Hi Rama,

I have a question to ask, do you see the paste sticking to the blades all the
time, or does it seem to happen at the beginning of a run?

The reason that I ask, is because I experienced this problem in the past with
a paste I was using from AMT. The paste needed to be "shear-thinned", or
worked, for it to perform it's best.

For example, we would see the same thing you see on the first print of a run,
or after lunch-break when the line sat idle for a while. The first print, if
the paste wasn't "worked", wouldn't show the roll of the bead of paste in
front of the squeegee that you normally want to see. When we asked about this
problem with AMT, they did say that the reaology does change when the paste
is more-or-less in constant motion, from what it is when sitting still for a
while.

If I remember correctly, some printers have a function in their programs
where you can set them to "work" the paste before the print stroke...for the
life of me, I can't remember exactly what they call that function...I must be
going senile...hehehe

Could it be that the same thing is happening with your new Kester paste?

-Steve Gregory-

> For more than 4 years, we were using Alpha metals, no clean 63/37 paste.
> Recently we tried the Kester paste on our DEK printers. The printing
> performance is far better than the Alpha Paste. So, we switched to Kester
> FL250D no clean paste (63/37, 90%, Mesh -325+500 , VISC 1400-1800 ).
>
> But, we are having serious unexpected problem on MPM printers. The paste
> does not drop from the blades after the print stroke causing big voids on
> the boards. We are scrapping quite a few boards due the misprints.
>
>  Is there any solution for this problem ? Some one suggested 'TEFLON'
> coated squeegee blades.
>
> Sincerely,
>
>  Rama Vemulapalli
>
>

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