Multi-connection vias for printed circuit boards
Name
49632418-MIT.pdf
Description
Full printable version
Size
27.22 MB
Format
Adobe PDF
Checksum (MD5)
53f2248a45dec552a7af2cf20593733a
Author(s)
Kiani, Sepehr
Advisor(s)
Alexander H. Slocum.
Date Issued
1999
Publisher
Massachusetts Institute of Technology
Abstract
As the performance of digital electronic components improves, maintaining the integrity of high-frequency signals through circuit boards becomes increasingly challenging. The dimensions and material parameters of in-plane circuit board features, such as striplines, microstrips and co-planar waveguides are tuned to control signal impedance. Conventional multi-layer vertical interconnects, which connect between board layers, are not impedance matched to the in-plane signal traces. Multi-connection vias, developed in this thesis, provide a method for matching the impedance of vertical and in-plane features by forming co-cylindrical waveguides. Solutions from a high-frequency full-wave solver provide insight into field interactions within multi-connection vias; and results from these simulations and signal integrity experiments indicate impedance "tuneability" by adjusting the multi-connection via dimensions. The results also suggest that features can be impedance-matched independent of via diameter. Multi-connection vias are formed by creating distinct conductor paths within cylindrical plated through-holes. The thesis explores several alternative manufacturing methods for fabricating these features. A specialized broaching machine and carbide-insert broaches were used to manufacture multi-connection vias for signal integrity experiments. Models of the broach tool and cutting force simulations resulted in several iterations of the broach design.
(cont.) Broaching multi-connection vias is challenging due to the small diameters and high aspect ratios of plated through-holes, as well as the unique copper-epoxy/resin material. Since the broaching process prefers larger plated through-holes to permit larger broach tools, a new method was developed to analyze the cumulative connection density of multi-connection via arrays. Multi-connection vias provide fertile ground for the development of corollary electronic products. Simulations for connector launches indicate that via impedance control can extend to board-mounted devices and connectors. Products that may benefit from multi-connection vias include by-pass capatrs, IC packages, test probes and pogo pins. The thesis presents a road map for commercializing multi-connection vias. Elements of the roadmap ... integration of new signal routability constraints in CAD/CAM software, manufacturing processes, machine tool design, board testing, and durability.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.
Includes bibliographical references (p. 182-184).
Subjects
Mechanical Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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