Dual-Layer Active Metal Brazing Substrate for Lower-Temperature Bonding
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Solution Overview
Problem
Conventional direct-bonding-copper (DBC) ceramic substrates face issues with thermal stress and high manufacturing costs due to the use of silver-rich active metal brazing paste materials, which also lead to electro-migration problems during the etching process.
Innovation Solution
An active metal brazing substrate material with a dual-layer structure, comprising a first brazing layer with a high silver content and a second brazing layer with a low melting point metal, reducing silver usage and brazing temperature below 900°C, and eliminating silver from the second layer to lower costs and prevent electro-migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silver-rich active metal brazing paste material is used, then bonding strength is improved, but material cost and manufacturing cost increase
Solution Approach 1:
The brazing paste is divided into multiple layers with different compositions. The first brazing layer contains silver-copper-titanium for strong bonding, while the second brazing layer uses low-melting-point metal-copper-titanium without silver, reducing overall silver content and cost while maintaining bonding performance.
Solution Approach 2:
Different regions of the brazing structure have different material compositions optimized for their specific functions. The first brazing layer near the ceramic substrate has high silver content for maximum bonding strength, while the second brazing layer has reduced or no silver for cost reduction, creating a gradient of material quality.
2Strength
If high brazing temperature is used, then bonding strength is improved, but impact on metal properties and energy consumption increase
Solution Approach 1:
The invention changes the compositional parameters of the brazing paste by introducing low-melting-point metals (such as tin, zinc, or aluminum) in the second brazing layer, which lowers the overall melting and brazing temperature while maintaining adequate bonding strength through the combined action of both layers.
3Strength
If silver content is increased, then bonding strength is improved, but electro-migration problems occur during etching process
Solution Approach 1:
Silver is extracted or removed from the second brazing layer, which is not in direct contact with the ceramic substrate. This reduces the total silver content and minimizes electro-migration issues during etching, while the first brazing layer retains sufficient silver for strong bonding at the critical interface.
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 dual-layer structure enhances bonding strength, reduces material and manufacturing costs, and mitigates electro-migration issues, while allowing for lower brazing temperatures, thus improving the thermal and electrical properties of the ceramic substrates.
Implementation Method 1
A melting point of the low melting point metal element is between 130° C. and 350° C.
Implementation Method 2
Active metal elements (e.g., Ti, Zr, Ta, Nb, V, or Hf) of the active metal brazing substrate materials can wet a side surface of a ceramic substrate, so as to braze an ultra-thick copper foil onto the ceramic substrate at a high temperature.
Implementation Method 3
a brazing layer formed between the ultra-thick copper foil and the ceramic substrate through the active metal brazing process has a high connection strength
Data Source
AI summary
An active metal brazing substrate material and a method for producing the same are provided. The active metal brazing substrate material includes a ceramic substrate layer, a first brazing layer, a second brazing layer, and a conductive metal layer that are sequentially stacked. The first brazing layer includes a first metal composite material, which includes silver (Ag), copper (Cu), and a first active metal element. Based on a total weight of the first metal composite material being 100 parts by weight, a silver content is not less than 50 parts by weight. The second brazing layer includes a second metal composite material. The second metal composite material includes a low melting point metal element (e.g., Sn), copper (Cu), and a second active metal element, but does not include silver. A melting point of the low melting metal element is between 130° C. and 350° C.