We have developed tiny hollow silica particles with an elliptical shape and an average particle diameter of less than 2 μm. Hollow silica particles are hollow inside and have become popular as additives for paints and filler agents for resin products because of their lightweight and heat-insulating characteristics. In addition, with regard to the 5th generation mobile communication system(5G) that has been developed in recent years, it is expected to improve electrical properties with a smaller relative dielectric constant(Dk) than that of fused silica used for electronic substrates.
Specifically, the current 5G frequency band is 5 GHz, but it is expected to shift to a higher frequency band of 28 GHz or higher in the next few years. Electronic material substrates will have problems with transmission loss and heat generation under high frequencies, and lower dielectric properties of materials are required to solve these problems. At the same time, electronic devices and base stations required for communication are also becoming smaller, and electronic materials themselves are required to be smaller and thinner.
However, most of the hollow silicas on the market are hollow particles with particle diameters in the small size range of several hundred nm and in the size range of over 10 μm. If the particle size is too small, it is difficult to enhance the effect of low-dielectric properties, and if it is larger than several tens of micrometers, it is difficult to respond to thinning and miniaturization of the base material. We have developed a hollow silica that has a composition of amorphous silica, an elliptical shape, a particle size of 1 to 1.9 μm, a hollow ratio of 50 to 70 %, a filler dielectric constant(Dk) of 1.6 to 1.7, and a filler dielectric tangent(Df) of about 0.001.
In addition, our hollow silica has the potential to provide optical and mechanical properties that are not available with the spherical hollow particles that currently comprise the majority of the market.