Bobbin with EMI Shield for Electromagnetic Devices
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Solution Overview
Problem
Electromagnetic devices such as inductors and transformers generate noise that is radiated by the housing into the external environment, leading to premature failure due to excessive temperature from thermal losses.
Innovation Solution
A bobbin assembly with a non-metallic inner and outer body and a metallic shield sandwiched between them, which acts as a thermal interface to conduct heat away from the device while shielding electromagnetic noise from the housing, using thermally conductive materials like plastic and metals like nickel, copper, or aluminum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metallic housing is used to support the EM device, then structural strength and thermal conduction are improved, but electromagnetic noise is radiated into the external environment
Solution Approach 1:
A non-metallic bobbin assembly is introduced as an intermediary component between the EM device and the metallic housing. This bobbin assembly includes a metallic shield that blocks electromagnetic noise while the non-metallic body provides thermal conduction path to the housing, thus mediating between the conflicting requirements of thermal management and EMI shielding.
Solution Approach 2:
The bobbin assembly uses composite construction combining non-metallic materials (for thermal conduction and EMI isolation) with metallic shield (for EMI blocking). This composite structure allows simultaneous achievement of thermal conduction and electromagnetic noise shielding functions that cannot be achieved with a single material.
2Object-generated harmful factors
If a non-metallic bobbin is used to isolate electromagnetic noise, then EMI shielding is improved, but thermal conduction capability deteriorates
Solution Approach 1:
The bobbin assembly combines non-metallic material (providing EMI shielding) with metallic shield and thermally conductive adhesive (providing thermal conduction). This composite structure resolves the contradiction by distributing different functions across different materials within the same assembly.
Solution Approach 2:
The metallic shield and thermally conductive adhesive act as intermediaries that bridge the gap between EMI shielding and thermal conduction requirements, allowing heat to conduct through the non-metallic bobbin while blocking electromagnetic noise.
3Object-generated harmful factors
If a metallic shield is added to block electromagnetic noise, then EMI shielding is improved, but device complexity increases
Solution Approach 1:
The EMI shielding function is merged into the bobbin assembly itself rather than being a separate component. The metallic shield is integrated within the non-metallic bobbin body, combining structural support, thermal conduction, and EMI shielding functions into a single integrated assembly.
Solution Approach 2:
The bobbin assembly is designed as a multi-functional component that simultaneously provides mechanical support, thermal conduction, and electromagnetic noise shielding, eliminating the need for separate components and reducing overall device complexity.
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
Effectively shields electromagnetic noise and manages thermal losses by conducting heat away from the device, preventing excessive temperature and reducing noise radiation from the housing.
Implementation Method 1
heat from the EM device to thermally conduct through the inner and outer bobbin bodies and the shield to the housing
Implementation Method 2
the shield shields noise of the EM device from the housing
Data Source
AI summary
An assembly includes a metallic housing, an electromagnetic (EM) device, and a bobbin in which the EM device is supported. The bobbin has a non-metallic, inner bobbin body, a non-metallic, outer bobbin body, and a metallic shield sandwiched between the inner and outer bobbin bodies. The EM device and the bobbin are mounted in the housing with the bobbin being between the EM device and the housing for heat from the EM device to thermally conduct through the inner and outer bobbin bodies and the shield to the housing while the shield shields noise of the EM device from the housing.