PCB Connection Module With Reference Layer Through-Holes
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Solution Overview
Problem
It is challenging to design overlapping positions on a Printed Circuit Board (PCB) for both optical and electrical interfaces due to differing Electromagnetic Interference (EMI) radiation patterns caused by different operating frequencies, making it difficult to reuse these positions effectively.
Innovation Solution
The PCB incorporates a connection module with two signal layers and two reference layers, spaced apart, where each reference layer has a through-hole with an overlapping region with the connection module's projection, allowing for the reuse of reserved positions for optical and electrical interfaces while reducing EMI radiation through strategic hole placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If reserved positions for optical interface and electrical interface are overlapped on PCB, then versatility and reduction of mainboard types are improved, but EMI radiation control deteriorates due to different operating frequencies
Solution Approach 1:
The reference layer is segmented by creating through-holes at specific positions, dividing the continuous reference plane into separate regions. This segmentation allows different reference impedance zones to be created for optical and electrical interfaces simultaneously within the same overlapping area, enabling both interface types to coexist without EMI interference.
Solution Approach 2:
The patent applies local quality by creating through-holes with specific positioning relative to signal layers. The through-holes are strategically placed to provide local reference impedance adjustments in specific areas where optical and electrical interfaces overlap, while leaving other areas unchanged. This localized modification enables EMI control precisely where needed without affecting overall interface functionality.
2Object-affected harmful factors
If through-holes are added to reference layers to reduce EMI radiation, then EMI control is improved, but device complexity increases
Solution Approach 1:
The through-holes are designed and positioned in advance during the PCB layout phase, before actual signal transmission occurs. The hole positions are pre-calculated based on the overlapping regions of different interfaces and their respective EMI characteristics. This preliminary action allows EMI control to be built into the PCB structure from the beginning, avoiding the need for complex external EMI shielding or filtering components.
Data Source
AI summary
A PCB and a signal transmission system are provided. The PCB includes a connection module, and at least two signal layers and at least two reference layers spaced apart. The connection module comprises a first connection terminal and a second connection terminal. The first connection terminal is connected to at least one first signal layer and is connectable to an external optical interface. The second connection terminal is connected to at least one second signal layer and is connectable to an external electrical interface. Each reference layers is provided with a through-hole, and for each reference layers, there is an overlapping region between a projection region of an orthogonal projection of the connection module onto the reference layer and a hole region of the through-hole arranged on the reference layer.