| 摘要 |
A two package UV curable conformal coating has been developed which possesses low moisture permeability and good electrical properties and provides a cure for shadowing of components on a printed wiring board. The conformal coating is a mixture of Component (A) which is a mixture of (1) from about 40 to 80% by weight, of a urethane having a free isocyanate group; (2) from about 20 to 60%, by weight, of reactive acrylate diluents; (3) from 0 to about 10% by weight of UV photoinitiators; and (4) from 0 to about 10% by weight of additives; and Component (B) which is a mixture of (1) about 50 to 80% by weight of an acrylate-epoxy resin; (2) about 1 to 10% by weight of an acrylate-urethane oligomer; (3) about 10 to 94% by weight of reactive acrylate monomers; (4) from 0 to about 10%, by weight, of UV photoinitiators; and (5) from 0 to about 10% by weight of additives; with the proviso that the total weight percentage of said photoinitiators and additives respectively each not be less than 1 percent and not exceed about 10 percent. Components A and B may be mixed in equal parts, by weight, or in a 1 to 2 part ratio, by weight.
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