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US 4,064,290 AGranted
System for coating plated through hole surfaces
OwnerJulius Alex Ebel, Ernest H. Mitchellinventors
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Abstract
A system is disclosed for coating the interior surfaces of plated through holes in printed circuit boards by flowing a minimal volume of a low viscosity fluid carrying resist solids through holes in a board. After coating, the liquid phase of the fluid is evaporated, leaving a protective solid coating adhered to the walls of the plated through holes. The system enables positive imaging of the printed circuit boards preparatory to etching.
Claims6
A method of coating the walls of holes through a printed circuit board to provide a resist coating on such walls comprising the steps of:
- providing a fluid having a characteristic for adhering to said walls and curable to a solid coating;
- flowing a stream of said fluid through said holes, which stream completely fills said holes and whereby flow is in sufficient quantity to purge air and impurity particles from said holes;
- and
- ceasing said stream of said fluid and curing such fluid as adheres to said walls to provide a coating.
1 more element
Dependencies are inferred from the claim text.