Receptacle Cage EMI Shielding for Optical Modules
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Solution Overview
Problem
Existing optical communication systems face challenges in effectively suppressing electromagnetic noise radiation from the transceiver module to the chassis, particularly due to gaps between the optical module and the receptacle, leading to insufficient countermeasures for radio wave interference.
Innovation Solution
A receptacle cage and transceiver module assembly featuring metal shield members on the periphery, upper, and side surfaces to contact and shield the optical module, preventing noise radiation, along with a connector cover to further secure the optical module and reduce noise leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple EMI gaskets are provided on the front edge and two side edges of the lower opening, then radio wave interference is reduced at those locations, but noise radiation still occurs through the gap between the outer peripheral portion and inner peripheral portion of the optical module receptacle
Solution Approach 1:
The shield member is divided into multiple segments (first shield member, second shield member, third shield member) that are positioned at different locations around the optical module. Each segment independently shields a specific region, collectively covering the entire perimeter including the critical gap between outer and inner peripheral portions, thereby eliminating noise radiation paths that single continuous shielding cannot address.
2Temperature
If a heat sink is provided on the upper surface of the optical module receptacle, then heat dissipation is improved, but electromagnetic noise radiation from the transceiver module to the chassis remains insufficiently suppressed
Solution Approach 1:
The shield member is selectively positioned only at specific locations where noise radiation occurs (around the optical module periphery and at the boundary between connector and module accommodating portions) rather than providing continuous shielding across the entire receptacle. This localized shielding approach suppresses electromagnetic noise radiation while preserving heat dissipation pathways through uncovered areas.
3Ease of operation
If the optical module is detachably accommodated with relative play for easy insertion and removal, then ease of operation is improved, but the gap between outer peripheral portion and inner peripheral portion cannot be tightly sealed
Solution Approach 1:
The shield member acts as an intermediary element positioned between the optical module and the receptacle housing. It contacts the outer peripheral surface of the optical module and extends to shield the gap between outer and inner peripheral portions, effectively blocking noise radiation while allowing the optical module to maintain relative play for easy insertion and removal.
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
The solution reliably suppresses electromagnetic noise radiation from the transceiver module to the outside, enhancing the countermeasure for radio wave interference and ensuring better protection for other electronic components.
Implementation Method 1
a first shield member made of a metal, the first shield member provided on an entire periphery of the module slot and configured to come into contact with an outer peripheral surface of the optical module and to shield electromagnetic noise generated in the module accommodating portion so as to avoid radiation of the noise into the housing
Implementation Method 2
a second shield member made of a metal, the second shield member provided at an upper portion of the connector accommodating portion in a region corresponding to a boundary portion between the connector accommodating portion and the module accommodating portion, and configured to come into contact with an upper surface of the optical module and to shield the electromagnetic noise generated in the connector accommodating portion
Implementation Method 3
third shield members made of a metal, the third shield members provided in regions corresponding to the boundary portion between the connector accommodating portion and the module accommodating portion, the regions being different from a region where the second shield member is provided, the third shield members configured to come into contact with two side surfaces of the optical module and to shield the electromagnetic noise generated in the connector accommodating portion
Data Source
AI summary
In a receptacle cage, a front EMI fingers in a tubular shape serving as a first shield member is provided on the entire periphery of a substantially rectangular module slot. In addition, a gap between outer peripheral surfaces of an upper case as well as a lower plate of an optical module connected to a receptacle connector in a receptacle connector accommodating portion and an inner surface of the cage is shielded by a top EMI fingers serving as a second shield member and side EMI fingers serving as third shield members. Moreover, the lower plate comes into contact with a bottom wall portion which is grounded.