Can anyone tell me where in the IPC standards there is information on the
height of Soldermasks & how this affects screening solderpaste onto the
board. The `rule of thumb' I'm working on is that the old Dry Film
SolderMasks were about 0.003" thick & were too thick for accurate
screening of solderpaste (paste would smudge underneath the screen because
of poor contact because of excessive height of soldermask over pad
height). Liquid Photoimageable SolderMasks were not a problem as their
height was roughly 0.001" (sometimes thinner) & didn't hold the
solderpaste screen too high for good `smudgeless' contact.

I'm interested in using some of the newer, thinner DFSM like Conformask.
One of our local PCB shops has this in 0.0024" & 0.0015" thickness. I'd
like to find IPC standards that can give direction as to whether these
thicknesses are usable or not.  I'm also interested in your findings as to
the suitability of these height soldermasks for paste screening.


--
Dom Bragge    (VK2YAK)      ___  _____  JNA Telecommunications Limited
Senior PWB Designer(R&D)__ / / |/ / _ | 16 Smith St  Chatswood  NSW 2067
Tel: (+61 2) 9935 5792 / // /    / __ | AUSTRALIA    [log in to unmask]
Fax: (+61 2) 9417 3862 \___/_/|_/_/ |_|    E-:-I   http://www.jna.com.au

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