Metal-Ceramic Substrate Contact Structure for Thermal Shock Resistance
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Solution Overview
Problem
Metal-ceramic substrates experience peeling due to different thermal expansion coefficients of metal and ceramic materials under extreme temperature changes, leading to reduced thermal shock resistance, which is crucial for power electronics applications.
Innovation Solution
A metal-ceramic substrate design with a structuring region in the metal layer having a specific geometry, where the ratio of solid material to total area exceeds 70%, and the solid material adjacent to the upper half of the contour line has a higher silver content, enhancing bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer is bonded to a ceramic body using conventional methods, then the metal layer provides electrical conductivity and bonding, but the metal layer peels off from the ceramic body under extreme temperature changes due to different thermal expansion coefficients
Solution Approach 1:
The metal layer is divided into multiple discrete metal islands separated by gaps, rather than forming a continuous layer. This segmentation reduces the overall thermal stress accumulated in the metal layer during temperature cycling, preventing peeling while maintaining necessary electrical and thermal functions through the distributed metal regions.
Solution Approach 2:
The metal layer features non-uniform local properties with varying silver content distributed across different regions. Areas with higher silver content provide enhanced bonding strength and ductility where stress concentration occurs, while other regions maintain appropriate electrical conductivity. This local variation in material composition allows the structure to accommodate thermal expansion differences without peeling.
2Reliability
If the metal layer is made continuous to ensure electrical conductivity, then electrical performance is improved, but thermal shock resistance deteriorates due to uniform stress distribution across the entire metal layer
Solution Approach 1:
The continuous metal layer is replaced by multiple discrete metal islands that are spatially distributed across the ceramic surface. While each island is electrically isolated, the collective arrangement provides sufficient electrical conductivity for the application while allowing stress to be distributed and released at the gaps between islands, thereby improving thermal shock resistance.
Solution Approach 2:
The silver content is varied across different regions of the metal layer structure. By adjusting the concentration of silver in specific areas, the invention optimizes both electrical conductivity and mechanical bonding properties locally, enabling the structure to maintain electrical performance while resisting thermal shock through controlled material composition variations.
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 design significantly improves thermal shock resistance by preventing the metal layer from detaching from the ceramic body, maintaining structural integrity under temperature fluctuations.
Implementation Method 1
the copper compound melts and wets the surface of the ceramic body
Implementation Method 2
the copper compound melts and wets the surface of the ceramic body
Implementation Method 3
The role of the active metal is to react with the ceramic material, thus enabling the ceramic material to bond to the remaining solder to form a reaction layer
Implementation Method 4
Due to the different thermal expansion coefficients of the metal and the ceramic, repeated temperature changes can lead to the metal layer peeling off from the ceramic body
Data Source
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AI summary
The invention relates to a metal-ceramic substrate and an electronic component comprising a metal-ceramic substrate.The metal-ceramic substrate comprises: a) a ceramic body having a main boundary surface, b) a metal layer having a main boundary surface, wherein the metal layer is bonded to the ceramic body in a planar manner, and wherein the metal layer has a structuring region which comprises (i) solid material in some regions and (ii) non-solid material in some regions, and c) a contact region arranged on the metal layer comprising silver, characterized in that in a cross-section through the metal-ceramic substrate perpendicular to the main boundary surface of the ceramic body, the structuring region has a geometry wherein the following requirement is met: ABCDsolid/ABCDtotal>70%, where A (BCDtotal) stands for the total area of the triangle described by the points B, C and D, and A (BCDsolid) stands for the area of the triangle described by the points B, C and D that is occupied by solid material.The solid material has an increased silver content in the area adjacent to the upper half of a contour line.