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Measuring Leak Rates of Component Packages

IP.com Disclosure Number: IPCOM000076453D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Corl, EA: AUTHOR [+3]

Abstract

This method allows measurement of leak rates of component packages when the leak rates are too large for quantitative measurement by the helium leak test method, and when the bubble test method gives only qualitative results. The range of quantitative measurements of this method is from about 2 x 10/-6/ cc/sec to about 3 x 10/-4/cc/sec. The measurement is made with a vacuum microbalance sensitive to weight changes of about 2 micrograms.

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Measuring Leak Rates of Component Packages

This method allows measurement of leak rates of component packages when the leak rates are too large for quantitative measurement by the helium leak test method, and when the bubble test method gives only qualitative results. The range of quantitative measurements of this method is from about 2 x 10/-6/ cc/sec to about 3 x 10/-4/cc/sec. The measurement is made with a vacuum microbalance sensitive to weight changes of about 2 micrograms.

A component package similar to those to be tested is opened so as to expose its internal volume. This is used as a reference component. Its weight is compared with the weight of the component to be tested, first in air at one atmosphere, then as a function of time in vacuum. The initial relative weight in air establishes a reference level. When the microbalance is first evacuated, the apparent relative weight gain of the component under test (due to loss of buoyancy) gives a measure of its internal volume. The rate of relative weight loss with time in vacuum is proportional to the leak rate.

The method may be made more sensitive by first placing the component to be tested in a chamber containing gas at elevated pressure. The quantitative relation between rate of weight change and leak rate then depends on the density of the specific gas used for testing.

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