Kodak positive resists

Resists as different as naturally occurring colloids (such as gelatin, albumin, and shellac) or synthetic polymers (such as polyvinyl alcohol, polyacrylics, polyvinyl pyrrolidone, and polyvinyl hutyral) rendered photosensitive by dichromate or other means, as well as synthetic photosensitive polymers such as polyvinyl cinnamates (Kodak positive resists), diazonaphthoquinone/novolac, and solid-film resists such as Riston (introduced by Dupont in 1968) have all been used in PCB fabrication. Some of these resists are still being used today. 

Kodak Micro Positive Resist 820," Kodak Publication No. G-103 (1983)... 

However for intermediate compositions (32-50% in CHDM) they formed homogeneous mixtures above an upper critical solution temperature (UCST) that rendered a miscible metastable phase upon quenching. A thermodynamic analysis of the USCT-type behavior demonstrated that the bare interaction energy for each pair of blends, was positive and increased with the content of 1,4-CHDM units in the copolymer (140). Commercial PEj.C -T/ PC blends (Ektar DA series, Eastman Kodak) have been used in lawn and garden equipment, floor care appliance parts, sterilizable medical equipment, etc. In these applications, a beneficial combination of clarity, toughness, chemical resistance, heat, UV and gamma radiation resistance has been profited. Molded parts made of these blends generally showed excellent surface finish and hence molded-in-color could be used (141). 

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