A P/N additive to optimise the flame retardancy, low dielectricity and mechanical properties of EP composites

For expanding the application of epoxy resin (EP) in semiconductor packaging, the P/N flame retardant containing azole ring, designated as BT, was designed, synthesized, incorporated into EP, and flame retardant EP (FREP) was prepared. These resins were tested in terms of their thermal stability, flame retardant properties, mechanical properties, and dielectric properties. Owing to the excellent biphasic flame retardancy of BT, the samples reached the V-0 class of UL-94 flammability standards at 5 wt% BT with a 35.3% Limited Oxygen Index (LOI), which is 31.7% higher than that of EP . At the addition of 15 wt% BT (i.e., EP/BT15), the cone calorimetry test indicated that the sample's total exotherm and peak exotherm rates were reduced by 34% and 42%, in comparison to pure EP, respectively. The mechanical properties of FREP improved, and the tensile and flexural strengths increased by 9% and 10%, respectively, at 10 wt% BT addition. Moreover, the dielectric constant and dielectric loss of FREP decreased with increasing BT content. In this work, a simple strategy for the preparation of EP with good transparency, mechanical properties, flame retardancy and low dielectric constant is provided.