PCB Ground Pattern Segmentation for Crosstalk and Bridging
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Solution Overview
Problem
Variations in the area of connection parts on circuit boards due to inaccuracies in the formation of insulating layers can affect the reliability and electrical characteristics of connections, particularly in high-density mounting applications like optical modulators, leading to issues with crosstalk and solder bridging.
Innovation Solution
The circuit board design separates ground patterns into connection and wiring ground patterns, with the connection ground patterns being exposed and the wiring ground patterns covered with solder resist, ensuring uniform connection areas and preventing solder bridging, while maintaining impedance matching and reducing crosstalk through strategic spacing and layering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the non-connection part is covered with the insulating layer to prevent solder bridging, then solder bridging is prevented, but the connection part area varies due to formation accuracy variations
Solution Approach 1:
The ground pattern is divided into two distinct segments: a connection part for soldered connection and a non-connection part for crosstalk reduction. The insulating layer is applied only to the non-connection part, separating the functions of connection and insulation to eliminate area variation while preventing solder bridging.
Solution Approach 2:
The insulating layer is applied locally only to the non-connection part of the ground pattern, not the entire ground pattern. This local application ensures that the connection part area remains uniform and accessible for soldering while the non-connection part is protected from solder bridging.
2Object-affected harmful factors
If multiple ground patterns are formed on the surface to reduce crosstalk, then crosstalk is reduced, but the complexity of the circuit board increases
Solution Approach 1:
Each ground pattern is segmented into connection and non-connection parts with distinct functions. The connection part facilitates soldered connection while the non-connection part reduces crosstalk, allowing multiple ground patterns to be effectively managed without proportionally increasing overall complexity.
Solution Approach 2:
The ground pattern design serves multiple functions simultaneously: the connection part provides soldered connection to another circuit board, the non-connection part reduces crosstalk, and the insulating layer prevents solder bridging. This multi-functionality reduces the need for additional separate structures.
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 design stabilizes connection part areas, enhances mountability, reduces crosstalk, and improves manufacturing reliability by preventing solder bridging and maintaining consistent impedance, enabling high-density mounting and efficient signal transmission.
Implementation Method 1
a non-connection part is covered with an insulating layer, such as a solder resist, to prevent a short circuit due to solder bridging
Implementation Method 2
Each of the ground patterns is coupled to another circuit board and serves to reduce crosstalk
Implementation Method 3
a non-connection part is covered with an insulating layer, such as a solder resist, to prevent a short circuit due to solder bridging
Data Source
AI summary
A printed circuit board (PCB) has a connection ground pattern and a wiring ground pattern. The connection ground pattern is a pattern for soldered connection formed on a first wiring layer. The wiring ground pattern is formed to be spaced from the connection ground pattern on the first wiring layer. The connection ground pattern and the wiring ground pattern are electrically coupled via a second wiring layer. When the wiring ground pattern is covered with an insulating layer, such as a solder resist, even if the position of an end of the insulating layer varies among wiring ground patterns, an influence on an exposed area of the connection ground pattern is eliminated.