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Fire Safe Heating System for Combustible Solvents

IP.com Disclosure Number: IPCOM000051532D
Original Publication Date: 1981-Feb-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Ludden, RC: AUTHOR [+4]

Abstract

A coating process using a photosensitive film can be utilized for applying protective coating to the external surfaces of circuitized boards. The film is applied with a vacuum laminator to the entire panel surface, initially covering all external laminate surfaces, copper circuitry, and through holes. Following lamination, images are photo-exposed on the uncured film. Next, the board is passed through a solvent spray developer to remove unwanted coating from the proximity of copper surfaces that will be soldered in final assembly. Finally, the remaining coating material is cured in an oven to form a permanent solder mask and protective coating on the panel surfaces.

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Fire Safe Heating System for Combustible Solvents

A coating process using a photosensitive film can be utilized for applying protective coating to the external surfaces of circuitized boards. The film is applied with a vacuum laminator to the entire panel surface, initially covering all external laminate surfaces, copper circuitry, and through holes. Following lamination, images are photo-exposed on the uncured film. Next, the board is passed through a solvent spray developer to remove unwanted coating from the proximity of copper surfaces that will be soldered in final assembly. Finally, the remaining coating material is cured in an oven to form a permanent solder mask and protective coating on the panel surfaces.

An inherent problem in this process occurs during image development when the solvent spray process fails to dissolve all unexposed coating from the copper lands and thru holes. The developing process, briefly described, consists of solvent spray nozzles mounted horizontally on opposite sides of a rectangular tank. Images are developed on coated panel surfaces by traversing the panel in a vertical direction through the opposing sprays of solvent inside the tank. Butyl CARBITOL* is the particular solvent used for developing the film.

Developing with a low (ambient) solvent temperature contributes to incomplete development and therefore the removal of the unexposed coating. The chemical reaction necessary to remove/dissolve the unexposed coating is rapidly accelerated with higher solvent temper...