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Corrosion Indicating Bridge

IP.com Disclosure Number: IPCOM000085637D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Allen, RC: AUTHOR

Abstract

In the past, the primary technique for measuring the effect of the environment on copper circuitry has been to use a standard copper coupon. Such coupons are placed in the environment which is to be measured for a predetermined period of time, and the change in weight of the coupon indicates the amount of corrosion experienced by the coupon. This can be translated into an indication of the hostility of the environment with respect to copper (or any other metal from which the corrosion indicating Bridge is made).

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Corrosion Indicating Bridge

In the past, the primary technique for measuring the effect of the environment on copper circuitry has been to use a standard copper coupon. Such coupons are placed in the environment which is to be measured for a predetermined period of time, and the change in weight of the coupon indicates the amount of corrosion experienced by the coupon. This can be translated into an indication of the hostility of the environment with respect to copper (or any other metal from which the corrosion indicating Bridge is made).

A more satisfactory technique of measuring the environment is to take a printed-circuit board which has four sets of circuit lines thereon. These four sets of circuit lines are, in effect, four resistors. Two of the sets of circuit lines are coated with a protective coating to prevent gases in the environment from attacking the copper circuit lines. The two other sets of circuit lines are uncoated, whereby the hostile elements in the environment can attack the copper. The corrosion of the copper due to the hostile environment effects the resistivity of the exposed copper lines.

The four circuit elements are connected in a standard measuring bridge circuit. This allows changes in the resistivity of the two uncoated sets of copper lines to be determined. This change in resistivity indicates the hostility of the environment towards copper.

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