New Light‐Sensitive Positive‐Working Thick Resist Materials forVarious Electronic Applications

Two different systems of light-sensitive resist materials precoated on carrier foils and their potential applications for thickfilm-technology and high quality printed circuits are described. In addition to 25 μ m diazo screen printing film already accepted in this field, new experimental films up to 70 μ m thickness can be provided. They show excellent shelf-life and can be transferred to the screen and developed after exposure simply with water. The second system is a 12 μ m positive dry film resist based on the same chemistry as all positive liquid resists. After lamination to a substrate it can be exposed directly on the resist. It gives better resolution than negative dry film resists and offers a potential for multiple exposure. Thicker positive dry films are possible using a new positive system without diazo compounds.