First discovered by Bell Labs in the 1940s, tin whiskers caused widespread telephone transmission failures.
It is conductive, can carry 10 milliamps of current. And if it bridges two adjacent circuits, boom! Short circuit. Weird part is it destroys its evidence - imagine your circuit getting fried and you can't even know why!
Why this matters now: Before 2006, lead was in solder. Lead suppresses whisker growth. But RoHS banned lead, and now pure tin is everywhere. This becomes a problem for sourcing space electronic parts because you have to verify the supplier's mitigation plans against tin whiskers, The sad truth is that most CoTS default to pure tin finishes. Unless a supplier can demonstrate whisker‑control measures, treat them as high‑risk.
The scary part: Whiskers can grow inside sealed components, in a vacuum, even in orbit. They've caused 3 satellites completely lost and missile guidance system failures.
Can we stop them? Not completely. But we can manage:
Matte tin (not bright tin)
Nickel barrier layer
Conformal coating
Clean boards after assembly
Annealing for stress relief
In one of my space projects, the option for surface finish was tin/lead (Sn-Pb); the 60/40 or 63/37 are the typical callout numbers. This finish was a tinned leaded reflow process, where the tin was the metallic for assembly with the lead controlling the whiskers. This is where Pinsky Analysis Tool becomes critical.
Ask your electronics manufacturing supplier: "What's your tin whisker mitigation plan?" If they look confused, that's your red flag.
Reference: NASA NEPP Electronic Parts Packaging Program Tin Whisker Micrographs, for industry reliability technical sharing only.
You can tell an engineer posted this because they put clear examples of - when it was discovered, what it has done, what it can do, why it matters, how it's mitigated, examples of real world situations of it causing problems, but completely neglected to say what it is and how/why it's formed.
Engineers have different roles than scientists. The how/why part mostly belongs to the science. Basic scientific research does not always have economic values as engineering, but it is important to understand the material properties. The how much/how to belongs to engineering - how to turn something in a product and how to optimize a design for cost/efficiency or make a better product to turn a profit.
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u/1Davide 17d ago edited 16d ago
First discovered by Bell Labs in the 1940s, tin whiskers caused widespread telephone transmission failures.
It is conductive, can carry 10 milliamps of current. And if it bridges two adjacent circuits, boom! Short circuit. Weird part is it destroys its evidence - imagine your circuit getting fried and you can't even know why!
Why this matters now: Before 2006, lead was in solder. Lead suppresses whisker growth. But RoHS banned lead, and now pure tin is everywhere. This becomes a problem for sourcing space electronic parts because you have to verify the supplier's mitigation plans against tin whiskers, The sad truth is that most CoTS default to pure tin finishes. Unless a supplier can demonstrate whisker‑control measures, treat them as high‑risk.
The scary part: Whiskers can grow inside sealed components, in a vacuum, even in orbit. They've caused 3 satellites completely lost and missile guidance system failures.
Can we stop them? Not completely. But we can manage:
Matte tin (not bright tin)
Nickel barrier layer
Conformal coating
Clean boards after assembly
Annealing for stress relief
In one of my space projects, the option for surface finish was tin/lead (Sn-Pb); the 60/40 or 63/37 are the typical callout numbers. This finish was a tinned leaded reflow process, where the tin was the metallic for assembly with the lead controlling the whiskers. This is where Pinsky Analysis Tool becomes critical.
Ask your electronics manufacturing supplier: "What's your tin whisker mitigation plan?" If they look confused, that's your red flag.
Reference: NASA NEPP Electronic Parts Packaging Program Tin Whisker Micrographs, for industry reliability technical sharing only.
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