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Applying TacFlux to a Solder Thermal Interface Material
Posted by Amanda M. Hartnett
Friday, September 5th, 2008
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The process of applying a solder thermal interface material typically
includes applying flux to a solder preform and reflowing it in a sandwich
between two substrates. When a preform
comes flux coated, it’s a no-brainer how to apply the flux to the preform. It’s
already done for you.
There are so many great types of flux available for specific
applications, that you might want to use a specialty flux formulation matched
to the substrates you are soldering to and the reflow temperatures you will be
running. This flux formulation is
commonly a Tacflux and the key to good flux application is not to overdo it. A little bit goes a long way.
This past week I ran a soldering experiment in which I
was soldering a 1” preform of 121 alloy (96.5Sn3.5Ag) to copper and wanted to
use TacFlux 023 because it is specifically formulated for soldering lead free
solders to standard soldering metallizations such as copper. I knew that in the soldering process, the
flux needed to make contact with the entire substrate I was soldering to, but I
didn’t know how far out the flux would wet or how much flux I should apply. I ran a few trials to test out various dispensing
methods and amounts. What I found in the
end was that one dot of flux dispensed onto the center of the substrate was all
that was needed to remove the surface oxides and wet the solder over the entire
1” surface
