ESD Shield for PCB-Mounted Switches

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Solution Overview

Problem

Existing methods to protect electronic components on a Printed Circuit Board (PCB) from Electro Static Discharge (ESD) are inadequate, as they either fail to prevent high voltage discharges or are impractical due to structural and cost constraints, with prior solutions either trying to prevent ESD from reaching the PCB or directing it away, which is not fully effective.

Innovation Solution

An ESD device with metal components is positioned around the PCB to draw ESD towards controlled points on the PCB, providing a pathway for the electrical current to the same ground used by the PCB, effectively reducing the risk of damage by presenting a low resistance path for the discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an air gap is increased to prevent ESD from reaching the PCB, then ESD protection is improved, but the device size increases and structural limitations are exceeded

Engineering Contradiction:

ImproveESD protectionVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

A conductive shield is introduced as an intermediary element between the ESD source and the PCB. The shield captures ESD energy and directs it to designated discharge points on the PCB, preventing direct damage to sensitive components while maintaining a compact device structure without requiring large air gaps

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts harmful ESD energy into a controlled discharge path by using the conductive shield to capture and redirect the energy to safe discharge points on the PCB, transforming the potentially damaging ESD event into a controlled electrical path that protects sensitive components

Inventive Principle:

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

2Reliability

If insulated barrier material is used to protect the PCB, then ESD protection is improved, but the protection becomes unwieldly and expensive for high voltage discharges

Engineering Contradiction:

ImproveESD protectionVSAvoidprotection structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of using thick insulated barriers to block ESD, a conductive shield is used as an intermediary that actively manages ESD energy by providing a controlled path to discharge points, achieving protection without the complexity and cost of substantial insulation material

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the approach from blocking ESD with insulation to managing ESD through conduction by directing it to specific discharge points, fundamentally altering the protection mechanism from passive barrier to active energy management

Inventive Principle:

Principle #35Parameter changes

3Reliability

If ESD is directed away from the PCB using external ground connections, then ESD protection is improved, but complete protection cannot be achieved due to uncontrolled discharge paths

Engineering Contradiction:

ImproveESD protectionVSAvoiddischarge path control

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The conductive shield serves as an intermediary that captures ESD energy and directs it to designated discharge points on the PCB, providing controlled discharge paths that ensure complete protection of sensitive components unlike external ground connections that cannot fully control the discharge path

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration provides enhanced ESD protection, allowing the PCB to be positioned close to the switch while maintaining high protection levels exceeding 30kV, even in varying environmental conditions, by directing the discharge to the PCB's ground connection, thus preventing damage to sensitive electronics.

Implementation Method 1

In the event an object contacts the actuation surface and an electro static discharge occurs, the electro static discharge is drawn to the frame of the electro static discharge device and down the at least one leg to the ground connection of the PCB

Methodology Applied

Scientific EffectElectro static discharge: Electrostatic Discharge

Implementation Method 2

providing a pathway for the electrical current to the same ground used by the PCB, effectively reducing the risk of damage by presenting a low resistance path for the discharge

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3602594B1Circuit board mounted switch with electro static discharge shield

Publication Date: 2021.10.27 CARLING TECHNOLOGIES INC

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AI summary

An Electro Static Discharge protection device that is provided to protect sensitive electronics on a Printed Circuit Board (PCB) from inadvertent electrical discharge. The protective device is formed as an intervening structure between a contact surface and a PCB and utilizing the same ground as used by the PCB. When an electrical discharge occurs, the discharge is directed toward the PCB and directed to at least one ground point on the PCB so as to avoid damage to sensitive components.