Metal-Ceramic Substrate Bond Layer for Stable Conductivity
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Solution Overview
Problem
Existing metal-ceramic substrates face challenges in achieving high stability and thermal/electrical conductivity while avoiding silver migration and the limitations of high-temperature processing, particularly due to the diffusion of low-melting metals into the metal layer, which degrades conductivity.
Innovation Solution
A metal-ceramic substrate with a bonding layer comprising metals M1 (melting point ≥700°C), M2 (melting point <700°C), M3 (active metals), and M4 (bismuth, gallium, zinc, indium, germanium, aluminum, or magnesium), where M2's content is optimized between 10-20% by weight and M4's content is minimized to maintain stability and conductivity, and silver content is limited to prevent migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of low-melting-point metal M2 in the bonding layer is increased to improve bond stability, then the bond stability between metal layer and ceramic body increases, but the thermal and electrical conductivity of the metal-ceramic substrate decreases due to diffusion of M2 into the metal layer
Solution Approach 1:
The patent applies parameter changes by precisely controlling the content of low-melting-point metal M2 within 10-20 wt% and limiting metal M4 to 0.01-2 wt%. This optimization resolves the contradiction by finding the optimal concentration range that provides sufficient bond stability while minimizing diffusion into the metal layer, thereby maintaining thermal and electrical conductivity.
Solution Approach 2:
The patent uses composite materials by creating a multi-metal bonding layer containing metals M1, M2, M3, and M4 with specific melting points and properties. This composite structure allows the bonding layer to simultaneously achieve stable bonding (through M2 and M4) and maintain conductivity (through controlled composition that limits diffusion), resolving the contradiction between bond stability and conductivity.
2Reliability
If silver is used in the bonding layer to achieve stable bonding, then bond stability improves, but silver migration problems occur
Solution Approach 1:
The patent applies the taking out principle by removing silver from the bonding layer composition entirely. The bonding layer now consists of metals M1, M2, M3, and M4 without silver, which eliminates the source of silver migration problems while maintaining bond stability through the alternative metal combination and controlled composition ranges.
3Reliability
If high-temperature processing is used to achieve stable bonding, then bond stability improves, but the process temperature must be slightly below the melting point of copper which limits applicability
Solution Approach 1:
The patent applies parameter changes by utilizing metals with different melting points (M1 ≥700°C, M2 <700°C) in the bonding layer. This allows processing at temperatures that are high enough to ensure stable bonding but below the melting point of copper, thereby resolving the contradiction between achieving stable bonding and avoiding excessive temperature requirements.
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 achieves a stable connection between the metal and ceramic layers with high thermal and electrical conductivity, reducing silver migration issues and maintaining conductivity by optimizing the metal composition within specific weight ranges.
Implementation Method 1
the copper compound melts and wets the surface of the ceramic body, resulting in a stable, metallurgical bond between the copper foil and the ceramic body
Implementation Method 2
an increasing content of low-melting-point metal in the bonding layer leads to increased diffusion of the low-melting-point metal into the metal layer of the metal-ceramic substrate
Implementation Method 3
ensure the rapid dissipation of large amounts of heat during operation
Implementation Method 4
ensure the rapid dissipation of large amounts of heat during operation
Data Source
Figure 1
AI summary
The invention relates to a metal-ceramic substrate. One objective is to provide a metal-ceramic substrate that exhibits a highly stable bond between the metal layer and the ceramic body, as well as high thermal and electrical conductivity.The metal-ceramic substrate comprises (a) a ceramic body, (b) a metal layer, and (c) a compound layer located between the ceramic body and the metal layer, wherein the compound layer comprises (i) a metal M1 with a melting point of at least 700°C, (ii) a metal M2 with a melting point of less than 700°C, (iii) a metal M3 selected from the group of active metals, and (iv) a metal M4 selected from the group consisting of bismuth, gallium, zinc, indium, germanium, aluminum, and magnesium, wherein the compound layer has the following characteristics: (c1) M(M2)EDX = 10–20 wt%, (c2) 15 wt% ≤ [M(M4)/M(M2)]ICP * 1000 wt% + M(M2)EDX ≤ 100 wt%, and (c3) M(Ag)EDX < 10 wt%. Metal M3 is selected from the group consisting of hafnium, titanium, zirconium, niobium, tantalum, vanadium, and cerium. Metal M1 is copper. Metal M2 is tin.