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Purification and Monitoring Techniques for High Dielectric Liquids

IP.com Disclosure Number: IPCOM000087352D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 47K

Publishing Venue

IBM

Related People

Frieser, RG: AUTHOR [+2]

Abstract

By this technique, contaminants, both ionized and nonionized, are removed, and can also be monitored, by an electrode system immersed in the liquid.

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Purification and Monitoring Techniques for High Dielectric Liquids

By this technique, contaminants, both ionized and nonionized, are removed, and can also be monitored, by an electrode system immersed in the liquid.

Perfluorohexane is commonly used as a coolant for multicomponent electronic devices. Contaminants in the liquid, even in the range of parts per million, can cause device failures. The contaminants are introduced into the systems frequently as residues of the device cleaning process and solder flux. The contaminants, particularly in the presence of water, can be charged like ions or colloidal micells, or uncharged particles and molecules which in the presence of an electric field experience an induced dipole. All of these particles and molecules can be present in perfluorohexane under operating conditions. The materials in small quantities migrate. The concentration at any given time in the liquid is often beyond easy resolution of conventional analytical techniques. These contaminants moving in the coolant collect at parts of the device and after differing periods of time can accumulate and cause various types of failures, such as corrosion, shorts and interference with heat transfer.

A structure that successfully removes the contaminants is one which provides a field in the liquid. One successful design is shown in Fig. 1 in the context of a typical liquid-cooled package consisting of a device carrier substrate 10 provided with pins 12, a cover 14 provided with cooling fins 15, a suitable seal 16 between the substrate 10 and the cooling chamber, and a closure member 18 that mates with a flange 19 on cover 14. Devices 20 are shown bonded to a metallurgy pattern on substrate 10. Liquid 22, typically perfluorohexane, is enclosed within chamber 14. Immersed in liquid 22 is a cylindrically shaped electrode 24 suitably insulated from the substrate and cover. A second electrode 26 is positioned in the axis of cylindrical electrode 24. An electric field is set up between electrodes 24 and 26 by applying a suitable potential, typically 10V to 20 KV. The materials of the electrodes can be any suitable material, such as lead, tin solder and copper. When using a DC potential, both electrophoretic as well as dielectrophoretic effects are produced, which means removal of both the charged and uncharged matter. The fluids can be monitored by the simple expedient of applying a suitable potential such as 10 KV, between electrodes 24 and 26. A rise of the liquid le...