Heat Conduction Sheet with Dual-Portion Structure for PCB Noise Reduction
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Solution Overview
Problem
Existing electronic devices with heat dissipation sheets experience increased undesired radiation noises due to dielectric polarization, leading to electromagnetic interference, and conventional shielding solutions enlarge the device size and component count.
Innovation Solution
A heat conduction sheet with a low relative dielectric constant portion and a high relative magnetic permeability portion is used, where the high permeability portion surrounds the low permeability portion and is positioned between the heat dissipation member and the electronic element, reducing electromagnetic coupling and noise emission without the need for additional shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat conduction member is provided between the metal plate for heat dissipation and the IC, then heat dissipation is improved, but undesired radiation noises increase
Solution Approach 1:
The heat conduction member is divided into two distinct portions: a first portion with high relative magnetic permeability and a second portion with low relative dielectric constant. Each portion is positioned to address specific interference mechanisms - the high permeability portion counteracts magnetic field coupling while the low dielectric constant portion reduces electric field coupling, thereby maintaining heat dissipation effectiveness while suppressing radiation noises
Solution Approach 2:
The heat conduction member functions as a composite structure combining materials with different electromagnetic properties. The first portion uses magnetic material characteristics to suppress magnetic coupling, while the second portion uses low dielectric constant material to suppress electric coupling. This composite approach enables simultaneous achievement of thermal management and electromagnetic noise reduction
2Object-generated harmful factors
If a shield case is used to shield undesired radiation noises, then electromagnetic interference is reduced, but the number of components and device size increase
Solution Approach 1:
The patent merges the heat conduction function and electromagnetic shielding function into a single integrated heat conduction member. This member simultaneously performs thermal management by conducting heat from the IC to the metal plate and electromagnetic interference suppression through its dual-portion structure. By combining multiple functions into one component, the total number of components is reduced and device size is minimized
Solution Approach 2:
The heat conduction member is designed as a multi-functional component that serves both thermal and electromagnetic purposes. It conducts heat from the IC to the metal plate for heat dissipation, while its specific structural configuration with different electromagnetic property portions provides shielding against both electric and magnetic field coupling. This universal design eliminates the need for separate shielding components
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 undesired radiation noises by minimizing electromagnetic coupling and energy loss, preventing device size enlargement and component increase, while maintaining effective heat dissipation.
Implementation Method 1
undesired radiation noises due to dielectric polarization
Implementation Method 2
high relative magnetic permeability portion is configured to surround the low relative dielectric constant portion
Implementation Method 3
heat conduction sheet... maintaining effective heat dissipation
Data Source
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Figure 3
AI summary
A printed circuit board (51) includes a printed wiring board (52) having a mounting surface (52a) facing a first side, an electronic element (53) provided on the mounting surface (52a), a heat dissipation member (57) disposed on the first side with respect to the electronic element (53), and a heat conduction member (54) disposed between the electronic element (53) and the heat dissipation member (57) and having a first surface (54b) facing the first side and a second surface (54a) facing a second side opposite to the first side. The heat conduction member (54) has a high relative magnetic permeability portion (56) and a low relative dielectric constant portion (55). The high relative magnetic permeability portion (56) surrounds the low relative dielectric constant portion (55) on at least the second surface (54a) of the heat conduction member (54). At least part of the low relative dielectric constant portion (55) overlaps the electronic element (53) in a plan view seen in a direction perpendicular to the mounting surface (52a).