Double-Brazed Metal-Ceramic Substrate for Stronger Copper Bonding
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Solution Overview
Problem
Conventional direct-bonding-copper ceramic substrates face issues with thermal stress due to differing thermal expansion coefficients, leading to copper peeling off, and active metal brazing substrates have high silver content causing high material costs and electromigration problems.
Innovation Solution
A metal-ceramic substrate with double brazing layers is introduced, comprising a ceramic substrate layer, an active metal layer with a first brazing layer made from a silver, copper, and first active metal solder, and a second brazing layer made from a copper and second active metal solder without silver, enhancing the connection force between the ceramic and conductive metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct-bonding-copper ceramic substrate is used, then manufacturing simplicity is maintained, but thermal stress causes copper layer to peel off due to difference in thermal expansion coefficients
Solution Approach 1:
The bonding structure is segmented into three distinct layers: copper layer, active metal brazing layer, and ceramic substrate layer. This segmentation allows each layer to perform its specific function - the copper layer provides electrical conductivity, the active metal brazing layer provides strong bonding, and the ceramic substrate provides structural support and heat dissipation.
Solution Approach 2:
The active metal brazing layer acts as an intermediary between the copper layer and the ceramic substrate layer. It mediates the thermal expansion difference between copper and ceramic, preventing direct bonding failures while enabling strong adhesion through controlled metallurgical bonding during the brazing process.
2Strength
If active metal brazing substrate materials with high silver content are used, then bonding strength is improved, but material costs increase and electromigration problems occur
Solution Approach 1:
The composition parameters of the active metal brazing layer are precisely controlled with silver content limited to 1-10 wt%, copper at 70-85 wt%, and active metal elements at 1-10 wt%. This parameter optimization maintains sufficient bonding strength while dramatically reducing silver content to minimize electromigration and reduce material costs.
Solution Approach 2:
The active metal brazing layer is designed as a composite material system combining multiple elements (silver, copper, and active metal elements like zinc or indium) in optimized proportions. This composite structure provides synergistic effects that achieve strong bonding at copper-ceramic interfaces while reducing reliance on high-silver formulations.
3Object-generated harmful factors
If silver content in solder layer is decreased, then material costs and electromigration risks are reduced, but bonding strength may be compromised
Solution Approach 1:
The composition parameters are optimized to contain silver at 1-10 wt% (dramatically lower than conventional 50-70 wt%), copper at 70-85 wt%, and active metal elements at 1-10 wt%. This compositional change reduces electromigration risk and material cost while maintaining bonding strength through the synergistic combination of copper and active metal elements.
Solution Approach 2:
The active metal brazing layer exhibits local quality optimization where copper provides the matrix structure and electrical conductivity, while dispersed active metal elements (zinc, indium, or their alloys) provide localized bonding enhancement at the copper-ceramic interface. This local optimization allows reduced overall silver content while maintaining bonding strength at critical interfaces.
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 double brazing layer structure improves the connection force between the ceramic and conductive metal layers, enabling the substrate to withstand high-temperature and high-power operations while reducing material costs and minimizing electromigration risks.
Implementation Method 1
The active metal layer includes a first brazing layer and a second brazing layer. The first brazing layer is formed from a first active metal solder... The second brazing layer is formed from a second active metal solder... implementing a brazing process
Data Source
AI summary
A metal-ceramic substrate having double brazing layers and a method for manufacturing the same are provided. The metal-ceramic substrate includes a ceramic substrate layer, a conductive metal layer, and an active metal layer disposed between the ceramic substrate layer and the conductive metal layer. The active metal layer includes a first brazing layer formed from a first active metal solder and an organic dispersion medium, and a second brazing layer formed from a second active metal solder and another organic dispersion medium. The first active metal solder includes silver, copper, and a first active metal. Based on a total weight of the first active metal solder being 100 wt %, an amount of the silver ranges from 10 wt % to 60 wt %. The second active metal solder includes copper and a second active metal, but is without silver.