Active Metal Brazing Substrate With Low-Silver Bonding Strength
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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 with high silver content have high material costs and electromigration problems.
Innovation Solution
An active metal brazing substrate is developed with a ceramic substrate layer, an active metal layer formed from a solder paste containing silver, copper, and an active metal, and a conductive metal layer, where the silver content ranges from 10 wt% to 60 wt%, enhancing the connection force between 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:
An active metal layer is introduced as an intermediary between the copper layer and ceramic substrate. This active metal layer contains elements that react with both copper and ceramic, forming strong chemical bonds at both interfaces, thereby preventing copper peeling while maintaining manufacturing feasibility through a coating process.
Solution Approach 2:
The bonding structure transitions from a simple copper-ceramic interface to a composite structure with multiple layers including copper, active metal, and ceramic. The active metal layer acts as a transition zone with intermediate thermal expansion properties, reducing thermal stress concentration and improving bonding reliability.
2Reliability
If high silver content is used in active metal brazing substrate, then brazing performance is improved, but material cost increases and electromigration problems occur
Solution Approach 1:
The silver content parameter in the active metal layer is optimized to a specific range (10-60 wt%) rather than using high silver content. This parameter optimization maintains adequate brazing performance and reliability while significantly reducing material cost and minimizing electromigration issues associated with excessive silver.
Solution Approach 2:
Instead of uniformly distributing high silver content throughout the active metal layer, the invention uses a controlled composition where silver is present at optimal levels combined with other active metal elements. This localized optimization of material composition achieves effective brazing without the drawbacks of high silver content.
3Quantity of substance
If silver content is reduced in active metal brazing substrate, then material cost decreases and electromigration is reduced, but connection force between layers may be compromised
Solution Approach 1:
The active metal layer is formulated as a composite material containing silver combined with other active metal elements. This composite composition provides adequate connection force through synergistic effects of different metal elements, maintaining bonding strength while reducing overall silver content for cost and reliability benefits.
Solution Approach 2:
The composition parameters of the active metal layer are optimized to find the optimal silver content range (10-60 wt%). Within this range, the connection force is maintained at acceptable levels while achieving reduction in material cost and electromigration. The specific composition is tuned to balance strength requirements with material efficiency.
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 active metal brazing substrate achieves a tensile strength of 165 N/cm to 270 N/cm, addressing the thermal stress and electromigration issues while reducing material costs, and is suitable for high-temperature and high-power applications.
Implementation Method 1
coating an active metal solder paste onto a ceramic substrate so as to form an active metal layer on the ceramic substrate
Implementation Method 2
disposing a conductive metal layer onto the active metal layer and then implementing a brazing process to obtain an active metal brazing substrate
Data Source
AI summary
An active metal brazing substrate and a method for manufacturing the same are provided. The active metal brazing substrate includes a ceramic substrate layer, an active metal layer, and a conductive metal layer. The active metal layer is disposed between the ceramic substrate layer and the conductive metal layer. The active metal layer is formed from an active metal solder and an organic dispersion medium. The active metal solder includes silver, copper, and an active metal. Based on a total weight of the active metal solder being 100 wt %, an amount of the silver ranges from 10 wt % to 60 wt %. A tensile strength of the active metal brazing substrate ranges from 165 N/cm to 270 N/cm.