A karshe shafi tsari ga PCB masana’antu sun sami canje -canje masu mahimmanci a cikin ‘yan shekarun nan. Waɗannan canje -canjen sun kasance sakamakon buƙatar da ake da ita akai -akai don shawo kan iyakokin HASL (Haɗin iska mai zafi) da haɓaka adadin hanyoyin HASL.

Ana amfani da murfin ƙarshe don kare farfajiyar murfin jan ƙarfe. Copper (Cu) wuri ne mai kyau don abubuwan haɗin waldi, amma ana sauƙaƙa shi da oxidized; Copper oxide yana hana rigar mai siyarwa. Ko da yake yanzu ana amfani da zinare (Au) don rufe jan ƙarfe, saboda zinari baya yin oxid; Zinariya da jan ƙarfe za su bazu cikin sauri kuma su mamaye juna. Duk wani jan karfe da aka fallasa da sauri zai samar da oxide na jan ƙarfe wanda ba a iya narkewa ba. Approachaya hanya ita ce amfani da nickel (Ni) “Layer Layer” wanda ke hana zinare da jan ƙarfe daga canja wuri kuma yana ba da ɗorewa, shimfidar wuri don haɗuwa da ɓangarori.

Bukatun PCB don murfin nickel ba electrolytic

Rufin nickel da ba na lantarki ba yakamata yayi ayyuka da yawa:

Farfajiyar ajiyar zinariya

Babban makasudin da’irar shine ƙirƙirar haɗin gwiwa tare da babban ƙarfin jiki da kyawawan halaye na lantarki tsakanin PCB da abubuwan da aka gyara. Idan akwai wani oxide ko gurɓatawa akan farfajiyar PCB, wannan haɗin gwiwar da aka haɗa ba zai faru tare da kwararar raunin yau ba.

Zinare yana adanawa a zahiri akan saman nickel kuma baya yin oxidation yayin tsawon ajiya. Koyaya, zinaren baya tsayawa akan nickel wanda aka ƙone, don haka dole ne nickel ya kasance mai tsabta tsakanin wankin nickel da rushewar zinaren. Don haka, abin da ake buƙata na farko na nickel shine ya kasance ba tare da isashshen oxygen ba tsawon lokaci don ba da damar zinare ya yi sauri. Abubuwan da aka ƙera sun haɓaka wanka na lemun tsami don ba da damar abun cikin phosphorus 6 ~ 10% a cikin hazo na nickel. Wannan abun cikin phosphorus a cikin murfin nickel ba electrolytic ana ɗauka azaman daidaitaccen ma’aunin kula da wanka, oxide, da kayan lantarki da na zahiri.

taurin

Ana amfani da filayen nickel da ba a rufe da su ba a cikin aikace-aikace da yawa waɗanda ke buƙatar ƙarfin jiki, kamar jigilar jigilar mota. Abubuwan da PCB ke buƙata sun yi ƙasa da ƙarfi fiye da na waɗannan aikace-aikacen, amma wani taurin yana da mahimmanci don haɗin waya, lambobin taɓawa, masu haɗin haɗin-haɗin gwiwa, da dorewar aiki.

Haɗin gubar yana buƙatar taurin nickel. Rashin gogayya na iya faruwa idan gubar ta lalace da hanzari, wanda ke taimakawa gubar ta “narke” cikin substrate. Hotunan SEM sun nuna babu shigar azzakari cikin farfajiyar nickel/zinariya ko nickel/palladium (Pd)/zinariya.

Halayen lantarki

Copper shine ƙarfe na zaɓi don ƙirƙirar kewaya saboda yana da sauƙin yi. Copper yana sarrafa wutar lantarki fiye da kusan kowane ƙarfe (tebur 1) 1,2. Zinariya kuma tana da ingantacciyar wutan lantarki, yana mai sa ta zama cikakkiyar zaɓi don ƙaramin ƙarfe saboda electrons sukan yi ta kwarara a saman hanyar da ke gudana (fa’idar “farfajiya”).

Tebur 1. Resistivity na PCB karfe

Copper 1.7 (gami da Ω cm

Zinariya (gami da 2.4 Ω cm

Nickel (gami da 7.4 Ω cm

Non-electrolytic nickel shafi 55 ~ 90 ω ω cm

Ko da yake halayen wutar lantarki na yawancin faranti na samarwa ba su shafi nunin nickel ba, nickel na iya shafar halayen lantarki na siginar mitar mitar. Rashin siginar PCB na microwave na iya wuce ƙayyadaddun zanen. Wannan sabon abu ya yi daidai da kaurin nickel – da’irar tana buƙatar wucewa ta cikin nickel don isa wurin siyarwa. A aikace -aikace da yawa, ana iya dawo da siginar lantarki zuwa ƙayyadaddun ƙira ta ƙayyade adon nickel na ƙasa da 2.5µm.

Sadarwar lamba

Tsayayyar lamba ta bambanta da walda saboda farfajiyar nickel/zinariya ba ta da daɗi a cikin rayuwar ƙarshen samfurin. Nickel/zinare dole ne ya kasance yana gudana don saduwa da waje bayan tsawan lokacin muhalli. Littafin Antler na 1970 ya bayyana buƙatun lamba na nickel/zinariya a cikin sharuddan adadi. Anyi nazarin wurare daban-daban na amfani: 3 “65 ° C, matsakaicin matsakaicin zafin jiki don tsarin lantarki da ke aiki a zafin jiki na ɗaki, kamar kwamfutoci; 125 ° C, yanayin zafin da dole ne masu haɗin duniya su yi aiki, galibi ana ƙayyade su don aikace -aikacen soja; 200 ° C, wannan zafin yana ƙara zama mahimmanci ga kayan tashi. ”

Don ƙarancin yanayin zafi, ba a buƙatar shinge na nickel. Yayin da zafin jiki ke ƙaruwa, adadin nickel da ake buƙata don hana canja wurin nickel/zinare yana ƙaruwa (Table II).

Tebur 2. Tsayayyar lamba ta nickel/zinariya (awanni 1000)

Nickel shãmaki Layer gamsarwa lamba a 65 ° C gamsarwa lamba a 125 ° C gamsarwa lamba a 200 ° C

0.0 µm 100% 40% 0%

0.5 µm 100% 90% 5%

2.0 µm 100% 100% 10%

4.0 µm 100% 100% 60%

Nickel ɗin da aka yi amfani da shi a binciken Antler an ƙera shi da lantarki. Ana tsammanin haɓakawa daga nickel ba electrolytic, kamar yadda Baudrand 4 ya tabbatar. Duk da haka, waɗannan sakamakon na zinariya ne na 0.5 wherem, inda jirgin yakan saba da 0.2 µm. Ana iya ƙaddara jirgin don isa ga abubuwan tuntuɓar da ke aiki a 125 ° C, amma abubuwan zafin jiki mafi girma zasu buƙaci gwaji na musamman.

Antler ya ba da shawarar, “kauri mai kauri, shine mafi kyawun shinge, amma a zahiri, amma gaskiyar masana’antar PCB tana ƙarfafa injiniyoyi su saka nickel kawai yadda ake buƙata. Flat nickel/zinariya yanzu ana amfani da shi a cikin wayoyin salula da shafukan da ke amfani da wuraren tuntuɓar taɓawa. Ƙayyadaddun nau’in wannan nau’in shine aƙalla 2 µm nickel.

Mai haɗawa

Ana amfani da nutsewar baƙin ƙarfe na nickel/zinare a cikin ƙera allon kewaye tare da fitowar bazara, latsa-fitarwa, zamewar matsin lamba da sauran masu haɗawa da ba a haɗa su ba.

Masu haɗin plug-in suna buƙatar dorewar jiki. A cikin waɗannan lamuran, murfin nickel da ba na lantarki ba yana da ƙarfi don aikace-aikacen PCB, amma nutsewar zinare ba. Zinariya tsantsa mai bakin ciki (60 zuwa 90 Knoop) za ta goge daga nickel yayin maimaita gogayya. Lokacin da aka cire zinaren, nickel da aka fallasa yana yin oxidation cikin sauri, wanda ke haifar da ƙaruwa cikin juriya.

Rufin nickel wanda ba na lantarki ba/nutsewar zinare na iya zama ba shine mafi kyawun zaɓi don masu haɗin plug-in waɗanda ke jure abubuwan da yawa a cikin rayuwar samfurin. Nickel/palladium/zinariya saman ana ba da shawarar su don masu haɗa abubuwa da yawa.

Layen katangar

Nickel ba electrolytic yana da aikin yadudduka uku na shinge akan farantin: 1) don hana yaduwar jan ƙarfe zuwa zinare; 2) Don hana yaduwar zinariya zuwa nickel; 3) Tushen nickel da Ni3Sn4 mahaɗan intermetallic mahadi suka kafa.

Rarraba jan ƙarfe zuwa nickel

Canja wurin jan ƙarfe ta hanyar nickel zai haifar da rugujewar tagulla zuwa saman zinare. Tagulla za ta yi oxide da sauri, wanda ke haifar da rashin walƙiya yayin taro, wanda ke faruwa a yanayin zubin nickel. Ana buƙatar nickel don hana ƙaura da watsa faranti marasa amfani yayin ajiya da lokacin taro lokacin da aka haɗa wasu sassan farantin. Sabili da haka, buƙatun zafin jiki na Layer shinge bai wuce minti ɗaya a ƙasa da 250 ° C ba.

Turn da Owen6 sunyi nazarin tasirin yadudduka daban -daban akan jan ƙarfe da zinare. Sun gano cewa “… Kwatanta dabi’un haɓakar jan ƙarfe a 400 ° C da 550 ° C yana nuna cewa chromium hexavalent da nickel tare da abun ciki na phosphorus 8-10% sune mafi kyawun shingen shinge da aka yi nazari “. (tebur 3).

Teburi na 3. Zurfin jan ƙarfe ta hanyar nickel zuwa zinariya

Kauri na Nickel 400 ° C 24 hours 400 ° C 53 hours 550 ° C 12 hours

0.25 µm 1 µm 12 µm 18 µm

0.50 µm 1 µm 6 µm 15 µm

1.00 µm 1 µm 1 µ M 8 µm

2.00 µm Ba watsawa ba watsawa ba watsawa

Dangane da lissafin Arrhenius, watsawa a ƙananan yanayin zafi yana da saurin a hankali. Abin sha’awa, a cikin wannan gwajin, nikel ɗin da ba na lantarki ba ya ninka sau 2 zuwa 10 fiye da nickel ɗin da aka zaɓa. Juya kuma Owen ya nuna cewa “… A (8%) 2µm (80µinch) katangar wannan gami yana rage watsa jan ƙarfe zuwa matakin sakaci. ”

Daga wannan matsanancin gwajin zafin jiki, kaurin nickel na aƙalla 2µm amintaccen bayani ne.

Rarraba nickel zuwa zinariya

Abu na biyu da ake buƙata na nickel da ba na lantarki ba shine nickel baya ƙaura ta hanyar “hatsi” ko “ramuka masu kyau” waɗanda aka yi wa zinare. Idan nickel ya sadu da iska, zai oxidize. Nickel oxide ba mai siyarwa bane kuma yana da wahalar cirewa tare da juyawa.

Akwai labarai da yawa kan nickel da zinare da ake amfani da su azaman masu ɗaukar guntun yumbu. Waɗannan kayan suna tsayayya da matsanancin yanayin taro na dogon lokaci. Gwajin gama gari na waɗannan saman shine 500 ° C na mintina 15.

Don kimanta ikon filaye da ba na lantarki ba nickel/zinare da aka yi wa zinare don hana haɓakar nickel, an yi nazarin walƙiya na saman-yawan zafin jiki. An gwada zafi/zafi daban -daban da yanayin lokaci. Waɗannan binciken sun nuna cewa nickel yana da isasshen kariya ta hanyar zinare, yana ba da damar walƙiya mai kyau bayan tsufa.

Rarraba nickel zuwa zinare na iya zama abin iyakancewa don haɗuwa a wasu lokuta, kamar haɗaɗɗen waya na thermalsonic. A cikin wannan aikace -aikacen, fuskar nickel/zinari ba ta da ci gaba fiye da saman nickel/palladium/gwal. Iacovangelo yayi bincike kan kaddarorin watsawa na palladium azaman shinge tsakanin nickel da zinari kuma ya gano cewa 0.5µm palladium yana hana ƙaura ko da a yanayin zafi. Wannan binciken ya kuma nuna cewa babu watsawar jan ƙarfe ta hanyar 2.5µm na nickel/palladium wanda Auger spectroscopy ya ƙaddara a cikin mintuna 15 a 500 ° C.

Nickel tin intergeneric fili

A lokacin hawa ko aiki na siyarwa, za a gauraye atom daga saman PCB tare da atamfa mai siyarwa, gwargwadon kaddarorin watsawar ƙarfe da ikon ƙirƙirar “mahaɗan intermetallic” (Table 4).

Tebur 4. Diffusivity na kayan PCB a walda

Zazzabi na ƙarfe ° C watsawa (µinches/ SEC.)

Zinare 450 486 117.9 167.5

Copper 450 525 4.1 7.0

Palladium 450 525 1.4 6.2

Nickel 700 1.7

A cikin tsarin nickel/zinari da tin/gubar, gwal ɗin nan da nan ya narke cikin kwano mara nauyi. Mai siyarwar yana samar da babban abin haɗewa zuwa nickel na asali ta hanyar samar da mahaɗan Ni3Sn4. Ya kamata a saka isasshen nickel don tabbatar da cewa mai siyarwar ba zai kai ƙarƙashin jan ƙarfe ba.Gwargwadon Bader ya nuna cewa ba a buƙatar fiye da 0.5µm na nickel don kula da shinge, har ma ta hanyar hawan zafin jiki sama da shida. A zahiri, matsakaicin kauri mai kauri da aka lura yana ƙasa da 0.5µm (20µinch).

porous

Nickel/zinari ba electrolytic ya zama kwanan nan ya zama abin rufe fuska na PCB na ƙarshe, don haka hanyoyin masana’antu na iya zama ba su dace da wannan farfajiya ba. Ana samun tsarin tururi na nitric acid don gwada porosity na nickel/zinariya na electrolytic da aka yi amfani da shi azaman mai haɗawa (IPC-TM-650 2.3.24.2) 9. Nickel/impregnation ba electrolytic ba zai wuce wannan gwajin ba. An haɓaka ƙa’idodin porosity na Turai ta amfani da potassium ferricyanide don tantance ƙarancin porosity na shimfidar lebur, wanda aka bayar dangane da ramuka a kowane milimita murabba’in (kwari /mm2). Kyakkyawan shimfidar wuri yakamata ya zama ƙasa da ramuka 10 a kowace murabba’in milimita a girman 100 x.

ƙarshe

Masana’antun masana’antun PCB suna da sha’awar rage adadin nickel da aka ajiye a kan jirgin saboda dalilai na farashi, lokacin sake zagayowar, da jituwa na kayan. Ƙayyadaddun ƙayyadaddun nickel yakamata ya hana hana watsa jan ƙarfe zuwa farfajiyar zinare, kula da ƙarfin ƙarfin walda mai kyau, da kiyaye ƙarancin juriya. Matsakaicin ƙayyadaddun nickel yakamata ya ba da damar sassauci a masana’antar faranti, saboda babu manyan hanyoyin gazawa waɗanda ke da alaƙa da adon nickel mai kauri.

Ga mafi yawan ƙirar ƙirar zagaye na yau, murfin nickel ba na lantarki na 2.0µm (80µinches) shine mafi ƙarancin kaurin nickel da ake buƙata. A aikace, za a yi amfani da kauri mai yawa na nickel akan yawan samarwa na PCB (Hoto 2). Canjin kaurin nickel zai haifar ne daga canjin kaddarorin sunadarai na wanka da canji a lokacin zama na injin ɗagawa ta atomatik. Don tabbatar da mafi ƙarancin 2.0µm, ƙayyadaddun bayanai daga masu amfani da ƙarshen yakamata su buƙaci 3.5µm, mafi ƙarancin 2.0µm, kuma mafi girman 8.0µm.

Wannan takamaiman kewayon kaurin nickel ya tabbatar da dacewa don samar da miliyoyin allon kewaye. Yankin ya cika waldi, rayuwar shiryayye da buƙatun tuntuɓar na’urorin lantarki na yau. Saboda buƙatun taro sun bambanta daga samfur ɗaya zuwa wani, ana iya inganta murfin saman don kowane takamaiman aikace -aikacen.