Synthesis of epoxy acrylate and preparation of dual-curable ECAs based on conductive ceramic powders

Abstract

To achieve both excellent mechanical property and good electrical conductivity for electrically conductive adhesives (ECAs), epoxy acrylic resins were employed as polymer matrix as well as modified BaTiO₃ ceramic powders as conductive fillers by means of UV–thermal dual-curing method. In this paper, the epoxy acrylic resins with different esterification ratios were synthesized. Experimental studies show that epoxy acrylic resin with the esterification ratio of 5/8, has excellent performances on mechanical properties, gel ratio and thermal stability, and thus this specific material is suitable for polymer matrix. Based on the given esterification ratio of epoxy acrylic resin, the effects of diluent, photo-initiator, thermal initiator, thermal-curing agent, conductive fillers on mechanical and conductive properties of the ECAs were investigated. An optimum proportion of the ECAs’ ingredients is determined containing epoxy acrylic resin as matrix, 20 wt% of propylene oxide as diluent, 3.5 wt% of 2,4,6-trimethyl benzoyl-diphenyl phosphine oxide (TPO) as photo-initiator, 1.5 wt% of benzoyl peroxide (BPO) as thermal initiator, 10 wt% of triethanolamine as thermal-curing agent and 60 wt% of conductive ceramic powders as conductive fillers. In such condition, the volume resistivity of the ECA decreases to 5.30 × 10⁻² Ω m, and the ECA still has a moderate mechanical property with the peel strength of 5.71 MPa and peel strength of 2.10 kN m⁻¹. The ECA also exhibits excellent performance on thermal stability, and the SEM results show that the conductive fillers are well dispersed in the epoxy matrix without obvious agglomeration. The ECAs with epoxy acrylic resin and conductive ceramic powders have wide application prospects and potential economic value for electronic packing industry.