Sn-Sb Solder Alloy Composition for Thermal Cycle Bond Reliability
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Solution Overview
Problem
Conventional solder alloys, despite additions like Te, Ag, Cu, Fe, and Ni, exhibit insufficient bonding reliability for temperature cycle tests beyond 500 cycles, particularly in applications requiring endurance through 1000 cycles or more.
Innovation Solution
A solder alloy with Sb content between 3 wt% to 30 wt%, Te between 0.01 wt% to 1.5 wt%, Au between 0.005 wt% to 1 wt%, and at least one of Ag and Cu, where Ag and Cu are in specific ranges to form intermetallic compounds, enhancing crack resistance and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Te is added to Sn to improve elongation, then high-temperature elongation is enhanced, but the bonding reliability remains insufficient for long-duration temperature cycling
Solution Approach 1:
The patent merges Te addition with Sb, Au, Ag, and Cu to create a multi-element alloy system. This combination resolves the contradiction by complementing Te's elongation-enhancing effect with Sb's strength contribution, Au's high-temperature stability, and Ag/Cu's intermetallic compound formation, achieving both improved elongation and reliable bonding for 1000+ temperature cycles.
Solution Approach 2:
The patent optimizes the Te content parameter within a specific range (0.01-1.5 mass%) and combines it with controlled amounts of other elements. This parameter optimization resolves the contradiction by preventing Te from causing excessive brittleness while maintaining its elongation benefits, achieving balanced performance for both elongation and bonding reliability.
2Strength
If Ag and Cu are added to form intermetallic compounds, then bonding strength is improved, but the alloy composition becomes more complex
Solution Approach 1:
The patent specifies precise compositional ranges for Ag (0.1-20 mass%) and Cu (0.05-5 mass%) to control intermetallic compound formation. This parameter control resolves the contradiction by achieving sufficient bonding strength through optimized intermetallic formation while maintaining manufacturability and avoiding excessive composition complexity.
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 solder alloy significantly improves high-temperature elongation and crack resistance, ensuring high reliability in bonded structures by absorbing repetitive stress during heat cycles and maintaining bonding strength across multiple temperature cycles.
Implementation Method 1
Te which is solidly dissolved in Sn
Implementation Method 2
Au having different ionic radius at high temperature is complicatedly substituted with Te which is solidly dissolved in Sn so as to cause dislocation
Implementation Method 3
an intermetallic compound of Ag and Sn, or Cu and Sn is precipitated
Implementation Method 4
an intermetallic compound of Ag and Sn, or Cu and Sn is precipitated, the bonding strength is improved
Implementation Method 5
it is possible to absorb the repetitive stress generated during the heat cycle
Data Source
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AI summary
A solder alloy of the disclosure includes Sb of which a content is in a range of 3 wt% to 30 wt%, Te of which a content is in a range of 0.01 wt% to 1.5 wt%, Au of which a content is in a range of 0.005 wt% to 1 wt%, at least one of Ag and Cu, wherein a content rate of at least one of Ag and Cu in the solder alloy is in a range of 0.1 wt% to 20 wt%; and a content rate of a sum of Ag and Cu in the solder alloy is in a range of 0.1 wt% to 20 wt%;, and a balance of Sn.