1 Mawu Oyamba
Pamsonkhano wa komiti yadera, phala la solder limasindikizidwa pa board board solder pad, ndiyeno zida zosiyanasiyana zamagetsi zimayikidwa. Pomaliza, pambuyo ng'anjo reflow, mikanda malata mu solder phala amasungunuka ndi mitundu yonse ya zigawo zikuluzikulu zamagetsi ndi solder pad wa bolodi dera ndi welded palimodzi kuzindikira msonkhano wa submodules magetsi. surfacemounttechnology (sMT) ikugwiritsidwa ntchito mochulukira muzinthu zonyamula zolemera kwambiri, monga phukusi ladongosolo (siP), zida za ballgridarray (BGA), ndi zida zopanda mphamvu, phukusi la square flat pin-less package (quad aatNo-lead, lotchedwa QFN ) chipangizo.
Chifukwa cha makhalidwe a solder phala kuwotcherera ndondomeko ndi zipangizo, pambuyo kuwotcherera reflow wa zipangizo zazikulu solder pamwamba, padzakhala mabowo m'dera solder kuwotcherera, zomwe zidzakhudza katundu magetsi, katundu matenthedwe ndi katundu mawotchi a mankhwala Magwiridwe, ndi ngakhale kuchititsa kulephera mankhwala Choncho, kusintha solder phala reflow kuwotcherera patsekeke wakhala ndondomeko ndi luso vuto liyenera kuthetsedwa, ofufuza ena kusanthula ndi kuphunzira zimene zimayambitsa BGA solder mpira kuwotcherera patsekeke, ndipo anapereka njira zothetsera, ochiritsira solder Pasta reflow kuwotcherera njira kuwotcherera dera la QFN lalikulu kuposa 10mm2 kapena kuwotcherera malo aakulu kuposa 6 mm2 wa bare chip yankho akusowa.
Gwiritsani ntchito kuwotcherera kwa Preformsolder ndi vacuum reflux ng'anjo kuti muwongolere dzenje. Zopangiratu solder zimafuna zida zapadera kuti ziloze kusinthasintha. Mwachitsanzo, chipcho chimasinthidwa ndikupendekeka kwambiri chip chikayikidwa mwachindunji pa solder yopangidwa kale. Ngati flux phiri Chip ndi reflow ndiyeno mfundo, ndondomeko chiwonjezeke ndi awiri reflow, ndi mtengo wa prefabricated solder ndi flux zakuthupi ndi apamwamba kuposa solder phala.
Zida za vacuum reflux ndizokwera mtengo kwambiri, mphamvu ya vacuum ya chipinda chodziyimira payokha ndiyotsika kwambiri, mtengo wake siwokwera, ndipo vuto la malata ndi lalikulu, lomwe ndilofunika kwambiri pakugwiritsa ntchito kachulukidwe kakang'ono komanso kamvekedwe kakang'ono. mankhwala. Mu pepala ili, kutengera ochiritsira solder phala reflow kuwotcherera ndondomeko, njira yatsopano yachiwiri reflow kuwotcherera akupangidwa ndi anayambitsa kusintha kuwotcherera patsekeke ndi kuthetsa mavuto a kugwirizana ndi pulasitiki chisindikizo akulimbana chifukwa cha kuwotcherera patsekeke.
2 Solder phala kusindikiza reflow kuwotcherera patsekeke ndi njira kupanga
2.1 Mphepo yowotcherera
Pambuyo kuwotcherera reflow, mankhwalawa adayesedwa pansi pa x-ray. Mabowo omwe amawotchera okhala ndi utoto wopepuka adapezeka kuti ndi chifukwa chosakwanira pazitsulo zowotcherera, monga tawonera pa Chithunzi 1.
X-ray kuzindikira dzenje kuwira
2.2 Mapangidwe limagwirira wa kuwotcherera patsekeke
Kutenga phala la solder la sAC305 monga chitsanzo, kapangidwe kake ndi ntchito zikuwonetsedwa mu Table 1. Mikanda ya flux ndi malata imagwirizanitsidwa pamodzi mu mawonekedwe a phala. Kulemera kwa tini solder to flux ndi pafupifupi 9: 1, ndi chiŵerengero cha voliyumu ndi pafupifupi 1: 1.
Pambuyo pa phala la solder lisindikizidwa ndikuyikidwa ndi zipangizo zosiyanasiyana zamagetsi, phala la solder lidzadutsa magawo anayi a preheating, activation, reflux ndi kuzizira pamene ikudutsa mu ng'anjo ya reflux. Mkhalidwe wa solder phala ndi wosiyananso ndi kutentha kosiyana mu magawo osiyanasiyana, monga momwe tawonetsera pa Chithunzi 2.
Mbiri ya gawo lililonse la reflow soldering
Mu preheating ndi activation siteji, ndi kosakhazikika zigawo zikuluzikulu mu flux mu solder phala adzakhala volatilized mu mpweya pamene kutentha. Panthawi imodzimodziyo, mpweya udzapangidwa pamene oxide pamwamba pa kuwotcherera wosanjikiza amachotsedwa. Ena mwa mipweyayi idzasungunuka ndikusiya phala la solder, ndipo mikanda yogulitsira idzatsekedwa mwamphamvu chifukwa cha kusinthasintha kwa kutentha. Mu reflux siteji, otsala flux mu solder phala adzakhala nthunzi mofulumira, mikanda malata adzasungunuka, pang'ono kusuntha kosakhazikika mpweya ndi mpweya wambiri pakati pa malata mikanda sadzamwazikana mu nthawi, ndi zotsalira mu malata osungunuka ndi pansi pa mphamvu ya malata osungunuka ndi masangweji a hamburger ndipo amagwidwa ndi bolodi la solder pad ndi zipangizo zamagetsi, ndipo mpweya wokutidwa mu malata amadzimadzi ndizovuta kuthawa kokha ndi kuwonjezereka kwapamwamba. mwachidule. Chitini chosungunukacho chikazizira ndikukhala malata olimba, timabowo timatulutsa timabowo tating'ono ting'onoting'ono ndipo timabowo timapanga, monga momwe chithunzi 3 chikusonyezera.
Chithunzi chojambula cha void chopangidwa ndi solder paste reflow welding
Choyambitsa chowotcherera pabowo ndi chakuti mpweya kapena mpweya wosasunthika wokutidwa mu solder phala pambuyo pa kusungunuka sunatulutsidwe kwathunthu. Zomwe zimakhudzidwa zimaphatikizirapo zinthu za solder phala, mawonekedwe osindikizira a solder, kuchuluka kwa kusindikiza kwa solder, kutentha kwa reflux, nthawi ya reflux, kukula kwa kuwotcherera, kapangidwe kake ndi zina zotero.
3. Chitsimikizo cha chikoka zinthu za solder phala kusindikiza reflow kuwotcherera mabowo
Mayeso a QFN ndi chip opanda kanthu adagwiritsidwa ntchito kutsimikizira zomwe zimayambitsa zowotcherera zowotcherera, komanso kupeza njira zowongolera zowotcherera zosindikizira zosindikizidwa ndi phala la solder. QFN ndi anabala Chip solder phala reflow kuwotcherera mankhwala mbiri ikuwonetsedwa Chithunzi 4, QFN kuwotcherera pamwamba kukula ndi 4.4mmx4.1mm, kuwotcherera pamwamba ndi malata malata (100% koyera malata); Kuwotcherera kwa chip chopanda kanthu ndi 3.0mmx2.3mm, chowotchereracho chimakhala ndi nickel-vanadium bimetallic layer, ndipo pamwamba pake ndi vanadium. The kuwotcherera PAD wa gawo lapansi anali electroless faifi tambala-palladium golide-kuviika, ndi makulidwe anali 0.4μm/0.06μm/0.04μm. SAC305 solder paste imagwiritsidwa ntchito, zida zosindikizira za solder paste ndi DEK Horizon APix, zida za ng'anjo ya reflux ndi BTUPyramax150N, ndipo zida za x-ray ndi DAGExD7500VR.
QFN ndi zojambula zopanda chip kuwotcherera
Kuti tithandizire kufananiza zotsatira za mayeso, kuwotchereranso kunkachitika malinga ndi zomwe zili mu Table 2.
Reflow welding condition table
Pambuyo kukwera pamwamba ndi kuwotcherera reflow anamalizidwa, ndi kuwotcherera wosanjikiza wapezeka ndi X-ray, ndipo anapeza kuti panali mabowo aakulu mu kuwotcherera wosanjikiza pansi pa QFN ndi anabala Chip, monga momwe chithunzi 5.
QFN ndi Chip Hologram (X-ray)
Popeza kukula kwa mkanda wa malata, makulidwe a zitsulo zachitsulo, kuchuluka kwa malo otsegulira, mawonekedwe a zitsulo zachitsulo, nthawi ya reflux ndi kutentha kwa ng'anjo yamoto zonse zidzakhudza zowotcherera zowotcherera, pali zinthu zambiri zomwe zimakhudza, zomwe zidzatsimikiziridwa mwachindunji ndi mayeso a DOE, ndi chiwerengero cha kuyesa. magulu adzakhala aakulu kwambiri. Ndikofunikira kuyang'ana mwachangu ndikuzindikira zinthu zazikulu zomwe zimathandizira pakuyesa kufananiza, ndikuwonjezeranso zinthu zazikulu zomwe zimalimbikitsa kudzera mu DOE.
3.1 Makulidwe a mabowo a solder ndi mikanda ya malata ya solder
Ndi type3 (kukula kwa mikanda 25-45 μm) SAC305 solder phala kuyesa, zina sizisintha. Pambuyo pakubwezeretsanso, mabowo omwe ali mu solder amayezedwa ndikufananizidwa ndi phala la type4 solder. Iwo anapeza kuti mabowo mu solder wosanjikiza si zosiyana kwambiri pakati pa mitundu iwiri ya solder phala, kusonyeza kuti solder phala ndi kukula osiyana mkanda alibe chikoka chodziwikiratu pa mabowo mu solder wosanjikiza, amene si chikoka chinthu, monga zikuwonetsedwa mu FIG. 6 Monga momwe zasonyezedwera.
Kuyerekeza mabowo achitsulo a malata okhala ndi mitundu yosiyanasiyana ya tinthu
3.2 Makulidwe a zitsulo zowotcherera komanso mauna osindikizidwa achitsulo
Pambuyo pa reflow, dera lamkati lazitsulo lopangidwa ndi welded linayesedwa ndi zitsulo zosindikizidwa zosindikizidwa ndi makulidwe a 50 μm, 100 μm ndi 125 μm, ndi zina sizinasinthe. Zinapezeka kuti zotsatira za makulidwe osiyanasiyana a zitsulo zachitsulo (solder phala) pa QFN zimafaniziridwa ndi zitsulo zosindikizidwa zachitsulo ndi makulidwe a 75 μm Pamene makulidwe a zitsulo zachitsulo akuwonjezeka, dera lazitsulo limachepa pang'onopang'ono. Akafika pa makulidwe ena (100μm), malo otsekerawo amabwerera m'mbuyo ndikuyamba kuwonjezereka ndi kuchuluka kwa makulidwe a zitsulo zachitsulo, monga momwe tawonetsera pa Chithunzi 7.
Izi zikuwonetsa kuti kuchuluka kwa phala la solder kukuchulukirachulukira, malata amadzimadzi okhala ndi reflux amaphimbidwa ndi chip, ndipo kutuluka kwa mpweya wotsalira kumakhala kocheperako mbali zinayi. Kuchuluka kwa phala la solder likasinthidwa, kutulutsa kwa mpweya wotsalira kumachulukiranso, ndipo kuphulika kwa mpweya komwe kumakulungidwa ndi malata amadzimadzi kapena mpweya wotuluka mu malata amadzimadzi kumapangitsa malata amadzimadzi kuwomba mozungulira QFN ndi chip.
Mayesowo adapeza kuti pakuwonjezeka kwa makulidwe a zitsulo zachitsulo, kuphulika kwamoto komwe kumachitika chifukwa cha kutuluka kwa mpweya kapena mpweya wotentha kumawonjezekanso, ndipo mwayi wa malata ozungulira QFN ndi chip nawonso udzawonjezeka mofanana.
Kuyerekeza mabowo mu zitsulo mauna osiyanasiyana makulidwe
3.3 Chiŵerengero cha dera la kuwotcherera pabowo ndi kutsegula kwa zitsulo zachitsulo
Ma mesh achitsulo osindikizidwa omwe ali ndi mlingo wotsegulira 100%, 90% ndi 80% adayesedwa, ndipo zinthu zina sizinasinthe. Pambuyo pa reflow, dera lamkati lazitsulo zowotcherera linkayezedwa ndikufaniziridwa ndi mauna achitsulo osindikizidwa ndi 100% kutsegula. Zinapezeka kuti panalibe kusiyana kwambiri pabowo la welded wosanjikiza pansi pa zikhalidwe za mlingo wotsegulira wa 100% ndi 90% 80%, monga momwe tawonetsera pa Chithunzi 8.
Kuyerekeza kwa cavity kwa malo osiyanasiyana otsegulira a ma mesh achitsulo osiyanasiyana
3.4 Zowotcherera pabowo ndi kusindikizidwa zitsulo mauna mawonekedwe
Ndi mayeso osindikizira a mawonekedwe a solder phala la Mzere b ndi gululi wokhotakhota c, zinthu zina sizisintha. Pambuyo pa reflow, malo apakati pazitsulo zowotcherera amayezedwa ndikufanizidwa ndi mawonekedwe osindikizira a grid a. Zikuoneka kuti palibe kusiyana kwakukulu pabowo la kuwotcherera wosanjikiza pansi pa gridi, mizere ndi gridi yotsatiridwa, monga momwe tawonetsera pa Chithunzi 9.
Kuyerekeza mabowo munjira zosiyanasiyana zotsegulira za mauna achitsulo
3.5 Kuwotcherera pabowo ndi nthawi ya reflux
Pambuyo pa nthawi yayitali ya reflux (70 s, 80 s, 90 s), zinthu zina sizisintha, dzenje lazitsulo zowotcherera linayesedwa pambuyo pa reflux, ndipo poyerekeza ndi nthawi ya reflux ya 60s, zinapezeka kuti ndi kuwonjezeka kwa nthawi ya reflux, malo otsekemera amatha kuchepa, koma kuchepetsa matalikidwe pang'onopang'ono kunachepa pang'onopang'ono ndi kuwonjezeka kwa nthawi, monga momwe tawonetsera pa Chithunzi 10. Izi zikuwonetsa kuti pakakhala nthawi yosakwanira ya reflux, kuonjezera nthawi ya reflux kumapangitsa kuti mpweya uwonongeke. atakulungidwa mu malata osungunuka amadzimadzi, koma pambuyo pa nthawi ya reflux imawonjezeka kufika pa nthawi inayake, mpweya wokutidwa ndi malata amadzimadzi ndizovuta kusefukiranso. Nthawi ya Reflux ndi chimodzi mwazinthu zomwe zimakhudza minyewa yowotcherera.
Kuyerekeza kosawerengeka kwa kutalika kwa nthawi ya reflux
3.6 Kuwotchera pabowo ndi kutentha kwambiri kwa ng'anjo
Ndi 240 ℃ ndi 250 ℃ nsonga kutentha ng'anjo mayeso ndi zina zosasinthika, patsekeke dera la welded wosanjikiza anayesedwa pambuyo reflow, ndipo poyerekeza ndi 260 ℃ pachimake ng'anjo kutentha, anapeza kuti pansi pa nsonga zosiyanasiyana kutentha ng'anjo kutentha, patsekeke wosanjikiza welded wa QFN ndi chip sichinasinthe kwambiri, monga momwe chithunzi 11. Zimasonyeza kuti osiyana pachimake ng'anjo kutentha alibe zotsatira zoonekeratu pa QFN ndi dzenje mu kuwotcherera wosanjikiza Chip, amene si chinthu chochititsa.
Kuyerekeza kwachabechabe kwa kutentha kwapamwamba kosiyanasiyana
Mayesero omwe ali pamwambawa akuwonetsa kuti zinthu zazikulu zomwe zikukhudza weld layer ya QFN ndi chip ndi nthawi ya reflux komanso makulidwe achitsulo.
4 Solder phala kusindikiza reflow kuwotcherera patsekeke kusintha
Mayeso a 4.1DOE kuti apititse patsogolo kuwotcherera
Bowo la kuwotcherera wosanjikiza wa QFN ndi chip adawongoleredwa ndikupeza mtengo wokwanira wazinthu zazikulu zomwe zimakopa (nthawi ya reflux ndi makulidwe achitsulo). Phala la solder linali SAC305 type4, mawonekedwe achitsulo a mesh anali mtundu wa gridi (100% kutsegulira digiri), kutentha kwa ng'anjo yapamwamba kunali 260 ℃, ndi zina zoyesera zinali zofanana ndi zida zoyesera. Mayeso a DOE ndi zotsatira adawonetsedwa mu Table 3. Zomwe zimakhudzidwa ndi makulidwe azitsulo zachitsulo ndi nthawi ya reflux pa QFN ndi mabowo owotcherera a chip akuwonetsedwa mu Chithunzi 12. Kupyolera mu kusanthula kwa kuyanjana kwa zinthu zazikulu zomwe zimakhudza kwambiri, Zimapezeka kuti kugwiritsa ntchito 100 μm zitsulo zachitsulo makulidwe. ndi 80s reflux nthawi akhoza kwambiri kuchepetsa kuwotcherera patsekeke QFN ndi chip. The kuwotcherera patsekeke mlingo wa QFN wachepetsedwa kuchokera pa pazipita 27.8% mpaka 16.1%, ndi kuwotcherera pabowo mlingo wa chip wachepa kuchokera pazipita 20.5% mpaka 14.5%.
M'mayeso, zinthu 1000 zidapangidwa pansi pamikhalidwe yabwino kwambiri (100 μm chitsulo makulidwe, 80 s reflux nthawi), ndipo kuchuluka kwa kuwotcherera kwa 100 QFN ndi chip zidayezedwa mwachisawawa. Mlingo wapakatikati wowotcherera wa QFN unali 16.4%, ndipo pafupifupi chipwirikiti chowotcherera cha chip chinali 14.7% Mlingo wa weld wa chip ndi chip mwachiwonekere wachepetsedwa.
4.2 Njira yatsopanoyi imapangitsa kuti nsonga zowotcherera
zenizeni kupanga zinthu ndi mayeso zimasonyeza kuti pamene kuwotcherera patsekeke m'dera pansi pa Chip ndi zosakwana 10%, Chip patsekeke udindo akulimbana vuto sizidzachitika pa kutsogolera kugwirizana ndi akamaumba. The ndondomeko magawo wokometsedwa ndi DOE sangathe kukwaniritsa zofunika kusanthula ndi kuthetsa mabowo mu ochiritsira solder phala reflow kuwotcherera, ndi kuwotcherera patsekeke m'dera mlingo wa chip ayenera kuchepetsedwa zina.
Popeza chip chophimbidwa pa solder chimalepheretsa gasi mu solder kuti asathawe, mlingo wa dzenje pansi pa chip umachepetsedwa kwambiri pochotsa kapena kuchepetsa mpweya wotsekedwa ndi solder. Njira yatsopano yowotcherera ndi kusindikiza kwa solder phala imatengedwa: kusindikiza phala la solder, kutulutsanso kumodzi kosaphimba QFN ndi chip chopanda kutulutsa mpweya mu solder; Njira yeniyeni yosindikizira yachiwiri ya solder paste, chigamba ndi reflux yachiwiri ikuwonetsedwa pa Chithunzi 13.
Pamene 75μm wandiweyani solder phala kusindikizidwa kwa nthawi yoyamba, ambiri mpweya mu solder popanda Chip chivundikirocho amatuluka pamwamba, ndi makulidwe pambuyo reflux pafupifupi 50μm. Akamaliza reflux chachikulu, mabwalo ang'onoang'ono amasindikizidwa padziko utakhazikika solidified solder (kuti kuchepetsa kuchuluka kwa solder phala, kuchepetsa kuchuluka kwa mpweya spillover, kuchepetsa kapena kuthetsa solder spatter), ndi solder phala ndi makulidwe a 50 μm (zotsatira zoyesedwa pamwambapa zikuwonetsa kuti 100 μm ndi yabwino kwambiri, kotero makulidwe a kusindikiza kwachiwiri ndi 100 μm.50 μm = 50 μm), kenaka yikani chip, kenako bwererani kupyola 80 s. Pafupifupi palibe bowo mu solder pambuyo pa kusindikiza koyamba ndi kubwereza, ndipo phala la solder mu kusindikiza kwachiwiri ndi laling'ono, ndipo dzenje lowotcherera ndiloling'ono, monga momwe tawonetsera pa Chithunzi 14.
Pambuyo printings awiri a solder phala, dzenje kujambula
4.3 Kutsimikizira kwa kuwotcherera patsekeke zotsatira
Kupanga zinthu 2000 (kukhuthala kwa woyamba kusindikiza zitsulo mauna 75 μm, makulidwe achiwiri kusindikiza zitsulo mauna 50 μm), zinthu zina sizinasinthe, mwachisawawa muyeso wa 500 QFN ndi Chip kuwotcherera patsekeke mlingo, anapeza kuti ndondomeko yatsopano. pambuyo reflux woyamba palibe patsekeke, pambuyo yachiwiri reflux QFN Pazipita kuwotcherera patsekeke mlingo ndi 4.8%, ndi pazipita kuwotcherera patsekeke mlingo wa Chip ndi 4.1%. Poyerekeza ndi njira yoyamba yosindikizira yosindikizira yosindikizira imodzi ndi ndondomeko yowonjezereka ya DOE, zitsulo zowotcherera zimachepetsedwa kwambiri, monga momwe tawonetsera pa Chithunzi 15. Palibe ming'alu ya chip yomwe inapezeka pambuyo pa mayesero ogwira ntchito azinthu zonse.
5 Mwachidule
The kukhathamiritsa kwa solder phala kusindikiza kuchuluka ndi reflux nthawi akhoza kuchepetsa kuwotcherera patsekeke dera, koma kuwotcherera patsekeke mlingo akadali lalikulu. Kugwiritsa ntchito njira ziwiri zowotcherera phala zosindikizira zosindikizira zimatha bwino ndikukulitsa kuchuluka kwa kuwotcherera. Malo owotcherera a QFN dera bare chip akhoza kukhala 4.4mm x4.1mm ndi 3.0mm x2.3mm motsatana popanga misa Mlingo wa kuwotcherera kwa reflow umayang'aniridwa pansi pa 5%, zomwe zimathandizira kudalirika komanso kudalirika kwa kuwotchereranso. Kafukufuku mu pepalali akupereka chidziwitso chofunikira pakuwongolera vuto la kuwotcherera kwa malo akulu.
Nthawi yotumiza: Jul-05-2023
