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Optical Fiber Module for Efficient Laser Etching of Vias

IP.com Disclosure Number: IPCOM000038462D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Arjavalingam, G: AUTHOR

Abstract

An optical fiber module contains conical optical fibers which concentrate a laser beam to provide an efficient projection system for laser etching of vias in chip packaging materials. Coating the outside of the fibers further reduces the losses due to evanescent modes. Holes (vias) in materials are etched by the focused laser illumination. It facilitates the efficient transfer of the energy in a laser beam to prescribed points in the material where the holes are to be etched. Intense excimer laser radiation can be used to etch polymeric materials in vacuum or air, or metals in a suitable atmosphere containing a halogen gas. It is sometimes necessary to etch small holes (vias) in these materials, either isolated or in non-uniform arrays.

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Optical Fiber Module for Efficient Laser Etching of Vias

An optical fiber module contains conical optical fibers which concentrate a laser beam to provide an efficient projection system for laser etching of vias in chip packaging materials. Coating the outside of the fibers further reduces the losses due to evanescent modes. Holes (vias) in materials are etched by the focused laser illumination. It facilitates the efficient transfer of the energy in a laser beam to prescribed points in the material where the holes are to be etched. Intense excimer laser radiation can be used to etch polymeric materials in vacuum or air, or metals in a suitable atmosphere containing a halogen gas. It is sometimes necessary to etch small holes (vias) in these materials, either isolated or in non- uniform arrays. Presently, the use of masks for projection etching or contact etching of these vias is envisaged. A problem of conventional projection and contact etching is the inefficient use of the laser beam, since most of the beam is blocked by the mask used. This method uses a specially designed optical fiber module M to etch vias which results in the efficient transfer of the radiation in the laser beam to the points where the vias are required. The schematic of the module is shown in Fig. 1. Conical optical fibers F are held together in a frame. The core diameter of the fiber at the output end O is appropriately chosen to produce the vias required. The output O ends, shown in Fig....