Cleaning assembled circuit boards?

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I am experiencing sporatic de-wettting issues, so I have bee... - May 19, 2010 by John

In general, cleaning with deionized water is acceptable for ... - May 20, 2010 by robgd3

A lot of our dewetting is happening on plastic body componen... - May 20, 2010 by John

First, what's wrong with some dewetting of conformal coating... - May 20, 2010 by davef

John

#61873

Cleaning assembled circuit boards? | 19 May, 2010

I am experiencing sporatic de-wettting issues, so I have been thinking about ways to clean fully assembled circuit boards that have open switches, contacts, etc. I also suspect that that plastic bodied components have residual silicone mold release from the manufacturer. Does anyone know of a system to effectively clean assembled circuit boards that doesn't have any adverse affects on the components? Any help would be greatly appreciated.

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robgd3

#61877

Cleaning assembled circuit boards? | 20 May, 2010

In general, cleaning with deionized water is acceptable for most component. Open switches and contacts, in general, do not get damaged in this process. A good drying is required, of course, after washing.

However, you've described dewetting issues. We read dewetting as a solder joint issue, where the solder does not properly wet to the pad of the board, or to the component leads. If this is what you're experiencing, wash processes on fully populated boards won't help you much. Unless there's another detail that we're missing.

cheers ..rob

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John

#61879

Cleaning assembled circuit boards? | 20 May, 2010

A lot of our dewetting is happening on plastic body components, such as ICs. When they are manufactured, the molding process requires a mold release to make the part release after molding. Usually, the release agent is silicon based, but you can't see it or feel it. Coating will not stick to this.

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davef

#61885

Cleaning assembled circuit boards? | 20 May, 2010

First, what's wrong with some dewetting of conformal coating on component bodies?

Second, there are chemistries that might be able to remove silicone mold release, but cleaning the chemistry is not easy without affecting the whole board, as you imply in your question.

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