Mike

Your assumptions regarding the source of your increased contamination levels
are correct.  The porosity, thickness, and cure of the mask has a direct
relationship to its ability to be cleaned thoroughly.  The cleaning system
configuration also has a role to play as to whether you are have a
saponifier, heated DI water, and settings of the nozzle pressures.  You are
also correct in that matte type masks help to reduce solder balls.

In any process or material change exercise it is a good idea to baseline your
current performance, then use this data to evaluate the effectiveness of the
changes implemented.  I would suggest that you test the ionic cleanliness
levels of your existing mask finish relative to the levels of contamination
and effectiveness of your cleaning system.  Then repeat the experiment for
the mask candidates you are evaluating.  There are several very good matte
type masks on the market, so you should be able to find something to meet
your needs.  The investigation into which mask to select requires a Design Of
Experiments to downselect to the best performer for your application.

Contact me offline if you require further assistance.

Regards,

Pat Kane
Contamination Studies Laboratories
765-457-8095

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