I looked it up on my tables and approximately 16% of natural tin are isotopes that are radioactive, out of 10 total, and decay via isometric transistion or gamma decay, max half life is 300 days, so these are considered stable isotopes since only the radioactive portions of the 2 are produced as the result of fission fragments. The other 8 Sn isotopes are considered stable.
Pb has a similar makeup with only 4 natural isotopes and only 2 that are radioactive to a slight amount, mostly half lives of less than 2 hours, and therefore are considered stable, decay again by isometric transition and gamma, there are no alpha emmitters considered naturally occuring. There are 32 isotopes that occur thru decay chains but are NOT natrually occurring with half lives on the order of a few seconds to about 4 hours max. Pb 202, 205, and 210 are long lived radioactive isotopes but are not naturally occuring and none alpha emit they either electron capture or beta emit.
Information is from the 16th edition of chart of the nuclides by Knolls Atomic Power Laboratory.
So with that said I would look for some other contaminant in the process.
pat
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Karen Tellefsen
Sent: Tuesday, March 06, 2012 10:33 AM
To: [log in to unmask]
Subject: Re: [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER??
This is much more of a problem with tin-lead solder than SAC solder, because naturally occurring lead emits a tiny amount of alpha particles.
It's mostly an issue with BGA spheres,some of which are high lead alloys, and are often close to IC chips where the alpha emissions are most likely to cause damage.,
Karen Tellefsen - Electrical Testing
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908-791-3069
[TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER??
harvey
to:
TechNet
03/06/2012 11:58 AM
Sent by:
TechNet <[log in to unmask]>
Please respond to TechNet E-Mail Forum, harvey
Could this be true only of 63-37 or would lead-free SAC alloys also be potentially guilty of causing soft errors?
----- Forwarded Message ----
From: "Gandhi, Mahendra S (AS)" <[log in to unmask]>
To: "[log in to unmask]" <[log in to unmask]>; "[log in to unmask]" <[log in to unmask]>; "[log in to unmask]" <[log in to unmask]>
Sent: Tue, March 6, 2012 8:38:40 AM
Subject: Help. Is this true??
Evidently regular solder has decaying Uranium in it, or somehow generates alpha particles, which are being blamed for upsets. Some chips are moving to a special "low alpha" solder internally to avoid this problem on bump-grid-arrays in flipchip parts.
Mahendra Gandhi
SME - PWB Technologies
Aerospace Engineering
One Space Park, M5/1085A
Redondo Beach, Ca. 90278/*[log in to unmask]
(Office: 310.813.6857 Fax: 310.812.8630
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