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Laser Drilled Holes in Fired Ceramics

IP.com Disclosure Number: IPCOM000076440D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Fugardi, FF: AUTHOR [+3]

Abstract

During laser drilling of a via hole 10 in a fired ceramic substrate 12 (Fig. 1), a problem exists in that ceramic slag 13 often adheres solidly to the back side via hole perimeter. In order to overcome this problem during laser drilling, comprising the normal steps of directing a gas beam 14 by a nozzle 16 through a molybdenum mask 20 to form the via holes 22 in the substrate 12, the following modification is affected. A highly conductive metal film is disposed in the regions designated 24 and 26 at the entry and exit regions of the via hole to be drilled.

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Laser Drilled Holes in Fired Ceramics

During laser drilling of a via hole 10 in a fired ceramic substrate 12 (Fig. 1), a problem exists in that ceramic slag 13 often adheres solidly to the back side via hole perimeter. In order to overcome this problem during laser drilling, comprising the normal steps of directing a gas beam 14 by a nozzle 16 through a molybdenum mask 20 to form the via holes 22 in the substrate 12, the following modification is affected. A highly conductive metal film is disposed in the regions designated 24 and 26 at the entry and exit regions of the via hole to be drilled.

The metal film imparts a stiffness to the entry edge of the hole by conducting heat therefrom at a very fast rate. Also the metal film on the exit or back side of the substrate acts as a separator between the fused slag and the under surface of the ceramic substrate 12. Furthermore, the absorbent metal coating functions as an absorbent body at the entry side of the via hole to prevent reflection of the incident laser beam 14. As illustrated in Fig. 3, the coating of a highly conductive metal film prevents the fused slag material 13 ejected from the exit perimeter of the hole from adhering to the back side of the substrate. A light scraping motion easily removes any remaining slag adhering to either the top or bottom surface of the substrate subsequent to the laser drilling operation without any damage.

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