Copper-Ceramic Bonded Assembly for Lower-Temperature High-Strength Joining
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Solution Overview
Problem
Existing copper/ceramic bonded bodies face challenges with high bonding temperatures that can deteriorate ceramic substrates, and they struggle to maintain bonding strength under severe thermal cycles.
Innovation Solution
A copper/ceramic bonded body with an active metal compound layer containing Ti, Zr, Nb, or Hf, where Al and Cu are present at the grain boundary, forming a liquid phase for enhanced interfacial reaction and bonding, and Ag can be added to lower the eutectic temperature, promoting a strong and reliable bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the DBC method is used to bond copper sheet and ceramic substrate, then bonding strength is improved, but bonding temperature must be set to 1065°C or higher which causes ceramic substrate deterioration
Solution Approach 1:
An active metal compound layer (containing Ti, Zr, Nb, or Hf compounds) is introduced as an intermediary layer between the copper member and ceramic member. This intermediate layer enables bonding at lower temperatures by facilitating chemical reactions that form strong interfacial bonds without requiring the high temperatures needed for direct copper-ceramic bonding, thus preventing ceramic substrate deterioration while maintaining bonding strength.
Solution Approach 2:
The invention changes the bonding mechanism from direct copper-ceramic contact to copper-active metal compound-ceramic bonding. By introducing the active metal compound layer, the bonding temperature parameter is reduced from 1065°C or higher to a lower temperature range, while the bonding strength is maintained through the formation of strong interfacial reactions at the copper-active metal compound and active metal compound-ceramic interfaces.
2Strength
If active metal brazing method is used with Ag-Cu-Ti-based brazing material, then wettability and bonding are improved, but bonding temperature is set to 900°C which causes ceramic substrate deterioration
Solution Approach 1:
The active metal compound layer serves as an intermediary that enables direct or near-direct bonding between copper and ceramic without requiring a thick brazing material layer. This reduces the bonding temperature from 900°C to a lower temperature range while maintaining strong bonding through the formation of strong interfacial reaction layers.
3Stability of the object's composition
If bonding temperature is reduced to prevent ceramic deterioration, then ceramic integrity is improved, but bonding strength between copper and ceramic decreases
Solution Approach 1:
The active metal compound layer acts as a mediator that enables strong bonding between copper and ceramic at lower temperatures. The active metal compounds (Ti, Zr, Nb, or Hf compounds) form strong chemical bonds with both copper and ceramic, creating a robust intermediate layer that maintains bonding strength even when bonding temperature is reduced to preserve ceramic integrity.
Solution Approach 2:
The bonded structure becomes a composite system consisting of copper member + active metal compound layer + ceramic member. This composite structure leverages the complementary properties of each layer: copper provides electrical conductivity and ductility, the active metal compound layer provides strong interfacial bonding and chemical stability, and the ceramic provides thermal and electrical insulation. This composite approach enables strong bonding at lower temperatures while maintaining ceramic integrity.
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 solution achieves high bonding strength and improved thermal cycle reliability by ensuring a firm bond between copper and ceramic members, suppressing crack generation and maintaining integrity under severe thermal conditions.
Implementation Method 1
forming a liquid phase for enhanced interfacial reaction and bonding
Implementation Method 2
enhanced interfacial reaction and bonding
Implementation Method 3
Ag can be added to lower the eutectic temperature, promoting a strong and reliable bond
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
This copper/ceramic bonded body (10) includes: a copper member (12, 13) made of copper or a copper alloy; and a ceramic member (11) made of aluminum-containing ceramics, the copper member (12, 13) and the ceramic member (11) are bonded to each other, in which, at a bonded interface between the copper member (12, 13) and the ceramic member (11), an active metal compound layer (41) containing an active metal compound that is a compound of one or more active metals selected from Ti, Zr, Nb, and Hf is formed on a ceramic member (11) side, and in the active metal compound layer (41), Al and Cu are present at a grain boundary of the active metal compound.