Hi Bev,
Dewey makes the point with tongue squarely in cheek.
Indeed, if you can add more underfill you have an 'under filled' situation.
The whole point of an underfill is to create a connection between component and PCB other than the solder joints. That is why underfill should be specified in terms of both modulus of elasticity and CTE [see my reliability column attached—sorry, for the rest of you it is Engelmaier, W., “ReliabilityImprovement with Underfill,” Global SMT & Packaging, Vol. 6,No. 3, March 2006, pp. 66-67.]
Werner
Upcoming workshops:
September 21, European Electronics AssemblyReliability Summit, Tallinn, Estonia,
“Solder Joint Reliability-Part 1: Fundamentals in SolderJoint Reliability”
September 21, European Electronics AssemblyReliability Summit, Tallinn, Estonia,
“Solder Joint Reliability-Part 2: Failure Mode and RootCause Analyses (Fatigue, Brittle Fracture, ENIG)”
November 2 & 9, SMTA Webtorial,
“Fundamentals in Solder Joint Reliability”
December 7 & 14, SMTA Webtorial,
“Acceleration Models,Accelerated Reliability Tests and Screening Procedures”
-----Original Message-----
From: Bev Christian <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, 23 Aug 2010 11:19
Subject: [TN] Double underfill
Technetters,
I would like your opinions on a theoretical underfill situation. What would be
your comments be if a process group told you that they had underfilled a
component and it was cured and they wanted to add more underfill to the
component?
Bev
RIM
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