Grounded EMI Absorbing Leadframe for Optical Transceiver Shielding
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Solution Overview
Problem
Existing EMI sealing solutions in optical transceiver modules are incomplete as they only absorb magnetic components of electromagnetic interference and fail to prevent resonant frequency modes, necessitating a more effective shielding method.
Innovation Solution
An EMI absorbing assembly comprising an electrically conductive leadframe with EMI absorbing material, secured to the leadframe and grounded to the module's housing, which absorbs both magnetic and electrical components and mitigates resonant modes by shaping the leadframe to prevent such occurrences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a sheet of EMI absorbing material is placed in free space in the housing, then magnetic components of EMI are absorbed, but electrical components are not absorbed and resonant modes are not prevented
Solution Approach 1:
The patent combines EMI absorbing material with a conductive leadframe structure to create a composite assembly. The absorbing material handles magnetic field absorption while the conductive leadframe provides electrical field shielding and resonant mode suppression through its grounded conductive paths, achieving complete EMI sealing.
Solution Approach 2:
The conductive leadframe acts as an intermediary between the EMI absorbing material and the housing ground. It provides a controlled impedance path that connects the absorbing material to ground while also serving as a shield for electrical field components, enabling both magnetic and electrical EMI protection.
2Object-affected harmful factors
If the housing cavity length allows resonant frequency modes to occur, then EMI radiation can propagate, but modifying the cavity structure increases device complexity
Solution Approach 1:
The conductive leadframe serves as an intermediary structure placed within the existing housing cavity. It provides resonant mode suppression through its conductive paths and grounding connections without requiring modification of the housing cavity itself, maintaining structural simplicity while achieving EMI control.
Solution Approach 2:
The patent changes the electrical parameters of the housing by introducing the conductive leadframe with specific impedance characteristics. This modifies the electromagnetic boundary conditions within the cavity to suppress resonant modes without altering the physical dimensions or structural parameters of the housing.
3Loss of energy
If EMI absorbing material is used without electrical grounding, then magnetic EMI is absorbed, but the assembly cannot effectively shield electrical EMI components
Solution Approach 1:
The patent creates a composite structure where the EMI absorbing material is integrated with the conductive leadframe. The absorbing material provides magnetic field attenuation while the conductive leadframe provides electrical field shielding through its grounded structure, achieving comprehensive EMI protection.
Solution Approach 2:
The conductive leadframe acts as an intermediary that connects the EMI absorbing material to the housing ground. This connection enables the absorbing material to be electrically grounded, allowing it to effectively shield both magnetic and electrical EMI components through the combined action of absorption and grounding.
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 effectively shields both magnetic and electrical EMI components, reducing the occurrence of resonant modes and enhancing overall EMI sealing compliance, thereby improving the module's electromagnetic interference shielding performance.
Implementation Method 1
One of the problems associated with using a sheet of absorbing material disposed in free space in the housing is that it absorbs the magnetic, but not the electrical, components of the EMI
Implementation Method 2
The leadframe of the EMI absorbing assembly is electrically conductive and has an EMI absorbing material secured thereto
Data Source
AI summary
An optical transceiver module is provided that has an EMI absorbing assembly that comprises an EMI absorbing device that is electrically grounded rather than standing in free space in the transceiver module so that the assembly absorbs both the magnetic and electrical components of the EMI. In accordance with an embodiment, the EMI absorbing assembly includes a leadframe about which an EMI absorbing material is cast. The leadframe preferably is shaped in a way that prevents or lessens the occurrence of resonant EMI modes in the transceiver module housing.