Hi Charles - One question: I would not expect a 13x4, 0.062, 8 layer assembly to be overly "flexible" - are you experiencing the problem due to simple handling or as part of a testing or stress screening operation? Dave Hillman Rockwell Collins [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Pins popping up Author: [log in to unmask] at ccmgw1 Date: 11/12/96 10:29 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. * ***************************************************************************