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:
Sep. 09, 1986
Filed:
Mar. 19, 1985
Donald F Sullivan, King of Prussia, PA (US);
Other;
Abstract
A process is described for improving the quality of images which have been formed by screen printing a liquid photo curable photopolymer. Images formed by screen printing, especially heavy coatings such as solder masks on printed wiring boards, inherently have indistinct boundaries, and may have feathered edges and photopolymer smears. These indistinct boundaries are removed and the resolution improved by a process which utilizes the oxygen inhibition effect characteristic of selected photopolymers. Thus, a screen printed image can be 0.001 inches thick at the center of a line, tapering off to 0.0001 inch thick smears, and these smears may be eliminated by irradiating the entire image with a moderate amount light energy, which cures the thick image portion and leaves a liquid boundary layer on the order of 0.0001 inch thick due to the oxygen effect. When washed with a mild solvent the liquid layer is removed, including the smears, leaving the thick image portion undisturbed. In a preferred embodiment a phototransparency is interposed over and out of contact with the images and then irradiated with non-collimated UV light so as to harden the thicker image sections while indistinct boundary areas are shielded by opaque phototransparency areas. Light undercutting due to the use of non-collimated light does not polymerize the smears because of the oxygen-inhibition effect and the thinness of the smears, and thus only the undersirable smears will be inhibited and left in the liquid state for removal to improve the resolution.