A Comprehensive Guide on ENIG PCB Surface Finish

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Mabhodhi edunhu akadhindwa (PCBs) anopa hwaro hwekuisa nekubatanidza zvikamu zvemagetsi muzvigadzirwa zvakasiyana-siyana kubva kumagetsi evatengi kusvika kumashandisirwo epamusoro emafoni nendege. Mapedhi emhangura akafumurwa uye matrace ari paPCB anonyorova nyore nyore kana akaiswa munzvimbo dziri pedyo, izvo zvinokanganisa zvakanyanya kuchinjika kwesimbi uye zvinoderedza kuvimbika kwechigadzirwa nekufamba kwenguva. Nokudaro, simbi inopedzwa pamusoro pesimbi inowanzo shandiswa paPCB kudzivirira zvinhu zvemhangura kubva mukusanganiswa kwesimbi uye kuwedzera kuchinjika kwesimbi.

Electroless nickel kunyudzwa goridhe (ENIG) ndeimwe yeanonyanya kufarirwa uye anosiyana-siyana PCB pamusoro pekupedzisira kushandiswa nhasi. Inopa yakanakisa solderability pamwe nekusaenzaniswa nekuora uye oxidation kuramba. Ichi chinyorwa chinopa mucherechedzo wakadzama weiyo ENIG tekinoroji uye mashandisiro ayo ekudzivirira maPCB kubva kune oxidation uku ichichengetedza yakavimbika kwenguva yakareba solderability.

Chii chinonzi ENIG PCB Surface Finish?

ENIG inoreva kuiswa kwechidimbu chegoridhe rekunyudza pamusoro pe electroless nickel plating pamapedhi emhangura uye zviteshi zvebhodhi rakadhindwa redunhu. Iyo ine mbiri-layer metallic coating iyo inokwirisa zvimiro zvenickel negoridhe kuchengetedza yakafumurwa nzvimbo dzemhangura paPCBs.

Hunhu hwakakosha hwekupedza ENIG ndeiyi:

• Electroless nickel underlayer inosvika 3-6 μm ukobvu inoiswa pekutanga paPCB copper nenzira ye autocatalytic chemical reaction.
• Izvi zvinoteverwa nekuisa yakatetepa kunyudzwa yegoridhe yepamusoro denga re 0.03-0.15 μm ukobvu pamusoro penickel layer kuburikidza ne galvanic displacement reaction.
• Iyo yepakati nickel layer inoshanda sechivharo chekuparadzira kumhangura uye zvakare inopa yakagadzikana, inotengeswa simbi hwaro.
• Iyo yekunze yegoridhe layer inoshanda kudzivirira oxidation yenickel layer uye inochengetedza yakanakisa solderability pamusoro penguva refu.
• Iyo mbiri-layer ENIG kupedzisa nekudaro inopesana neoxidation uye corrosion zvinobudirira kupa hurefu hwesherufu-hupenyu pamberi pePCB huwandu uye soldering. Iyo yekunyudza yegoridhe layer inogonesawo kuumbwa kweakavimbika solder majoini pasina chero nyaya dzekunyorova.

Uku kusanganiswa kwekupokana kwekuora uye kutengeswa kwakatanhamara kunoita kuti ENIG ive imwe yeakanyanya kuita uye akavimbika epamusoro pekupedzisira kwePCBs pane dzakasiyana siyana dzekushandisa.

Maitiro Matanho eElectroless Nickel Immersion Gold (ENIG) Plating

Iyo ENIG yekuisa maitiro inosanganisira akawanda matanho anoitwa mukutevedzana kugadzira maviri esimbi dhizaini madhipatimendi anoumba iyo ENIG kupera:

Pamusoro Kugadzirira

Ichi chikamu chekutanga chinosanganisira kunyatsocheneswa uye kuiswa kwePCB yemhangura maficha kubvisa maoiri, okisidhi uye mafirimu epamusoro anogona kutadzisa kunamatira kunamatira:

• Kuchenesa Alkaline -Izvi zvinobvisa zvimedu, magirisi uye organic zvinosvibisa uchishandisa detergent mhinduro.
• Microetching -Kunyudza nekukurumidza mu etchant senge sulfuric acid / hydrogen peroxide inoshatisa pamusoro pemhangura uye inobvisa chidimbu chepamusoro chemhangura, ichinatsiridza kunamira kweplating.
• Acid Dip -Iri nhanho rinobvisa chero asara maokisi, mafirimu epamusoro kana etching mhinduro masara anogona kusiiwa kubva pamatanho ekutanga.

Catalysation

Iyi nhanho inomutsa nzvimbo dzePCB dzemhangura mukugadzirira iyo inotevera electroless nickel plating:

• Mushonga wemvura wakanyoroveswa une palladium chloride complexes unoisa mutsetse mutete wepalladium catalyst particles panzvimbo yemhangura yemapads/traces.
• Mbeu dzepalladium dzinoshanda kutanga iyo autocatalytic deposition reaction inoshandiswa kune electroless nickel plating.
• Iyo catalyst solution inochengetwa yakatenderedza 30-50°C ine pH ye 1-3 kuti ishandiswe zvakakwana.

Electroless Nickel Plating

Iyi nhanho inosanganisira autocatalytic (hapana simba rekunze) electroless deposition yenickel layer yakatenderedza 3-6 μm ukobvu pane PCB yemhangura maficha:

• Iyo nickel plating mhinduro ine nickel sulfate sesimbi sosi pamwe neanoderedza maajenti senge sodium hypophosphite.
• Iyo plating reaction inoenderera yega pane deposition tembiricha iri pakati pe75-95 ° C zvichienderana nekuumbwa kwekugezera.
• Iyo yakapfava acidic pH ye4.5-6.0 inochengetwa kuti iwane yakakodzera plating rate.
• Iyo inokonzeresa nickel dhipoziti inopa yakanakisa solderable metallic coating ukuwo ichiita sechipinganidzo chekuparadzanisa pamusoro pemhangura.

Kunyudza Goridhe Deposition

Kutevera nickel plating, kunyudzwa kwegoridhe kuiswa kunoburitsa iyo yakatetepa inodzivirira yegoridhe yakafukidza:

• Iyo PCB pani inongonyudzwa mune acidic kunyudzwa goridhe plating mhinduro ine munyu wegoridhe.
• Iwo maion egoridhe anochinjana negalvanic maatomu enickel kuti aise ega goridhe rakatetepa rakatenderedza 0.03-0.15 μm ukobvu.
• Hapana ekunze magetsi anodiwa kusiyana ne electrolytic goridhe plating nzira.

Mushure mekuputira, nhanho dzekunyatsosuka dzinoitwa kubvisa zvisaririra zvemakemikari kubva paPCB pamusoro. Iyo bhodhi ikozvino yakagadzirira huwandu hwevanhu uye solder, neiyo ENIG kupedzisa ichidzivirira kubva kune oxidation panguva yekugadzira uye kuwedzera solder kubatana kuvimbika mumunda.

Mabhenefiti Akakosha eENIG sePCB Surface Pedzisa

ENIG plating inopa akati wandei akakosha mabhenefiti ayo anoita kuti ive imwe yeanonyanya kushandiswa PCB pamusoro pekupedzisira mukushandiswa nhasi:

• Oxidation Resistance - Iyo yakatetepa kunyudza goridhe layer inodzivirira oxidation yepasi pasi nickel layer. Izvi zvinogonesa yakanakisa sherufu-hupenyu nekurasikirwa kushoma kwekutengesa kwenguva yakareba.
• Solderability -Kunyudzwa kwegoridhe kwepamusoro kunobvumira yakavimbika uye inowirirana solder majoini kuumbwa pane ese pad nzvimbo.
• Wire Bondability - Iyo yegoridhe layer inogonesa yakakwira-goho goridhe waya yekubatanidza maseketi akabatanidzwa paENIG yakavharwa padhi remhangura paPCB.
• Pfeka Kuramba - Iyo yakaoma yegoridhe yekuputira inopikisa zvakanyanya mechanical abrasion kukuvara panguva yePCB kubata, yekubatanidza mating cycles, kadhi kuiswa nezvimwe.
• Kurwisana Kurwisana -Goridhe inopa dziviriro isingaenzaniswi kubva kune zvakakasharara zvinosvibisa maindasitiri, nharaunda dzakasvibiswa uye hunyoro/saline kushanda mamiriro.
• Kubudirira - Iyo yegoridhe yepamusoro inochengetedza yepamusoro yemagetsi conductivity pakati pemajoini pasina kana corrosion induced conductivity degradation nekufamba kwenguva.
• Coplanarity - Iyo yakaonda yunifomu yegoridhe dhipoziti inochengetedza yakanakisa pad coplanarity, iyo yakakosha pakuunganidza zvakavimbika-pitch uye isina lead zvinhu.
• Lead-isina Kuenderana - ENIG kupedzisa inoenderana zvizere neye lead-isina solder alloys, reflow profiles uye magungano maitiro.
• RoHS Kuteerana - ENIG inosangana nezvinodiwa zveRoHS zvekubvisa zvinhu zvine njodzi senge lead, zvichiita kuti ive eco-inoshamwaridzika pamusoro pekupedzisira.

Muchidimbu, ENIG kupedzisa inopa yakanyanya kutengeswa, inoitisa uye yakasimba PCB pamusoro apo ichidzivirira kubva mukuora, abrasion kana kusvibiswa pamusoro pekushandiswa kwenguva refu. Izvi zvinoita kuti ive inogadzirisa kupedzisa kwakakodzera kune akasiyana siyana ekuda maapplication.

Zvinogumira uye Zvakaipa zve ENIG Surface Finish

Ichiri kupa zvakanakisa zvivakwa, ENIG kupedzisa ine zvimwe zvinogumira uye zvinoipira:

• Mutengo wakakwira zvichienzaniswa nekunyudza tin kana organic solderability preservative (OSP) inopera sezvo ichishandisa goridhe rinodhura.
• Ukobvu hwekunyudzwa kwegoridhe layer hunoda kudzora kwakasimba pakati pe 0.03-0.15 μm, sezvo yakawandisa gobvu goridhe ine njodzi yekumisikidzwa nepo goridhe rakatetepa richipa dziviriro isina kukwana.
• Rework inonetsa pamabhodhi eENIG sezvo dhipoziti yakaoma yegoridhe iri kunetsa kupinda nesimbi dzekutengesa kubviswa kwechikamu. Complete pad metal stripping inodiwa usati watengesazve.
• Kubatana pakati penickel negoridhe layers kunokanganisa ngura, kunyanya kana paine kusvibiswa kwephosphorus. Izvi zvinogona kukonzera brittle "black pad" kukanganisa.
• Iyo electroless nickel yekugezesa kuumbwa uye plating mamiriro anoda kunyatsotarisisa uye kutonga kuti kuderedze phosphorus co-deposition pane nickel pamusoro.

Nekudaro, izvi zvipimo zve ENIG kupedzisa zvinogona kutariswa zvakanyanya kuburikidza neyakafanira maitiro ekudzora uye ukobvu optimization panguva yekuisa. Pakazere, mabhenefiti e ENIG anopfuura nekure zvipingamupinyi kune akawanda maapplication.

RoHS Kutevedza kwe ENIG Surface Finish

RoHS inomirira Restriction of Hazardous Substances, iyo inorambidza kushandiswa kwezvinhu zvine njodzi semutobvu, mercury, cadmium, hexavalent chromium nezvimwe muzvigadzirwa zvemagetsi zvinotengeswa kuEurope.

ENIG plating izere neRoHS-inoenderana nekuti maitiro acho haashandise chero chinhu chinorambidzwa mumakemikari ekuputira. Iyo yekunyudza yegoridhe yekugezera ine munyu wegoridhe senge potassium gold cyanide. Iyo electroless nickel plating kuumbwa zvakare haiunze lead kana imwe muchetura.

Nekubvisa lead uye zvimwe zvinhu zvine njodzi, ENIG inosangana neRoHS zvinodiwa zveeco-hushamwari PCB yekugadzira. Izvi zvakabatsira zvikuru mukugamuchirwa kwayo kwakapararira muvatengi, telecom, mota, zvekurapa uye zvekudzivirira zvemagetsi zvikamu.

Zvishandiso Zvinoshandiswa ENIG Plating

Iyo ENIG yekuisa maitiro inonyanya kushandisa:

• Electroless nickel plating solution ine nickel sulfate seyo nickel sosi uye inoderedza maajenti sesodium hypophosphite kuisa iyo yepakati nickel layer.
• Kunyudzwa kwegoridhe solution ine munyu wegoridhe senge potassium gold cyanide inochinjana nemaatomu enickel epamusoro kuti igadzire kunze kwegoridhe rakatetepa rinodzivirira.

Hapana zvine ngozi, zvinorambidzwa kana zvinhu zvine muchetura zvinounzwa mune imwe yematanho ekuputira. Ukobvu hwegoridhe hunochengetedzwa zvakasimba mu 0.03 kusvika 0.15 micron renji kuti uwane yakakwana solderability uye dziviriro pasina embrittlement nyaya.

Kuenzanisa Pakati pe ENIG vs HASL Surface Inopedzisa

ENIG uye inopisa mhepo solder leveling (HASL) maviri akasarudzika PCB pamusoro pekupedzisira ane misiyano yakakura:

• Process Complexity - ENIG inosanganisira matanho akawanda ekuchenesa makemikari, etching, plating etc. asi HASL inongonyudza mapuranga mune yakanyungudutswa solder inoteverwa nemhepo inopisa banga.
• Environmental - ENIG haina lead-isina uye RoHS-inoenderana nepo HASL ichibvumira kushandiswa kwevanotungamira vatengesi.
• Reparability -Kugadzirisa uye kubvisa zvikamu zviri nyore paHASL PCBs inopesana neENIG mabhodhi uko iyo goridhe layer inonetsa kupinda nekuisa simbi.
• Solderability - HASL inotambura ne solder oxidation pamusoro pehupenyu hwesherufu iyo inogona kukanganisa kunyorova. ENIG inochengetedza inowirirana solderability pamusoro pekuchengetedza kwenguva refu.
• Coplanarity - Iyo yakazunguzirwa HASL dhipoziti inopa yakashata coplanarity nepo ENIG ichipa yakanakisa flat pad pedhi.
• Temperature/Corrosion Resistance - ENIG inomira tembiricha yakakwira zvakanyanya uye nharaunda dzinoora dzichipesana neHASL.
• mutengo - HASL inzira yakachipa nepo ENIG iine yakakwira zvinhu uye mutengo wekugadzirisa nekuda kwekushandiswa kwegoridhe.

Muchidimbu, ENIG inopa kutengesa kwakanyanya, kusungirirwa uye kuramba kwezvakatipoteredza kupfuura kupedzisa kweHASL, kunyangwe nemutengo wakakwira.

Kuenzanisa ENIG uye ENEPIG Surface Inopedza

ENEPIG kupedzisa kunokwidziridza ENIG nekuunza imwe electroless palladium layer pakati pekutanga nickel plating uye yekupedzisira kunyudzwa yegoridhe layer. Izvi zvinopa akati wandei mabhenefiti achienzaniswa neENIG:

• Iyo yakatetepa palladium coating inoshanda senge inobudirira diffusion chipingamupinyi pamusoro pe nickel, iyo inobvisa njodzi yeblack pad corrosion defects iri kunetsa ENIG.
• ENEPIG inobvumira kunyudzwa kwegoridhe marata kuti aiswe sezvo palladium ichidzivirira kukanganisa kwepakati pakati pegoridhe uye nickel.
• Iyo palladium inosimbisa hukama neiyo nickel underlayer uye yekupedzisira goridhe coating, ichipa kunamira kuri nani.
• ENEPIG inoshingirira kudzokorora uye hutsinye solder excursions pamwe chete nekupisa kwakanyanyisa kuchovha bhasikoro pasina kuputika kana kudonhedza.
• Wire bonding kudhonza masimba anoratidza kuenderana kwakakura kupesana neENIG nekuda kweiyo palladium adhesion layer.

Nekudaro, ENEPIG ine mutengo wakakwira nekuda kweyekuwedzera palladium plating nhanho. Kudzora kweiyo tri-layer deposition ukobvu zvakare kunowedzera kuoma. Asi nekuvimbika kwakanyanya, ENEPIG inodarika ENIG.

Soldering Matambudziko ne ENIG Surface Finish

Nepo ENIG ichipa yakanakisa uye inowirirana solderability pamusoro penguva yakareba yekuchengetedza isati yasangana, kumwe kukanganiswa kwekutengesa kunogona kuitika:

Hazvinyorovese - Mushonga wekunyungudutsa haunyorovese zvakanaka uye unopararira pamapedhi akaputirwa neENIG panguva yekunyungudutsazve. Zvikonzero zvinogona kukonzera izvi ndeizvi:

• Ndarama yakanyura yakakora inodarika 0.15 μm. Izvi zvinodzivirira solder alloy kudyidzana ne nickel layer.
• Kusvibiswa kubva kumafuta emunwe, guruva kana makemikari panguva yekubata. Izvi zvinokanganisa kunyorova.
• Corrosion yenickel layer inobva kuplating chemistry issues. Izvi zvinoratidzira sedema pad defects izvo zvinokanganisa solderability.

Kutsemuka kweSolder - Kutsemuka mukati mezvimedu zvesolder uye majoini pamapedhi eENIG akapedzwa. Kurasikirwa kwekunamatira uku kunogona kukonzerwa ne:

• Kunyanya kuomarara kwegobvu goridhe akaturikidzana pamusoro pe 0.15 μm ukobvu izvo zvinokonzeresa kushushikana.
• Dema pad kukanganisa kugadzira isina kusimba intermetallic dunhu pakati pe solder uye pad kupera.
• Yakakwira phosphorus co-deposition munickel plating yekugezera ichidzikisa ductility.

Kuderedza

• Kudzora kwakasimba kwe ENIG layer ukobvu uye yekugezesa chemistries panguva yeplating maitiro.
• Kusimbiswa kwehukobvu hwakafanana pamaPCB uchishandisa microsectioning uye X-ray fluorescence zviyero.
• Mabatiro akakwana ekudzivirira ENIG kusvibiswa kwepasi kusati kwatengeswa.
• Solderability bvunzo uchishandisa wetting chiyero bvunzo kuona chero dzisiri-wetting nyaya.