Kapton, polyimide manufacture

Dimensional Stability The dimensional stability of Kapton polyimide film depends on two factors— the normal coefficient of thermal expansion and the residual stresses placed in the film during manufacturing. The latter causes Kapton to shrink on its first exposure to elevated temperatures as indicated in the bar graph in Fig. 22-05. Once the film has been exposed, the normal values for the thermal coefficient of linear expansion, as shown in Table 22-04, can be expected. ]... 

Kapton is an example of an insulating pol3rmer that can be laser-carbonized to form conducting filaments. This substrate is flexible, inexpensive, durable and easy to manufacture. While the Kapton polyimide is a good insulator, research has shown that the laser-carbonized filaments are fair conductors. Additional opportunities to increase the effectiveness of some sensor designs lie in the fact that the carbonized filaments are porous and their resistivity can be manipulated easily during processing[46]. 

Only one type of electrical grade polyimide is available in film form and this is manufactured by DuPont under the trade name Kapton . Kapton polyimide is formed by the polycondensation of pyromellitic dianhydride and 4,4 -diamino diphenylether. The reaction proceeds via the intermediate formation of the polyamic acid as described in Section... 

This new zeolite-catalyzed ring-shift isomerization could provide a new route to anthracene and its derivatives [Song, 1996], which are valuable chemicals in demand, from phenanthrene, which is rich in liquids from coal. Selective partial hydrogenation of phenanthrene would be needed as the first step. Possible applications of sym-OHAn include the manufacturing of anthracene (for dyestuffs and fine chemicals), anthraquinone (pulping agent), and pyromellitic dianhydride (the monomer for polyimides such as Du Pont s Kapton) [Song and Schol rt, 1993]. Fundamental research is needed to clarify the mechanisms and reaction pathways. 

The aromatic amine di(4-aminophenyl)ether is employed in the manufacture of polyimide film, designated as Kapton (Du Pont). Other commercial materials of this type introduced by Du Pont in the early 1960s included a coating resin (Pyre ML) and a machinable block form (Vespel). In spite of their high price these materials have found established uses because of their exceptional heat resistance and good retention of properties at high temperatures. 

The first reported synthesis of an aromatic polyimide was in 1908 (1). However, much of the credit for the development and commercialization of polyimide products goes to DuPont, who benchmarked thi.s endeavor in the 1960s with the release of Kapton H film, Vespel molded parts, and Pyre-ML wire varnish (2). This effort inspired other researchers in academia, industry, and government laboratories to piusue the chemistry, fabrication, and appUcations of pol3rimides not envisioned several decades ago. There are several excellent books that address the extensive topic of polyimides (3-6). This article provides an overview of the field of polyimides from ssmthesis and basic kinetic behavior to fabrication and articles of manufacture. 

Table III lists the properties of perfluorinated polyimides, along with those of partially fluorinated and unfluorinated polyimides. The structure of PMDA/ODA is the same as that of Dupont s Kapton. Because of the direct introduction of fluorines into the aromatic rings and the flexible structure of the lOFEDA component, the polymer decomposition temperatures and Tg s of perfluorinated polyimides are slightly lower than those of conventional poly imides. The thermal stability of these films is nonetheless high enough to withstand the manufacturing process for IC s and muitichip modules.

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