Development of a new packaging material with superior high-temperature stability is becoming increasingly crucial in high-power and high-density electronics industry. In this study, we employed bis­(3-ethyl-5-methyl-4-maleimidephenyl)­methane (BMI), para-xylene phenolic resin (PF), and triphenylmethane novolac epoxy resin (EP) as matrix resins to develop high-temperature-stable BPE ternary resin molding compounds for power device packaging. BMI was first melt-blended with PF to obtain the premix with a reduced softening point for meeting the requirement of melt-kneading process. 2-Ethyl-4-methylimidazole with a dosage of 2 wt % of the ternary resins, could effectively promote the curing reaction, making the molding process of BPE molding compounds be compatible with that of the existing epoxy molding compounds (EMC). The introduction of BMI component could enhance the chain rigidity and heat resistance of cured resins. When the BMI content was more than 70 wt % of the ternary resins, the cured BPE molding compounds exhibited the glass transition temperature and initial decomposing temperature larger than 250 and 400 °C, respectively, indicating a much superior thermal performance to that of the cured EMC. Moreover, the flexural performance and the adhesion strength with copper at 260 °C, high-temperature aging resistance, dielectric properties, and thermal conductivity of the cured BPE molding compounds were also improved compared with those of the cured EMC. This study provides a promising strategy for preparing heat-resistant electronic packaging molding compounds.

For the molding compounds used in electronic packaging, curing accelerators play a significant effect on the curing behavior of thermosetting resins, thus the cross-linked structure and performance of the cured product. In this study, nine commercially available imidazole compounds, divided into three types, were introduced into a polyfunctional epoxy resin (E 1 )/XYLOK phenolic resin (P 1 )/MDA benzoxazine (B 1 ) ternary system to reduce the curing temperature for molding processing. To understand the cross-linked structure of the cured product, the ternary system was divided into unitary system and binary system, and the curing behavior and chemical structure of each system was monitored by differential scanning calorimetry and Fourier transform-infrared systematically.Due to the nucleophilicity of tertiary amines influenced by the steric hindrance effect, it was discovered that the reaction activity of epoxy resin initiated by nine imidazole compounds, was significantly different. However, the ring opening of benzoxazine occurs at a high temperature, even catalyzed with imidazoles, and its curing behavior was nearly the same owing to the unique ring-opening mechanism initiated by active hydrogen of imidazole. In addition, phenolic resin elevates reaction activity for both epoxy resin and benzoxazine. The cross-linked structure of E 1 P 1 B 1 ternary system was proposed based on the experimental results from each system. It suggested that the formed network of the E 1 P 1 B 1 cured product with Type I and II imidazoles is mainly IPN structure, while the cured products of E 1 P 1 B 1 + Type III is the copolymerization of epoxy, phenolic and benzoxazine. This paper systematically illustrated the ideal chemical structures of epoxy resin/phenolic resin/benzoxazine ternary system with different imidazole compounds, which is valuable for industrial application of resin-based materials.