Gaby, Check the age of the chips and the exposure time verses humidity... Many times the plating on the leads absorb moisture like the rest of the package. When heated to reflow temps the moisture vaporizes in microvoids and blows off small bits of plating and solder as the solder melts in the presence of the flux.. By baking (low and long) the PLCCs in question in dry nitrogen and duplicating your reflow process, you can get a measure of whether the problem you are having is caused by moisture or something else. Paul Edwards Process Engineering [log in to unmask] Tel: 408-433-4700 FAX: 408-433-9988 Surface Art Engineering 81Bonaventura Dr. San Jose, CA 95134 DUNS: 944740570 CAGE/NCAGE: 1XZ48 -----Original Message----- From: Gabriela Bogdan [mailto:[log in to unmask]] Sent: Friday, September 10, 2004 9:24 AM To: [log in to unmask] Subject: [TN] Tin plating on leads HELP!!! Dear friends, After assembly, on all circuits there was one fine pitch PLCC from a certain vendor which had lots of small solder balls between the leads, even on the solder mask dam between them. Other PLCC's with the same pitch were clean. We tried to see the amount of solder balls by X-ray, and found many more behind the leads. At first we thought that our solder paste was the culprit, but seeing that other components were "normal" , we looked closer to the leads by X-ray, and saw a lot of small voids only along the leads of the bad component, these voids reaching to the upper end of the leads, where the solder paste did not reach. Visually, the upper part of the leads was very rough. I suppose that the tin plating of the leads contained additives which epand during soldering, even burst out, and "spit" the molten solder all around. If this is the case,how could I reject such components during incoming inspection? Should I do a solderability test for each batch on a printed ceramic plate? Gaby --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------