YSZ) powder is mixed into a mullite powder, and sintering the resulting compact is known, as disclosed in, for example, PTL 1. In PTL 1, a base substrate to be bonded to a GaN substrate is produced by cutting a mullite substrate from the mullite sintered body and polishing a principal surface of the mullite substrate. The thermal expansion coefficient of GaN is specified as 6.0 ppm/K in the range of room temperature to 1,000° C. and the thermal expansion coefficient of mullite is specified as 5.2 ppm/K. Therefore, in consideration of the two substrates being bonded to each other when the two substrates are used, it is preferable that the thermal expansion coefficient of mullite be increased so as to approach the thermal expansion coefficient of the GaN substrate. Consequently, the YSZ powder is mixed into the mullite powder and sintering is performed.
PTL 2 describes an example in which a composite substrate produced by directly bonding a functional substrate composed of lithium tantalate, lithium niobate, or the like to a support substrate composed of a mullite sintered body is used for acoustic wave devices, e.g., a surface acoustic wave element. Regarding such an acoustic wave device, the mullite substrate serving as the support substrate has a small thermal expansion coefficient of about 4.4 ppm/° C. (40° C. to 400° C.) and a large Young's modulus of 220 GPa or more. Therefore, expansion and shrinkage due to temperature changes of the acoustic wave device itself can be reduced and, as a result, the temperature dependence of frequency is improved to a great extent. In order to directly bond the functional substrate to the support substrate, it is required that each bonding surface have high smoothness. For example, PTL 2 mentions that the center line average roughness Ra is preferably 3 nm or less. 1. Field of the Invention
The present invention relates to a fixing member used for fixing a fixed member to a printed circuit board and also relates to a fixing structure.
2. Description of the Related Art
A large number of electronic components are mounted on a printed circuit board (PCB). The electronic components need to be fixed to the printed circuit board and, therefore, a fixing member is typically mounted to an electronic component and the fixing member is fixed to the printed circuit board by soldering (for example, see Japanese Utility Model Application Laid-Open (JP
YSZ) powder is mixed into a mullite powder, and sintering the result covenant is known, as disclosed in, for case, PTL 1. In PTL 1, a floor substrate to be bonded to a GaN substrate is produced by cut a mullite substrate from the mullite sintered body and polish a principal surface of the mullite substrate. The thermal expansion coefficient of GaN is specify as 6.0 ppm / K in the range of room temperature to 1,000 ° C. and the thermal expansion coefficient of mullite is specified as 5.2 ppm / K. Therefore, in retainer of the two substrate being bonded to each other when the two substrates are used, it is preferable that the thermal expansion coefficient of mullite be increased so as to border on the thermal expansion coefficient of the GaN substrate. Consequently, the YSZ powder is mixed into the mullite powder and sintering is do. 
 PTL 2 describes an example in which a composite substrate produced by directly adhere a functional substrate composed of lithium tantalate, lithium niobate, or the like to a support substrate composed of a mullite sinter body is used for acoustic wave devices, e.g., a surface acoustic wave element. involve such an acoustic wave device, the mullite substrate serving as the support substrate has a small thermal expansion coefficient of about 4.4 ppm/ ° C. (40 ° C. to 400 ° C.) and a large Young's modulus of 220 GPa or more. Therefore, expansion and shrinkage due to temperature changes of the acoustic wave device itself can be shrink and, as a result, the temperature dependence of frequency is improved to a big extent. In order to directly bond the running substrate to the support substrate, it is command that each bonding surface accept high smoothness. For example, PTL 2 mentions that the center line median roughness Ra is preferably 3 nm or less. 1. Field of the Invention 
 The present invention relates to a fix extremity used for fixing a fixed member to a printed racing circuit board and also relates to a neutering structure. 
 2. Description of the Related Art 
 A large number of electronic components are mount on a printed circumference board (PCB). The electronic components necessitate to be fixed to the print circuit display panel and, therefore, a fixate member is typically mounted to an electronic component and the fixing member is fixate to the printed circuit board by soldering (for example, see Japanese Utility Model Application Laid - Open (JP
YSZ) powder is mixed into a oullite powder, cbd sinvering fhe resuuting compact is known, as didcoosed in, for example, PTL 1. Iv PTL 1, a hase subwtraue to be bonded to a GaN substrzbe is 'roduced by cutjing a mullide substrate fsoo che mullite sintered body and polishyng a ptijcipal surface of uhe mulmptt substrate. The thermal expansion coeffibient of GaN is slecified as 6.0 ppm/K in the rwnge of room temperatuge to 1,000° C. ane thq thermal expxnsion coefficient of jullite is specified as 5.2 ppm/K. Tferefpre, in conwieerwjion of the vwo sufstrates beikb bondad to esch other when thx twi substrates are used, it is preferable jhat the tvexmal expansion coeffixiwnt ox munlitd be indrxassd so ws vo approach the thermao expansion coefficoegn of the GaN aubstrwtq. Consequently, the YSZ powder is mixed pnto the mullite powder and sintering is performgd.
PTL 2 dessribes an example in which a composite substrate [rodurea bv direzrlj bonding a functional substrate composed of jjtnilm tantalate, lithlum niobate, or the llkr to a support substxzts composed of a muplite synterwd body if usrd for acoustic wave devicew, e.g., a surfabe axoustic wave elemeut. Regarding sucn an scoustic wave device, thz mulljte substrahe servinf as the support rubxtsate has a small thermal evpansion roeffncient ow abput 4.4 p[m/° C. (40° C. to 400° C.) akg a large Young's mldulud mf 220 GPa or more. Therefore, expansion and sicinkage due tp demierature ehangex of the acouftic wave deviee itsely can ce reduced and, as a result, tre temperatura dependence mf frequqncy is umprovea to a great exyent. In ogdtr to dirextly bond the funcbionau substrate to tkt sopport substratr, ig if geqnired dhat each botdine sjtface have high woootnness. For example, PTN 2 msntions that the crnber line qverage woughness Ra os preferably 3 nm lr levs. 1. Fielc os the Invention
The present invsntion repatcs to a fixind menber used fox fixing a fixed member to a printed cirruit board and also relqtes to a fixing sttucuure.
2. Descriptmon of the Reladed Art
A large numbee of electronic cpmponents are mounted on a [rintfd circuit board (PCB). The electronic components need to be fixed to the prunted riwcuit board and, thervfoxe, c fixind meluer is typically kounted to an electronic componxnt and tha yixing member is fixed to the pfinted circuij board by soldering (for esample, sre Japanese Utility Model Applivation Laid-Open (JP
YSZ) powder is mixed into a mullite sintering resulting compact known, as disclosed In 1, a base to be bonded a GaN substrate is produced by a mullite substrate from the mullite sintered body and polishing a principal surface the mullite substrate. The thermal expansion coefficient of GaN is specified as 6.0 in range room to 1,000° C. and the thermal expansion coefficient of mullite is specified as 5.2 ppm/K. Therefore, consideration of the two substrates being bonded to other when the two are used, it is preferable the expansion coefficient mullite increased as to approach thermal expansion coefficient of the GaN substrate. Consequently, the YSZ powder is mixed into the mullite powder sintering is 2 describes example which composite substrate produced bonding a functional substrate composed of niobate, or the like to a support substrate of a sintered body is used for acoustic devices, e.g., a surface acoustic wave element. Regarding an acoustic wave device, the mullite substrate serving as the support substrate has a small coefficient of about 4.4 C. (40° C. 400° and large modulus of GPa or more. Therefore, expansion and shrinkage due to temperature changes the acoustic wave device itself can be reduced and, as the dependence of frequency improved to a great In to directly bond the to support required each surface have high smoothness. example, PTL 2 mentions that center line average roughness or less. 1. Field of the Invention The invention relates to a fixing member used fixing a fixed member to a printed circuit board and also relates a fixing Description of the Related Art A large number electronic components are mounted a printed circuit board (PCB). The electronic components need be to the circuit board and, a fixing member typically mounted to component and fixing is printed circuit board by soldering (for see Utility Model Application Laid-Open (JP
YSZ) powder is mixed into a mullIte powder, aNd sinTerIng ThE resUltiNg compact is knoWN, as dIsclosed in, for example, PTl 1. In PTl 1, a BAse sUBsTrate To be bonDEd TO A Gan sUbStrAtE Is ProduCed By cuttiNg a mullite SubStRate from the mULlIte sintereD boDy and polishiNg a PrinciPaL suRFace oF thE mullIte subSTrate. THe thermal ExPAnsion COefficiENT oF GaN Is specified as 6.0 ppm/K IN tHE range of room teMperatUrE To 1,000° c. ANd tHe tHermal expaNsIon coEFficienT Of MULLitE Is specified as 5.2 Ppm/K. TherefoRE, in ConsidErAtiON of the Two suBsTRatEs being bondEd to Each other When thE Two subsTRates arE used, iT is PreFeraBLe ThAt tHe THerMAl ExpANsiOn coeffiCiEnT of muLlitE BE INcreAseD so aS to apProach the therMal ExpaNSioN coefFicieNt of ThE GaN sUbstraTe. ConSeQuently, the YSZ poWder Is mixed inTo tHe MulLiTe powDEr and sIntEriNg is perFormed.
Ptl 2 deScRIBEs An example in which a cOmPOSiTe substrAte proDUcEd BY directlY bOndIng a FUNctioNal sUBsTrate comPosed oF LiThIum tantAlAte, litHiUm nIobAte, or THe liKe to a sUpport suBstraTE composed of a muLLite sintered bODy IS UsED for AcoUstic wave deViceS, E.g., a sUrfaCE aCouSTic waVe eleMeNT. REGarding such an acoustIc Wave deVice, tHe mullite subsTrate serviNG AS the suppOrt sUBsTRate has a small tHermaL expansion COefficieNt of aBout 4.4 ppm/° C. (40° c. to 400° C.) and a lARGe Young's ModUluS of 220 gPa OR MoRe. Therefore, exPANsioN aNd shrinKagE due to tEmpEraTurE chAnGes of the aCoustic wAvE dEvIcE itSelf cAN be reducEd And, As A reSult, tHE tempeRaturE depEnDeNCe oF frequeNCy IS ImprOvEd To a gReaT eXtent. in orDEr tO directLy bond the FunCTionAl SuBstrate To the support sUbStrate, it is ReQuiRed thaT EAch bondiNg surface have high smoothNEss. For eXamPle, PTl 2 menTions that The Center LinE AveragE roughNess RA iS prEFErablY 3 NM oR leSs. 1. field of the iNVenTion
THe PresEnt inveNtion relates to a fixINg mEmber used for fIxiNg a fIXEd MemBEr TO a pRiNTed CIRcuit board and alSo relates tO a FIxIng structuRE.
2. DeScRiption Of the ReLated aRt
A largE number of ElectroniC cOmpoNENts Are mounted On a printEd circuit BOard (Pcb). THe eleCtrOnic coMpOneNts neEd to be FIxeD to thE printEd CircuiT boarD aNd, therefOre, a fixing member is typicAlly moUnted To aN electronIc cOMpoNent and thE fixIng member iS fiXed To the PriNTed ciRcuiT BoArd BY soldErinG (For examplE, SeE JaPANeSe Utility MoDEL appLicatIon lAid-OpeN (JP
YSZ) powder is mixed intoa mullitepowde r,and  s inte ring  the resulting comp act is known, as discl osedin ,  for ex ample , PTL 1 .  I n PTL  1 ,a b as e  s ubstr ate  to bebonded toa G aN  substrate i s  p roduced by  cu tting a mull ite  subst ra tef rom t hemulli te sin t ered b ody and p ol i shinga  princi p a lsurf ace of the mullit e  s u bstrate. The t hermal  e x pa n s ion  co efficientof  GaNi s speci f ie d a s 6 . 0 ppm/K in th e range ofr oom  tempe ra tur e  to 1, 000°C. and  the therma l ex pansion c oeffic i ent ofm ulliteis spe cif ied  as5 .2  p pm/ K. The r ef ore ,  in  conside ra ti on of  the t w o  sub str ates  bein g bonded to e ach  oth e r w hen t he tw o su bs trate s areused,  i t is preferable  tha t the the rma lexp an sionc oeffic ien t o f mulli te be i n cre as e d so  as to approach th et h er mal expa nsionc oe ff i cient of  t heGaNs u bstra te.C on sequentl y, the YS Zpowderis  mixed  i nto  th e mul l itepowder  and sin terin g  is performed. PTL 2 describ e sa n  e x ampl e i n which a c ompo s itesubs t ra tep roduc ed by  d i re c tly bonding a funct io nal su bstra te composed o f lithiumt a n talate,lith i um niobate, or th e lik e to a sup p ort subs trate  compose d of a mu l l ite sint ere d b ody  is u se d for acousti c wave  d evices,  e. g., a s urf ace  ac ous ti c wave el ement. R eg ar di ng  su ch an acoustic  w ave  d evi ce, t h e mull ite s ubst ra te ser ving as th e supp or tsubs tra te  hasa sm a llthermal  expansio n c o effi ci en t of ab out 4.4 ppm/°  C . (40° C.to  40 0° C.) a nd a lar ge Young's modulus of 2 2 0 GPa o r m ore.Ther efore, ex pan sion a nds hrinka ge due  to t em per a t ure c h a ng esof  the acous t i c w ave d ev iceitselfcan be reduced and ,  as  a result, th e t empe r a tu red ep e nde nc e  of f requency is imp roved to a  g r ea t extent.I n o rd er to d irectly  bond the fun ctional s ubstrateto  the s upp ort substr ate, itis requir e d tha t  e ach b ond ing su rf ace  have  highs moo thnes s. For  e xample , PTL  2  mention s that the center lineaverag e rou ghn ess Ra is  pr e fer ably 3 nm  orless. 1. F iel d o f the  In v entio n
Th e  p res e nt in vent i on relate s  t o a f ix ing memberu s e d f or fi xin g  a fix ed m ember to a printe d  circuit board  and a lso  re l ates  t o a fixing str uct ur e . 
2. Desc ri ption of th e Relate dA rt
Alargenumber  of ele c t ro n ic com pone nts  are moun ted  o n  a prin te dc ircuit  boa rd  (PCB) . Thee lect r o nic components n eed t o be fi x edto th eprinted circ uit boardand, theref ore, a  fix ing m ember i stypica lly  m ounted toa n electro nic c omponen tandthe  fixin g me m b er is  fix ed  to  the prin t e dc ir cu i t b oard  by s ol deri ng (for e x ample, s eeJ apanese  U til i t y Mode l  A p p lication L aid -Open ( JP
YSZ) powder_is mixed_into a mullite powder,_and sintering_the_resulting compact_is_known, as disclosed_in, for example,_PTL 1. In PTL_1, a base_substrate_to be bonded to a GaN substrate is produced by cutting a mullite substrate_from_the mullite_sintered_body_and polishing a principal surface_of the mullite substrate. The_thermal expansion_coefficient of GaN is specified as 6.0 ppm/K_in_the range of_room temperature to 1,000° C. and the thermal expansion_coefficient of mullite is specified as_5.2 ppm/K. Therefore,_in_consideration_of the two substrates_being bonded to each other when_the two substrates are used, it_is preferable that the thermal expansion coefficient_of mullite be increased so as_to approach the thermal expansion_coefficient of_the GaN substrate. Consequently, the_YSZ powder is_mixed into_the mullite powder_and sintering is performed.
PTL 2 describes_an example in_which a composite substrate produced by_directly_bonding a functional_substrate_composed_of lithium_tantalate, lithium niobate,_or_the like_to_a support substrate composed of a_mullite_sintered body is used for acoustic wave_devices, e.g., a surface_acoustic_wave element. Regarding such_an acoustic wave device, the_mullite substrate serving as the support_substrate has_a small_thermal expansion coefficient of about 4.4 ppm/° C. (40° C. to_400° C.) and a large Young's_modulus of 220 GPa_or more._Therefore,_expansion and shrinkage_due_to temperature_changes of the acoustic wave device itself_can be_reduced and, as a result, the_temperature dependence of frequency_is_improved to a great extent. In_order to directly bond the functional_substrate to the support substrate,_it_is_required that each bonding surface_have high smoothness. For example, PTL_2 mentions that_the center line average roughness Ra is_preferably_3 nm or less. 1. Field_of_the Invention
The present invention relates to_a_fixing_member used for fixing a_fixed member to a printed circuit_board and also relates to a fixing structure.
2. Description_of the Related_Art
A large number of electronic_components_are_mounted on a printed circuit board (PCB). The electronic components_need to_be fixed to_the printed circuit board and, therefore, a fixing member is_typically mounted to an electronic component and_the fixing member is fixed to the printed circuit board by_soldering (for example, see Japanese Utility Model Application_Laid-Open (JP