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Heavy thiab Heav Heev rau Kev Pab Ntau Tshaj Tawm Nyob Hauv PCB Tsim Thiab Fabrication
Jul 05, 2018

Ntau yam khoom siv hluav taws xob hluav taws xob muaj tsim los tsim txhua txhua hnub rau ib thaj tsam ntawm kev siv. Ua ke, cov kev kawm no yog ua kom zoo dua ntawm kev loj hlob zoo hauv kev lag luam luam tawm ntawm lub rooj laj kab ua lag luam: cov tooj liab thiab tooj liab PCBs.

Dab tsi yog qhov uas muaj nuj nqis tooj liab? Feem ntau cov PCBs muag tau tsim rau cov kev siv qis-qis-qis-zog, nrog cov qauv tooj liab / dav hlau ua los ntawm cov tooj liab tooj li ntawm ½-oz / ft2 rau 3-oz / ft2. Ib qho hnyav tooj liab yog tsim nrog tooj liab tes taw nyob qhov twg ntawm 4-oz / ft2 rau 20-nws / ft2. Qhov sib npaug ntawm qhov nyhav dhau 20-oz / ft2 thiab mus txog 200-oz / ft2 kuj tseem ua tau thiab raug xa mus raws li tooj liab heev.

Rau cov laj thawj ntawm qhov kev sib tham no, peb yuav tsom ntsoov rau feem ntawm tooj liab. Cov kab mob hnyav ntxiv nrog rau ib qho kev tsim substrate thiab cov thicker plating hauv lub voj voog ua txaij ib zaug thaum tsis muaj kev ruaj ntseg, tsis muaj zog rau lub rooj tsav xwm hauv lub voj voog ruaj khov thiab ruaj khov.

Kev tsim kho ntawm ib txoj hauv kev hnyav tooj liab txuas ib lub rooj tsav xwm nrog cov kev pab xws li:

Ua kom endurance dua thermal hom

Thaj zog tam sim no muaj peev xwm ua tau

Ua kom muaj zog ntxiv ntawm qhov chaw sib txuas thiab hauv PTH qhov

Cov khoom siv coj los siv rau lawv cov peev txheej (piv txwv li, siab kub) tsis muaj qhov tsis ua haujlwm rau circuit

Txo cov khoom loj los ntawm kev siv ntau hom tooj liab rau ntawm tib txheej ntawm circuitry (Xam phaj 1)

Hnyav tooj liab plated vias nqa ntau dua tam sim no los ntawm lub Rooj Tswjhwm Saib thiab pab hloov cov cua sov mus rau ib qho sab nraud heatsink

On-board heatsinks ncaj qha plated mus rau lub rooj tsavxwm nplai siv mus txog 120-thooj tooj dav hlau

On-board high-power-density planar transformers

Txawm hais tias qhov tsis zoo yog qhov tsawg, nws tseem ceeb heev kom nkag siab tias qhov sib txhuam ntawm Copper Circuit txoj kev tsim kho kom txaus siab rau nws cov peev xwm thiab cov kev siv tau.

Daim duab 1: Ua piv txwv li 2-oz, 10-oz, 20-oz, thiab 30-nti tooj liab ntim rau tib txheej.

Hnyav Copper Circuit Court Siv

Txuj PCBs, txawm yog ob tog los yog multilayer, yog tsim los siv kev sib txuam ntawm cov txheej txheem thiab cov txheej txheem plating. Cov vojvoog ntawm lub vojvoog pib ua cov ntawv khov ntawm cov roj (feem ntau ntawm 0.5-oz / ft2 rau 2-nws / ft2) uas muaj etched tshem tawm cov phom tsis yuav, thiab plated ntxiv tooj liab tuab mus dav hlau, khoom siv, cov pawm thiab cov plated hauv qhov. Tag nrho cov txheej hauv lub voj voos yog laminated rau hauv ib pob ntawv uas siv cov tshuaj epoxy raws li substrate, xws li FR-4 los yog polyimide.

Lub rooj sib txuas ua ke hnyav tooj liab yog ua rau tib txoj kev, xws li kev ua haujlwm tshwj xeeb thiab kev ua kom khov, xws li high-speed / step plating thiab nyias txawv nyias. Keeb kwm, hnyav tooj liab nta tau tsim nkaus los ntawm etching tuab tooj liab-clad laminated board khoom, ua uneven taug kev sidewalls thiab unacceptable undercutting. Cov kev kho tshiab nyob rau hauv plating technology tau tso cai hnyav tooj liab nta kom muaj ua ke nrog plating thiab etching, ua rau ncaj nraim thiab negligible undercut.

Plating ntawm ib lub vojvoog tooj liab hnyav ua rau lub rooj zaum txiag kom nce siab npaum li cas ntawm cov xim hauv plated thiab ntawm kev sib tw. Nws yog tam sim no ua tau kom sib tov hnyav tooj nrog txheem nta rau ib lub rooj tsavxwm. Kev muaj txiaj ntsim zoo li suav cov lej, txo tsawg zog, kev txo me me thiab kev txuag nyiaj.

Feem ntau, high-current / high-power circuits thiab lawv cov khoom siv tswj tau tsim tawm cais ntawm cov laug cam. Teeb hnyav tooj plating ua rau nws ua tau kom muaj kev sib cog phaj siab thiab tswj cov kev sib txuas lus kom paub tias muaj ntau npaum li cas, tsis tau yooj yim pawg.

Qhov hnyav tooj liab nta yuav ua tau txuas nrog cov qauv kev sib tshuam ntawm kev sib xyaws. Heavy tooj liab thiab txheem nta tau muab tso nrog tsawg kev txwv muab tus tsim qauv thiab tshuab xa tawm tham txog kev tsim ua haujlwm thiab peev xwm ua ntej kawg tsim (Daim Duab 2).

Daim duab 2: 2-oz nta txuas cov khoom sib txuas sib txuas thaum muaj 20-oz nta tau ntim rau siab.

Tam sim no nqa tau lub peev xwm thiab kub nce

Tamsim no muaj peev xwm npaum li cas uas muaj peev xwm lub voj voos muaj kev ruaj ntseg? Qhov no yog cov lus nug feem ntau voiced ntawm designers uas xav kom teeb nruab nrab ntawm cov tooj liab hnyav rau hauv lawv qhov project. Lo lus nug no feem ntau yog teb nrog lwm lo lus nug: Cov cua kub nce siab npaum li cas tuaj yeem tiv thaiv koj txoj haujlwm? Lo lus nug no zoo li vim tias kev sov siab thiab tam sim no ntws mus hauv tes. Cia peb sim teb ob lo lus nug no ua ke.

Thaum twg tam sim no ntws raws ib txoj kab, muaj ib qho I2R (fais fab tuag) uas ua rau kub hauv cheeb tsam. Cov kab txias txias los ntawm kev xa (khoom siv rau hauv cov ntaub ntawv) thiab sib sau ua ke (mus rau qhov chaw). Yog li, kom nrhiav tau qhov siab tshaj plaws tam sim no ib qho tsis muaj kev nyab xeeb, peb yuav tsum nrhiav ib txoj kev los kwv yees lub tshav kub nce nrog kev siv tam sim no. Ib qho zoo tagnrho yuav ua kom ncav cuag lub chaw haujlwm kub lub sijhawm uas qhov nqi cua kub siab npaum li cas txias. Zoo hmoo, peb muaj ib qho qauv IPC peb siv tau los ua qauv rau qhov kev tshwm sim no.

IPC-2221A: muab xam rau tam sim no muaj peev xwm ntawm ib qho chaw khiav sab nraud [1]:

Kuv = .048 * DT (.44) * (W * Th) (.725)

Qhov twg kuv yog tam sim no (amps), DT yog qhov kub siab (° C), W yog qhov dav ntawm txoj kab (mile) thiab Th yog thickness ntawm cov kab (mil). Internal cov cim yuav tsum muab faib los ntawm 50% (kwv yees) rau tib qhov chaw ntawm cua sov. Siv cov qauv ntawm IPC peb tau tshwm sim hauv daim duab 3, uas qhia txog lub peev xwm tam sim no ntawm ob peb qhov chaw ntawm kev sib txawv hauv cheeb tsam nrog 30 ° C kub nce.

Xam phaj 3: Kwv yees li ntawm kev ntsuas qhov ntev (20˚C temp rise).

Dab tsi yog qhov uas yuav tsim tau cov cua kub nce siab yuav txawv ntawm qhov project mus rau qhov project. Feem ntau cov khoom siv hauv circuit dielectric tuaj yeem muaj peevxwm kub txog 100 ° C saum toj no, txawm tias qhov hloov ntawm qhov kub hloov no yuav tsis tsim nyog rau ntau zaus.

Circuit Court Board Lub zog thiab kev muaj peevxwm

Circuit Board board thiab designers xaiv tau los ntawm ntau yam khoom siv dielectric, los ntawm tus qauv FR-4 (operating temp 130 ° C) mus rau high-temperature polyimide (operating temp 250 ° C). Kev kub ntxhov lossis huab cua qhov teeb meem tuaj yeem hu rau cov khoom siv kab txawv, tab sis yog hais tias qhov kev tshawb fawb pom thiab cov kev hloov hauv plag yog cov qauv 1-oz / ft 2, lawv puas yuav muaj sia nyob ntev tshaj? Kev lag luam ntawm Circuit Board tau tsim ib txoj kev sim rau kev txiav txim siab thermal integrity ntawm ib qhov khoom tiav lawm. Thermal lim los ntawm ntau yam khoom tsim, sib dhos thiab kho cov txheej txheem, qhov twg qhov sib txawv ntawm cov coefficient ntawm thermal expansion (CTE) ntawm Cu thiab PWB laminate muab lub zog tsav tsheb rau kev sib zog nucleation thiab kev loj hlob rau kev ua tsis tau ntawm lub circuit. Kev ntsuas thermal voj voog (TCT) cov tshev rau kev nce hauv kev tawm tsam ntawm lub voj voog raws li nws nkag mus rau cua-cua-thermal cycling ntawm 25 ° C mus rau 260 ° C.

Ib qho kev ua haujlwm nce siab qhia tias muaj kev cuam tshuam nrog hluav taws xob ntawm cov kab nrib pleb hauv txoj kev sib tsoo tooj liab. Tus qauv tsim qauv rau qhov kev xeem no siv lub saw ntawm 32 plated through-holes, uas tau ntev tau pom tias yog qhov taw qhia tsis muaj zog tshaj plaws hauv lub voj voog thaum thermal kev ntxhov siab.

Thermal kev voj voog cov kev tshawb fawb tau ua ntawm tus qauv FR-4 nrog rau 0.8-mil rau 1.2-mile ntses plating qhia tau hais tias 32% ntawm circuits tsis tom qab yim ncig (kev nce qib 20% yog xam tsis tau). Thermal voj voog cov kev tshawb fawb tau ua rau cov ntaub ntawv coj txawv txawv qhia tias qhov kev ua hauj lwm no tsis ua hauj lwm (3% tom qab 8 voj voog rau cov cyanate ester), tab sis yog tsis tshua kim heev (5 rau 10 zaug khoom nqi) thiab nyuaj ua. Ib qho nruab nrab ntawm qhov chaw nruab nrab ntawm lub tshuab pom nruab nrab pom qhov tsawg kawg ntawm plaub thermal cycles ua ntej khoom xa tuaj, thiab pom tau ob qho ntxiv ob thermal mus rau txhua qhov kev tivthaiv kho.

Nws tsis yog ib qho tsis tsim nyog rau lub Rooj Tswjhwm Saib cov SMOBC uas tau dhau los ntawm kev kho kho thiab hloov hloov mus kom txog li 9 lossis 10 thermal cycles. Qhov TCT tau qhia meej meej qhia tias tus nqi tsis ua hauj lwm, tsis muaj teeb meem li cas cov khoom txwj laus, yuav ua tsis tsim nyog. Cov ntawv cog lus ua lag luam uas tau muab luam tawm paub tias tooj liab electroplating tsis yog ib qho kev tshawb kawm kiag-kev hloov hauv cov teeb meem tam sim no thoob lub rooj tsavxwm thiab los ntawm coob tus qhov / ntawm ntau qhov tshwm sim hauv kev sib tw tooj liab li ntawm 25% lossis tshaj rod saud. Feem ntau ntawm cov "tooj liab nyias" nyob ntawm cov phab ntsa plated-cov TCT tau qhia meej meej rau qhov no.

Siv qhov hnyav tooj liab circuits yuav txo lossis tshem tawm cov kev ua tsis tiav zoo rau nws. Plating 2-oz / ft2 ntawm tooj liab rau lub qhov phab ntsa txo tus nqi tsis ua hauj lwm rau zero (TCT tau qhia tias 0.57% tsis ua hauj lwm tus nqi tom qab yim ncig rau tus qauv FR-4 nrog tsawg kawg 2.5 mil hauv plated tooj liab). Qhov siv tau, lub voj voog tooj liab ua rau cov neeg ua hauj lwm kev ntxhov siab tso rau ntawm qhov thermal cycling.

Thermal Management

Raws li tus neeg tsim khoom siv dag zog los mus nrhiav tus nqi siab tshaj plaws thiab kev ua tau zoo los ntawm lawv cov haujlwm, cov ntawv luam tawm tau ua ntau dua thiab raug ntiab tawm mus rau ntau lub zog ntau dua. Miniaturization, kev siv cov khoom siv hluav taws xob, huab cua thiab tej yam yuav tsum tau ua kom muaj nuj nqis ntawm kev tswj hwm thermal. Qhov poob siab dua hauv daim ntawv ntawm lub tshav kub, uas feem ntau yog tsim los ntawm kev lag luam ntawm electronics, tau muab los ntawm nws qhov chaw thiab tawm mus rau ib puag ncig; txwv tsis pub, lub Cheeb Tsam yuav ua rau tsis txaus siab thiab ua tsis tiav. Txawm li cas los xij, qhov hnyav tooj liab circuits yuav pab tau los ntawm kev txo cov I2R losses thiab ua kom kub deb ntawm cov khoom muaj nqis, txo cov tsis ua rau cov nqi nce.

Yuav kom ua kom tiav cov cua sov ntawm cov hluav taws xob hauv thiab nyob ntawm lub voj voog ntawm lub rooj tsavxwm, heatsinks yog ua haujlwm. Lub hom phiaj ntawm cov pa roj carbon monoxide yog kom cov nroj tsuag tawm ntawm lub hauv paus los ntawm kev sib tsoo thiab tshem tawm cov cua sov no los ntawm kev nkag mus rau ib puag ncig. Lub cua sov los ntawm ib sab ntawm lub rooj tsavxwm (los yog qhov chaw hauv tshav kub) yog txuas los ntawm tooj liab vias (qee zaum hu ua "heat vias") mus rau ib qho chaw loj tooj liab rau sab nraud ntawm lub rooj tsavxwm.

Feem ntau, classical heatsinks yog qhov sib npaug ntawm qhov sib npaug ntawm qhov tooj liab los ntawm kev siv hluav taws xob ua los sis qee zaus, muab cov riveted los yog cij. Feem ntau heatsinks yog ua los ntawm hom tooj liab los yog txhuas. Lub rooj sib txoos sib xyaw kom haum rau classical heatsinks muaj peb txoj haujlwm hnyuv thiab cov nqi kim heev.

Yuav pib, cov hlau siv ua lub heatsink yuav tsum muab xauv los yog muab txiav kom haum. Cov txheej txheem nplaum yuav tsum tau muab txiav los yog cuam tshuam rau ib qho kev txiav txim zoo ntawm lub Rooj Tswjhwm Saib Circuit Court thiab lub heatsink. Lub sijhawm kawg, tab sis yuav tsum tau muab qhov chaw tso rau hauv PCB thiab tag nrho cov pob yuav tsum tau muab tso rau hluav taws xob thiab / los yog kev tiv thaiv kev qias neeg uas muaj nyiaj los yog lub tsho tiv no.

Feem ntau, cov txheej txheem saum toj no tsis tuaj yeem ua daim phiaj thiab yuav tsum tau ua los ntawm tes. Lub sijhawm thiab kev ua haujlwm yuav tsum ua kom tiav txoj haujlwm no yog qhov tseem ceeb, thiab cov txiaj ntsim zoo tsis zoo rau qhov txheej txheem mechanical automated. Hauv kev sib piv, built-in heatsinks yog tsim tau thaum lub sij hawm PCB txoj kev tsim thiab tsis tas muaj kev sib tham ntxiv. Hnyav tooj liab Circuit Court technology ua qhov no ua tau. Cov tshuab no tso cai rau kev sib ntxiv ntawm tuab tooj liab heatsinks zoo nyob qhov twg ntawm sab nraud ntawm lub rooj tsavxwm. Lub heatsinks yog electroplated rau ntawm qhov chaw ntom ntom thiab txuas nrog lub cua sov kev vias tsis muaj interfaces uas impede thermal conductivity.

Lwm cov txiaj ntsig yog qhov ntxiv tooj liab plating nyob rau hauv qhov kub cua txias, uas txo cov thermal ua hauj lwm ntawm lub rooj tsavxwm tsim, paub tias lawv muaj peev xwm cia siab tias tib qhov tseeb ntawm qhov tseeb thiab rov ua tau qhov tseeb hauv PCB kev tsim. Vim hais tias cov phiajcim tsis sibtham ua cov qauv uas ua rau cov kab uas ua rau cov laminate tooj liab, lawv txhim kho tagnrho zuj zus thaum piv rau cylindrical wire conductors. Qhov txiaj ntsig no yog vim muaj kev txo cov tawv nqaij thiab kev ua kom muaj zog dua qub.

On-board planars ua tau zoo heev theem nrab-rau-theem nrab thiab theem nrab-rau-theem dielectric cais vim tib lub dielectric khoom siv nyob nruab nrab ntawm txhua cov khaubncaws sab nraud povtseg, txav kom tiav encapsulation ntawm txhua tus windings. Tsis tas li ntawd, thawj cov hlua khuam tau ua rau txav tau kom cov theem ob npaug ntawm qhov sib txawv ntawm cov qauv, ua kom tsis muaj kev txwv qis. Txuj kev PCB lamination, kev siv ntau hom epoxy resins, tuaj yeem muaj kev xyuam xim sandwich mus txog 50 txheej ntawm tooj liab windings li tuab li 10-nws / ft2.

Thaum lub sij hawm ua khoom ntawm hnyav tooj liab circuits, peb feem ntau soj ntsuam nrog plating loj plates; Yog li ntawd, cov nyiaj yuav tsum tau ua hauv kev cais kev sib cais thiab cov pad sib txawv. Vim li no, cov neeg tsim qauv tsim kom muaj lub rooj tsav xwm hauv board thaum ntxov hauv cov txheej txheem tsim.

Cov khoom siv hluav taws xob siv cov khoom siv tooj liab hnyav tau siv ntau xyoo nyob rau hauv kev ua tub rog thiab kev lag luam thiab muaj zog ntxiv raws li kev siv tshuab hauv kev xaiv. Nws tau ntseeg tias kev ua lag luam yuav tsum tau ua kom tiav daim ntawv thov ntawm hom khoom ntawm lub neej yav tom ntej.

References:

1. IPC-2221A