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Corrosion Indicator for Field Use Disclosure Number: IPCOM000077832D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 11K

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Chaudhari, P: AUTHOR [+2]


A corrosion indicator for field use of a computer is described.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

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Corrosion Indicator for Field Use

A corrosion indicator for field use of a computer is described.

The silver ribbon used at the present time in the field as a corrosion indicator, does not simulate the real situation in a circuit module. The free Ag zone in the module is surrounded by other alloys and compounds. The corrosion of Ag might be affected not in a simple way by these alloys and compounds. The use of an indicator is desirable. The indicator may be made by the following steps: The procedure is as follows:

1) Lay down one square cm of Ag-Pd paste on a ceramic pad. The amount of paste should be enough to give an alloy layer of 2 mils in thickness after sintering. The ceramic pad should have no drilled holes.

2) Heat the pad at 825 degrees C for 30 minutes.

3) Place a drop of molten solder (Pb-10 wt. % Sn alloy) on top of the sintered alloy. The dimension of the drop is about 0.25 cm in diameter.

4) Heat the pad at 350 degrees C for 1 minute and than at 250 degrees C for 24 hours. The heat treatment will produce free Ag around the solder.

5) When the indicator is used in the field, check dark corrosion product around the solder.