Flat EMI Shield for PCB Cutout Noise Leakage

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Solution Overview

Problem

The challenge is to effectively reduce switching noise leakage through cutouts in printed circuit boards (PCBs) while minimizing the height of electronic apparatuses, particularly in client and edge devices, where conventional EMI shields are too tall and costly, and recessed cavities are expensive to manufacture.

Innovation Solution

A flat EMI shield is mounted to the bottom side of the PCB along the edge of the cutout, coupled to the ground layer through an ohmic contact, which is either flush or surface mounted, reducing the overall height and cost compared to traditional three-dimensional EMI shields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a conventional three-dimensional EMI shield is used to block switching noise leakage through the cutout, then the EMI shielding effectiveness is improved, but the height of the electronic apparatus increases and manufacturing cost increases

Engineering Contradiction:

Improveswitching noise leakageVSAvoidheight of electronic apparatus

Core Design Contradiction:

Object-affected harmful factorsVSLength of moving object

Solution Approach 1:

The patent extracts the essential EMI shielding function from the conventional three-dimensional box structure and implements it using a flat planar shield with strategic cutouts. The flat shield maintains EMI blocking effectiveness by positioning cutouts to align with PCB cutouts, preventing noise paths while eliminating the need for height-consuming vertical structures.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention transitions from a three-dimensional vertical EMI shield to a two-dimensional flat planar shield. This dimensional reduction allows the shield to be mounted flush against the PCB surface, blocking EMI through strategic cutout alignment in the planar domain rather than relying on vertical depth.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If a conventional three-dimensional EMI shield is used to block switching noise leakage through the cutout, then the EMI shielding effectiveness is improved, but the manufacturing cost increases

Engineering Contradiction:

Improveswitching noise leakageVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The flat EMI shield uses simpler, less material-intensive construction compared to three-dimensional shields. The planar design with cutouts requires fewer materials and simpler manufacturing processes, making it a more cost-effective solution that can be easily integrated into PCB assembly without expensive custom molding or complex fabrication.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Object-affected harmful factors

If a recessed cavity is created in the PCB to block switching noise leakage, then the EMI shielding effectiveness is improved, but the manufacturing complexity and cost increase

Engineering Contradiction:

Improveswitching noise leakageVSAvoidPCB manufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of modifying the PCB by creating recessed cavities (complex internal structure), the invention inverts the approach by placing a flat shield on the opposite side of the PCB from the noise source. The shield's cutouts are positioned to align with PCB cutouts, creating EMI blocking paths without requiring complex PCB modifications.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The flat EMI shield acts as an intermediary element between the noise source (inductor) and the sensitive components. Rather than modifying the PCB structure directly or using tall shields, the flat shield mediates EMI blocking through its strategic cutout pattern, simplifying the overall system architecture.

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 effectively blocks switching noise leakage while minimizing the height and manufacturing costs of electronic apparatuses, making it suitable for compact devices like smartphones and IoT devices.

Implementation Method 1

the EMI shield is coupled to the ground layer through an ohmic contact

Methodology Applied

Scientific EffectOhmic contact: Conduction (electrical)

Implementation Method 2

an inductor in a VR within a circuit package may induce switching noises leaking through the cutout of the PCB

Methodology Applied

Scientific EffectElectromagnetic interference shielding: Absorption (EM radiation)

Data Source

PatentUS10645797B2Electromagnetic interference (EMI) shield for a printed circuit board (PCB)

Publication Date: 2020.05.05 INTEL CORP

AI summary

Embodiments herein disclose techniques for electronic apparatuses including a printed circuit board (PCB) and an electromagnetic interference (EMI) shield for the PCB. An electronic apparatus may include a PCB with a plurality of layers including a ground layer. The PCB may include a cutout through the plurality of layers of the PCB. An EMI shield may be mounted to a bottom side of the PCB along an edge of the cutout, where the EMI shield may be coupled to the ground layer through an ohmic contact. The EMI shield may be flat. Other embodiments may also be described and claimed.