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Detection of Failures on Printed Circuits

IP.com Disclosure Number: IPCOM000074884D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Sambucetti, CJ: AUTHOR [+2]

Abstract

A specimen 10 such as a phenolic or epoxy printed-circuit board with a gold circuit line 11 on a copper base, not shown, is placed in an aqueous solution 12 containing simply 5g% acetylcholine iodide and 1g% gelatins in container 13. Gold plated auxiliary electrode 14 is immersed in solution 12. Battery 15 is applied between line 11 and electrode 14 connecting to points 2 through switch 18, making line 11 the anode. Where there are no flaws or imperfections on the line 11 its surface is covered by a smooth dark brown film. Discontinuities and breaks revealing copper 16 present, show at this stage as pink spots 17 scattered over the line 11. The test can be suspended at this stage to discard specimen 10.

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Detection of Failures on Printed Circuits

A specimen 10 such as a phenolic or epoxy printed-circuit board with a gold circuit line 11 on a copper base, not shown, is placed in an aqueous solution 12 containing simply 5g% acetylcholine iodide and 1g% gelatins in container 13. Gold plated auxiliary electrode 14 is immersed in solution 12. Battery 15 is applied between line 11 and electrode 14 connecting to points 2 through switch 18, making line 11 the anode. Where there are no flaws or imperfections on the line 11 its surface is covered by a smooth dark brown film. Discontinuities and breaks revealing copper 16 present, show at this stage as pink spots 17 scattered over the line 11. The test can be suspended at this stage to discard specimen 10. To have a permanent record of the failure or to repair damage, a pulse of same voltage and opposite polarity is applied, by reversing switch 18 to contacts 3. On reversing the current direction, the dark brown film vanishes from the gold, leaving a black spot where the pink spot 17 formed before. Voltages and auxiliary electrodes vary depending on the surface area of the specimen when gold or copper plated circuits are covered by protective insulating films, e.g. to prevent atmospheric corrosion, etc. Ceramics, paints, or epoxy breaks in films are detected with the procedure. The process applies to noble metal coatings including platinum and palladium deposited over nonnoble metal-clad substrates (nickel, etc.) This applie...