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December 2001

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Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 18 Dec 2001 08:48:18 -0600
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Hi Lou! One test we have successfully used on past solder paste
qualifications is a long duration solder paste tack test. The process is
pretty simple. We selected a test assembly which had a wide range of
component types (both area array and SMT) and printed solder paste on 10 of
them. We immediately populated 2 boards but the other boards we populated
at 2 hour intervals. After population we insert a test assembly vertically
in a fixture which provided a "calibrated" hit on the bottom of the
assembly in an effort to see which components and how many fell off the
test assembly. It is a very informative method for comparing the tack
strength of different solder pastes over a 10 hour period and also
interesting on which types of components were more sensitive to solder
paste tack properties. This tack method gave us a good comparative index of
candidate solder paste tack and other properties such as bridging, slump,
etc. (we inspected the test assemblies before putting them in the tack
"tester"). Good Luck.

Dave Hillman
Rockwell Collins
[log in to unmask]




Lou Hart <[log in to unmask]>@ipc.org> on 12/17/2001 03:07:50 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>

Sent by:  TechNet <[log in to unmask]>


To:   [log in to unmask]
cc:

Subject:  [TN] Solder paste evaluation


TechNetters, our production people want to investigate an alternative to
the solder paste we are now using.  My proposal was to perform a designed
experiment to see if the candidate paste is better than, worse than, or
equivalent to the present paste.

Factors to consider in an experiment could, in my opinion, include the
pastes themselves, solderability preservative, lead finish, stencil life,
etc.

A big question than comes to my mind is:  what measurement do we use for
soldering performance?  Is there a variable measurement?  I'd rather not
use an attribute measurement, since that, as you know, requires a
relatively large sample size.  I don't like the prospect of using any
subjective measurement, fearing gage uncertainty will be excessive.

Any comments would be most welcome.  Contact me off-line for discussions if
this topic is too narrow for the forum.  Thanks to all.  Lou Hart

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