Sn-Cu Solder Alloy Composition for Oxidation-Resistant Casting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing Sn—Cu based solder alloys used in continuous casting methods suffer from oxidation and decreased flowability due to atmospheric exposure, making it difficult to achieve a cast product with desired thickness and wettability, particularly in flow soldering and continuous casting processes.
Innovation Solution
A solder alloy composition with optimized Cu, Ni, P, and Ge content, balanced to control liquidus temperature and flowability, along with additional elements like Bi, In, Zn, and rare earth elements, to enhance castability and prevent oxidation, within specific mass percentage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Sn-Cu based solder alloy is cast by continuous casting method in atmosphere, then production efficiency is improved, but oxidation occurs and flowability decreases
Solution Approach 1:
The patent applies inert atmosphere protection by introducing a protective gas environment (argon or nitrogen atmosphere) during the continuous casting process. This prevents oxidation of the molten Sn-Cu solder alloy while maintaining high production efficiency. The inert gas creates a protective environment that eliminates oxygen contact with the molten metal throughout the casting process.
2Reliability
If oxidation prevention measures are taken, then solder quality is improved, but process complexity increases
Solution Approach 1:
The patent changes the atmospheric parameters by controlling the oxygen partial pressure through inert gas atmosphere. This parameter change prevents oxidation without requiring complex additional equipment. The simple introduction of argon or nitrogen gas creates the necessary protective environment, maintaining process simplicity while ensuring high solder quality.
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 optimized solder alloy composition ensures the production of cast products with desired thickness and improved flowability, suitable for both continuous casting and fixed mold casting methods, by controlling the viscosity and liquidus temperature effectively.
Implementation Method 1
the oxidation of the molten solder progresses due to oxygen in the atmosphere
Implementation Method 2
the cooling rate up to 280° C. is 3° C./s or more, preferably 20° C./s or more, and more preferably 50° C./s or more
Data Source
AI summary
A solder alloy has an alloy composition consisting of, in mass %, Cu: 0.1% to 2.0%, Ni: 0.01% to 0.4%, P: 0.001% to 0.08%, and Ge: 0.001% to 0.08%, with the balance being Sn. The alloy composition satisfies the following relations (1) to (3): (Cu+5Ni)≤0.945% (relation (1)), (P+Ge)≤0.15% (relation (2)), 2.0≤(Cu+5Ni)/(P+Ge)≤1000 (relation (3)). In the above relations (1) to (3), Cu, Ni, P, and Ge each represents a content (mass %) thereof in the solder alloy.