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November 2005

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Subject:
Re: [LF] Reliability prediction of LF soldering
From:
"Ingemar Hernefjord (KC/EMW)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Ingemar Hernefjord (KC/EMW)
Date:
Wed, 16 Nov 2005 17:41:30 -0000
Content-Type:
text/plain
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text/plain (47 lines) 
Werner,
The content of Lead in the resulting solder joint is very important for the endurance properties. Assume a)boards with a Pentium4, several superBGAs, QFPs, CCCs and a lot of other components (we make such mammut boards)where many components still have lead and we solder without lead b)vise versa. How do we know that the lead is distributed equally in all these thousands of joints? Universal have done a lot of testing, and they have found, that despite efforts, there is oftenly a great spread in the lead distribution, even after fully collapsed balls. Again, of what you have said, the distribution of lead is very important for the joint's endurance and relibility. If the lead distribution varies a lot, is it then possible to make MTBF predictions? This is very interesting point of view for us.

Inge

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Werner Engelmaier
Sent: den 16 november 2005 18:08
To: [log in to unmask]
Subject: Re: [TN] [LF] Reliability prediction of LF soldering


Vladimir,
I respectfully disagree--I have been at this for some 30 years--and I KNOW it
works. The reliability of the solder attachments can in fact be estimated
depending on the various physical parameters.

Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com


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