Great question. I have observed voids in fillets on components other than BGAs as well. We have not studied them. Werner? > -----Original Message----- > From: TechNet [mailto:[log in to unmask]]On Behalf Of Jason Gregory > Sent: Thursday, February 14, 2002 9:06 AM > To: [log in to unmask] > Subject: [TN] Vacuolar porosity under leads > > > I have a question regarding vacuolar porosity under leads. > A potential customer has forwarded me some CAD data and will send > me some boards for me to inspect using our 5DX X-ray. His > concerns are that during reflow, the flux attempts to outgas and > stops just short of total outgassing when the joint solidifies. > This situation then forms "pockets" in the joint in the lead/pad > interconnect. > My question is this - Has anyone done any studies regarding this > phenomena and if so, does this affect the integrity of the joint? > My belief has always been that the structure and formation of the > heel portion of the joint comprises the actual integrity of the > joint and the toe fillet (or lack thereof) does not play into the > lifespan (or strength) of the joint. Therefore, the lead/pad > interconnect would also not be the main point of contention. > In Alabama, we had some components (QFP48) that had a ground lug > on the bottom part of the package that was soldered to a pad > directly beneath. The lug was approximately 1mm by 1mm and the > pad was approximately 7/10mm by 7/10mm. In this case, the > porosity dilemma was evident. We would see, through 3D > laminography, that large voids were formed, causing roughly a 40% > or so decrease in actual solder interconnect area. Some playing > around with the reflow profile displayed better results, but > never resolved the issue. > Any thoughts/comments would be greatly appreciated. > > Thanks, > > > Jason Gregory > Software Specialist > Sanmina-SCI - Tech Center Austin > 15508 Bratton Lane > Austin, Tx. 78728 > (512)246-5648 > [log in to unmask] > > ------------------------------------------------------------------ > --------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search previous postings at: www.ipc.org > On-Line Resources & > Databases > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or > 847-509-9700 ext.5315 > ------------------------------------------------------------------ > --------------- > --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------