Air-Filled Transmission Line Via Structure for High-Aspect Ratio Routing
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Solution Overview
Problem
Existing transmission line via structures in semiconductor devices often require solid dielectric materials, which limit the size reduction of vias and hinder efficient routing on printed circuit boards, especially for high-frequency signals.
Innovation Solution
A transmission line via structure is developed using a coaxial design with dielectric support members and sacrificial material, where the volume between these members is filled with air, allowing for reduced size vias and improved routing by stacking sub-structures with conductive paste and removing sacrificial material to create a non-solid dielectric structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If solid dielectric material is used in transmission line via structures, then the via structure provides mechanical support and electrical insulation, but the via size and aspect ratio are restricted leading to increased PCB real estate requirements
Solution Approach 1:
The patent uses air as a porous/void dielectric material between the center conductor and outer ground conductor, replacing traditional solid dielectric materials. This air-filled space provides electrical insulation while allowing for smaller via dimensions and higher aspect ratios, thereby reducing PCB real estate requirements without compromising signal propagation continuity.
Solution Approach 2:
The patent changes the dielectric parameter from solid material to air (void space), which has different electrical properties including lower dielectric constant. This parameter change enables the via structure to achieve the same electrical insulation function with reduced physical dimensions, allowing for compact via designs that conserve PCB space while maintaining reliable high-frequency signal transmission.
2Shape
If solid dielectric material is used in transmission line via structures, then the via structure maintains structural integrity, but the via size is restricted preventing high aspect ratio vias
Solution Approach 1:
The air-filled void space between conductors replaces solid dielectric, enabling high aspect ratio via geometries. The outer ground conductor and center conductor provide structural framework that maintains integrity while the air space allows for extended via length relative to diameter, achieving high aspect ratios that would be impossible with solid dielectric materials.
Solution Approach 2:
The transmission line via structure uses a composite configuration combining conductive materials (center conductor, outer ground conductor, conductive paste) with air as the dielectric medium. This composite structure leverages the mechanical strength of the conductive components while using air to enable high aspect ratio geometries, achieving both structural integrity and desired shape characteristics.
3Productivity
If traditional solid dielectric via structures are used, then the via provides electrical insulation, but routing efficiency is reduced due to larger via size requirements
Solution Approach 1:
The air-filled dielectric space enables significantly smaller via footprints compared to solid dielectric materials. This size reduction allows for higher via density on PCBs, improving routing efficiency by enabling more signal paths within the same area and allowing closer spacing between adjacent vias and traces.
Solution Approach 2:
By changing the dielectric parameter from solid material to air, the via dimensions can be reduced while maintaining electrical insulation performance. This parameter change directly reduces via size, enabling more efficient PCB routing with higher via density and better space utilization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the formation of high-aspect ratio vias with a center-to-diameter ratio greater than 30:1, reducing PCB real estate and minimizing discontinuities in signal transmission, thus enhancing routing efficiency for high-frequency signals.
Implementation Method 1
Conductive paste is disposed between the center and outer conductor portions of successive ones of the plurality of sub-structures to form an outer conductor and a center conductor
Implementation Method 2
The dielectric support member(s) separate the outer conductor portion and the center conductor portion and provide a non-solid volume between the outer conductor portion and the center conductor portion
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
In a transmission line via structure, a plurality of sub-structures (406) are stacked in a via (401 ) through the substrate (402) along a longitudinal axis thereof. Each of the sub-structures includes a center conductor portion (410), an outer conductor portion (412), and at least one dielectric support member (210). The center conductor portion extends along the longitudinal axis. The outer conductor portion is disposed around the center conductor portion. The dielectric support member(s) separate the outer conductor portion and the center conductor portion and provide a non-solid volume (214) between the outer conductor portion and the center conductor portion. Conductive paste (408) is disposed between the center and outer conductor portions of successive ones of the plurality of sub-structures to form an outer conductor and a center conductor.