Tin Alloy Electrode Sintering in Air Without Electroplating
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Solution Overview
Problem
Existing electronic components require a tin electroplating process to achieve solderability, which is environmentally harmful and prone to oxidation, and existing methods for base metals in air atmosphere or reduction atmosphere are costly or ineffective.
Innovation Solution
Sintering solderable base metals in air atmosphere using metallic aluminum powder or aluminum protection layers to prevent oxidation, forming electrodes with high solderability and functionality without electroplating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base metal (copper, nickel or copper nickel alloy) is used to replace precious metal silver or silver palladium alloy, then cost is reduced, but heat treatment must occur in reduction atmosphere to preclude oxidation, which greatly increases process cost
Solution Approach 1:
The patent introduces aluminum powder as an intermediary substance that preferentially oxidizes to protect the base metal from oxidation. The aluminum acts as a sacrificial protective layer during heat treatment in air atmosphere, enabling cost-effective base metal electrodes without requiring expensive reduction atmosphere processing
Solution Approach 2:
The patent changes the atmospheric parameter from reduction atmosphere to air atmosphere by introducing aluminum powder. This parameter change allows heat treatment to proceed in simpler, cheaper air environment while still preventing base metal oxidation through the aluminum's preferential oxidation reaction
2Reliability
If tin soldering paste with smaller particles is used to improve solderability, then wettability and rate of dissolving are improved, but the paste is more likely to be oxidized and more expensive
Solution Approach 1:
Aluminum powder serves as a protective intermediary that preferentially oxidizes to shield the tin soldering paste particles from oxidation. This allows the use of fine particle size tin paste for improved solderability without the penalty of increased oxidation susceptibility
Solution Approach 2:
The patent converts the harmful oxidation effect into a beneficial protective mechanism by utilizing aluminum's stronger affinity for oxygen. The aluminum oxidizes first to form a protective barrier, transforming the potential harm of oxidation into a useful protective function
3Reliability
If electroplating process is used to achieve solderability, then solderable electrodes are obtained, but severe pollution to the environment is caused
Solution Approach 1:
The patent replaces the electrochemical plating process with a thermal processing method using aluminum powder protection. This substitution eliminates the need for electroplating equipment, chemicals, and associated environmental pollution while achieving the same solderability outcome
Solution Approach 2:
The patent creates a protective environment using aluminum powder that acts as a barrier against oxidation during heat treatment. This self-generated protective atmosphere replaces the need for controlled inert atmospheres or electroplating baths, reducing environmental impact
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 method enables the production of solderable electrodes with high solderability and functionality by heat treatment, eliminating the need for electroplating and reducing environmental impact.
Implementation Method 1
high oxyphilic characteristics of the metallic aluminum powder or the aluminum protection layer protect the base metal tin conductive paste film or base metal tin alloy conductive paste film against oxidation during high-temperature sintering in air atmosphere
Implementation Method 2
the oxidized base metal tin conductive paste film or base metal tin alloy conductive paste film is reduced to metal and alloy because of strong reduction characteristics of the metallic aluminum powder or the aluminum protection layer
Implementation Method 3
performing heat treatment at 300 ̃600° C. in air atmosphere
Data Source
AI summary
A method of sintering solderable base metals in air atmosphere and manufacturing alloy components to manufacture solderable electrodes by heat treatment instead of electroplating processes. The method involves introducing into an electrode plenty of metallic tin powder directly, then metallic aluminum powder with high-oxidation enthalpy formation to protect tin against oxidation, and other metals, say metallic copper powder, to produce copper-tin alloy to increase the melting point of the electrode. With the method, tin, as a base, directly functions as an electrode, covering the tin electrode with aluminum film to protect the tin electrode against oxidation during heat treatment, introducing appropriate metals, say copper, into the tin film to produce alloy from tin and copper to increase the melting point of the electrode. With electroplating processes replaced by heat treatment, electronic components, i.e., electrodes, are manufactured without any tin electroplating process but exhibit high solderability and excellent functionality.