Technetters,

We are currently experiencing an issue with a black tar-like substance
accumulating in our solder pot. Samples of the substance were sent to the
manufacturer of the OA flux that we are using and they confirmed through
FTIR testing that it was thermally cycled flux. The buildup is seen on
machines using spray fluxers, but is much more prevalent on the machine
using a wave fluxer due to the added volume of flux being applied. We had
been using the flux for a little over four months with no issues, then the
substance started showing up even though there had been no process change
that we are aware of. At first I thought that it may have been a result of
some spilled Dew, but quickly ruled this out since I already know that Dew
burns off very quickly in the wave with no lasting residue.

The supplier claims that no changes have been made to their chemistry but I
am wondering if anyone else has seen this lately.

The substance accumulates in the machine around the chip nozzle, contour
nozzle, nitrogen diffuser rods, etc. resulting in the need for time
consuming 3-4 hour cleanings every two to three shifts.

Thanks in advance,
Dave

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