A method is disclosed for fabricating a integrated device, such as a MEMS device. A first wafer is provided on an exposed surface with a layer of gold, gold alloy or gold compound. A second wafer is provided on its exposed surface with under-layer of gold, gold alloy or gold compound; and an over- of bismuth, bismuth alloy, a compound of bismuth, cadmium, cadmium alloy, a compound of cadmium compound, tin, tin alloy, or a compound of tin. The wafers are then brought into contact and bonded at their surfaces through the deposited layers.

1. Field of the Invention
The present invention relates to the field of integrated microdevices, such as, but not exclusively, Micro-Electro-Mechanical-Systems (MEMS), and in particular to a novel method of fabricating such devices at the wafer level. The invention is also applicable to the fabrication of biochips and like microdevices.
2. Description of Related Art
The manufacture of MEMS devices, such as micro-gyroscopes, micro-accelerometers, resonant accelerometers, micro-mirrors, micro-motors, micro-actuators and other such micro-devices integrating at least one moving part presents a very serious challenge in terms of packaging. A batch of such devices is fabricated on a wafer using semiconductor technology. The wafer is then diced to form the individual devices. Some MEMS-based devices require the encapsulation (known as wafer level packaging) to be done prior to dicing so that they are protected against contamination from particles and dicing slurry while during subsequent processing without the need for dedicated equipment or processes for dicing, mounting and molding procedures inside clean rooms. In addition, changes in atmospheric conditions can change the capacitance readout of micro-gyroscopes and micro-accelerometers without any corresponding change in acceleration, and because an increased relative humidity can increase stiction (that is the tendency of the moving parts to stick) of their moving parts, it is necessary to encapsulate the moving parts in a vacuum or in a controlled atmosphere.
In order to ensure the above functions, the moving parts are typically enclosed in a sealed micro-cavity under vacuum or under a specific pressure of dry nitrogen, dry forming gas or dry sulfur hexafluoride ambient. This is achieved by bonding two substrates together.
Since many MEMS devices must be operated under a high vacuum for ten years or more at a temperature of up to 150° C., the wafer-level packaging should allow the internal materials of the two substrates to be vacuum treated at a temperature much higher than the maximum operation temperature of 150° C. prior to sealing the wafer-level package under a vacuum in order to reduce the release of water vapor, hydrogen or other gases from these internal materials through this ten years period. In order to maintain the throughput of such vacuum wafer-level packaging process, this vacuum treatment at a temperature of about 400° C. should be followed by the wafer-level packaging bonding at a bonding temperature not too low compared to the 400° C. vacuum treatment so as to minimize the delays due to the cooling of the two substrates to the bonding temperature. A vacuum wafer-level packaging bonding temperature of 300–400° C. would be ideal for these applications.
However, many MEMS devices do not require to be operated under vacuum, and since many of these are very sensitive to the various coefficients of thermal expansion, it would also be desirable to develop an optional lower temperature wafer-level packaging process, which also guarantees reliable service for the expected life of the MEMS device in less stringent situations. Since the typical life of most semiconductor applications is about 10 years up to an operation temperature of up to 150° C., the lower temperature limit of the lower temperature wafer-level packaging process (the temperature at which de-bonding may occur) should not be lower then about 200° C. A non-vacuum wafer-level packaging bonding temperature of 175–300° C. would then be ideal for these applications.
The mechanical component or moving part of a MEMS device is mechanically released from surrounding materials so that it becomes relatively free to move and perform its sensing and/or actuation function. Wafer-level packaging involves the bonding of a sealed protective cap over this mechanical component following its mechanical release from its surrounding materials. Since such MEMS devices are typically fabricated from the combination of various materials having different coefficients of thermal expansion, it is important to minimize the exposure of the MEMS devices to high temperatures since this released component may be affected by the mechanical effects resulting from these various coefficients of thermal expansion Such effects can be observed as out-of-specification sensing or actuation, induced flexion and ultimately stiction between the released component and its surrounding materials, induced mechanical stress or mechanical failures in the released component, and unreliable performance in the field. In order to minimize these undesirable effects, it is necessary to minimize the temperature at which the mechanical component is exposed following its mechanical release from its surrounding materials. An upper limit of about 400° C. is desirable. Such an upper limit of 400° C. clearly limits the use of the well known direct wafer bonding (DWB) technique, which requires a temperature of about 1000 to 1200° C. to bond two polished silicon surfaces. Other lower temperature processes have been developed and are discussed herein. Unfortunately, none of these processes satisfy all the requirements for these special situations.
U.S. Pat. No. 6,232,150 titled 'Process for making microstructures and microstructures made thereby' (The Regents of the University of Michigan) as shown in FIG. 1, discloses the local bonding of Dow Corning's Pyrex 7740 glass to a phosphosilicate structure layer at a local temperature ranging between 820° C. and 1300° C. using an underlying polysilicon-based resistive micro-heater capable of locally heating the phosphosilicate bonding material to a high enough temperature as to allow bonding to the upper Pyrex 7740 glass. This reference employs a bonding temperature that is way over the desired upper limit of 400° C. It uses a temperature gradient which is necessarily associated with a mechanical stress gradient in the surrounding structures. Pyrex™ 7740 glass contains a lot of sodium in the form of Na2O and is thus absolutely incompatible with a CMOS line of products. This very serious limitation implies that the fabrication MEMS devices using in accordance with this reference must be limited to a dedicated tool set and cannot simply be introduced into a standard CMOS production line. Moreover, it also implies that this cited Pyrex-based wafer-level packaging technique will limit the development of future MEMS devices integrating optional sensing, control or communication devices and optional high-voltage actuation drivers.
While this patent requires the use of undesirable glasses, the process described is carried out at an excessive local temperature ranging between 820° C. and 1300° C., which may cause undesirable mechanical stress gradient in the surrounding structures.
U.S. Pat. No. 5,952,572 titled 'Angular rate sensor and acceleration sensor' (Matsushita Electric Industrial Co., Ltd.) is shown in FIG. 2. Three substrates composing the angular rate sensor described in U.S. Pat. No. 5,952,572 are bonded together as a sandwich structure using anodic bonding, as mentioned in column 7, lines 36–41 of the patent. This anodic bonding requires a Pyrex glass and the silicon and glass substrates to be heated to about 360° C. in a vacuum while a negative voltage of about 1000V is applied to the glass substrate with respect to the silicon substrate to be bonded with it.
This reference also uses Na2O-containing Pyrex glass and is thus also incompatible with CMOS technology. It also limits the development of future MEMS devices integrating optional sensing, control or communication devices and optional high-voltage actuation drivers. Since it requires the use of anodic bonding, it is also undesirable in most situations because substrates have to avoid contaminating the fabrication toolset with undesirable elements in the bonded glass.
FIG. 3 illustrates a Samsung process described in B. Lee, S. Seok, J. Kim, and K. Chun, 'A mixed micromachined differential resonant accelerometer', Work supported by ADD (Agency for Defense Development) through ACRC (Automatic Control Research Center) under Grant AC-041 and by the Brain Korea21 Project. Samsung employs a vacuum packaging technique again using the anodic bonding of a handle glass wafer to a Chemical-Mechanical Polished (CMP) 6 μm thick polysilicon layer deposited on a previously deposited and patterned TEOS (tetraethylorthosilicate) sacrificial layer.
FIG. 4 illustrates another Samsung process described in B. Lee, C. Oh, S. Lee, Y. Oh and K. Chun, 'A vacuum packaged differential resonant accelerometer using gap sensitive electrostatic stiffness change effect', Work supported by ADD (Agency for Defense Development) through ACRC (Automatic Control Research Center) under Grant AC-041. FIG. 4 shows that Samsung discloses another approach again using the anodic bonding of two substrates to produce accelerometers affected by the presence of residual gas (air) causing an observed damping effect. This paper clearly explains the effect or residual gases on the performance of MEMS devices and clearly explains the need for a vacuum sealed wafer-level package for such applications. Again, the use of this anodic bonding approach using sodium-based Pyrex glass is incompatible with CMOS technology and limits the development of future MEMS devices integrating optional sensing, control or communication devices and optional high-voltage actuation drivers.
The low-temperature bonding technology of Samsung Corporation also requires the use of anodic bonding.
FIGS. 5 and 6 show the surface micromachining performed at Robert Bosch GmbH. FIG. 5 shows that a glass frit technique is used to bond a 380 μm thick Cap wafer forming a 75 μm high protective cavity to ann-released section of a 10.3 μm thick polysilicon as to provide an hermetic seal. FIG. 6 shows the glass frit region between the protective Cap wafer and the substrate.
The glass frit technique typically requires a bonding temperature ranging between 350° C. and 475° C., and is slightly higher than the vacuum wafer-level packaging bonding temperature of 300–375° C. and certainly much higher than the non-vacuum wafer-level packaging bonding temperature of 175–300° C. Moreover, the vacuum performance of the dielectrics used in this glass frit bonding technique is questionable for vacuum wafer-level packaging bonding because low-temperature glasses are well known to be porous and thus not really suitable for use as vacuum-tight materials. A metal-based bonding technique compatible with vacuum applications would be preferred.
FIG. 7 is taken from U.S. Pat. No. 5,668,033 titled 'Method for manufacturing a semiconductor acceleration sensor device'. FIG. 7 shows that a machined cap silicon wafer covered with gold can be bonded to the silicon layer of a silicon-on-insulator (SOI) substrate in order to protect the underlying released MEMS structure.
FIG. 8 shows a gold-silicon phase diagram taken from the http://metal.or.kr/college/m etc/ele-index.html. This gold-silicon phase diagram indicates that when a clean oxide-free silicon surface is brought into intimate contact with a gold surface at a temperature of more than 360° C., a liquid silicon-gold eutectic phase will appear at the interface. Cooling the interface to a temperature lower than 360° C. will result in bonding.
This process described in this document indicates that an underlying silicon oxide diffusion barrier layer is formed on the bottom surface of the machined cap silicon wafer to prevent the diffusion of gold into the silicon of this machined cap silicon wafer and the associated voids thus created during the bonding process (column 7, lines 18–30). In order to enhance the adhesion of gold on this underlying oxide layer, a 0.1 μm thick titanium, nickel or chromium adhesion layer is deposited between the oxide diffusion barrier layer and the 2 to 5 μm thick gold layer deposited by a plating technique. The patterning of 100 to 300 μm wide gold bonding patterns is then performed using standard photolithography (column 6, lines 28–43).
This reference also indicates that these 100 to 300 μm wide gold bonding patterns are faced and aligned to corresponding silicon patterns of slightly larger width under vacuum or inert-gas atmosphere at a prescribed pressure and then pressed at a temperature of about 400° C. using a force of about 0.2 to 1.0 kg/mm2 for a period of tens of minutes before cooling below the eutectic temperature of 363° C.
The underlying silicon oxide diffusion barrier layer formed on the bottom surface of the machined cap wafer to prevent the diffusion of gold during the bonding process in undesirable for several reasons. Firstly, it constitutes another potential source of hydrogen or water vapor which limits the life of the sealed device. It decreases the infrared transparency of the overlying silicon substrate and then prevents the use of this wafer-level packaging technique for MEMS-based optical telecommunication switches operating in the C-Band (1300 nm), L-Band (1550 nm) and L-Band (1625 nm). It implies the contamination of a wet etch tool with gold if the underlying silicon oxide layers needs to be removed (i.e. as, for example, to allow the wafer-level packaging to be used for telecommunication infrared switches). In fact, this barrier layer is not really necessary because there are metal-based barrier metals which can be used under the gold layer and over the silicon layer to eliminate the interaction between gold and the silicon of the machined cap silicon wafer during the bonding process.
The photolithography of the gold layer, of the underlying 0.1 μm thick titanium, nickel or chromium adhesion layer and of the underlying silicon oxide diffusion barrier layer is undesirable because it implies gold contamination of the following of the equipment typically located in the CMOS fabrication area, namely the photoresist coater, scanner or stepper exposure equipment, develop equipment, etcher, photoresist stripper and surface cleaner.
FIG. 9 is taken from U.S. Pat. No. 6,265,246 titled 'Microcap wafer-level package' (Agilent Technologies, Inc.). The base wafer integrating a micro-device described in this patent is bonded to a matching cap wafer using cold welding of the bonding pad gaskets of the cap wafer to the periphery of the bonding pads of the base wafer integrating the micro-device. The arrangement assures an hermetic seal of the wafer-level package and electrical connections to the micro-device without passing through a seal. The bonding pads and bonding gaskets are selected from the following list of materials: silicon, aluminum, copper, gold, silver, alloys of these or compounds of these.
The following is the list of the possible binary combinations of bonding pairs of elements disclosed by Agilent's U.S. Pat. No. 6,265,246: silicon-aluminum; silicon-copper; silicon-gold; silicon-silver; aluminum-copper; aluminum-gold; aluminum-silver; copper-gold; copper-silver; gold-silver;
FIG. 10 shows the phase diagrams of the upper four pairs of elements involving silicon (silicon-aluminum; silicon-copper; silicon-gold; silicon-silver), as found at http://metal.or.kr/college/m etc/ele-index.html.
The silicon-aluminum pair has an eutectic temperature of about 580° C. The silicon-copper pair has an eutectic temperature of about 802° C. The silicon-gold pair has an eutectic temperature of about 360° C. and the silicon-silver pair has an eutectic temperature of about 835° C. It is clear that, out of these four pairs, the most interesting is still the silicon-gold pair, already disclosed by Nippon Denso's U.S. Pat. No. 5,668,033.
FIG. 11 shows the phase diagrams of two out of the three other pairs of elements involving aluminum (aluminum-copper; aluminum-gold; aluminum-silver), that can be found at http://metal.or.kr/college/m etc/ele-index.html.
The aluminum-copper pair has an eutectic temperature of about 548° C. The aluminum-gold pair is unstable and results in the so called purple plague. The aluminum-silver pair has an eutectic temperature of about 567° C. It is clear that none of these pairs is more interesting than the silicon-gold pair already disclosed by Nippon Denso's U.S. Pat. No. 5,668,033.
FIG. 12 shows the phase diagrams of the two other pairs of elements involving copper (copper-gold; copper-silver). The copper-gold pair has an eutectic temperature of about 910° C. The copper-silver pair has a eutectic temperature of about 780° C. It is clear that none of these pairs is more interesting then the silicon-gold pair already disclosed by Nippon Denso's U.S. Pat. No. 5,668,033.
FIG. 13 shows the phase diagrams of the remaining pair of elements involving gold (gold-silver. It is clear that the gold-silver pair is not more interesting then the silicon-gold pair already disclosed by Nippon Denso's U.S. Pat. No. 5,668,033.
None of the metal combinations disclosed in the U.S. Pat. No. 6,265,246 has a eutectic temperature lower than the silicon-gold pair already disclosed by Nippon Denso's U.S. Pat. No. 5,668,033.
Contrary to previously discussed Nippon Denso's U.S. Pat. No. 5,668,033, U.S. Pat. No. 6,265,246 does not describe the use of an underlying silicon oxide diffusion barrier layer formed on the bottom surface of the 200 μm thick matching cap wafer to prevent the diffusion of gold during the bonding process. The elimination of the silicon oxide diffusion barrier layer eliminates the potential source of hydrogen or water vapor which limits the life of the sealed device. It also prevents the decrease of the infrared transparency of the overlying silicon substrate and allows the use of this wafer-level packaging technique for MEMS-based optical telecommunication switches operating in the C-Band (1300 nm), L-Band (1550 nm) and L-Band (1625 nm). Finally, the elimination of the silicon oxide diffusion barrier layer prevents the contamination of a wet etch tool with gold if the underlying silicon oxide layers needs to be removed (for example, to allow the wafer-level packaging to be used for telecommunication infrared switches).
FIG. 14 shows the process sequence described by Agilent Technologies for the fabrication of a matching cap wafer. A first coat of photoresist is coated onto the silicon wafer, exposed and developed. A deep silicon etch is performed so as to penetrate about 100 μm into the 200 μm thick silicon wafer and produce a series of deep trench patterns. Following photoresist stripping, a very thin diffusion barrier layer of chromium, nickel or titanium is deposited by sputtering just before the in-situ deposition, in the same sputtering equipment, of a 0.2 to 0.3 μm of gold seed layer (column 4, lines 1 to 9). A second pattern of thick high-viscosity photoresist is then coated, exposed and developed onto this gold seed layer to allow the electroplating of a thick pattern of gold into the developed pattern of photoresist, using the seed gold layer as electrode. Following plating, the photoresist is removed using conventional photoresist stripping, thus leaving a gold pattern whose thickness is only limited by the thickness of the high-viscosity photoresist. The remaining gold seed layer and metal-based diffusion barrier layer are etched away using a conventional etching process. The passages at column 4, lines 60 to 67, and column 5, lines 1 to 11 teach that, an adhesion layer (not shown) can be deposited on the base wafer and that an unspecified material be deposited by sputtering or evaporation. Patterning is done by photolithography, the unwanted unspecified conductive material is etched away, and the photoresist is removed. Alternately, the photolithography is performed, followed by the deposition of the adhesion layer and the unspecified conductive material, followed by the removal of the photoresist material and of the unwanted unspecified conductive material to form the bonding pads.
As described in column 5, lines 12 to 18, and as shown in FIG. 15 the matching cap wafer is turned-over and aligned to the base wafer and compressed together at temperatures up to 350° C. until "cold weld" bonding occurs for the gold plated pattern of the matching cap wafer to bond to the unspecified material of the bonding pad of the base wafer and create a completely hermetically sealed volume for the protected microdevice. The matching cap wafer is then thinned using conventional wafer grinding or lapping and polishing so that the previously deep etched trench patterns extend all the way through the matching cap wafer.
The above description of the bonding technique does not allow a person skilled in the art of bonding to reproduce the results stated without knowing the nature of the material deposited on the base wafer the technique used to "remove" this unwanted material following photoresist removal.
FIG. 16 is taken from U.S. Pat. No. 6,297,072. FIG. 16 shows that the so called "Indent-Reflow-Sealing" (IRS) technique described in this patent uses a first chip located on a first substrate fabricated by depositing and patterning a metallization seed layer; preparing a polyimide mold to define the solder ring; and electroplating the solder ring in the mold using an optional nickel spacer whose thickness is only limited by the thickness of the polyimide mold. Preferably the eutectic 63% tin-37% lead solder, but alternately one of the following solders: 5% tin-95% lead, tin-lead-2% Silver, indium, 80% gold-20% tin, tin-silver, tin-silver-copper or tin-bismuth can be used. After removal of the polyimide mold, a shearing tool or an indenter is used to create an indent region in the electroplated solder ring, as shown in FIG. 17. This indent later disappears during the later reflow of this solder ring.
A second chip located on second substrate is then fabricated. As shown in FIG. 18, first there is carried out the deposition and patterning of a suitable metal ring adequately wettable and capable of forming a stable intermetallic compound with the electroplated (electrodeposited) solder ring of the first chip of the first substrate. Examples of a suitable metal ring are most stable tin-copper or alternately, tin-nickel covered with a thin layer of 0.1–0.3 μm of gold to prevent nickel oxidation. A tin-nickel/gold metal ring with a gold layer thicker than 0.3 μm will result in an unreliable solder connection.
A pre-treatment "flip-chip" alignment is carried out after suitable plasma treatment of both substrates to enhance adhesion following reflow of the solder ring. As shown in FIG. 19, a flip-chip aligner and bonding system is used to make the solder ring of the first chip of the first substrate face and be aligned with the metal ring of the second chip of the second substrate.
As a pre-bonding step, both chips are heated to a temperature well below the melting point of the solder ring (a softening temperature well below the reflow temperature), such as 120–160° C. for a 67% tin-37% lead. Pre-bonding is then carried out by the application of a bonding force (typically 2 kgf or 19.62 N) for the two chips of the two substrates so that they stick as shown in FIG. 20. This allows the pair to be moved to the reflow oven. The temperature and bonding force is optimized for the chosen solder ring, the solder ring history and the type of metal ring used.
In the reflow oven, the cavity formed between the aligned and pre-bonded solder ring and metal ring is evacuated and then filled with the required pressure of desired gas, such as nitrogen, nitrogen-hydrogen mixtures or sulphur hexafluoride. Alternately, the vacuum cavity can be vacuum evacuated. FIG. 21 shows that the evacuation and filling of the cavity is performed through the indent region previously created in the solder ring.
The temperature of the oven is raised to about or above the melting point of the solder ring but below the melting point of all other materials used. As shown in FIG. 22, the solder ring melts to close the indent region resulting in a hermetically sealed cavity with a controlled ambient. The result is the eutectic bonding between the electroplated 67% tin-37% lead solder ring and the 0.1–0.3 μm gold layer of the tin-nickel/gold metal ring.
This patent then describes the bonding of an indented 63% tin-37% lead, 5% tin-95% lead, tin-lead-2% silver, indium, 80% gold-20% tin, tin-silver, tin-silver-copper or tin-bismuth solder ring electroplated over an optional electroplated nickel spacer of a first substrate to a tin-copper or tin-nickel/gold metal ring of a second substrate using two pieces of equipment: a single-wafer pre-bonder and a batch oven to seal the indented solder ring by reflow under a controlled pressure of nitrogen, nitrogen-hydrogen or sulphur hexafluoride or under vacuum.
The use of the solder ring on the first substrate allows the bonding to the tin-copper or tin-nickel/gold metal ring of the second substrate to be performed at temperatures that are much lower then the gold-silicon eutectic temperature of 363° C.
Unfortunately, there are a couple of issues with the above bonding strategy. It is yet not clear which of the two substrates (the substrate with the solder ring or the substrate with the metal ring) would integrate the MEMS structure to be mechanically released using vapor HF. If it is the solder ring, then the electroplated solder material would be exposed to vapor HF. Unfortunately the exposure of a noble metal (such as gold) to vapor HF would be preferred. If it would be the tin-copper or tin-nickel/gold metal ring then either a tin-copper or tin-nickel/gold structure would then be exposed to vapor HF. The first tin-copper situation is undesirable because it does involve the exposure of a noble metal to vapor HF. The second tin-nickel/gold situation is more desirable because it implies that gold would be exposed to vapor HF. Unfortunately, the underlying metal would then be tin-nickel, which is not a desirable choice.
FIG. 23 shows the phase diagram of the tin-nickel system. FIG. 23 shows that the exposure of tin-nickel to temperatures in excess of 231° C. results in the formation of liquid tin under the gold layer, which is absolutely undesirable if the bonding is to be performed to the upper gold layer.
The above described technique requires the precise indentation of the solder ring to allow the two substrates to be aligned. They must then be pressed together, and heated to a softening temperature so as to stick the two substrates together in the alignment and pre-bonding equipment. This step is followed by the formal reflow of the solder ring at the required pressure of nitrogen, nitrogen-hydrogen or sulphur hexafluoride gas or under proper vacuum level in another batch reflow equipment. This complex indentation process, align-press-heating pre-bonding step in one equipment and this release of the applied force and reflow in an independent batch reflow equipment has a number of disadvantages. The process is very complex; of questionable reliability because the applied force is released before the actual reflow of the solder ring, thus allowing the various interfaces to be "de-stick" during manipulation and loading into the batch reflow oven; and unnecessarily costly to manufacture.
The review of the prior art indicates that it is associated with several problems. The well known direct wafer bonding (DWB) technique requiring a bonding temperature of about 1000 to 1200° C. operates at too a high temperature to be used for MEMS involving a mechanically released sensitive structure.
The technique described in U.S. Pat. No. 6,232,150 involving the bonding of Dow Corning's Pyrex 7740 glass using a polysilicon-based resistive micro-heater capable of locally bonding silicon to this Na2O-based phosphosilicate requires an excessively high local temperature ranging between 820° C. and 1300° C. This technique is undesirable for many reasons: It causes undesirable mechanical stress gradients in the region of the mechanically released sensitive structure; its Na2O-based Pyrex 7740 glass is absolutely incompatible with CMOS technology. It also limits the development of future MEMS devices integrating optional sensing, control or communication devices and optional high-voltage actuation drivers because its structural sodium contaminates the manufacturing equipment with sodium and results in devices affected by sodium-induced threshold voltage instabilities and sodium-induced slow trapping reliability problems.
The anodic bonding process described in U.S. Pat. No. 5,952,572 (Matsushita Electric Industrial Co., Ltd.) and in the two Samsung Prior Art publications B. Lee, S. Seok, J. Kim, and K. Chun, 'A mixed micromachined differential resonant accelerometer', Work supported by ADD (Agency for Defense Development) through ACRC (Automatic Control Research Center) under Grant AC-041 and by the Brain Korea21 Project; B. Lee, C. Oh, S. Lee, Y. Oh and K. Chun, 'A vacuum packaged differential resonant accelerometer using gap sensitive electrostatic stiffness change effect', Work supported by ADD (Agency for Defense Development) through ACRC (Automatic Control Research Center) under Grant AC-041; allows the reduction of the bonding temperature of the Na2O-based Pyrex 7740 glass to about 360° C. using vacuum anodic bonding. This anodic bonding process has the same sodium-related contamination issues and the same limitations concerning the development of future MEMS devices integrating optional sensing, control or communication devices and optional high-voltage actuation drivers. Moreover, this technique requires the application of undesirable high voltage gradients (1000 to 2000 volts). Added to this sodium-based limitation, the anodic bonding process requires a 1000 to 2000 volts voltage drop to be applied between the Pyrex 7740 glass and the fresh silicon surface to be bonded.
A glass frit bonding technique reported by Robert Bosch GmbH in the following two prior art publications reduces the bonding temperature to a range between 350° C. and 475° C. This temperature is still slightly higher than the vacuum wafer-level packaging bonding temperature of 300–375° C. and certainly much higher then the non-vacuum wafer-level packaging bonding temperature of 175–300° C. Moreover, the vacuum performance of the dielectrics used in this glass frit bonding technique is questionable for vacuum wafer-level packaging bonding situations because low-temperature glasses are well known to be porous and not really suitable as vacuum-tight materials.
The silicon-gold eutectic bonding technique reported in U.S. Pat. No. 5,668,033 (Nippon Denso Co., Ltd.) describes a process involving the bonding of a cap silicon wafer to a base wafer. The bottom surface (bonding side) of the cap wafer is covered with a silicon oxide layer preventing the diffusion of gold into silicon and associated voids created during the bonding process. To enhance the adhesion of gold on this underlying oxide layer, a 0.1 μm thick titanium, nickel or chromium layer is deposited between the oxide diffusion barrier layer and the gold layer. Standard photolithography is used to pattern the gold bonding patterns before flipping the cap wafer, aligning the gold bonding patterns to the facing silicon patterns of the base wafer and pressing these gold patterns to these silicon patterns at a temperature of about 400° C. for tens of minutes before cooling below the eutectic temperature of 363° C. This fabrication technique of the cap silicon wafer and of the base silicon wafer (free from native oxide) has serious limitations which cannot provide a stable and repeatable bonding. This limitation is acknowledged by the inventors of this patent who describe the use of an hydrofluoric acid based etching solution to eliminate the natural oxide formed on the surface of these facing silicon patterns (column 5, lines 53 to 56). Since the base wafer typically incorporates hundreds of sensitive and mechanically released MEMS structures, it is generally not possible to use hydrofluoric acid based etching solutions because their surface tension will cause the surface of the released MEMS structure and the surface of surrounding structures to stick together, a well known problem in MEMS fabrication. Since this native oxide naturally re-grows in ambient conditions over a typical time period of a few hours (a time period equivalent to the bonding of a couple of pairs of wafers at a typical throughput of a few tens of minutes per pair of wafers) and since there are typically forty-eight wafers to bond in succession (one set of twenty-four cap wafers to bound to one set of twenty-four base wafers) the native oxide can then re-grow during delays between steps, during manipulations and even while bonding the first pairs of wafers. The eutectic bonding of gold to bare silicon is then a non-repeatable and unstable process requiring a lot of special precautions which, thus not desirable. If this MEMS device is a photonics MEMS device (such as a MEMS-based optical telecommunication switch) requiring the cap wafer to be infrared transparent in the C-Band (1300 nm), L-Band (1550 nm) and L-Band (1625 nm) then the underlying silicon oxide diffusion barrier layer formed on the bottom surface of the cap wafer as to prevent the diffusion of gold during the bonding process in also undesirable because it will increase the absorption loss of the switch. If the MEMS device is a vacuum-based automotive device such as a micro-gyroscope, then the presence of the underlying silicon oxide diffusion barrier layer formed on the bottom surface of the cap wafer will also constitute a potential source of hydrogen or water vapor which and then limit the life of the vacuum-sealed device. Finally, the use of standard photolithography to pattern the gold layer and the underlying 0.1 μm thick titanium, nickel or chromium adhesion layer is undesirable because it implies gold contamination of the following list of equipment typically located in the CMOS fabrication area: photoresist coater, scanner or stepper exposure equipment, develop equipment, etcher, photoresist stripper and surface cleaner.
U.S. Pat. No. 6,265,246 also describes a process involving the bonding of a cap silicon wafer to a base wafer. Unlike Nippon Denso's U.S. Pat. No. 5,668,033, Agilent Technologies' U.S. Pat. No. 6,265,246 describes the use of a very thin diffusion barrier layer of chromium, nickel or titanium as replacement of the silicon oxide diffusion barrier layer, thus eliminating the upper-described issues with this silicon oxide diffusion barrier. The analysis of the various phase diagrams shows that, out of the silicon-aluminum, silicon-copper, silicon-gold, silicon-silver, aluminum-copper, aluminum-gold, aluminum-silver, copper-gold, copper-silver and/or gold-silver possible bonding combinations reported in U.S. Pat. No. 6,265,246, the bonding combination providing the lowest possible bonding temperature is still silicon-gold, with an eutectic temperature of 363° C. Curiously, the passage at column 5, lines 12 to 18 states that the cap wafer is turned-over, aligned to the base wafer and compressed together at temperatures up to 350° C. until "cold weld" bonding occurs for the gold plated pattern of the matching cap wafer to bond to the unspecified material of the bonding pad of the base wafer and create a completely hermetically sealed volume for the protected micro-device. As previously mentioned, the bonding technique does not allow a person skilled in the art of bonding to understand the so-called "cold weld" at temperatures up to 350° C. or to reproduce the results of the patent. Since the "cold weld" temperature is lower than the silicon-gold eutectic temperature of 363° C., the pads cannot be covered by silicon and the wafer-level bonding cannot be performed by silicon-gold eutectic bonding.
The "Indent-Reflow-Sealing" (IRS) technique reported in U.S. Pat. No. 6,297,072 describes a process involving the bonding of an indented 63% tin-37% lead, 5% tin-95% lead, tin-lead-2% silver, indium, 80% gold-20% tin, tin-silver, tin-silver-copper or tin-bismuth solder ring electroplated over an optional electroplated nickel spacer of a cap wafer to a tin-copper or tin-nickel/gold metal ring of a base wafer using two pieces of equipment: a single-wafer pre-bonder and a batch oven to seal the indented solder ring by reflow under a controlled pressure of nitrogen, nitrogen-hydrogen or sulfur hexafluoride or under vacuum. The use of one of the proposed solder rings on the cap wafer allows the bonding to the tin-copper or tin-nickel/gold metal ring of the base wafer at a temperature which is much lower then the gold-silicon eutectic temperature of 363° C. There are a couple of issues with this metallurgical process. In order to release the mechanical structure of the MEMS, the metal ring of the base wafer has to be exposed to vapor HF prior to bonding the cap wafer. Unfortunately, if the metal ring of the cap wafer is the proposed tin-copper, then the exposure to vapor HF is undesirable because this tin-copper is not a noble metal. If the metal ring of the cap wafer is the proposed the tin-nickel/gold, then the exposure to vapor HF would be more desirable because gold is a noble metal not affected by vapor HF exposure. Unfortunately, this proposed tin-nickel/gold metal ring implies that the tin-nickel metal under the gold bonding layer can form liquid nickel at a temperature of only 231° C., which is absolutely undesirable if the bonding is to be performed to the upper gold layer. The required precise indentation of the solder ring allowing the two substrates to be aligned, pressed together and heated to a "softening temperature" as to "stick" the two substrates together in the alignment and pre-bonding equipment, followed by the formal reflow of the solder ring in another batch reflow equipment makes the proposed process very complex, very costly to manufacture and of questionable reliability because the applied force is released before the actual reflow of the solder ring, thus allowing the various interfaces to be "de-stick" during manipulation and loading into the batch reflow oven.

Wafer level packaging technique for microdevices


A method for measuring and characterizing the Air Traffic Control Radar Beacon System without interrupting service which comprises a computer-controller system which captures the beacon radar system emissions during one radar rotation and software which extracts and plots the two antenna signal patterns. Data is collected for 50 microseconds during each degree of antenna rotation, triggered by the first pulse of the three pulse signals, and is then stored in separate omni-directional and directional arrays for subsequent plotting. Data is also collected for 50 microseconds during each one-tenth degree of antenna rotation within the directional antenna main lobe.

1. Field of the Invention
This invention relates to the Air Traffic Control Radar Beacon System, and more particularly to a method for characterizing the system antenna patterns during actual use.
2. Description of the Related Art
In the United States, the Federal Aviation Administration uses a radio navigation system known as the Air Traffic Control Radar Beacon System (ATCRBS) to determine the range and azimuth of transponder-equipped aircraft. The ATCRBS consists of a ground-based interrogator-receiver that interrogates the aircraft transponder and is unique in its use of two separate radio emission patterns, known as antenna patterns, to improve the accuracy of the measured aircraft locations. The radar beacon system depends on a precise relationship between these two antenna patterns for satisfactory performance. The emissions for each pattern consists of a series of pulses which are transmitted at separate times but on the same radio frequency, thus precluding the use of conventional antenna pattern measurement techniques to characterize the two patterns.
One of the signals emitted by the ATCRBS system is roughly the same strength in all directions from the antenna and is therefore known as the omni-directional signal. The second signal emitted is a directional signal which is much stronger in one direction than any other. The direction of maximum strength is called the main lobe of the antenna, and the antenna is rotated either physically or electrically so that all azimuths are swept by this signal during a fixed period of time. Both the omni-directional and directional signals are emitted at the same frequency, 1030 MHz, but are pulsed so that they are separated in time. A standard sidelobe suppression system (SLS) emits an initial pulse from the directional antenna, followed by a pulse from the omni-directional antenna, and then one or more additional pulses from the directional antenna. A variation called the improved sidelobe suppression system (ISLS) differs in that it emits the first pulse from both antennas. This helps remove azimuth ambiguities caused by signal reflections.
Conventional receiving equipment is unable to separate the pulses emitted by the directional antenna from those emitted by the omni-directional antenna. In order to measure the antenna patterns of the two antennas using these systems, each of the signals must be measured separately with the other turned off, degrading air traffic control information. It is possible to use a pulse separating system connected to the receiver to measure both signals simultaneously, but this is bulky and expensive and is therefore seldom used. Disrupting the service of the ATCRBS system or using expensive specialized equipment are currently the only methods available for making these measurements.

Method for characterizing air traffic control radar beacon system antenna patterns

The United States of America as represented by the Secretary of Commerce


An enclosure for small animals which is wearable on the front or back of an animate bearer. Straps are attached to a solid base upon which a complete enclosure is fastened. The straps allow the pet enclosure to be suspended from the shoulders and waist of a bearer, fully freeing the arms and hands. The enclosure is substantially transparent and completely air-permeable, allowing the pet to view outside events and to experience the textures of the outdoors in safety and comfort. A solid base forms the floor of the enclosure allowing the pet to have firm footing, as well as room to sit, stretch, or lie down. The base is of a recessed configuration, contoured to the body of the bearer to provide distribution of the animal's weight close to the bearer and centered for balance, as well as to provide a means for containing pet waste where it can be easily cleaned. Ample access to the enclosure is provided by fasteners in both the front and rear of the enclosure, from both the left and the right sides. The enclosure is flexible when erect allowing use in limited spaces, yet sufficiently resilient to return to its original shape. Optionally, the enclosure is transformable into a hand-carried enclosure; it also interfaces with a seat of a vehicle, and is fully collapsible for easy storage. This invention is a complete enclosure which provides containment and control of an enclosed pet, allowing small animals to be included in many activities which would not otherwise be practical or possible.

This invention is generally related to the field of pet carriers, and specifically to a lightweight collapsible enclosure which can be worn on the front or back of an animate bearer, enabling pet owners to include their domestic pets in activities heretofore not practical or possible.
Pet carriers to date have been generally confined to two categories: 1) Enclosures constructed of solid material such as plastic, or flexible material such as nylon fabric, with a handle and/or strap for carrying; and 2) Sack-like receptacles for pets made of flexible material such as nylon or cotton, with straps for the shoulders and/or waist of the bearer and designed to be worn.
The primary disadvantage of the sack-like carriers has been that the pet within has no rigid footing and hence is not held in comfort. Also, the sack-like carriers have not entirely enclosed the pet as is required for access to many public places; this further poses a danger for the pet to escape, as the pet is not fully contained. Additionally, the matter of pet waste has not been addressed in these carriers.
The enclosures constructed of solid material such as plastic have been rigid carriers with handles, and deficient in that the bearer's hands are occupied, and also these carriers generally have not been adjustable in size, and many have had limited ventilation and/or viewability for the pet.
The flexible enclosure carriers with handles and/or straps have been deficient in that the bearer's hands or arms are required even with the use of a shoulder strap, in order to balance the weight of the pet on an animate bearer, or to prevent the strap from slipping off the shoulder. These carriers are not truly wearable, but more precisely comport with the category of those which are carried on a shoulder of an animate bearer. The primary disadvantage of the single shoulder strap carriers is that the weight distribution of the load is asymmetrical, unbalanced, and therefore uncomfortable on the animate bearer, thus requiring the use of the bearer's arms or hands to steady the load to prevent subjecting the enclosed animal to jolting action during transport. A further disadvantage is that many of these enclosures tend to collapse onto themselves and the pet within when the carrier is set down and the handle is released. Yet another disadvantage of these prior carriers is limited ventilation and/or viewability for the enclosed pet.
The present invention overcomes these limitations by providing an adjustable, collapsible, full enclosure which is substantially transparent and fully air-permeable, and retains its shape when set down. Moreover, the present invention can be worn conveniently fully freeing the arms and hands. In this worn configuration, the lightweight enclosure is attached to shoulder and waist straps in a balanced manner, and can be worn centered on the front or back of an animate bearer. The rigid base is patterned to center the pet's weight close to the body of the animate bearer. This feature encourages the respective masses of the enclosure/pet and the animate bearer to become tangent and the centers of gravity to nearly coincide on a central horizontal axis, thereby mitigating the inherent conflict of inertia of two independent moving masses. The result is a positive and consistent center positioning of the load, with optimized stability when the enclosure is worn, thus fully freeing the arms and hands. The intersecting downward planes of the floor of the base also allow for the concentration of pet waste where it may be easily removed.
The present invention is a full enclosure which restrains the animal safely and comfortably within. Because of the pliant properties of the enclosure and its structural members, the enclosure is also comfortable against the body of the bearer when worn. Further, the enclosure is self-adjustable in size and shape for placement in confined spaces such as under airline seats, yet possesses enough resiliency to spring back to its original shape and size ehen no longer in a confined space.
The present invention further offers a versatility heretofore not found in pet carriers. The enclosure is not only wearable, but it may also be easily configured into a convenient hand-carried mode.
The invention further is attachable in an elevated position to the rear or to the front of the seatback of a passenger seat in a vehicle, for safely containing and restraining a pet while enabling enclosed pet to view the outside. It may also interface with a vehicular seat belt in a non-elevated position, for accommodating the various pet transport needs of the pet custodian.
The following patents and publications are cited as being pertinent to the subject matter of this invention, although all are distinguishable from the invention:
______________________________________ U.S. Pat. DOCUMENTS INVENTOR U.S. PAT. NO. ______________________________________ Halpin, A. 2,538,778 Patten, J. 3,156,213 Schluttig, P. L. 3,481,311 Priddy, Jr. W. S. 3,509,855 Springer, et al. 3,850,144 Albright, D. J. 4,220,119 Yamamoto, Y. 4,484,540 Doyle, R. L 4,644,902 Delino, Jr. J. 4,781,147 Davis, L. D. 4,803,951 Goetz, C. R. 4,852,520 Slawinski, N. 4,977,857 ______________________________________
__________________________________________________________________________ OTHER PUBLICATIONS PUBLICATION ISSUE/PAGE # TITLE __________________________________________________________________________ Pedigrees, The Pet Catalog Christmas, 1989, p. 19 "Personalized Pet Carrier" Pedigrees, The Pet Catalog Christmas, 1989, p. 19 "Pet Car Seat" Pedigrees, The Pet Catalog Christmas, 1989, p. 07 "Pet Safety Belt" Pedigrees, The Pet Catalog Christmas, 1989, p. 14 "Pet Carrier" Pedigrees, The Pet Catalog Christmas, 1989, p. 25 "Pet Totes" Pedigrees, The Pet Catalog Christmas, 1989, p. 35 "Totes" Du-Say's Catalog Spring, 1989, p. 31 "Carry Your Pet Anywhere" Du-Say's Catalog Spring, 1989, p. 31 "Fits Under Any Airline Seat" Du-Say's Catalog Spring, 1989, p. 31 "Ridin' High Car Seat" Du-Say's Catalog Spring, 1989, p. 31 "Buckle Up Your Pet" Master Animal Care Catalog Spring, 1990, p. 10-11 "Carriers" Cat Care Catalogue Spring, 1990, p. 6 "Cabin Kennel" Pedigrees, The Pet Catalog Holiday, 1990, p. 4 "Pet Totes" Cat Fancy Magazine (Monthly) Spet., 1990, p. 60 "Pac-A-Pet" Animail Pet Care Products circa 1991 p. 20 "Sherpa Bag" __________________________________________________________________________
The Springer (U.S. Pat. No. 3,850,144) patent teaches the use of a portable pet carrier made of woven fabric and having a stiff bottom insert. However, the Springer device contemplates that the animal's head will extend out of the enclosure, which can produce discomfort in some animals when thus restrained about the neck. Without full enclosure of the pet such as provided by the present invention, the Springer carrier is inadequate for situations where full enclosure is necessary, such as within airline cabins. Further, the Springer carrier has only one strap and therefore only one attachment point on the bearer, thus distributing the pendulous weight of the enclosed pet uncomfortably on the bearer for any extended period of time. This limits the mobility of the bearer for various activities, as well as causing a turbulent ride for the pet passenger unless the arms or hands are used to steady the carrier when the bearer is in motion. The present invention overcomes these problems with multiple points of attachment which center and stabilize the enclosure on the bearer, fully freeing the arms and hands, and is comfortable to wear. The weight of the pet is concentrated to the rear center of the base and close to the torso of the bearer preventing the enclosure from bouncing and swinging when the bearer is in motion.
Other pet totes which have been marketed, "Doggi-Dudd" (Pedigree, the Pet Catalog, Holiday 1990, p.4) and "Sherpa Bag" (Animal Pet Care Products. circa 1991, p.20), utilize the same basic elements of design as Springer, and therefore suffer from the same design disdvantages enumerated above relative to Springer, with the exception of 1) no dedicated aperture for the head of the pet; and 2) incorporating ventilation panels inserted on two of the four flaccid sides of the carrier. The "Doggi-Dudd" and the "Sherpa Bag" carriers completely collapse onto the enclosed pet when the carrier is set down and the handle is released.
The patents to Albright (U.S. Pat. No. 4,220,119), Yamamoto (U.S. Pat. No. 4,484,540), Patten (U.S. Pat. No. 3,156,213), Halpin (U.S. Pat. No. 2,538,778), and Schluttig (U.S. Pat. No. 3,481,311) teach portable collapsible pet carriers which require use of the hands for either carrying or steadying the device. The present invention is a significant advance over these devices in that it 1) comprises a lightweight less cumbersome easily convertible design which can either be hand-carried, or worn; and 2) remains erect yet pliant when deployed and therefore self-adjustable in height and shape; and 3) completely frees the arms and hands when worn, and balances the enclosure weight and load allowing the bearer to include the pet in activities such as bicyling, hiking, boating, and so on.
The Doyle (U.S. Pat. No. 4,644,902) patent teaches a pet carrier comprising a sling of flexible sheet material having a body portion with holes for receiving the pet's legs, and which may be slung over the shoulder or carried in the hand. Transporting a pet in this manner can cause discomfort and even panic in some animals, while further suffering from the disadvantages of a carrier which is not an enclosure. The present invention differs substantially in that it is a full enclosure, with a comfortable footing for the animal, designed preferably to be worn centered on the front or back of the bearer.
A similar device known is "Personalized Pet Carrier" (Pedigrees Pet Catalog Christmas 1989 p.19). It is a wearable apron-like carrier with a front pouch for carrying a pet, and has no solid base for the pet's footing or for its waste, and no manner of restraining the pet from escape or falling out. In addition, this device is 1) not designed to be hand-carried, but only to wear; and 2) not a full enclosure.
Another similar device has been commercially available under the name "Pac-a-Pet" indicating a U.S. Patent Pending (Cat Fancy, September 1990 p.60). The product is 1) is not designed to be hand-carried, but only to wear; 2) has no solid base, making it difficult or impossible for a pet within to stand, sit, stretch or lie down; and 3) is not an enclosure, but rather utilizes a collar clasp to control/restrain the pet by the neck.
The patent to Davis (U.S. Pat. No. 4,803,951) teaches a collapsible pet enclosure with mesh walls. However, Davis differs from this invention in that the device of Davis is only designed for use in a motor vehicle, and only to attach to the frame of a car window. The present invention is a considerable improvement over Davis in that it is adaptable; it can be 1) worn; or 2) hand-carried; or 3) free-standing; or 4) interfaced with a conventional waist seat belt on a seat in vehicles, to protect pet from injury, to protect driver from distraction, and to protect upholstery from pet waste.
Car restraints for pets such as that shown in other publications (Du-Say's Spring 1989 p.31. and Pedigrees, The Pet Catalog Christmas 1989 p.7, and p.19) either: 1) are insufficiently small restricting the pets from lying down; 2) fail to supply a base protecting the car seat from the pets; and/or 3) harness an animal in a position which may be uncomfortable for extended periods of time.
The Delino (U.S. Pat. No. 4,781,147) patent teaches a portable pet carrier having an inverted wire basket hinged onto a rigid flat base, with an opening at the top of the wire basket for an animal's head. The Delino device is adapted to be mounted on the back of a bicycle or held to the seat of a car by a seat belt. Unlike the present invention, it is not adaptable for wearing, and is not a full enclosure.
The patent to Goetz (U.S. Pat. No. 4,852,520) teaches a portable pet carrier with a handle and wheels which may be carried or pulled. It may be disassembled into two halves, but is not collapsible or adjustible in height, nor can it be worn. It is a variation of the most common type of pet carrier on the market.
The patent to Slawinski (U.S. Pat. No. 4,977,857) teaches a bag-like carrier with wheels which can be carried or pulled. It more closely comports with and suffers from the same disadvantages as enumerated above with respect to Albright, Yamamoto, Patten, Halpin and Schluttig, which are portable pet carriers requiring the use of the hands to steady the unbalanced load while carrying. Because none of these carriers provides multiple points of attachment designed to insure a constant and centered stable positioning of the load, the hands cannot be free, nor can the user be comfortable while in motion. The present invention overcomes these disadvantages by completely freeing the arms and hands when worn centrally, and constantly balancing the weight of the enclosure and the load through a wide range of motion.
The device referred to as "Cabin Kennel" (Cat Care Catalog, Spring 1990, p.6) is designed specifically for use under an airline seat. This device fails to offer humane sitting/standing/stretching room for the pet, as promulgated by the American Society for the Prevention of Cruelty to Animals (ASPCA). The present invention, being flexible, may fit under an airline seat when required, but may also then be positioned on an custodian's lap during appropriate times of the flight, enabling the pet to be comforted by the custodian, or allowing the pet to sit/stand/stretch within the enclosure while complying with the present rules and policies of many common carriers such as airlines.
The device referred to as "Fits Under Any Airline Seat" (Du-Say's Catalog Spring 1989 p.31) is not a full enclosure as required by most common carriers.
Pet enclosures which are flexible (Cat Care Catalog Spring 1990 p.6, and Pedigrees The Pet Catalog Christmas 1989 pp.14, 25 and 35, and Du-Say's Spring 1989 p.31) which are flexible, share the primary disadvantages of 1) being marginally ventilated or transparent; and/or 2) being limited to carrying by hand or on one shoulder in an unbalanced fashion; and/or 3) collapsing onto the enclosed pet when set down.
Pet enclosures which are rigid (Master Animal Care Spring 1990 pp.10 and 11) share the primary disadvantages of 1) requiring hand-carrying 2) not being adjustable in height, and 3) not being completely collapsible.
The remainder of the listed prior art patents and publications diverge more starkly from the present invention.
The wearable pet enclosure combines two elements as its primary objective heretofore not accomplished in pet carriers: 1) wearable, and 2) enclosure, in addition to the other important features in preferred and more specific embodiments. As shown, prior carriers which are complete enclosures have not been wearable, and wearable carriers have not been complete enclosures.
Accordingly, it is a primary object of this invention to provide a means for carrying a pet in a fashion which allows the bearer to wear the device comfortably with arms and hands free to perform other tasks. Prior carriers have had a handle for hand carrying, or a shoulder strap which is not truly wearable, but rather requires the arm(s) or the hand(s) to steady the device, or to keep it from slipping off the shoulder.
A further object of this invention is to provide multiple points of attachment to the body of the bearer thereby distributing the weight of the wearable pet enclosure centered and resistant to independent motion.
Another object of this invention is to provide a device which completely encloses a pet while optionally providing the pet with a clear view of outside events, while also being viewable by outside observers. The enclosure of the present invention further provides unlimited ventilation for the pet within, while protecting the pet from insects, pests, and many common outdoor dangers.
Another further object of this invention is to provide a pet carrying device which has a rigid floor allowing the pet to stand, sit, stretch or lie down while being transported. The rigid base also provides a positive fastening means for the wearable strapping suspension which preferably is threaded through the various front and rear strap slots formed in the base. Buckles or other fastening means may be affixed to the ends of the suspension strapping to facilitate use and reconfiguration from the wearable to the carriable mode.
Another further object of this invention is to provide a recessed portion of the rigid floor for centering the pet's weight close to the body of the bearer, as well as for accumulating pet waste where it can be contained and easily cleaned.
Another further object of this invention is to provide a means by which the enclosure may be adjustable in height by deforming the enclosure, allowing the enclosure to fit in locations of restricted or irregularly shaped volume such as under airline seats or various other constrained travel environments.
Another further object of this invention is to provide a means by which the empty enclosure may be completely collapsed for storage in smaller spaces.
Another further object of this invention is to provide a pet enclosure which is not only wearable, but also easily hand-carriable by a bearer; this dual purpose has not been available in other pet carriers.
Another further object of this invention is to provide a complete enclosure which can be attached to the front or to the rear of the seatback of a vehicular seat, by fastening the shoulder suspension straps and waist straps around the seatback. This application contains and restrains the pet in an elevated postion while allowing the enclosed to pet to view the outside.
It is yet a further object to provide an enclosure which can accommodate seat belts for safety within a vehicle, while yet allowing adequate room for a pet's comfort while so restrained.
Another further object of this invention is to provide a cover for the pervious walls of the carrier to protect the pet within from outside elements when necessary.
Yet another object is to provide a pouch attached to the enclosure for carrying such a cover, as well as for carrying a limited amount of pet supplies.
A further object is to provide a wearable pet enclosure, which is traffic safety-conscious, utilizing brightly colored contrasting trim integrated at strategic locations of the suspension straps and the enclosure for maximum visibility while walking, hiking, biking and so forth.
Another further object of this invention is to provide access by the hand of the bearer to the inside of the enclosure, from the top, front and back of the carrier and also from the left or the right side. This facilitates placing or removing the animal within, petting the animal, or cleaning any waste. Additionally, the entire tent enclosure which fastens to the base is removable to further facilitate cleaning the base or the enclosure.
Viewed from a first vantage point it is an object of this invention to provide a lightweight wearable and carriable pet enclosure protecting the pet from many outside hazards and thereby giving the pet a sense of security, while yet allowing the pet to experience the stimulus of the outdoors and view outside events. Many indoor pets have a curiosity about the outdoors, but live in areas where it is inappropriate or unsafe to allow them outside.
It is a further object of this invention to provide a enclosure which is well-suited for a variety of animals such as small-breed dogs up to 20 pounds, cats, and rabbits. A perch option is also included in this enclosure for pet birds.
Viewed from a second vantage point it is an object of this invention to enable pet owners to include a pet in activities for which carriers currently available are not suited, such as hiking, fitness walking, bicycling, boating, camping, and other excursions.
It is a further object of this invention to provide an alternative to leashes which are not well suited for some pets; this invention provides a means by which the indoor pet's need for outdoor stimulation may be safely satisfied, while bringing enjoyment and novelty heretofore unavailable to the pet owner.
Viewed from a third vantage point it is an object of this invention to provide a wearable platform which supports animals without requiring the use of arms or hands, comprised of a custom-contoured rigid base which conforms on one side to the body contour of a bearer, a plurality of suspension straps which attach to the base and extend around the waist and shoulders of the bearer, a raised edge preferably formed with the floor around the perimeter of the base and extending upward which helps the platform to retain objects thereon, and a pervious tent which removably attaches to the base, completing the enclosure.
As demonstrated above, prior pet carriers which have comprised complete enclosures require the use of arms or hands to carry or to steady the load on one shoulder of the bearer, making such carriers more closely related to the category of carried enclosures and not truly wearable. When worn in a preferred manner, the wearable pet enclosure becomes a synergistic embodiment of the bearer and allows and promotes intimate interaction with the enclosed pet, even while the bearer is in ambulatory motion. The primary distinction between carrying and wearing in this context, is that when worn, the present invention behaves as a seamless balanced extension of the torso of the bearer, completely freeing the arms and hands while providing a complete enclosure for the pet.
Other carriers which have been designed to be worn and to free the hands have not been complete enclosures, but have been sac-like, and inadequate for the comfort and safety of the pet, as well as inappropriate for many situations where a full enclosure is required. None of the prior carriers have had a dual purpose such as the present invention, allowing for the easy and complete transformation of use from the wear-mode to the hand-carry mode. Furthermore, no pet enclosure to date has provided a entirely wearable enclosure leaving the arms and hands completely free.
Further objects and advantages of this invention will become apparent from consideration of the drawings and ensuing description.


A finger attachable writing apparatus includes a housing with a top wall, a bottom wall and a peripheral wall that is attached to and extends between the top and bottom walls. The housing has a first end and a second end. A conduit is coupled to and is angled downwardly from the bottom wall. An aperture extends into a free end of the conduit and into an interior of the housing. A finger engaging member is attached to the housing and is configured to releasably attach the housing to a finger. An ink dispensing assembly is mounted in the housing. The ink dispensing assembly is positionable in a deployed position extending outwardly of the conduit or in a stored position. The ink dispensing assembly is configured to dispense ink from the conduit when in the deployed position.

1. Field of the Invention
The present invention relates to writing devices and more particularly pertains to a new writing device for attaching to a finger to allow a person to write without gripping a writing utensil.
2. Description of the Prior Art
The use of writing devices is known in the prior art. However, these devices have limitations, such as the angle at which they can be used and cannot be used by those persons having limited gripping abilities. Therefore, while these devices fulfill their respective, particular objectives and requirements, the need remains for a device that can be attached to a finger for easy use and should include an ink dispensing system that is not dependent upon the angle of the device as it is being used.


A cooling member for an integrated circuit, the member having a recess therein for receiving the integrated circuit and contacting a portion of exterior surfaces of the integrated circuit and a portion of metal leads extending from the integrated circuit; in one aspect, such a member with a plurality of such recesses for accommodating a plurality of such integrated circuits; and in one aspect, such a system including a metal heat sink.

1. Field Of The Invention
This invention relates in general to the field of cooling integrated circuits and, in particular, to the field of providing a system for conducting heat away from the body and leads of integrated circuits.
2. Description Of Related Art
Efforts at the thermal management of electronic devices are old and well known, as are the adverse effects of excessive temperatures on the performance and integrity of such devices.
Early attempts to control and dissipate heat generated by or around electronic devices included air ventilation apparatuses such as fans to pull ambient air into and exhaust it from a cabinet or chassis containing heat-generating electronic devices. A variety of passive cooling techniques have more recently been employed with semiconductor devices to dissipate heat produced by them. These techniques have included: mica pads; silicone grease; the use of mechanical heat sinks with cooling fins; such heat sinks with a bag of thermally conductive fluid; thermoelectrically cooled devices; ceramic-slab metal-plate composite heat sinks; and thermally conductive elastomeric blankets, to name a few.
Thermal interface materials for removing heat from electronic devices are described in "CHO-THERM.RTM. Thermal Interface Materials," Chomerics, Inc. These products include either a silicone or urethane elastomer binder with boron nitride, magnesium oxide or aluminum oxide as a thermally conductive filler and a reinforcement made from fiberglass cloth or a polyimide or polyester film. These products are electrically non-conductive. In one prior art method of thermal management of heat produced by an integrated circuit, the heat flows from the integrated circuit to a blanket of a thermally conductive elastomer disposed on the integrated circuit and then to a mechanical finned metal heat sink disposed on the blanket.
U.S. Pat. No. 5,006,924 discloses a heat sink for use with high density integrated circuit substrates which includes a compliant bag containing thermally conductive fluid disposed adjacent a typical finned heat sink. The bags rest on the tops of the integrated circuits. A pump may be utilized to circulate fluid through a plurality of interconnected bags.
U.S. Pat. No. 5,012,324 discloses a heat sink body for use with electronic power components which has a ceramic slab covered on both sides with metal plates.
U.S. Pat. No. 5,012,325 discloses a thermoelectrically cooled integrated circuit package.
U.S. Pat. No. 5,006,925 discloses a three-dimensional electronic chip package with a plurality of semiconductor device substrates and a cooling channel through the package for circulation of a cooling fluid therethrough.
U.S. Pat. No. 5,014,161 discloses an elastomeric matrix with conductive elements embedded therein which contact conductive contact pads which in turn contact semiconductor devices.
U.S. Pat. No. 5,010,386 discloses an insulator-separated vertical complementary semiconductor device having an insulating layer.
U.S. Pat. No. 5,006,923 discloses a substrate for mounting integrated circuits in which a non-conductive sealing glass frit covers the integrated circuits.
Although each of the prior art techniques result in some heat transfer from the protected electronic devices, it is desirable to increase the amount of heat transferred from integrated circuits (and to increase the rate of this transfer). It is also desirable to accomplish this in an effective manner which does not substantially increase the overall size of apparatuses employing integrated circuits. Finally, it is desirable to accomplish this with relatively simple materials which are readily available and easy to work with.


A mechanism for use with a bus provided from parallel, capacitively-coupled bus lines to restrict a number of possible transitions on the bus to a number that is smaller than the maximum number of possible transitions so that data transmissions on the bus occur at a transmission rate which is higher than the transmission rate allowable if the number of transitions had not been restricted.

On-chip and inter-chip communications are realized by circuit devices called buses. A bus consists of parallel, aligned, similar wires that in most cases are on the same metal layer. Buses transmit units of information at a given fixed rate R (e.g., byte/sec). Some parallel buses are provided from parallel, capacitively-coupled transmission lines. The capacitive coupling introduces delay in the propagation of a signal from bus driver to bus receiver. Buses with capacitively-coupled lines have the property that the propagation time required for a signal depends upon the change (or transition) between the new data set to be transmitted on the lines and the last data set that was transmitted on the lines. Prior techniques estimate the delay associated with the capacitive coupling by modeling worst-case transitions. Typically, the rate R specified for such a bus is chosen to be sufficiently small to accommodate the delays associated with all the possible transitions.
To complicate matters further, the properties of the bus wires do not scale with technology in a favorable way. In modern technologies, in particular, deep sub-micron (DSM) technologies, there is increased capacitive coupling between the lines of buses due to the smaller distances between the lines as well as the higher aspect ratio (height/width) necessary to maintain a linear resistance of reasonable size.

Method and apparatus for reducing delay in a bus provided from parallel, capacitively coupled transmission lines


The invention relates to a monitoring device 1 for monitoring a man-overboard situation in a ship section 5, wherein the ship section 5 is monitored by video technology using at least one camera 2, and the camera 2 is designed to provide surveillance in the form of video data. The monitoring device comprises an analysis device 9, said analysis device 9 having an interface 10 for transferring the video data, and the analysis device 9 is designed to detect a moving object in the ship section 5 on the basis of the video data and determine a kinematic variable of the moving object. The analysis device 9 is also designed to determine a scale on the basis of the video data and the kinematic variable in order to determine the extent 8 of the moving object and evaluate the moving object as a man-overboard event on the basis of the extent 8 thereof.

A monitoring device for monitoring a man overboard situation in a ship section is proposed. The ship section is monitored by video technology by means of at least one camera, the first camera being designed to provide the monitoring in the form of video data. The monitoring device comprises an analysis device which is designed to detect a moving object in the ship section based on the video data.
On ships, and especially on passenger ships and cruise ships, it is a known problem that passengers can fall overboard unnoticed during the voyage. Such events are referred to as man-overboard events. The chances of survival after such an event decrease with the time that elapses before the event is discovered.
Shipping companies are very interested in detecting a man-overboard event as soon as possible. Government regulations and/or insurance policies are also exerting increased pressure on shipping companies to include such events in their monitoring processes as far as possible.
In the case of cargo ships, for example, there is provision for equipping individuals with special armbands or other technology which they must wear or carry about their person in order to allow detection of man-overboard events. Radar-based methods are relatively expensive and require a large number of sensors.
Image—and/or video-based approaches have the problem of being susceptible to interference based on the wide range of possible events and objects, and due to a dynamic background of the moving vessel, with many events being detected and evaluated as false man-overboard events.

Monitoring device, and method for monitoring a man overboard situation


Water-dilutable brushing paints based on water-soluble alkyd resins rendered water-soluble through neutralization of methacrylic acid groups thereon are described. The brushing paints have favorable applicational properties, especially with regard to wet-edge time and brushability.

This invention relates to water-dilutable paints. More particularly, the invention relates to water-dilutable brushing paints based on water-soluble alkyd resins rendered water-soluble through neutralization of carboxy groups contained thereon derived from methacrylic acid.
U.S. Pat. No. 4,333,865 discloses a method for preparing aqueous alkyd resin emulsions whereby the carboxy groups necessary for the stabilization of the emulsion are introduced through graft polymerization of methacrylic acid and other vinyl and acrylic monomers to a part of the unsaturated oil fatty acids used in the alkyd resin formation. All of the disclosed products contain polyethylene glycols or intermediates containing polyethylene glycols as an essential constituent. The polyethylene glycol is not introduced through an ester linkage which may be saponifiable in an aqueous medium, but rather is introduced through intermediate products. The products are used as such or in combination with urethane-modified alkyd resins. With these products air-drying, water-dilutable paints can be produced which excel in applicational properties and have outstanding storage stability. The products of the aforementioned patent containing polyethylene glycol have as another essential characteristic a maximum acid value of 35, and preferably an acid value below 25 mg KOH/g. Higher acid values invariably lead to paint films with insufficient water resistance. Although neutralization of the acid groups can be accomplished with alkali hydroxides or ammonia, paints with good gloss are obtained only when neutralization is with the use of organic amines.
According to AT-PS 375,667, emulsifier resins obtained through graft copolymerization of (meth)acrylic acid and other monomers based on polyethylene glycol-modified fatty acid polyolesters are used to prepare aqueous emulsions in combination with urethane-modified alkyd resins. Emulsions of this type are particularly suited for use in paints for wood; however, on aging, the paints yellow.
DE-OS 24 16 658 discloses that the reaction of acrylic acid or methacrylic acid with polyunsaturated fatty acids at from 250xc2x0 C. to 300xc2x0 C. provides adducts which can be processed to water-dilutable alkyd resins through esterification, preferably with polyglycols. The products have a relatively poor drying speed, since a major part of the fatty acids is lost for film formation through adduct formation at the time of dimerization which takes place at the necessarily high reaction temperature. Furthermore, pigment wetting is substantially reduced through the adduct formation without use of polyglycols in the subsequent alkyd resin formation.
Alkyd resins, free of polyethylene glycol, having an acid value of from 35 to 70 mg KOH/g, substantially based on methacrylic acid units which are used as xe2x80x9cemulsifier resinsxe2x80x9d in the emulsion polymerization of vinyl and/or (meth)acrylic copolymers are described in commonly assigned European Application No. 87116502.3 filed Nov. 11, 1987, laid open May 18, 1988 under EU-OS 0267562. The methacrylic acid units are introduced into the alkyd resin as graft polymers. Emulsions are obtained according to the invention permitting the formulation of excellent air-drying, water-based paints. However, one disadvantage of such emulsions is with respect to aqueous brushing paints. Thus, the so-called wet-edge time which is the time within which the next part of a surface can be brushed without leading to leveling defects, or sticking of the brush when brushing the bordering areas, is very short. Although this time lag can be up to sixty minutes for a good brushing paint based on solvents, for dispersion paints it is often only two to three minutes. With the best alkyd copolymer dispersions, wet-edge time is at best about ten minutes. Accordingly, brushing of larger areas, such as doors, etc., can be accomplished only with difficulty by less experienced painters.
Surprisingly it has now been found that air-drying brushing paints can be formulated having good wet-edge time based on alkyd resins, water-soluble upon partial or total neutralization of the carboxy groups, which are substantially graft copolymers of unsaturated fatty acids with blends of methacrylic acid and acryl-methacryl-vinyl monomers which carry no functional groups other than a double bond, and which preferably form benzene-dilutable homopolymers.
The present invention, therefore, is concerned with water-dilutable brushing paints based on alkyd resin binders, water-soluble upon partial or total neutralization, containing the normal pigments, extenders, and auxiliary solvents. The binder of the invention is an alkyd resin with a content of unsaturated fatty acids of from about 30% to 70%, preferably 40% to 60%. The free carboxy groups of the resin, corresponding to an acid value of from about 25 to 70 mg KOH/g, are derived up to at least 80% from methacrylic acid units. The methacrylic acid is graft polymerized prior to alkyd resin formation, together with 30% to 55% by weight, calculated on the resulting graft copolymer, of other vinyl and/or (meth)acrylic monomers carrying no reactive functional groups other than the xe2x80x94Cxe2x95x90Cxe2x80x94 bond, to a part of the unsaturated fatty acids content of the alkyd resin. The conditions of the polymerization are controlled in order that the comonomers used together with methacrylic acid are such that up to at least 80% of the monomers when separately polymerized form benzene-soluble homopolymers.
The brushing paints of the present invention have a wet-edge time of twenty to forty minutes and are similar to alkyd resin paints based on solvents with regard to brushability, i.e., ease of brushing, leveling, radiance, and build. Also, the paints of this invention are at least equal to known alkyd resin emulsions with regard to storage stability and drying characteristics, two properties essential for brushing paints. Surprisingly, the products show good pigment wetting and gloss without the polyethylene glycols normally used in the production of alkyd resin emulsions. However, the use of polyethylene glycols is not precluded by this invention. In special cases they may help in paint formulation, for example when using some special pigments.
Another advantage of the alkyd resins of this invention is that the products can be neutralized with ammonia instead of organic amines to provide good wetting and radiance characteristics. The organic amines are not favored from the ecological standpoint.
The alkyd resins used for the brushing paints of the present invention are water-soluble through at least partial salt formation at their carboxylic groups with ammonia, alkali hydroxides, or organic amines. It is noted that the water-solubility does not necessarily lead to clear solutions. As known to one skilled in the art, the resins in these solutions have large resin micelles, so that the solutions may be opaque or even turbid.
As an essential feature, the alkyd resins of this invention have an acid value of 25 to 70 mg KOH/g, at least 80% of the acid groups being derived from methacrylic acid units, which, together with 30% to 55% by weight, calculated on the weight of the resulting graft copolymer, of other vinyl and/or (meth)acrylic monomers which carry no functional groups other than the xe2x80x94Cxe2x95x90Cxe2x80x94 double bond, are graft polymerized in a separate reaction step to a part of the unsaturated fatty acids used in the alkyd preparation. The selection of the ethylenically unsaturated monomers, in addition to methacrylic acid, is made under the condition that at least 80% of the monomers will form benzene-soluble homopolymers when separately polymerized. The alkyd resins are prepared using conventional processes.
The content of drying and/or semi-drying fatty acids of the alkyd resins of this invention is from about 30% to 70% by weight, preferably between 40% and 60% by weight of the alkyd resin. Of these fatty acids, from about 10% to 40% by weight, calculated on the resin weight, is introduced in the form of fatty acid-methacrylic acid, graft copolymers.
The preferably used alkyd resins are characterized in that they contain from about 10% to 25% by weight of polyalcohols with 2 to 6 hydroxy groups, 10% to 20% by weight of aromatic and/or aliphatic dicarboxylic acids, 0% to 15% by weight of cyclic and/or polycyclic monocarboxylic acids, and 0% to 5% by weight of a polyethylene glycol. The products have an intrinsic viscosity of from about 7 to 16 ml/g, measured in chloroform at 20xc2x0 C.
For the preparation of the grafted fatty acids, unsaturated fatty acids are used having an iodine value of over 135 (preferably 160-200) and with the double bonds being predominantly in isolated position. Suitable acids are, for example, linseed oil fatty acid, safflower oil fatty acid, and the fatty acids hempoil, Lallemantia-oil, Perilla-oil and Stillingia-oil, optionally in admixture with up to 25% of dehydrated castor oil fatty acid prepared through isomerization.
The fatty acid copolymers include 30% to 50% by weight of the above-mentioned fatty acids, 10% to 25% by weight methacrylic acid, and 30% to 55% by weight of other monomers which carry no other functional groups other than the xe2x80x94Cxe2x95x90Cxe2x80x94 double bond, the sum of percentages being 100. The monomers used besides methacrylic acid are preferably (meth)acrylic compounds, particularly monomers which form benzene-soluble homopolymers. Suitable monomers include the esters of methacrylic and acrylic acid with n-butanol, iso-butanol, tert.-butanol, or 2-ethylhexanol. Vinyltoluol can be used for the adjustment of the optimum glass transition temperature of the copolymer and of the film hardness resulting therefrom.
The graft polymerization is carried out in order that the main quantity of the fatty acid, optionally in the presence of small quantities of inert solvents, is heated to 110xc2x0 C. to 150xc2x0 C. and the monomer blended with a suitable initiator, and the remaining fatty acid is added within the course of a few hours. The reaction is then held at reaction temperature until a determination of the solids content indicates a conversion of more than 95%. Suitable initiators include di-tert.-butylperoxide, tert.-butyl-perbenzoate, and cumol hydroxide.
The fatty acid/methacrylic acid graft copolymers are processed to water-soluble alkyd resins with further fatty acids. Suitable fatty acids for this step are vegetable or animal fatty acids with an iodine value of over 120. It is preferred that a part of the double bonds are in conjugated position. Suitable fatty acids include soya oil fatty acid, linseed oil fatty acid, safflower oil fatty acid, and dehydrated castor oil fatty acid.
Suitable polyols and dicarboxylic acids for use in preparing the alkyd resins are those conventionally used in the production of conventional alkyd resins. The preferred components are trimethylolethane, trimethylolpropane, pentaerythritol and sorbitol as the polyol, and ortho- or iso-phthalic acid as well as adipic acid as dicarboxylic acids. The film hardness can be controlled by using cyclic or polycyclic monocarboxylic acids such as rosin acids or benzoic acid, along with the dicarboxylic acids. Polyethylene glycols with a molecular weight of from about 1000 to 3000 can be introduced in an amount up to about 5%.
The esterification can be carried out through concurrent heating of all components. When using high melting raw materials, such as pentaerythritol and iso-phthalic acid, it can be desirable to first esterify the acids, polyols and dicarboxylic acid until a clear melt has formed, and subsequently add the fatty acid-methacrylic acid copolymers. The esterification is then carried to a final degree of about 90% of the concentration of methacrylic acid. Since these acid groups have a tertiary position in the copolymer chain, they are sterically hindered and, accordingly, it is theorized that they esterify with substantially reduced speed and, thus, at the end of the reaction, provide the major portion of the remaining acid groups which render the resin water-soluble. Since these acid groups are linked to the alkenyl chains of the fatty acids with xe2x80x94Cxe2x95x90Cxe2x80x94 bonds and the preferred grafting sites of the isolated unsaturated fatty acids are the activated CH2-groups of the C11- and C14-chain, there is a long molecular segment between the acid groups and the ester linkage which blocks the attack of water. Thus, the alkyd resin components according to the invention are superior in hydrolysis resistance over the known water-dilutable alkyd resins based on partial esters of o-phthalic acid, iso-phthalic acid, or trimellitic acid.
Suitable organic water-tolerant co-solvents include the methyl-, ethyl- and butyl-ethers of ethylene glycol, diethylene glycol, 1,2-propylene glycol, and dipropylene glycol. In portions, fairly water-tolerant solvents can be coemployed, such as n-butanol and iso-butanol. The total content of organic solvents in the finished paint should be kept as low as possible.
For the neutralization of the acid groups, ammonia is preferred. Other suitable neutralizing agents are the amines such as triethylamine, dimethylethanol amine, and the alkali hydroxides such as KOH, NaOH, and LiOH.
The alkyd resins are used either in neutralized or unneutralized form as a solution in water-tolerant solvents. The preferred form of the products are aqueous emulsions, since, in this way, the content of organic solvents can be substantially reduced.
The water-dilutable brushing paints of the present invention are prepared in a conventional manner. They may be applied as a clear varnish, for example as a water-dilutable wood glaze; or in pigmented form, as primers for wood or metal surfaces; or as trade paints and do-it-your-self paints. The pigments, extenders, and additives, such as the siccatives, anti-skinning aids, antifoams, etc., are known to one skilled in the art.
The paints are preferably prepared whereby the emulsions are mixed with the pigments and the additives are dispersed in suitable milling equipment such as a pearl mill, three roll mill, disperser, or the like.
The paints are applied by brush, dripping, spraying, or flow coating to dry at room temperature; or the paints can be force-dried at elevated temperatures of up to about 100xc2x0 C.
The following examples illustrate the invention without limiting its scope. Parts and percentages are by weight unless otherwise stated. The intrinsic viscosity values are measured in chloroform or dimethylformamide (DMF) at 20xc2x0 C. and are recorded as ml/g.
(I) Preparation Of Fatty Acid/Methacrylic Acid Copolymers
Copolymer Cl: 30 parts linseed oil fatty acid and 5 parts xylol are heated to 135xc2x0 C. to 140xc2x0 C. At this temperature, within 6 to 8 hours, two blends are added simultaneously and continuously; one blend consisting of 32 parts isobutylmethacrylate, 6 parts vinyl toluol, and 21 parts methacrylic acid; and the other blend consisting of 11 parts linseed oil fatty acid, 3 parts tert.-butylperbenzoate, 1 parts dibenzoylperoxide (50%), and 5 parts xylol. At the end of the addition, the reaction temperature is maintained until a determination of the non-volatile content shows a polymerization conversion of at least 95%. One part of tert.-butylperbenzoate can be added, if desired, to accelerate the reaction. The copolymer has an acid value of 209 mg KOH/g and an intrinsic viscosity of 5.5 (DMF).
(II) Preparation Of Alkyd Resins
According to the composition listed in Table 1, alkyd resins are prepared as follows: In a suitable reaction vessel the components of Part 1, as set forth in Table 1, are esterified at 230xc2x0 C. until a clear melt has formed. After another hour, Part 2, as set forth in the Table, is added and the batch reacted at 200xc2x0 C. until the final values have been attained. After stripping the inert solvent from the copolymer, the batch is diluted with ethyleneglycol monobutylether to a solids content of 87% and then emulsified at 50xc2x0 C. with a diluted aqueous ammonia solution. The quantity of ammonia and water is chosen such that a pH-value of 8.2 to 8.4 and a solids content of 40% results. The resin solutions are milky to transparent liquids, with pronounced structured viscosity.

Water-dilutable brushing paint based on water-soluble alkyd resins