Films and Coatings for Electronic Applications

PI films that are transparent and colorless find applications as liquid crystal display materials, optical communication materials, waveguide materials, or solar battery protection films.  

During fabrication, PI films are likely to turn yellow or brown due to thermal degradation resulting from severe thermal history. In order to fabricate high transparent films, special techniques must be employed. Including fluor atoms into the structure to make the materials more heat resistant. Another method consists of the following steps in film fabrication  

Heating the polyamic acid solution under reduced pressure to obtain a PI resin, 

Metallized PI films are used in electronic applications, e.g. for flexible printed circuit boards. Conventional techniques for the fabrication use adhesive bonding to a copper foil. However, the demand for high density packaging of electronic apparatuses requires a further reduction in the thickness of these substrates. It is possible to sputter metal particles into the surface of the PI film at a thickness of 20 nm, which forms the intermediate layer for subsequent formation of a conductive layer of copper or a copper alloy. 

PI resins find use as coverlays. A coverlay is generally used to protect printed circuits during subsequent processing, primarily solder operations, or from environmental effects during use. The Pis can be used in combination with epoxies. In addition, additives, such as phosphorous-based flame retardants or adhesion promoters, may be used in the formulations. 

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