HABIs in DuPont Photopolymer Films for the Electronics Industry

HABIS IN DUPONT PHOTOPOLYMER FILMS FOR THE ELECTRONICS INDUSTRY 

Non-silver photosensitive materials had long been known using synthetics or colloids such as fish glue with a sensitizer. Kodak had much of the early PWB market with their KPR and KMER Liquid resists based on polyvinyl cinnamate chemistry. These were the photoresists of choice in the early days, but under production conditions they were slow photographically and uniform coatings free of pinholes were difficult to achieve. 

The science of photopolymerization has been reviewed elsewhere and it is not the intent of this section to present any detailed discussion of that. Inventions aside, there are many practicalities that enter into the picture when developing a successful commercial product. While the above only skimmed the basic concept of a photoresist, the entire process and the various subtleties as well as market factors all had their effects on the various products that were developed for the market over time. And always there are many trade offs to be made. In formulating the various products that were marketed, often the performance for one important parameter comes at the expense of sacrificing performance in another important one. Commercial reality is that processes needed to be highly reliable and reproducible, free of problems, quick, inexpensive and have minimal health and environmental effects. 

Compositionally the RISTON films are composed of polymeric binders, which are the film formers, multifunctional acrylate monomers for their ability to rapidly polymerize and 

These methods of fabrication are called subtractive since copper sheets, typically 1.4 mils thick, cover the entire panel at the start of the process. Most of that copper has to be etched 

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HABIs in DuPont Photopolymer Films for the Electronics Industry... 

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