Circuit Structure Impedance Matching via Via Pad Spacing
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Solution Overview
Problem
In high-speed and high-frequency signal transmission, existing conductor designs often suffer from impedance mismatch, leading to significant reflection and insertion loss, which degrades signal quality.
Innovation Solution
A circuit structure with specific configurations, including differential pairs and strategically positioned through holes and ball grid array pads, along with a ground via, is designed to achieve impedance matching and reduce signal interference, enabling effective transmission of signals within the 1 GHz to 30 GHz frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductor designs are used for signal transmission, then the structure is simple and easy to manufacture, but impedance mismatch occurs causing significant reflection and insertion loss
Solution Approach 1:
The conductor structure is segmented into multiple components: line segments, through holes, ball grid array pads, and ground vias. Each segment serves a specific function in maintaining impedance matching and reducing signal interference, thereby improving signal transmission quality without requiring complete redesign of the entire conductor system.
Solution Approach 2:
Through holes and ground vias act as intermediary elements between line segments and ball grid array pads. These intermediaries facilitate impedance matching by providing controlled transition paths for signals and establishing reference planes, thus reducing reflection and insertion loss while maintaining manageable structural complexity.
2Reliability
If the first through hole and second through hole are positioned with specific spacing, then signal interference is reduced and return loss improves, but the design and manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by positioning through holes and ball grid array pads with specific spacing relationships in critical areas. The first distance between corresponding through holes is made less than the second distance between ball grid array pads, creating localized impedance matching zones that reduce signal interference while allowing other areas to have more relaxed dimensional tolerances.
3Reliability
If ground via is added between signal lines, then electromagnetic interference is reduced and signal integrity improves, but the manufacturing process becomes more complex
Solution Approach 1:
The ground via is merged with the existing conductor structure, sharing the same fabrication process steps for through hole formation and plating. This integration approach allows the ground reference to be established without adding separate manufacturing operations, thus improving signal integrity while minimizing increases in manufacturing complexity.
Data Source
AI summary
A circuit structure including a first signal line and a second signal line is provided. The first signal line includes a first line segment, a first ball grid array pad, and a first through hole disposed between the first line segment and the first ball grid array pad. The second signal line includes a second line segment, a second ball grid array pad, and a second through hole disposed between the second line segment and the second ball grid array pad. In a plan view, a line connecting the center of the first ball grid array pad and the center of the second ball grid array pad has a first distance, a line connecting the center of the first through hole and the center of the second through hole has a second distance, and the first distance is less than the second distance. A chip package is also provided.