In the past, I had run into glob tops, encapsulants, and molding compounds containing alumina's, and silica's emitting alpha particles - and these would be immediately on top of the sensitive portion of the chip...! Since then things have cleaned up a bit, and/or a thin layer of siloxane polyimde, or some such material could act as a alpha particle shield. Depending on the package construction, I find it very interesting that the alpha particles coming from the solder joint could pass all the way through copper, underfill?, laminate material, or encapsulant/molding compounds and introduce soft errors, since just about anything stops an alpha particle. [not denying that solder can emit] Is it REALLY the solder? Steve Creswick Sr Associate - Balanced Enterprise Solutions http://www.linkedin.com/in/stevencreswick 616 834 1883 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Tuesday, March 06, 2012 2:07 PM To: [log in to unmask] Subject: Re: [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER?? Tin whiskers is not the only issue with SAC solder in space programs. :-) -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of harvey Sent: Tuesday, March 06, 2012 12:50 PM To: [log in to unmask] Subject: Re: [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER?? Karen I think that Mahendra cannot use SAC solder in space, because of those tin whiskers. ________________________________ From: Karen Tellefsen <[log in to unmask]> To: [log in to unmask] Sent: Tue, March 6, 2012 10:32:39 AM 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 [log in to unmask] 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 ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________