Browse Prior Art Database

SUBSTRATE FOR ELECTRONIC COMPONENTS

IP.com Disclosure Number: IPCOM000005977D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2001-Nov-21
Document File: 2 page(s) / 79K

Publishing Venue

Motorola

Related People

Xavier Sheehy: AUTHOR [+4]

Abstract

A polyimide and aluminum substrate is described that is preferably fabricated using standard integrated circuit photolithography liftoff methods rather than etching techniques. A prior substrate construction contains alternating layers of copper (conductor) and polyimide (dielectric) separated and attached using continuous sheets of adhesive. Vias and through holes are made by etching or drilling the copper/polyimide composite, and electroplating copper to complete the interconnect. The resultant packet of layers of copperlpolyimide is then glued to an aluminum heatsink. This prior construction is a tradeoff of thermal performance, circuit/interconnect density, manufacturability and cost.

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MOTOROLA Technical Developments Volume 11 October 1990

SUBSTRATE FOR ELECTRONIC COMPONENTS

by Xavier Sheehy, Ted Grzeskowiak, Larry Osburn and Mark Fulcher

   A polyimide and aluminum substrate is described that is preferably fabricated using standard integrated circuit photolithography liftoff methods rather than etching techniques. A prior substrate construction contains alternating layers of copper (conductor) and polyimide (dielectric) separated and attached using continuous sheets of adhesive. Vias and through holes are made by etching or drilling the copper/polyimide composite, and electroplating copper to complete the interconnect. The resultant packet of layers of copperlpolyimide is then glued to an aluminum heatsink. This prior construction is a tradeoff of thermal performance, circuit/interconnect density, manufacturability and cost.

   The proposed substrate construction begins with an aluminum heatsink 16, with a top layer coat of polyimide 12 which is applied in liquid form and then cured. A layer of aluminum (conductor) is sputtered onto the layer 12 and prc- vides a first layer of electrical interconnect. Conductor paths 13 are preferably defined by photolithography liftoff tech- niques which provide for removal of undesired aluminum areas, and then a second coat of polyimide is applied and cured. Vias 14 and 15 are etched into the polyimide using a similar lithographic removal process and a next layer of aluminum is sputtered. Aluminum pads 10 are...