EMI Shield Attenuation Interface for Ground-Free PCB Suppression

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Solution Overview

Problem

Existing electromagnetic interference (EMI) shields for printed circuit boards (PCBs) are costly, space-intensive, and often require electrical grounding, which can lead to performance degradation when displaced or moved, and they typically only operate effectively in a narrow band.

Innovation Solution

The implementation of an EMI shield with an attenuation interface that includes a metal-backed outer perimeter surrounding an EMI absorber, which is compressible and does not require electrical contact to the PCB, allowing for effective EMI noise suppression without grounding, thus enabling increased radio frequency performance and compact device design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional EMI shields are used, then EMI suppression is achieved, but device cost and space consumption increase

Engineering Contradiction:

ImproveEMI suppressionVSAvoidshield structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The EMI shield is divided into a base portion and an attenuation interface portion that can be separately implemented. The attenuation interface includes discrete EMI absorber materials positioned at critical interfaces, rather than requiring a complete enclosed shield structure. This segmentation allows EMI suppression at specific problem areas without the cost and complexity of total shielding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

EMI absorber materials are applied locally at the attenuation interface where EMI problems occur, rather than using uniform shielding throughout the entire device. The metal-backed PCB structure provides localized EMI suppression at the board level, reducing the need for extensive additional shielding components.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If EMI shields require electrical grounding, then EMI suppression is improved, but performance degrades when the shield is displaced or moved

Engineering Contradiction:

ImproveEMI suppressionVSAvoidshield performance stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent replaces the mechanical/electrical grounding system with a material-based EMI absorption system. EMI absorber materials (ferrite, carbon-loaded plastics, rubber, foam, fabric, or paint) are used to suppress EMI through material properties rather than electrical connection, eliminating the reliability issues associated with displaced ground connections.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The attenuation interface uses composite material structures including metal-backed PCBs with EMI absorber materials. These composite materials provide both structural support and EMI suppression functionality, creating a more reliable system that doesn't depend on precise electrical grounding.

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If traditional EMI shields are used, then EMI suppression is achieved, but PCB routing density and component placement flexibility are reduced

Engineering Contradiction:

ImproveEMI suppressionVSAvoidPCB routing density

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The EMI suppression function is extracted from the traditional shield structure and integrated directly into the PCB attenuation interface. The metal-backed PCB with EMI absorber materials provides EMI suppression at the board level, eliminating the need for separate shield components that would consume space and restrict routing flexibility.

Inventive Principle:

Principle #2Taking out (Extraction)

4Object-affected harmful factors

If EMI absorber blocks or gaskets are used, then EMI suppression is improved, but device cost and space consumption increase

Engineering Contradiction:

ImproveEMI suppressionVSAvoidmaterial usage

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The EMI absorber materials are merged with the PCB structure itself, creating an integrated attenuation interface rather than using separate absorber blocks or gaskets. The metal-backed PCB combines structural support with EMI suppression functionality, reducing the quantity of additional materials needed.

Inventive Principle:

Principle #5Merging (Combining)

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 provides effective EMI noise suppression, reduces PCB complexity, and allows for denser circuit board routing and closer component placement, enhancing the compactness of computing devices while being cost-effective and space-efficient.

Implementation Method 1

an inner perimeter having an EMI absorber

Methodology Applied

Scientific EffectElectromagnetic absorption: Absorption (EM radiation)

Data Source

PatentUS12133322B2Electromagnetic interference shields having attentuation interfaces

Publication Date: 2024.10.29 INTEL CORP

AI summary

Electromagnetic interference (EMI) shields having attenuation interfaces are disclosed. A disclosed example EMI shield includes side walls defining sides of the EMI shield, and an attenuation interface to be placed into contact with a circuit board. The attenuation interface includes an inner perimeter having an EMI absorber and an outer perimeter having a metal backing to at least partially surround the EMI absorber.