Ryan,
        Sqeegee speeds range  from approx .5 inch/sec to 6inch/sec and
depend on printer, paste and sometimes production speed requirements.
However it seems that your real concern is the wiping after each print
which is an indication  of leakage of paste vehicle around the stencil
aperture allowing the vehicle on the bottomside of the stencil and
subsequent smears if not cleaned.
The factorinfluencing this effect is how stencil gaskets to the board and
you may need to look as points such as :   Board finish
        Board flatness
        Stencil condition fromthe point of  damage or rounded or soft
apertures allowing leakage
        stencil/board distance ie are you using off contact and how much?
        Sqeegee hardness? soft sqeegees can pump by their action- use metal
        Excess squeegee pressure  combined with the above can also contribute
Hope this is of use
Regards
Edward Hale


>Evenin' all!
>
>        My question is this:  My stencil printer operator has said that he
>has to
>wipe our 6-mil stencil each pass to get the paste in the 20-mill pitch
>aperatures for a QFP to release well.  We are using Amtech NC-559 type 3
>paste with 89.5% metal.  The paste is not old.  I considered using type 4
>paste, which has a much finer powder in it. I was told by Amtech that this
>finer powder paste will pack more densly into the aperatures and I could get
>some bridging, unless I order a new stencil with aperature reductions.  Our
>squeegee speed is 0.6 inches/s, or 15mm/s.  Is this too slow?  Amtech
>suggested that at this slow speed, the paste could be rising out of the
>aperature, as if someone pressed on a wet sponge and it rose back to its
>original shape.  What is a good squeegee speed for 20 mil pitch parts?
>Thanks all!
>
>Ryan Jennens
>TelGen Corp.
>
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