	US 12,351,524 B2
	Preparation method for copper plate-covered silicon nitride ceramic substrate
Xuejian Liu, Shanghai (CN); Hui Zhang, Shanghai (CN); Xiumin Yao, Shanghai (CN); Yan Liu, Shanghai (CN); Jindi Jiang, Shanghai (CN); Zhengren Huang, Shanghai (CN); and Zhongming Chen, Shanghai (CN)
Assigned to SHANGHAI INSTITUTE OF CERAMICS, CHINESE ACADEMY OF SCIENCES, Shanghai (CH)
Appl. No. 18/261,078
Filed by SHANGHAI INSTITUTE OF CERAMICS, CHINESE ACADEMY OF SCIENCES, Shanghai (CN)
PCT Filed Jan. 17, 2022, PCT No. PCT/CN2022/072347 § 371(c)(1), (2) Date Jul. 11, 2023, PCT Pub. No. WO2022/156634, PCT Pub. Date Jul. 28, 2022.
Claims priority of application No. 202110075100.0 (CN), filed on Jan. 20, 2021.
Prior Publication US 2024/0067577 A1, Feb. 29, 2024
Int. Cl. B23K 37/00 (2025.01); C04B 35/584 (2006.01); C04B 37/00 (2006.01)

CPC C04B 37/006 (2013.01) [C04B 35/584 (2013.01); C04B 2237/125 (2013.01)]

12 Claims

1. A preparation method for a copper plate-covered silicon nitride ceramic substrate, wherein a structure of the copper plate-covered silicon nitride ceramic substrate comprises a silicon nitride ceramic substrate, copper sheets disposed on an upper side and a lower side of the silicon nitride ceramic substrate and soldering layers disposed between the copper sheets and the silicon nitride ceramic substrate; a composition of the silicon nitride ceramic substrate comprises a silicon nitride phase and a grain boundary phase; a content of the silicon nitride phase is more than or equal to 95 wt %; the grain boundary phase is a mixture containing at least three elements, wherein the at least three elements are Y, Mg and O, a composition and a content of the grain boundary phase are controlled by a two-step sintering process, so that the content of the grain boundary phase is less than or equal to 5 wt %, and a content of a crystalline phase in the grain boundary phase is more than or equal to 40 vol %; sintering aids for preparation of the silicon nitride ceramic substrate are Y₂O₃and MgO, a molar ratio of Y₂O₃to MgO is (1.0 to 1.4): (2.5 to 2.9), and the two-step sintering process comprises: in a nitrogen atmosphere with an atmospheric pressure of 0.5 MPa to 10 MPa, performing low-temperature heat treatment at 1600° C. to 1800° C. and high-temperature heat treatment performed at 1800° C. to 2000° C. in sequence; a thickness of the silicon nitride ceramic substrate is 0.2 mm to 2.0 mm; the composition of each of the soldering layers is AgCuTi, wherein a weight ratio of Ag:Cu:Ti is x:y:z, where x is equal to 0.60 to 0.65, y is equal to 0.33 to 0.37, z is equal to 0.01 to 0.04, x+y+z=1, and a thickness of each of the soldering layers is 20 to 60 microns; a thickness of the copper sheet is 0.1 mm to 1.5 mm; the copper sheets, solder foils forming the soldering layers and the silicon nitride ceramic substrate are stacked according to the structure of the copper plate-covered silicon nitride ceramic substrate, and after debinding in a protective atmosphere, vacuum soldering is performed at 860° C. to 920° C. kept for 5 to 20 minutes to obtain the copper plate-covered silicon nitride ceramic substrate.