Electronics Forum | Mon Feb 13 23:05:02 EST 2017 | swestheimer
I have been asked a very good question but have not been able to find a good answer. IPC for both PCB and PCBA refer to the X & Y dimensions to measure warp and twist but how would you determine the warp and twist for a round PCB or PCBA?
Electronics Forum | Tue Feb 14 22:20:10 EST 2017 | swestheimer
Hi Dave, Thank you for your inputs as they were good suggestions. I however let out one important detail and that this is IMS material and not glass reinforced so I think that there is more bending going on during processing than warping and twistin
Electronics Forum | Tue Jun 25 01:01:15 EDT 2002 | ianchan
Hi mates, has anyone ever done a DoE on the degree of warp PCB, after a SMT Reflow process? what were the findings and conclusion based on such a DoE? which were the critical (DoE) factors that influence the degree of warp PCB? any optimal reflow se
Electronics Forum | Wed Jun 26 21:05:15 EDT 2002 | ianchan
Hi Dave F, customer calls it "warp", we can call it "twist/bow"..etc. the "warp" occurs on individual PCB cells of 28per each panel. the overall dimension of the panel is 139mm x 168mm, and each individual PCB cell is 2.4mm x 1.2mm. Thickness is 0.
Electronics Forum | Mon Jul 01 02:42:32 EDT 2002 | ianchan
Daan: thanks for the tip.
Electronics Forum | Mon Jul 01 13:08:21 EDT 2002 | peterson
What is Tg?
Electronics Forum | Mon Jul 01 18:30:58 EDT 2002 | mcox
Remember! Empirical data will allow you to take advantage of the inherent continuity of quantitative variables.
Electronics Forum | Mon Jul 01 17:22:27 EDT 2002 | Daan Terstegge
Tg = glass transition temperature, the temperature at which the glass-epoxy starts losing it's properties as a solid material. daan
Electronics Forum | Wed Jun 26 08:53:32 EDT 2002 | davef
We have not done a DOE on board warping. Consider: * How close the board gets to its Tg during the reflow cycle * Amount of copper on each side and the balance between the two * Thickness of the board * Overall length x width * Time at temperature
Electronics Forum | Thu Jun 27 17:24:17 EDT 2002 | Daan Terstegge
Never did a DOE on that, but I think it would be quite difficult to warp a board inside the oven if it was flat when it entered the machine. If there's no center-board support then it's another story, then the board will bend due to it's own weight.
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