1, malata akusunsa kwenikweni

Madzi otentha akasungunuka amasungunuka ndikulowerera pamwamba pazitsulo za PCB kugulitsidwa, kumatchedwa kulumikiza kwazitsulo kapena kulumikiza kwazitsulo. Mamolekyu osakanikirana a solder ndi mkuwa amapanga aloyi watsopano womwe ndi gawo lamkuwa komanso gawo lina la solder. Izi zosungunulira zimatchedwa kulumikiza malata. Amapanga mgwirizano wapakatikati pakati pama PCB osiyanasiyana, ndikupanga chitsulo cholimba chachitsulo. Kapangidwe kazinthu zabwino zama intermolecular ndiye maziko a njira zowotcherera za PCB, zomwe zimatsimikizira mphamvu ndi mtundu wa mfundo zowotcherera za PCB. Tin imatha kudetsedwa pokhapokha ngati mkuwa ulibe zodetsa komanso kanema wa oxide wopangidwa chifukwa cha kuwonekera kwa PCB pamlengalenga, ndipo solder ndi malo ogwirira ntchito amafunika kufikira kutentha koyenera.

2. Mavuto akunja

Aliyense amadziwa bwino momwe madzi alili pamwamba, mphamvu yomwe imasungira madontho amadzi ozizira ozungulira pa mafuta odzozedwa a PCB chifukwa, pakadali pano, kumangiriza komwe kumapangitsa kuti madziwo akhale olimba ndi ochepera kulumikizana kwake. Sambani ndi madzi ofunda ndi zotsekemera kuti muchepetse kukangana. Madzi adzadzaza mbale yachitsulo ya PCB ndikutuluka panja kuti ipange gawo locheperako, lomwe limachitika ngati kulumikizana kukukulira kulumikizana.

Tin-lead solder imagwiranso ntchito kwambiri kuposa madzi, kupangitsa kuti solder izizungulira kuti ichepetse mawonekedwe ake (voliyumu yomweyi, malowo ali ndi malo ocheperako poyerekeza ndi ma geometri ena kuti akwaniritse zofunikira zamagetsi otsika kwambiri). Mphamvu ya kamwazi ikufanana ndi yotsekemera pa mbale yachitsulo ya PCB yokutidwa ndi mafuta. Kuphatikiza apo, mavuto apadziko amadaliranso ukhondo ndi kutentha kwa PCB. Pokhapo pamene guluu wolumikizira mphamvu ndi wokulirapo kuposa mphamvu yakumtunda (kulumikizana), PCB imatha kukhala yolimba kwambiri ndi malata.

3, yokhala ndi tini Angle

Meniscus imapangidwa dontho la solder likayikidwa pamwamba pa PCB yotentha, yokutidwa pafupifupi 35 ° C pamwamba pa eutectic point of solder. Kumlingo wina, kuthekera kwachitsulo pamwamba pa PCB kumata malata kumatha kuyesedwa ndi mawonekedwe a meniscus. Chitsulo sichingagulitsidwe ngati meniscus ili ndi mdulidwe womveka bwino, ikuwoneka ngati madontho a madzi pa mbale yachitsulo ya PCB, kapena imakhala yozungulira. Meniscus yokha ndi yomwe idatambasula mpaka kukula kosakwana 30. Ngodya yaying’ono imakhala ndi kuthekera kwabwino.

4. Mibadwo yazitsulo zamagetsi zamagetsi

Mitengo yolumikizana yamkuwa ndi malata imapanga njere zomwe mawonekedwe ake ndi kukula kwake zimadalira kutalika ndi kutentha kwa kutentha komwe kumalumikizidwa. Kutentha pang’ono panthawi yotsekemera kumatha kupanga mawonekedwe abwino a kristalo, zomwe zimapangitsa PCB kukhala malo owotcherera bwino kwambiri. Kutalika kwanthawi yayitali, mwina chifukwa cha kuwotcherera kwa PCB nthawi yayitali kwambiri, kutentha kwambiri kapena zonse ziwiri, kumabweretsa mawonekedwe amiyala yamiyala yomwe imakhala yolimba komanso yopepuka ndi mphamvu yotsika ya shear.Mkuwa umagwiritsidwa ntchito ngati chitsulo cha PCB, ndipo tini-lead amagwiritsidwa ntchito ngati solder alloy. Mtovu ndi mkuwa sizipanga mtundu uliwonse wazitsulo, koma malata amatha kulowa mumkuwa. Mgwirizano wam’molekyulu pakati pa tini ndi mkuwa umapanga mitundu yazitsulo zachitsulo Cu3Sn ndi Cu6Sn5 pamphambano ya solder ndi chitsulo.

Chitsulo chosanjikiza chachitsulo (n + ε gawo) chikuyenera kukhala chowonda kwambiri. Mu PCB laser kuwotcherera, makulidwe a chitsulo chosanjikiza chachitsulo ndi 0.1mm mgulu la anthu. Mu wave soldering ndi soldering Buku, makulidwe a chomangira cha intermetal mfundo zabwino kuwotcherera kwa PCB ndi oposa 0.5μm. Chifukwa mphamvu kukameta ubweya wa welds PCB amachepetsa monga zitsulo aloyi wosanjikiza makulidwe ukuwonjezeka, nthawi zambiri amayesa kusunga zitsulo aloyi wosanjikiza makulidwe m’munsimu 1μm posunga nthawi kuwotcherera waufupi ngati n’kotheka.

Makulidwe a chitsulo chosanjikiza chachitsulo chimadalira kutentha ndi nthawi yopanga malo otsekemera. Momwemo, kutsekemera kuyenera kumalizidwa pafupifupi 220 ‘t 2s. M’mikhalidwe imeneyi, mayendedwe amakankhira amkuwa ndi malata atulutsa zida zolimba zazitsulo Cu3Sn ndi Cu6Sn5 ndi makulidwe pafupifupi 0.5μm. Kuphatikizana kosakwanira kumakhala kofala pamalumikizidwe ozizira kapena osungunuka omwe sanakwezeredwe kutentha koyenera nthawi yowotcherera ndipo kumatha kubweretsa kudulidwa kwa PCB weld. Mosiyana ndi izi, zigawo zazitsulo zazitsulo zolimba kwambiri, zomwe zimakonda kutenthedwa kapena kutenthetsedwa kwa nthawi yayitali, zimabweretsa mphamvu zolimba za ma PCB.