Browse Prior Art Database

Process Flow for Circuitized Substrates

IP.com Disclosure Number: IPCOM000062726D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Donson, WA: AUTHOR [+2]

Abstract

Photolithographic processes that are used in the construction of circuitized substrates commonly involve multiple resist-apply and strip resist steps. A method of producing circuitized substrates that minimizes dependence on resist-related steps is as follows. 1. Metallize substrate, for example, with successive layers of chromium, copper and chromium (Cr/Cu/Cr); 2. Screen or stencil print an etch resist, which also acts as a solder mask, on the metallized substrate; 3. Etch away the top metal layer, for example, the chromium (Cr) layer not covered by the etch resist, to l areas to be wetted by reflowed solder; 4.

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Process Flow for Circuitized Substrates

Photolithographic processes that are used in the construction of circuitized substrates commonly involve multiple resist-apply and strip resist steps. A method of producing circuitized substrates that minimizes dependence on resist-related steps is as follows. 1. Metallize substrate, for example, with successive layers of chromium, copper and chromium (Cr/Cu/Cr); 2. Screen or stencil print an etch resist, which also acts as a solder mask, on the metallized substrate; 3. Etch away the top metal layer, for example, the chromium (Cr) layer not covered by the etch resist, to l areas to be wetted by reflowed solder; 4. Screen or stencil print an etch resist, which is a solder cream (solder paste), on the areas to be wetted by reflowed solder which are typically areas of chip attach or pin pad areas such as typically provided on ceramic substrates; 5. Etch away the bottom metal layer(s), for example, the copper (Cu) and chromium (Cr), layers, to leave the desired circuitry on the substrate with connection points, such as areas of chip attach and pin pad areas, covered with the reflowable solder paste.

Disclosed anonymously.

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