Jason Morgan wrote: > Many thanks, > > Details are as follows: > > 6 Layer 1.6 FR4 > 8" x 10" Board > > PCB support is a wasted rectangle 10mm wide along all edges, supporting PCB > at 2 or 3 points along each edge. (First observation is that this should > have copper layers)
A number of different ways to even out copper coverage on layers on opposing sides of board were mentioned, and these are probably aimed at solving residual stresses left in the board. That sounds good, but may be difficult to accomplish, dpending on board density, etc. One thing that comes to mind is that the boards come out of the laminating press flat, go through all the additional steps in PCB fabrication OK, but then warp when YOU process them to attach components. Are you sure you have to heat the boards as hot, for as long as you are doing, to get good soldering? That may have something to do with it. Finally, could you give the boards some mechanical support during the reflow soldering? Making some simple metal frames that hold the board edges during the entire time it is heated might keep them flat as they cool. Jon * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
