Interconnects ceramic

Ceramic boards are currently widely used in high-performance electronic modules as interconnection substrates. They are processed from conventional ceramic precursors and refractory metal precursors and are subsequently fired to the final shape. This is largely an art a much better fundamental understanding of the materials and chemical processes will be required if low-cost, high-yield production is to be realized (see Chapter 5). A good example of ceramic interconnection boards are the multilayer ceramic (MLC) stractures used in large IBM computers (Figure 4.11). These boards measure up to 100 cm in area and contain up to 33 layers. They can interconnect as many as 133 chips. Their fabrication involves hundreds of complex chemical processes that must be precisely controlled. 

FIGURE 4.11 Cross-section of the IBM Multilayer Ceramic interconnection package. Various layers in this interconnection device are shown. Copyright 1982 by International Business Machines Corporation. Reprinted with permission. 

The difficulty and high cost of the fabrication of ceramic interconnect materials is their primary disadvantage and has led to recent emphasis on metallic interconnects, which will be discussed in the next section. 

Zhong Z. Stoichiometric lanthanum chromite based ceramic interconnects with low sintering temperature. Solid State Ionics 2006 177 757-764. 

Zhou X, Ma J, Deng F, Meng G, and Liu X. Preparation and properties of ceramic interconnecting materials, I.a07Ca0 Cr() n doped with GDC for IT-SOFCs. J. Power Sources 2006 162 279-285. 

Sammes NM, Ratnaraj R, and Fee MG. The effect of sintering on the mechanical properties of SOFC ceramic interconnect materials. J. Mater. Sci. 1994 29 4319-4324. 

The next two chapters discuss two supporting components of the fuel cell stack —specifically, interconnects and sealants. The interconnect conducts the electrical current between the two electrodes through the external circuit and is thus simultaneously exposed to both high oxygen partial pressure (air) and low oxygen partial pressure (fuel), which places stringent requirements on the materials stability. Ceramic interconnects have been used, but metallic interconnects offer promise... 

A completely different design has been developed by Rolls Royce. Short electrode and electrolyte stripes are applied onto a porous ceramic substrate, which functions as mechanical supporting element. The single cells are connected electrically in series using short stripes of ceramic interconnects... 

In assembling hybrid microcircuits or multichip modules, ceramic interconnect substrates fabricated using thin-film or thick-film processes are attached to the inside base of a ceramic or metal package. Generally, film adhesives that have been cut to size are used to attach large substrates (greater than 1-inch square) while either paste or film adhesives may be used for smaller substrates. Substrates may be alumina, beryllia, aluminum nitride, or silicon. 

A different tubular design is being pursued in Japan by Mitsubishi Heavy Industries (MHI). The single cells are positioned on a central porous support tube and electrically connected in series using ceramic interconnect rings. This leads to an increased voltage at the terminals of the individual tubes. The fuel is fed into the inside of the tube and air is supplied to the exterior [2, 9]. The maximum tube length is 1.5 m with an external diameter of 28 mm. With... 

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