Embedded Mesh Contact Member for Push-Button Switches

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Solution Overview

Problem

Conventional contact members for push-button switch members face challenges in achieving high corrosion resistance, reliability, and cost-effectiveness, particularly due to exposure of metals like nickel and the need for punching or etching, which can lead to malfunction and increased coating requirements.

Innovation Solution

A contact member design where a wire mesh made of metal wires is embedded in a rubber-like elastic body, with a highly conductive metal coat layer applied only to the exposed regions, reducing metal exposure and coating usage while enhancing conductivity and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal plate is affixed to silicone rubber to achieve low resistance and superior electrical conductance, then electrical conductance is improved, but the flat surface is easily affected by foreign matters interposed between the contact and circuit board

Engineering Contradiction:

Improveelectrical conductanceVSAvoidforeign matter interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies an irregular surface configuration to the contact member, replacing the flat metal plate surface with a curved or irregular profile. This allows the contact to maintain reliable electrical contact even when foreign matters are interposed, as the irregular surface can deform or bridge over small obstacles more effectively than a flat surface.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Object-affected harmful factors

If a wire mesh is used to form an irregular surface that can still contact the circuit board with foreign matters, then resistance to foreign matter interference is improved, but metal exposure increases leading to higher corrosion risk

Engineering Contradiction:

Improveforeign matter interferenceVSAvoidcorrosion resistance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies different properties to different parts of the contact member. The outer peripheral portion is covered with a protective coat layer to prevent corrosion, while the inner portion maintains the irregular surface configuration for foreign matter resistance. This local differentiation allows both requirements to be satisfied simultaneously.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The contact member is divided into distinct regions: an outer peripheral portion with protective coating and an inner portion with irregular surface. This segmentation allows each region to fulfill its specific function - the coated outer region provides corrosion protection while the inner irregular region provides foreign matter resistance.

Inventive Principle:

Principle #1Segmentation

3Reliability

If holes are made when punching or etching is performed and coating metal is applied, then contact reliability is improved, but production cost increases

Engineering Contradiction:

Improvecontact reliabilityVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies the protective coat layer only to the outer peripheral portion of the contact member rather than the entire surface. This partial coating approach reduces the amount of coating material needed and simplifies the manufacturing process while still providing sufficient protection and maintaining contact reliability.

Inventive Principle:

Principle #16Partial or excessive action

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 solution provides a highly reliable and cost-effective contact member that maintains performance even with foreign matter interference, offering improved corrosion resistance and reduced production costs by minimizing metal exposure and coating application.

Implementation Method 1

a meshed contact including one or more layers of a metal other than a noble metal, the meshed contact being embedded in one surface of a rubber-like elastic body in such a manner as to be exposed

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a highly conductive metal coat layer having a higher conductivity than that of the metal in an outermost surface of the meshed contact is provided only on a region of the meshed contact exposed from the rubber-like elastic body

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS10763052B2Contact member, contact member production method, and push-button switch member equipped with contact member

Publication Date: 2020.09.01 SHIN ETSU POLYMER CO LTD

AI summary

In a contact member, a mesh-like contact including one or more layers of a metal other than a noble metal is embedded in such a manner as to be exposed from one of the surfaces of a rubbery elastic body. The contact member includes a highly conductive metal coat layer only in the regions of the mesh-like contact which are exposed from the rubbery elastic body, the coat layer having conductivity higher than that of the metal on the outermost surfaces of the mesh-like contact.