Inqubo yokuhlanganisa i-surface mount isebenzisa izifanekiso njengendlela yokubeka okunembile, okuphindaphindwayo kokunamathisela kwe-solder. Isifanekiso sisho ishidi elincanyana noma elincanyana lethusi noma insimbi engagqwali elinephethini yesekethe esikwe kulo ukuze lifane nephethini yokuma yedivayisi yokukhweza ngaphezulu (SMD) ibhodi yesifunda ephrintiwe (PCB) lapho isifanekiso sizosetshenziswa khona. Ngemuva kokuthi isifanekiso sibekwe kahle futhi sifaniswe ne-PCB, i-metal squeegee iphoqa ukunamathisela kwe-solder emigodini yesifanekiso, ngaleyo ndlela yenze amadiphozi ku-PCB ukulungisa i-SMD endaweni. Idiphozithi ye-solder paste iyancibilika lapho idlula kuhhavini yokugeleza kabusha futhi ilungise i-SMD ku-PCB.

Ukwakhiwa kwesifanekiso, ikakhulukazi ukwakheka nokuqina kwayo, kanye nokuma nobukhulu bezimbobo, kunquma ubukhulu, ukuma kanye nendawo ye-solder paste deposits, okubalulekile ukuze kuqinisekiswe inqubo yokuhlanganisa ephezulu. Isibonelo, ubukhulu be-foil kanye nosayizi wokuvula wemigodi buchaza ivolumu ye-slurry efakwe ebhodini. Ukunamathiswa kwe-solder ngokweqile kungaholela ekwakhekeni kwamabhola, amabhuloho namatshe amathuna. Inani elincane le-solder paste lizokwenza ukuthi amalunga e-solder ome. Zombili zizolimaza umsebenzi kagesi webhodi lesifunda.

I-Optimum foil ukujiya

Uhlobo lwe-SMD ebhodini luchaza ubukhulu be-foil obufanele. Isibonelo, ukupakishwa kwengxenye okufana ne-0603 noma 0.020″ i-pitch SOIC kudinga ithempulethi yokunamathisela ye-solder encane, kuyilapho ithempulethi ewugqinsi ifaneleka kakhulu izingxenye ezifana no-1206 noma 0.050″ pitch SOIC. Nakuba ubukhulu besifanekiso esisetshenziselwa ukunamathisela kwe-solder sisukela ku-0.001″ ukuya ku-0.030″, ubukhulu befoil obujwayelekile obusetshenziswa kumabhodi amaningi wesekethe busukela ku-0.004″ kuye ku-0.007″.

Ubuchwepheshe bokwenza izifanekiso

Njengamanje, imboni isebenzisa ubuchwepheshe obuhlanu ukwenza i-stencils-laser cutting, electroforming, chemical etching kanye nokuxuba. Nakuba ubuchwepheshe be-hybrid buyinhlanganisela yokusikwa kwamakhemikhali nokusika i-laser, ukufakwa kwamakhemikhali kuwusizo kakhulu ekwenzeni ama-stencil anyathelwe kanye nama-hybrid stencil.

Ukufakwa kwamakhemikhali kwezifanekiso

Ukugaya amakhemikhali kufaka imaski yensimbi nesifanekiso semaski sensimbi esishintshashintshayo kusuka ezinhlangothini zombili. Njengoba lokhu kugqwala hhayi kuphela ekuqondeni mpo kodwa futhi ohlangothini olusemaceleni, kuzodala ama-undercuts futhi kwenze ukuvuleka kube kukhulu kunosayizi odingekayo. Njengoba i-etching iqhubeka kusuka ezinhlangothini zombili, ukugoqa odongeni oluqondile kuzoholela ekwakhekeni kwe-hourglass shape, okuzoholela ekufakweni kwe-solder ngokweqile.

Njengoba ukuvulwa kwe-stencil etching akukhiqizi imiphumela ebushelelezi, imboni isebenzisa izindlela ezimbili zokushelela izindonga. Enye yazo i-electro-polishing kanye ne-micro-etching process, kanti enye i-nickel plating.

Nakuba indawo ebushelelezi noma epholishiwe kusiza ukukhululwa kokunamathisela, ingase futhi ibangele ukunamathisela ukuthi kweqe ingaphezulu lesifanekiso esikhundleni sokugoqeka ne-squeegee. Umkhiqizi wesifanekiso uxazulula le nkinga ngokupholisha izindonga zembobo ngokukhetha esikhundleni sendawo yesifanekiso. Nakuba i-nickel plating ingathuthukisa ukushelela nokusebenza kokuphrinta kwesifanekiso, kunganciphisa ukuvuleka, okudinga ukulungiswa komsebenzi wobuciko.

Isifanekiso laser cutting

Ukusika i-laser kuyinqubo ekhiphayo efaka idatha ye-Gerber emshinini we-CNC olawula i-laser beam. I-laser beam iqala ngaphakathi komngcele wembobo futhi inqamule umjikelezo wayo ngenkathi ikhipha ngokuphelele insimbi ukuze yakhe imbobo, imbobo eyodwa kuphela ngesikhathi.

Imingcele eminingana ichaza ukushelela kokusika kwe-laser. Lokhu kuhlanganisa isivinini sokusika, usayizi wendawo ye-beam, amandla e-laser nokugxila kwe-beam. Imvamisa, imboni isebenzisa i-beam spot engaba ngu-1.25 mils, engasika izimbobo ezinembe kakhulu ngezinhlobonhlobo zomumo nosayizi wezidingo. Kodwa-ke, izimbobo ezisikwe nge-laser nazo zidinga ukucubungula ngemuva, njengezimbobo ezifakwe ngamakhemikhali. Izibunzi zokusika i-laser zidinga ukupholisha nge-electrolytic kanye ne-nickel plating ukuze zenze udonga lwangaphakathi lwembobo lube bushelelezi. Njengoba ubukhulu bembobo buncishiswa enqubweni elandelayo, usayizi wokuvula we-laser cutting kufanele unxeshezelwe ngendlela efanele.

Izici zokusebenzisa ukuphrinta kwe-stencil

Ukuphrinta ngama-stencil kuhilela izinqubo ezintathu ezihlukene. Eyokuqala yinqubo yokugcwalisa imbobo, lapho i-solder paste igcwalisa izimbobo. Eyesibili inqubo yokudlulisa unamathisele we-solder, lapho unamathisele we-solder oqoqwe emgodini udluliselwa endaweni ye-PCB, kanti okwesithathu indawo yokunamathisela kwe-solder efakwe. Lezi zinqubo ezintathu zibalulekile ekutholeni umphumela oyifunayo-ukufaka ivolumu enembile yokunamathisela kwe-solder (ebizwa nangokuthi isitini) endaweni efanele ku-PCB.

Ukugcwalisa izimbobo zesifanekiso nge-solder paste kudinga i-scraper yensimbi ukuze ucindezele unamathisele we-solder emigodini. Ukuqondiswa komgodi ohlobene nomugqa we-squeegee kuthinta inqubo yokugcwalisa. Isibonelo, imbobo ene-eksisi ende eqondiswe ku-stroke yeblade igcwala kangcono kunembobo ene-eksisi emfushane eqondiswe ngakuhlangothi lwe-blade stroke. Ngaphezu kwalokho, njengoba ijubane le-squeegee lithinta ukugcwaliswa kwemigodi, isivinini esiphansi se-squeegee singenza izimbobo ezine-axis ende ehambisana nokushaywa kwe-squeegee kangcono ukugcwalisa izimbobo.

Umkhawulo we-squeegee strip nawo uthinta indlela i-solder paste egcwalisa ngayo izimbobo ze-stencil. Umkhuba ojwayelekile ukuphrinta ngenkathi usebenzisa ingcindezi encane ye-squeegee ngenkathi ugcina ukusula okuhlanzekile kwe-solder paste ebusweni be-stencil. Ukwandisa ukucindezela kwe-squeegee kungalimaza i-squeegee kanye nesifanekiso, futhi kubangele ukunamathisela ukuthi kugcotshwe ngaphansi kobuso besifanekiso.

Ngakolunye uhlangothi, ingcindezi ephansi ye-squeegee ingase ingavumeli ukunamathisela kwe-solder ukuthi kukhishwe ngezimbobo ezincane, okuholela ekungeneni kwe-solder enganele kuma-PCB pads. Ngaphezu kwalokho, unamathisele we-solder oshiywe ohlangothini lwe-squeegee eduze nomgodi omkhulu ungase udonswe phansi amandla adonsela phansi, okuholela ekufakweni kwe-solder ngokweqile. Ngakho-ke, ukucindezela okuncane kuyadingeka, okuzofeza ukusula okuhlanzekile kokunamathisela.

Inani lokucindezela elisetshenzisiwe libuye lincike ohlotsheni lwe-solder paste esetshenzisiwe. Isibonelo, uma kuqhathaniswa nokusebenzisa i-tin/lead paste, uma usebenzisa i-solder-free paste, i-PTFE/nickel-plated squeegee idinga cishe u-25-40% wengcindezi eyengeziwe.

Izinkinga zokusebenza ze-solder paste nama-stencil

Ezinye izinkinga zokusebenza ezihlobene ne-solder paste nama-stencil yilezi:

Ugqinsi nosayizi wokuvula wefoyili ye-stencil inquma ivolumu engaba khona ye-solder paste efakwe kuphedi ye-PCB

Ikhono lokukhulula unamathisele we-solder odongeni lwembobo yesifanekiso

Ukunemba kwesikhundla sezitini ze-solder eziphrintwe kumaphedi e-PCB

Ngesikhathi somjikelezo wokunyathelisa, lapho umdwebo we-squeegee udlula ku-stencil, i-solder paste igcwalisa imbobo ye-stencil. Ngesikhathi somjikelezo wokuhlukanisa ibhodi/isifanekiso, ukunamathisela kwe-solder kuzokhishwa kumaphedi ebhodini. Okufanelekile, yonke i-solder paste egcwalisa imbobo ngesikhathi sokunyathelisa kufanele ikhululwe odongeni lwembobo futhi idluliselwe ku-pad ebhodini ukuze yenze isitini esiphelele se-solder. Kodwa-ke, inani lokudlulisa lincike ku-aspect ratio nesilinganiso sendawo yokuvula.

Isibonelo, esimweni lapho indawo ye-pad inkulu kunezingxenye ezimbili kwezintathu zendawo yodonga lwangaphakathi lwe-pore, ukunamathisela kungafinyelela ukukhululwa okungcono kune-80%. Lokhu kusho ukuthi ukunciphisa ukujiya kwesifanekiso noma ukukhulisa usayizi wembobo kungakhulula kangcono ukunamathisela kwe-solder ngaphansi kwenani lendawo efanayo.

Ikhono lokunamathisela i-solder ukuze likhulule odongeni lwembobo yesifanekiso nalo lincike ekuqedeni kodonga lwembobo. Izimbobo zokusika i-laser nge-electropolishing kanye/noma i-electroplating zingathuthukisa ukusebenza kahle kokudluliswa kwe-slurry. Kodwa-ke, ukudluliswa kokunamathisela kwe-solder kusuka kusifanekiso kuya ku-PCB nakho kuncike ekunamatheleni kwe-solder unamathisele odongeni lwembobo yesifanekiso kanye nokunamathela kwe-solder pad ku-PCB pad. Ukuze uthole umphumela omuhle wokudlulisa, lokhu kokugcina kufanele kube kukhudlwana, okusho ukuthi ukuphrinta kuncike esilinganisweni sendawo yodonga lwesifanekiso endaweni yokuvula, kuyilapho uziba imiphumela emincane efana ne-angle yokusalungiswa yodonga kanye nokuqina kwayo. .

Ukuma nokunemba kobukhulu bezitini ze-solder eziphrintwe kumaphedi e-PCB kuncike kukhwalithi yedatha ye-CAD edlulisiwe, ubuchwepheshe kanye nendlela esetshenziselwa ukwenza ithempulethi, kanye nezinga lokushisa lesifanekiso ngesikhathi sokusetshenziswa. Ngaphezu kwalokho, ukunemba kwesikhundla nakho kuncike endleleni yokuqondisa esetshenzisiwe.

Isifanekiso esinozimele noma ithempulethi enamathiselwe

Isifanekiso esinefreyimu okwamanje siyisifanekiso esinamandla kakhulu sokusika i-laser, esiklanyelwe ukuphrinta isikrini esikhulu ohlelweni lokukhiqiza. Zifakwe unomphela kuhlaka lwe-formwork, futhi ifreyimu ye-mesh iqinisa ngokuqinile i-formwork foil ku-formwork. Ku-BGA encane kanye nezingxenye ezine-pitch ye-16 mil nangaphansi, kunconywa ukusebenzisa ithempulethi enefreyimu enodonga olubushelelezi lwembobo. Uma isetshenziswa ngaphansi kwezimo zokushisa ezilawulwayo, isikhunta esinefreyimu sinikeza indawo engcono kakhulu nokunemba kobukhulu.

Ngokukhiqizwa kwesikhashana esifushane noma umhlangano we-PCB oyisibonelo, izifanekiso ezingenasici zinganikeza ukulawula kwevolumu yokunamathisela kwe-solder engcono kakhulu. Zenzelwe ukusetshenziswa namasistimu okuqinisa i-formwork, okungamafreyimu asebenziseka kabusha, njengamafreyimu ajwayelekile. Njengoba isikhunta singanamatheli unomphela ohlakeni, ishibhile kakhulu kunesikhunta sohlobo lwefreyimu futhi sithatha indawo yokugcina encane kakhulu.