I can't prove that 100C didn't damage a chip, nor can I prove that the chip was not damaged by just looking at it.

And I admit that it is possible for a bad design to physically damage a chip by such things as creating an internal bus conflict.

But your typical processor has had any bad design feature fixed, and so any damage must result from known physical stresses.

At elevated temperatures, MOS transistors become weaker, and so high internal operating currents are not going to be a problem. So any problems should arise from:

1. Increased oxide leakages, which will tend to degrade Flash and EPROM memories.

2. Metal migration occurring at an elevated rate, which will reduce lifetime far into the future.

3. At about 177C, you are at the plastic curing temperature, and that can cause package failure.

But below 125C, these problems are going to be quite rare.