In a message dated 09/07/2000 2:29:55 PM Central Daylight Time, [log in to unmask] writes: > seen the pictures, and rad the responses. A lot of good posts. At the risk > of being redundant, her's what I've run cross as root causes for this sort > of dewetting. > > 1. LPI Solder Mask residue. Either from incomplete developing, poor rinsing > and dried in place, or redeposit from a poorly ventilated cure oven. Either > case difficult to see with naked eye prior to HASL processing. > > 2. Oxidation of copper from LPI cure bake not properly removed by preclean > for HASL (microetch). > > 3. Poor flux wetting to surface. Boards not properly dried of rinse waters > after pre-clean and prior to application of flux at HASL. Trying to flux wet > panels doesn't work well. Or poor flow of flux through the flux rollers. > > Hope this helps > > Bob Dube > > ES&D Hi Bob and Everybody! Well, had a conference call about an hour ago with our fab vendor. Not mentioning any names, and I'm not trying to trash anybody, but the call was interesting. There were a couple of people there from their side, and me, our quality engineer, and purchasing manager on our side. The conversation started by them stating that they didn't see a dewetting problem (I sent them the same pictures you looked at). They said that the reason the solder looked like that was because they use a vertical leveling machine, and that's the nature of the HASL process. They stated that they build boards for other customers and the boards all look like that and they've never had a complaint from any of their customers about solderability problems. I was kind of dumbfounded...me and our quality engineer kind of stared at each other with a big question mark over our heads. What they were saying was 180° out from the input I've gotten from everyone here. So then I asked; "You mean you disagree that those pictures don't show dewetting?" They replied; "Yes, that appearance is normal...and besides you can't say there's a problem with dewetting until you do a test like running the board over a wave or solder dipping it to see if there's really dewetting occuring." I replied; "We have boards here from other vendors that have been HASL'ed, and they don't appear like these boards do..." So I told them that I would take a board and print it with solder paste and run it through our reflow oven...that I wanted to test it that way because that's the way it would be assembled. I did, and the solder did cover the pads and adhere pretty much, however I did notice on a few pads that the solder did not flow out to the very edges of the pads. So are the boards okay? Or was I "the boy who cried wolf" on this deal? 'preciate any comments...ya' live and learn. -Steve Gregory- ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8d ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################