Browse Prior Art Database

Coaxial Probe and Zo Detector

IP.com Disclosure Number: IPCOM000089688D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Deskur, KJ: AUTHOR

Abstract

Characteristic impedance Zo can be measured by time domain reflectometry (TDR). Probe 10 and detector 20 are useful for TDR testing in printed-circuit (PC) board manufacturing.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 63% of the total text.

Page 1 of 2

Coaxial Probe and Zo Detector

Characteristic impedance Zo can be measured by time domain reflectometry (TDR). Probe 10 and detector 20 are useful for TDR testing in printed-circuit (PC) board manufacturing.

Probe 10 of Fig. 1 is a conventional coaxial circuit probe. It has a spring- loaded center conductor 11 that is axially movable relative-to, and dielectrically coupled-with, outer concentric conductor shell 12. Collar or flange member 13 has an upper metallic ring 14 and lower conductive rubber backing ring 15. Member 13 is concentrically affixed and electrically connected to the end 16 of shell 12.

In operation, tip 11A of conductor 11 is placed on the connection, e.g., a plated through hole (PTH) or pin, of the PC line of a PC board (not shown) to be tested, for example, for its characteristic impedance Zo, by TDR. Probe 10 is pushed down until member 13 makes contact with the surface of the PC board. As a result, the nearest PC ground pad or ground pin of the board, within the contact area of 13, contacts member 13. Vee-notch 17 allows visual observation of conductor tip 11A to facilitate its application to the PTH or pin of the tested PC line. Thus, probe 10 is particularly advantageous as a TDR probe as its flange 13 allows the shortest possible connection between probe 10 and the ground connection, which is not always easily identifiable on the board.

Detector 20 (Fig. 2), using TDR, measures the Zo of a ground wire 21, which is connected in parallel to...