Is there an insulation compound for exposed leads on a PCB?
There are a wide range of compounds termed "conformal coatings" which provide varying degrees of insulation of the boards electrical conductors. Many of these can be applied by some or all of dipping, brushing or spraying. (A few are applied under very specialised vacuum conditions - not applicable here).
The main role of a conformal coating is protection of the PCBA from environmental factors, humidity, oxidation, corrosives, ...) with insulation being an important but secondary role.
You can get two pot epoxy coatings - which is a far more aggressive approach than you need.
A thin layer of a neutral cure silicone rubber will do a good job of insulation and isolation. Do not use acetic acid cure silicone rubber.
Wikipedia - conformal coating
Dow Corning - Conformal Coating Grand Masters [tm]
DC Conformal Coatings tutorial - 12 pages !
Ive used this DC CC - effective but environmentally nasty
DC - specific products technical notes
Humi seal conformal coatings training !!!
- A Conformal coating is a protective chemical coating or polymer film 25-75µm thick (50µm typical) that ‘conforms’ to the circuit board topology. Its purpose is to protect electronic circuits from harsh environments that may contain moisture and or chemical contaminants. By being electrically insulating, it maintains long-term surface insulation resistance (SIR) levels and thus ensures the operational integrity of the assembly. It also provides a barrier to air-borne contaminants from the operating environment, such as salt-spray, thus preventing corrosion.
MG chemicals CCs
Example - 422b silicne CC
- Ideal for high temperature environments. Silicone Conformal Coating (422B) is a flexible finish product that provides a protective coating for printed circuit boards against moisture, corrosion, and thermal shock. It protects and insulates electrical and electronic components and assemblies, including generators, motors, transformers, relays, and solenoid coils. For spraying, liquid can be thinned using M.G. Thinner Cleaner. Thin up to one half part thinner to one part coating.
Specific insulating coatings
Masterbond CCs
DIMAC CC video presentation
http://www.dowcorning.com/content/etronics/etronicscoat/