Phosphoric Acid Immersion for Tin Plating Oxide Inhibition
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Solution Overview
Problem
Current methods fail to effectively inhibit surface oxide formation on metals and metal alloys, which leads to reduced solderability and potential electrical malfunctions in electronic devices, especially during thermal processes where thicker oxides form, and existing solutions either introduce impurities or are costly and non-selective.
Innovation Solution
A composition of phosphoric acids or their salts, combined with water, is applied to metals and metal alloys to inhibit oxide formation, providing a stable grain structure and preventing contamination, while being effective even after reflow processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal processes are applied to complete assemblies after tin plating, then manufacturing completeness is achieved, but surface oxide formation increases and solderability deteriorates
Solution Approach 1:
The patent applies a corrosion inhibitor treatment immediately after tin plating, before the metal surface is exposed to thermal processes. This preliminary protective action prevents oxide formation during subsequent manufacturing steps, allowing thermal processes to be applied without compromising solderability. The inhibitor forms a protective layer that maintains the metal surface in a solderable state throughout the manufacturing process.
2Reliability
If conventional corrosion inhibitors are used, then oxide formation is reduced, but impurities are introduced onto critical areas
Solution Approach 1:
The patent employs a selective corrosion inhibitor treatment that targets only the tin-plated metal surfaces while avoiding contamination of other critical areas. The treatment is applied locally to the metal components during or after plating, ensuring that the corrosion protection is concentrated where needed without introducing impurities onto surrounding areas that would be detrimental to subsequent assembly processes.
3Reliability
If thicker tin layers are deposited to prevent oxide consumption, then solderability is maintained, but material cost and processing complexity increase
Solution Approach 1:
The patent introduces a corrosion inhibitor as an intermediary substance between the tin plating and the thermal environment. This inhibitor layer acts as a mediator that protects the thin tin surface from oxidative consumption during thermal processes, allowing the use of thinner, more cost-effective tin layers while maintaining solderability. The inhibitor mediates the interaction between the metal surface and the thermal environment, preventing direct oxidative damage.
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 phosphoric acid-based composition significantly reduces surface oxide formation on metals and metal alloys, maintaining solderability and preventing electrical malfunctions, with the treatment being effective for several days and compatible with various metal substrates without introducing impurities.
Implementation Method 1
a composition of phosphoric acids or their salts, combined with water, is applied to metals and metal alloys to inhibit oxide formation
Data Source
AI summary
A composition and method for inhibiting corrosion is disclosed. Metals and metal alloys are treated with compositions which contain inorganic and organic acids that prevent oxide formation on the metals and metal alloys.