Tin Whiskers are a major problem in the design of electronic circuits and the manufacturing of electronic hardware.
What are Tin Whiskers? How can electronic products be design to mitigate the issue of Tin Whiskers?
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asked Feb 8, 2015 at 13:07
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1$\begingroup$ related: What are tin whiskers and what causes them? $\endgroup$– Nick AlexeevFeb 8, 2015 at 21:31
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$\begingroup$ My initial thought was that different alloys might be an option, Maybe the right alloy hasn't been found yet. 2nd thought was maybe electrical attraction or magnetic fields where influencing the alignment of whiskers from one conductor to another, but that was just a wild thought from nowhere. 3rd thought is maybe Cu needs to be replaced with another metal on printed circuit boards to reduce the stresses in pure Sn solder. An interesting dilemma. $\endgroup$– FredFeb 11, 2015 at 7:36
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$\begingroup$ Your references appear to actually answer much (perhaps all) of this question. Would it be possible for you to write up a relatively concise answer yourself, using those references, instead of attaching them to the question? $\endgroup$– AirFeb 13, 2015 at 20:30
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1 Answer
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What are tin whiskers?
The easy explanation is that Tin Whiskers are tiny threads of tin that grow out of lead-free tin soldier. They are a problem because they can cause electrical shorts at random times. They can begin to grow from weeks to years after a part is produced.
The exact causes of tin whiskers are not known, but their growth seems to be caused by internal stresses in the tin that work to push out the thin whiskers. Since the issues are caused by the internal structure of the tin, analyzing the basic material properties is hard.
Tin is not the only material that has whiskers. Metallic whiskers have also been researched in zinc, cadmium, indium, silver, aluminum, and gold.
How to mitigate tin whiskers?
From this article from EE Times and this article from Electronics Design, the following are strategies in order of mitigating the root cause to mitigating the effects:
- Don't use pure tin.
- Use a matte tin finish instead of a bright tin finish.
- Anneal the tin after plating.
- Refinish the part with a hot-solder dip.
- Apply a conformal coating. These are special coatings that help to contain the whiskers as they form. They also can help to insulate board components from being shorted by whiskers.
