Tin Plating Bath Polonium Removal via Electrodeposition
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Solution Overview
Problem
The electronics industry faces challenges in reducing alpha particle emissions from semiconductor devices due to the presence of alpha particle emitting species like Polonium (Po) in plating baths used for conductive elements, which are costly and affect the reliability of semiconductor devices.
Innovation Solution
A method is developed to selectively plate Tin (Sn) while suppressing the plating of Polonium (Po) using pulse plating with current or potential control, or by using a filtering anode and cathode to plate out Po, thereby reducing alpha particle emissions from the semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low alpha particle emitting electrically conductive materials are used in plating baths, then alpha particle emissions are reduced, but the cost increases 2-7 times
Solution Approach 1:
The patent extracts and removes alpha particle emitting species (such as Polonium) from the plating bath through electrochemical methods. A filtering cathode is used to selectively plate out and remove these harmful species from the concentrate, separating them from the desired metal species. This allows the use of standard, cost-effective plating materials while achieving low alpha particle emissions in the final product.
Solution Approach 2:
The patent applies preliminary action by performing alpha particle emitting species removal before the main plating process. The concentrate is pre-treated through electrochemical reduction where alpha particle emitting species are plated onto the filtering cathode, reducing their concentration in advance. This preliminary purification step enables subsequent plating with standard materials to produce low-alpha final products.
2Ease of manufacture
If standard electrically conductive materials with trace alpha particle emitting particles are used, then cost is reduced, but alpha particle emissions increase
Solution Approach 1:
The patent introduces an intermediary electrochemical processing step between material selection and final plating. The filtering anode-cathode system acts as an intermediary mechanism that selectively removes alpha particle emitting species from the concentrate. This intermediary process enables the use of cost-effective standard materials while achieving the required low alpha particle emission levels through controlled electrochemical separation.
3Manufacturing precision
If pulse plating with current or potential control is used to selectively plate Sn, then Sn concentration increases and Po incorporation is minimized, but process complexity increases
Solution Approach 1:
The patent employs periodic action through pulse plating techniques where current or potential is applied in pulses rather than continuously. This periodic application of electrical parameters enables selective plating of Sn while suppressing Po incorporation. The pulsed nature of the process allows control over deposition rates and selectivity, achieving high manufacturing precision through time-varying electrical parameters.
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
This method effectively reduces alpha particle emissions by increasing the concentration of Sn while minimizing the incorporation of Po, resulting in purified solder bumps with reduced alpha particle emissions, addressing the cost and reliability issues associated with low alpha particle emitting materials.
Implementation Method 1
reducing the alpha emitting species from the concentrate by plating the alpha emitting species upon the filtering cathode
Data Source
AI summary
A plating product fabrication method includes forming a first concentrate. The concentrate includes a metal species, such as Tin, and a trace amount of an alpha emitting species, such as Polonium. The plating product fabrication method also includes creating a circuit between a filtering anode and a filtering cathode and reducing the alpha emitting species from the concentrate by plating the alpha emitting species upon the filtering cathode. In this manner, a purified concentrate is formed. The purified concentrate may be utilized to plate the metal species upon a plating cathode. The purified concentrate may be utilized to form a purified metal species.