T'netters,
On the matter of warped boards we are currently experiencing this problem
(warpage appears to be in either direction i.e. to the solder or component
side, sometimes exhibits and S-curve), - we do not bake these boards to
remedy but rather reject and return, hence the stand-off with the pcb
fabricator who is insistent that it is within acceptable IPC stds. PCB
details are:
* PCBs are approx. 300mm x 135mm in area,
* made of std. Duraver E-Cu 104 (Tg of 135degC) from Isola (no further
details),
* exhibits relatively good copper balance on both sides, only about
20% of the surface is coppe,.
* is only exposed to wave solder heat - it appears that the wave heat
may also worsen the problem, so it may appear that stress is already present
(on good boards) in the material before wave.
Any experience of this material, what the fabricator's process may be
inducing and any other possible contributary factors?
Advice graciously received, TIA
Grant
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