Flux-Cored Solder Alloy Composition for Plated Layer Durability
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Solution Overview
Problem
Existing solder alloys with copper, iron, and tin compositions face issues with the disappearance of protective tin layers when exposed to molten solder, leading to reduced effectiveness and frequent repair needs in soldering processes.
Innovation Solution
A solder alloy composition with specific ranges of iron (0.01-0.1 mass%), cobalt (0.005-0.02 mass%), silver (0.1-4.5 mass%), and copper (0.1-0.8 mass%), with tin as the balance, is used to form a resin flux cored solder that suppresses the disappearance of plated layers during repeated contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Fe is incorporated in the solder alloy, then the disappearance of plated layer is suppressed, but Fe precipitates solely and the effect is insufficient
Solution Approach 1:
The patent uses a composite alloy system containing Fe, Co, Ag, Cu, and Sn. The combination of multiple elements creates synergistic effects where Co prevents Fe precipitation while Ag and Cu maintain solder performance, achieving both plated layer protection and alloy homogeneity
Solution Approach 2:
The patent optimizes the concentration parameters of each element: Fe at 0.01-0.1 mass%, Co at 0.005-0.02 mass%, Ag at 0.1-4.5 mass%, and Cu at 0.1-0.8 mass%. These specific parameter ranges ensure Fe remains dissolved while achieving the desired protective effect
2Reliability
If Ni and Co are incorporated in the solder alloy, then the plated layer disappearance is suppressed, but the flowability and wettability of molten solder are lowered
Solution Approach 1:
The patent carefully controls the concentration of Co at a low level (0.005-0.02 mass%) to provide sufficient plated layer protection while minimizing its negative impact on solder flowability and wettability
Solution Approach 2:
The patent combines Co with Ag and Cu in specific proportions to create a composite alloy that balances plated layer protection with maintained solder flowability and wettability
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 described solder alloy composition effectively prevents the disappearance of plated layers, maintaining soldering efficiency and reducing the need for frequent repairs by optimizing the composition of iron, cobalt, silver, and copper within the solder alloy.
Implementation Method 1
iron that forms the plated layer spreads toward the molten solder layer as a result of the contact between the plated layer and the molten solder
Implementation Method 2
Fe is less likely to spread in Sn in the solder alloy, thereby allowing Fe to solely precipitate
Data Source
AI summary
Provided is a solder alloy that contains 0.01 mass % or more and 0.1 mass % or less of Fe, 0.005 mass % or more and less than 0.02 mass % of Co, 0.1 mass % or more and 4.5 mass % or less of Ag, 0.1 mass % or more and 0.8 mass % or less of Cu, and the balance being Sn.