Dual-Phase Intermetallic Structure for SiC Power Modules
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Solution Overview
Problem
Silicon carbide power modules face reliability issues due to high junction temperatures exceeding the melting point of traditional lead-free solders, leading to creep effects and void formation during solid-liquid inter-diffusion processes, which compromise mechanical strength and long-term reliability.
Innovation Solution
A dual-phase intermetallic interconnection structure is developed, comprising a first intermetallic phase and a second intermetallic phase with different high melting temperature metals, where the first intermetallic phase fills microvoids created during the formation of the second intermetallic phase, enhancing mechanical strength and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If solid-liquid inter-diffusion is used to form intermetallic compound, then melting temperature increases to over 300°C, but voids are formed due to volume decrease during the process
Solution Approach 1:
The patent employs a composite intermetallic compound structure consisting of two different intermetallic compounds formed from different high melting temperature metals. This composite structure allows the first intermetallic compound to fill the voids created during formation of the second intermetallic compound, thereby maintaining high melting temperature while eliminating harmful voids that compromise reliability
Solution Approach 2:
The patent converts the harmful volume decrease during intermetallic compound formation into a beneficial process by intentionally creating a two-phase structure where the first intermetallic compound fills the voids. The volume contraction that would normally create defects is instead utilized to create a dense, void-free composite structure where one intermetallic phase fills the spaces created by the formation of another phase
2Temperature
If high temperature lead-free solders are used, then junction temperature can reach 250°C, but creep effect occurs reducing mechanical strength
Solution Approach 1:
The patent uses a composite structure of two different intermetallic compounds with distinct properties. The combination of different high melting temperature metals creates a material system where the two phases complement each other, providing both high temperature stability and enhanced mechanical strength to resist creep effects at junction temperatures up to 250°C
3Reliability
If solid-liquid inter-diffusion is used, then long-term reliability is improved, but fabrication time exceeds 10 minutes and junction temperature exceeds 260°C
Solution Approach 1:
The patent optimizes the formation parameters of the two-phase intermetallic compound structure, including temperature, time, and thickness parameters. By carefully controlling these parameters, the patent achieves complete reaction and stable intermetallic compound formation within acceptable time limits while maintaining junction temperature within safe operating ranges, thus improving reliability without excessive time or temperature penalties
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-phase intermetallic interconnection structure improves mechanical strength and thermal conductivity, reducing void formation and increasing the lifespan of power modules by embedding the first intermetallic phase into the second intermetallic phase, thus addressing the reliability concerns at high temperatures.
Implementation Method 1
the metal of the outer metal layers and the metal of the inner metal layer form a first intermetallic phase
Implementation Method 2
heated to melt the outer metal layers
Implementation Method 3
the metal of the outer metal layers and the metal of the first solder metal layer and the second solder metal layer form a second intermetallic phase
Implementation Method 4
heated to melt the outer metal layers
Implementation Method 5
the first intermetallic phase is used to fill the micropore defects created as a result of a decrease in volume during the formation of the second intermetallic phase
Data Source
AI summary
Provided are a dual-phase intermetallic interconnection structure and a fabricating method thereof. The dual-phase intermetallic interconnection structure includes a first intermetallic compound, a second intermetallic compound, a first solder layer, and a second solder layer. The second intermetallic compound covers and surrounds the first intermetallic compound. The first intermetallic compound and the second intermetallic compound contain different high-melting point metal. The first solder layer and the second solder layer are disposed at the opposite sides of the second intermetallic compound, respectively. The first intermetallic compound is adapted to fill the micropore defects generated during the formation of the second intermetallic compound.