Abstract: A preparation method for a spherical silica powder filler, comprises the following steps: S1, providing spherical polysiloxane comprising T units by means of a hydrolysis condensation reaction of R1SiX3, wherein R1 is hydrogen atom or an independently selectable organic group having 1 to 18 carbon atoms, X is a hydrolyzable group, and the T unit is R1SiO3—; and S2, calcining the spherical polysiloxane under the condition of a dry oxidizing gas atmosphere at a calcining temperature between 850° C. and 1200° C., so as to obtain a spherical silica powder filler having a low hydroxyl content. The spherical silica powder filler is composed of at least one selected from Q1 unit, Q2 unit, Q3 unit and Q4 unit, wherein Q1 unit is Si(OH)3O—, Q2 unit is Si(OH)2O2—,Q3 unit is SiOHO3—, Q4 unit is SiO4—, and the content of Q4 unit is greater than or equal to 95%.

Abstract: A preparation method for a spherical silica powder filler comprises the following steps: S1, providing spherical polysiloxane comprising a T unit by means of a hydrolysis condensation reaction of R1SiX3, wherein R1 is hydrogen atom or an organic group having independently selectable 1 to 18 carbon atoms, X is a hydrolyzable group, and T unit is R1SiO3—; and S2, calcining the spherical polysiloxane under the condition of a dry oxidizing gas atmosphere, the calcining temperature being between 850° C. and 1200° C., so as to obtain the spherical silica powder filler which does not contain silica particles of which the diameter is less than 50 nanometers. The spherical silica powder filler does not contain silica particles of which the diameter is less than 50 nanometers, has a low dielectric loss and a low thermal expansion coefficient, and is suitable for high-frequency high-speed circuit boards, prepregs or copper clad laminates, etc.

Abstract: A preparation method for a spherical or angular powder filler, comprising: providing spherical or angular siloxane comprising a T unit, wherein the T unit is R1SiO3?, and R1 is a hydrogen atom or an organic group which can be independently selected from carbon atoms 1-18; and performing heat treatment on the spherical or angular siloxane under an inert gas atmosphere or atmospheric atmosphere, the heat treatment temperature being between 250 degrees and 650 degrees, so that silicon hydroxyl groups in the spherical or angular siloxane are condensed to obtain the spherical or angular powder filler. In the unit T of the spherical or angular powder filler, the content of the unit without containing a hydroxyl group in the total unit is greater than or equal to 95%, and the content of the unit containing one hydroxyl group in the total unit is less than or equal to 5%. Also disclosed are the spherical or angular powder filler obtained by the preparation method, and application thereof.