PCB sib dhos

PCBA yog lub npe luv ntawm Printed Circuit Board Assembly, uas yog hais txog cov txheej txheem ntawm kev sib txuas cov khoom siv hluav taws xob rau ntawm PCB los ua ib lub voj voog tiav. Nws yog ib kauj ruam tseem ceeb hauv kev tsim khoom siv hluav taws xob.

Feem ntau yog Through-Hole Technology (THT), Surface Mount Technology (SMT), thiab hybrid technology. THT solders cov khoom nrog cov xov hlau ntxig rau hauv qhov, SMT solders cov khoom ncaj qha rau ntawm PCB nto, thiab hybrid technology ua ke ob qho tib si.

Cov kauj ruam suav nrog kev npaj cov khoom siv, kev tshuaj xyuas PCB, SMT (kev luam ntawv nplaum solder, kev tso cov khoom, kev sib txuas rov qab), THT (kev ua cov hlau lead, kev sib txuas nthwv dej), kev vuam, kev kuaj xyuas zoo, kev ntxuav & txheej, thiab kev sib dhos zaum kawg.

Nws txuas cov khoom sib cais raws li kev tsim qauv, ua kom muaj cov haujlwm xws li kev ua cov cim qhia thiab kev hloov pauv zog. Nws yog kauj ruam tseem ceeb los hloov kev tsim qauv mus rau hauv cov khoom siv tiag tiag.

Cov txheej txheem yooj yim zoo sib xws, tab sis nws raug kho raws li qhov nyuaj ntawm cov khoom, hom khoom sib xyaw, qhov ntau thiab tsawg ntawm kev tsim khoom, thiab lwm yam. Piv txwv li, cov khoom me me uas muaj kev ua haujlwm siab yuav ntxiv kev tshuaj xyuas tes, thaum kev tsim khoom ntau yog tsom mus rau kev ua haujlwm tsis siv neeg.

THT yog Through-Hole Technology, qhov twg cov khoom siv nrog cov xov hlau raug ntxig rau hauv cov qhov rau kev vuam. Qhov zoo: lub zog kho tshuab siab, tsim rau cov khoom siv hluav taws xob siab; Qhov tsis zoo: siv qhov chaw loj, ua haujlwm tsis zoo.

SMT yog Surface Mount Technology, nrog rau qhov zoo ntawm kev sib dhos ceev ceev, qhov me me ntawm cov khoom, tsim nyog rau kev tsim khoom tsis siv neeg, ua haujlwm tau zoo, thiab tus nqi qis.

Cov thev naus laus zis sib xyaw yog siv thaum cov khoom xav tau siv ob qho tib si THT lub zog siab / lub zog kho tshuab thiab SMT qhov ceev siab / me me, xws li cov modules fais fab nrog ob qho tib si through-hole inductors thiab surface-mount chips.

Cuam tshuam los ntawm cov nqi ntawm cov khoom sib xyaw, suav cov txheej PCB / qhov loj me / qhov nyuaj ntawm cov txheej txheem, qhov nyuaj ntawm kev sib dhos, qhov ntim ntau lawm, qhov yuav tsum tau kuaj, thiab lwm yam. Cov khoom loj dua txo cov nqi ntawm cov khoom, thaum cov txheej txheem nyuaj ua rau cov nqi nce.

Cov khoom siv hluav taws xob rau cov neeg siv khoom: tus nqi qis, qhov ceev ceev, me me; Kev tswj hwm kev lag luam: kev ruaj khov, tiv thaiv kev cuam tshuam; Cov khoom siv kho mob: qhov tseeb siab thiab kev ntseeg tau, xav tau kev ua raws li cov qauv nruj.

Cov ntaub ntawv siv ntau xws li FR-4 (cov khoom siv hluav taws xob/khoom siv zoo rau cov khoom siv dav dav) thiab CEM-1 (tus nqi qis dua tab sis kev ua tau zoo qis dua). Cov coefficient ntawm kev nthuav dav thermal cuam tshuam rau kev ntseeg tau ntawm kev sib koom ua ke; qhov sib txawv loj yuav ua rau muaj teeb meem kev ntxhov siab.

Xaiv raws li qhov nyuaj ntawm lub voj voog: ob txheej rau cov voj voog yooj yim, ntau txheej rau cov nyuaj. Ntau txheej muab ntau qhov chaw routing tab sis tus nqi siab dua, nrog rau cov kev cai nruj dua rau kev sib dhos txheej.

Cov PCBs loj dhau qhov txwv ntawm cov khoom siv; cov loj tsis txaus ua rau muaj teeb meem tuav / vuam, cuam tshuam rau kev teeb tsa ntawm cov khoom thiab kev tso cua sov tawm.

Qhov loj ntawm cov ntaub qhwv, cov duab, thiab qhov sib nrug ncaj qha cuam tshuam rau qhov zoo ntawm kev vuam. Cov ntaub qhwv me dhau ua rau cov pob qij txha qhuav; qhov sib nrug ze dhau ua rau txuas cov voj voog luv luv.

Kev ntsuas qib cua kub (HASL): tus nqi qis tab sis tsis tiaj tus, cuam tshuam rau kev sib txuas zoo; Electroless nickel immersion kub (ENIG): kev sib txuas zoo, kev raug siab, tus nqi siab; Organic solderability preservative (OSP): tiv thaiv tooj liab, tus nqi nruab nrab, cov kev cai khaws cia nruj.

Kev tshuaj xyuas pom (kos, deformation), kev sim ya / ICT (kev sib txuas), kev tshuaj xyuas metallographic (cov qauv sab hauv / plating).

Kev ntxuav kom tshem tawm cov khoom tsis huv; OSP-kho PCBs xav tau ci kom tshem tawm cov dej noo thiab tiv thaiv cov npuas soldering.

Cov ntaub ntawv tsim qauv zoo li Gerber qhia txog qhov chaw teeb tsa thiab qhov chaw ntawm lub ncoo, ua lub hauv paus rau kev sib dhos kom ntseeg tau tias tsim raws li kev tsim qauv.

Cov khoom tsis tuaj yeem ntsia tau, hluav taws xob luv luv / qhib-circuits, cuam tshuam teeb liab, tsis muaj cua sov, ua rau tsis ua haujlwm lossis muaj teeb meem kev ua haujlwm.

Kev teeb tsa cov khoom tsim nyog (tsis txhob cia cov chaw tuab/nyuaj mus txog), kev tsim cov ntaub qhwv zoo, kev sib raug zoo ntawm SMT/THT, qhov chaw, thiab kev taw qhia kom tsis txhob muaj cov ces kaum ntse thiab cov kab ntev.

Xav txog kev ua tau zoo ntawm hluav taws xob (kev sib phim ntawm cov parameter), kev sib haum xeeb ntawm pob khoom nrog cov ntaub qhwv, kev ntseeg tau, tus nqi, thiab kev ruaj khov ntawm kev muab khoom.

Cov pob khoom hla qhov (piv txwv li, DIP) rau THT, qhov chaw loj; Cov pob khoom nto (piv txwv li, SOP / BGA) rau SMT, qhov ceev siab tab sis qhov nyuaj soldering siab dua (piv txwv li, BGA xav tau kev tswj kub kom meej).

Kev vuam tsis zoo ua rau cov pob qij txha qhuav thiab vuam cuav. Cov hlau oxidized/oily xav tau kev kho ua ntej (ntxuav, tinning).

Kev siv reflow soldering haum rau cov khoom SMT; kev siv wave soldering haum rau cov khoom SMT loj thiab cov khoom loj. Cov lus qhia feem ntau hais txog cov txheej txheem sib xws.

Ua ntej-nkag-ua ntej-tawm (FIFO), tswj qhov kub/av noo (20-25 ℃, 40%-60%RH), kuaj cov qauv tsis tu ncua, thiab kuaj/khib cov khoom uas tas sij hawm/xav tias muaj teeb meem.

Kev ua haujlwm tsis zoo ntawm lub voj voog (cov kev teeb tsa tsis raug, lub chip tsis ua haujlwm), luv luv / overloads, thiab kev puas tsuaj rau PCB thiab lwm yam khoom.

Kev tshuaj xyuas pom (kev puas tsuaj, kev ua kom cov hlau lead puas), kev sim cov khoom siv hluav taws xob (multimeter/LCR meter), thiab kev sim ua haujlwm ntawm cov khoom tseem ceeb (piv txwv li, kev txheeb xyuas qhov kev pab cuam ntawm lub chip).

Kev ntxhov siab kub dhau heev yuav ua rau cov khoom sib txuas sab hauv tawg hauv cov chips lossis dielectric tawg hauv cov capacitors, ua rau parameter hloov pauv lossis ua tsis tiav. Yuav tsum tswj qhov kub thiab lub sijhawm.

Cov cim polarized (piv txwv li, capacitor ±, diode xub) tau cim rau ntawm PCB pads. Kev teeb tsa tes yuav tsum tau kuaj xyuas pom; cov khoom siv tsis siv neeg xav tau cov kev teeb tsa polarity programmed.

Yuav tsum tau tswj qhov kub/av noo (±2℃, 40%-60%RH) thiab kev tiv thaiv ESD (pem teb tiv thaiv static, cov hlua khi dab teg, khaub ncaws ua haujlwm) kom tsis txhob muaj kev hloov pauv parameter thiab ESD puas tsuaj.

Lub hauv paus ntsiab lus: Kev luam ntawv nplaum nplaum → qhov chaw muab khoom → cua sov kom yaj nplaum → txias kom nplaum. Qhov kub thiab txias: Ua ntej cua sov (1-3 ℃ / s txog 150-180 ℃), tsau (180-200 ℃, 60-120s), rov ua dua (qhov siab tshaj plaws 217-235 ℃, 30-90s), txias (3-6 ℃ / s).

Lub Ntsiab Cai: Cov kua nplaum ua ib nthwv dej, thiab cov xov hlau PCB raug nplaum thaum hla dhau. Haum rau cov khoom siv SMT loj thiab cov khoom siv SMT loj.

Daim Ntawv Thov: Tsim qauv, kho, thiab thaj chaw nyuaj rau kev siv tshuab. Kev ceev faj: Hlau soldering 20-60W, hlau soldering 0.5-1.0 hli, kub 300-350 ℃, lub sijhawm 3-5 vib nas this, ntxuav ua ntej, thiab tom qab tshuaj xyuas.

Xaiv los ntawm cov txheej txheem: Cov tshuaj nplaum tsis muaj hlau lead (Sn-Ag-Cu, 217-227 ℃) rau kev rov ua dua; cov hlau nplaum tsis muaj hlau lead/lead-free (Sn-Pb, 183 ℃ rau leaded) rau kev sib txuas nthwv dej; hlau nplaum rau kev sib txuas tes, xav txog qhov ntub thiab tus nqi.

Tswj cov txheej txheem txheej txheem (qhov kub thiab txias, lub sijhawm vuam), kho cov khoom siv, cob qhia cov neeg ua haujlwm, siv cov ntaub ntawv tsim nyog, kev tshuaj xyuas AOI / X-Ray, thiab rov ua haujlwm dua raws sijhawm ntawm cov qhov tsis zoo.

Qhov sib koom ua ke qhuav: Kho qhov kub thiab txias, ncua sijhawm, ntxuav cov chaw; Luv luv: Txo cov solder, ua kom zoo dua qhov tsim; Txuas: Kho qhov ntim ntawm cov nplaum, qhov kub thiab txias; Tsis txaus solder: Ua kom cov nplaum ntau ntxiv, ua kom zoo dua cov txheej txheem; Rough solder: Ntxiv flux, kho qhov kub thiab txias.

Lub Luag Haujlwm: Tshem tawm cov oxides, txo qhov nro ntawm qhov chaw, txhim kho qhov ntub dej. Hom: Inorganic (kev ua haujlwm siab, xeb, yuav tsum tau ntxuav), organic (kev ua haujlwm nruab nrab, xeb tsawg, yuav tsum tau ntxuav), rosin-based (feem ntau, tsis xeb, tsis ntxuav). Xaiv los ntawm cov txheej txheem thiab cov khoom

Tus nqi Tg txiav txim siab qhov tsis kam ntawm cov khoom siv cua sov. Tus qauv FR-4 muaj Tg ~ 130-140 ℃, thaum cov khoom siv high-Tg (≥170 ℃) tiv taus qhov rov ua dua ntawm 250 ℃, txo qhov kev pheej hmoo ntawm kev tawg. Cov txheej txheem tsis muaj txhuas xav tau Tg ≥ 150 ℃.

Tus qauv SMT: 4/4mil (0.1/0.1mm); Cov txheej txheem HDI ua tiav 2/2mil (0.05/0.05mm) nrog kev raug siab thiab electroless tooj liab plating.

Ua raws li IPC-7351: QFP pad dav +0.1-0.2 hli vs. qhov dav ntawm cov hlau lead; 0603 pads pom zoo 0.65 × 0.65 hli rau 0.04-0.06mg solder paste ib pad.

SAC305 uas tseem ceeb (96.5Sn/3.0Ag/0.5Cu) yaj ntawm 217 ℃, siab dua Sn-Pb eutectic (183 ℃) 34 ℃, xav tau qhov kub siab dua.

0402 Cheebtsam: 0.12mm stencil; 0.5mm suab BGA: 0.1mm stencil nrog 85% lub ncoo qhib kom tiv thaiv cov pob solder.

IPC-A-610: Cov tshuaj nplaum nplaum offset ≤25% ntawm qhov dav ntawm lub ncoo; ≤0.1 hli rau 0.4 hli suab QFP.

Cov tshuab siab kawg (piv txwv li, Fuji NXT) muaj Cpk≥1.33, XY repeatability ± 25μm, θ qhov tseeb ± 0.5 °, haum rau 0201 Cheebtsam thiab 0.3 hli suab BGA.

MLCC qhov chaw siab: 0.3-0.5N (kev pheej hmoo ntawm kev tawg ntawm qhov siab dua); QFP ua: 0.8-1.2N rau kev sib koom ua ke.

Txhim kho qhov tseeb ntawm qhov chaw (± 0.05 hli), xyuas kom meej tias qhov ntim ntawm cov khoom sib xyaw ua ke, qhov rov ua dua ntawm qhov chaw ≤3 ℃ / s kom txo qhov kub thiab txias.

Ua ntej cua sov (150-180 ℃): 1-2 ℃ / s ramp; tsau (180-210 ℃): 60-90s; reflow ncov 245-255 ℃, ≥217 ℃ rau 60-90s; txias 2-4 ℃ / s.

Nitrogen (O₂＜500ppm) txo qhov oxidation thiab txhim kho qhov ntub dej, tab sis ntxiv 15-20% rau cov nqi ua tiav, tsim nyog rau cov ntawv thov kev ntseeg siab.

IPC-A-610 Chav Kawm 3: Thaj chaw khoob ≤10% ntawm thaj chaw pob solder; cov ntawv thov tseem ceeb (piv txwv li, tsheb) xav tau ≤5%.

Ob-yoj vuam: Cov nthwv dej turbulent nkag mus rau hauv 1/3-1/2 PCB tuab; qhov siab nthwv dej du 0.5-1 hli hauv qab PCB hauv qab.

Cov dej ntws tsis huv: cov khoom khov 10%) txhim kho qhov ntub dej tab sis ua rau muaj kev pheej hmoo ntawm cov khoom seem, xav tau kev ntxuav sib xws.

Ntawm 245-255 ℃ solder lauj kaub kub, qhov ceev 1.2-1.8m / feeb; tuab tooj liab PCBs xav tau 1m / feeb rau kev sau ntawm.

Kev siv hlau tsis muaj txhuas: 350-380 ℃ qhov kub ntawm lub hau, ≤3s lub sijhawm sib cuag. Kub dhau ua rau lub ncoo nqa lossis ua rau cov hlau txhuas puas.

Cov txheej txheem sib dhos kho qhov muag (± 25μm qhov tseeb) nrog cov khoom siv rov ua dua kom ntseeg tau tias qhov sib txawv ntawm cov pob solder thiab cov ntaub qhwv ＜0.1 hli.

Ua ntej cua sov 150-180 ℃, rov ua haujlwm kub 320-350 ℃, airspeed 4-6 (20-30L / feeb) kom tsis txhob muaj kev hloov pauv hlau lead.

Cov dej: zoo rau ib puag ncig tab sis xav tau qhov kub siab (60-80 ℃), muaj kev pheej hmoo ntawm kev xeb; Cov kuab tshuaj (piv txwv li, NMP): ua haujlwm tau zoo tab sis xav tau cov khoom siv tiv thaiv kev tawg, kev txwv VOC.

IPC-TM-650: Cov khoom seem Ionic 10⁹Ω.

AOI ceev ceev npog ≥95% ntawm 0402 qhov tsis zoo ntawm cov khoom, ＞ 98% rau QFP bridging / ploj lawm cov hlau, tab sis muaj teeb meem nrog BGA sab hauv voids.

Micro-focus X-Ray ua tiav qhov kev daws teeb meem 5μm, ntes tau 0.3 hli suab BGA pob qij txha thiab 20-txheej PCB sab hauv.

Cov cuab yeej ICT uas muaj qhov tseeb siab qhib qis dua 0.1Ω, nrog rau kev tiv taus ntawm cov ntsia hlau txaj

IPC-J-STD-033: MSL theem 3 cov khoom ≤168 teev ntawm 30 ℃ / 60% RH; ci ntawm 125 ℃ rau 4-8 teev yog tias tshaj.

0603 cov pob qij txha: lub zog rub tsawg kawg nkaus ≥1.5N; QFP ua rau: lub zog shear ≥5N, ib IPC-9701.

IPC-A-600: ≤1.5%; BGA-assembled PCBs ≤0.7% kom tiv thaiv cov pob qij txha qhuav.

Cov khoom siv CMOS muaj HBM rhiab heev ＜2000V. Cov chaw tsim khoom yuav tsum tswj ＜100V static voltage nrog cov hlua khi dab teg thiab cov ionizers.

Tus nqi khoom siv 40-50%, kev ua tiav (xws li kev poob nqi) 30-40%, kev tshuaj xyuas 10-20%. Tus nqi rau ib yam khoom siab dua 30-50% dua li kev tsim khoom ntau