Copper Bonding Layer With Oxide Coating for Sulfur-Resistant Packaging
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Solution Overview
Problem
Electronic devices using silver or copper pastes as bonding materials fail to withstand sulfur gas tests due to corrosion, and existing solutions do not provide sufficient sulfur resistance, especially in automotive LEDs where stringent sulfurization resistance is required.
Innovation Solution
A bonding layer with copper having a crystal grain size of 50 nm or less, combined with a coating film containing copper oxide, is used to enhance sulfur resistance, with specific composition and thickness ratios of copper (I) oxide and copper (II) oxide in the coating film to prevent sulfur penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver paste is used as bonding material, then thermal conductivity and bonding strength are improved, but sulfur resistance deteriorates due to silver corrosion
Solution Approach 1:
A copper layer is introduced as an intermediary between the silver paste and the environment. The copper layer acts as a sacrificial barrier that forms copper sulfide instead of allowing silver to corrode, thereby protecting the silver bonding material while maintaining thermal conductivity and bonding strength
Solution Approach 2:
The bonding structure is designed as a composite system combining silver paste with a copper protective layer. This composite structure leverages the high thermal conductivity of silver while adding copper's superior sulfur resistance, creating a material system that exhibits both properties simultaneously
2Object-affected harmful factors
If copper paste is used as bonding material, then sulfur resistance is improved compared to silver, but thermal conductivity and bonding strength are insufficient
Solution Approach 1:
The invention merges the advantages of both silver and copper by combining them in a layered structure. The silver paste provides high thermal conductivity and bonding strength, while the copper layer provides sulfur resistance, creating a composite bonding material that exhibits all three properties
3Quantity of substance
If silver sintering paste with small resin content is used, then cost and thermal conductivity are improved, but sulfur resistance deteriorates due to insufficient protection
Solution Approach 1:
The copper layer serves as a protective intermediary that compensates for the reduced resin content in the silver sintering paste. By providing a physical and chemical barrier against sulfur, the copper layer enables the use of low-resin silver paste while maintaining sulfur resistance
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 electronic device exhibits excellent sulfur resistance, as demonstrated by stringent sulfur gas test results, with the copper oxide coating effectively preventing copper sulfide formation and maintaining thermal resistance.
Implementation Method 1
a coating film covering a side of the bonding layer, the coating film containing at least one compound selected from copper (I) oxide (Cu2O) and copper (II) oxide (CuO)
Data Source
AI summary
An electronic device characterized by including a substrate, a bonding layer provided on the substrate, the bonding layer containing copper in an amount of greater than 0 mass % but 60 mass % or less, the copper having its crystal grain size of 50 nm or less, an electronic component provided on the bonding layer, and a coating film covering a side of the bonding layer, the coating film containing at least one compound selected from copper (I) oxide (Cu2O) and copper (II) oxide (CuO).