Interlayer PCB Structure for 300 GHz Impedance Matching
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Solution Overview
Problem
Conventional circuit boards experience impedance mismatch and high reflection and insertion losses due to characteristic differences in the interlayer connective structure, affecting high-frequency signal integrity.
Innovation Solution
A circuit board device with a pad-free interlayer connective structure featuring a first interlayer connective structure with varying wall thickness and a second interlayer connective structure forming a ground path, surrounded by reference layers, to improve signal transmission quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interlayer connective structure is used, then manufacturing is simpler, but impedance mismatch and signal loss occur at high frequencies
Solution Approach 1:
The first pillar is designed with non-uniform wall thickness, where the first wall thickness at the end portions is greater than the second wall thickness at the central section. This local variation in geometric properties allows the structure to maintain impedance matching across different frequencies while using a relatively simple overall configuration.
2Reliability
If uniform wall thickness is used in the pillar, then manufacturing is easier, but impedance matching deteriorates at high frequencies
Solution Approach 1:
The pillar structure intentionally incorporates local quality variation through its non-uniform wall thickness distribution. The greater wall thickness at end portions and reduced wall thickness at the central section creates specific impedance characteristics that improve high-frequency signal transmission, accepting the increased manufacturing precision requirements as a trade-off for performance.
3Reliability
If reference layers are directly connected to the interlayer connective structure, then electrical connection is simpler, but signal loss increases
Solution Approach 1:
The reference layers are extracted from direct contact with the first interlayer connective structure, creating a separated configuration. This separation prevents the reference layers from interfering with the optimized impedance characteristics of the non-uniform pillar structure, thereby reducing signal loss while maintaining necessary electrical connections through the insulation portion.
Data Source
AI summary
A circuit board device for transmitting signals at a frequency of 50 GHz to 300 GHz is provided. The circuit board device includes an insulating portion, first and second interlayer conduction structures passing through the insulating portion, a first reference layer, and a second reference layer. The first interlayer conduction structure defines a signal path and includes a first pillar including first end portions and a first central section. The first thickness of the first end portions is greater than the second thickness of the first central section. The first and second reference layers are located on top and bottom surfaces of the insulating portion and surround the first interlayer conduction structure. Two opposite second end surfaces of the second interlayer conduction structure are respectively connected to the first reference layer and the second reference layer to define a ground path surrounding the signal path.