One-Side Foil Plating via Split Drum Electroplating
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Solution Overview
Problem
Conventional foil-based packaging for integrated circuits is more expensive than leadframe packaging, and existing methods for pre-plating one side of metal foils are not cost-effective, limiting the adoption of foil-based interconnects in semiconductor packaging.
Innovation Solution
A method and apparatus for plating one side of a metallic foil strip by wrapping it around a plating solution drum with the waterline below the break point where the foil unwinds, or using a fountain of metal plating solution with electrodes to conduct an electrical current, ensuring only one side is plated, while the opposing side remains unexposed to the solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional masking methods are used to plate one side of foil, then selective plating is achieved, but manufacturing cost increases
Solution Approach 1:
The patent extracts and removes the masking step from the plating process entirely. By using a split drum design where one half is conductive and the other is non-conductive, the system achieves selective plating without requiring any masking materials or masking operations, thereby eliminating the associated costs and complexity.
Solution Approach 2:
The patent introduces a split drum as an intermediary device between the foil and the plating solution. The drum's dual-sided design (conductive vs. non-conductive) acts as a mediator that automatically directs plating to only the desired surface, replacing the need for masking while maintaining precise control over plating location.
2Ease of manufacture
If foil-based packaging is used instead of leadframe, then packaging cost decreases, but plating process complexity increases
Solution Approach 1:
The split drum serves multiple functions simultaneously: it acts as a plating electrode, a masking structure, a foil support, and a process control mechanism all in one device. This multi-functionality simplifies the overall process by consolidating what would otherwise require separate components and steps.
Solution Approach 2:
The patent applies local quality by making only the conductive half of the drum active for plating, while the non-conductive half remains inactive. This localized approach allows selective plating on one side of the foil without requiring complex process controls, achieving simplicity through targeted functionality.
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 approach allows for efficient and cost-effective plating of one side of metal foils, enhancing the cost competitiveness of foil-based packaging in semiconductor applications by preventing substantial plating on the unexposed surface, thus improving the anchoring of bonding wires and reducing production costs.
Implementation Method 1
The drum is partially immersed in a plating solution such that the waterline of the metal plating solution is below a break point where the metallic foil strip begins to unwind from the plating solution drum. With this arrangement, one side of the metallic foil strip is exposed to the metal plating solution, while the opposing back side of the metallic foil strip does not come in substantial contact with the metal plating solution. In this manner, the exposed side of the foil is plated
Implementation Method 2
Two electrodes are arranged to conduct an electrical current through the fountain and the metallic foil strip
Implementation Method 3
The solution emitting device generates a fountain of metal plating solution that comes in contact with one side of the metallic foil strip. As more of the metallic foil strip passes in front of the solution emitting device and comes in contact with the fountain, more of one side of the metallic foil strip is plated
Data Source
AI summary
Arrangements for plating a single surface of a thin foil are described. In one aspect, a metal foil is wrapped tightly at least partially around a plating solution drum. The drum is partially immersed in a plating solution such that the waterline of the metal plating solution is below a break point where the metallic foil strip begins to unwind from the plating solution drum. With this arrangement, one side of the metallic foil strip is exposed to the metal plating solution, while the opposing back side of the metallic foil strip does not come in substantial contact with the metal plating solution. In this manner, the exposed side of the foil is plated while the back surface of the foil is not plated. The drum may be rotated to convey the foil through the plating solution.