Tony,
I know the problem you describe.
A couple of years ago I worked on a project developing a screen cleaner
using moving bar spray. It did a good job on stencils using SC200  but
always failed to remove completely solder particles from mis-printed boards.
Even with all the flux removed the solder particles insisted on staying in
the interstices formed by the solder resist. My discussions with the
chemists at Dr Wack Chemie, in Germany led me to believe that the problem
was associated with the surface free energy/tension of the materials
involved. Their chemists were working on an additive to help this problem
but I left that particular employment before any result.
Your local distributor of Vigon should be able to follow this up.
Alternatively, a high pressure spray directed to the problem areas seemed to
do the trick but this would need to be manually operated or the equipment
could be very expensive.
Hope this helps
Regards
Eric Dawson

> -----Original Message-----
> From: Tony Conlon [SMTP:[log in to unmask]]
> Sent: 06 July 2001 8:44
> To:   [log in to unmask]
> Subject:      [TN] Cleaning of Mis-printed boards ...
>
> Morning folks,
>                             Here's a brief summary of the situation:
> Boards
> exiting the screen printer and found to be mis-printed ... we are manually
> cleaning at the moment (AlphaMetals Screenwash & Lint-free cloths) ... it
> works but not consistant ... thus auditors etc ... would not be
> particulary
> impressed. Due to certain issues we have decided that we cannot clean
> boards for a particular customer ... they have to be scrapped. Big
> problem!
>
> In the past we have tried the old 'Kerry stencil cleaner' (operates by
> means of a rotating arm dispensing the cleaner approx 20min cycle) as a
> board cleaner ... with Vigon SC200 solution: The result ... ok ... but we
> have gold contact-fingers to contend with and the paste seems to lodge at
> the fingers edge and the rest ...
> We also tried the newer 'Kerry' machine (Ultra-sonic based) ... not
> successful either I'm afraid.
>
> We have also tried a Branson Ultrasonic cleaner (with Vigon & Clean-thru)
> approx 30min cycle ... same story as above.
>
> Right guys! Any super-duper cleaning equipment/solution spring to mind?
> The
> gold contact-fingers are really making life difficult.
>
> Cheers guys,
>
> Tony.
>
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