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March 1998

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From:
TheITMTeam <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 10 Mar 1998 17:16:56 EST
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Ruben -
I believe it may be time (overdue, in fact) for a solder paste evaluation.
Nothing against the Qualitek formulation but you may find a solder paste that
behaves a lot better in all regards in your process and in your environment.

My company performs a lot of solder paste evaluations and one of the things we
look for is residue level - thickness and clarity.  Some fluxes are
susceptible to what you have when there is a high peak temp.  You may or may
not be able to avoid this, depending upon the thermal ability of your oven and
the complexity (particularly mass and surface geometry) of your application.
Suffice it to say that there is a big difference among the pastes we've tested
of late - particularly the very low- and ultra low- residue formulations that
don't, by the way, require inert atmosphere.

I strongly recommend that you undertake a thorough solder paste evaluation
program, using your current formulation as a benchmark.  Besides residue
levels, test for wetting angle, printability, solder balls, work life and tact
time as a minimum.

When was the last time you qualified your solder paste, anyway?

Phil Zarrow
ITM, Inc.
Durham, NH
[log in to unmask]

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