Looking for a conformal coating

Maker, DIY
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Hello. I need a conformal coating for a populated copper protoboard or PCBs to prevent oxidation and corrosion. I don’t know if silicone, urethane, poylurethane, acrylic or epoxy would be most appropriate and unfortunately that sort of data I’m finding difficult to find. Spray-on would be easiest, but paint-on would do. I’m also looking for a green UV curable maskable solder resist for unpopulated PCBs that people have had good success with (film or liquid). Thanks.

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Welcome to the forum.

Conformal coating choice is dependent on the specific end product requirements. For the simplest cases an inexpensive acrylic spray costing pennies per PCB is sufficient (e.g. product is in a protective housing in a garage). For extreme environments it may require a silicone dip costing dollars per PCB.

Here’s a few of the end product operating specs that need to be considered in choosing the material choice:

  • Ambient temperature range
  • Does it need protection from submersion, direct water spray, or just ambient humidity
  • PCB raw or in an enclosure
  • Abrasion resistance
  • Serviceability

When cost is a major consideration and high reliability is required, the selection often requires extensive study of the operating environment and then qualification testing of the final choice.

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Thanks, Paul. My needs are modest (indoor, enclosed, dry environments). Any specific products at Digikey that you’d recommend?

Any experience with the obligative green PCB solder resist masks? I’ve heard some complain of problems with delamination.

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Below are some
Conformal coating options

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I’ve never used a DIY solder mask, so can’t help there. Last century when I still occasionally made a DIY PCB I’d skip the mask since I was hand soldering one offs or prototypes.

For an indoor, enclosed, dry environment I’d generally not use any conformal coating. (I’ve never seen a conformal coating used on an consumer product PCB for that environment).

Second choice would be just a clear acrylic spray paint instead of an expensive conformal coating. (Krylon Crystal Clear $5.00 US at the hardware store)

If I had to use an actual purpose made conformal coating I’d buy the cheapest product that is in a spray can (all the Digi-Key options are very good). For material type it depends on if the PCB needs to be easily serviced. If you won’t need to service/rework the PCB’s after coating, any type will do. If easy service/rework is a requirement then I’d choose an acrylic based coating.

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