I would like to request for input / feedback on an interesting problem
that we are seeing sporadically in our SMT line.

Some of the PCBs, post component attach, when they are either in or
are coming out of the reflow oven are making a "crackling" noise !  We
have not identified any defects in the boards or the components yet
and we are unsure what is causing the noise.  Sometimes, we are also
hearing this noise when we take a board in our hands post SMT and try
to warp it a little !  The boards are approx 5" x 12", have components
on both sides (passives and some actives) and is not very densely
populated.  Any suggestions on what could be the reason would be
greatly appreciated !

Thanks,-Koushik Banerjee-

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