Sensor Conductive Film Pattern Design for Etching Residue Control

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Solution Overview

Problem

Existing sensors with conductive film patterns face productivity issues due to the time and cost required for mirror-finishing the base material surface, and are prone to short-circuit failures caused by etching residues when formed on surfaces with streaks.

Innovation Solution

A sensor design featuring a base material with a surface having streaks, where a conductive film pattern is formed in a shape with a longer conductive path than a straight line connecting different positions, ensuring that straight lines parallel to the streak direction pass across the conductive path center line zero times or once, thereby minimizing the risk of short-circuit failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the surface of the base material is mirror-finished to prevent short-circuit failures, then the reliability of the conductive film pattern is improved, but the productivity is deteriorated due to the time and cost required for mirror-finishing

Engineering Contradiction:

Improvereliability of conductive film patternVSAvoidproductivity of sensor manufacturing

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the expensive and time-consuming mirror-finishing process with a simpler surface treatment that creates streaks in a specific direction. This disposable-like approach uses a low-cost surface preparation method that eliminates the need for high-precision mirror polishing while still preventing short-circuit failures through the directional streak pattern that controls etching residue movement.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Productivity

If the surface of the base material is not mirror-finished to improve productivity, then the productivity is improved, but the reliability is deteriorated due to short-circuit failures caused by etching residues

Engineering Contradiction:

Improveproductivity of sensor manufacturingVSAvoidreliability of conductive film pattern

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent converts the potentially harmful effect of surface streaks (which could cause etching residues) into a beneficial feature. By deliberately creating streaks in a specific direction and designing the conductive film pattern to interact with these streaks, the patent ensures that etching residues are directed away from critical areas, thus preventing short-circuit failures without requiring mirror-finishing.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces asymmetry in the conductive film pattern design, specifically in how the pattern interacts with the directional streaks on the surface. The conductive film is configured with specific geometric features that exploit the asymmetric streak pattern to prevent residue accumulation in critical areas, thereby maintaining reliability without mirror-finishing.

Inventive Principle:

Principle #4Asymmetry

3Productivity

If a conductive film pattern is formed on a surface with streaks, then the productivity is improved by eliminating mirror-finishing, but the manufacturing precision is deteriorated due to etching residues

Engineering Contradiction:

Improveproductivity of sensor manufacturingVSAvoidprecision of conductive film pattern

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by designing the conductive film pattern with different geometric characteristics in different regions. Specifically, the pattern is configured to have areas that are more resistant to etching residue accumulation in critical regions, while allowing streaks to exist in non-critical areas. This localized optimization maintains manufacturing precision where needed while enabling productivity improvements overall.

Inventive Principle:

Principle #3Local quality

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 effectively prevents short-circuit failures by controlling the path of etching residues and improves productivity by eliminating the need for mirror-finishing, while maintaining the sensitivity and accuracy of the conductive film pattern.

Implementation Method 1

there is a circuit in which strain of a base material (also referred to as membrane or diaphragm) is detected by a resistance change using a piezoresistive effect

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentUS20250110000A1sensor

Publication Date: 2025.04.03 TDK CORP

AI summary

A sensor including: a base material having a surface on which streaks are formed along a first direction in a plan view; and a conductive film pattern formed on or above the surface and configured to connect mutually different positions in an in-plane direction of the surface in a shape in which a length of a conductive path is longer than a length of a straight line connecting the different positions, in which in a plan view, the shape of the conductive film pattern comprises a shape in which each of straight lines parallel to the first direction passes across a conductive path center line of the conductive film pattern zero times or once but does not pass across the conductive path center line twice or more.