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Process for Removing Laser-Charred Polyimide From Copper

IP.com Disclosure Number: IPCOM000042675D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

DePew, J: AUTHOR [+3]

Abstract

In the process of fabricating flexible cables for attachment to film devices, a window through the polyimide material on the thermo-compression bonding side of the cable is required. Attempts at removing the polyimide window area to expose the copper lands by laser machining techniques has been successful. However, laser machining leaves a large amount of charred polymer on the copper lands after processing. Flimsiness of the unsupported copper lands and strict dimensional tolerances limit the techniques available to clean the charred copper for subsequent precious metal electroplating. A process is described which chemically removes the charred, polymeric material and renders the copper lands receptive to adherent metal coverage by standard electroplating techniques.

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Process for Removing Laser-Charred Polyimide From Copper

In the process of fabricating flexible cables for attachment to film devices, a window through the polyimide material on the thermo-compression bonding side of the cable is required. Attempts at removing the polyimide window area to expose the copper lands by laser machining techniques has been successful. However, laser machining leaves a large amount of charred polymer on the copper lands after processing. Flimsiness of the unsupported copper lands and strict dimensional tolerances limit the techniques available to clean the charred copper for subsequent precious metal electroplating. A process is described which chemically removes the charred, polymeric material and renders the copper lands receptive to adherent metal coverage by standard electroplating techniques. The process steps, including distilled water rinses between all steps, are: 1. Anodic cleaning in alkaline cleaner at high current density. 2. HCl soak at room temperature. 3. In a room temperature mixture of ammonium persulfate and H2SO4, dip parts. 4. H2SO4 dip at room temperature. The above process steps must be repeated to remove all debris. The part is kept wet and electroplated, as required.

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