I have a question regarding operating temperatures. Specifically regarding bare board level. It's actually opened up dialogue here as well as with my material suppliers. What is taken into consideration when determining the operating temperature of the board? I understand most base materials have a maximum operating temp. but what characteristics (electrical, mechanical etc.) are taken into consideration when determining the operating temp of a bare circuit board with mask, legend etc.? Is it just the base material that is a concern or a combination of all co-mingled elements on the board? I have spoken to a representative at DuPont and they, for example, stated that AP material alone has a maximum operating temperature of 180C but when FR or LF coverlayer material is applied then the operating temp goes down to 105C due to the acrylic adhesive present. If this is true then wouldn't a mask applied to either a flexible or rigid board influence the operating temp? If so, is testing on each and every option(s) of materials then necessary? Or... is there a simpler method of determining the operating temp. of the bare board?  Just curious.
Thanks in advance!
Dan S.

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