Capacitive Sensor Step Substrate for Sensitivity and Breakage
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Solution Overview
Problem
Capacitive sensors face challenges in achieving high sensitivity while minimizing the risk of breakage when brought close to a detection target, as existing designs often require a shorter distance to the target, increasing the likelihood of accidental contact and damage.
Innovation Solution
A capacitive sensor design featuring a sensing electrode, first and second electrode pads, and a substrate with a step portion, where the second electrode pad is positioned lower than the substrate surface, allowing for closer proximity to the detection target while being protected from breakage, and a manufacturing method involving etching and passivation to form these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing electrode is placed closer to the detection target to increase sensitivity, then measurement precision is improved, but the risk of breakage increases due to accidental contact
Solution Approach 1:
The patent introduces a vertical dimension by creating a step portion in the substrate, separating the sensing electrode plane from the electrode pad plane. This dimensional change allows the sensing electrode to be positioned at a lower height (closer to the detection target) while the electrode pads remain at the original substrate surface level, thus improving sensitivity without increasing breakage risk.
Solution Approach 2:
The substrate is segmented into two distinct levels: a substrate surface portion and a step portion. This segmentation allows different functional elements (sensing electrode vs. electrode pads) to be positioned at different heights, enabling the sensing electrode to operate closer to the detection target while the electrode pads remain protected at the higher substrate surface level.
2Measurement precision
If the sensing electrode is placed closer to the detection target, then sensitivity is improved, but device complexity increases due to additional substrate processing
Solution Approach 1:
The patent utilizes the vertical dimension by forming a step portion in the substrate, allowing the sensing electrode to be positioned at a lower level closer to the detection target. This approach achieves improved sensitivity without requiring complex lateral routing or additional processing layers, as the connection between the sensing electrode and electrode pads is achieved through the stepped substrate structure itself.
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 design enhances sensitivity by allowing the sensor to be placed closer to the detection target while minimizing the risk of breakage, improving reliability and reducing manufacturing costs by avoiding complex processing techniques like through-silicon via.
Implementation Method 1
a sensing electrode configured to output a signal corresponding to a capacitance between the sensing electrode and a detection target
Implementation Method 2
forming a step portion by etching an end portion of a substrate
Data Source
AI summary
A capacitive sensor includes a sensing electrode, a first electrode pad, a substrate, and a second electrode pad. The sensing electrode outputs a signal corresponding to a capacitance between the sensing electrode and a detection target. The first electrode pad is coupled to the sensing electrode. The substrate includes a substrate surface portion and a step portion. On the substrate surface portion are the sensing electrode and the first electrode pad mounted. The step portion is provided at a position in the substrate lower than the substrate surface portion. The second electrode pad is mounted on the step portion and coupled to an external line.