Al Wiring Alloy Composition for High-Temperature Reliability
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Solution Overview
Problem
Aluminum wiring materials used in industrial and semiconductor devices face challenges in maintaining high-temperature reliability and workability due to increased cold strength, which can lead to deformation, cracks, and disconnection, especially in high-temperature environments common in automotive and power semiconductor applications.
Innovation Solution
An Al wiring material containing Er, Yb, and/or Gd, along with Sc and Zr, Si, Fe, Ni, Ce, Y, and Zn, within specific concentration ranges, to enhance high-temperature reliability while suppressing cold strength increases, allowing for low-temperature or short-time heat treatments that improve productivity and maintain strength during high-temperature use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high purity Al is used as wiring material, then electrical conductivity is improved, but strength decreases in high-temperature environment
Solution Approach 1:
The patent uses Al-Si-Fe intermetallic compounds dispersed in an Al matrix to create a composite material structure. The intermetallic compounds (Al5SiFe, Al13Fe4, Al3Fe) act as reinforcement phases that maintain strength at high temperatures while the Al matrix provides electrical conductivity and ductility.
Solution Approach 2:
The patent controls the Si and Fe content within specific ranges (Si: 0.01-3.0 wt%, Fe: 0.01-1.0 wt%) to optimize the formation of heat-resistant intermetallic compounds. By controlling the concentration parameters of alloying elements, the material achieves both high-temperature strength and electrical conductivity.
2Reliability
If strength of wiring material is increased by adding elements, then high-temperature reliability is improved, but workability and bondability deteriorate
Solution Approach 1:
The patent precisely controls the Si and Fe content within narrow ranges (Si: 0.01-3.0 wt%, Fe: 0.01-1.0 wt%) to form heat-resistant intermetallic compounds without excessive strengthening. This parameter control ensures the material maintains adequate ductility and bondability while achieving high-temperature reliability.
Solution Approach 2:
The heat-resistant intermetallic compounds are distributed locally within the Al matrix, providing strength enhancement only where needed for high-temperature reliability, while the bulk Al matrix retains its inherent workability and bondability characteristics.
3Strength
If Sc is added to Al for precipitation hardening, then mechanical strength is improved, but material cost increases
Solution Approach 1:
The patent replaces expensive Sc with cheaper Si and Fe elements that can achieve similar or better heat-resistant properties through intermetallic compound formation. Si and Fe are abundant, low-cost elements that provide the same functional benefit of strength enhancement without the high material cost of Sc.
Solution Approach 2:
The patent creates Al-Si-Fe intermetallic compounds that provide precipitation hardening effects similar to Sc-based alloys, but using inexpensive Si and Fe elements. The composite structure of Al matrix with Si-Fe intermetallic phases achieves mechanical strength without the high cost of Sc addition.
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 Al wiring material effectively maintains strength and reliability in high-temperature environments, reduces the risk of deformation and cracks, and enhances workability, achieving superior high-temperature reliability with reduced material costs and simplified heat treatment processes.
Implementation Method 1
it has been found that the mechanical strength can be improved by adding scandium (Sc) of 0.05 to 1% by weight to Al to be precipitation-hardened
Implementation Method 2
0.15 to 0.5% by mass of Sc is added to Al and forcibly caused to be solid solution
Implementation Method 3
the wire is precipitation-hardened by an aging heat treatment after connection
Data Source
AI summary
There is provided a novel Al wiring material that suppresses an increase in cold strength and exhibits a favorable high-temperature reliability. The Al wiring material contains one or more selected from the group consisting of Er, Yb and Gd so as to satisfy 0.001≤x1≤0.6 where x1 is a total content thereof [% by mass], with the balance comprising Al.