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From:
"Wenger, George M. [Contractor]" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wenger, George M. [Contractor]
Date:
Wed, 12 Mar 2014 19:55:31 -0500
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text/plain (58 lines)
Steve,

I responded to Todd's TN post off-line but then realized that there might be others at TN who might want to see what I sent Todd.  I've attached a PDF file with the info in case you'll be able to put it up on your site.

Regards,
George
George M. Wenger
Failure Signature & Characterization Lab LLC
609 Cokesbury Road, High Bridge, NJ 08829
(908) 638-8771 Home  (732) 309-8964 Mobile
E-mail [log in to unmask]
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-----Original Message-----
From: Wenger, George M. [Contractor] 
Sent: Wednesday, March 12, 2014 1:01 PM
To: 'MacFadden, Todd'
Subject: RE: Solder Joint Interconnect Pull Strength Tests - Standards?

Hi Todd,

I'm not sure that this is what you are looking for.  There really isn't any recognized industrial pull strength specifications.  The attached shows what we did many years ago when we first started seeing what we called "Double Reflow" defects.  At that time we found that typical 50 mil pitch gull wing lead solder joints had a pull strength of approximately 1Kg force (2.2 lbms) when pulled at room temperature and the pull strength decreased linearly with temperature.  When we did pull strength testing we were much more interested in the mode of failure rather than the strength.  We always wanted to see cohesive failures in the solder and not adhesive failures at an interface.  I hope you get some usefull information from the attached. 

Regards,
George
George M. Wenger
Failure Signature & Characterization Lab LLC
609 Cokesbury Road, High Bridge, NJ 08829
(908) 638-8771 Home  (732) 309-8964 Mobile E-mail [log in to unmask] [log in to unmask]


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of MacFadden, Todd
Sent: Wednesday, March 12, 2014 12:04 PM
To: [log in to unmask]
Subject: [TN] Solder Joint Interconnect Pull Strength Tests - Standards?

Is anyone aware of standards for conducting and evaluating lead pull tests, and are there typical expected lead pull (or push) values for the common interconnects (i.e., gull wing, castellation, BGA, chip cap terminals, etc).

Perhaps there are too many variables -- e.g., type, finish, configuration and size of the lead; solder type, etc. -- to establish standard pull strength values. We've always just used relative comparison of values from sample lots against controls, but I'm wondering if there are typical expected pull strength values from industry we can reference.

I noted from MIL-STD-1580B: 10.1.1.2 Terminal strength. Perform a lead pull strength test on all parts (two parts minimum) in accordance with the applicable specification. But what is the "applicable specification" being referred to here?


Thanks in advance!
Todd MacFadden


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