Copper-Ceramic Bonded Structure for Migration-Resistant Insulating Boards
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for bonding copper and ceramic substrates face issues such as ceramic deterioration, migration, partial discharge, and uneven interfacial reactions, which hinder reliable bonding and electrochemical migration resistance, especially in high-voltage applications.
Innovation Solution
A bonded body of copper and ceramic is formed with a magnesium oxide layer on the ceramic side and a Mg solid solution layer containing active metals like Ti, Zr, or Hf, promoting uniform interfacial reactions without the use of Ag, ensuring reliable bonding and excellent electrochemical migration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If copper sheets are directly bonded to ceramic substrate by DBC method, then bonding strength is improved, but ceramic substrate deteriorates due to high bonding temperature (1065°C or higher)
Solution Approach 1:
The patent introduces a multi-layer intermediate structure between copper and ceramic substrate consisting of: (1) a copper oxide layer formed on the copper sheet surface, (2) a spinel layer containing Cu, Al, and O formed at the interface, and (3) a copper aluminate layer formed adjacent to the spinel layer. This intermediate structure enables bonding at lower temperatures (800-950°C) while maintaining strong bonding strength and preventing ceramic substrate deterioration.
Solution Approach 2:
The patent changes the bonding temperature parameter from the conventional DBC method's 1065°C or higher to a lower range of 800-950°C. This parameter change is achieved through the formation of specific interfacial compounds (spinel and copper aluminate layers) that enable bonding at reduced temperatures, thereby preventing ceramic substrate deterioration while maintaining adequate bonding strength.
2Reliability
If Ag-Cu-Ti based brazing material is used for bonding, then wettability and bonding reliability are improved, but electrochemical migration occurs due to Ag presence at bonding interface
Solution Approach 1:
The patent extracts and eliminates silver (Ag) from the bonding interface composition. Instead of using Ag-Cu-Ti brazing material, the patent forms a bonding structure consisting of copper oxide layer, spinel layer (Cu-Al-O), and copper aluminate layer, completely removing Ag to prevent electrochemical migration while maintaining bonding reliability through the interfacial compound layers.
Solution Approach 2:
The patent creates a composite interfacial structure with multiple functional layers: copper oxide layer providing initial adhesion, spinel layer (Cu-Al-O) providing intermediate bonding, and copper aluminate layer providing structural stability. This composite material approach at the interface achieves bonding reliability without requiring Ag, thereby preventing electrochemical migration.
3Temperature
If Cu-Mg-Ti alloy powder is used as brazing material, then bonding temperature is lowered and Mg sublimates, but gas remains at bonding interface causing partial discharge
Solution Approach 1:
The patent uses copper oxide and interfacial compounds (spinel and copper aluminate layers) as intermediaries to enable low-temperature bonding. This approach achieves bonding at 800-950°C without using Mg-based brazing materials, thereby avoiding Mg sublimation and the formation of gas pockets that would cause partial discharge.
Solution Approach 2:
The patent converts the potential harm of low-temperature bonding (insufficient bonding strength) into a benefit by forming specific interfacial compounds (spinel and copper aluminate layers) that provide strong bonding at lower temperatures. This eliminates the need for Mg-based materials and prevents gas formation and partial discharge.
4Strength
If high bonding temperature is used to achieve strong bonding, then bonding strength is improved, but electrochemical migration resistance deteriorates
Solution Approach 1:
The patent changes the bonding temperature parameter to an optimized range of 800-950°C, which is lower than conventional DBC methods. This parameter change achieves adequate bonding strength through the formation of spinel and copper aluminate interfacial layers, while the lower temperature inherently improves electrochemical migration resistance by reducing thermal activation of migration processes.
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 robust bonding between copper and ceramic substrates with improved electrochemical migration resistance, suppressing cracking and deterioration, even under thermal cycles and high voltage conditions.
Implementation Method 1
a magnesium oxide layer which is formed on a ceramic member side between the copper member and the ceramic member
Implementation Method 2
a Mg solid solution layer which is formed between the magnesium oxide layer and the copper member and contains Mg in a state of a solid solution in a Cu primary phase
Implementation Method 3
one or more active metals selected from Ti, Zr, Nb, and Hf are present in the Mg solid solution layer
Implementation Method 4
intermetallic compound phases containing Cu and the active metal may be dispersed in the Mg solid solution layer
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A bonded body of copper and ceramic includes: a copper member (12) made of copper or a copper alloy and a ceramic member (11) made of an aluminum oxide, the copper member (12) and the ceramic member (11) being bonded to each other; a magnesium oxide layer (31) which is formed on a ceramic member (11) side between the copper member (12) and the ceramic member (11); and a Mg solid solution layer (32) which is formed between the magnesium oxide layer (31) and the copper member (12) and contains Mg in a state of a solid solution in a Cu primary phase, in which one or more active metals selected from Ti, Zr, Nb, and Hf are present in the Mg solid solution layer (32).