PCB Paddle Card Cavity Layout for Twinax Impedance and Shielding
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Solution Overview
Problem
Paddle cards in existing information handling systems suffer from varying signal trace impedances and require significant space for twinax cable connections, which affect shielding and efficiency.
Innovation Solution
A paddle card design with a printed circuit board featuring a cavity to expose signal pads, coupled with a twinax cable and an electromagnetic interference (EMI) shield connected to a ground pad, optimizing cable placement and reducing impedance by eliminating separate ground pads and using a common EMI shield for multiple cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate ground pads are used for each twinax cable connection, then signal trace impedance control is improved, but space utilization increases and device complexity increases
Solution Approach 1:
The patent merges multiple separate ground pads into a single common ground pad that serves all twinax cable connections. This consolidation reduces the number of discrete ground pad elements while maintaining proper impedance control through the cavity structure and EMI shield design, thereby reducing space utilization without sacrificing manufacturing precision.
Solution Approach 2:
The common ground pad is designed to perform multiple functions simultaneously: it provides ground reference for all twinax cables, serves as a reference plane for impedance control, and works in conjunction with the EMI shield to provide electromagnetic interference protection. This multi-functionality eliminates the need for separate ground pads for each cable.
2Manufacturing precision
If separate ground pads are used for each twinax cable connection, then signal trace impedance control is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple separate ground pads into a single common ground pad that serves all twinax cable connections. This consolidation reduces the number of discrete ground pad elements while maintaining proper impedance control through the cavity structure and EMI shield design, thereby reducing space utilization without sacrificing manufacturing precision.
Solution Approach 2:
The common ground pad is designed to perform multiple functions simultaneously: it provides ground reference for all twinax cables, serves as a reference plane for impedance control, and works in conjunction with the EMI shield to provide electromagnetic interference protection. This multi-functionality eliminates the need for separate ground pads for each cable.
3Ease of manufacture
If traditional paddle card design is used, then ease of manufacture is maintained, but shielding effectiveness decreases due to cable placement requirements
Solution Approach 1:
The patent embeds the twinax cable connections within a cavity structure in the PCB, effectively nesting the cables within the board thickness. This allows the EMI shield to be positioned directly over the cavity, creating a nested configuration where the shield encompasses the cable connections, thereby improving shielding effectiveness while maintaining ease of manufacture through standard PCB fabrication processes.
Solution Approach 2:
The patent transitions from a planar cable placement approach to a three-dimensional configuration by utilizing a cavity in the PCB. This vertical dimension allows the EMI shield to be positioned above the cable connections, creating effective shielding without requiring additional horizontal space, thus maintaining ease of manufacture while improving shielding effectiveness.
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 design improves signal trace impedance control and reduces space utilization while enhancing shielding, resulting in more efficient and compact paddle card configurations.
Implementation Method 1
an electromagnetic interference (EMI) shield. The PCB may include a first metal layer on a top surface of the PCB, a second metal layer within the PCB, and a cavity in the top surface of the PC. The cavity may expose the second metal layer. The first metal layer may include a ground pad. The second metal layer may include a signal pad located within the cavity. The shielded cable may include a signal conductor coupled to the first signal pad. The EMI shield may be coupled to the ground pad and covers the cavity.
Data Source
AI summary
A paddle card includes a printed circuit board (PCB), a shielded cable, and an electromagnetic interference (EM) shield. The PCB includes a first metal layer on a top surface of the PCB, a second metal layer within the PCB, and a cavity in the top surface of the PC. The cavity exposes the second metal layer. The first metal layer includes a first ground pad. The second metal layer includes a signal pad located within the cavity. The shielded cable includes a signal conductor coupled to the first signal pad. The EMI shield is coupled to the ground pad and covers the cavity.