Improving etch resistance of a casein-based photoresist
AssigneeRCA Corporation
InventorDonald C. McCarthy
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Abstract
The etch resistance of a casein-based photoresist pattern to low specific gravity ferric chloride based etchant solutions is increased by treating the photoresist pattern with a formaldehyde solution containing at least 10 percent formaldehyde by volume by a period of at least 30 seconds, and thereafter drying the photoresist pattern.
Claims15
A method of improving the etch resistance of a casein-based photoresist pattern to a low specific gravity ferric chloride based etchant solution comprising, treating a dried casein-based photoresist pattern with a formaldehyde solution, and thereafter drying the treated photoresist pattern.
In a method of producing a photoresist pattern of improved etch resistance on a circuit board, including the steps of:
- (a) applying a casein-based photoresist solution to a circuit board to form a photoresist film;
- (b) drying said photoresist film on said circuit board to form a photoresist;
- (c) exposing said dried photoresist film to actinic radiation through a photomask;
- (d) developing said exposed photoresist film to thereby leave a pattern of photoresist film on said circuit board;
- the improvement comprising the additional steps of,
- (e) treating said phtotoresist pattern with a formaldehyde solution to improve its etch resistance;
- and
- (f) thereafter drying said circuit board.
Dependencies are inferred from the claim text.