Copper-Clad Ceramic Substrate Hardness Gradient Against Peeling
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Solution Overview
Problem
Semiconductor device substrates face durability issues under hot-cold cycles, particularly in the form of copper plate peeling due to thermal expansion differences.
Innovation Solution
A semiconductor device substrate design with copper plates having a hardness gradient along the thickness direction, specifically with nanoindentation hardness decreasing from the interface to a distance of 100 µm, ensuring the copper plates are bonded effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copper plate is bonded to a ceramic substrate using a bonding agent, then the substrate can be assembled with electrical connections, but the copper plate peels off under hot-cold cycle conditions
Solution Approach 1:
The invention changes the physical parameter of the copper plate by creating a hardness gradient through controlled copper grain growth. The copper plate is designed with higher hardness near the bonding interface and lower hardness toward the opposite surface, achieved by controlling grain size distribution. This parameter change allows the copper plate to better accommodate thermal expansion stresses during hot-cold cycles while maintaining strong bonding at the interface.
Solution Approach 2:
The invention applies local quality by creating non-uniform hardness distribution within the copper plate. The region near the bonding interface has different properties (higher hardness, smaller grain size) compared to the region farther from the interface (lower hardness, larger grain size). This local differentiation allows the copper plate to provide both strong bonding at the interface and stress relief in the bulk material during thermal cycling.
2Stability of the object's composition
If the copper plate thickness is increased to improve structural stability, then the substrate becomes more robust, but the bonding interface becomes more prone to peeling under thermal stress
Solution Approach 1:
The invention changes the hardness parameter distribution through controlled grain growth in the copper plate. By creating a gradient where hardness decreases from the bonding interface toward the opposite surface, the thicker copper plate can accommodate thermal expansion stresses without peeling, while still providing structural stability. The specific grain size control ensures optimal balance between bonding strength and stress resistance.
3Ease of manufacture
If the copper plate is made with uniform hardness throughout, then the manufacturing process is simpler, but the bonding interface peels under thermal expansion stress
Solution Approach 1:
The invention implements parameter changes by controlling copper grain growth to create a hardness gradient. This is achieved through controlled cooling rates and heat treatment processes that are relatively simple to implement in existing manufacturing lines. The grain size control mechanism uses standard metallurgical techniques to create the desired hardness distribution without requiring complex additional processing steps.
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 substrate exhibits enhanced hot-cold cycle durability by suppressing copper plate peeling, maintaining structural integrity under temperature fluctuations.
Implementation Method 1
each of the copper plates includes a region where hardness decreases along a thickness direction of the copper plate between a position separated from an interface between a corresponding one of the bonding layers and the copper plate by 100 μm in the thickness direction and the interface
Implementation Method 2
brazing material layers respectively disposed on the first surface and the second surface
Data Source
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AI summary
A semiconductor device substrate according to the present invention includes a silicon nitride ceramic substrate having a first surface and a second surface, brazing material layers respectively disposed on the first surface and the second surface, and copper plates respectively disposed on the bonding layers, including a region where hardness decreases along a thickness direction of each copper plate from an interface between a corresponding one of the bonding layers and the copper plate and the interface.