Variable-Thickness PCB Transmission Lines for 224 Gbps Signal Integrity
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Solution Overview
Problem
The challenge of improving signal integrity and increasing bandwidth in high-speed printed circuit boards, particularly for 224 Gbps chips, is exacerbated by the need to maintain reliable signal transmission with smaller pin pitches, such as 0.6 mm, without increasing manufacturing difficulty.
Innovation Solution
The printed circuit board design incorporates transmission lines with varying thicknesses in different regions, specifically a thinner first thickness in the inter-layer signal transmission region and a thicker thickness in other regions, with the first thickness being less than or equal to a preset threshold, typically 0.5 OZ copper foil, to accommodate smaller pin pitches while ensuring signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pin pitch is reduced to 0.6 mm for 224 Gbps chips, then the bandwidth and signal transmission capability are improved, but the manufacturing difficulty and reliability risks increase due to the need to lay out 2/2 mil ultra-fine differential signal lines
Solution Approach 1:
The patent applies local quality by making the transmission line thickness non-uniform: the first thickness in the inter-layer signal transmission region is smaller than the second thickness in other regions. This localized thinning in specific regions allows ultra-fine signal lines to be laid out without affecting overall manufacturing feasibility, thus resolving the contradiction between high-speed transmission requirements and manufacturing difficulty.
2Area of stationary object
If the pin pitch is reduced to 0.6 mm, then the space utilization is improved, but the signal integrity deteriorates due to increased difficulty in maintaining reliable signal transmission
Solution Approach 1:
The transmission line thickness is locally optimized: thinner in the inter-layer signal transmission region (first thickness) to accommodate smaller pin pitches and improve space utilization, while thicker in other regions (second thickness) to maintain signal integrity and transmission reliability. This resolves the contradiction between space utilization and signal reliability.
3Reliability
If uniform thick transmission lines are used throughout the PCB, then the signal transmission reliability is maintained, but the space requirements increase preventing achievement of 0.6 mm pin pitch
Solution Approach 1:
The patent implements variable thickness transmission lines where the first thickness in the inter-layer signal transmission region is reduced to enable 0.6 mm pin pitch accommodation, while the second thickness in other regions maintains signal transmission reliability. This local differentiation resolves the contradiction between reliability and space requirements.
Data Source
AI summary
There is provided a printed circuit board, including a layer structure body and a transmission line for transmitting signals. The transmission line is located in the layer structure body. The layer structure body includes a first region and a second region. The first region is a region for inter-layer signal transmission in the layer structure body, and the second region is a region other than the first region. The transmission line has a first thickness in the first region and a second thickness in the second region, and the first thickness is less than the second thickness, and less than or equal to a first preset threshold. An electronic device and a method for manufacturing a printed circuit board are further provided.