| Epoxy resin has been wisely used in electronic packaging industries due to its ease of processing, low cost, excellent heat, moisture, and chemical resistance, superior electrical and mechanical properties, and good adhesion to many substrates. However, current organic based board materials such as epoxy resins are not suitable to meet the electronic industry requirement because of two main limitations; lack of board dimensional control because of war-page and distortion during the thermal cycling and the large coefficient of thermal expansion (CTE) mismatch between the substrate and silicon chip leading to solder joint failures. Upon cured, this multifunctional epoxy resin provides a densely crosslink protective layer; however, because of the difference in linear expansion coefficient between filler and epoxy resin, some imperfections are bora to molding compounds during curing, such as point defect, bulk, season cracking, etc.Negative thermal expansion (NET) materials have received considerable attention during the last decade. Cubic zirconium tungstate, ZrW2O8, has been used as an additive to control the thermal expansion properties of composite materials due to its relatively large isotropic, negative thermal expansion. Admixture of ZrW2O8 into cement, polyester, or epoxy polymers make composites exhibiting reduced thermal expansion properties. This article reported the synthesis of ZrW2O8 by solid-state reaction using chemical synthetic ZrO2 and WO3 as starting materials, and the fabrication of ZrW2O8/epoxy resin (E-51) polyimide electronic packaging materials in which the embedded filler particles appear to be in close contact with the polymer phase.Adopting High-low temperature diffraction and the Powder X software calculation, the average linear expansion coefficient of ZrW2O8 particle was about -5.02×10ppm/℃. Sample of SEM imaging showed the average particle diameter of ZrW2O8 synthesized by solid-state reaction was about 0.5～1μm.Compared with SiO2/E-51 composites, ZrW2O8/E-51 has the better tensile strength, flexural strength and anti-acid property. With more ZrW2O8 content, ZrW2O8/E-51 composites showed a decline in linear expansion coefficient and an increase in the mic-hardness. The results show that, with more ZrW2O8 content, the dielectric constant of ZrW2O8/E-51 increase, whereas the dielectric loss decline gradually. During room temperature and 163℃, ZrW2O8/E-51 composites show a steady bulk resistivity about 3.03×106Ω·m, and its breakdown field strength is in excess of 10KV/m, which is available to industry application. The wear mechanism of packaging materials of epoxy resin is adherence abrasion and abrasive wear. However, the moisture absorption rate and anti-alkali property were worse than those of SiO2/E-51 composites.Differential scanning calorimetric (DSC), Kissinger equation and Ozawa equation were employed to detect the kinetics of co-curing system. The apparent reactive activation energy (ΔE) of SiO2/E-51/706 and ZrW2O8/E-51/706 was 83.2 KJ/mol and 70.6 KJ/mol, respectively. Also the velocity constant of the two reactions were measured. |
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