BGA Rework: Nyanzvi Inotungamira kuPCB Chikamu Kugadziriswa

ziviso

Chii chinonzi BGA Zvikamu?

Mapakeji eBall Grid Array (BGA) anomiririra imwe yetekinoroji yepamusoro-soro yekuisa pamusoro pemagetsi emazuva ano. Kusiyana nemapakeji ekare ane lead, maBGA anoshandisa mabhora akasiyana-siyana e solder pasi pechikamu kuti agadzire kubatana kwemagetsi nemechanical nePCB. Dhizaini iyi inoita kuti pave nehuwandu hwakawanda hwemapini, kushanda zvakanaka kwekupisa, uye saizi shoma dzepakeji—zvichiita kuti maBGA ave akakosha kuma processor, memory chips, uye maIC akaomarara mumafoni, maseva, uye masisitimu emotokari.

Nei BGA Rework Matters Inokosha

Kugadziriswazve kweBGA kwakakosha mukugadzirwa nekugadzirisa maPCB nekuti zvikamu zveBGA zvisina kunaka kana kuti zvakakundikana hazvingogone kusungirirwa nemaoko sezvikamu zvine maburi. Majoini esolder akavanzika ari pasi pepakeji anoda hunyanzvi hwekubvisa, kugadzirira nzvimbo, uye kutsiva.

Mamiriro ezvinhu akajairika anoda BGA rework anosanganisira kukanganisa kugadzira (mabhiriji, voids, majoini anotonhora), kutadza kwemumunda kubva pakupisa bhasikoro kana kushushikana kwemagetsi, uye mainjiniya ekuchinja mirairo inoda kuvandudzwa kwechikamu.

Zvishandiso uye Zvishandiso zveBGA Rework

Rework Stations

Professional BGA rework inoda zviteshi zvakatsaurirwa zvine chaiwo ekudziya masisitimu.

• Hot air rework stations -Yakatarisana ne convective kupisa kuburikidza ne programmable nozzles inoderedza kupisa kushushikana pazvinhu zvakatenderedza.
• Infrared (IR) rework masisitimu -Uniform kupisa munzvimbo dzakakura kunoderedza oxidation uye inova nechokwadi chekugovera tembiricha.

Hybrid masisitimu anosanganisa ese ari maviri matekinoroji anopa yakanyanya kuchinjika, zvichiita kuti vashandisi vasarudze yakanakisa yekudziya nzira zvichienderana nechikamu chechikamu uye kuvaka bhodhi.

Soldering uye Flux Zvishandiso

Pamusoro pemidziyo yekudziya yekutanga, BGA rework inoda maturusi ekubatsira:

• zvakarurama Kutengesa simbi kubasa rekubata-bata
• Vacuum pickup zvishandiso pakubata chikamu
• Flux applicators (mapeni, majekiseni, kana masisitimu ekuparadzira)
• Solder paste stencils kana preforms kuitira reballing mashandiro

Yakakwirira-yemhando isina-yakachena kana mvura-inonyungudika flux inokodzera solder alloy (inotungamira kana isina-inotungamira) inovimbisa kunyorova kwakakodzera uye inoderedza post-rework yekuchenesa zvinodiwa.

Inspection Equipment

Yakakwana yekuongorora kugona haina-kutaurirana kune BGA rework kusimbiswa.

• Stereo maikorosikopu gonesa kuongororwa kwekuona kwe solder paste deposition uye kurongeka.
• X-ray yekuongorora maitiro ratidza zvakavanzwa kuremara pasi peBGA-voids, bridging, head-in-pillow, uye kusakwana solder volume.
• Automated optical inspection (AOI) inopa kukurumidza kuongororwa kwechokwadi chekuisa.

Pasina maturusi ekuongorora akakodzera, BGA rework budiriro haigone kuvimbiswa nekuvimbika.

BGA Rework Maitiro Nhanho-ne-Nhanho

Kugadzirira

Kunyatsogadzirira kunogadzirisa mhedzisiro yebasa. Tanga nekuchenesa PCB kubvisa zvinosvibisa zvinogona kukanganisa kupisa kana kuongorora. Ita ongororo iri kuuya yekunyora mamiriro aripo uye kuona chakakanganisika chinoda kugadziriswa. Isa tepi yekupisa yepamusoro-yekushisa kana aluminium inodzivirira kuchengetedza zvikamu zviri pedyo-kunyanya izvo zvine mwero wakadzika wekuyerera tembiricha kana hunyoro hwekunzwa. Simbisa chinongedzo chechikamu uye simbisa pad-to-bhora kunyoresa zvinodiwa.

Kubviswa kweBGA Yakaremara

Kubviswa kwechikamu kunotevera kudzorwa kwekupisa. Preheat iyo PCB yese kubva pazasi kuti uderedze kupisa kwemagetsi uye kudzivirira warpage-kazhinji kusvika 150-180 ° C zvichienderana nekukora kwebhodhi. Isa kupisa-parutivi kupisa uchishandisa mhepo inopisa kana IR system, uchitevera chimiro chinotaridza chepakutanga reflow curve. Kana solder yasvika liquidus, shandisa vacuum pickup kusimudza BGA vertically. Usambotsvedza kana kumonya chikamu, sezvo izvi zvinogona kubvarura mapadhi kubva kune substrate.

Board Cleaning

Mushure mekubviswa kwechikamu, yakasara solder inofanira kucheneswa kubva pamapedhi. Shandisa copper braid (solder wick) ine fresh flux kubvisa yakawandisa solder apo saiti inoramba ichidziya. Kune dzakasindimara deposits, tembiricha-inodzorwa solder iron inobatsira kuunganidza yasara solder. Geza saiti ne isopropyl doro kana yakakodzera flux remover. Ongorora pasi pekukurisa kuti uone kuti ese mapedhi akati sandara, akachena, uye haana masikirwo akasimudzwa kana akakuvadzwa solder mask.

Kutsiva uye Soldering

Isa flux kana solder paste kune yakagadziriswa saiti uchishandisa stencils kana inodzorwa kuburitsa. Isa nzvimbo inotsiva BGA uchishandisa rework station's vision alignment system - kunyatsojeka pano kunokanganisa goho. Ita inodzorwa reflow mbiri: zvishoma nezvishoma rampu yekunyudza tembiricha, shanduko kuburikidza ne liquidus, peak tembiricha kubata, uye inodzorwa kutonhora. Dzivisa kudarika miganhu yekushisa yakatarwa nemugadziri. Bvumira gungano kuti ritonhore zvakasununguka; kutonhora kwekumanikidzirwa kunogona kukonzera kutyisa kwekupisa uye micro-cracks mumajoini ekutengesa.

Post-Rework Inspection

Simbisa BGA yega yega yakagadziridzwa kuburikidza nekutarisa kwakarongeka. Kuongorora kwemaziso pasi pekukudza kunosimbisa kurongeka kwakakodzera uye kusavapo kwezvikanganiso zvekunze. Kuongorora X-ray kunosungirwa kuongorora hunhu hwemajoini akavanzika—kutarisa maburi ari kupfuura miganhu yakatarwa, kuvharirana pakati pemabhora, zvikanganiso zvemusoro-mupiro, uye kudonha kwebhora kwakakodzera. Pedzisa nekuyedza kwemagetsi (ICT kana bvunzo inoshanda) kuti uone kuti kubatana kwese kuri kushanda mukati mezvinodiwa.

Zvinetso zvakajairika muBGA Rework

Solder Joint Defects

Solder bridging inoitika kana mabhora epadhuze asangana, achigadzira zvikabudura-zvinowanzokonzerwa nekunyanyisa solder paste, misalignment, kana kusakwana standoff urefu. Majoini anotonhora anokonzerwa nekusakwana kwekushisa kwepamusoro kana nguva yekugara, achigadzira hukama hwakasvibira, hwekristaro husina simba remuchina. Musoro-mu-pillow urema hunomuka kana chikamu uye bhodhi solder zvikatadza kubatana zvakanaka panguva yekuyerera, kazhinji nekuda kweiyo oxidation kana warpage.

Thermal Management Nyaya

PCB warpage panguva yeBGA rework inobva pakupisa kusina kuenzana kana kuwandisa kwemafuta ekupisa mukati megungano. Multi-layer boards neavo vane ndege dzinorema dzemhangura dzinoda kureba preheat phases uye nekungwarira profiling. Kukuvadzwa kwechikamu kubva mukupisa kwakanyanya kunoratidza sepakeji delamination, kufa kupwanyika, kana kuderedzwa kwemagetsi paramita. Kuyerera kwechikamu chepedyo kana kubviswa kunoitika kana kudzivirira kunoratidza kusakwana kana kusarudzwa kwenozzle kunobvumira kupisa kupararira kupfuura nzvimbo yakanangwa.

Alignment uye Pad Kukuvadzwa

Kusarongeka pakati pemabhora eBGA nePCB pads zvinokonzeresa maseketi akavhurika kana kupindirana kwepakati. Fine-pitch BGAs (0.4mm uye pazasi) inoda yakasarudzika yekuisa chaiyo-kazhinji kupfuura kugona kwemanyorero. Kusimudza mapadhi kana cratering panguva yekubviswa kwechikamu kunobva kune yakawandisa kubvisa simba, kusakwana kwe solder liquefaction, kana matambudziko agara aripo ekunamatira. Mapadhi akakuvadzwa anogona kuda micro-surgery kugadziriswa kana kuita kuti bhodhi isagadzirike.

Maitiro Akanyanya Kubudirira BGA Rework

Thermal Profile Optimization

Gadzira uye nyora ma profiles ekupisa anoenderana nemhando yega yega yePCB assembly . Zvinhu zvakasiyana-siyana zve substrate (FR-4, high-Tg, polyimide, ceramic) zvinoda nzira dzakasiyana dzekupisa. Profaili ine thermocouples dzakabatana nepamusoro peBGA nepasi pePCB kuti uve nechokwadi chekusiyana kwakakodzera kwekupisa. Dzora mwero wekupisa nekutonhodza mukati me2-4°C/sekondi kuti uderedze kushushikana kwekupisa. Simbisa ma profiles pa scrap assembly usati wagadzirisa kugadzirwa.

Process Control uye Technique

Shandisa yakakodzera flux chemistry inofananidzwa neye solder alloy-hapana-yakachena flux kune akawanda maapplication, inonyungudika mvura kana kuchenesa kwehasha kwakarongwa. Isa solder paste kana flux zvakafanana; kusapindirana kufukidzwa kunokonzera kusaenzana weti. Chengetedza saizi yakakodzera yemuromo - mipumburu inofanirwa kunge yakakura 2-5mm pane chikamu padivi. Chenesa rework midziyo nguva dzose kudzivirira kusvibiswa. Vashandi vane hunyanzvi vane dzidziso yakanyorwa vanovandudza zvakanyanya-yekutanga-pasi goho mitengo muBGA rework mashandiro.

Chengetedzo Chengetedzo yeBGA Rework

Solder uye Chemical Safety

Leaded solder (SnPb) inoda kunyatsobata kudzivirira kubuda kwemutobvu-geza maoko zvakakwana mushure mekusangana, rega kudya munzvimbo dzebasa, uye shandisa PPE yakakodzera. Lead-isina alloys (SAC305, nezvimwewo) inoda tembiricha yepamusoro, kuwedzera njodzi yekupisa. Flux fumes uye kuchenesa zvinonyungudutsa zvinoda mhepo yakakwana; exhaust yemuno parework station inotora utsi panzvimbo yacho. Tevedza zvinyorwa zvekuchengetedza data mapepa emakemikari ese anoshandiswa mukugadzirisazve maitiro.

ESD uye Equipment Safety

Electrostatic discharge dziviriro yakakosha mukati meBGA rework. Chengetedza ESD-yakachengeteka nzvimbo dzekushandira dzine meti dzakadzika, tambo dzemaoko, uye ionization pazvinenge zvakakodzera. Bata BGAs chete munzvimbo dzakatarwa ESD-dzakadzivirirwa. Kuchengetedzwa kwemidziyo kunosanganisira kubata kwakaringana mhepo inopisa nozzle (tembiricha inodarika 350 ° C panguva yekushanda), yakachengeteka PCB kugadzirisa kudzivirira kudonha kwebhodhi, uye kugara uchigadzirisa masisitimu ekudziya kuti ive nechokwadi chekuenzanisa.

mhedziso

Kugadziriswazve kweBGA inyanzvi yakakosha mukugadzirwa nekugadzirisa maPCB emazuva ano. Hunhu hwakavanzika hwemajoini eBGA solder hunoda michina yakasarudzika, kudzora kwakasimba kwemaitiro, uye kuongororwa kwakakwana padanho rega rega. Kubudirira kunoda kunzwisisa kubatana kuripo pakati pemaprofiles ekupisa, flux chemistry, uye manejimendi ekubata.

Nekutevera maitiro akanyanya akasimbiswa-kugadzirira kwakaringana, kudziyisa kunodzora, kurongeka kwakanyatso, uye kusimbiswa kwepashure-rework-vagadziri vanowana mhedzisiro yakavimbika inosangana nemhando yepakutanga yakatarwa.