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Fabrication of Printed Circuits without Undercutting of Conductive Lines

IP.com Disclosure Number: IPCOM000092826D
Original Publication Date: 1967-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Lester, CG: AUTHOR [+2]

Abstract

This method permits the formation of printed conductors with accurate control of the conductor cross-sectional areas. A multilayer formation of conductors is provided which eliminates etching techniques that otherwise cause electrodes to be wider at the top than at the bottom. Conductors fabricated by this method, therefore, are able to handle more power and higher frequencies than conductors fabricated by conventional subtractive etching techniques.

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Fabrication of Printed Circuits without Undercutting of Conductive Lines

This method permits the formation of printed conductors with accurate control of the conductor cross-sectional areas. A multilayer formation of conductors is provided which eliminates etching techniques that otherwise cause electrodes to be wider at the top than at the bottom. Conductors fabricated by this method, therefore, are able to handle more power and higher frequencies than conductors fabricated by conventional subtractive etching techniques.

The method, in step 1, involves depositing a film of metal 20, typically seven microns or less, on an insulator substrate 22, typically ceramic, epoxy glass, TEFLON* or the like. A photosensitive polymer 24, for example, DYCRIL*, KPR** or Dynachem, a product of Dynachem Corp., is coated over the metal.

In steps 2 and 3, a pattern, not shown, is formed on mask 26, typically glass or photographic film by conventional techniques, and is superimposed over the polymer coated substrate. The polymer is exposed through mask 26 by a suitable light source. Undeveloped polymer 23 is removed by etching with sodium hydroxide or developers. This is followed by a deoxidizing operation. The metal foil is exposed in the areas where the polymer is removed. The remaining or developed polymer acts as a mask and a resist material to the etching solution.

The exposed conductor sections 28 are built up, as shown in step 4, by placing the substrate in a plating bath no...