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Date: | Fri, 28 Dec 2007 10:59:43 -0600 |
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Greetings All,
I have a PTH TK type resistor component that is formed to fit an SMT
geometry land pattern. The component is Pb Free component plated using
Matte Tin over Nickel Flash. Once the component is soldered it exhibits non-
wetting/ poor wetting characteristics thus causing us to rework until we have
achieved acceptable results. Of course this is not what I would like to see
occur, but unfortunately at this time it is the process. The installation process
is as follows:
- Part is formed using a lead forming tool
- Is tinned using 25% RMA for 3 seconds and let to dry (somewhat); then
soldered (SnPb tin/ lead alloy) for 3-4 seconds in a 600F bath
- It is soldered (SnPb tin/ lead alloy) to the cca using a 6ooF solder iron tip for
2-3 seconds
- END…
Apparently this has been an issue for years, but just recently was brought up
to our Engineering department. We tin the component to allow for improved
wetting characteristics, but this does not provide much improvement. I have
done some investigation on the internet looking for reports and tests
performed soldering Matte Tin over Nickel using standard Tin/ Lead alloy, but
have found very little information regarding this. The component manufacture
states our process as described to them 'should work without issue, but this is
not the case.
So my questions are what are the issues related to soldering matte tin over
nickel flash with tin/ lead alloy? What hand soldering parameters are
considered optimal/ ideal with a low-mass matte tin plated component
considering the information provided? Is it possible to get very similar results
using this combination of metallurgies versus using tin/ lead plating and solder
materials?
Any help would be appreciated.
Thank You,
Chris
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