High-Frequency Circuit Shield Layout for EMI Leakage and Strength
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Solution Overview
Problem
High-frequency circuits face a challenge in preventing electromagnetic wave leakage while maintaining structural strength, as the formation of shield vias through holes in the substrate can weaken the circuit and allow unnecessary electromagnetic waves to radiate, affecting peripheral circuits.
Innovation Solution
A high-frequency circuit design featuring a multilayer structure with elongated holes in the dielectric layers that do not extend through the ground pattern, surrounded by electromagnetic wave shields with ground electric conductors on the inner surfaces of these holes, effectively preventing electromagnetic wave leakage while minimizing strength reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shield vias are formed through holes in the dielectric substrate to prevent electromagnetic wave leakage, then electromagnetic wave shielding is improved, but the structural strength of the circuit is reduced
Solution Approach 1:
The shield via structure is segmented into two separate parts: a first ground electric conductor in the first dielectric layer and a second ground electric conductor in the second dielectric layer. These segmented conductors are electrically connected to the ground pattern but do not extend through the entire ground pattern, thereby preventing complete structural disruption while maintaining electromagnetic shielding effectiveness.
Solution Approach 2:
The shield vias are configured with local quality by limiting their extension to specific dielectric layers rather than penetrating the entire ground pattern. The first and second ground electric conductors are positioned in respective dielectric layers and connected to ground patterns locally, providing targeted electromagnetic shielding while preserving the overall structural integrity of the circuit.
2Object-generated harmful factors
If through-holes are formed to create electromagnetic wave shields, then electromagnetic wave radiation is reduced, but the circuit structure becomes weaker
Solution Approach 1:
The shielding structure is divided into segmented components located in different dielectric layers. The first ground electric conductor in the first dielectric layer and the second ground electric conductor in the second dielectric layer work together to suppress electromagnetic wave radiation without requiring a continuous through-hole that would compromise structural strength.
Solution Approach 2:
The shielding approach transitions from a vertical through-hole configuration to a layered horizontal configuration. By placing ground electric conductors in separate dielectric layers and connecting them to ground patterns, the solution addresses electromagnetic radiation in the horizontal plane while preserving vertical structural integrity.
Data Source
AI summary
A high-frequency circuit includes a first dielectric layer, a circuit layer, a second dielectric layer arranged in this order, the circuit layer includes a transmission line of a high-frequency signal and a ground pattern disposed around the transmission line. An electromagnetic wave shield is disposed in the first dielectric layer and the second dielectric layer around the transmission line. The electromagnetic wave shield includes a first ground electric conductor formed on an inner surface of at least one first hole formed to extend through the first dielectric layer without extending through the ground pattern, and a second ground electric conductor formed on an inner surface of at least one second hole formed to extend through the second dielectric layer without extending through the ground pattern. The first ground electric conductor and the second ground electric conductor are each electrically connected to the ground pattern.