Heat Sink EMI Reduction via Conductive Tape
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Solution Overview
Problem
Existing heat radiation structures for electronic devices, such as those using a heat sink and electromagnetic wave absorption sheets, fail to sufficiently reduce electromagnetic interference (EMI) due to capacitive coupling between the heat sink and heat spreader, and can act as antennas when the heat sink is larger than a quarter wavelength of the electromagnetic wave frequency.
Innovation Solution
A heat radiation structure that includes a heat spreader on a substrate, a heat sink facing the spreader, a heat transfer member between them, and a conductive member, like a conductive tape, electrically connecting the spreader and sink to weaken capacitive coupling and reduce EMI by ensuring the potential of both is identical, thus minimizing electromagnetic wave radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat sink is used to dissipate heat from the heating component, then heat radiation efficiency is improved, but electromagnetic wave radiation increases due to capacitive coupling between the heat sink and heat spreader
Solution Approach 1:
An electromagnetic wave absorption sheet is introduced as an intermediary layer between the heat sink and the heating component. This absorption sheet has both thermal conductivity to maintain heat dissipation functionality and electromagnetic wave absorbing properties to reduce EMI. The sheet acts as a mediator that allows heat transfer while blocking electromagnetic wave radiation, thus resolving the contradiction between heat radiation efficiency and electromagnetic wave interference.
2Temperature
If the heat sink size is increased to improve heat dissipation, then heat radiation performance is improved, but the heat sink acts as an antenna when larger than quarter wavelength, increasing electromagnetic interference
Solution Approach 1:
The electromagnetic wave absorption sheet serves as a protective intermediary that covers the heat sink surface. Even when the heat sink is large for effective heat dissipation, the absorption sheet prevents it from acting as an antenna by absorbing electromagnetic waves, thus eliminating the harmful effect while preserving the beneficial heat dissipation function.
3Temperature
If a conventional heat sink structure is used, then heat transfer is efficient, but electromagnetic wave absorption is insufficient
Solution Approach 1:
The solution employs a composite structure combining the heat sink (for thermal management) with an electromagnetic wave absorption sheet (for EMI reduction). This composite approach integrates two different material functions: one for heat conduction and another for electromagnetic wave absorption, thereby achieving both efficient heat transfer and sufficient electromagnetic wave absorption simultaneously.
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 reduces electromagnetic wave radiation from the heat sink, enhancing heat radiation characteristics and providing a robust measure against electromagnetic interference while maintaining efficient heat dissipation.
Implementation Method 1
a heat transfer member disposed between the heat spreader and the heat sink, and transmitting heat from the heat spreader to the heat sink
Implementation Method 2
a conductive member electrically connecting the heat spreader and the heat sink
Implementation Method 3
heat emitted from the heating component is transmitted to the heat sink via the heat transfer member and radiates through the heat sink
Data Source
AI summary
A heat radiation structure includes a heat spreader provided on a heating component mounted on a substrate, a heat sink disposed at a position facing the heat spreader, a heat transfer member disposed between the heat spreader and the heat sink, and transmitting heat from the heat spreader to the heat sink, and a conductive member electrically connecting the heat spreader and the heat sink.