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Plasma Smear Removal in a High Aspect Drilled Hole

IP.com Disclosure Number: IPCOM000040888D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bui, VQ: AUTHOR [+3]

Abstract

The drilling of through holes in multilayer printed circuit boards results in the smearing of epoxy layers across the copper planes. This smear must be removed and is typically accomplished by a plasma etch process. However, in the case of a high aspect ratio hole the center etches at a much slower rate than the shallow parts of the hole. This uneven etching is remedied in a procedure that yields uniform etching and smear removal throughout a high aspect ratio hole.

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Plasma Smear Removal in a High Aspect Drilled Hole

The drilling of through holes in multilayer printed circuit boards results in the smearing of epoxy layers across the copper planes. This smear must be removed and is typically accomplished by a plasma etch process. However, in the case of a high aspect ratio hole the center etches at a much slower rate than the shallow parts of the hole. This uneven etching is remedied in a procedure that yields uniform etching and smear removal throughout a high aspect ratio hole.

Using process parameters for plasma drill smear removal of 60% CF4 - 40% O2 gas composition, 3.5 kilowatts power, 1.2 liter/minute gas flow in a parallel plate reactor at pressures of less than 200 millitorr result in uniform plasma etching of the entire through hole.

Disclosed anonymously

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