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Method for a measurement technique for extracting package inductance

IP.com Disclosure Number: IPCOM000007592D
Publication Date: 2002-Apr-08
Document File: 5 page(s) / 65K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a measurement technique for extracting package inductance. Benefits include improved productivity and improved reliability.

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Method for a measurement technique for extracting package inductance

Disclosed is a method for a measurement technique for extracting package inductance. Benefits include improved productivity and improved reliability.

Background

              Conventionally, no reliable method exists for measuring the package contribution of the total inductance to package decoupling capacitors. The determination of this inductance is an importance element in both package design and predictive modeling. The requirement for low inductance is a primary driver for new package technology. Inductance requirements also govern requirements for capacitors. The conventional inductance measurement techniques provide the inductance of a package coupled with the inductance of a secondary element, a capacitor.

              Conventional inductance measurements include two options:

§         Total inductance of the capacitor and package

§         Inductance of the capacitor only using specialized fixtures

              Measured inductance is the addition of the capacitor and package (see Figure 1). The inductive loop measured is indicated by a dashed line. The capacitor is a crucial element in the measurement. The capacitor has a resonance frequency in the range of interest. The resonance frequency of the package alone is much higher than the resonance frequency of the capacitor and package assembly. Without the capacitor assembled, the resonance frequency of the package is so high that we cannot assume the characteristics are equivalent at lower frequencies.

Figure 5.  Package and capacitor inductive loop.

Figure 6 illustrates the current method to measure the inductance of a capacitor.  A specialized fixture must be designed and built to measure the inductance. 

Description

              The disclosed method is a measurement technique that yields the inductance of a package. The disclosed technique outlines a procedure to eliminate the inductance contribution of the secondary element included in conventional methods.

              The key elements required for measurement are:

§         A package containing an interconnect to a capacitor

§         A capacitor with more than 4 terminals

Advantages

              With the new measurement technique, inductance of various package technologies and designs can be directly compared through measurements. The result is improved productivity and improved reliability.

Detailed description

      The disclosed method includes a technique for measuring inductance and can be implemented using the following steps:

1.           Identification of a capacitor with more than 4 terminals.

2.           Layout the design, including capacitor pads, probe pads, and a connection scheme.

3.           Fabri...