Electronics Forum | Mon Oct 03 22:12:53 EDT 2005 | davef
When we see warp and twist, we usually jump the fabricator for: * MLB construction (not homogeneous or unbalanced - too resin rich or poor) * Supplier process capabilities (lamination cycles) * Material selection (usually cheap and dirty), etc. War
Electronics Forum | Thu Oct 13 15:38:18 EDT 2022 | proceng1
Do you have the ability to add copper thieving or otherwise balance the design? We had a customer making LED boards with a terible inbalance. Some of the boards would "smile" so badly in the oven that the leading edge touched the top. They switche
Electronics Forum | Tue Aug 08 20:43:41 EDT 2000 | Dave F
Tom: So is warp or is it twist? They�re different problems, possibly with different sources!!! And possibly different solutions!!! Consultants to talk to are: Earl Moon (pod@vcn.com), Werner Engelmeyer (engelmaier@aol.com), Les Hymes (les.hymes@w
Electronics Forum | Fri Feb 27 10:54:38 EST 1998 | Earl Moon
REVISITING MULTILAYER DIMENSIONAL STABILITY AND LAMINATE INTEGRITY It has been said we must learn it all over again and again about every four years. I know Lee Ritchey said that to me about high speed digital circuit design. The same seems true for
Electronics Forum | Wed Jun 03 09:04:19 EDT 1998 | Steve Gregory
Hi Anthony! Earl's right, things can get rather involved when you start discussing ALL the things that affect whether or not a board is going to warp. The way I look at the issue is try to separate the warp issue into two catagories; 1. The board bei
Electronics Forum | Mon Dec 31 08:51:58 EST 2001 | davef
Warp depends on: * How close the board gets to its Tg during the solder cycle (the closer you get to the Tg the worse the warp gets) * Amount of copper on each side and the balance between the two * Thickness of the board * Overall length x width * T
Electronics Forum | Tue Jun 29 14:44:26 EDT 2010 | rgduval
There are some good suggestions here...reflow pallets, and copper balancing. We would also suggest verifying that your problem is not caused by moisture. How much time passed between first side and second side reflow, and how humid is the environme
Electronics Forum | Thu Jul 15 14:55:24 EDT 1999 | JohnW
| I'm designing a board where the parts will only fit if I do one of the following: | | 1. Put BGAs on both sides | | 2. Put BGAs on top, smt TSOPs directly underneath and using blind vias to keep the real estate on the bottom side below the BGA pa
Electronics Forum | Fri Jul 13 08:54:18 EDT 2007 | rgduval
Has your board house reviewed the PCB layer stack? Make sure that the layers are balanced in copper weight, etc? Have you tried pre-baking the boards? We just had an issue with some boards warping that have never warped before for us. It happened
Electronics Forum | Fri Jul 16 17:39:33 EDT 2010 | deanm
It is a PCB design issue where the copper patterns are not balanced among the layers. Baking the boards in order to correct the warpage will not improve it. We've had a problem with one bare board in particular warping the same way from two differen
