Incorporating negative thermal expansion Cu2V2O7 into epoxy to achieve low thermal expansion and high thermal conductivity

Thermal expansion mismatch among packing epoxy, silicon chip and copper microbump, generates severe thermal stress in 3D packaging and system in package . This inherent issue generally leads to warpage and interface crack of integrated circuit (IC). Furthermore, low thermal conductivity is equally disadvantageous to heat dissipation in electronic packing materials, especially for high power density IC. Consequently, the thermal expansion mismatch and low thermal conductivity concurrently result in the dilemma of IC and speed up structural failure. Conventionally, amorphous silica with the low thermal expansion is incorporated into the epoxy to design an epoxy molding compound in order to reduce the giant thermal expansion of epoxy. However, commercial epoxy/silica composites cannot effectively solve the critical issues of thermal expansion mismatch and low thermal conductivity. Here, the Cu 2 V 2 O 7 (CVO) with negative thermal expansion (NTE) was introduced into epoxy to design the unconventional Epoxy/CVO composites, which demonstrates suppressed thermal expansion and high thermal conductivity . When the mass fraction of CVO researches up to 60 %, the linear coefficient of thermal expansion of this composite decreases from 94.5 ppm·K ‐1 of epoxy down to a low value of 25.8 ppm·K ‐1 . Concurrently, this composite achieves a high thermal conductivity of 1.31 W·m ‐1 ·K ‐1 . Moreover, the resistivity, tensile strength , elastic modulus and thermal hardness are measured to be 9.3 × 10 10 Ω·m, 13.7 MPa, 7.4 MPa and 80.2 HD, respectively, close to the values of the ideal epoxy molding compound. This work develops an untraditional Epoxy/NTE composite and offers a systematic investigation of their thermal, mechanical and dielectric properties , which is highly helpful for the development of advanced electronic packaging materials.