Increase/decrease of the SMT reflow preheat| 11 December, 2001
SMT Experts, Hi,
I have a pondering issue, which is :
Our current specified Reflow preheat timing is a necessary 100~140sec for the ranges of 100~170Deg-C....obtained timing is 77sec...
out of curiousity, if we further fine tune the obtained reflow preheat timing to as close as possible to the 140sec limit, will and what type of improvements can be expected? likewise, if we decrease the reflow preheat timing to as low as possible to 100sec, what can be expected?
from current visual inspections, the solder condition of post-reflow dun vary much...as a result my technicians are challenging the specs and reflow profile of the preheat seems to fluc. in the specified 100~140sec range...
My team dun want to seem difficult in terms of acceptance of agreed specs. but we do wonder about the validity of such fluctutating specs range? would like to better understand what tighter range would be better, whether to tighten towards higher 140sec or lower 100sec? and what reasons to substain this higher/lower sec range choice?
Any help and guidance would be appreciated. Thanks.