Hi Steve, I wonder if you could retrace the disappearance of the solder balls. Was it caused by switching to matte SM or is it possible that you have started to use a specific flux. Could you please send your experimental data? Thanks Jacob -----Original Message----- From: Joy, Stephen C [mailto:[log in to unmask]] Sent: Thursday, October 14, 1999 6:07 PM To: [log in to unmask] Subject: Re: [TN] matte vrs gloss LPI I would guess that matte is thought to reduce solder balls because of the high surface area. The uneven surface makes it harder for the solder balls to stick. This does not mean that solder balls are not formed, just that they will stick to leads rather than to soldermask. Or if you are lucky they will be removed by a post soldering process. I am not sure if there is any definitive data on this issue. We have run soldermask experiments with positive results at one site and the opposite at another. The solderballs have not been seen for 3 years now and we use all major brands (transparently) on the same lines. I still have the experimental data, if you are interested. Steve One of our suppliers of PWBs has requested and accross the board process deviation. They want (need?) to use gloss LPI instead of the matte finish that we specify on all our drawings. They are having problems with the matte mask peeling. I have no other details. We specify matte because it reduces inspector fatigue and improves vapor cleaning results (cosmetic). I have also heard that matte finish solder mask reduces solder balls in the SMT reflow process. I have no proof. Does any one know why this would be the case? ############################################################## 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 ##############################################################