Photoimageable polyimides

Photoimageable polyimides, 20 278-281 Photoimageable resists, 20 280. See also Photoresists... 

Moyer ES, Mohanty DK, Shaw J and McGrath JE (1989) Synthesis and characterization of soluble photoimageable polyimide and poly(imide siloxane) homo- and copolymers. 3rd International SAMPE Electronics Conference, p 894... 

Miyoshi, K. Suwa, A. Tomikawa, M. Alkali-developable photoimaging polyimide compositions for coatings or interlayer insulators of electronic devices. Jpn. Kokai Tokkyo Kobo JP 2003005369, 2003 Chem. Abstr. 2003,138, 98183. 

Manufacture of Printed Wiring Boards. Printed wiring boards, or printed circuit boards, are usually thin flat panels than contain one or multiple layers of thin copper patterns that interconnect the various electronic components (e.g. integrated circuit chips, connectors, resistors) that are attached to the boards. These panels are present in almost every consumer electronic product and automobile sold today. The various photopolymer products used to manufacture the printed wiring boards include film resists, electroless plating resists (23), liquid resists, electrodeposited resists (24), solder masks (25), laser exposed photoresists (26), flexible photoimageable permanent coatings (27) and polyimide interlayer insulator films (28). Another new use of photopolymer chemistry is the selective formation of conductive patterns in polymers (29). 

There are several ways (see Fig. 5) in which polyimides have been used in applications where photoimaging is required to produce a pattern on a substrate (typically silicon, or other materials including polyimide itself) (205). The first method is reactive ion etching (RIE) (includes plasma etching) or photoablation. This method does not require a photosensitive material, only a mask that can withstand the reactive ion gas or photons, and the material to be patterned, which is protected by the mask. In RIE, the reactive ions, generated by an RF field, attack the exposed polyimide to etch out the pattern of the mask. This process can be used with conventional polyimide film and requires few steps, but is not highly accurate and requires a hard (metal, silicon, etc) mask. The other methods... 

Base dielectrics Conductor materials Copper-clad laminates Coverlay Adhesive sheets Polyimide films (Kapton K, E, EN, KJ Apical NP, FP Upilex S) Liquid polyimide resin, PEN film, LCP films Ultra-thin copper foils, sputtered copper, copper alloys, stainless steel foil Adhesiveless laminates (cast type, sputtered/plated type, laminated type) Photoimageable coverlay (PIC) (dry film type, liquid ink type) Hot-melt polyimide film... 

Liquid Polyimide Resin (Photoimageable). Many new HDI apphcations require special capabilities and properties on the substrates that are not provided by commercial polyimide films. In these cases, circuit manufacturers initiate production by manufacturing polyimide substrates. Sometimes manufacturers have to start from the synthesis of polyimide... 

Several liquid polyimide resins have been developed as the base materials of high-density flexible circuits. Some of these liquid polyimide resins can be photoimaged, and have been used in high volume as the dielectric layer and coverlay in the wireless suspension of hard disk drives. 

New materials of photoimageable coverlay have been developed without bromine molecules. Not many choices offer a balanced performance, especially high flexibihties for dynamic flexing. Polyimide-based photoimageable coverlays are the solution to satisfy the all of the physical requirements, but these polyimide materials are remarkably more expensive. 

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