[parineum]

Cycles of heating and cooling are what increases failure rates. The thermal expansion and contraction causes issues.

[rjzzleep]

Permanent heat doesn't?

[magicalhippo]

From what I've gathered, heat absolutely does[1] affect[2] it[3]:

Subsequently, in 1967, Black of Motorola experimentally derived a median time to failure (MTTF, i.e., operational lifetime) model for EM in Al interconnects, showing that the time to failure due to EM is inversely proportional to both the current density and the absolute temperature of the interconnect.

[1]: https://infinitalab.com/blog/ic-failure-analysis-defect-type...

[2]: https://resources.system-analysis.cadence.com/blog/msa2020-b...

[3]: https://www.mdpi.com/2079-9292/14/15/3151#sec3-electronics-1...