Kev tsim tawm ntawmCov ntawv luam tawm Circuit Board (PCBs)Muaj ntau txoj kev sib txawv, ntau yam uas yuav tsum tau siv cov lasers. Kev siv UV nanosecond pulsed lasers yog nce vim qhov me thiab me apertures xav tau.
Cov khoom siv thiab cov khoom siv tau dhau los ua kev sib cog lus ua tsaug rau cov txheej txheem ntim khoom siab heev. Tom qab paub tias muaj qhov sib txawv loj ntawm lub semiconductor node thiab PCB qhov ntev - los ntawm nanometer mus rau qib millimeter nyob rau hauv cov xwm txheej hnyav - cov neeg tsim khoom txuas ntxiv tsom mus rau kev tsim cov khoom ntim qib siab los txuas cov khoom sib txawv. Ib qho kev siv thev naus laus zis no yog qhov system-hauv-pob (SiP) qhov system, qhov twg ib tus neeg sib xyaw ua ke (IC) cov khoom siv tau ntim rau hauv PCB substrate nrog cov hlau nplaum sib txuas ua ntej kev ntim khoom zaum kawg thiab sib cais. Lub architecture feem ntau suav nrog cov txheej txheem nruab nrab kom ua tiav qhov kev faib tawm ntawm cov nti sib txuas hauv PCB. Cov modules tseem tab tom npaj rau ntawm ib lub vaj huam sib luag loj thaum lub sijhawm ntim khoom zaum kawg, feem ntau yog siv epoxy molding compound (EMC) ntim lossis lwm txoj hauv kev. Tom qab ntawd cov modules sib cais siv cov txheej txheem laser txiav.
Tawm los, zoo thiab nqi yuav tsum sib phim
Lub laser zoo tagnrho rau SiP kev sib cais yog nyob ntawm cov kev cai tshwj xeeb thiab yuav tsum ua kom pom kev sib npaug ntawm kev nkag mus, qhov zoo thiab tus nqi. Thaum muaj kev cuam tshuam rau cov khoom muaj txiaj ntsig zoo, nws yuav tsim nyog siv Ultra Short Pulse (USP) lasers thiab / lossis cov teebmeem thermal tsis tshua muaj tshwm sim.UV wavelengths. Hauv lwm qhov xwm txheej, tus nqi qis dua, ntau dua kev sib tw nanosecond pulsed thiab ntev yoj lasers yog qhov kev xaiv tsim nyog dua. Txhawm rau ua kom pom kev ua haujlwm siab ntawm SiP PCB substrate txiav, MKS daim ntawv thov engineers tau sim lub zog ntsuab nanosecond pulsed laser. Spectra-Physics Talon GR70 laser tau siv los txiav cov khoom siv SiP, suav nrog nyias FR4 nrog cov xov tooj ntawm tes thiab ob lub ntsej muag soldermask, siv ntau qhov kev ua haujlwm siab nrog lub dual-axis scanning galvanometer. Tag nrho cov thickness ntawm cov khoom yog 250 µm, ntawm uas 150 µm yog (ultra-thin) FR4 daim ntawv thiab cov seem 100 µm yog ob-sided polymer soldermask. Los ntawm kev siv lub tshuab luam ntawv siab ceev ntawm 6 m / s, cov teebmeem thermal hnyav tuaj yeem txo tau thiab tsim kom muaj kev cuam tshuam rau thaj tsam cua sov (HAZ) zam. Raws li cov khoom siv nyias nyias, qhov me me focal me me (kwv yees li 16 µm, 1 / e2 txoj kab uas hla) thiab lub siab pulse repetition zaus (PRF) ntawm 450 kHz tau siv. Qhov kev sib xyaw ua ke ntawm cov kev txwv no yuav siv tag nrho cov txiaj ntsig ntawm lub laser lub peev xwm tshwj xeeb los tswj lub zog siab ntawm PRF siab (67 W ntawm 450 kHz hauv qhov piv txwv no), uas pab tswj kom muaj zog ceev thiab qhov chaw-rau-qhov sib tshooj ntawm kev soj ntsuam ceev ceev.
Txiav tsis muaj thermal degradation
Tag nrho cov net txiav ceev tau ua tiav tom qab ntau qhov kev ntsuas nrawm yog 200 mm / s. Daim duab 1 qhia txog sab nkag thiab tawm ntawm lub kerf, nrog rau thaj chaw subsurface uas txoj kev txiav hla cov hlau faus tooj liab. Ob qhov chaw nkag thiab tawm tau raug txiav kom huv si nrog me me lossis tsis muaj HAZ. Tsis tas li ntawd, lub xub ntiag ntawm tooj liab hlau tsis cuam tshuam rau cov txheej txheem txiav, thiab qhov zoo ntawm cov tooj liab kerf npoo zoo nkaus li zoo tagnrho, txawm hais tias lub kaum sab xis saib yog me ntsis txwv.
Yog xav paub ntxiv txog qhov zoo nyob ib ncig ntawm cov hlau tooj liab (thiab qhov tseeb tag nrho cov txiav), saib ntawm ntu ntu ntawm phab ntsa ntawm qhov txiav (Daim duab 2).
Qhov zoo yog zoo heev, tsuas yog ib qho me me ntawm HAZ thiab ob peb carbonized thiab particulate fragments tam sim no. Txhua fiber nyob rau hauv FR4 txheej yog kom meej meej pom, thiab cov melted feem yog nyob rau hauv lub kawg lub ntsej muag ntawm cov txiav fibers uas protrude sab nraud ntawm lub sidewalls (piv txwv li, perpendicular mus rau lub fibers uas ntev raws li qhov chaw txiav). Qhov tseem ceeb, tsis muaj delamination tuaj yeem pom hauv cov txheej txheem no.
Tsis tas li ntawd, cov txiaj ntsig tau qhia tias thaj chaw nyob ib puag ncig ntawm cov xov tooj tooj liab yog qhov zoo thiab tsis raug cuam tshuam los ntawm thermal cuam tshuam xws li tooj liab ntws los yog delamination los ntawm ib puag ncig FR4 lossis cov txheej txheem soldermask.
Thickened FR4 boards xav tau qhov chaw loj
Cutting thick FR4 for depaneling is a more mature PCB application for nanosecond pulsed lasers, where arrays of devices are separated from panels by cutting small connecting breakpoints, which was tested with the Talon GR70, for which an entirely new breakpoint cutting process was developed specifically for device panels consisting of approximately 900 µm thick FR4 boards. For this thicker material, the use of the largest possible focal spot diameter, while maintaining sufficient energy density (in J/cm2), is a key aspect of achieving the desired yield. Due to the laser's high pulse energy (>250 µJ) ntawm nominal PRF ntawm 275 kHz, qhov chaw loj dua (~ 36 µm) tau siv; Tsis tas li ntawd, cov nqaj zoo yog qhov zoo heev, nrog rau Rayleigh ntau yam ntawm cov nqaj tsom ntau tshaj 1.5 hli, uas yog 1.5 npaug ntawm cov khoom tuab. Yog li ntawd, qhov chaw me me yog qhov loj thiab tas li ntawm tag nrho cov tuab ntawm cov khoom, uas ua rau muaj txiaj ntsig zoo vim tias qhov ntim tsis sib xws ntawm cov irradiation thiab qhov tshwm sim dav grooves pab tshem tawm cov khib nyiab. Daim duab 3 qhia txog cov duab microscopic nkag thiab tawm ntawm kev txiav uas tau ua tiav siv ntau qhov kev ntsuas ceev ntawm 6 m / s (tag nrho cov net txiav ceev ntawm 20 mm / s).
Zoo ib yam li cov ntaub ntawv ntawm SiP daim hlau, qhov zoo ntawm ob sab nkag thiab tawm ntawm lub kerf yog qhov zoo heev thiab ua rau HAZ tsawg heev. Vim lub inhomogeneous xwm ntawm iav / epoxy FR4 substrate thiab lub zog tsis tshua muaj zog nyob rau hauv lub distal kawg ntawm lub laser ablation kerf, cov tawm kerf npoo feem ntau deviate me ntsis los ntawm ib tug zoo kawg nkaus txoj kab. Hla-sectional sidewall imaging qhia cov ncauj lus kom ntxaws txog qhov zoo ntawm lub kerf (Daim duab 4 hauv qab).
Hauv daim duab 4 peb tuaj yeem pom qhov ua tau zoo heev. Tsuas yog ib qho me me ntawm HAZ thiab carbon cov khoom (coke) yog tsim nyob rau hauv kev txiav. Tsis tas li ntawd, yuav luag tsis muaj melting ntawm cov iav fibers. Nrog rau kev txiav ceev txog li 20 mm / s, Talon GR70 yog qhov zoo tshaj plaws rau kev tshem tawm cov tuab FR4 PCBs, thaum tib lub sijhawm kom ntseeg tau tias muaj txiaj ntsig zoo thiab muaj txiaj ntsig siab.
