Sn-Cu-Ni Metal Particle Joints for High-Temperature Reliability
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Solution Overview
Problem
Next-generation power semiconductors using SiC and GaN require joint materials with high heat resistance and reliability, but existing materials fail to meet these demands due to thermal expansion differences, leading to breakage and fracture, and existing SnAgCu-based materials are only suitable for temperatures up to 125°C.
Innovation Solution
A metal particle with a specific intermetallic compound composition of Sn, Cu, and Ni, forming an endotaxial joint, which retains a high-temperature phase crystal structure even at room temperature, suppressing volumetric changes and enabling reliable joining of components with different thermal expansion coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an SnAgCu-based joint material is used for power semiconductor, then the material is easy to manufacture and process, but the heat resistance is limited to approximately 125°C and cannot meet next-generation requirements
Solution Approach 1:
The invention changes the chemical composition parameters of the joint material by incorporating specific intermetallic compounds (such as Cu6Sn5, Cu3Sn, and Ni3Sn4) with controlled ratios of Sn, Cu, and Ni elements. This compositional parameter adjustment enables the material to maintain structural stability and mechanical properties at elevated temperatures up to 250°C, thereby achieving the required heat resistance while preserving joint reliability
Solution Approach 2:
The invention creates a composite joint material system consisting of multiple intermetallic compounds with complementary properties. The combination of Sn-Cu-Sn-Ni intermetallic phases forms a multi-phase composite structure that leverages the high-temperature stability of Ni-containing compounds while maintaining the excellent wetting and bonding characteristics of Sn-Cu systems, enabling reliable operation at next-generation power semiconductor temperatures
2Reliability
If devices and components with different coefficients of thermal expansion are joined, then the joint material must accommodate thermal stress, but this leads to breakage of devices, components, or fracture of the joint material
Solution Approach 1:
The invention applies local quality by creating a joint material with spatially varying composition and phase distribution. The intermetallic compound structure provides localized regions with different mechanical properties - softer phases accommodate thermal expansion differences while harder phases maintain structural integrity. This local property variation allows the joint to absorb thermal stress without fracture while maintaining overall strength
Solution Approach 2:
The joint material acts as an intermediary between devices and components with different thermal expansion coefficients. The multi-phase intermetallic compound structure serves as a buffer zone that mediates the thermal stress transfer, with its complex phase structure absorbing and distributing stress uniformly, preventing stress concentration that would lead to breakage of connected components
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 metal particle provides enhanced heat resistance and mechanical strength, maintaining joint integrity over a wide temperature range, effectively joining components with varying thermal expansion coefficients, outperforming prior art in both heat resistance and reliability.
Implementation Method 1
placement of the intermetallic compound in the shell, between a substrate and an object to be joined, contributes to suppress Cu and so forth from diffusing into the object to be joined
Implementation Method 2
Difference of coefficients of thermal expansion among the materials would, however, result in breakage of the devices and components, or fracture of a joint material at a joint area
Data Source
AI summary
According to this invention, provided is a metal particle that includes an intermetallic compound composed of Sn, Cu and Ni, in a basal phase that contains Sn and an Sn—Cu alloy, and at least parts of the Sn—Cu alloy and the intermetallic compound in the basal phase form an endotaxial joint.