LEADFREE Archives

March 2010

Leadfree@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Pratap Singh <[log in to unmask]>
Reply To:
(Leadfree Electronics Assembly Forum)
Date:
Mon, 1 Mar 2010 13:21:58 -0600
Content-Type:
multipart/mixed
Parts/Attachments:
text/plain (1879 bytes) , text/plain (8 kB)
Hi Werner,

 

Thanks. 

The CAF and general metal migration in PCB has been described in details on
pages 68, 86, 223 and 225 in Failure Modes and Mechanisms in Electronic
Packages' co-authored by me and Viswam. The other terms that have been used
by various authors are - dendritic growth, conductive migration, conductive
corrosion migration, filament formation, Electromigration etc. These make
and break mechanisms are exhibited by Ag, Au, Pb, Cu, and Sn commonly used
in PCB assembly and packages. My comments were more to the point that in
addition to Tin Whiskers (a LF issue), other mechanisms are available to
cause a shorting failure. We all need well documented failure analysis of
parts from a failed Toyota. Should IPC take a lead and provide a helping
hand to Toyota to get to the bottom of these events?

 

 

pratap singh

___________________________________

Tel/Fax: 512-255-6820; Cell: 512-663-8903

email: [log in to unmask]

 



______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

-------------------------------------------------------------------------------Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL)
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-------------------------------------------------------------------------------


 Hi Pratap, The copper migration' you describe has a name_'conductive anodic filament (CAF)'. Werner       -----Original Message----- From: Pratap Singh <[log in to unmask]> To: [log in to unmask] Sent: Fri, Feb 26, 2010 8:21 pm Subject: Re: [LF] Expert recreates Toyota sudden acceleration Chuck,   I addition to Tin Whiskers, other possible failure cause can be Copper Migration. This phenomenon also behaves like a whisker that is it will create a short, then burn out and grow again. Copper migration has occurred on PCB surface and internally (PTH to plane). I know it is not politically correct to say any thing against LF solder caused tin whisker thinking. There are few other mechanisms in PCB assembly that can cause internal surface shorts. Tin whisker is just one of the many.     pratap singh ___________________________________ Tel/Fax: 512-255-6820; Cell: 512-663-8903 email: [log in to unmask] ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ---------------------------------------------------------------------------- ---Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Leadfree To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL) Search previous postings at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ---------------------------------------------------------------------------- ---   Now that a plausible train of events has been demonstrated, i.e. a intermittent short circuit as seen in previous links to demonstration videos, perhaps it would be beneficial to ask what could cause a short circuit to exist that would clear itself when the circuit is subjected to an impact stress? Having seen long tin whiskers in person, and how they did indeed short out circuitry, I am willing to 'suspend disbelief' and accept tin whiskers as a possible cause of these failures once we have evidence of tin whiskers growing in the units, but not before. Chuck Patten, PMP Engineer Lead Project -----Original Message----- From: Leadfree [mailto:[log in to unmask]] On Behalf Of Marcus L. Thompson Sent: Friday, February 26, 2010 9:39 AM To: [log in to unmask] Subject: Re: [LF] Expert recreates Toyota sudden acceleration "Doing whatever we can to call attention to this possibility in the public eye is crucial." Because the public has essentially no knowledge of this new and particularly insidious failure mode for electronic systems (tin whiskers), it's important that we, as a community with superior knowledge of same, present the issue for examination. I support taking a tack at this forum which seeks to discuss and tangibly understand whether or not lead-free is a fitting vector for these failures; as any such discussions can only serve to deepen our understanding of the phenomena as a whole. I believe that we all can benefit from any dialog which further elucidates this issue as it affects real-world products and systems. As others have rightly said, silence is what brought the world lead-free in the first place. Shall we continue here??? Just my 2 cents on a Friday morning -- ... --- Previous Message in This Thread --- Subject: Re:Expert recreates Toyota sudden acceleration From: Pete Houwen <[log in to unmask]> To: [log in to unmask], Marcus Thompson <[log in to unmask]> Date: Friday, February 26, 2010 7:04:22 AM > callling attention to unfounded "possibiilities" will be damaging to any attempts > to educate on the dangers of lead free solder. Crying wolf will only destroy > credibility. > > There is NO data, evidence, indications, etc. whatsoever that the Toyota > problems are in any way related to tin whiskers or lead free solder. All > implications of electronic failure are EMI and software related. Not even sure > why this is a topic of discussion on the LeadFree forum. > > Pete > > > ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ------------------------------------------------------------------------ -------Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Leadfree To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL) Search previous postings at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ------------------------------------------------------------------------ ------- ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ---------------------------------------------------------------------------- ---Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Leadfree To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL) Search previous postings at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ---------------------------------------------------------------------------- --- ---------------------------------------------------------------------------- ---Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Leadfree To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL) Search previous postings at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ---------------------------------------------------------------------------- ---   ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ---------------------------------------------------------------------------- ---Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Leadfree To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL) Search previous postings at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ---------------------------------------------------------------------------- --- -------------------------------------------------------------------------------Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Leadfree To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL) Search previous postings at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -------------------------------------------------------------------------------

ATOM RSS1 RSS2