I was asked for my input on a design where the engineers want to fully pot some rigid flex pwbs with a thermal potting material that requires a cure cycle of 150C for two hours and cures to a Shore D hardness of 80.

My immediate reaction was to voice concerns over intermetallic grain structure growth but thought that I should reach out to this group of experts before responding.

We are using Sn63Pb37 solder.  The PWAs are full of reflow oven compatible components.  We normally do not expose our PWAs to any cure cycle temperatures over 110C.

Does this elevated cure cycle lower the reliability of the solder joints (more brittle)?

Will the extreme hardness of the material cause mechanical stress on the components?

Any help is appreciated.

Phil
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