Additive Fabrication of Flexible Interconnect Devices
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Solution Overview
Problem
Existing methods for fabricating flexible printed circuits, such as those used in MRI equipment, are wasteful and environmentally harmful, with limited electrical conductivity and high costs due to the use of expensive substrates and subtractive processes that involve copper removal and chemical etching.
Innovation Solution
A print and plate process that uses a substrate with vias formed through conventional methods, followed by the application of a patterned conductive seed layer and a primary conductor layer via electrolytic plating, eliminating the need for photoresist and etching steps, and allowing for higher conductivity and reduced material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a subtractive process is used to fabricate flexible printed circuits, then electrical connections between layers are achieved, but copper material is wasted and manufacturing cost increases
Solution Approach 1:
The patent inverts the traditional subtractive fabrication approach by using an additive process. Instead of depositing copper across the entire substrate and then removing excess material through etching, the invention directly deposits copper only in the required trace patterns and via regions. This inversion eliminates the need for photoresist masking and chemical etching, thereby preventing copper waste while maintaining reliable electrical connections.
Solution Approach 2:
The patent extracts and eliminates the harmful subtractive steps (photoresist application, chemical etching, and photoresist stripping) from the fabrication process. By removing these intermediate steps entirely and replacing them with a direct additive copper deposition method, the process achieves both material efficiency and connection reliability without the waste associated with traditional subtractive manufacturing.
2Manufacturing precision
If traditional photoresist and etching processes are used, then precise copper patterns are achieved, but environmental pollution increases due to chemical waste
Solution Approach 1:
The patent converts the potentially harmful chemical etching process into a beneficial additive deposition process. Instead of using corrosive chemicals to remove copper, the invention uses controlled copper deposition to directly create the desired patterns. This transformation eliminates chemical pollution while maintaining or improving pattern precision, as the copper is deposited only where needed rather than being etched away from a continuous layer.
Solution Approach 2:
The patent replaces the chemical-based etching system with a physical vapor deposition or electroplating system. By substituting chemical reactions with physical deposition processes, the invention eliminates the generation of harmful chemical waste while achieving precise copper patterns through controlled material deposition in the desired trace and via locations.
3Reliability
If expensive polymeric substrates are used for flexible printed circuits, then mechanical reliability is maintained, but manufacturing cost increases
Solution Approach 1:
The patent changes the substrate material parameter from expensive polymeric substrates to cost-effective flexible printed circuit boards. By modifying this material parameter and combining it with the additive copper deposition process, the invention achieves both mechanical reliability and cost reduction, as the FPCB substrate provides sufficient mechanical properties while being significantly less expensive than traditional polymeric substrates.
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 process achieves electrical conductivity greater than half that of copper, reduces material costs by up to 10 times, and minimizes environmental impact by eliminating wasteful subtractive processes and chemical etching, while maintaining mechanical reliability and performance.
Implementation Method 1
printing a patterned conductive seed layer onto the substrate
Implementation Method 2
joining a primary conductor layer to the substrate through an electrolytic plating process
Data Source
AI summary
An interconnect device and a method for fabricating same. An embodiment of the invention includes sequential steps of providing a flexible substrate, forming vias through the flexible substrate, applying a conductive seed layer including first and second portions, applying conductive materials including first and second portions, copper plating the substrate, and then removing the second portions of the conductive seed layer and the conductive materials.