Sn-CuNi Bonding Material Void Prevention
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Solution Overview
Problem
Existing bonded products using Sn-based solder materials with a Cu—Sn alloy face challenges in achieving both improved heat resistance and impact resistance due to void formation when Sn with a low melting point is melted and contacted with Cu, leading to deterioration in impact resistance.
Innovation Solution
A bonding material comprising a first layer with Sn as the main component and a second layer with a higher melting point metal, such as a CuNi alloy, laminated together, where the amount of Sn exceeds the stoichiometric amount for forming an intermetallic compound, allowing for heat treatment to form (CuNi)6Sn5, which enhances both heat and impact resistance by preventing void formation and covering the intermetallic compound with Sn.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If Sn-based solder material with Cu-Sn alloy is used for bonding, then heat resistance is improved, but impact resistance deteriorates due to void formation
Solution Approach 1:
The bonding material is divided into multiple functional layers: a first layer containing Sn as the main component, a second layer containing a metal with higher melting point than Sn, and a third layer containing Sn. This segmentation allows different layers to perform different functions - the intermetallic compound layer provides heat resistance while the Sn-containing layers prevent void formation and improve impact resistance
Solution Approach 2:
The second layer containing metal with higher melting point than Sn acts as an intermediary that forms an intermetallic compound with Sn from the first layer. This intermetallic compound layer serves as a mediator that bonds the Sn-based layers while providing thermal stability, preventing direct contact between Sn that would cause void formation
2Strength
If amount of Sn is increased above stoichiometric amount, then impact resistance is improved by preventing void formation, but manufacturing complexity increases
Solution Approach 1:
The invention changes the parameter of Sn content from the stoichiometric amount to an amount exceeding the stoichiometric amount. This parameter change ensures that there is sufficient Sn to form the intermetallic compound and still have excess Sn to prevent void formation and improve impact resistance, while the lamination structure simplifies the manufacturing process
3Reliability
If lamination structure with multiple layers is used, then both heat resistance and impact resistance are improved, but manufacturing complexity increases
Solution Approach 1:
The invention uses a composite lamination structure combining different materials: Sn-based solder material, metal with higher melting point, and excess Sn. This composite structure allows each layer to contribute its specific properties - the intermetallic compound provides thermal stability while the Sn layers provide toughness and void prevention, achieving both heat and impact 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 proposed solution effectively improves heat resistance and impact resistance by forming an intermetallic compound with a higher melting point and covering it with Sn, preventing voids and enhancing the bonding material's toughness, thus effectively bonding objects while improving both thermal and mechanical properties.
Implementation Method 1
forming an intermetallic compound by subjecting the bonding material to a heat treatment at a temperature equal to or higher than the melting point of Sn and lower than the melting point of the metal
Implementation Method 2
forming an intermetallic compound between Sn and the metal having a higher melting point than that of Sn
Implementation Method 3
the melting point of Sn and lower than the melting point of the metal, wherein an amount of Sn in the first layer is larger than a stoichiometric amount of Sn forming an intermetallic compound
Data Source
AI summary
A bonding material having a first layer containing Sn as a main component thereof and a second layer containing a metal having a higher melting point than that of Sn as a main component thereof, wherein the first layer and the second layer are laminated on each other, and an amount of Sn in the first layer is larger than a stoichiometric amount of Sn that forms an intermetallic compound between the Sn and the metal.