Tin Pest

[zeitghost]

In the solitary article of any interest in Electronics World this month, there's a mention of tin pest...

Which is rather pertinent considering that lead free solder is up to 99% pure tin...

For the uninitiated (like me), tin pest is a property of tin that is brought on by low temperatures.

It is dependent on the purity of the tin and for 99.9% (ish) pure tin, the problem starts at 15 deg C...

Yes. That's 15 degrees C above freezing... quite warm really.

For lower grades of tin, it happens at lower temperatures.

Does anyone have any idea how important this is going to be in our Brave New LeadFree World, as brought to you by know nothing beurocrats in Brussels?

 

[zeitghost]

This

http://ap.pennnet.com/Articles/Arti...Articles&Subsection=Display&ARTICLE_ID=216209

sounds promising, in as much as silver and copper do not prevent the formation of tin pest...

And the preferred solders contain... silver and copper...

 

[DaveScott]

Use bismuth and get diamagnetism, free of charge!

 

[btrueblood]

Our group had a discussion about tin whisker formation recently, now we get to do it again regarding "tin pest". Whee!

 

[IRstuff]

Here's a great little article about this:

http://www.indium.com/drlasky/entry.php?id=310

Note that the article references an older article from 2000 about lead-free solders, so this is clearly not a new thing.

TTFN

 

[zeitghost]

Some of the pictures are quite repulsive.

Nice tin sample gets horrid blisters and is reduced to grey powder eventually.

Ah well, it all fills up the landfill...

 

[IRstuff]

One thing that the other article states about tin pest not being a problem with lead-tin solder is not quite correct.

Back in the 60's and 70's tin whiskers were common with conventional tin-lead solders because the chip leads were tin plated and the plating would grow whiskers, often shorting out adjacent pins.

TTFN