Charles, Does it appear that the leads are popping up during reflow or afterwards? If so, it may be popcorning. We have seen this in the past on .5 mm pitch 100 pin QFP's. Have some parts evaluated using acoustic microscopy to determine whether they experienced delamination. If not, it may be the lack of filleting on the solder joint. Look for any physical representation in the joint which would indicate mechanical failure after reflow. Increasing the pad dimensions will help if this is the root cause, but you may have to gang mask the resist. If so, use caution as your solder apertures may also have to change. Hope this help, Allen Hertz [log in to unmask] (954) 846-5829 ______________________________ Reply Separator _________________________________ Subject: Pins popping up Author: [log in to unmask] at ftl03 Date: 11/12/96 11:20 PM Technet: I have a board about 13.5" x 4.5" (PC plug in card), .062" thick, 8 layer, FR4, 1 oz copper, 2 power planes, with 16 100 pin TQFP packages (0.5mm lead pitch) spread across the board (2 rows of 8), as well as many other PLCC and SOIC devices. The problem we are having with these prototypes is that some pins on the TQFP's pop up durring handling. The boards seem to be too flexable, which probably causes the pins to break off the pads. Is there a way to make the board more rigid besides using board stiffiners? In other words can anything be done as far as changing the board stack up, or will using thicker copper help this situation? Or are there different types of FR4 available? Or is there something I am not looking at? Also, what would be a good pad size for the 100 pin TQFP chip? Currently I am using 1.2mm x .25mm, but I think the IPC recommends 1.6mm x .35mm, but it doesn't look like it would allow any soldermask between pads. Or does anybody even bother with soldermask between pads at .5mm pitch? What is the middle ground? Thanks in advance! Charles Wills [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************