conformal coating for harsh enviroment 1

[antonino]

hi
could please suggest the best coating material (acrylic, urethane or others)for a printed circuit board, in fact a battery charger controller board, in a refinery app. which is known for the content of H2S, SO2 and NH3.
thanks and rgds

 

[itsmoked]

The vendors will tell you which product will protect from what.

Urethanes are the nicest these days if you can use them. THE 'conformal coatings company' is Humiseal. They also seem to have good prices.

http://www.humiseal.com/

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ScottyUK]

Electrolube have a silicone based conformal coating called SCC which was very good for chemical resistance. It was an absolute nightmare for rework because it had good adhesion and most solvents didn't touch it. High temperature rating too. Methylene chloride loosens it, but that is savage stuff which you don't want to be playing with unless desperate. Their applications table is a good summary of the technologies, regardless of the supplier:

http://www.electrolube.com/docs/charts/conformalcoatings.pdf

The other company I had in mind was Concoat who I see have been merged into Chase Humiseal in the intervening years.

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Sometimes I only open my mouth to swap feet...

 

[cambria]

Go with a parylene coating. It is a dimer that is sputtered on the board in a vacuum. After that your board will operate underwater. It will operate under acid for that matter. The coating will not peel, as it is deposited on molecule by molecule, and is very tough. It is expensive, but I use it as our standard coating, and it will not fail you.

doug

 

[itsmoked]

cambria; That's interesting. What's it cost, approximately, for say 10 boards - 5" X 5"?

I take it repairs = throw it away?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[antonino]

One vendor said acrylic would be great and another one suggested urethane or silicone.
I am asking now for test or references from them.
rgds

 

[antonino]

Hi
This is what one supplier told me
"We have contacted the manufacturer of the resin (urethane)used in the ( spray can P/N ). Unfortunately, they have no testing data for compatibility of the cured resin with the 3 corrosive gases we discussed: hydrogen sulfide, sulfur dioxide, and ammonia gas. They have plenty of solvent data, but none on the gaseous environments."

I have seen advertising from protection relays manufacturers saying that their products are protected for such gases.
Anybode can help again?
rgds