moisture seal

[homemade24]

I have some small homemade circuit boards that I built that are somewhat exposed to the outside environment
I looking for I guess some kind of spray moisture sealant to protect them
about all I have found is the red insulating varnish use in motors and transformers.
I have seen boards with a somewhat clear sealer on them.
can this be bought in a spray can in the US
thanks

 

[crutschow]

It's called a Conformal Coat for printed wiring boards. It's sold by many conpanies, see **broken link removed** for example.

 

[homemade24]

thanks crutschow
that's just what I was looking for.
I've got to order some stuff from Digi-key I did a search on there site but nothing cam up . do you or anyone know if they sale something like this under a different name or brand
thanks again

 

[Boncuk]

Check out Kontaktchemie in Denmark.

 

[Menticol]

I think a well sealed container and silica gel granules inside should work better

correct me if I'm wrong, but that mentioned sealants make maintenance more difficult, right?

 

[crutschow]

I didn't find any at Digikey either but did find some at Coatings | Newark.com, but they're not cheap.

You might also consider just using some outdoor urethane wood finish spray such as **broken link removed**, which should provide good protection, and that should be available at any paint store.

 

[homemade24]

I think a well sealed container and silica gel granules inside should work better

I do use silica gel and the container is is some what water proof but after a few years the solder joints start corroding
crutschow
I was wondering if just a good poly spray would be ok.
if you think that will work OK that's what I will try

 

[jpanhalt]

The conformal coating I have is basically a clear, acrylic lacquer. The big box stores carry acrylic lacquers in spray cans. A polyurethane would probably work too, but not dry as quickly.

John

 

[crutschow]

I was wondering if just a good poly spray would be ok.
if you think that will work  OK that's what I will try[/QUOTE]Isn't poly short for poly-urethane, which should be the same as the urethane spray I mentioned?  I believe that would work ok.

 

[homemade24]

I will give it a try and let you know in about 2 to 3 years if indeed it works LOL
thanks guys _ headed to wally world to pick up a can

 

[jpanhalt]

One thing to remember is that acrylic lacquers dry by solvent evaporation. If you ever need to make repairs, you can usually solder right through them or if not, use lacquer thinner, acetone, or MEK to remove them in a small area. Some brands to look at are Plasticote, Krylon, and Tempo. Rust-Oleum makes both a clear lacquer and a clear enamel paint. So be sure to read the label.

Polyurethanes cure by a chemical reaction, and you may not be able to solder through them. You must use very aggressive solvents (e.g., paint stripper) or scrapping to remove them. Anything with the word "paint" in it (e.g., alkyl or acrylic enamel paints) will have similar properties to polyurethanes.

John

 

[homemade24]

thanks jpanhalt
I guess acrylic lacquer would be the best for me
and I think I may look at getting some to bush_on instead of spray because I do have a pot for calibration and a Pic chip that I remove for programming changes
any opinion on that is welcome

 

[jpanhalt]

I would spray without a second thought. If you are worried about the pot, put a little circle of masking tape on it over the screw adjust. I have never had a problem, though. I would not worry about the PIC. Remember to spray multiple thin(ish) coats rather than one very heavy one. I usually get by with one, just wet coat.

You will find it much easier to get acrylic lacquer in a spray than in a can. For the can, you may need to go to an auto paint place, and it will be very expensive.

Of course, the polyurethanes are in both can and spray.

John

 

[homemade24]

sounds like a plan
thanks