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TEFZEL Removal From Flat Wire Bus Via UV Laser

IP.com Disclosure Number: IPCOM000040107D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Burns, FC: AUTHOR [+4]

Abstract

TEFZEL*, a copolymer of ethylene and tetrafluoroethylene, is used as a covering for flat wire busses. When the TEFZEL is to be removed from the wire busses, it can be taken off by burning the material with an oxygen-propane torch. An undesirable result of using a torch is that the copper surface of the flat wire busses is highly oxidized and the TEFZEL is thermally damaged in those areas adjacent to where the torch was used. The TEFZEL can be removed using a UV laser without oxidizing the underlying copper layer. The removal is accomplished in the following manner. TEFZEL on the wire busses can be removed by a UV-excimer laser operating at 248 nm or 193 nm.

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TEFZEL Removal From Flat Wire Bus Via UV Laser

TEFZEL*, a copolymer of ethylene and tetrafluoroethylene, is used as a covering for flat wire busses. When the TEFZEL is to be removed from the wire busses, it can be taken off by burning the material with an oxygen-propane torch. An undesirable result of using a torch is that the copper surface of the flat wire busses is highly oxidized and the TEFZEL is thermally damaged in those areas adjacent to where the torch was used. The TEFZEL can be removed using a UV laser without oxidizing the underlying copper layer. The removal is accomplished in the following manner. TEFZEL on the wire busses can be removed by a UV- excimer laser operating at 248 nm or 193 nm. In order to remove the TEFZEL, it is only necessary to have the laser light incident on the TEFZEL at sufficient fluence (energy/square centimeter) to cause ablative or thermal decomposition of the TEFZEL. The removal of the TEFZEL at 308 nm results in significant thermal degradation, and a black sooty deposit is left on the copper. Attempts to etch a clean channel through the TEFZEL using 308 nm light were unsuccessful. However, at 248 nm it was possible to etch a clean channel through the TEFZEL and to uncover a bright clean copper surface, with minimal thermal degradation The absorption of the TEFZEL increases at shorter wavelengths. The increase in absorption at shorter wavelengths correlates with the increase in efficiency of the etching at shorter wavelengt...