Copper-Ceramic Brazing Composition to Suppress Brittle Joint Phases
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Solution Overview
Problem
The existing copper-ceramic joint techniques face challenges in achieving high joint strength, particularly due to issues like localized formation of brittle compound phases and voids in the joint layer, which reduce the shear and tensile strengths of the joint.
Innovation Solution
A copper-ceramic joint body is formed using a brazing member containing Cu, Mg, and active metal elements like Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, and Er, with a specific at% ratio, which suppresses the formation of brittle phases and voids, creating a strong and ductile joint layer with enhanced shear and tensile strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active metal brazing member not containing Ag is used, then cost is reduced and Ag migration is prevented, but joint strength is insufficient
Solution Approach 1:
The invention changes the compositional parameters of the brazing member by specifying precise ranges of Cu (65-95 at%), Mg (4.5-33 at%), and active metal elements (0.1-7 at%). This parameter optimization prevents brittle compound phase formation while achieving shear strength ≥10 MPa, resolving the contradiction between joint strength and harmful phase formation.
Solution Approach 2:
The invention creates a composite brazing material system combining Cu, Mg, and active metal elements (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, Gd, or Er). This composite composition achieves both high joint strength and suppression of brittle phases through synergistic effects of the multiple elements.
2Reliability
If a brazing member containing Mg and active metal elements is used, then brittle phase formation is suppressed, but manufacturing precision of composition control is challenging
Solution Approach 1:
The invention establishes wide but controlled compositional ranges (Cu: 65-95 at%, Mg: 4.5-33 at%, active metals: 0.1-7 at%) that provide manufacturing flexibility while ensuring performance. These parameter ranges make composition control achievable in industrial manufacturing while maintaining joint strength ≥10 MPa.
3Reliability
If Ag-containing brazing member is used, then joint strength is achieved, but Ag migration occurs and cost increases
Solution Approach 1:
The invention extracts and removes Ag from the brazing member composition, replacing it with Mg and active metal elements. This extraction eliminates Ag migration problems while maintaining joint strength through the new compositional system of Cu-Mg-active metal elements.
Solution Approach 2:
The invention replaces expensive Ag with cheaper Cu and Mg-based composition, reducing material cost while achieving the required joint strength performance. The Cu-Mg-active metal system provides a cost-effective alternative to Ag-containing brazing materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The joint strength is significantly increased, with shear strength equal to or higher than 10 MPa and tensile strength equal to or higher than 17.3 MPa, ensuring a robust connection between copper and ceramic members.
Implementation Method 1
a technique using an active metal brazing member containing silver (Ag) is known
Implementation Method 2
a step of heating and retaining a layered body made of the copper member and the ceramic member while being pressurized in a layer
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A copper-ceramic joint body having high joint strength is provided. The copper-ceramic joint body includes: a copper member made of Cu or Cu alloy; a ceramic member joined to the copper member and made of nitride of Si or Al; and a joint layer formed on joint surfaces of the copper member and the ceramic member, and containing Cu and Mg and further containing at least one type of active metal elements selected from a group of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ca, Y, Ce, La, Sm, Yb, Nd, Gd and Er, and shear strength of the joint layer is equal to or higher than 10 MPa.