Chemical structures and properties of low thermal expansion coefficient polyimides

Abstract

The relationships, between chemical structures of various aromatic polyimides and their thermal expansion coefficients, were investigated and the properties of low thermal expansion polyimides were elucidated. Such low values were observed for polyimides obtained from pyromellitic dianhydride or 3,3'.4,4'-biphenyltetracarboxylic dianhydride and aromatic diamines. which included only benzene or pyridine rings fused at para-positions without a flexible linkage. It was proposed that these low thermal expansion coefficients were related to the lineerity of their polymer molecular skeletons. In particular, PIQ-Ll 00 (Hitachi Chemical Co. Ltd) i s one such low thermal expansion polyimide and, it has excellent mechanical properties, thermal stability, and low absorbed moisture content.

Interfacial sliding in Cu/Ta/polyimide high density interconnects as a result of thermal cycling

“…Polyimide chains typically assume a nominally rigid rod configuration due to the ring structure in the polymer backbone. 3, 4 The orthotropic nature of the elastic and thermal expansion properties is attributed to the alignment of the polyimide chains in the plane of the film. 5,6 This paper reports on the use of an atomic force microscope (AFM) to study deformation in a single level Cufra/polyimide HDIC as a result of the imidization thermal cycle.…”

Organic-inorganic hybrid materials. II. Chain mobility and stability of polysiloxaneimide-silica hybrids

“…The results may be due to the fact that the coefficient of thermal expansion of the polyimide (ϳ 30 ppm/K) is larger than that of the silica (0.5 ppm/K). 21 However, the 29 Si-NMR spectra of hybrids 8B-50 and 10B-50 [ Fig. 3(E, F)] are similar to that of 6B-50, and their degree of condensation is independent of the hydrolysis ratio (Table II).…”

“…20 However, polyimides exhibit relatively high values of water sorption and coefficients of thermal expansion, impeding electronic applications. 21 A silica (SiO 2 ) exhibiting very low values of water sorption and coefficient of thermal expansion would be more suited for electronic applications. But the dielectric properties, planarizability, and patternability of silica are inferior to polyimides.…”

Polymeric Materials for Electronics Packaging and Interconnection

“…If expansion causes the thickness of the dielectric layer to exceed the length of the via, there is a risk of breaking the electrical connections between the layers of circuitry in the via, thus rendering the device inoperative. Relatively low CTE's have been realized in polymers in which the polymer chains can be oriented in a parallel direction (24)(25)(26).…”