4 ms·

Is it because of tin whiskers under vacuum and low temperature? Conditions not present here on Earth?

• nickff 5y ago
  Whiskers were an early problem, but the biggest issues right now are: - Lead-free solders don't wet/flow as well as leaded, which causes lower manufacturing yields. - Lead-free solders are generally more brittle and subject to earlier fatigue failures than leaded solders, so the lead-free units often fail prematurely (compared to leaded ones).
• InitialLastName 5y ago
  Solder whiskers are more likely at low pressure and low temp, but they happen with lead-free solder (more slowly and at a lower frequency) under standard conditions as well [1]. Given the number of connections on any given PCB, and that we have no way to prevent or predict whiskers, the failure rate over reasonable time-frames of any ROHS PCBA converges to 100%. [1] https://nepp.nasa.gov/whisker/reference/tech_papers/2005-dadonna-nuclear-reactor-shutdown.pdf https://nepp.nasa.gov/whisker/reference/tech_papers/2005-dad...
• compumike 5y ago
  Tin whiskers also occur on earth at ambient temperature and pressure. I’ve personally experienced tin whiskers growing between adjacent TQFP pins (resulting in product failures). We successfully mitigated this with (1) electronic redesign so the whisker was likely to fuse (self-destruct melting via resistive heating) if it made contact with the adjacent pin in question, and (2) urethane conformal coating. NASA studies such as https://nepp.nasa.gov/whisker/reference/tech_papers/2010-Panashchenko-IPC-Tin-Whisker.pdf https://nepp.nasa.gov/whisker/reference/tech_papers/2010-Pan... show that urethane conformal coating is effective against tin whiskers. But that does add another chemical and processing step and its own hazards.