Werner, we ran the same experiments at Square D around 1983, 84 time
frame and got the same results. The leader of the project tried to
publish on it, but the exec management at the time felt it would give
away a competitive advantage.
Bob
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Friday, September 04, 2009 10:12 AM
To: [log in to unmask]
Subject: Re: [TN] BGA/LGA land shape versus assembly yield reliability
Hi Joe,
In the '80's, we at Bell Labs tries round, and rectangular pads. The ATC
results showd a slight reliability advantage for solder joints resulting
from rectangular pads. I have a paper in SMI sometimes in the early
'90's [Bell Labs management would not let it be published at the time]
with the data. The reason for the rectangular pads , by the way, was
smaller possible pitch.
Werner
-----Original Message-----
From: Joe Fjelstad <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, Sep 3, 2009 8:10 pm
Subject: [TN] BGA/LGA land shape versus assembly yield reliability
Greetings folks.
I did a quick check of the archives on the subject and drilled a dry
well (maybe drilled in the wrong place?).
That said, in design and lay out we all tend to match pad shapes on the
board with their mates on the package (round hole - round peg , square
hole - square peg)
My question is has anyone looked at (or know of) round with square and
vice versa and collected assembly efficacy/results and/or reliability
data?
Finite Element Modeling data would be of interest as well.
Thanks in advance for any responses
Joe
Since its Friday in some place of the world (or soon will be) I was
looking over the period table recently and afterwards was wondering if
anyone had ever mentioned that this little forum has it very own
element, TechNetium, the first man made element. (the upper case N is
my suggestion for future spelling... ;-)
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