Al Wiring Alloy Composition for High-Temperature Bond Reliability
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Solution Overview
Problem
Aluminum wiring materials used in industrial devices and semiconductor devices face challenges in maintaining high-temperature reliability and workability due to softening at elevated temperatures, leading to potential disconnection and reduced bonding strength, especially under repetitive thermal stress and high-voltage cycling.
Innovation Solution
An Al wiring material composition containing Mg and Si within specific ranges, combined with Sc, Er, Yb, Gd, Ce, or Y, and optionally Zr, Fe, Ni, Mn, Cu, and Zn, which allows for improved high-temperature reliability and workability through low-temperature or short-time heat treatments, reducing the risk of cracking and peeling-off during thermal cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high purity Al is used as wiring material, then electrical conductivity is improved, but softening occurs in high temperature environment leading to reduced strength
Solution Approach 1:
The patent uses Al-Si-Mg alloy composite material instead of high purity Al. The specific composition (Si: 0.03-0.8 wt%, Mg: 0.03-0.2 wt%) creates a composite structure that combines the high electrical conductivity of Al with the strength-enhancing effects of Si and Mg, preventing softening at high temperatures while maintaining conductivity.
Solution Approach 2:
The patent changes the chemical composition parameters of the wiring material by adding controlled amounts of Si and Mg elements. This parameter modification transforms the material properties to achieve both high electrical conductivity and high-temperature strength, resolving the contradiction between conductivity and strength.
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 composition parameters (Si: 0.03-0.8 wt%, Mg: 0.03-0.2 wt%) to achieve the optimal balance. This controlled parameter change provides sufficient high-temperature reliability while keeping the material workable and bondable, avoiding the deterioration that occurs with excessive element addition.
Solution Approach 2:
The patent applies local quality enhancement by adding small, controlled amounts of Si and Mg specifically to the Al matrix. This localized compositional modification provides the necessary strength and high-temperature reliability without uniformly compromising the overall workability and bondability of the wiring material.
3Strength
If heat treatment is performed to improve high temperature reliability, then strength is improved, but productivity decreases and thermal stress on connected parts increases
Solution Approach 1:
The patent incorporates strength-enhancing elements (Si and Mg) directly into the wiring material composition during manufacturing, providing high-temperature strength in advance. This preliminary action eliminates the need for subsequent heat treatment processes, thereby improving productivity and avoiding thermal stress on connected components.
Solution Approach 2:
The patent extracts the heat treatment step from the manufacturing process by incorporating the strength-enhancing function directly into the material composition. This removal of the heat treatment process improves productivity and eliminates the associated thermal stress issues while maintaining high-temperature strength.
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 proposed Al wiring material achieves enhanced bonding strength and high-temperature reliability, maintaining performance even after 100,000 power cycles, while allowing for reduced heat treatment temperatures and times, thus improving productivity and reducing thermal stress on connected components.
Implementation Method 1
containing Mg and Si so as to satisfy 0.05≤x1a≤2.5, 0.02≤x1b≤1, and 0.1≤(x1a+x1b)≤3 where x1a is a content of Mg [% by mass] and x1b is a content of Si [% by mass]
Implementation Method 2
Patent Literature 2 discloses an Al bonding wire the mechanical strength of which is improved by adding scandium (Sc) of 0.05 to 1% by weight to Al to be precipitation-hardened
Implementation Method 3
containing one or more selected from the group consisting of Sc, Er, Yb, Gd, Ce and Y so as to satisfy 0.001≤x2≤0.5 where x2 is a total content thereof [% by mass]
Implementation Method 4
allows for improved high-temperature reliability and workability through low-temperature or short-time heat treatments
Data Source
AI summary
There is provided a novel Al wiring material that achieves a favorable high-temperature reliability as well as a favorable workability and bondability during installation and connection to a device. The Al wiring material contains Mg and Si so as to satisfy 0.05≤x1a≤2.5, 0.02≤x1b≤1, and 0.1≤(x1a+x1b)≤3 where x1a is a content of Mg [% by mass] and x1b is a content of Si [% by mass], and contains one or more selected from the group consisting of Sc, Er, Yb, Gd, Ce and Y so as to satisfy 0.001≤x2≤0.5 where x2 is a total content thereof [% by mass], with the balance comprising Al.