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/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to