Poly(ester imide)s Possessing Low CTE and Low Water Absorption (II). Effect of Substituents

Abstract

The film properties of a variety of poly(ester imide)s (PEsIs) were evaluated for development of a novel high temperature base film in flexible printed circuit (FPC) boards. In this work, three types of PEsI systems were systematically prepared from the following combinations of monomers: (1) ester-containing tetracarboxylic dianhydrides: hydroquinone bis(trimellitate anhydride) (TAHQ), methyl-substituted TAHQ (M-TAHQ), and methoxy-substituted TAHQ (MeO-TAHQ) with common diamines such as p-phenylenediamine (PDA), (2) common tetracarboxylic dianhydrides such as pyromellitic dianhydride (PMDA) with ester-containing diamines: 4-aminophenyl-4 0 -aminophenylbenzoate (APAB) and methyl-substituted APAB (ATAB), and (3) the TAHQ series with the APAB series. The effects of the substituents on the PEsI film properties and polymerizability were also discussed in this work. The ester-containing monomers used in this work (TAHQ series and the APAB series) were all highly reactive and led to PEsAAs possessing high inherent viscosities ranging 1.09-9.33 dL/g. The incorporation of methyl and methoxy substituents into rigid TAHQ-based PEsI systems caused no significant decrease in T g but allowed molecular motions above the T g s. In some cases, these substituents, in particular, the methoxy group contributed to a significant decrease in water absorption without sacrificing other target properties. For practical FPC application, a flexible diamine was copolymerized into the highly esterified rigid PEsI systems derived from the TAHQ series with the APAB series. One of the PEsI copolymers obtained achieved excellent combined properties: a low CTE (17.8 ppm/K) completely consistent with that of copper foil as a conductive layer, considerably low water absorption (0.47 wt %), a high T g exceeding 360 C, and improved toughness (elongation at break > 40%). Polyimides (PIs) have been widely utilized in a variety of micro-and optoelectronic applications such as flexible printed circuit boards (FPC), chip on film (COF) assembling system, tape automated bonding tapes (TAB), buffer-coating films and interlayer dielectrics for LSI chips, high temperature adhesives, light wave guides for their combined excellent properties, i.e., high glass transition temperatures (T g ), high resistance to chemicals and radiation, relatively low dielectric constants, and good mechanical properties.1-10 The advantages of PI materials are considerably high purity (extremely low contents of metal contaminations and residual monomers and solvents) in the resins, simple fabrication processes, and the ease of structural modifications through copolymerization using various commercially available monomers.FPC, TAB, and COF are fabricated from PI film/Cu foil laminates (flexible copper clad laminates, FCCL or CCL). Adhesive-free FCCL has an advantage in the view point of dimensional stability against heat cycles compared to that using thermally less stable conventional adhesives. This type of FCCL is usually produced by the casting method (thermal imidization after s...

Optically transparent aromatic poly(ester imide)s with low coefficients of thermal expansion (1). Self-orientation behavior during solution casting process and substituent effect

“…We have previously reported the thermal and mechanical properties of thermally imidized PEsI films prepared from TFMB with non-substituted and methyl/methoxy-substituted TA-HQs without interests on the film transparency [22]. Then we began on evaluating the film transparency of these systems as the first step of the present work.…”

Crystal structure of bis(2-fluoro-4-nitrophenyl) terephthalate C20H10F2N2O8

“…Aromatic polyimides have been widely utilized and usually applied to a variety of electric, microelectronic, and optoelectronic devices due to their combined excellent properties, such as considerably high glass transition temperatures, high resistance to chemicals, good dielectric and mechanical properties [1]. However, even such combined properties of …”

Crystal structure of bis(2-trifluoromethyl-4-nitrophenyl) terephthalate — acetic acid (1:1), C24H14F6N2O10

“…Low CTE polyimides have been widely used in a variety of micro and optoelectronic applications, because of their combined excellent properties, including high glass transition temperature, high resistance to chemicals and radiation, and good mechanical properties [1]. The ester linkages in the title compound contribute to the stiff and almost linear structure, consequently improving the in-plane orientation during imidization and reducing CTE of the derived PIs [2].…”