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ElectroComponent Science and Technology
Volume 11, Issue 2, Pages 97-108

Mid-Film Interconnects for Multilayer Microcircuit Packages

1Bell-Northern Research, Ottawa, Ontario, Canada
2Ontario Hydro – CNTD, 595 Bay Street, M5G 2C2, Toronto, Ont., Canada

Received 21 September 1982; Accepted 1 March 1983

Copyright © 1984 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The mid-filmR process has been developed to combine the photolithographic capability of thin film technology and the low cost, non-vacuum processing of thick film technology. In this paper, we present results on the characterization of mid-film gold for multilayer applications. The effects of various processing parameters on the properties of the conductor were investigated to establish optimum processing conditions on alumina and dielectric-coated alumina substrates. The use of a resin thickness in the range from 5 μm to 15 μm and firing temperatures from 750℃ to 1000℃ produced conductor lines with sheet resistances less than 4 mΩ/, and with adhesion strengths capable of with-standing a pull force of 2.3 Kg exerted on a 2.03 mm × 1.03 mm area. The conductor lines exhibited stable resistances upon several firings at 920℃. The ultrasonic bondability of 25 μm (1 mil) aluminum wire to the mid-film gold was observed to withstand pull forces of 7.3 ± 1.5 g before breaking the bond. In addition, it was confirmed that the resolution limit of the mid-film conductor is 50 μm for line widths and spaces. Furthermore, the prototype fabrication of a multilayer memory package has been successfully demonstrated using a combination of both mid-film and thick film processes. The finished packages were free of electrical shorts and conductor discontinuities and the resistance of the mid-film conductor lines was well within the required design specifications.