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Browse Prior Art Database

Circuit Feature Protection During Flash Etch

IP.com Disclosure Number: IPCOM000089019D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Ellis, TL: AUTHOR [+2]

Abstract

A standard approach for making additively plated printed-circuit boards includes the use of a very fine copper layer suitably adhered to a printed-circuit board substrate upon which a pattern for the various circuit features including printed-circuit lines is made by placing a suitable photoresist pattern on the thin copper surface. Prior to the feature definition, the thru holes and blind vias may be drilled in the printed-circuit board.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 89% of the total text.

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Circuit Feature Protection During Flash Etch

A standard approach for making additively plated printed-circuit boards includes the use of a very fine copper layer suitably adhered to a printed-circuit board substrate upon which a pattern for the various circuit features including printed-circuit lines is made by placing a suitable photoresist pattern on the thin copper surface. Prior to the feature definition, the thru holes and blind vias may be drilled in the printed-circuit board.

After the photoresist pattern is appropriately applied to and developed on the surface or surfaces of the board, copper is deposited in the patterns where the photoresist defines the lines, lands, plated thru holes, blind holes and other circuit features required on the board.

After the copper is additively plated on the defined areas of the board, a suitable metal resist is applied to the defined circuit features. The metal resist could be immersion tin, electroless nickel, plated tinlead, chromium, palladium, or gold. When this metal resist is placed on the circuit features, it covers not only the tops of the circuit features, but also is found to penetrate into the spacing between the photoresist and the sides of the circuit features, thereby providing protection to the sides of the circuit features.

Thereafter, the remaining photoresist is stripped off the printed-circuit board substrate and the base thin copper foil exterior to the circuit features is etched off using a conventio...