A general surface jiyya na PCB sun hada da fesa tin, OSP, nutsewar zinari, da dai sauransu. “Surface” a nan yana nufin abubuwan haɗin kan PCB waɗanda ke ba da haɗin wutar lantarki tsakanin kayan lantarki ko wasu tsarin da kewaye na PCB, kamar pads. Ko wurin haɗin yanar gizo. Solderability na danda tagulla da kanta yana da kyau sosai, amma yana da sauƙin oxidize lokacin da aka fallasa shi, kuma yana da sauƙi a gurɓata. Wannan shine dalilin da ya sa dole ne a yi maganin PCB a saman.

1. Fesa tin (HASL)

Inda na’urori masu ratsa jiki suka mamaye, siyar da igiyar ruwa ita ce mafi kyawun hanyar siyarwa. Amfani da matakin solder mai zafi (HASL, Matsayin Solder Hot-Air) fasahar jiyya ta saman ya isa ya dace da buƙatun tsari na siyarwar igiyar ruwa. Tabbas, don lokuttan da ke buƙatar ƙarfin haɗin gwiwa (musamman haɗin haɗin gwiwa), ana amfani da electroplating na nickel / zinariya sau da yawa. . HASL ita ce babbar fasahar jiyya ta saman da ake amfani da ita a duk duniya, amma akwai manyan rundunonin tuƙi guda uku waɗanda ke motsa masana’antar lantarki don yin la’akari da madadin fasahohin HASL: farashi, sabbin buƙatun tsari da buƙatun marasa jagora.

Daga ra’ayi mai tsada, yawancin kayan lantarki kamar sadarwar wayar hannu da kwamfutoci na sirri suna zama sanannen kayan masarufi. Sai kawai ta hanyar siyarwa akan farashi ko ƙananan farashi za mu iya zama marasa nasara a cikin yanayin gasa mai zafi. Bayan haɓaka fasahar haɗin gwiwa zuwa SMT, pads na PCB suna buƙatar bugu na allo da sake kwararar hanyoyin siyarwa yayin aiwatar da taro. A cikin yanayin SMA, tsarin kula da saman PCB har yanzu yana amfani da fasahar HASL da farko, amma yayin da na’urorin SMT ke ci gaba da raguwa, faɗuwar fakiti da buɗewar stencil suma sun zama ƙarami, kuma a hankali an fallasa abubuwan da ke tattare da fasahar HASL. Pads ɗin da fasahar HASL ke sarrafa ba su da kyau sosai, kuma haɗin gwiwar ba zai iya biyan buƙatun aiwatar da pads masu kyau ba. Abubuwan da ke damun muhalli galibi suna maida hankali ne kan yuwuwar tasirin gubar akan muhalli.

2. Organic Solderability Protective Layer (OSP)

Organic solderability preservative (OSP, Organic solderability preservative) wani Organic shafi ne da ake amfani da shi don hana hadawan abu da iskar shaka na jan karfe kafin soldering, wato, don kare solderability na PCB gammaye daga lalacewa.

Bayan da aka yi amfani da saman PCB tare da OSP, an samar da wani yanki na bakin ciki a saman jan karfe don kare jan ƙarfe daga iskar oxygen. Kaurin Benzotriazoles OSP gabaɗaya 100 A°, yayin da kauri na Imidazoles OSP ya fi girma, gabaɗaya 400 A°. Fim ɗin OSP a bayyane yake, ba shi da sauƙin rarrabe kasancewarsa da ido tsirara, kuma yana da wahala a gano shi. A lokacin tsarin taro (reflow soldering), OSP yana sauƙin narkewa a cikin manna mai siyar ko Flux acidic, kuma a lokaci guda an fallasa saman jan ƙarfe mai aiki, kuma a ƙarshe Sn / Cu intermetallic mahadi an kafa tsakanin abubuwan da aka gyara da pads. Sabili da haka, OSP yana da halaye masu kyau lokacin amfani da su don kula da farfajiyar walda. OSP ba ta da matsalar gurɓatar dalma, don haka yana da alaƙa da muhalli.

Iyakokin OSP:

①. Tun da OSP yana da gaskiya kuma marar launi, yana da wuya a bincika, kuma yana da wuya a gane ko an rufe PCB tare da OSP.

② OSP da kanta an rufe shi, ba ya gudanar da wutar lantarki. OSP na Benzotriazoles yana da ƙananan bakin ciki, wanda bazai iya rinjayar gwajin lantarki ba, amma ga OSP na Imidazoles, fim ɗin kariya da aka kafa yana da kauri, wanda zai shafi gwajin lantarki. Ba za a iya amfani da OSP don sarrafa filayen tuntuɓar lantarki ba, kamar saman madannai don maɓalli.

③ A lokacin aikin walda na OSP, ana buƙatar Flux mai ƙarfi, in ba haka ba ba za a iya kawar da fim ɗin kariya ba, wanda zai haifar da lahani na walda.

④ A lokacin aikin ajiya, farfajiyar OSP bai kamata a fallasa shi zuwa abubuwan acidic ba, kuma zafin jiki bai kamata ya kasance mai girma ba, in ba haka ba OSP zai canza.

3. Zinare mai nutsewa (ENIG)

Tsarin kariya na ENIG:

Ni/Au an lullube shi akan saman jan karfe ta hanyar sinadarai. Matsakaicin kauri na Layer na ciki na Ni gabaɗaya 120 zuwa 240 μin (kimanin 3 zuwa 6 μm), kuma kauri na waje na Au yana da ɗan ƙaramin ƙarfi, gabaɗaya 2 zuwa 4 μin (0.05 zuwa 0.1 μm). Ni yana samar da shinge mai shinge tsakanin solder da jan karfe. Lokacin saida, Au na waje zai narke cikin sauri a cikin solder, kuma mai siyar da Ni za su samar da haɗin tsaka-tsakin Ni/Sn. Plating na zinariya a waje shine don hana Ni oxidation ko wucewa yayin ajiya, don haka zanen zinariya ya kamata ya zama mai yawa kuma kada kauri ya zama bakin ciki sosai.

Zinare na nutsewa: A cikin wannan tsari, manufar ita ce a ajiye wani sirara mai kariyar zinari mai ci gaba. Matsakaicin babban zinari bai kamata ya kasance mai kauri ba, in ba haka ba kayan haɗin gwal ɗin za su zama daɗaɗawa sosai, wanda zai yi tasiri sosai akan amincin walda. Kamar plating na nickel, zinare na nutsewa yana da babban zafin aiki da kuma dogon lokaci. A lokacin aikin tsomawa, motsin motsi zai faru-a saman nickel, zinare ya maye gurbin nickel, amma lokacin da ƙaura ya kai wani matakin, motsin ƙaura zai tsaya kai tsaye. Zinariya yana da ƙarfin ƙarfi, juriya na abrasion, juriya mai zafi, kuma ba shi da sauƙi don oxidize, don haka zai iya hana nickel daga oxidation ko passivation, kuma ya dace da aiki a cikin aikace-aikace masu ƙarfi.

Fuskar PCB da ENIG ke kula da ita tana da lebur sosai kuma tana da kyakkyawar haɗin kai, wanda shine kaɗai ake amfani da shi don fuskar maballin. Na biyu, ENIG yana da kyakkyawan solderability, zinare zai narke da sauri a cikin narkakken solder, ta haka zai fallasa sabon Ni.

Iyakokin ENIG:

Tsarin ENIG ya fi rikitarwa, kuma idan kuna son cimma sakamako mai kyau, dole ne ku sarrafa sigogin tsari sosai. Abin da ya fi damuwa shi ne cewa saman PCB da ENIG ke kula da shi yana da saurin kamuwa da baƙar fata a lokacin ENIG ko siyarwar, wanda zai haifar da mummunan tasiri akan amincin haɗin gwiwa. Tsarin tsararrun faifan baƙar fata yana da rikitarwa sosai. Yana faruwa a mahaɗin Ni da zinariya, kuma ana bayyana shi kai tsaye azaman iskar oxygen da ta wuce kima na Ni. Zinare da yawa zai ƙwace haɗin gwiwar solder kuma ya shafi dogaro.

Kowane tsarin jiyya na saman yana da nasa fasali na musamman, kuma iyakokin aikace-aikacen kuma ya bambanta. Dangane da aikace-aikacen allo daban-daban, ana buƙatar buƙatun jiyya daban-daban. A ƙarƙashin ƙayyadaddun tsarin samarwa, wasu lokuta muna ba da shawarwari ga abokan ciniki dangane da halaye na allon. Babban dalili shine samun ingantaccen magani mai ma’ana dangane da aikace-aikacen samfur na abokin ciniki da ikon aiwatar da kamfani. s Zabi.