I would also add that we have had a lot of headlight flashers fail over the years. The ones we used until the late 90's used two soldered-in relays and a 555 timer chip to drive the relays. Solder was always cracking around the relay sockets due to the weight of the relay/socket assembly "working" on the solder joints due to the vibration under the hood.

I have seen transistors unsolder themselves in high power PA assemblies, due to the heat generated in the transistor.