Many disagree with several reasons - in my opinion, none are good. I never bond anything using 7628 preg. I use only more resin rich glass glass styles facing copper or other 7628, except 7628. Earl Moon ----- Original Message ----- From: ±è´Þ¿µ Â÷Àå ÀüÀÚ ÁõÆò°øÀåÇ°Áúº¸ÁõÆÀ <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, September 29, 1999 6:07 PM Subject: [TN] Any Opinion? > Dear Technetters ; > > I'm experiencing somewhat strange defects on 6 layerered PCBs. > The defect itself is not actually strange one because I and everyone can > easily find out it as a blister. > But the blister is only in the thin core laminate while there is not any > one between bonding layers. > The thin core laminate is composed of two 7628 prepregs. The manufactured > quality was good. > Please let me describe more details about the 6 layered PCB. > The first layer contains parts of ground and signal patterns with > adjacent 2 plies of 7628 bonding > prepreg to 2nd layer. Yes, the 2nd layer is the one copper of the thin > core laminate and > this layer plays the signal role with seldom copper lines. > The third layer contains large copper area and it means this layer is > power and ground. > I watched 14 PCBs which were rejected after reflow soldering process had > blister only in the edge > or the near point to edge. The PCBs had no blister before reflow > soldering process. > I couldn't believe that why the blister is only in the thin core laminate > and why it happened > after reflow process because the PCBs were noble ones that overcame > severe heat shock through > HSAL process. Why does the blister be connected to the edge of the PCB? > Moreover I surprised at the fact that for three times in 2 years, our > colleage has been experiencing > the same phenomena with the same construction PCBs with the other 3 PCB > houses. > Please save me from the 'blister Ghost'. > > Thanks for your attention and in advance. > > Tal Young Kim > QA Dept. > > ############################################################## > TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c > ############################################################## > To subscribe/unsubscribe, send a message to [log in to unmask] with following text in > the body: > To subscribe: SUBSCRIBE TECHNET <your full name> > To unsubscribe: SIGNOFF TECHNET > ############################################################## > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional > information. > If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or > 847-509-9700 ext.5365 > ############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################