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Mesoporous Silica Nanoparticles: A Potential Inorganic Filler to Prepare Polymer Composites with Low CTE and Low Modulus for Electronic Packaging Applications

For electronic packaging applications, polymer based SiO2 composites with low CTE and low elastic modulus are of great importance to the thermal or mechanical stress relief and reliability improvement. However, it's still a great challenge to achieve these goals simultaneously by incorporating conventional SiO2 filler into resin matrix. In this study, we prepared the mesoporous SiO2 filler through a modified Stöber approach and then comparatively investigated the viscosities and thermomechanical performance such as modulus, glass transition temperature (Tg) and CTE, etc. of composites filled with mesoporous and nonporous SiO2 filler. The results showed the mesoporous SiO2 fillers was more effective to lower the CTE values as compared with spherical SiO2 fillers without mesopores. It means that much lower SiO2 loading is needed to achieve a desired CTE value using mesoporous silica as fillers and thus the modulus of obtained composites can be controlled at a lower level. Therefore, our results provide an effective approach to overcome the conflicting requirements between the low CTE and low modulus of polymer based composites. Besides, compared with nonporous SiO2 composites, mesoporous SiO2 composites exhibit higher transparency, higher Tg and higher adhesive strength, which makes mesoporous SiO2 a promising filler for electronic packaging applications.