Tin Whiskers, everything we think you should need to know
Welcome to our weekly blog! We’re steering this week towards other structures that our coatings protect against that aren’t normally asked about, unless of course, your product needs protected from it. A good comparison here would be medications. For example, most of the time this particular one medication is used for disease A1 but it can be used for illness B2 with the same if not better results.
What are Tin Whiskers?
Tin whiskers are an electrically conductive, crystalline structures of tin that sometimes grow from surfaces where tin is used as a final finish. Numerous electronic system failures have been attributed to short circuits caused by tin whiskers that bridge closely-spaced circuit elements maintained at different electrical potentials. This would be the same as not taking those medications, or using our coating services in this case.
Don’t get them confused
People sometimes confuse these tin whiskers with a more familiar occurrence known as “dendrites” formed by electrochemical migration processes. A tin whisker, though, generally has the shape of a very thin, single filament or hair-like protrusion that emerges outward from a surface. While dendrites look like a fern or snowflake patterns growing along a surface instead of outward from it. It’s similar to confusing Tylenol for Excedrin, does almost the same thing but doesn’t completely take that migraine away.
There are 4 general risks associated with Tin Whiskers.
Stable short circuits in low voltage, high impedance circuits. In these circuits there may be insufficient current available to fuse the whisker open and a stable short circuit results.
Transient short circuits. At atmospheric pressure, if the available current exceeds the fusing current of the whisker, the circuit may only experience a transient glitch as the whisker fuses open.
Metal Vapor Arc
If a tin whisker initiates a short in an application environment possessing high levels of current and voltage, then a very destructive occurrence known as Metal Vapor Arc could occur. In a metal vapor arc, the solid metal whisker is vaporized into a plasma of highly conductive metal ions.
Debris/Contamination. Whiskers or parts of whiskers may break loose and bridge isolated conductors or interfere with optical surfaces.
How to protect against Tin Whiskers
Conformal Coatings over a whisker prone surface can help reduce the risk of electrical short circuits caused by whiskers. The choice of coating material, thickness, and possible degradation over time/environmental exposure can also impact the effectiveness of the coating.
Contact us to find out how we can stop your Tin Whiskers today!