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Date: | Wed, 11 May 2005 10:56:04 EDT |
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The "matte" or "gloss" in a solder mask is set by the mask formulator. In
that regard, it is the same as paint. The matte agent is usually an inert
filler, like silica. Gloss is a function of light scattering by the surface.
Normally, all masks are relatively transparent, so that you can see the
outline of the circuitry below the mask. On the other hand, nomenclature inks tend
to be opaque, so that they have good contrast to the mask.
I don't recall that the IPC has ever tried to quantify "gloss" in any of the
revisions of SM-840. If you want to try that, I suggest you fall back on
the paint industry standards, but I would guess that your board supplier will
not have the equipment to measure gloss.
Jeffrey Bush has gone through the major technical considerations in choosing
gloss versus matte - ease in cleaning, conformal coat adhesion, nomenclature
adhesion, ease of inspection, and solder ball formation. The TechNet
archives may be helpful, as this topic was widely discussed 3-5 years ago.
I would suggest you list the qualities you want in your mask surface, and
work through your supply chain to specify the mask and vendor you want.
Denny Fritz
MacDermid, Inc.
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