Lead-Free Solder Alloy Composition for Nozzle Corrosion Control
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Solution Overview
Problem
Existing lead-free solder alloys, such as Sn—Ag—Cu-based and Sn—Cu—Ni-based alloys, cause corrosion in spot soldering tanks and nozzles, leading to unstable solder injection and faulty joining due to inadequate corrosion resistance.
Innovation Solution
A lead-free solder alloy composition comprising Ag (0.3 to 4.0% by mass), Cu (0.1 to 2.0% by mass), Fe (0.005 to 0.05% by mass), Ni (0.01 to 0.5% by mass), Ga (0.001 to 0.1% by mass), and Sn as the balance, with optional inclusion of Ge, P, Ti, Si, Mo, Zr, and Mn, which synergistically reduces nozzle corrosion, maintains wettability, and prevents dross formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free solder alloys with high Sn content (such as Sn—Ag—Cu-based and Sn—Cu—Ni-based alloys) are used to reduce global environmental load, then environmental compatibility is improved, but corrosion resistance of dip soldering tanks and spot soldering tanks deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the solder alloy by strictly limiting Fe content to 0.005-0.05 mass% and Ni content to 0.01-0.5 mass%, while optimizing Ag (0.3-4.0 mass%), Cu (0.1-2.0 mass%), and Ga (0.001-0.1 mass%) content. This parameter optimization resolves the contradiction by achieving both environmental compatibility (lead-free) and corrosion resistance through precise compositional control
Solution Approach 2:
The patent creates a composite alloy system combining Sn base metal with precisely controlled amounts of Ag, Cu, Fe, Ni, and Ga elements. This composite material approach allows the solder to simultaneously achieve environmental compatibility (lead-free) and corrosion resistance (through synergistic effects of multiple elements in optimized proportions)
2Object-affected harmful factors
If lead-free solder alloys with high Sn content are used, then environmental compatibility is improved, but corrosion resistance of nozzles used in spot soldering tanks deteriorates, causing unstable solder injection and faulty joining
Solution Approach 1:
The patent optimizes the chemical composition parameters by limiting Fe to 0.005-0.05 mass% and Ni to 0.01-0.5 mass%, while incorporating Ag (0.3-4.0 mass%), Cu (0.1-2.0 mass%), and Ga (0.001-0.1 mass%). This precise parameter control prevents nozzle corrosion and maintains stable solder injection while keeping the alloy lead-free for environmental compatibility
Solution Approach 2:
The patent develops a solder alloy formulation that extends the service life of nozzles by preventing corrosion, effectively replacing the need for frequent nozzle replacement. The optimized composition acts as a protective mechanism that maintains nozzle integrity over extended periods
Data Source
AI summary
A lead-free solder alloy includes Ag in an amount of 0.3 to 4.0% by mass, Cu in an amount of 0.1 to 2.0% by mass, Fe in an amount of 0.005 to 0.05% by mass, Ni in an amount of 0.01 to 0.5% by mass, Ga in an amount of 0.001 to 0.1% by mass, and Sn as the balance.