Solder Alloy Composition for Oxide Film Suppression
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Solution Overview
Problem
Existing solder alloys with Sn as the primary ingredient face issues of discoloration and deteriorated wettability under high temperature and high humidity environments, which can lead to soldering defects, and previous solutions involving Ge and Mn do not effectively address these issues concurrently.
Innovation Solution
A solder alloy composition containing 0.005% to 0.1% by mass of Mn, 0.001% to 0.1% by mass of Ge, and more than 0% to 4% by mass of Ag, with optional additions of P, Ga, Ni, Co, Fe, Bi, In, and Sb, which suppresses oxide film growth and discoloration by distributing Ge oxides on the outermost surface and inhibiting Sn oxide production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ge is added to the solder alloy to suppress discoloration, then discoloration resistance is improved, but wettability deteriorates
Solution Approach 1:
The patent combines Ge and Mn in specific proportions (Ge: 0.001-0.1 mass%, Mn: 0.005-0.1 mass%) to achieve synergistic effects where Ge suppresses discoloration by forming GeO2 on the surface while Mn suppresses Sn oxide formation, together maintaining both discoloration resistance and wettability
Solution Approach 2:
The patent optimizes the concentration parameters of Ge and Mn within specific ranges to balance their competing effects: Ge concentration controls discoloration suppression while Mn concentration controls wettability maintenance, with the optimal ratio being Ge ≥ Mn
2Object-generated harmful factors
If Mn is added to the solder alloy to suppress Sn oxide production, then wettability is improved, but discoloration suppression is insufficient
Solution Approach 1:
The patent combines Ge and Mn in specific proportions (Ge: 0.001-0.1 mass%, Mn: 0.005-0.1 mass%) to achieve synergistic effects where Ge suppresses discoloration by forming GeO2 on the surface while Mn suppresses Sn oxide formation, together maintaining both discoloration resistance and wettability
Solution Approach 2:
The patent optimizes the concentration parameters of Ge and Mn within specific ranges to balance their competing effects: Ge concentration controls discoloration suppression while Mn concentration controls wettability maintenance, with the optimal ratio being Ge ≥ Mn
3Stability of the object's composition
If oxide film growth is allowed under high temperature and high humidity conditions, then natural oxidation occurs, but surface gloss is lost and yellow discoloration occurs
Solution Approach 1:
The patent converts the harmful oxidation reaction into a beneficial protective mechanism by promoting the formation of MnO2 and GeO2 which create a stable, non-yellowing oxide film that protects the underlying Sn from further oxidation while maintaining surface appearance
Solution Approach 2:
The patent changes the chemical composition parameters by adding Ge and Mn in specific proportions to alter the oxidation behavior, transforming the natural oxidation process from harmful (Sn oxide formation causing yellow discoloration) to beneficial (MnO2 and GeO2 formation maintaining surface 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 alloy effectively prevents discoloration and improves fusion properties by maintaining Ge oxides on the surface and suppressing Sn oxide growth, even under harsh environmental conditions, while maintaining wettability and temperature cycle performance.
Implementation Method 1
Ge oxides have any discoloration prevention effect
Implementation Method 2
most Ge oxides are distributed on an outermost surface side of the oxide film containing Sn oxides, Mn oxides and Ge oxides
Implementation Method 3
Mn is easier to produce oxides than Sn and the production of Mn oxides can suppress any growth of the oxide film by change with time of Sn oxides
Implementation Method 4
the wettability deteriorates when the oxide film is insufficiently removed to remain on the surface of the solder ball, thereby causing the fusion properties thereof to deteriorate
Data Source
AI summary
Provided is a solder alloy, a solder ball, a chip solder, a solder paste and a solder joint in which discoloration is suppressed and a growth of an oxide film is suppressed under a high temperature and high humidity environment. The solder alloy contains 0.005% by mass or more and 0.1% by mass or less of Mn, 0.001% by mass or more and 0.1% by mass or less of Ge and more than 0% by mass and 4% by mass or less of Ag, and a principal ingredient of remainder is Sn.