The present invention relates to compositions and methods for treating equines, such as horses, afflicted with equine protozoal myeloencephalitis or EPM. The therapeutic compositions comprise a combination of pyrimethamine and a sulfonamide, preferably, sulfadiazine, in the absence of known therapeutic amounts of trimethoprim.

The present invention relates to compositions and methods for treating equines, such as horses, afflicted with equine, protozoal myeloencephalitis of EPM. EPM is a debilitation neurologic disease of equines which can affect the brain, the brain stem, spinal cord, or any combination of these three areas of the equine""s central nervous system. EPM is caused by infection by the protozoan parasite Sarcocystis neurona (recently referred to as Sarcocystis falcatula). There is no vaccine or approved animal drug product available for effectively treating this disease in horses.
Although the symptoms and effects of EPM have been recognized since the 1970""s, it was not until 1991 that the protozoan parasite that causes EPM was cultured from a horse and given the name Sarcocyscis neurona. The horse is an aberrant, dead-end host, as infectious forms of the parasite are not passed from horse to horse or from infected horse to a definitive or true intermediate host. Recent investigations indicate that the feces of the opossum (the definitive host) are the source of the infection for horses.
EPM occurs in much of North America. Serologic surveys conducted in central Kentucky one county in Pennsylvania, and the entire states of Ohio and Oregon, have revealed that approximately fifty percent (50%) of the horses in the surveyed areas have been exposed to the above-noted protozoan parasite. A positive serum test indicates exposure to the parasite, not necessarily the presence of an active form of the disease. The incidence of the active disease is much lower.
In studies that looked at the distribution of seropositive cases geographically, it was found that climatic factors may affect exposure rates; i.e., an increase of freezing days or a very hot environment was associated with a decrease in the numbers of horses exposed to the parasite. EPM appears to have a sporadic distribution, although outbreaks have occurred on farms in Kentucky, Ohio, Indiana, Michigan and Florida.
A horse of any age, breed, or sex may be affected by EPM. The disease has occurred in a horse of two months of age, as well as one in its thirties. In fact, any horse demonstrating neurologic abnormalities should be considered a candidate for EPM affliction.
Clinical signs of the condition depend on the location of the organism within the central nervous system. These signs include weakness, malposition of a limb, muscle atrophy, spinal ataxia, or xe2x80x9cwobblingxe2x80x9d and/or head tilt with asymmetry of the face (e.g., eyelid, ear, or lip). A severely EPM-affected horse may become recumbent and unable to rise. Lameness not traceable to orthopedic disease or any combination of the above signs may occur with EPM. Other unusual signs may also occur.
In most cases, an affected horse is bright and alert with a normal appetite, although it may be dysphagic (i.e., unable to eat) and may act as if it is choked with feed material coming from its nose. Hematological and biochemical blood values are usually in the normal range.
Diagnosis of EPM is based on clinical signs and on testing of the horse""s cerebrospinal fluid (CSF). Originally, the diagnosis was based on the presence of antibodies to Sarcocystis neurona in serum, though it is now known that a positive serum test cannot be used to make a diagnosis; such positive serum test simply indicates exposure to the parasite, not necessarily presence of the disease. Cerebrospinal fluid testing is now believed to be the most useful test to assist in the diagnosis of this disease in a live horse.
Currently available treatment of horses with EPM is expensive and typically requires a duration of at least ninety (90) days. In some cases, treatment lasts indefinitely. This current treatment involves the adaptation of tablets intended for human use. Thus, pyrimethamine tablets are administered along with tablets containing a trimethoprim-sulfonamide combination. Typically, the two types of tablets are crushed and placed in suspension for oral administration. These medications should be administered one hour prior to feeding hay and are accompanied with frequent, periodic, veterinary, neurologic examinations during the treatment period.
Discontinuation of therapy is usually based on the administration of medication thirty days beyond the plateau of clinical improvement or disappearance of antibody to the protozoa from the CSF. Suboptimal dosing or intermittent therapy has no proven efficacy.
Adverse effects of therapy may include anemia, abortion, diarrhea and low white blood cell counts. Both medications for treatment of EPM inhibit folic acid metabolism. Unlike horses, however, the protozoan is unable to utilize pre-formed folic acid. Supplementation with folic acid or folinic acid (40 mg orally, once a day) and/or brewer""s yeast may help prevent adverse side effects. It is suggested, however, that folic acid not be administered at the same time as the pyrimethamine because of competitive inhibition and absorption.
The gametocytocidal and sporontocidal effects of 2 g sulfadiazine with 50 mg pyrimethamine in a chloroquine-resistant strain of Plasmodium falciparum is disclosed in Chemical Abstracts, Volume 69: 50900p (1968). Primaquine diphosphate, pyrimethamine and sulfadiazine were said to show causal prophylactic activity against rodent malaria, Plasmodium berghei yoelii, as disclosed in Chemical Abstracts, Volume 77: 109339h (1972). A three component composition of pyrimethamine, sulfadiazine and cycloguanil-HCl for treating rodent malaria is disclosed in Chemical Abstracts, Volume 96: 40845t (1982). Similarly, sulfadiazine sodium has been used to enhance the activities of certain antiinfective drugs against infections caused by pyrimethamine-susceptible or pyrimethamine-resistant strains of P. falciparum and P. vivax in owl monkeys. See, Chemical Abstracts, Volume 92: 15581p (1980).
There are a number of articles describing the treatment of Toxoplasma gondii with pyrimethamine and sulfadiazine, but at a ratio that uses a very large amount of sulfadiazine relative to pyrimethamine. See, e.g., Chemical Abstracts, Volume 78: 52708s (1973) (1 mg/kg pyrimethamine and 100 mg/kg sulfadiazine for mice); Chemical Abstracts, Volume 85: 72303d (1976) (2 mg/kg pyrimethamine and 100 mg/kg sulfadiazine for cats); Chemical Abstracts, Volume 99: 133330y (1983); Chemical Abstracts, Volume 101: 87339t (1984); Chemical Abstracts, Volume 122: 45806w (1995) (1 mg/kg pyrimethamine and 50 mg/kg sulfadiazine for monkeys); Chemical Abstracts, Volume 122: 253089n (1995) Chemical Abstracts, Volume 123: 102131u (1995) describes the daily administration of 25 mg pyrimethamine and a total of 2 g sulfadiazine to prevent toxoplasmic encephalitis relapse in AIDS patients.
The patent literature includes many descriptions of methods for treating protozoan-mediated diseases. McHardy, in U.S. Pat. No. 5,273,970, states that a protozoal disease, toxoplasmosis, may be controlled to a certain extent using pyrimethamine together with a sulfonamide. This patent asserts that baquiloprim can be used for the treatment and/or prophylaxis of protozoal infections in animals, including humans. Although the baquiloprim can be used as the sole active ingredient, it can be co-administered with a sulfonamide. A long list of suitable sulfonamides is provided, most preferably sulfadiazine, sulfamethoxazole, sulfadimethoxine, sulfadoxine, sulfamoxole, or sulfadimidine.
In U.S. Pat. No. 4,599,416, granted to Kompis, a process for the preparation of aqueous compositions of sulfonamides and sulfonamide potentiators for the treatment of bacterial infections in humans and animals is described. A long list of potential sulfonamides is provided. The xe2x80x9cpotentiatorsxe2x80x9d are described as denoting compounds that increase the antibacterial activity of sulfonamides more than additively. An equally long xe2x80x9claundryxe2x80x9d list of such potentiators is provided, which includes trimethoprim and pyrimethamine. Other patents dealing with protozoan parasites include: U.S. Pat. No. 4,293,547, granted to Lewis et al. for the treatment of malaria; U.S. Pat. No. 4,340,609, granted to Chou (various protozoal infestations); U.S. Pat. No. 4,368,193, granted to Argoudelis et al. (malaria); U.S. Pat. No. 4,728,641, granted to Tubaro et al. (protozoal infections generally); U.S. Pat. No. 4,992,444, granted to Stevens et al. (trypanosomes and malaria); and U.S. Pat. No. 5,486,535, granted to Marr et al. (Toxoplasma gondii).
Beech, in Veterinary Medicine/Small Animal Clinician, pp. 1562-1566 (December 1974) described a condition in eight (8) horses with signs of neurological disorder. On the assumption that toxoplasmosis was involved, the author suggested that pyrimethamine and sulfadiazine, used successfully against toxoplasma in man, might be useful in horses.
Welsch, B. B. recommended the use of pyrimethamine (0.5 mg/kg), combined with a 20 mg/kg two-part mixture of sulfadiazine (16.7 mg/kg) and trimethoprim (3.3 mg/kg), to treat horses suffering from EPM. See, Welsch, B. B. , in The Compendium North American Edition, Equine, Morris, D. D. (Ed.) (1991) pp. 1599-1602.
Two articles by Clark et al., which appeared in American Journal of Veterinary Research, Volume 53, Number 12, pages 2292-2295 and 2296-2299 (December 1992), discuss the pharmacokinetics of intravenously and orally administered pyrimethamine in horses. The first article, at page 2292, states that clinical reports indicate the possible value of treatment of horses with protozoal encephalomyelitis with pyrimethamine in combination with trimethoprim and sulfonamides. On the other hand, the second article, at page 2299, concludes that the oral administration of 1 mg pyrimethamine/kg once a day for 10 days apparently does not present a serious toxicological problem to horses.
Hence, despite a great deal of past and on-going effort, there remains an unfulfilled need for a treatment for EPM-afflicted equines, particularly horses, which is not only effective but is also convenient to administer to maximize compliance and reduce the emergence of resistant strains. In particular, prior compositions for the treatment of EPM involve three-component mixtures, including pyrimethamine, sulfadiazine and trimethoprim. Moreover, where prior compositions contained pyrimethamine and sulfadiazine as the active ingredients, such compositions used very small ratios of pyrimethamine to sulfadiazine limiting their effectiveness to treating malaria only and hampering their usefulness in other pathological conditions, like protozoan-mediated diseases, especially EPM. The fact is that there is currently no approved drug or drug combination for the treatment of EPM.
Quite surprisingly, it has now been discovered that an effective, convenient method of treating EPM is realized by the administration to an equine suspected of being afflicted with EPM of therapeutic amounts of pyrimethamine and a sulfonamide, preferably sulfadiazine. The relative weight ratio of pyrimethamine to the sulfonamide may range from about 1:10 to about 1:30, preferably, about 1:15 to about 1:25, and most preferably about 1:20 in the case of a composition comprising pyrimethamine and sulfadiazine.
It should be pointed out that the compositions of the present invention do not contain significant amounts of trimethoprim, certainly less than about two-thirds of the weight amount of sulfadiazine present. Preferably, the therapeutic compositions used for the treatment of EPM are substantially free of trimethoprim, most preferably having no trimethoprim at all. Similarly, the methods of the present invention do not rely on the presence of significant amounts of trimethoprim in effecting successful treatment of EPM, using substantially the pyrimethamine and a sulfonamide as the principal active ingredients against the pathologic agent, namely, the organism Sarcocystis neurona in EPM. Hence, the methods of the present invention do not include the co-administration of known therapeutic amounts of trimethoprim.
In a preferred embodiment of the invention, the afflicted equine, e.g., a horse, is given a daily dose of pyrimethamine, which is equivalent to about 0.8-1.2 mg per kg of equine, most preferably about 1.0 mg per kg. The subject is also given, concurrently for the greatest convenience, an amount per day of a sulfonamide, which is equivalent to about 15-30 mg per kg of equine, most preferably about 20 mg per kg. Once daily administration of the active ingredients, say every morning on an empty stomach, for at least about 3 months, preferably about 90-180 days, is sufficient to treat the infection. In some cases, however, the treatment regimen can last indefinitely, sometimes for the remaining life of the horse. For ease of administration, the therapeutic composition may be given orally (that is, by mouth).
It should be apparent that an object of the present invention is the treatment of equine protozoal myeloencephalitis or EPM by providing a veterinary composition comprising pyrimethamine and a sulfonamide, provided that the composition does not also include significant amounts of trimethoprim. By xe2x80x9cnot also include significant amounts of trimethoprimxe2x80x9d means that any trimethoprim present in the veterinary composition should not reach any known therapeutic levels of trimethoprim, certainly not reaching an amount by weight, which is equivalent to about two-thirds the weight of the active sulfonamide, preferably less than about one-half and more preferably less than about one-third of the sulfonamide. Most preferably, the veterinary composition of the present invention (or the instant method of treatment of EPM) is substantially free of trimethoprim.
Convenient dosage formulations of the present invention are also contemplated, including solid and liquid forms, and unit dosage forms comprising about 0.3-0.7 gm pyrimethamine and about 6-14 gm sulfonamide, preferably about 0.5 gm pyrimethamine and about 10 gm sulfonamide.
These and other objects of the invention will become apparent to those of ordinary skill in the art, especially after consideration of the following detailed description of the preferred embodiments.
The instant invention involves, in a preferred embodiment, the administration of an oral suspension, containing pyrimethamine and a sulfonamide, such as sulfadiazine, designed to overcome the shortcomings of currently available treatments of EPM and to provide a more effective drug combination for horses and other equines infected with an organism of the genus Sarcocystis. As previously mentioned, pyrimethamine may be given in a preferred dose of about 1 mg/kg equine with a sulfonamide in a dose of about 15 to 30 mg/kg equine, preferably 20 mg/kg.
It has been found that a 30 mL dose of an oral suspension (such as that described, below) daily on an empty stomach will provide adequate dosing for the treatment of EPM that neither pyrimethamine nor sulfadiazine can treat alone. Since EPM is a protozoal infection of the central nervous system, the appropriate drug combination must penetrate to the CNS and treat the protozoal infection.
In general, the composition to be administered may comprise about 10-20 gm pyrimethamine and about 150-600 gm sulfonamide, preferably 200-400 gm sulfonamide, per liter of composition. The liquid or solid composition may be prepared in unit dosage form depending upon the minimum size of the equine. Such unit dosage forms comprise a relative weight ratio of pyrimethamine to sulfonamide in a range of about 1:15 to about 1:30, preferably about 1:20. Typically, the unit dosage forms contain about 0.3-0.7 gm of pyrimethamine and about 6-14 gm of sulfonamide, most preferably 0.5 gm pyrimethamine and about 10 gm sulfonamide.
The present invention has been found to successfully inhibit the growth of the organism Sarcocystis neurona in equines, such as mules, ponies and horses. It has been observed that the preferred sulfonamide, sulfadiazine, has resulted in better than about a 70% rate of efficacy. In fact, the effectiveness of the present compositions and methods appears to be at least about 80% or 90% of the cases, and probably even higher.
In line with the foregoing, it is within the contemplation of the present invention to employ compositions utilizing one or more sulfonamides and/or pyrimidine derivative in treating EPM. Examples of other suitable pyrimidine derivatives include, but are not limited to, 2,4-diamino-5-benzylpyrimidines substituted in the phenyl ring, such as 2,4,diamino-5-(3,5-dimethoxy-4-methoxyethoxybenzy)-pyrimidine(tetroxoprim) and 2,4-diamino-5-(3,5,dimethoxy-4-methylthiobenzyl)-pyrimidine(metioprim). Still other useful pyrimidines may be 2,4-diamino-5-(4-bromo-3,5-dimethoxybenzyl)-pyrimidine, 2,4-diamino-5-[3,5-diathoxy-4-(pyrrol-1-yl)-benzyl]-pyrimidine, 2,4-diamino-5-(3,5-dimethoxy-4-dimethylaminobenzyl)-pyrimidine, 2,4-diamino-5-(3,4-dimethoxybenzyl)-pyrimidine (diaveridine) and 2,4-diamino-5-(2-methyl-4,5-dimethoxybenzyl)-pyrimidine.
In a similar manner, numerous sulfonamides may be suitably utilized in the present invention, including those previously disclosed in U.S. Pat. No. 5,273,970, whose disclosure is incorporated in its entirety by reference herein. In particular, those sulfonamides having a dinitrogen aromatic ring are especially useful, such as acetyl sulfamethoxypyrazine, N-2-formylsulfisomidine, salazosulfadimidine, sulfachlorpyridazine, sulfadimethoxine, sulfadoxine, sulfalene, sulfamerazine, sulfameter, sulfamethazine, sulfamethomidine, sulfamethoxypyridazine, sulfaperine, sulfaphenazole, sulfapyrazine and sulfisomidine.
Still other sulfonamides known to be useful in veterinary applications can be adventitiously used, including phthalylsulfacetamide, phthalylsulfathiazole, succinylsulfathiazole, sulfabenzamide, sulfacetamide, sulfaethidole, sulfaguanidine, sulfamethizole, sulfamethoxypyridazine, sulfanilamide, sulfanilamidomethanesulfonic acid triethanolamine salt, sulfanitran, sulfapyridine, sulfathiazole and sulfisoxazole. The above-mentioned sulfonamides may be used in place of the preferred sulfadiazine or in addition thereto.
The present compositions may be administered by routes well known to those skilled in the veterinary and formulation sciences. Therefore, although the pyrimethamine and sulfadiazine, for example, are conveniently administered orally, depending on the circumstances, the pharmaceutical composition may be administered parentally, topically, intramucosally (e.g., intravaginally), or by other routes known to those skilled in this art.
Compositions suitable for oral administration, in addition to suspensions, include tablets, capsules, gels, pastes, boluses, or preparations in the form of powders, granules, or pellets. Preferred orally administered compositions include suspensions and tablets.
Alternatively, the composition may be administered parenterally by sub-cutaneous, intramuscular, intraperitoneal, or intravenous injection, or by implantation. The composition can be given as an intramammary injection whereby a suspension or solution is introduced into the udder.
Pharmaceutically acceptable carriers present in the compositions of the present invention are materials recommended for the purpose of administering the medicament. These may be liquid, solid, or gaseous materials, which are otherwise inert or medically acceptable and are compatible with the active ingredients. The same applies for any added excipients.
For oral administration, fine powders or granules will contain diluting agents, for example, calcium carbonate, calcium phosphate, mineral carriers, etc., disbursing and/or surface active agents, for example, polysorbates, and may be presented in a drench, in water or in a syrup, in a bolus, paste, or in capsules or sachets in the dry state or in a non-aqueous suspension, or in a suspension in water or syrup. Where desirable or necessary, preserving, suspending, thickening or emulsifying agents can be included. If intended for oral use, a bolus will be provided with retention means to inhibit regurgitation. For example, it may be weighed with a heavy density materials such as iron or tungsten or the like or may be retained by its shape, for example, by wings which spring after administration. Boluses may contain disintegrating agents such as maize starch or calcium or sodium methylcelluloses, hydroxypropylmethylcellulose, guar based vegetable gums, sodium alginates or sodium starch glycolates; granulating or binding agents, such as starch in the form of mucilage, starch derivatives, such as methylcellulose, calcium stearate, talc, gelatin or polyvinylpyrrolidone; and/or lubricating agents, such as magnesium stearate or stearic acid.
Other compounds which may be included are for example, medically inert ingredients, e.g. solid and liquid diluents, such as starch or calcium phosphate for tablets, boluses or capsules; olive oil or ethyl oleate for soft capsules; and water or vegetable oil for suspensions or emulsions; lubricating agents such as talc or magnesium stearate; gelling agents such as colloidal clays; thickening agents such as gum tragacanth or sodium alginate; dedusting agents such as liquid paraffin, fixed oils and surfactants and other therapeutically acceptable accessory ingredients, such as humectants, preservatives, buffers, and anti-oxidants, which are useful as carriers in such formulations. When desired, other medicaments and/or nutrients, such as vitamins or the like, unless contraindicated, may also be included.
It is also to be understood that while the preferred formulation is administered once a day, it may be given two or more times a day, depending on the circumstances. It should be understood that while it is convenient to administer the pyrimidine and sulfonamide concurrently, they can be given separately with equal efficacy. However, the other optimum conditions, such as the administration of the drug combination on an empty, preferably at least about one hour before the horse is fed should be observed.
A further appreciation of the invention may be gleaned from the following specific examples. These specific examples are provided for illustration only and are not to be regarded as restricting the invention in any way.

Treatment of equine protozoal myeloencephalitis


A method for treating a micro-roughened metal surface to improve bonding between the metal surface and a polymer material. The method involves post-treating the micro-roughened conversion coated metal surface with an aqueous wetting agent composition after having formed the micro-roughened conversion coated metal surface with an adhesion promotion composition. The method can be employed in the circuit board industry to improve bonding between layers in multilayer circuit boards.

1. Field of the Invention
The present invention is directed to a method of improving adhesion between metal and polymeric materials. More specifically, the present invention is directed to a method of improving adhesion between metal and polymeric materials by treating the metal with an aqueous wetting agent composition following an adhesion promotion step.
2. Background
Printed circuits containing one or more circuitry innerlayers are in prominent use today as demand increases for further and further weight and space conservation in electronic devices.
In a fabrication of a multilayer printed circuit, patterned circuitry innerlayers are first prepared by a process in which a copper foil-clad dielectric substrate material is patterned with resist in the positive image of the desired circuitry pattern, followed by etching away of the exposed copper. Upon removal of the resist, there remains the desired copper circuitry pattern.
One or more circuitry innerlayers of any particular type or types of circuitry pattern, as well as circuitry innerlayers which might constitute ground planes and power planes, are assembled into a multilayer circuitry by interposing one or more partially-cured dielectric substrate material layers (so called xe2x80x9cpre pregxe2x80x9d layers) between the circuitry innerlayers to form a composite of on alternating circuitry innerlayers and dielectric substrate material. The composite is then subjected to heat and pressure to cure the partially cured substrate material and achieve bonding of circuitry innerlayers thereto. The cured composite will then have a number of through holes drilled therethrough, which are then metallized to provide a means for conductively interconnecting all circuitry layers. In the course of the through hole metallizing process, desired circuitry patterns will also typically be formed on the outer facing layers of the multilayer composite.
An alternate approach to the formation of a multilayer printed circuit board is through additive or surface laminar circuitry techniques. These techniques begin with a non-conductive substrate, upon which the circuit elements are additively plated. Further layers are achieved by repeatedly applying an imageable coating upon the circuitry and plating further circuit elements upon the imageable coating.
It has long been known that the strength of the adhesive bond formed between the copper metal of the circuitry innerlayers and the cured pre-preg layers, or other non-conductive coatings, in contact therewith leaves something to be desired, with the result that the cured multilayer composite or the coating is susceptible to delamination in subsequent processing and/or use. In response to this problem, the art developed the technique of forming on the copper surfaces of the circuitry innerlayers (before assembling them with pre-preg layers into a multilayer composite) a layer of copper oxide, such as by chemical oxidation of the copper surfaces. The earliest efforts in this regard (so-called xe2x80x9cblack oxidexe2x80x9d adhesion promoters) produced somewhat minimal improvement in the bonding of the circuitry innerlayers to the dielectric substrate layers in the final multilayer circuit, as compared to that obtained without copper oxide provision. Subsequent variations on the black oxide technique included methods wherein there is first produced a black oxide coating on the copper surface, followed by post-treatment of the black oxide deposit with 15% sulfuric acid to produce a xe2x80x9cred oxidexe2x80x9d to serve as the adhesion promoter, such as disclosed by A. O. Osborne, xe2x80x9cAn Alternate Route To Red Oxide For Inner Layersxe2x80x9d, PC Fab. August, 1984, as well as variations involving direct formation of red oxide adhesion promoter, with varying degrees of success being obtained. U.S. Pat. Nos. 4,409,037 and 4,844,981 to Landau, the teachings both of which are incorporated herein by reference in their entirety, report certain oxides formed from relatively high chlorite/relatively low caustic copper oxidizing compositions, and producing substantially improved results in circuitry inner layer adhesion.
As earlier noted, the assembled and cured multilayer circuit composite is provided with through-holes which then require metallization in order to serve as a means for conductive interconnection of the circuitry layers of the circuit. The metallizing of the through-holes involves steps of resin desmearing of the hole surfaces, catalytic activation, electroless copper depositing, electrolytic copper depositing, and the like. Many of these process steps involve the use of media, such as acids, which are capable of dissolving the copper oxide adhesion promoter coating on the circuitry innerlayer portions exposed at or near the through hole. This localized dissolution of the copper oxide, which is evidenced by formation around the through-hole of a pink ring or halo (owing to the pink color of the underlying copper metal thereby exposed), can in turn lead to localized delamination in the multilayer circuit. The art is well aware of this xe2x80x9cpink ringxe2x80x9d phenomenon, and has expended extensive effort in seeking to arrive at a multilayer printed circuit fabrication process which is not susceptible to such localized delamination. One suggested approach has been to provide the adhesion promoting copper oxide as a thick coating so as to retard its dissolution in subsequent processing simply by virtue of shear volume of copper oxide present. This turns out to be essentially counter-productive, however, because the thicker oxide coating is inherently less effective as an adhesion promoter per se. Other suggestions relating to optimization of the pressing/curing conditions for assembling the multilayer composite have met with only limited success.
Other approaches to this problem involve post-treatment of the copper oxide adhesion promoter coating prior to assembly of circuitry innerlayers and pre-preg layers into a multilayer composite. For example, U.S. Pat. No. 4,775,444 to Cordani reports a certain process in which the copper surfaces of the circuitry innerlayers are first provided with a copper oxide coating and then contacted with an aqueous chromic acid solution before the circuitry innerlayers are incorporated into the multilayer assembly. The treatment is said to stabilize and/or protect the copper oxide coating from dissolution in the acidic media encountered in subsequent processing steps (e.g., through-hole metallization), thereby minimizing pink ring/delamination possibilities.
U.S. Pat. No. 4,642,161 to Akahoshi et al., U.S. Pat. No. 4,902,551 to Nakaso et al., and U.S. Pat. No. 4,981,560 to Kajihara et al., and a number of references cited therein, relate to certain processes in which the copper surfaces of the circuitry innerlayers, prior to incorporation of the circuitry innerlayers into a multilayer circuit assembly, are first treated to provide a surface coating of adhesion-promoting copper oxide. The copper oxide so formed is then reduced to metallic copper using particular reducing agents and conditions. As a consequence, the multilayer assembly employing such circuitry innerlayers will not evidence pink ring formation since there is no copper oxide present for localized dissolution, and localized exposure of underlying copper, in subsequent through-hole processing. As with other techniques, however, processes of this type are suspect in terms of the adhesion attainable between the dielectric substrate layers and the metallic copper circuitry innerlayers. This is particularly so in these reduction processes since the circuitry bonding surface not only is metallic copper, but also presents the metallic copper in distinct phases (i.e., (1) copper-from-reduction-of-coppper oxide over (2) copper of the copper foil) which are prone to separation/delamination along the phase boundary.
U.S. Pat. Nos. 4,997,722 and 4,997,516 to Adler report formation of a certain copper oxide coating on the copper surfaces of circuitry innerlayers, followed by treatment with a specialized reducing solution to reduce the copper oxide to metallic copper. Certain portions of the copper oxide apparently may not be reduced all the way to metallic copper (being reduced instead to hydrous cuprous oxide or cuprous hydroxide), and those species are thereafter dissolved away in a non-oxidizing acid which does not attack or dissolve the portions already reduced to metallic copper. As such, the multilayer assembly employing such circuitry innerlayers will not evidence pink ring formation since there is no copper oxide present for localized dissolution, and localized exposure of underlying copper, in subsequent through-hole processing. Here again, however problems can arise in terms of the adhesion between the dielectric layers and metallic copper circuitry innerlayers, firstly because the bonding surface is metallic copper, and secondly because the metallic copper predominately is present in distinct phases (i.e., (1) copper-from-reduction-of-copper oxide over (2) copper of the copper foil), a situation prone to separation/delamination along the phase boundary.
U.S. Pat. No. 5,289,630 to Ferrier et al., the teachings of which are incorporated herein by reference in their entirety, reports a certain process whereby an adhesion promotion layer of copper oxide is formed on the circuit elements followed by a controlled dissolution and removal of a substantial amount of the copper oxide in a manner which does not adversely affect the topography.
PCT Application No. W096/19097 to McGrath, the teachings of which are incorporated by reference herein in their entirety, reports a certain process for improving the adhesion of polymeric materials to a metal surface. The process discussed involves contacting the metal surface with an adhesion-promoting composition comprising hydrogen peroxide, an inorganic acid, a corrosion-inhibitor and a quaternary ammonium surfactant.
U.S. Pat. No. 5,869,130, to Ferrier entitled xe2x80x9cProcess For Improving Adhesion of Polymeric Materials to Metal Surfacesxe2x80x9d reports a certain process for improving the adhesion of polymeric materials to a metal surface, especially copper or copper alloy surfaces in the production of multilayer printed circuits. The described process provides for contacting the metal surface with a certain adhesion-promoting composition comprising (a) an oxidizer; (b) an acid; (c) a corrosion inhibitor; (d) a source of halide ions; and (e) optionally, a water soluble polymer. That process is said to provide enhanced adhesion between the metallic and polymeric surfaces (i.e. the circuitry and the intermediate insulating layer), while eliminating or minimizing pink ring and operating economically, as compared to above noted conventional processes.
However, it has been found that the use of acidic peroxide treatment solutions, while giving good peel strength and stability of copper laminated to fiberglass filled resin, allows the occurrence of sore flaws on further processing of the laminated board to create a finished printed circuit board. Thus, with some resin systems, particularly lower Tg materials, drilling removes a small quantity of organic material from the surface of the etch treated copper at the point where the drill intersects with the copper layer; this phenomenon is called xe2x80x9cwedgexe2x80x9d. Further processing the drilled board through the chemical steps of preparing and plating the board created a small area at the treated copper surface around the drilled hole where the coating is attacked and removed, creating a phenomenon called xe2x80x9cpink ringxe2x80x9d. This area of pink ring is much smaller than the pink ring observed in standard oxide processing to prepare copper surfaces for lamination. Nevertheless, in this area of attack small areas of resin contracting from the copper surface can be observed after floating the board in molten solder. Although these areas of resin contraction (called xe2x80x9cresin voidsxe2x80x9d) may not be sufficient cause for rejection of the board they are still a concern.
In particular, it has been found that these wedge, pink ring and resin void flaws can be greatly reduced or eliminated by processing the board treated with these acidic peroxide treatment solutions through a strongly alkaline post treatment, followed by rinsing and drying.
U.S. Pat. No. 6,020,029 to Ferrier et al. reports an acidic peroxide, adhesion promotion composition containing an oxidizer, an acid, a corrosion inhibitor, optionally a source of halide ions and optionally a water soluble polymer. Preferably, the water-soluble polymer is not a wetting agent or surfactant, but a water soluble homopolymer or copolymer of low molecular weight. The composition is applied to a metal surface. After the acidic peroxide solution is applied to the metal, the metal is post-treated with a strong alkaline solution followed by rinsing with water. After the metal is so post-treated, a polymeric material is bonded to the metal surface. The ""029 patent alleges that the combination of the halide and water soluble polymer in the acidic peroxide composition provide the best bonding results between the metal surface and the polymeric material.
WO 00-02426 discloses another method for addressing bond integrity between a metal surface and a polymeric coating. The method reported in WO 00-02426 to convert cupric-based organometallic compounds into cuprous-based organometallic conversion coatings to improve bonding integrity. The process is achieved by reduction and/or by partial dissolution of the organometallic coating, and optionally applying a copper oxidation inhibitor. Reducing agents employed include aminoboranes and dissolution agents include cupric ion chelators, organic or inorganic acids and their salts. Copper oxidation inhibitors include azole derivatives, including halogen substituted derivatives thereof. Cationic, amphoteric, anionic and/or non-ionic surface active agents may be included in the composition to enhance the effectiveness of the composition.
Although there are numerous methods of improving, the bonding integrity between a metal surface and a polymeric material, there is still a desire and a need in the circuit board industry to increase adhesion between a metal surface and a polymeric material. Many of the above disclosed methods employ treatment solutions that are acidic or alkaline and cause tile formation of nooks and crannies on the metal surface. However, none of the above-disclosed methods attempt to exploit the rough metal surface to further enhance bonding between the metal and the polymeric material. Accordingly, there is a need for a process that exploits the surface roughness of the metal to improve the adhesive properties between the metal and polymeric material.
The invention provides new methods for treating metal surfaces, such as a copper surface of a copper-clad printed circuit board laminate. These methods can provide significantly improved peel strengths of an applied polymer laminate, such as epoxy resin and the like.
More particularly, preferred methods of the invention include treatment of a metal surface with an adhesion promotion composition followed by treatment with a wetting agent composition. Thereafter, a polymer composition (laminate) is applied to the metal surface.
Without being bound by any theory, the aqueous wetting agent composition preferably can provide a micro-roughened (e.g. nooks and crannies) surface, thereby rendering the metal surface more accessible to contact with a polymeric material to be coated on the metal surface. After the treated metal surface is post-treated with the aqueous wetting agent composition, the polymeric material is placed on the surface of the metal to form a high integrity bond between the metal surface and the polymer material. Advantageously, the method and wetting agent composition of the present invention provide for improved adhesion between a metal surface and a polymeric material as compared with known adhesion promoting processes. Accordingly, the adhesion between the metal surface and the polymeric material is such that multilayer circuit boards prepared using the method of the present invention may be readily handled by workers without concern of the polymeric material peeling from the metal surface.
Importantly, the aqueous wetting composition post-treatment of the present invention prolongs the life of the final product. Multilayer circuit boards post-treated in accordance with the present invention and installed in electronic equipment do not delaminate as readily over time as multilayer circuit boards that were not post-treated. Thus the electronic products have an improved life.
Also, the post-treatment method of the present invention may be employed with many different adhesion promotion treatments to further improve adhesion between a metal surface and a polymeric material. Thus the process of the present invention is a readily available means of improving the adhesion promoting methods known in the circuit board industry.
An objective of the present invention is to provide a means of improving the adhesion integrity between a metal surface and a polymeric material.
Another objective is to provide an improved peel strength between a metal surface and a polymeric coating.
An additional objective of the present invention is to provide a multilayer circuit board that can readily be processed through various manufacturing steps without the concern of the polymeric coating separating from the metal surface.
A further objective of the present invention is to provide a method of improving adhesion between a metal surface and a polymeric material that can be employed to improve known adhesion methods.
Additional objectives and advantages of the present invention will be apparent to those of skill in the art after reading the following description of the invention and the appended claims.
As discussed above, the invention includes processes for improving the adhesion between a metal surface and a polymeric material by treating the metal surface with an adhesion promotion composition followed by contacting the treated metal surface with an aqueous wetting agent composition.
The aqueous composition is employed as a post treatment step after treating a metal surface with an adhesion promoting composition. The adhesion promoting composition preferably can produce a micro-roughened surface, i.e. nooks and crannies on a metal substrate. While not being bound by any particular theory or mechanism, it is believed that post-treatment of the metal surface with the aqueous wetting agent composition permits the wetting agents to penetrate the nooks and crannies to reduce surface tension between the nooks and crannies and the polymer material and/or planarize the metal surface. A wetting agent within the scope of the present invention is an agent in a suitable quantity such that the agent provides contact between a polymeric material and the nooks and crannies of a micro-roughened metal surface. Preferably, the aqueous wetting agent composition contains the wetting agent and water without additional additives.
The present process is particularly suited to the manufacture of multilayer printed circuit boards. Thus, in this application, the metal circuitry (usually copper) of the innerlayers is treated with an adhesion-promoting composition. After adhesion promotion treatment, optionally followed by water rinsing, the innerlayers are post-treated with an aqueous wetting agent composition. Optionally, another rinsing step may be employed before applying the polymer to the metal. The innerlayers are bonded together with polymeric materials such as pre-pregs or imageable dielectrics, resulting in the multilayer printed circuit board.
The metal surface to be treated may comprise a variety of metals such as copper, nickel, iron and alloys of each of the foregoing. However, the process of the invention produces the best results when the metal surfaces comprise copper or copper alloys. The polymeric material may be a variety of polymeric materials including pre-preg materials, imageable dielectrics, photoimageable resins, soldermasks, adhesives or polymeric etch resists.
Any suitable water miscible wetting agent may be employed to practice the present invention as long as the agent falls within the scope of the definition of wetting agent as defined above. Examples of suitable water miscible, wetting agents include, but are not limited to, glycols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, isobutylene glycol and the like.
Suitable glycol ethers include, but are not limited to, water miscible glycol ethers such ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and the like. Other suitable glycol ethers, but less preferred, are glycol mono(C1-C6)alky ethers and glycol di(C1-C6)alkyl ethers, such as but not limited to (C1-C20)alkanediol (C1-C6)alkyl ethers and (C1-C20)alkanediol di(C1-C6)alkyl ethers. The acetates of the above disclosed glycol ethers also may be employed.
Suitable poly(alkylene oxide) polymers, also useful as wetting agents, include, but are not limited to, poly(propylene oxide), poly(ethylene oxide), polyethylene oxide/propylene oxide), polypropylene glycol)(meth)acrylates, polypropylene glycol) alkyl ether(meth)acrylates, poly(propylene glycol) phenyl ether(meth)acrylates, poly(propylene glycol) 4-nonylphenol ether(meth)acrylates, poly(ethylene glycol)(meth)acrylates, poly(ethylene glycol) alkyl ether(meth)acrylates, poly(ethylene glycol) phenyl ether methacrylates, polypropylene/ethylene glycol) alkyl ether(meth) acrylates and mixtures thereof. The di- and tri-(alkylene oxide) polymers also may be employed.
Additional suitable wetting agents that can be employed include ethoxylated alkylphenols, fatty acid ethoxylates, fatty alcohol ethoxylates, ethylene oxide/propylene oxide (EO/PO) copolymers and the like. The ethylene oxide/propylene oxide copolymers are obtainable from BASF, Wyandotte Michigan, and are known by the tradenames Pluronics(copyright) and Tetronics(copyright).
The preferred wetting agents are the glycols, such as polyethylene glycol, and the ethylene oxide/propylene oxide copolymers or Pluronics(copyright).
The wetting agents are employed in an aqueous composition in amounts sufficient to permit a polymeric material to contact the nooks and crannies of a metal surface. The amount of wetting agent in the composition ranges from about 0.5% by weight to about 30% by weight, preferably from about 1% by weight to about 15% by weight of the composition, most preferably from about 1.5% to about 5%. Preferably, the aqueous wetting agent composition consists essentially of the wetting agent and water.
As mentioned above, any suitable adhesion promoting treatment process can be employed provided that the adhesion promoting composition produces a micro-roughened conversion-coated surface upon the metal. Such surfaces are particularly suited to bonding with polymeric material in contrast to non-treated metal surfaces. Such adhesion promoting baths may contain an oxidizer, an acid and a corrosion inhibitor. Additional components and modifications to such adhesion promoting compositions may be employed as discussed below. Such adhesion promoting compositions have pH ranges from about 2.0 to as high as about 13.0.
The oxidizer used in the adhesion-promoting composition may comprise any oxidizer that is capable of oxidizing the metal surface in the matrix of the adhesion-promoting composition. Hydrogen peroxide and persulfates are particularly preferred oxidizers for use in the process of the invention, with hydrogen peroxide being the most preferred oxidizer. The concentration of the oxidizer in the adhesion-promoting composition may range from at least about 0.01% by weight based on the total weight of the composition to as high as about 60.0% by weight. Preferably, the hydrogen peroxide is present from about 0.1 to about 20% by weight, more preferably from about 0.5% to about 10%, and most preferably from about 1% to about 5%. Hydrogen peroxide is commercially available as, e.g., 35% by weight in water.
The adhesion-promoting compositions optionally may contain a stabilizing agent for hydrogen peroxide. Any suitable stabilizing agent for hydrogen peroxide may be used. Examples include, but are not limited to, dipicolinic acid, diglycolic acid and thiodiglycolic acid, ethylene diamine tetraacetic acid and its derivatives, magnesium salts of an aminopolycarboxylic acid, sodium silicate, phosphates and sulphonates. Stabilizers are added its amounts of from about 0.001% and preferably at least about 0.005% by weight of the adhesion promotion composition. More preferably, the concentration of the stabilizing agent varies between about 0.5 to about 5.0% by weight of the composition.
The acid utilized in the adhesion-promoting composition may be any acid that is stable in the matrix. Preferred acids are inorganic acids and may be employed as a singe acid or a mixture of acids. A variety of inorganic acids may be used including, but not limited to, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid and mixtures thereof. Sulfuric acid, phosphoric acid or mixtures thereof is especially preferred. When a mixture of inorganic acids is used, the acids may be combined in any suitable ratio. A ratio of from about 99:1 to about 1:99, and preferably from about 75:25 to about 25:75 may be employed. When a mixture of sulfuric acid and phosphoric acid are used, preferably sulfuric acid is used in major amounts and phosphoric in minor amounts. The concentration of the acid in the adhesion-promoting composition may range from about 5 to about 360 grams per liter, preferably from about 70 to about 110 grams per liter.
The corrosion inhibitor used in the adhesion-promoting composition is a compound that effectively reacts with the metal surface to form a protective complex layer. Preferred corrosion inhibitors are pyrroles, azoles, oxazoles, thiazoles, pyrazoles, triazoles, benzotriazoles, tetrazoles, tolyltriazoles, hydroxy-substituted azole compounds, imidazoles, benzimidazoles such as 5-methylbenzimidazole, 2-bromobenzyl benzimidazole, 2-chlorobenzyl benzimidazole, 2-bromophenyl benzimidazole, 2-chlorophenyl benzimidazole, 2-bromophenyl benzimidazole, 2-chloroethylphenyl benzimidazole and 2-undecyl-4-methylimidazole, or mixtures thereof. Hydroxy-substituted azole compounds may have more than one hydroxy substituent and may be further substituted, such as with a (C1-C6)alkyl, (C1-C6)alkoxy, halogen and the like. Suitable hydroxy-substituted azole compounds include, but are not limited to, hydroxy-substituted triazoles and hydroxy-substituted tetrazoles. 1-Hydroxybenzotriazole is a preferred hydroxy-substituted triazole. Examples of suitable benzotriazoles include, but are not limited to, benztriazole, carboxybenzoxtriazole and mixtures thereof. The corrosion inhibitors are available from a variety of commercial sources and may be employed without further purification. The concentration of the corrosion inhibitor in the adhesion-promoting composition may range from about 0.1 to about 20% by weight based on the total weight of the composition, preferably from about 0.2 to about 1% by weight, and most preferably from about 0.3 to about 0.6% by weight.
Optionally, a source of halide ions may be employed in the adhesion-promoting compositions. Any suitable source of halides may be employed as long as the source provides halide ions in the matrix of the adhesion-promoting composition. Examples of suitable sources of halide ions are alkali metal salts such as sodium chloride or potassium chloride, oxohalides such as sodium chlorate or potassium chlorate, or halide bearing mineral acids such as hydrochloric acid. The most preferred sources are halide sources that are free of surfactant groups, such, as tetraalkyl ammonium halides, such as tetraalkyl ammonium chloride, tetrabutyl ammonium chloride and mixtures thereof. The concentration of the source of halide ions in the adhesion-promoting composition may range from about 1 to about 50 ppm. When chloride is employed, the chloride ion is present in amounts of preferably from about 1 to about 8 ppm, most preferably from about 4 to about 7 ppm.
Optionally, the adhesion-promoting composition also comprises a water soluble polymer. The water soluble polymer is a polymer of ethylene oxide, an ethylene oxide-propylene oxide copolymer, polyethylene glycols, polypropylene glycols or polyvinyl alcohols. Among the most preferred are the polymers of ethylene oxide, or polyethylene glycols sold by the Union Carbide Company under the tradename Carbowax. Particularly useful are the ethylene oxide polymers or ethylene oxide-propylene oxide copolymers sold by the BASF company under the Pluronic tradename. The concentration of the water soluble polymer in the adhesion-promoting composition can range from 1 to 15 grams per liter, but is preferably from 3 to 6 grams per liter.
The adhesion promotion compositions of the present invention preferably are free of surfactants.
An additional component that may be added to the adhesion composition or bath is a non-surfactant amine or a quaternary ammonium compound. The term amine as used herein is defined as a lower aliphatic, cycloaliphatic or aromatic amine, i.e. a primary, secondary or tertiary amine having substitution by groups containing from 1 to about 8 carbon atoms. The term quaternary ammonium compound as used herein is inclusive of lower aliphatic, cycloaliphatic or aromatic amine compound. Each term preferably excludes from its scope materials having fatty substitution or other surfactant groups. Each substituent on the amine may be aliphatic, cycloaliphatic or aromatic and each of such substituents may be further substituted with groups such as carboxyl, nitro, sulfonyl, hydroxyl, and the like. Exemplary amines include methyl amine, dimethylamine, trimethylamine, ethylamine, triethylarnine, tripropylamine, isopropylamine, triallylamine, n-utylamine, t-butylamine, n-amylamine, cyclohexylamine, dicyclohexylamine, and the like. Exemplary quaternary amine or ammonium compounds include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and dimethyl-diethylammonium hydroxide, tetramethylammonium chloride, tetraethylammoium chloride and dimethyl-dimethylammonium chloride. The amines compounds are used in a concentration of from about 0.01% by weight to about 2.5% by weight and more preferably, in a concentration of from about 0.1 to about 1.0% by weight.
Prior to adhesion-promotion and the post-treatment step, the metal surface, particularly copper, or a copper alloy surface, preferably is cleaned by mechanical or chemical cleaning and then contacted with the adhesion-promotion composition. The metal surface can be treated with the adhesion-promoting composition in a variety of ways, including immersion, spray, or flood. The temperature of the adhesion promotion composition during treatment preferably does not exceed 75xc2x0 C. and more preferably, is at a temperature varying between about 20xc2x0 C. to about 50xc2x0 C. Contact time is at least about 1 second and preferably between about 5 seconds and about 2 minutes though the maximum contact time may be up to about 10 minutes. A contact time of about 1 minute or less is particularly preferred.
After the metal surface is treated with the adhesion-promoting composition, the metal is spray-coated or dip-coated or coated by any suitable means in the art with the aqueous wetting agent composition. Such coating methods include both vertical and horizontal methods and apparatus. Contact time between the treated metal and the aqueous wetting agent composition ranges from about 1 second to about 1 minute, preferably, between about 10 to about 30 seconds. Preferably, the post-treatment is done at a temperature of from about 18xc2x0 C. to about 22xc2x0 C. (room temperature). The post-treatment process may be performed at higher temperatures, however, there is no advantage to performing the process at temperatures above room temperature. Optionally, the treated metal may be rinsed with water prior to post-treatment and/or prior to placing the polymer material on the metal surface.
The polymer material may be placed on the metal surface to form a bond with the metal surface by any suitable method employed in the art. Mechanical pressure with heat is one method that is very suitable for joining the polymer to the metal surface. The polymer material may be in the forth of a polymeric photoresist, screen-resist solder mask, adhesive material and the like.
In another embodiment of the present invention, the metal surface may be treated with an alkaline solution after the acidic oxidant treatment but prior to the aqueous wetting agent post-treatment. The preferred alkaline solution is an aqueous alkaline solution of alkali metal hydroxide (e.g. sodium hydroxide or potassium hydroxide); alkali metal carbonates (e.g. sodium carbonate or potassium carbonate); alkali metal phosphates (e.g. sodium phosphate or potassium phosphates); or amines or mixtures of those chemicals. The preferred amount of such chemicals in the aqueous solution depends upon the particular chemical-employed as well as the exact use involved. Most preferably an aqueous solution of sodium or potassium hydroxide is used as the alkaline treatment, with the concentration of sodium or potassium hydroxide ranging from 2 to 150 grams per liter, most preferably from 25 to 50 grams per liter. Contact may be made by immersion, conveyorized flood or spray, however conveyorized flood is preferred. Contact time may range from 20 seconds to 10 minutes but 1 to 3 minutes is preferred. Contact temperature may range from room temperature to 85xc2x0 C. but 20xc2x0 C. to 40xc2x0 C. is preferred. This alkaline treatment reduces the number of flaws in the finished laminated product. After the alkaline treatment, the metal surface may be rinsed with water. The treated metal surface is then post-treated with the aqueous wetting agent composition and then the metal surface is bonded to polymeric material by any conventional process.
In another embodiment of the present invention, the adhesion-promoting step may be a process for converting cupric-based organometallic compounds on a copper surface into cuprous-based organometallic conversion coatings. Such a process is achieved by reduction and/or by partial dissolution of the organometallic coating, and optionally applying a copper oxidation inhibitor at the same time.
The reduction and/or dissolution composition contains a reducer and/or dissolution agent, and optionally a copper oxidation inhibitor. Examples of reducers include, but are not limited to, DMAB (dimethylaminoborane), diethylaminoborane, morpholine borane and the like. Other suitable reducers include ammonium, alkali and/or alkaline earth metal borohydrides, hypophosphites, sulfites, bisufites, hydrosulfites, metabisulfites, dithionates, tetrathionates, thiosulfates, thioureas, hydrazines, hydroxylamines, aldehydes (including formaldehyde and glyoxal), glyoxylic acid and reducing sugars. Electric current may be used as well.
Dissolution agents employed may include any of the known cupric ion chelators (complexors), organic or inorganic acids and/or their salts, (or a combination of them,), can be utilized for the present application. Such dissolution agents include, but are not limited to, EDTA (ethylenediamine-tetrancetic acid), HEEDTA, NTA (nitrilotriacetic acid), DTPA (diethylenetriamine pentaacetic acid), DCTA, Quadrol (ethoxylated/propoxylated ethylene diamine derivative available from BASF), organic phosphates (Dequests), organic acids (citric, tartaric, gluconic, glutamic, sulfamic, glycolic, glycino, malic, maleic, salicylic, ascorbic, formic, and the like), inorganic acids (hydrochloric, hydrofluoric, hydrobromic, nitric, chromic acids, and the like), and/or their ammonium hydroxide, pyrophosphates, and the like. Quadrol, EDTA and phosphanates are preferred. Additionally, it may be advantageous to use the dissolution agents with one or more reducing agents.
Suitable oxidation inhibitors or corrosion inhibitors are disclosed above. Cationic, amphoteric, anionic and/or non-ionic surfactants may also be utilized in the adhesion-promoting solution to enhance the effectiveness of the adhesion-promoting solution.
Proper pH, temperature, concentrations of components as well as treatment time are adjusted appropriately as may be desired to promote optimal reduction and/or dissolution. Optimal conditions can be readily determined empirically, i.e. a series of substrates can be treated in accordance with invention under varying conditions and the completed laminated substrates can be tested for adhesion integrity (peel strength) between the metal substrate and the polymer laminate. Preferred conditions also are disclosed in the examples which follow.
After the cupric-based organometallic compounds on the copper surface is converted into cuprous-based organometallic compounds by reduction and/or dissolution, the copper is post-treated with the aqueous wetting composition. The copper surface may be rinsed with water before and/or after the post-treatment followed by placing the polymer material on the copper surface.
The following examples further describes the process and composition of the present invention, however, the examples are not intended to limit the scope of the invention.

Process for treating adhesion promoted metal surfaces