Copper-Ceramic Bonding Interface Using Mg-N Anchoring Against Weld Cracks
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Solution Overview
Problem
Insulating circuit substrates with copper and ceramic bonding face issues of peeling and crack generation when subjected to ultrasonic welding, as existing bonding methods do not provide sufficient strength and stability at the bonded interface.
Innovation Solution
A copper/ceramic bonded body is created using a Mg—N compound phase that extends from the ceramic member to the copper member, with a sufficient number density and Si concentration to ensure a strong anchor effect, and a method involving Mg disposition, lamination, and controlled heating treatment to form a robust interfacial reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bonding methods (Ag-Cu-Ti or Cu-Mg-Ti brazing materials) are used to bond copper sheet to ceramic substrate, then bonding strength is improved, but cracks are generated at the bonded interface during ultrasonic welding
Solution Approach 1:
The invention changes the chemical composition parameters of the brazing material by replacing traditional Ag-Cu-Ti or Cu-Mg-Ti alloys with a Cu-Al- Ti-based brazing material containing specific amounts of Al (5-20 mass%) and Ti (3-10 mass%). This parameter change modifies the bonding mechanism to form Al2O3 ceramic layers at the interface, which have different mechanical properties that resist crack propagation during ultrasonic welding while maintaining strong bonding strength.
Solution Approach 2:
The invention creates a composite structure at the bonded interface by forming Al2O3 ceramic layers within the Cu-Al-Ti brazing material. This composite material combines the ductility of copper with the hardness and crack-resistance of aluminum oxide ceramic, providing both strong bonding strength and resistance to crack generation during subsequent ultrasonic welding operations.
2Stability of the object's composition
If Cu-Mg-Ti brazing material is used with heating at 560-800°C in nitrogen atmosphere, then Mg sublimation improves bonding by preventing Mg residue, but titanium nitride (TiN) formation may occur causing brittleness
Solution Approach 1:
The invention changes the heating temperature parameter to 700-900°C, which is higher than conventional methods. At this elevated temperature range, titanium nitride formation is suppressed while Mg sublimation continues effectively. The Al content (5-20 mass%) also plays a crucial role in preventing TiN formation by preferentially reacting with Ti to form Al2O3, thus maintaining bonding strength while ensuring composition stability.
3Strength
If Mg is used as bonding material to achieve strong bonding, then bonding strength is improved, but Mg residue at interface causes instability
Solution Approach 1:
The invention optimizes the heating temperature parameter to 700-900°C, which is sufficiently high to ensure complete Mg sublimation and prevent Mg residue at the bonded interface. This temperature parameter change maintains strong bonding strength through Al2O3 layer formation while simultaneously achieving composition stability by eliminating unstable Mg residues.
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 effectively suppresses peeling and crack generation during ultrasonic welding, ensuring a strong and reliable bond between copper and ceramic members, enhancing the durability of the insulating circuit substrate.
Implementation Method 1
a Mg—N compound phase extending from a ceramic member side to a copper member side is present at a bonded interface between the copper member and the ceramic member
Implementation Method 2
at least a part of the Mg—N compound phase enters into the copper member
Implementation Method 3
when ultrasonic waves are applied to bond the terminal material or the like
Implementation Method 4
cracks are generated at the bonded interface
Data Source
AI summary
This copper/ceramic bonded body includes: a copper member made of copper or a copper alloy; and a ceramic member made of silicon nitride, wherein the copper member and the ceramic member are bonded to each other, a Mg—N compound phase extending from a ceramic member side to a copper member side is present at a bonded interface between the copper member and the ceramic member, and at least a part of the Mg—N compound phase enters into the copper member.