Tin's Real Mechanical Job Is Holding a Solder Joint Together
Solder joints fail through fatigue from thermal cycling, not static overload, and tin-based alloy design is built specifically around that failure mode.
Because over half of tin demand goes into solder, covered on this material’s application-wise page, tin’s real, practical mechanical story is about how a solder joint actually fails, not about tin’s bulk strength, which is unremarkable on its own.
Thermal cycling fatigue, not overload
A solder joint in an electronic device experiences repeated heating and cooling as the device powers on and off, and each cycle imposes a small mechanical strain as different materials in the joint expand and contract by different amounts. Solder joints fail overwhelmingly through fatigue accumulated over many such cycles, not through a single overload event, covered in more depth on copper’s mechanics page for the same general fatigue concept applied to solder specifically.
Why lead-free solder changed the mechanics, not just the chemistry
Modern tin-silver-copper (SAC) lead-free solders, adopted widely since the mid-2000s for environmental reasons, have measurably different fatigue behaviour than older tin-lead solders, generally stiffer and less forgiving of strain, a real, documented engineering trade-off the electronics industry had to design around, not a drop-in replacement.
Sources: solder fatigue mechanisms and SAC alloy behaviour draw on standard electronics packaging and materials reliability references (IPC, ASM Handbook).