Many things can cause measeling. Some of the sources I've seen are: 1) Extreme Thermal Excursions. Like excessive HASL passes. 2) Bending or flexing the PCB while it's still hot from HASL. 3) Excessive heat from assembly. 4) Excessive rework from assembly. 5) Inadequate preheat before a thermal excursion. 6) Excessively fast heat rise during lamination.(Resin starved) 7) Thick PCBs that absorbed moisture. ...to name a few... The comment "edge of the panel" makes me wonder. Can you explain a little more indepth on this? Also...measeling is white crosses where the fiberglass bundles cross. That becomes the weakest point where fracturing occurs (or slight disbonding). Make sure we're not confusing measeling with air entrapment or delamination. Groovy -----Original Message----- From: Franklin [mailto:[log in to unmask]] Sent: Thursday, August 19, 1999 1:26 PM To: [log in to unmask] Subject: [TN] Measling Here's one for you guys, and gal's. We are witnessing measling in sporadic fashion. It usually occurs along the edge of the panel, sometimes encroaching on the boards, sometimes not. We have already contacted our supplier, for their huh hum, expertise. We pulled and reviewed again, all process records. There has been no change in the process. Verification and calibration records reflect proper equipment function. This is happening with 7629 pre-preg in 12 x 18 and 18 x 24 sizes We had pulled the material with the same lot number, the problem went away just as quick. Well, it repeated itself a week or two later, again we switched to a different batch of material, the problem went away. With the supplier on-hand, we laid up a book using pre-preg from the batch we had earlier observed measling from, as well as from another batch, there were not any measles observed, we repeated this, and again there were measles. We went back to the process, re-checked everything, still no significant changes. Our supplier has been in-house for three days running experiment's, they even brought someone in to assist him, they are just as puzzled. Samples have been sent to Microtek Labs for their analysis/opinion, no response so far. Just wondering, does anyone out there want to take a shot at this one. Thanks, Franklin D Asbell ############################################################## 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 ##############################################################