Roll-Bonded Al-Cu Laminate Without Intermetallic Interface Cracking
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Solution Overview
Problem
Conventional roll-bonded laminates composed of an aluminum layer and a copper layer face challenges in achieving high peel strength and high tolerance to bonding or bending work due to the formation of intermetallic compounds at the interface, which can lead to lowered peel strength and cracking.
Innovation Solution
The roll-bonded laminate is produced using surface-activated bonding, where the aluminum and copper plates are subjected to sputter etching and then bonded at a reduction ratio of 3% or higher, without or with minimal thermal treatment at temperatures lower than 250°C, thereby avoiding the formation of intermetallic compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermal treatment is applied to achieve high peel strength, then bonding strength is improved, but intermetallic compounds form at the interface causing cracking and peeling
Solution Approach 1:
The invention changes the thermal treatment parameters by limiting the temperature to 250°C or lower, which prevents the formation of intermetallic compounds at the aluminum-copper interface while still achieving sufficient bonding strength through controlled thermal activation of the sputter-etched surfaces
Solution Approach 2:
The invention applies sputter etching as a preliminary action before bonding to create highly reactive surfaces that enhance adhesion between aluminum and copper layers, allowing strong bonding to be achieved without high-temperature thermal treatment that would cause intermetallic compound formation
2Strength
If conventional thermal treatment is used to bond aluminum and copper layers, then bonding strength is achieved, but intermetallic compounds form at the interface
Solution Approach 1:
The invention fundamentally changes the thermal treatment temperature parameter from conventional high temperatures (typically 400-600°C) to a low temperature regime (250°C or lower), which thermodynamically prevents intermetallic compound formation while still enabling bonding through the reactive sputter-etched surfaces
Solution Approach 2:
The invention replaces the conventional thermal diffusion bonding mechanism with a surface-activation mechanism through sputter etching, where mechanical/physical surface modification (sputtering) creates reactive surfaces that bond at lower temperatures without requiring the thermal diffusion that produces harmful intermetallic compounds
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 results in a roll-bonded laminate with peel strength higher than 10 N/cm and high tolerance to bonding or bending work, preventing cracking and peeling, and ensuring reliable performance in applications such as bonding wires and ribbons.
Implementation Method 1
a step of subjecting an aluminum plate to sputter etching; a step of subjecting a copper plate to sputter etching
Data Source
AI summary
A roll-bonded laminate having both high peel strength and high tolerance to bonding or bending work is provided. The roll-bonded laminate is composed of an aluminum layer and a copper layer, which is free of an intermetallic compound containing aluminum and copper at the interface between the aluminum layer and the copper layer, and has a peel strength of higher than 10 N/cm. A method for producing such roll-bonded laminates is also provided.