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Etching of Epoxy Glass Laminates

IP.com Disclosure Number: IPCOM000094903D
Original Publication Date: 1965-Jul-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Carbone, FJ: AUTHOR

Abstract

Top and bottom layers 11 and 12 of copper are etched to form top and bottom hole recesses 13 by standard printed circuit board techniques. Substrate 15 is comprised of epoxy resin 17 and embedded glass 19 as a fabric. Chemical removal of the substrate at the hole is done by the following process. In a two-step etching process, concentrated sulfuric acid is used at 110 degrees C. to dissolve the epoxy resin. After rinsing and air-drying the glass fibers, these are dissolved by a dilute solution of ammonium bifluoride (NH(4)F.HF) (160 grams per liter at 50 degrees C.) to give through-holes. The ammonium bifluoride is hydrolized reversibly to form hydrofluoric acid. Undercutting into the epoxy is minimized and the glass cloth is readily dissolved with such a source of HF.

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Etching of Epoxy Glass Laminates

Top and bottom layers 11 and 12 of copper are etched to form top and bottom hole recesses 13 by standard printed circuit board techniques. Substrate 15 is comprised of epoxy resin 17 and embedded glass 19 as a fabric. Chemical removal of the substrate at the hole is done by the following process. In a two- step etching process, concentrated sulfuric acid is used at 110 degrees C. to dissolve the epoxy resin. After rinsing and air-drying the glass fibers, these are dissolved by a dilute solution of ammonium bifluoride (NH(4)F.HF) (160 grams per liter at 50 degrees C.) to give through-holes. The ammonium bifluoride is hydrolized reversibly to form hydrofluoric acid. Undercutting into the epoxy is minimized and the glass cloth is readily dissolved with such a source of HF. This process can also be used when strips of copper are formed on an epoxy-glass layer mounted on a copper layer. Removal of the epoxy-glass between the copper strips down to the copper layer can be done without undercutting the resin.

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