Preparation and characterization of a high Tg cyanate ester/epoxy composite resin

Abstract

With the prohibition use of lead-solder, the reflow temperature was brought up to about 250 °C. The higher soldering temperature requires the substrate resins with better thermostability and higher glass transition temperature. The cyanate ester/epoxy composite resins are widely used in high frequency substrates for their excellent performance, such as low dielectric constant, low water absorption, high thermostability and dimensional stability. However, the glass transition temperature of the resin is generally less than 200°C. For better performance of the substrate in lead-free reflow soldering process, resins with improved glass transition temperature are required. In this paper, a multifunctional epoxide with a rigid triazine ring, 2,4,6-tris(4-glycidyloxy phenyl)-1,3,5-triazine (TGPT), was synthesized and used to make a composite resin with biscyanatophenylpropane in the mass ratio of 50%. 1-(2-Cyanoethyl)-2-ethyl-4-methylimidazole (2E4MZ-CN) was used as accelerator. The thermal and mechanical properties of the composite resin were characterized by dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). The glass transition temperature (Tg) of the composite resin was 280°C (tanδ) which was much higher than that of the biscyanatophenylpropane/bisphenol A diglycidyl ether composite resin (162°C, DSC). The storage modulus and coefficient of thermal expansion (CTE) of the resin was 3.0 GPa and 55.36 ppm/°C, respectively. Besides, the thermostability of the composite resin was measured by thermogravimetic analysis in the atmosphere of nitrogen. The 5% and 10% weight-loss temperature of the resin were 336°C and 348°C, respectively.