Crystalline Active Metal Layer for Ceramic-Copper Bonding
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Solution Overview
Problem
In insulating circuit substrates, the use of active metal oxide layers formed on ceramic members can lead to cracking and peeling when ultrasonic waves are applied, due to the amorphous nature of these layers.
Innovation Solution
A bonded body is formed with a crystalline active metal compound layer, specifically a titanium compound, on the ceramic member side, which suppresses cracking and peeling by maintaining an optimal thickness range of 1.5 nm to 150 nm, and includes active metal nitrides or oxides for improved joining properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an amorphous active metal oxide layer is formed on the ceramic member side, then the ceramic member and copper member can be joined, but cracks may be generated and peeling may occur when ultrasonic waves are applied
Solution Approach 1:
The patent changes the physical state parameter of the active metal compound layer from amorphous to crystalline. This phase transition fundamentally alters the material's mechanical properties, making it resistant to cracking under ultrasonic vibration while maintaining effective bonding between the ceramic member and copper member.
Solution Approach 2:
The patent creates a composite structure at the interface between ceramic and copper members by forming a crystalline active metal compound layer. This intermediate layer combines the benefits of strong adhesion (from the active metal's reactivity) with crack resistance (from the crystalline structure), effectively decoupling the brittle ceramic from the ductile copper.
2Strength
If the thickness of the active metal oxide layer is increased to ensure joining strength, then the brazing joining strength is improved, but the brittleness increases and cracking may occur during thermal cycling
Solution Approach 1:
The patent changes the structural parameter of the active metal compound layer from amorphous to crystalline. This transformation allows the layer to maintain adequate thickness for strong bonding while reducing brittleness, enabling it to withstand thermal stress during cycling without cracking.
3Reliability
If a crystalline active metal compound layer is formed instead of an amorphous layer, then resistance to cracking under ultrasonic waves is improved, but the formation process becomes more complex
Solution Approach 1:
The patent employs a self-organizing mechanism where the active metal compound layer automatically forms a crystalline structure through controlled diffusion and reaction during the brazing process. The system utilizes thermal energy and chemical potential gradients to drive the phase transformation, eliminating the need for external crystallization equipment or complex multi-step processing.
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 crystalline active metal compound layer effectively prevents peeling between ceramic and copper members during ultrasonic joining and enhances thermal cycle reliability by managing thermal stress, while maintaining a balance to avoid excessive brittleness.
Implementation Method 1
a crystalline active metal compound layer formed of a compound including an active metal is formed on a ceramic member side
Implementation Method 2
it is possible to suppress peeling of the ceramic member and the copper member even in a case where ultrasonic waves are applied thereto
Data Source
AI summary
A bonded body is formed to configured to join a ceramic member formed of a Si-based ceramic and a copper member formed of copper or a copper alloy, in which, in a joint layer formed between the ceramic member and the copper member, a crystalline active metal compound layer formed of a compound including an active metal is formed on the ceramic member side.