Mike

Glossy or matte bear no specific relation to ionic contamination, per se. It is
probable that the chemistry and/or curing of the different masks play a far more
important role. Try ionic testing of both types of bare board to find out whether the
cause is the mask itself or the post-soldering residues. Which flux are you using and
what is your cleaning process? Some water-solubles will react with some substrates,
rendering them more porous. Whereas it is true that a glossy finish has a much smaller
surface area than a matte one and may therefore be less likely to become absorbant, the
difference is insufficient to be really significant with good masks of either type.
Many users of matte masks subject them to far worse electrical conditions than you
outline, very successfully.

Brian

Michael Forrester wrote:

> We recently changed some of our PWB's soldermask from a glossy to matte finish.
> Since then, we have had problems with contamination
> on the surface of the PWB's due to poor cleaning.  To fix the problem the finish
> was changed back to a glossy.  There is an effort to change all
> of our boards to a glossy soldermask.  I believe it is not an issue of matte vs
> glossy but rather the porosity of the specific soldermask being used.
> Our boards are high density surfacemount with frequencies above 1 GHz running
> through the circuitry.  I prefer the matte finish for ease of inspection
> and reduction in solder balling.  We use an OA flux in manufacturing the PCA.
> Can someone give me the Pros and Cons of matte and Glossy soldermasks?
> Also, am I correct in stating that whether the finish is matte or glossy has
> nothing to do with whether or not we will have ionic contamination after
> cleaning?
> Thank you.
>
> Best Regards,
>
> Mike
>
> ##############################################################
> TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
> ##############################################################
> To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
> the body:
> To subscribe:   SUBSCRIBE TECHNET <your full name>
> To unsubscribe:   SIGNOFF TECHNET
> ##############################################################
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
> information.
> If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
> 847-509-9700 ext.5365
> ##############################################################

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################