Plating Apparatus Shielding Walls Bipolar Phenomenon
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Solution Overview
Problem
The existing plating apparatuses, such as those described in WO 2017/217216, suffer from a bipolar phenomenon that leads to oxidative dissolution of the conductive portions of the plating object due to current flowing through the plating solution, resulting in uneven current density and reduced reliability of the plated film.
Innovation Solution
The proposed plating apparatus incorporates a partition wall that allows the plating solution to pass through but not the plating object, with a mixing portion above the cathode where the plating solution and object are mixed, and uses a first and second shielding wall configuration to guide the fluid mixture, preventing current from flowing from the anode to the cathode via the plating solution, thereby reducing the bipolar phenomenon and ensuring uniform current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plating solution is allowed to flow freely from anode to cathode, then electrolytic plating can be performed, but bipolar phenomenon occurs causing oxidative dissolution
Solution Approach 1:
The plating tank is divided into multiple compartments by partition walls. The first partition wall divides the tank into an anode compartment and a plating compartment, while the second partition wall further divides the plating compartment into a plating object passage compartment and a plating solution passage compartment. This segmentation prevents direct current flow from anode to cathode through the plating solution, eliminating the bipolar phenomenon while maintaining reliable plating.
Solution Approach 2:
Partition walls act as intermediaries that separate the anode, plating objects, and plating solution flow paths. The partition walls allow plating solution to pass through (via permeable sections) while preventing direct electrical conduction between anode and cathode, thus mediating the plating process to avoid harmful current paths.
2Manufacturing precision
If plating objects are placed in direct contact with cathode, then electrolytic plating can be performed, but current density distribution becomes highly uneven
Solution Approach 1:
A partition wall is introduced as an intermediary between the cathode and plating objects. This partition wall allows plating solution to pass through to the plating objects while preventing direct electrical contact between cathode and plating objects. This mediation enables uniform current density distribution across all plating objects simultaneously, achieving consistent film thickness.
Solution Approach 2:
The partition wall creates a three-dimensional plating environment where plating solution can flow around plating objects from multiple directions (upward and downward flows). This multi-directional solution access ensures uniform current distribution and film thickness across plating objects, transitioning from simple contact plating to controlled solution-mediated plating.
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 configuration effectively reduces the current flowing from the anode to the cathode, preventing oxidative dissolution and ensuring a uniform plating film thickness, thereby enhancing the reliability and consistency of the plated object.
Implementation Method 1
a partition wall which allows the plating solution to pass through but does not allow the plating object to pass through
Implementation Method 2
an injector which injects the plating solution upward
Implementation Method 3
performing an electrolytic plating on the plating object by applying a voltage between an anode which is disposed outside the plating object passage and a cathode which is disposed inside the plating object passage
Implementation Method 4
a first shielding wall which is disposed above the cathode and outside the cathode when viewed in an extending direction of the plating object passage to guide the fluid mixture to pass through the hollow region downward; and a second shielding wall which is disposed outside the first shielding wall
Data Source
AI summary
A plating apparatus includes a plating tank and a plating unit. The plating unit includes a partition wall allowing the plating solution to pass through but not allowing the plating object to pass through, and defines inside thereof a plating object passage through which the plating object passes, an injector which injects the plating solution upward, a mixing portion in which the plating solution and the plating object are mixed, an anode outside the plating object passage, a cathode inside the plating object passage with a hollow region through which a fluid mixture of the plating solution and the plating object passes upward, a first shielding wall which guides the fluid mixture downward, and a second shielding wall outside the first shielding wall. A lower end of the first shielding wall is lower than an upper end of the second shielding wall.