Are there any defense contractors out there who have any customer (DoD,
Army, Navy, etc.) contacts (names, phone numbers, email addresses or
websites) working to find cost reduction opportunities with their
electronics suppliers / contractors. I am looking to find government
organizations who win when they utilize suppliers who practice lean
manufacturing, best practices and the like. For me, I am seeking customers
who can help reduce the barriers (ex. Mil specs for non-value added
requirements).
thanks,
Mike Weekes
[log in to unmask]
-----Original Message-----
From: Werner Engelmaier [mailto:[log in to unmask]]
Sent: Tuesday, December 10, 2002 9:02 AM
To: [log in to unmask]
Subject: Re: [TN] BGA standoff distance
Hi Joe,
You ask: "Is standoff distance considered a good indicator of correct solder
ball
collapse? Is there a formula for calculating what the theoretical standoff
distance should be after reflow based on package weight, solder ball
diameter, # of balls, etc...?"
Standoff height is the major geometric parameter besides component size
determining solder joint reliability. Observed height variations are
indicative of BGA warpage during reflow soldering. BGA warpage during reflow
is a fuction of unequal heating and thermally asymmetric design. If the
corner solder joints are the ones with the shorter standoff height
reliability is reduced.
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com
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