Abstract: A preparation method of a high-thermal-conductivity and net-size silicon nitride ceramic substrate includes the following steps: (1) mixing an original powder, a sintering aid, a dispersant, a defoamer, a binder, and a plasticizer in a protective atmosphere to allow vacuum degassing to obtain a mixed slurry; (2) subjecting the mixed slurry to tape casting and drying in a nitrogen atmosphere to obtain a first green body; (3) subjecting the first green body to shaping pretreatment to obtain a second green body; (4) subjecting the second green body to debonding at 500° C. to 900° C. to obtain a third green body; and (5) subjecting the third green body to gas pressure sintering in a nitrogen atmosphere at 1,800° C. to 2,000° C. to obtain the high-thermal-conductivity and net-size silicon nitride ceramic substrate.

Abstract: The present disclosure relates to a method for preparing a silicon nitride ceramic material. The method including: (1) with at least one of silicon powder and silicon nitride powder as original powder and Y2O3 powder and MgO powder as sintering aids, the original powder and the sintering aids are mixed in a protective atmosphere, and the mixture is formed into a green body; (2) the resulting green body is put into a reducing atmosphere and pretreated at 500° C. to 800° C. to obtain a biscuit; and the reducing atmosphere is a hydrogen/nitrogen mixed atmosphere with a hydrogen content not higher than 5%; (3) the resulting biscuit is put into a nitrogen atmosphere and subjected to low-temperature heat treatment at 1600° C. to 1800° C. and high-temperature heat treatment at 1800° C. to 2000° C. in sequence.

Abstract: The present disclosure relates to a batch sintering method for a high-property silicon nitride ceramic substrate. The batch sintering method includes: (1) silicon nitride ceramic substrate green bodies are stacked and put into a boron nitride crucible, and a layer of boron nitride powder is applied between adjacent silicon nitride ceramic substrate green bodies; (2) after step-by-step vacuumization, debinding is performed in a nitrogen atmosphere or a reducing atmosphere at 500° C. to 900° C.; (3) gas pressure sintering is then performed in a nitrogen atmosphere at 1800° C. to 2000° C., completing the batch preparation of the high-property silicon nitride ceramic substrate.

Abstract: A preparation method for a copper plate-covered silicon nitride ceramic substrate is provided. The structure of the copper plate-covered silicon nitride ceramic substrate includes a silicon nitride ceramic substrate, copper sheets disposed on the upper and lower sides of the silicon nitride ceramic substrate and soldering layers disposed between the copper sheets and the silicon nitride ceramic substrate; the composition of the silicon nitride ceramic substrate comprises a silicon nitride phase (more than or equal to 95 wt %); and a grain boundary phase (containing at least three elements (Y, Mg and O) and less than or equal to 5 wt %, and the content of a crystalline phase in the grain boundary phase is more than or equal to 40 vol %); and the sintering aids are Y2O3 and MgO. The two-step sintering process comprises: in a nitrogen atmosphere, performing low-temperature heat treatment and high-temperature heat treatment in sequence.