Active Metal Brazing Substrate with Low-Silver Bonding Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional direct-bonding-copper (DBC) ceramic substrates face issues with high thermal stress due to thermal expansion coefficient differences, leading to copper peeling off from ceramic substrates, and high silver content in active metal brazing materials results in high costs and electro-migration problems.
Innovation Solution
An active metal brazing substrate material with a first brazing layer containing silver, copper, and a first active metal element, and a second brazing layer containing aluminum, copper, and a second active metal element, where the silver content is reduced and the brazing temperature is lowered below 900°C, using a high-temperature vacuum sintering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional direct-bonding-copper (DBC) ceramic substrates are used, then the structure is simple and manufacturing is easy, but thermal stress causes copper layer to peel off from ceramic substrate
Solution Approach 1:
The patent introduces a multi-layer composite structure consisting of ceramic substrate, active metal layer (with Ti, Zr, Ta, Nb, V, or Hf), and copper layer. This composite structure resolves the peeling issue by creating intermediate bonding layers that accommodate thermal expansion differences while maintaining strong adhesion between copper and ceramic substrate.
Solution Approach 2:
The active metal layer serves as an intermediary between the copper layer and ceramic substrate. These active metals (Ti, Zr, Ta, Nb, V, Hf) create strong chemical bonds with both the ceramic substrate and copper, acting as a mediator that prevents direct copper-ceramic bonding failures due to thermal stress.
2Temperature
If conventional active metal brazing paste material with high silver content is used, then brazing temperature can be maintained, but material cost and manufacturing cost increase significantly
Solution Approach 1:
The patent changes the compositional parameters of the brazing paste by reducing silver content from conventional high levels (often >70 wt%) to optimized lower levels (30-60 wt%), while adjusting copper and active metal content accordingly. This parameter change maintains brazing temperature capability while significantly reducing material cost.
Solution Approach 2:
The patent applies different material compositions to different functional layers: the active metal layer contains specific active metals for bonding, while the copper layer provides electrical conductivity. This local quality differentiation allows optimization of each layer's function while reducing overall silver content and cost.
3Ease of manufacture
If conventional active metal brazing paste material with high silver content is used, then brazing can be performed, but electro-migration issues occur due to silver residue after etching
Solution Approach 1:
The patent extracts or removes silver from the active metal layer composition, eliminating the source of electro-migration problems. By using alternative active metals (Ti, Zr, Ta, Nb, V, Hf) without silver in the bonding layer, the process maintains brazing capability while eliminating harmful electro-migration effects from silver residue.
4Strength
If brazing temperature is kept high to ensure bonding strength, then connection strength is improved, but material cost and impact on metal properties increase
Solution Approach 1:
The patent optimizes the brazing temperature parameter to a range of 700-900°C, which is lower than conventional high-temperature brazing. Combined with optimized paste composition (reduced silver, adjusted copper and active metal ratios), this temperature parameter change achieves strong bonding while reducing material cost and thermal impact on metal properties.
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 solution effectively reduces material and manufacturing costs, improves bonding strength, and mitigates electro-migration issues while maintaining high-temperature performance.
Implementation Method 1
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 2
performing a high-temperature vacuum sintering process to braze the copper layer to the ceramic substrate through the active metal layer
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, which includes aluminum (Al), copper (Cu), and a second active metal element, but does not contain silver. Based on a total weight of the second metal composite material being 100 parts by weight, an aluminum content is not less than 40 parts by weight.