Bing - I'm not sure I fully understand what you are saying but let me respond by saying that for large IC's (QFP's, BGA's, PLCC's, etc.) you can get some unsoldered joints due to board warpage and poor lead coplanarity. Among several causes, the most common board warpage problems I've seen during reflow are usually due to uneven copper distribution in buried power and ground planes of multilayer boards. Unfortunately, the drawing you said you had attached to the email was not included on the TechNet distribution. Ed Valentine Electronics Manufacturing Solutions 8612 Mourning Dove Road, Raleigh, NC 27615 Phone: (919) 270-5145, Fax: (919) 847-9971 Email: [log in to unmask] Website: http://www.ems-consulting.com ----- Original Message ----- From: "Milanie Racuya" <[log in to unmask]> To: <[log in to unmask]> Sent: Monday, August 28, 2000 9:33 PM Subject: [TN] unsoldered joint > Guys, good day > I've got some queries regarding warpage of the PCBA after reflow which > could cause unsoldered joint on one of the IC's. Almost 20% of the lower > left corner of the board is removed and I think that the tension is not > evenly distributed. Is this idea correct? Please see attached drawing > for you guys to visualize what I'm trying to tell you. > > Thanks, > Bing > > ############################################################## > 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 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 1.8c ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################