Flexible PCB Pressure Sensor Using a Ceramic Capacitor Stack
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Solution Overview
Problem
Conventional capacitance-variable pressure sensors in electronic pens require complex and costly fabrication processes due to precise physical connections and metal electrode coating on dielectric media, making them inefficient and expensive to produce.
Innovation Solution
A capacitance-variable pressure sensor design utilizing a double layer flexible circuit board, multi-layer ceramic capacitor, and soft conductive pad, where the ceramic capacitor's internal electrode layers are adherent, eliminating the need for direct metal coating and simplifying assembly, with electrical connections achieved through tin soldering and oxidation resisting surface treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical connection between electrodes and measuring circuits is implemented, then reliable electrical connection is achieved, but fabrication process becomes complicated and inefficient
Solution Approach 1:
The patent merges the electrode and circuit board into a single integrated structure. The flexible circuit board contains conductive traces that directly connect to the capacitor electrodes, eliminating the need for separate connection components and simplifying the fabrication process while maintaining reliable electrical connections.
Solution Approach 2:
The flexible circuit board serves multiple functions: it provides structural support, enables electrical connections through integrated traces, and allows for flexible positioning. This multi-functionality reduces the number of separate components needed and simplifies the overall device structure.
2Measurement precision
If metal electrode is closely positioned in contact with dielectric medium, then capacitance performance is optimized, but processing complexity increases and production cost rises
Solution Approach 1:
The patent uses a flexible circuit board with thin conductive traces instead of rigid metal electrodes. This flexible structure can conform to the dielectric medium surface, maintaining close contact for accurate capacitance sensing while being easier to manufacture and integrate into the device.
Solution Approach 2:
The flexible circuit board combines multiple materials (flexible substrate, conductive traces, insulation layers) into a composite structure that achieves both close contact with the dielectric medium for accurate sensing and ease of manufacturing through standard flexible PCB fabrication processes.
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 design reduces production costs, simplifies assembly, and enables reliable electrical connections, making the sensor more cost-effective and easier to fabricate while maintaining accurate pressure sensing capabilities.
Implementation Method 1
the capacitance between the soft conductive pad and the external electrode(s) of the multi-layer ceramic capacitor varies accordingly
Implementation Method 2
the soft conductive pad deforms so that at least a part of the soft conductive pad moves through the through hole or notch to contact the ceramic dielectric
Data Source
AI summary
A capacitance-variable pressure sensor is disclosed. The capacitance-variable pressure sensor includes a double layer flexible circuit board, a multi-layer ceramic capacitor, and a soft conductive pad. The multi-layer ceramic capacitor is positioned in adjacent to the soft conductive pad. The double layer flexible circuit board is configured with a through hole or a notch, and is positioned between the multi-layer ceramic capacitor and the soft conductive pad. The multi-layer ceramic capacitor is positioned above the through hole or notch, and the soft conductive pad is positioned under the through hole or notch. The multi-layer ceramic capacitor includes a first member and a second member. The first member includes an external electrode or a plurality of external electrodes. The second member includes a ceramic dielectric, and a plurality of internal electrode layers disposed inside the ceramic dielectric. Each external electrode is connected to internal electrode layers.