PCB Recess for Via-Less Component Placement
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Solution Overview
Problem
High-speed printed circuit boards face challenges in efficiently using space due to signal vias, which degrade signal quality and reduce component density, as they require ground vias to mitigate impedance mismatches and cross-talk, but these vias occupy valuable space and complicate routing.
Innovation Solution
The solution involves creating a recess on the printed circuit board's surface to expose portions of the signal layer, allowing components like capacitors to be directly connected to the signal layer without signal vias, thereby reducing the need for ground vias and increasing component density by eliminating the space used by vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal vias are used to provide connectivity to internal layers, then signal connectivity is achieved, but component density is reduced and signal quality degrades due to loss and cross-talk
Solution Approach 1:
The patent extracts and eliminates the signal via from the traditional PCB structure by directly exposing the internal signal layer through a via-less recess. This removes the harmful via stub and associated ground vias, thereby improving signal quality while increasing component density by reclaiming the space previously occupied by via structures.
Solution Approach 2:
The patent transitions from a traditional planar surface-mount approach to a three-dimensional recessed mounting structure. By creating a recess that exposes the internal signal layer vertically, the design enables direct component connection to internal layers without requiring horizontal via pathways, thus improving both signal integrity and space utilization.
2Reliability
If ground vias are added to mitigate impedance mismatches and cross-talk, then signal quality improves, but usable space is reduced and routing becomes more complex
Solution Approach 1:
The patent removes the need for ground vias by eliminating the signal via structure that created impedance mismatches and cross-talk in the first place. The via-less recess design inherently provides better impedance control without requiring additional ground vias, thereby simplifying the routing structure while maintaining or improving signal quality.
3Ease of manufacture
If conventional surface mounting is used, then component placement is simple, but space utilization is inefficient due to via requirements
Solution Approach 1:
The patent introduces a vertical dimension by creating a recess that exposes the internal signal layer. This allows components to be mounted directly on the exposed signal layer within the recess, eliminating the need for signal vias and ground vias that would otherwise consume valuable surface area, thereby increasing usable space while maintaining manufacturing simplicity.
Data Source
AI summary
A printed circuit board (PCB) defines a first outer surface and a second outer surface that is opposite the first outer surface. The first outer surface of the PCB defines a recess. The PCB includes a signal layer between the first outer surface and the second surface with a first portion exposed within the recess and a second portion exposed within the recess. A component is disposed within the recess and connected to the first portion and the second portion of the signal layer such that an entirety of the component is within the recess and below the first surface.