Kathie

It is probably overkill and you probably actually degrade the boards by
a pre-assembly clean (oxidation of the surface finish). The crux is are
they sufficiently clean at the end of the line? Vapour degreasing is a
poor cleaning method, as has been shown zillions of times. What solvent
are you using?

I do not recommend dishwasher type machines which probably do more harm
than good. They are poor in performance, gobble up energy and clean
water and dry very poorly (some can even overheat the boards). There are
alternatives that cost twice as much but consume 1/4 the volume of water
and 1/3 the electricity, and actually clean and dry extremely well
(including after assembly).

Brian

"Lambert, Katherine A." wrote:
>
> Hi folks,
>
> In our operation, we currently clean all bare boards before running them
> through the assembly process.  After automated assembly (using RMA based
> solder paste), the boards are cleaned again in our in-line cleaner or vapor
> degreaser.  The bare boards are also cleaned in either the in-line cleaner
> or vapor degreaser, both of which are probably over kill.  These boards go
> into military radar systems.
>
> My questions are:
> 1.      Most of our boards come in visually clean.  Occasionally, we get
> some boards that look oxidized.  What is the risk of not cleaning?
> 2.      We're considering a small batch cleaner - something on the order of
> a Maytag dishwasher with dishwashing detergent.  I've seen this used in some
> small commercial operations.  How wide spread is this practice and does it
> make sense?
>
> Kathie Lambert
> Process Engineer
> Northrop Grumman
> Baltimore, MD
> 410-765-9746
>
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