Grain Size Gradient Copper Layers for Thermal-Shock Resistance
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Solution Overview
Problem
Existing methods for producing metal-ceramic substrates do not effectively optimize the grain size of copper layers for improved thermal-shock resistance and processing compatibility, leading to potential delamination and crack formation during temperature changes.
Innovation Solution
A method involving different temperature treatments before joining copper layers to induce grain growth, allowing for controlled adjustment of grain sizes in the final product, where one layer is finer-grained and the other coarser-grained, optimizing their bonding to a ceramic layer for enhanced thermal-shock resistance and processing compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copper layer with larger grain size is used to improve thermal-shock resistance, then the probability of delamination or crack formation is reduced, but the suitability for further processing with electrical or electro-optical systems and bonding of components deteriorates
Solution Approach 1:
The copper metallization is divided into multiple layers with different grain sizes. The first copper layer (facing the ceramic) has a larger grain size for thermal-shock resistance, while the second copper layer (outer surface) has a finer grain size for processing compatibility. This segmentation allows each layer to optimize for its specific function.
Solution Approach 2:
Different regions of the copper metallization are given different grain sizes according to their functional requirements. The region in contact with the ceramic substrate has coarse grains for mechanical stability, while the exposed outer surface has fine grains for bonding and processing. This local differentiation resolves the contradiction between bulk reliability and surface manufacturability.
2Ease of manufacture
If a copper layer with finer grain size is used to improve processing compatibility and bonding suitability, then the ease of manufacture is improved, but the thermal-shock resistance deteriorates
Solution Approach 1:
The copper metallization is divided into multiple layers with different grain sizes. The first copper layer (facing the ceramic) has a larger grain size for thermal-shock resistance, while the second copper layer (outer surface) has a finer grain size for processing compatibility. This segmentation allows each layer to optimize for its specific function.
Solution Approach 2:
Different regions of the copper metallization are given different grain sizes according to their functional requirements. The region in contact with the ceramic substrate has coarse grains for mechanical stability, while the exposed outer surface has fine grains for bonding and processing. This local differentiation resolves the contradiction between bulk reliability and surface manufacturability.
3Device complexity
If uniform grain size is used in the copper layer, then the manufacturing process is simpler, but the overall performance for both thermal-shock resistance and processing compatibility cannot be optimized
Solution Approach 1:
The copper metallization is divided into multiple layers with different grain sizes. The first copper layer (facing the ceramic) has a larger grain size for thermal-shock resistance, while the second copper layer (outer surface) has a finer grain size for processing compatibility. This segmentation allows each layer to optimize for its specific function.
Solution Approach 2:
Different regions of the copper metallization are given different grain sizes according to their functional requirements. The region in contact with the ceramic substrate has coarse grains for mechanical stability, while the exposed outer surface has fine grains for bonding and processing. This local differentiation resolves the contradiction between bulk reliability and surface manufacturability.
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 method enables improved thermal-shock resistance and easier processing by ensuring a controlled grain size gradient in the copper layers, reducing the risk of delamination and crack formation, while maintaining mechanical and electrical properties.
Implementation Method 1
a grain growth in the first metal layer and/or the second metal layer is initiated in such a way that in the produced semi-finished metal product, in particular in the produced metal-copper substrate, a first grain size in the first metal layer differs from a second grain size in the second metal layer
Data Source
AI summary
A method for producing a semi-finished metal product (2), in particular a semi-finished copper product, for a metal-copper substrate, in particular for a copper-ceramic substrate, including:providing a first metal layer (11), in particular a first copper layer, and a second metal layer (12), in particular a second copper layer,joining the first metal layer (11) and the second metal layer (12) to form the semi-finished metal product (2), wherein, chronologically before the first metal layer (11) is joined to the second metal layer (12) by means of different temperature treatments, a grain growth in the first metal layer (11) and/or the second metal layer (12) is initiated in such a way that in the produced semi-finished metal product (2), in particular in the produced metal-copper substrate, a first grain size in the first metal layer (11) differs from a second grain size in the second metal layer (12).