Hey Joe,

I am a supplier of both HASL solder and flux. I would like to point out the
following potential issues that can affect the appearance of your solder
finish.

1. Solder Thickness. The solder deposit must have adequate thickness or the
intermetallic will make it appear dull. This can be adjusted by the speed at
which the board passes through the air knife, air knife angle, and air
pressure.

2. Solder contamination. I believe you said you had you had your solder
checked for metallic impurities but solder mask residues ( uncured LPSM )
could also give you dull solder.

3. I really doubt if using a thick flux would have anything to do with dull
solder but you might try thining your flux with water ( 15% ) and then seeing
if that has any affect,

4. I believe you said the solder had a hazel appearaance. This might mean you
aren't getting proper rinsing. The post processing of HASL panels through
deep gold and subsequent resist stripping will also change the appearaance of
the HASL deposit.

These are just a few things to try. I hope they help.

My Best,
Chris McGary
Dexter Electronic Materials

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