Periodically Patterned Heatsink EMI Reduction
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Solution Overview
Problem
High-speed integrated circuits (ICs) emit electromagnetic radiation that interferes with other components due to the heatsink acting as an efficient antenna, and existing solutions like decoupling capacitors, series resistors, and shielding add cost and consume space on circuit boards.
Innovation Solution
A heatsink with a periodically patterned structure of electrically and thermally conductive patches interconnected by narrow branches, forming an electromagnetic bandgap (EBG) structure with thermally conductive but electrically non-conductive fillers and fins, which reduces electromagnetic interference without compromising heat dissipation or affordability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional solid heatsink base is used, then heat dissipation is effective, but electromagnetic interference propagates efficiently due to the large metallic surface area acting as an antenna
Solution Approach 1:
The heatsink base is segmented into a periodic array of conductive patches separated by non-conductive gaps. This segmentation disrupts the continuous metallic surface that acts as an antenna for EMI, while maintaining thermal conduction paths through the patches and their interconnecting structures
Solution Approach 2:
Different regions of the heatsink base have different electrical properties: the conductive patches provide both thermal and electrical conduction, while the gap regions provide thermal conduction paths with electrical isolation. This local differentiation allows simultaneous EMI reduction and heat dissipation
2Object-affected harmful factors
If shielding components such as RF gaskets are added to reduce EMI, then electromagnetic interference is reduced, but cost and space consumption on the circuit board increase
Solution Approach 1:
The heatsink base is designed to perform multiple functions simultaneously: heat dissipation through thermal conduction and EMI reduction through its periodic structure. This eliminates the need for separate shielding components like RF gaskets, reducing both cost and device complexity
Solution Approach 2:
The EMI shielding function is merged with the heat dissipation function by integrating the periodic conductive patch structure directly into the heatsink base. This combination 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
The periodically patterned heatsink effectively diminishes electromagnetic noise propagation in specific frequency bands, comparable to conventional heatsinks in terms of heat dissipation and cost, while maintaining electrical properties and thermal conductivity.
Implementation Method 1
A first embodiment is a heatsink for an integrated circuit incorporating a periodically patterned structure within a base of the heatsink. The periodically patterned structure, together with a solid metal layer of a circuit board, form an electromagnetic bandgap structure that reduces the efficiency of the heatsink acting as an antenna in certain frequency bands.
Implementation Method 2
The periodically patterned structure includes a periodic array of electrically-conductive patches interconnected by electrically-conductive branches. The patches and branches collectively form a thermally conductive pathway from the integrated circuit to the cooling fins.
Data Source
AI summary
A heatsink including an electromagnetic bandgap structure reduces electromagnetic interference caused by an integrated circuit in an electronic device. One embodiment provides a heatsink having a base with an array of electrically-conductive, thermally-conductive patches spaced apart in two dimensions of a reference plane and having a thickness perpendicular to the reference plane. The patches are interconnected by a plurality of branches. Each branch connects adjacent patches and has a width in the reference plane of less than a width of each adjacent patch. A plurality of thermally conductive cooling fins coupled to a surface of the base and extend normal to the reference plane. The cooling fins may be formed of a thermally-conductive, electrically non-conductive material or may be coupled to the base by a thermally-conductive, electrically non-conductive material. The periodically patterned structure of the base, together with a solid metal layer of a circuit board, form an electromagnetic bandgap structure that reduces certain frequencies of electromagnetic noise caused by the integrated circuit.