Intermetallic Brazing Assembly for High-Temperature Semiconductor Joints
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Solution Overview
Problem
Current methods for assembling high-temperature semiconductor components, such as those using 'wide gap' materials, face challenges in achieving reliable and efficient soldering due to high melting temperature requirements and risks of damaging electronic circuits, as well as issues with electromigration and pressure-induced damage in existing brazing processes.
Innovation Solution
A brazing method involving the use of two brazing materials that form an intermetallic compound with a melting temperature higher than each individual material, allowing for a stable and efficient assembly at a relatively low temperature, achieved by heating and fusing the materials to create a 100% intermetallic compound, which is more stable and has a higher melting point than the individual materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal alloy with very high melting temperature is used to assemble the silicon carbide chip, then the operating reliability is improved, but the risk of damaging the electronic circuit increases
Solution Approach 1:
The invention changes the melting temperature parameter of the brazing material from very high (traditional high-temperature alloy) to moderate (eutectic alloy with melting point around 600-700°C), while achieving the same reliability goal through a different mechanism (intermetallic compound formation rather than high-temperature strength)
Solution Approach 2:
The invention utilizes phase transitions by heating the eutectic alloy to its melting point to create a liquid state that facilitates diffusion and intermetallic compound formation, then cooling to obtain a solid joint with high reliability. The phase change enables the brazing process to proceed at lower temperatures while achieving strong bonding
2Temperature
If a diffusion brazing process with two different alloys is used to precipitate an intermetallic compound, then the melting temperature requirement is met, but the implementation time and cost increase
Solution Approach 1:
The invention extracts and eliminates one of the two alloys from the traditional diffusion brazing process. Instead of using two different alloys (low melting point and high melting point), the invention uses only a eutectic alloy, simplifying the process while maintaining the ability to form intermetallic compounds at appropriate temperatures
Solution Approach 2:
The eutectic alloy is pre-formulated with specific composition ratios that enable it to automatically form the desired intermetallic compound structure during cooling. This preliminary preparation of the alloy composition eliminates the need for complex multi-step diffusion processes with multiple materials
3Temperature
If a diffusion brazing process with two different alloys is used to precipitate an intermetallic compound, then the melting temperature requirement is met, but the homogeneity of the seal is compromised
Solution Approach 1:
The invention uses a eutectic alloy with a specific homogeneous composition ratio that ensures uniform distribution of elements during melting and cooling. This homogeneous starting material prevents the segregation and heterogeneity problems that occur when using two different alloys with different compositions and melting behaviors
4Ease of manufacture
If silver powder is used for sintering, then the assembly is achieved, but electromigration causes electrical contacts between points at different potentials
Solution Approach 1:
The invention replaces silver (a precious metal prone to electromigration) with a eutectic alloy composition that forms a stable intermetallic compound structure. This substitution eliminates the electromigration problem while maintaining assembly capability, effectively using a more stable material replacement strategy
5Ease of manufacture
If sintering under pressure is used to assemble the component, then the assembly is achieved, but damage to the chips occurs
Solution Approach 1:
The invention replaces the mechanical pressure system (sintering under 5-40 MPa) with a thermal system (heating to melt the eutectic alloy). The liquid brazing material flows and bonds the components without requiring high mechanical pressure, thereby eliminating pressure-induced chip damage while achieving secure assembly
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
This method reduces implementation time and costs, ensures homogeneity of the assembly joint, and prevents damage to electronic components by maintaining a lower soldering temperature while achieving a stable joint capable of withstanding high operating temperatures.
Implementation Method 1
heating and fusing the two selected brazing materials to substantially reach the melting temperature of each of the selected brazing materials
Implementation Method 2
obtain the precipitation of an intermetallic compound
Implementation Method 3
wait in this molten state for the alloy at a higher melting temperature to diffuse little by little through the liquid to 'precipitate an intermetallic compound'
Data Source
Figure 1~3
AI summary
The invention especially relates to a brazing method (100) for assembling two elements, said method comprising the following steps: selecting (101) two brazing materials that can generate, when they are heated and melted, an intermetallic compound having a melting temperature which is higher than the melting temperature of each of the selected brazing materials taken individually; positioning (102) the two selected brazing materials between the two elements; and heating and melting (103) the two selected brazing materials in order to substantially reach the melting temperature of each of the selected brazing materials so as to achieve the precipitation of an intermetallic compound having a melting temperature which is higher than the melting temperature of each of the selected brazing materials taken individually. The invention also relates to a device comprising two elements assembled by means of said method.