Ashok Narayan Prabhu

Co-fired ceramic on metal multichip modules for advanced military packaging

A novel, low temperature co-fired ceramic on metal (LTCC-M) multilayer circuit board technology intended for dual-use by both the military and commercial market sectors is described in this paper. This technology has been optimized for low cost, high circuit density multichip modules and board level integration. Limitations of the present low-temperature co-fired ceramic systems have been overcome by using a metal core in the LTCC-M technology. This technology readily allows the design of rugged, yet lightweight, electronic modules. In addition, the co-fired metal core permits this technology to be readily scaleable in terms of circuit density, size, and power dissipation; thereby making this an excellent candidate for a dual-use technology. Several advanced military packaging applications are pointed out in this paper.<<ETX>>

31.2: Fabrication of 165 μm Pitched PDP Back Panel Based on LTCC‐M Technology

Orion Electric Co. has developed an XGA resolution, 165 μm pitch 25″ Plasma Display Back Panel by combining the process and cost benefits of the LTCC-M (Low Temperature Co-fired Ceramic on Metal) substrate technology with a high-resolution one-step “Barrier Embossing” technique. Tensile tests on green sheets were conducted and the effects of green sheet mechanical properties on embossed barrier height were investigated. LTCCM back panels (8″) were sealed to sodalime glass front panels and the assembled parts were successfully evacuated to 10−7 torr without cracks on the glass side.

Development of a new multilayer copper-dielectric system

The development of a copper conductor and multilayer dielectric ink system, designed to overcome the dielectric porosity, Cu diffusion, and reheat stability problems commonly experienced with thick films fired in nitrogen, is discussed. The characteristics of the Cu and dielectric inks, which are formulated for screen printing on alumina substrates and firing in nitrogen at peak temperatures of 900-925 degrees C, are discussed. The dielectric, which is based on a devitrifying glass with ceramic oxides, produces extremely dense films having thermal expansion characteristics matching the substrate with a reheat stability up to 900 degrees C. Copper thick films on the dielectric are free from blistering in multilayers, and the dielectric is quite resistant to the diffusion of liquid flux phases present during the firing step. The dielectric typically passes the conductive salt solution porosity test with less than 1 mu A/cm/sup 2/ leakage current. The influence of the organic binder-system on dielectric film density and results of dielectric porosity and accelerated aging tests on multilayer circuit boards are discussed.<<ETX>>

Low, Medium And High Circuit Density Multichip Modules

Multichip modules (MCMS) employ uncased chips mounted and interconnected on multilayer circuit boards. The interconnect is fabricated using alternate layers of conductor and dielectric thin films connected by vias through the interlayer dielectric. Depending upon the performance, assembly flexibility and cost considerations, various approches can be used for fabricating and packaging MCMs. A number of circuit board technologies and packaging schemes applicable to different MCM applications are summarized in this paper. An effort is made to classify these MCMs into low, moderabe or high circuit density types. Several examples are provided to point out the suitability of various MCM approaches to the selected applications.