Method of Connecting Layers of Circuitry Separated by a Dielectric
Original Publication Date: 1980-Mar-01
Included in the Prior Art Database: 2005-Feb-13
An improved and simplified method of making interlevel connections on a multilayer metallized ceramic substrate, such as, an MCP (metallized ceramic polyimide) substrate, is as follows: 1. Form the first circuit layer M1 (chrome-copper-chrome) on the ceramic substrate. 2. Completely cover M1 with polyimide. Dry and thermally cure the polyimide stepwise to final cure (C-cure). 3. Form the second circuit personality M2 (chrome-copper-chrome) with the bridge structure at all of the points where connections to M1 will be required. The width of the bridge is about 1 mil and spans a distance of about 3 mils, becoming wider on either side, if desired (Fig. 1). The bridge is made part of the M2 photomask. 4.