Board-to-Board Connector Inverted Cantilever Spring EMI Shielding

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Solution Overview

Problem

Existing board-to-board connectors fail to effectively block spatial conduction of electromagnetic waves, leading to increased electromagnetic interference (EMI) in high-density electronic devices with high-frequency signal transmission.

Innovation Solution

The board-to-board connector features a cantilever spring positioned in a slit within the conductive shell, extending in the opposite direction to conventional designs, with its fixed end near the attachment point and free end facing the counterpart connector, enhancing grounding performance and reducing EMI by positioning the slit closer to high-frequency contacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the cantilever spring extends in the conventional direction (free end near the board), then the structure is simple and easy to manufacture, but the grounding performance is insufficient and EMI is not effectively reduced

Engineering Contradiction:

Improveelectromagnetic interference (EMI)VSAvoidcantilever spring configuration

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent inverts the conventional cantilever spring configuration by positioning the fixed end near the board and the free end facing the counterpart connector. This inversion changes the grounding path and enables the slit to be positioned closer to high-frequency contacts, effectively blocking spatial conduction of electromagnetic waves and reducing EMI.

Inventive Principle:

Principle #13The other way round (Inversion)

2Object-affected harmful factors

If the slit is positioned far from high-frequency contacts, then the manufacturing is easier, but the shielding effectiveness against electromagnetic waves is reduced

Engineering Contradiction:

Improvespatial conduction of electromagnetic waveVSAvoidslit positioning

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

By inverting the cantilever spring configuration, the patent enables the slit to be positioned closer to the high-frequency contacts without increasing manufacturing difficulty. The inverted structure naturally positions the slit in the optimal location for blocking electromagnetic wave conduction paths.

Inventive Principle:

Principle #13The other way round (Inversion)

3Object-affected harmful factors

If the cantilever spring free end faces the board, then the grounding path is shorter, but the grounding performance is insufficient for blocking electromagnetic waves

Engineering Contradiction:

Improvegrounding performanceVSAvoidcantilever spring extension direction

Core Design Contradiction:

Object-affected harmful factorsVSLength of moving object

Solution Approach 1:

The patent inverts the cantilever spring extension direction so that the free end faces the counterpart connector rather than the board. This inversion creates an optimal grounding path that effectively blocks spatial conduction of electromagnetic waves while maintaining electrical connection.

Inventive Principle:

Principle #13The other way round (Inversion)

4Object-affected harmful factors

If conventional connector configuration is used, then the device complexity is low, but intrasystem electromagnetic interference increases due to high-density mounting

Engineering Contradiction:

Improveintrasystem electromagnetic interferenceVSAvoidconnector structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies inversion to the cantilever spring configuration within the connector structure. This single structural inversion effectively blocks electromagnetic wave conduction paths without requiring changes to the overall connector architecture, maintaining compatibility with high-density mounting requirements.

Inventive Principle:

Principle #13The other way round (Inversion)

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 significantly reduces EMI by improving grounding performance and shielding, as evident from the comparison graphs showing lower radiation electric field strength across various frequencies.

Implementation Method 1

it is important to block the spatial conduction of an electromagnetic wave from the inside of the board-to-board connector by means of a conductive shell electrically connected with the ground pad of the board

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

the contact pieces are in contact with an inner wall surface of a shell of the second electrical connector 20. This contact provides electrical connection between the first electrical connector 10 and the second electrical connector 20

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11489291B2Board-to-board connector and connector assembly

Publication Date: 2022.11.01 JAPAN AVIATION ELECTRONICS IND LTD

AI summary

A cantilever spring is positioned in a slit in a shell, and has a free end and a fixed end fixed to the shell. The cantilever spring extends in a height direction of the shell. The fixed end of the cantilever spring is positioned near a part that is attachable to a board, and the free end of the cantilever spring is apart from that part.