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Method of Non-Invasively Measuring High Speed Signals in a Land Grid Array (LGA) Field

IP.com Disclosure Number: IPCOM000200695D
Publication Date: 2010-Oct-25
Document File: 3 page(s) / 77K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method is provided to temporarily replace a Land Grid Array (LGA) contact array with a structure that allows non-invasive measurement of high speed signals in an LGA field. The structure includes a tri-layer sandwich of a first self-aligning high performance contact array, a thin fan-out membrane, and a second self-aligning high performance contact array.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

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Method of Non-Invasively Measuring High Speed Signals in a Land Grid Array (LGA) Field

Disclosed is a method disclosed for temporarily replacing an LGA contact array with a structure for non-invasive measurement of high speed signals in an LGA field.

Typically, high performance computing platforms utilize a Land Grid Array (LGA) to interface high density, high speed chip modules with a processor Printed Circuit Board (PCB) . LGA is a mechanical assembly essential for maintaining thermal cooling and electrical contact integrity of an LGA contact array . However, the LGA assembly precludes ready access to high speed signal traces or to monitor noise on the power nets . The signals need to be accessed for debugging during initial stages of system bring-up where sources of failure need to be identified.

Fig. 1 illustrates conventional Via Construction and Internal PCB Configuration . In order to access high speed signal traces (shown in blue in Fig. 1) or to monitor noise on the power nets (shown in red in Fig. 1), holes are to be drilled into the back pressure plate and probes inserted into the resulting holes . The probes need to be custom designed for avoiding loading of the power nets.

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Figure 1

The method disclosed herein, temporarily replaces the LGA contact array with a structure that allows non-invasive measurement of high speed signals in an LGA field . The structure includes a tri-layer sandwich of a first self-aligning high performance contact array, a thin fan-out membrane, and a second self-aligning high performance contact array . The thin fan-out membrane incorporates passive elements for buffering

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signal sense lines from "through vias" in a single tap membrane . Fig. 2 illustrates the LGA contact array replaced with the structure disclosed herein.

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Figure 2

Fig. 3 illustrates an enlarged view of self-aligning contacts and embedded passives in a signal tap membrane . The self-aligning contacts include an array of floating vertical columns arrayed on a smaller pitch than that of the...