Over the years a great deal of interest has focused on the art of etching patterns into surfaces of objects. Such patterns can be decorative, informative, can be for the purpose of providing nonskid surface properties, can be useful in forming copper printed wiring board patterns, and can be useful in many other applications where a specific pattern is desired.
Grit blasting has been effected in the past by employing a pattern mask prepared manually from rubber, paper, or various plastics and attaching the pattern mask to the article to be etched employing an adhesive. This method is time consuming and cannot be used to etch fine image details on a repetitive basis.
In the past, expensive metal templates have been held or attached to the surfaces and grit blasted at the templates to produce the etch. This method, since the templates must have small metal parts holding the template together, cannot produce fine detail. Additionally the metal template loses its shape with repeated use, and distorts the design.
The surface of the article can also be etched by silk screen printing an image in relief onto a very fine sticky backing paper. This method requires a very strong ink image. The sticky backing paper is dampened and adhered to the surface. The ink image is then grit blasted. The grit material must, however, penetrate through the paper and its adhesive before affecting the surface. During this time, the ink image must withstand the grit blasting. The resultant image is more of a frost than an etch, and is best suited for producing large numbers of etched items since the method is too costly for etching small numbers of items.
Die cut vinyl stencils are also produced as an etchant mask, and the time, effort and cost factors make the use of such stencils undesirable.
Several companies produce photoresist masks commercially in the United States. Each such mask has a commonalty in that an emulsion containing a photosensitizer and a reactive monomeric and/or polymeric substance is applied to a substrate which is then exposed, either dry or wet, to sufficient quantities of electromagnetic radiation of an appropriate wave length to activate polymerization or crosslinking catalysts, agents, initiators or mixtures thereof. The unexposed areas remain soluble to the action of solvents such as water, alcohols, hexane, benzene and when exposed to such solvents by the use of a washout device reveal the desired pattern or design. The exposed areas are rendered insoluble and form the mask. While the commercial productions can produce reasonable detail, some detail is destroyed during the washout. The method by which these masks are, by simple adhesive, transferred to the object to be etched, requires the masks to be burnished while applying. The failure rate for loss of pieces and fine detail which does not make the transfer, or is blown off the glass in the blasting is substantial.
One American company produces a laminated resist, produced much the same as the previous commercial mask, which has as an additional production step a thin film laminated to the polymerized resist. The transfer of this mask is better, but the production costs of this additional step make the mask very expensive. The loss of fine detail during washout is a problem.
Liquid photoresists are also commercially available which are painted or sprayed onto the surface of the object to be etched, and then exposed when dry to achieve a desired image. While the process does work, there are serious problems when working with any but a planer surface, and presents problems on water sensitive surfaces. The process is time consuming, expensive, and must be cleaned using special expensive removers.
Accordingly, a substantial need exists for a photoresist that is extremely easy to use, can readily develop an image or pattern, can be used on both water sensitive surfaces and surfaces having curves and contours. Such a photoresist, which can be produced quickly and inexpensively while providing extremely fine detail which transfers intact and adheres so fine detail is not blown off during the blasting is in demand, and is being successfully marketed by the inventor under the trademark of E-Z MASK.