Transient Liquid Phase Bonding for Homogeneous Cu3Sn Power Electronics
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Solution Overview
Problem
Transient liquid phase bonding in power electronics often results in non-homogeneous bondlines due to multiple compound formation, leading to non-uniformity, inconsistency, and unpredictability, which complicates production and reliability, especially under high temperature operations.
Innovation Solution
A method that utilizes transient liquid phase bonding to convert non-homogeneous bondlines into homogeneous ones by consuming remaining mother materials and alloys through heat exposure during operation, ensuring a consistent and reliable bondline, particularly achieving a bondline made of Cu3Sn for improved electrical conductivity and stress relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If transient liquid phase bonding is used to join power electronics components, then bonding strength and electrical conductivity are improved, but the bondline becomes non-homogeneous due to multiple compound formation
Solution Approach 1:
The patent controls the bonding temperature parameter to be within a specific range (above the melting point of the low-melting-point material but below the formation temperature of unwanted intermetallic compounds). This parameter control prevents the formation of multiple compounds while maintaining strong bonding, thus resolving the contradiction between bonding strength and bondline homogeneity
Solution Approach 2:
The patent utilizes the phase transition (melting) of the low-melting-point bonding material to enable liquid-phase bonding. By controlling the temperature to melt only the bonding material and not form unwanted compounds, the process achieves both strong bonding and homogeneous bondline structure
2Adaptability or versatility
If multiple alloys are formed in the bondline, then bonding flexibility and material selection are improved, but production consistency and reliability deteriorate
Solution Approach 1:
The patent specifies precise temperature ranges for the bonding process that allow flexibility in material selection while ensuring consistent results. By controlling the temperature to prevent unwanted compound formation, the process maintains production consistency regardless of the specific materials used
Solution Approach 2:
The patent converts the potential harm of multiple compound formation into a benefit by using the controlled formation of specific intermetallic compounds (like Cu6Sn5) as desirable bonding phases. By controlling the process to form only these beneficial compounds and preventing unwanted ones, material flexibility is maintained while production consistency is improved
3Ease of manufacture
If conventional fabrication techniques are used for bonding, then manufacturing simplicity is maintained, but bondline uniformity and device reliability are compromised
Solution Approach 1:
The patent introduces specific temperature parameter control within conventional fabrication processes. By maintaining the bonding temperature within the specified range, the process achieves both the simplicity of conventional fabrication and the uniformity of controlled bonding, resolving the contradiction between ease of manufacture and manufacturing precision
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 approach enhances bonding quality and reliability by creating a uniform, conductive, and stress-resistant bondline with reduced dependency on pre-fabrication conditions, suitable for high-temperature power electronics applications, and compatible with conventional fabrication techniques.
Implementation Method 1
a first intermetallic compound layer is formed at the bonding interface by solid-state diffusion
Implementation Method 2
the non-homogeneous bondline is converted to a homogenous bondline through consumption of the remainder first mother material and the second alloy... exposure to heat, such as heat produced through operation of an electronic device
Data Source
AI summary
Alloy formation systems and methods and a mechanism, strategy and design for power electronics having high operating temperatures. The system creates a bondline targeted for performance in power electronics. The system provides for sequential alloy growth in high temperature operating power electronics. The system is at least applicable to wafer-to-wafer, die-to-wafer, die-to-substrate, or die-to-die bonding.