Multi-Layer Flexible Circuit Board Manufacturing with PTFE Substrate
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Solution Overview
Problem
Conventional multi-layer flexible circuit boards face challenges in adapting to high-frequency and high-speed trends due to high dielectric constant, loss factor, moisture absorption, and poor reliability of PI substrates, leading to increased signal transmission loss and copper ion migration issues, which can cause safety hazards.
Innovation Solution
A method for manufacturing a multi-layer flexible circuit board using a double-sided FPC flexible board with novel material layer structures, incorporating semi-cured high-frequency material layers and copper ion migration resistant adhesives, and thermoforming to integrate these layers, reducing thickness and power consumption while enhancing high-frequency signal transmission and preventing copper ion migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PI substrate is used in conventional soft boards, then the manufacturing process is established and reliable, but the dielectric constant and loss factor increase leading to high signal transmission loss at high frequencies
Solution Approach 1:
The patent changes the material parameter by replacing PI substrate with PTFE substrate, which has fundamentally different dielectric properties (lower dielectric constant and loss factor), thereby reducing signal transmission loss at high frequencies while maintaining manufacturing reliability
Solution Approach 2:
The patent uses composite material structure by combining PTFE substrate with copper foil and protective layers to create a multi-layer flexible circuit board that achieves both low signal loss and structural integrity
2Ease of manufacture
If PI substrate is used in soft boards, then the substrate is widely available and easy to manufacture, but moisture absorption increases and reliability decreases
Solution Approach 1:
The patent changes the material parameter by substituting PI with PTFE substrate, which has inherently lower moisture absorption properties, thereby improving operational reliability while PTFE remains a widely available industrial material
3Reliability
If conventional multi-layer structure is used, then the circuit board has basic protective and isolating functions, but the overall thickness is large and manufacturing complexity increases
Solution Approach 1:
The patent extracts and eliminates redundant layers from the conventional multi-layer structure, keeping only the essential PTFE substrate, copper foil, and protective layers, thereby reducing overall thickness while maintaining circuit protection functions
Solution Approach 2:
The patent segments the circuit board into functional layers (PTFE substrate, copper conductor layer, protective layer) that can be manufactured and assembled independently, simplifying the overall manufacturing process while maintaining protection functions
4Ease of manufacture
If conventional manufacturing process is used, then the process is established and proven, but power consumption increases and signal transmission loss occurs
Solution Approach 1:
The patent changes the substrate material parameter from PI to PTFE, which has lower dielectric loss, thereby reducing power consumption during signal transmission while maintaining process stability through established lamination and manufacturing techniques
5Strength
If conventional adhesive layers are used, then the layers are bonded and structured, but copper ion migration occurs between lines causing safety hazards
Solution Approach 1:
The patent introduces a barrier layer as an intermediary between copper foil layers, which prevents copper ion migration while maintaining layer bonding strength, thereby eliminating safety hazards without compromising structural integrity
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 simplifies the manufacturing process, improves production efficiency, and achieves high-speed, low-loss signal transmission, ensuring safe operation by preventing copper ion migration and reducing the risk of circuit failures and hazards.
Implementation Method 1
thermoforming: hot-pressing at least one group of novel material layer structures on the circuits of the upper surface and/or the lower surface of the double-sided FPC flexible board
Data Source
AI summary
The present invention discloses a method for manufacturing a multi-layer flexible circuit board, comprising the steps of: (1) manufacturing a double-sided FPC flexible board; (2) manufacturing a novel material layer structure; (3) hot pressing at least one group of upper novel material layer structures on the circuits on the upper and/or lower surfaces of the double-sided FPC flexible board; forming a protective layer on the circuits of an outermost novel material layer structure and/or on exposed circuits of the double-sided FPC flexible board so as to obtain a multi-layer flexible circuit board. The present invention also discloses a multi-layer flexible circuit board manufactured by performing the above-mentioned method. The manufacturing process of the present invention is simplified, convenient and efficient; the multi-layer flexible circuit board not only greatly simplifies the novel material layer structure and reduces the overall thickness, but also has the function of high-speed transmission of high-frequency signals, especially suitable for new 5G technology products. It can protect and resist the migration of copper ions when it is energized between circuits so as to ensure the safety and normal operation of circuits.