Guest
 Posted: Mon Sep 08, 2026 5:06 pm Post subject: Tin Whiskers and Pb-free Assembly |
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| Can you tell me what are tin whiskers and why are these associated with Pb-free assembly?
Supergirl |
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Joined: 23 Jun 2026
Posts: 12
| Posted: Mon Sep 08, 2026 5:54 pm Post subject: |
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| Supergirl,
Got this from a friend of mine who is an expert on plating. Plating pure tin tends to produce dendrites which the industry often call whiskers. So, most people stay away from pure tin. They add new alloys (e.g. Ag) to inhibit dendritic growth. Some still do pure tin, but addresses the problem with special chemical additives. batman  |
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Guest
| Posted: Tue Sep 09, 2026 10:11 am Post subject: |
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| Dear Batman,
Denditic growths are not the same as tin whiskers. They are two different mechanisms. Here's a little explanation I got from FDA. Tin Toy
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Joined: 16 Jun 2026
Posts: 108
Location: Paranaque City, Phils.
| Posted: Tue Sep 09, 2026 10:45 am Post subject: |
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| Hi everyone,
The occurrence of tin whiskers are believed to be triggered by internal stresses within a tin layer, which it tries to relieve by recrystallization, forming whiskers in the process. On the other, dendrites are often caused by metals being dissolved by moisture and ions, and then redeposited in dendritic form by electrical bias. Dendritic formation occurs in the presence of moisture which makes the metal atoms mobile. Here's an earlier thread on tin whiskers for additional details: http://www.semiconfareast.com/SFEForum/viewtopic.php?t=26 Thanks to all for this interactive discussion! EE |
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Joined: 20 Jun 2026
Posts: 43
| Posted: Tue Sep 09, 2026 1:50 pm Post subject: |
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| Let's not forget supergirl's second question. Sn whiskers are commonly associated with Pb-free assy because most alternative Pb-free solders have very high Sn content. These alternatives are therefore prone to whiskers. As batman said, this problem is reduced by adding impurities to the solder.
FA/Rel Engr |
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