1 Nhanganyaya
Mugungano redunhu redunhu, solder paste inodhindwa padhipatimendi redunhu solder pad, uye ipapo zvakasiyana-siyana zvemagetsi zvinonamirwa. Chekupedzisira, mushure mechoto chekuyerera, marata ari mu solder paste anonyungudutswa uye marudzi ese ezvigadzirwa zvemagetsi uye solder pad yedare redunhu zvinosungirirwa pamwechete kuti zvione kuungana kwemagetsi submodules. surfacemounttechnology (sMT) iri kuwedzera kushandiswa muzvigadzirwa zvekurongedza zvakanyanya, senge system level package (siP), ballgridarray (BGA) zvishandiso, uye isina simba Chip, square flat pin-less package (quad aatNo-lead, inonzi QFN ) mudziyo.
Nekuda kwehunhu hwe solder paste welding process uye zvekushandisa, mushure me reflow welding yeaya mahombe solder pamusoro pezvishandiso, pachava nemakomba munzvimbo ye solder welding, izvo zvinokanganisa midziyo yemagetsi, zvivakwa zvinopisa uye michina yechigadzirwa Performance, uye kunyange kutungamirira chigadzirwa kukundikana, saka, kuvandudza solder namatidza reflow welding mhango yava muitiro uye unyanzvi dambudziko rinofanira kugadziriswa, vamwe vatsvakurudzi vakaongorora uye kudzidza zvikonzero BGA solder bhora nomoto mhango, uye akapa kuvandudza mhinduro, kwakajairika solder. paste reflow welding process welding nzvimbo yeQFN yakakura kupfuura 10mm2 kana welding nzvimbo yakakura kupfuura 6 mm2's bare chip solution iri kushomeka.
Shandisa Preformsolder welding uye vacuum reflux furnace welding kuvandudza gomba re weld. Prefabricated solder inoda midziyo yakakosha kunongedza flux. Semuenzaniso, iyo chip inogadziriswa uye yakarereka zvakakomba mushure mekunge chip yaiswa zvakananga pane yakafanogadzirirwa solder. Kana iyo flux mount chip ichiyerera uye yobva yanongedza, maitiro anowedzerwa neaviri reflow, uye mutengo weyakagadzirwa solder uye flux zvinhu wakakwira zvakanyanya kupfuura solder paste.
Vacuum reflux midziyo inodhura zvakanyanya, iyo vacuum yekamuri yakazvimiririra yakadzikira, mutengo wekuita hauna kukwirira, uye dambudziko rekupwanya kwerata rakakomba, chinova chinhu chakakosha mukushandiswa kwehupamhi-density uye diki-pitch. zvigadzirwa. Mupepa iri, zvichibva pane yakajairwa solder paste reflow welding process, itsva yechipiri reflow welding process inogadzirwa uye inounzwa kuti ivandudze iyo welding mhango uye kugadzirisa matambudziko ekubatanidza uye kuputika kwepurasitiki chisimbiso chinokonzerwa newelding cavity.
2 Solder paste kudhinda reflow welding cavity uye kugadzira michina
2.1 Welding cavity
Mushure mekudzorerazve welding, chigadzirwa chakaedzwa pasi pe x-ray. Maburi ari munzvimbo yewelding ane ruvara rwakareruka akawanikwa ari nekuda kwekusakwana solder muwelding layer, sezvakaratidzwa muFigure 1.
X-ray kuonekwa kwegomba rebubble
2.2 Magadzirirwo ekugadzirisa mhango ye welding
Kutora sAC305 solder paste semuenzaniso, kuumbwa kukuru uye basa rinoratidzwa muTebhu 1. Iyo flux uye tin beads zvakabatanidzwa pamwe chete mu paste shape. Huremu hwehuremu hwetini solder kusvika pa9: 1, uye huwandu hwehuwandu hunenge 1: 1.
Mushure mokunge solder paste yakadhindwa uye yakasungirirwa nemhando dzakasiyana-siyana dzemagetsi, iyo solder paste ichaita nhanho ina dzepreheating, activation, reflux uye kutonhora kana ichipfuura nepakati reflux choto. Mamiriro eiyo solder paste zvakare akasiyana nekudziya kwakasiyana mumatanho akasiyana, sezvakaratidzwa mumufananidzo 2.
Profile referensi yenzvimbo yega yega ye reflow soldering
Mune preheating uye activation nhanho, iyo inovhuvhuta zvikamu mu flux mune solder paste ichave yakanyanyiswa kuita gasi kana yapiswa. Panguva imwecheteyo, magasi anozogadzirwa kana oxide iri pamusoro peiyo welding layer inobviswa. Mamwe emagasi aya anozonyungudika uye osiya solder paste, uye mabheji anotengeswa anozonyatso kusungirirwa nekuda kwekushata kwekuyerera. Mune reflux nhanho, iyo yakasara flux mu solder paste inoputika nekukurumidza, marata mabheji achanyunguduka, kashoma kekuyerera gasi rinoputika uye yakawanda yemhepo pakati pematani mabheji haizoparadzirwe nenguva, uye zvakasara mumhepo. tin yakanyungudutswa uye pasi pekukakavara kwetani yakanyungudutswa kune hamburger sandwich chimiro uye inobatwa nedhiketi redhisheni solder pad uye zvigadzirwa zvemagetsi, uye gasi rakaputirwa mugasi remvura rakaoma kupukunyuka chete nekukwira kumusoro. pfupi. Kana tini rakanyungudutswa ratonhora pasi roita simbi yakasimba, pores anoonekwa muwelding layer uye maburi anogadzirwa anogadzirwa, sezvakaratidzwa muFigure 3.
Schematic dhayagiramu ye void yakagadzirwa ne solder paste reflow welding
Mhedzisiro yewelding cavity ndeyekuti mhepo kana gasi rinoputika rakaputirwa mune solder paste mushure mekunyunguduka harina kubviswa zvachose. Zvinhu zvinofurira zvinosanganisira solder paste zvinhu, solder paste kudhinda chimiro, solder paste kudhinda huwandu, reflux tembiricha, reflux nguva, welding size, chimiro uye zvichingodaro.
3. Verification yekufurira zvinhu zve solder paste kudhinda reflow welding maburi
QFN uye bare chip bvunzo dzakashandiswa kusimbisa zvikonzero zvikuru zve reflow welding voids, uye kutsvaga nzira dzekuvandudza reflow welding voids yakadhindwa nesolder paste. QFN uye bare chip solder paste reflow welding product profile inoratidzwa muFigure 4,QFN welding surface size is 4.4mmx4.1mm, welding surface is tinned layer (100% pure tin); Saizi yewelding ye bare chip ndeye 3.0mmx2.3mm, iyo welding layer yakapushwa nickel-vanadium bimetallic layer, uye iyo yepamusoro layer ivanadium. Iyo welding pad ye substrate yaive electroless nickel-palladium goridhe-kunyura, uye ukobvu hwaive 0.4μm/0.06μm/0.04μm. SAC305 solder paste inoshandiswa, solder paste printing equipment is DEK Horizon APix, reflux furnace equipment ndeye BTUPyramax150N, uye x-ray midziyo iDAGExD7500VR.
QFN uye isina chip welding mifananidzo
Kufambisa kuenzanisa kwemhedzisiro yebvunzo, reflow welding yakaitwa pasi pemamiriro ari muTafura 2.
Reflow welding mamiriro tafura
Mushure mekuiswa kwepamusoro uye reflow welding kwapera, iyo welding layer yakaonekwa neX-ray, uye zvakaonekwa kuti pane makomba mahombe muwelding layer pazasi peQFN uye isina chip, sezvakaratidzwa mumufananidzo 5.
QFN uye Chip Hologram (X-ray)
Sezvo tin bead size, simbi mesh ukobvu, kuvhura nzvimbo chiyero, simbi mesh chimiro, reflux nguva uye peak tembiricha yevira zvese zvinokanganisa reflow welding voids, pane zvakawanda zvinofurira zvinhu, izvo zvinozosimbiswa zvakananga neDOE bvunzo, uye huwandu hwekuyedza. mapoka achava akakurisa. Izvo zvinodikanwa kukurumidza kuongorora uye kuona izvo zvikuru zvinopesvedzera zvinhu kuburikidza nekuenzanisa bvunzo bvunzo, uye wobva wawedzera optimize hukuru hwekufurira zvinhu kuburikidza neDOE.
3.1 Zviyero zvemaburi emasolder uye solder namira tin bead
Ne type3 (bead size 25-45 μm)SAC305 solder paste bvunzo, mamwe mamiriro anoramba asina kuchinjika. Mushure mekuyerera zvakare, maburi ari mushizha anoyerwa uye anoenzaniswa netype4 solder paste. Zvinoonekwa kuti maburi ari mushizha haana kusiyana zvakanyanya pakati pemhando mbiri dze solder paste, zvichiratidza kuti solder paste ine saizi yebead yakasiyana haina pesvedzero iri pachena pamaburi ari mushizha, iyo isiri inofurira chinhu, sezvinoratidzwa muFIG. 6 Sezvakaratidzwa.
Kuenzanisa kwesimbi yesimbi poda maburi ane akasiyana particle saizi
3.2 Hukobvu hwewelding mhango uye yakadhindwa mesh yesimbi
Mushure mekudzokazve, nzvimbo yegomba yewelded layer yakayerwa nesimbi yakadhindwa mesh nehupamhi hwe50 μm, 100 μm uye 125 μm, uye mamwe mamiriro akaramba asina kuchinjwa. Zvakaonekwa kuti mhedzisiro yehukobvu hwakasiyana hwesimbi mesh (solder paste) paQFN yakafananidzwa neyeiyo yakadhindwa mesh yesimbi nehupamhi hwe75 μm Sezvo ukobvu hwesimbi mesh hunowedzera, nzvimbo yemhango inoderera zvishoma nezvishoma. Mushure mekusvika kune imwe gobvu (100μm), iyo nzvimbo yegomba ichadzokera kumashure uye inotanga kuwedzera nekuwedzera kwehupamhi hwesimbi mesh, sezvakaratidzwa mumufananidzo 7.
Izvi zvinoratidza kuti kana huwandu hwe solder paste huchiwedzerwa, iyo tini yemvura ine reflux yakafukidzwa nechip, uye kubuda kwemhepo yakasara kupukunyuka kunongotetepa pamativi mana. Kana huwandu hwesolder paste hwashandurwa, kubuda kwemhepo yakasara kupukunyuka kunowedzerawo, uye kuputika kwemhepo kwakaputirwa mumarata emvura kana gasi rinoputika riri kubuda mugasi remvura kuchaita kuti tini remvura riparare kutenderera QFN uye chip.
Muedzo wakaona kuti nekuwedzera kwekukora kwesimbi mesh, kuputika kwebubble kunokonzerwa nekupukunyuka kwemhepo kana gasi rinoputika richawedzerawo, uye mukana wekupfapfaidza kwerata kutenderera QFN uye chip ichawedzerawo zvinoenderana.
Kuenzanisa kwemakomba musimbi mesh yehupamhi hwakasiyana
3.3 Nharaunda chiyero chewelding cavity uye simbi mesh kuvhurwa
Iyo yakadhindwa mesh yesimbi ine mukana wekuvhura we100%, 90% uye 80% yakaedzwa, uye mamwe mamiriro akaramba asina kuchinjwa. Mushure mekufefetera, nzvimbo yemhango yewalded layer yakayerwa ichienzaniswa neyakadhindwa mesh yesimbi ine 100% yekuvhura rate. Zvakaonekwa kuti pakanga pasina mutsauko wakakosha mugomba reiyo welded layer pasi pemamiriro ekuvhura kwe100% uye 90% 80%, sezvakaratidzwa mumufananidzo 8.
Cavity kuenzanisa yenzvimbo dzakasiyana dzekuvhura dzakasiyana simbi mesh
3.4 Welded mhango uye yakadhindwa simbi mesh chimiro
Nekudhinda chimiro bvunzo ye solder paste ye strip b uye inclined grid c, mamwe mamiriro anoramba asina kuchinjika. Mushure mekuyerera, nzvimbo yegomba yewelding layer inoyerwa nekuenzaniswa neinodhinda chimiro chegridi a. Inowanikwa kuti hapana mutsauko wakakosha mugomba rewelding layer pasi pemamiriro egridi, mitsetse uye yakarerekera grid, sezvakaratidzwa mumufananidzo 9.
Kuenzanisa kwemakomba mune dzakasiyana nzira dzekuvhura dzesimbi mesh
3.5 Welding cavity uye reflux nguva
Mushure menguva yakareba yereflux nguva (70 s, 80 s, 90 s) bvunzo, mamwe mamiriro anoramba asina kuchinjika, gomba muwelding layer yakayerwa mushure me reflux, uye kana ichienzaniswa nenguva yereflux ye60s, zvakaonekwa kuti nekuwedzera kwe reflux nguva, iyo welding hole nzvimbo yakaderera, asi kuderedza amplitude yakaderera zvishoma nezvishoma nekuwedzera kwenguva, sezvinoratidzwa muMufananidzo 10. Izvi zvinoratidza kuti kana nguva isina kukwana reflux nguva, kuwedzera nguva yereflux inobatsira pakuzara kwemhepo. yakaputirwa mugaba remvura yakanyungudutswa, asi mushure mekunge nguva yereflux yawedzera kusvika pane imwe nguva, mhepo yakaputirwa mumarata emvura yakaoma kupfachukira zvakare. Reflux nguva ndechimwe chezvinhu zvinokanganisa welding cavity.
Kuenzanisa kusingaenzaniswi kwehurefu hwakasiyana hwenguva reflux
3.6 Welding mhango uye peak tembiricha yevira
Iine 240 ℃ uye 250 ℃ peak tembiricha tembiricha uye mamwe mamiriro asina kuchinjika, nzvimbo yegomba yeyakaiswa welded yakayerwa mushure mekuyerera, uye kana ichienzaniswa ne260 ℃ peak tembiricha yevira, zvakaonekwa kuti pasi peakasiyana peak tembiricha yechoto mamiriro, gomba re iyo welded layer yeQFN uye chip haina kushanduka zvakanyanya, sezvakaratidzwa muFigure 11. Zvinoratidza kuti tembiricha yekupisa yechoto yakasiyana-siyana haina mhedzisiro yakajeka paQFN uye gomba mune welding layer yechip, iyo isiri iyo inofurira.
Kuenzanisa kusina maturo kwekupisa kwepamusoro kwakasiyana
Iwo maedzo ari pamusoro anoratidza kuti zvakakosha zvinokanganisa weld layer cavity yeQFN uye chip inguva reflux uye simbi mesh ukobvu.
4 Solder paste kudhinda reflow welding cavity kunatsiridza
4.1DOE bvunzo yekuvandudza welding cavity
Gomba muwelding layer yeQFN uye chip yakagadziridzwa nekuwana iyo yakakwana kukosha kweiyo huru inofurira zvinhu (reflux nguva uye simbi mesh ukobvu). Solder paste yaive SAC305 type4, simbi mesh shape yaive grid type (100% yekuvhura degree), tembiricha yechoto yepamusoro yaive 260 ℃, uye mamwe mamiriro ebvunzo aive akafanana neaya emidziyo yekuyedza. DOE bvunzo nemhedzisiro zvakaratidzwa muTebhurari 3. Izvo zvinokonzeresa zvesimbi mesh ukobvu uye reflux nguva paQFN uye chip welding maburi anoratidzwa muMufananidzo 12. Kuburikidza nekuongororwa kwekudyidzana kwezvinhu zvikuru zvinopesvedzera, Zvinoonekwa kuti kushandisa 100 μm simbi mesh ukobvu. uye 80 s reflux nguva inogona kuderedza zvakanyanya iyo welding cavity yeQFN uye chip. Welding cavity rate yeQFN yakaderedzwa kubva pahupamhi hwe27.8% kusvika 16.1%, uye welding cavity rate yechip inoderedzwa kubva pakakwirira 20.5% kusvika 14.5%.
Muyedzo, zvigadzirwa zana zvakagadzirwa pasi pemamiriro akakwana (100 μm simbi mesh ukobvu, 80 s reflux nguva), uye welding cavity rate ye100 QFN uye chip yakayerwa zvisina tsarukano. Avhareji welding cavity rate yeQFN yaive 16.4%, uye avhareji welding cavity rate ye chip yaive 14.7% Iyo weld cavity rate yechip uye chip zviri pachena kuti yakaderedzwa.
4.2 Iyo nzira nyowani inovandudza welding cavity
Iyo chaiyo yekugadzira mamiriro uye bvunzo inoratidza kuti kana welding mhango nzvimbo iri pazasi pe chip iri pasi pe10%, iyo chip cavity chinzvimbo chinoputika dambudziko hachizoitika panguva yekutungamirira bonding uye kuumbwa. Iyo maitiro maparamendi akagadziridzwa neDOE haagone kusangana nezvinodiwa zvekuongorora nekugadzirisa maburi mune yakajairwa solder paste reflow welding, uye welding cavity nzvimbo chiyero chechip chinoda kuderedzwa.
Sezvo chip yakavharwa pane solder ichidzivirira gasi mune solder kutiza, chiyero chegomba pazasi pechiputi chinowedzerwa nekubvisa kana kuderedza solder yakavharwa gasi. Nzira itsva ye reflow welding ine maviri solder paste printing inogamuchirwa: imwe solder paste kudhinda, imwe reflow isingafukidze QFN uye isina chip ichibudisa gasi mune solder; Iyo chaiyo maitiro echipiri solder paste kudhinda, chigamba uye yechipiri reflux inoratidzwa muMufananidzo 13.
Kana iyo 75μm yakakora solder paste inodhindwa kekutanga, yakawanda yegasi musolder isina chip cover inobuda kubva pamusoro, uye ukobvu mushure mereflux inenge 50μm. Mushure mekupedzwa kweiyo yekutanga reflux, madiki masikweya anodhindwa pamusoro peiyo yakatonhodzwa yakaomeswa solder (kuitira kudzikisa huwandu hwesolder paste, kuderedza huwandu hwegasi spillover, kuderedza kana kubvisa solder spatter), uye solder paste ne. kukora kwe50 μm (iyo iri pamusoro pebvunzo mhinduro inoratidza kuti 100 μm ndiyo yakanyanya kunaka, saka ukobvu hwekudhindwa kwechipiri ndeye 100 μm.50 μm = 50 μm), wozoisa chip, wozodzoka kuburikidza ne80 s. Inenge isina gomba mu solder mushure mekutanga kudhindwa uye kuyerera, uye solder paste mukudhinda kwechipiri idiki, uye gomba rewelding idiki, sezvakaratidzwa muFigure 14.
Mushure mekudhinda kuviri kwe solder paste, hollow kudhirowa
4.3 Kuongororwa kweiyo welding cavity maitiro
Kugadzirwa kwe2000 zvigadzirwa (ukobvu hwekutanga kudhinda simbi mesh 75 μm, ukobvu hwechipiri kudhinda simbi mesh i50 μm), mamwe mamiriro asina kuchinjika, chiyero chekuyeresa che500 QFN uye chip welding cavity rate, yakawana kuti maitiro matsva. mushure mekutanga reflux hapana mhango, mushure mechipiri reflux QFN Iyo yakanyanya welding cavity rate ndeye 4.8%, uye iyo yakanyanya welding cavity rate ye chip ndeye 4.1%. Kuenzaniswa neyokutanga-single-paste printing welding process uye DOE optimized process, iyo welding cavity yakaderedzwa zvakanyanya, sezvakaratidzwa muMufananidzo 15. Hapana chip cracks chakawanikwa mushure mekuedzwa kwekushanda kwezvinhu zvose.
5 Pfupiso
Iko optimization ye solder paste kudhinda huwandu uye reflux nguva inogona kuderedza welding cavity nzvimbo, asi welding cavity rate ichiri yakakura. Kushandisa maviri solder paste kudhinda reflow welding matekiniki anogona zvinobudirira uye kuwedzera welding cavity rate. Iyo welding nzvimbo yeQFN circuit bare chip inogona kuita 4.4mm x4.1mm uye 3.0mm x2.3mm zvakateerana mukugadzirwa kwakawanda Iyo cavity rate ye reflow welding inodzorwa pazasi 5%, iyo inovandudza kunaka uye kuvimbika kwereflow welding. Tsvagiridzo iri mubepa rino inopa chirevo chakakosha chekuvandudza dambudziko rewelding cavity yenzvimbo hombe welding nzvimbo.
Nguva yekutumira: Jul-05-2023
