Printed Wiring Board Signal Transmission Substrate Segmentation
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Solution Overview
Problem
Conventional printed wiring boards face challenges in simultaneously transmitting low-speed and high-speed signals efficiently due to differences in signal attenuation rates and characteristic impedance, leading to issues like warping and increased substrate size.
Innovation Solution
A printed wiring board design featuring a packaging substrate with a pad group for low-speed signals and a separate transmission substrate with horizontal and vertical wirings for high-speed signals, where the transmission substrate includes first and second pads connected by horizontal wiring to reduce signal attenuation and prevent warping, while maintaining a consistent characteristic impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single substrate is used to transmit both low-speed and high-speed signals, then device complexity is reduced, but signal attenuation increases and manufacturing precision becomes difficult to maintain
Solution Approach 1:
The substrate is divided into two distinct parts: a packaging substrate for mounting electronic components and a transmission substrate for high-speed signal transmission. This segmentation allows each substrate to be optimized for its specific function, with the transmission substrate designed with controlled impedance for high-speed signals while the packaging substrate handles low-speed signals and component mounting, thereby resolving the contradiction between device simplicity and signal transmission quality.
Solution Approach 2:
Different regions of the overall substrate system are given different properties: the packaging substrate region is optimized for component mounting and low-speed signals, while the transmission substrate region is optimized with specific impedance control for high-speed signals. This local differentiation allows each region to perform its function optimally without compromising the other.
2Reliability
If the substrate size is increased to accommodate both signal types, then signal transmission quality improves, but device dimensions increase
Solution Approach 1:
The transmission substrate is positioned in a different spatial dimension relative to the packaging substrate, mounted on the peripheral portion rather than occupying the same planar space. This dimensional arrangement allows high-speed signal transmission paths to be established without increasing the overall footprint, as the transmission substrate utilizes the peripheral area efficiently.
3Reliability
If different impedance designs are used for different signal types, then signal transmission quality improves, but device complexity increases
Solution Approach 1:
The substrate system is segmented into two independent substrates, each with its own impedance design optimized for its specific signal type. The transmission substrate is designed with controlled impedance for high-speed signals, while the packaging substrate uses conventional impedance for low-speed signals. This segmentation eliminates the need for complex multi-impedance design within a single substrate.
Data Source
AI summary
A printed wiring board has a packaging substrate having multiple pads, and a transmission substrate mounted on the multiple pads of the packaging substrate. The packaging substrate has a pad group constituted of pads which mount an electronic component, the multiple pads mounting the transmission substrate includes a first pad positioned in a peripheral portion of the packaging substrate and a second pad positioned between the first pad and the pad group, the second pad is electrically connected to a signal pad of the pads in the pad group, and the transmission substrate includes a horizontal wiring which electrically connects the second pad and the first pad and which transmits a signal between the second pad and the first pad.