KPR, originally known as
Kodak Photoresist, is a
photosensitive material used in
photoengraving,
Photogravure and
photolithography
In integrated circuit manufacturing, photolithography or optical lithography is a general term used for techniques that use light to produce minutely patterned thin films of suitable materials over a substrate, such as a silicon wafer, to protect ...
. Once dried, KPR can be dissolved by several solvents. However, after exposure to strong
ultraviolet light, it hardens and becomes insoluble by some of these solvents. It is also resistant to
acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
,
ferric chloride and other chemicals used to etch metals.
The fundamental method of its use was first described in two US Patents, USP 2610120 and USP 2670287,
assigned to the
Eastman Kodak Company
The Eastman Kodak Company (referred to simply as Kodak ) is an American public company that produces various products related to its historic basis in analogue photography. The company is headquartered in Rochester, New York, and is incorpor ...
of
Rochester, New York. These photo-resistant resins are formed from cinnamic acid esters, with the most preferable being polyvinyl cinnamate. While they were developed primarily for photolithography for high-speed print setting for uses such as newspaper printing, their perhaps highest value came from their ability to produce non-conducting layers on top of conducting layers to precise dimensions. This enabled the "printing" of large scale, closely placed conductive and non-conductive pathways to create binary gates. These were semi-conductors or the means to create semiconductors. This technology was utilized heavily by the Shockley 8, at the original Fairchild Semiconductor to produce more and more closely spaced semiconductors for computing. It is ironic that Kodak, the original patent assignee, did not really participate in the economic juggernaut that it created through this lithographic printing technology.
References
Kodak
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