Perforated EMI Gaskets for Chassis Venting and Shielding

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Solution Overview

Problem

Chassis-mounted electronic devices face challenges in heat management and Electro-Magnetic Interference (EMI) due to the need for balancing airflow and EMI shielding, particularly in high-volume manufacturing where cost-effective solutions are required without compromising performance, and existing methods often lead to thermal bottlenecks and increased costs.

Innovation Solution

The use of upper and lower EMI gaskets with perforations in a chassis constructed from conductive sheets, allowing for increased airflow while providing EMI shielding, which are thinner than the chassis and curved for resilience, enabling efficient cooling and automation in assembly processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If large openings are provided in the chassis for cooling airflow, then heat management is improved, but EMI shielding is compromised

Engineering Contradiction:

Improveheat managementVSAvoidEMI shielding

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent applies perforated EMI gaskets with porous structures that allow airflow through the material while maintaining EMI shielding. The gaskets contain numerous small perforations distributed across their surfaces, enabling cooling airflow to pass through while the remaining solid material continues to provide electromagnetic interference shielding between chassis sections.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent uses composite construction by combining conductive chassis materials with perforated EMI gasket materials. The gaskets are made from conductive materials that provide both structural integrity for EMI shielding and permeability for airflow, creating a composite solution that simultaneously addresses thermal management and electromagnetic compatibility requirements.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If thick conductive sheets are used for chassis to provide EMI shielding, then EMI management is improved, but manufacturing cost and assembly complexity increase

Engineering Contradiction:

ImproveEMI managementVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent segments the EMI shielding function into separate removable gasket components rather than requiring the entire chassis to be constructed from thick conductive material throughout. The gaskets are individual segmented pieces that can be independently manufactured and installed only where EMI shielding is required, reducing overall material usage and manufacturing cost.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs thin, cost-effective EMI gasket materials that can be easily manufactured and replaced if needed, rather than requiring expensive thick conductive sheets for the entire chassis structure. The gaskets serve as economical EMI shielding solutions that can be produced at low cost and installed as needed.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Temperature

If complex thermal solutions are implemented to manage heat, then heat management is improved, but production cost increases

Engineering Contradiction:

Improveheat managementVSAvoidproduction cost

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent enables self-service cooling by providing passive airflow paths through the perforated gaskets that allow natural convection and forced airflow to cool electronic components without requiring complex active thermal management systems. The structure itself provides the cooling function through its perforated design, eliminating the need for additional expensive thermal management components.

Inventive Principle:

Principle #25Self-service

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 solution enhances airflow to manage heat effectively, reduces the need for exotic thermal solutions, allows for the reuse of common components, and lowers production costs by enabling robotic automation, thus addressing thermal challenges and EMI shielding in a cost-effective manner.

Implementation Method 1

EMI management relies on the chassis providing a Faraday cage to contain stray electromagnetic emitted from the electronic devices in the chassis

Methodology Applied

Scientific EffectFaraday cage: Faraday Cage

Implementation Method 2

The upper EMI gasket includes perforations to allow cooling air through the upper EMI gasket and into the interior of the chassis

Methodology Applied

Scientific EffectPerforation flow: Porosity

Data Source

PatentUS11716836B2Electromagnetic compatibility gasket and vent

Publication Date: 2023.08.01 CISCO TECHNOLOGY INC

AI summary

A chassis-mounted electronic device includes a conductive chassis, an upper EMI gasket, and a lower EMI gasket. An upper chassis and a lower chassis of the conductive chassis are coupled to form an interior of the chassis housing an electronic device. The upper EMI gasket is attached to the upper chassis, and resiliently contacts a portion of the electronic device. The lower EMI gasket is attached to the lower chassis, and resiliently contacts a different portion of the electronic device. The upper and lower EMI gaskets include perforations to allow cooling air through the EMI gaskets and into the interior of the chassis. The conductive chassis, the upper EMI gasket, and the lower EMI gasket provide EMI shielding for the electronic device.