Are you using Lead free solder?

[Paul Barker]

"Tin whiskers is a phenomenon or fault which occurs in electrical devices. Tin whiskers were noticed and documented in the valve era of electronics early in the 20th century, in equipment which used pure, or almost pure tin solder in their production. It was noticed that small metal hairs grew between metal solder pads causing short circuits. The problem was solved with the addition of lead which prevents the growth of the hairs. The European union banned the use of lead in most consumer products in the early 21st century due to health problems associated with lead, leading to a re-emergence of the problem. New laws exclude some medical equipment and space flight hardware, which can still use solders which contain lead.

Whiskers can cause short circuits and arcing in electrical equipment. The phenomenon was discovered by telephone companies in the late 1940s and it was later found that the addition of lead to tin solder provided mitigation, but the European Restriction of Hazardous Substances Directive (RoHS), that took effect on July 1, 2006, restricted the use of lead in various types of electronic and electrical equipment. This has driven the use of lead-free alloys.

Tin whiskers often cause failures in relays, and have been found upon examination of failed relays in nuclear power facilities.
The increase in use of pure tin in electronics due to the RoHS directive drove JEDEC and IPC to release a tin whisker acceptance testing standard and mitigation practices guideline intended to help manufacturers reduce the risk of tin whiskers in lead-free products."

[IslandPink]

I remember seeing something about this in documentation for an optical unit we were building recently. In the electronics section of the specification there were comments about tin whiskers and NOT using lead-free solder.

[Mike H]

Paul where did that come from?

[pre65]

Talking about whiskers, when I were a lad (before proper 2 stroke oils), plug whiskers were a common occurrence on my Lambretta.

[Paul Barker]

In my world of work we are finding boiler pcb's a lot more unreliable. When researching the problem, one of the lads has a friend who works on nuclear submarines where they have stopped using lead free solder so he googled it and came up with what I copied, I think he got it from Wicki.

Another example of Nanny European state intervention for the worse.

[Mike H]

It is interesting, obviously could be a problem with PCB pads close together.

What Phil was alluding to is high Voltage encourages whiskering as well, even with leaded solder. Things like EHT connections for CRT's "unsoldering" themselves, not an unknown problem in the TV repairers' world.