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Design and Method for Automated Differential Impedance Measurements on IC Packages

IP.com Disclosure Number: IPCOM000007242D
Publication Date: 2002-Mar-06
Document File: 3 page(s) / 43K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for measuring the differential impedance of many sets of differentially routed pairs of traces. Benefits include the ability to conduct a large number of measurements in a short period of time.

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Design and Method for Automated Differential Impedance Measurements on IC Packages

Disclosed is a method for measuring the differential impedance of many sets of differentially routed pairs of traces. Benefits include the ability to conduct a large number of measurements in a short period of time.

Background

Currently, measurements are done manually with a bench-top meter and probe micromanipulators. This method, though effective, is very time intensive.

General Description

The disclosed method automates the process of measuring differential impedance. The disclosed method proposes two different implementations of this process:

1.      The first implementation uses two independent probing arms, each with four degrees of positional freedom (x, y, z, and theta) that accept two commercially available RF probes (see Figure 1). The two probes contact neighboring sets of C4 bumps to perform the differential TDR measurements. To contact a variety of bump configurations, the two probe positioning assemblies are independent.
The camera which aligns and determines the position of the probes rotates on the same axis as one of the probes (see Figure 1). The camera and the associated image processing allows the system to establish the position of probes, recognize the desired test locations, and adjust the positions of both probes as necessary. The probe assembly without the camera is located far enough away from the probe assembly with the camera so that the probes contact neighboring C4 bum...