To obtain powder capable of improving fluidity of encapsulating materials used for any kind of epoxy resin by specifying the ratio of a specific surface area to an average particle size and the weight of particles having a particle size below a specified size.
This powder has a ratio of a specific surface area (m2/g)/an average particle size (μm) of 15-17 and 65-100 wt.% weight of particles having ≤1 μm particle size. The powder is manufactured by injecting and thermally treating inorganic raw material powder into hot flame which is formed from a combustible gas and a combustion improving gas. The raw material powder having a 3-12 μm average particle size and 0-15 wt.% particles having a ≤1 μm particle size is injected into the hot flame and obtained spherical fused powder is treated with classification. As materials of the spherical powder, alumina and silica are generally used and as an auxiliary agent of an encapsulating material or a filler, amorphous silica is preferably used. The inorganic filler is a matrix inorganic filler incorporated with a small quantity of the spherical inorganic powder and the ratio is preferably 1-20 wt.% in an internal ratio.
NAGASAKA HIDEAKI
KOBAYASHI AKIRA
Next Patent: SPHERICAL SILICA