Tin-Silver-Copper Solder Alloy Composition for Cost Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lead-free tin-silver-copper solder alloys face challenges in achieving reduced silver content while maintaining excellent wettability, fatigue resistance, and suppressing voids (gaps) generation, which are essential for cost reduction and improved performance in electronic circuit boards.
Innovation Solution
A solder alloy composition comprising tin, silver, antimony, bismuth, copper, and nickel, with optional indium and cobalt, where the silver content is between 1.0 and 1.2 mass%, antimony between 0.01 and 10 mass%, and bismuth between 0.01 and 3.0 mass%, optimizing the mass ratios to enhance wettability and prevent oxide formation, thereby ensuring low costs and improved bonding strength and fatigue resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the silver content in tin-silver-copper solder alloy is reduced to lower cost, then the cost is reduced, but the fatigue resistance and connection quality deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the silver content within a narrow range (1.0-1.2 mass%) rather than simply reducing it. This optimized parameter range maintains the necessary fatigue resistance while achieving cost reduction compared to conventional higher silver content alloys. The patent also adjusts copper (0.5-1.0 mass%) and antimony (0.01-10.0 mass%) content to complement the reduced silver level.
Solution Approach 2:
The patent creates a composite solder alloy system by combining tin, silver, copper, and antimony in specific proportions. The interaction between these multiple elements produces synergistic effects where antimony and copper compensate for the reduced silver content, maintaining fatigue resistance through the composite material structure rather than relying on silver alone.
2Quantity of substance
If the silver content is reduced to lower cost, then the cost is reduced, but the wettability deteriorates
Solution Approach 1:
The patent maintains wettability by optimizing the silver content parameter within 1.0-1.2 mass%, which is sufficient to ensure good wetting properties. Additionally, the controlled copper content (0.5-1.0 mass%) contributes to wettability, compensating for any potential deficiency from reduced silver while preventing oxide formation that would harm wettability.
Solution Approach 2:
The patent replaces expensive silver with more economical elements (copper and antimony) that can provide similar wettability functions. This substitution uses cheaper materials to achieve the same functional outcome, reducing overall cost while maintaining manufacturing quality.
3Quantity of substance
If the silver content is reduced to lower cost, then the cost is reduced, but the voids generation increases
Solution Approach 1:
The patent suppresses voids generation by optimizing the silver content parameter within 1.0-1.2 mass%, preventing both excessive silver (which causes voids) and insufficient silver (which compromises connection). The balanced composition with controlled copper and antimony content further prevents oxide inclusion and void formation during soldering.
Solution Approach 2:
The patent applies local quality by ensuring uniform distribution of elements in the solder alloy, particularly maintaining homogeneous silver distribution at the optimized 1.0-1.2 mass% level. This uniform local composition prevents localized void formation and ensures consistent quality throughout the solder joint.
4Quantity of substance
If the solder alloy composition is optimized for reduced silver content, then the cost is reduced, but the melting point and strength balance becomes difficult to maintain
Solution Approach 1:
The patent maintains melting point and strength balance by precisely controlling multiple composition parameters simultaneously: silver (1.0-1.2 mass%), copper (0.5-1.0 mass%), and antimony (0.01-10.0 mass%). This multi-parameter optimization ensures the solder alloy achieves eutectic or near-eutectic composition for appropriate melting characteristics while maintaining mechanical strength.
Solution Approach 2:
The patent creates a balanced composite material system where tin provides the base matrix, silver contributes to strength and wettability, copper enhances conductivity and strength, and antimony refines grain structure and improves strength. The synergistic interaction of these elements maintains both melting point and strength balance despite reduced silver content.
Data Source
AI summary
A solder alloy of a tin-silver-copper solder alloy, containing tin, silver, antimony, bismuth, copper, and nickel, and substantially does not contain germanium, relative to the total amount of the solder alloy, the silver content is more than 1.0 mass% and less than 1.2 mass%, the antimony content is 0.01 mass% or more and 10 mass% or less, and the bismuth content is 0.01 mass% or more and 3.0 mass% or less.