The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 20, 1990
Filed:
Jul. 26, 1989
Donald F Sullivan, Paradise, PA (US);
Other;
Abstract
A photopolymer layer is used as a radiation transparent phototool replacing a light blocking phototool in the photographic process of producing solder mask layers on printed wiring boards. Various simplification and energy reducing steps are introduced with off-contact photoprinting of patterns on liquid photopolymers having special characteristics that permit the polymerization of patterned outer skin areas partly through the thickness thereof with a controlled amount of radiation energy. This creates an in-situ surrogate phototool that permits further polymerization throughout the thickness of the layer with controlled quantities of unpatterned radiation energy. Photodiscrimination is provided by changes of photosensitivity in the layer transparent to radiation rather than by opaque imaging. Thus a first low energy photoflash through an off-contact phototool with uncollimated radiation creates on a liquid photopolymer surface two contrasting patterned areas of liquid polymer and polymerized skin. This can be achieved in an inert gas atmosphere. The second curing step in the presence of an inhibiting gas such as air with controlled radiation energy then fully cures through the thickness of the layer those skin covered portions without curing the liquid surfaced areas.