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Ionic Measurement Gauge

IP.com Disclosure Number: IPCOM000113028D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 212K

Publishing Venue

IBM

Related People

Brand, JL: AUTHOR [+3]

Abstract

Ionic contamination leads to device failure in computers and disk drives. An improved instrument has been developed which provides a safe, sensitive, accurate, repeatable, user friendly, and cost effective gauge instrument to measure and quantify ionic contamination on parts.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 25% of the total text.

Ionic Measurement Gauge

      Ionic contamination leads to device failure in computers and
disk drives.  An improved instrument has been developed which
provides a safe, sensitive, accurate, repeatable, user friendly, and
cost effective gauge instrument to measure and quantify ionic
contamination on parts.

      A commercially available instrument used to measure ionic
contamination was located and purchased.  This instrument was the
500M Ionograph; manufactured and distributed by the original
equipment manufacturer (OEM) Alpha Metals, Incorporated.

      The OEM Ionograph measures ionic contamination by immersing the
sample into a small cell (holding chamber) that is filled with a
solution of 75% isopropyl alcohol and 25% deionized water.  Ionic
contamination on the sample is extracted (dissolved) by the alcohol
and water solution (extract) and forms electrical conducting ions
that cause a change in the conductivity of the extract.  During
sample testing, the instrument measures the change in conductivity of
the extract over a period of time.  By analogue to a known
calibration standard, the instrument interprets the change in
conductivity as being caused by the presence of a certain equivalent
amount of sodium chloride.  Integration over a period of time of the
change in conductivity is reported to the operator in terms of
micrograms of sodium chloride on the sample.   To complete the
process, the ions are removed from the alcohol-water extract mixture
by passing the solution through a deionization bed and the
"deionized" solution is returned to the cell for reuse.

      Included in the list of deficiencies of the OEM Alpha Metal 500
M Ionograph was the lack of sensitivity of the instrument below 10
micrograms Sodium Chloride equivalents (10 ug NaCl eq.), the obvious
degradation of test data due to atmospheric Carbon Dioxide (CO2)
contamination, the lengthy cycle time of the instrument, the
troublesome maintenance of a 75% alcohol 25% water solution balance,
and the obvious health, hazardous waste, and fire potential
associated with the extract solution.

      The solution to the problems stated above was to modify the OEM
500 M Ionograph and to improve the specific performance of the
instrument to the needs of IBM.

      To satisfy the requirements, the first issue to be addressed
was operator safety.  A major safety issue for the OEM Ionograph was
that it required that a mixture of 75% isopropyl alcohol and 25%
water be maintained as the working fluid (extract fluid) for the
instrument.   This mixture represented a maintenance problem, a fire
hazard, and a toxic chemical danger to the operator.

      The Modified Ionograph is much safer to use than the OEM
ionograph since the Modified Ionograph uses pure water as the extract
fluid rather than the previously prescribed alcohol mixture.

Background discussion:

      Making the transition from an alcohol based extract to a pure
water extract...