Conductor/ceramic interface

The re arch in catalysis is still one of the driving forces for interface science. One can certainly add to the topics of interface physics the whole new field of interface problems that is about to spring out of the new high Tc superconducting ceramics, i.e. the fundamental problem of the matching of the superconducting carriers wave-functions with the normal state metal or semiconductor electron states, the super-conductor-superconductor interfaces and so on, as well as the wide open discovery field for devices and applications. 

Of the different possibilities, resonator structures were found to be well suited for materials characterization. Although dielectrics and conductors can be characterized independently, it is of key importance in a ceramic material system to characterize the conductor and dielectric together, as they will be in actual use. There can be interactions or influences at the conductor-dielectric interface that can significantly affect performance, particularly at higher frequencies. As frequencies increase, methods for materials characterization become fewer, more sensitive, and complex. All the possible methods cannot be fully treated in this chapter, and the reader is referred to the references for further information. Table 2.8a summarizes some of the test methods and considerations in their use for material characterization, whereas Table 2.8b charts the attributes of the general test methods [30],... 

With device level LTCCs, the glass/ceramic composites themselves are not used separately, but are formed with conductor wiring in each layer and via conductors between layers. Seen from a macro point of view, they can be characterized as composite materials formed of wiring metal and ceramic. For this reason, in order to improve the strength of the LTCC overall, it is effective to reduce micro and macro flaws in the metal/ceramic interface, and to predict and improve strength, with reference to the equation suggested with fiber reinforced resin material below [48],... 

Figure 9-2 The copper/ceramic interface after applying thermal shock of AT 250°C to an LTCC with copper conductor (a) and the copper/ceramic interface after conducting a bending strength test on a sample that has undergone thermal shock (b).

Electronic properties of surfaces and interfaces in semi-conductor ceramic materials... 

M., Kotzeva, V. and Kumar, R.V. (2000) Solid state ceramic sensors based on interfacing ionic conductors with semiconducting oxides. J. Eur. Ceram. Soc., 20, 2691-9. 

From a structural perspective, the degree of interface modification is responsible for regulating the kinetics of the em/measurement as a function of its influence on the structural gas permeability of electrodes, which controls the initial rate of physic-chemical reactions of adsorption-desorption and diffusion on electrodes. In addition, the sensitivity of the zirconia gas sensors is highly sensitive to chemistry and can be lost by minor changes either in the phase purity or at the presence of metallic admixtures in the ceramic ionic conductors. 

Interface Effects in Mixed Conductors, in High Temperature Electrochemistry, Ceramics and Metals, Proc. I7th Ris0 Inti. Symposium on Materials Science, ed. F. W. Poulsen, N. Bonanos, S. Linderoth, M. Mogensen, and B. Zachau-Christiansen, Ris0 National Laboratory, Denmark, Sept. 

Nevertheless, preparation of the multilayer substrate surface is more complex and is usually carried out by the users instead of manufacturers of ceramic substrates. Simply applying a polymer layer onto the as-fired ceramic surface cannot lead to successful thin-film layers. The solvent trapped in microporosities in the conductor for vias and/or at the interface between conductor and ceramics may outgas during the reflow soldering when populating components on the finished thin-film substrate, resulting in poor adhesion of thin-film metal and dielectric at the position of vias. 

Kawasaki T, Tokuhiro M., Kimizuka N., Kunitake T. Hierarchical self-assembly of chiral complementary hydrogen-bond networks in water. J. Am. Chem. Soc. 2001 123 6792-6800 Kharton V.V., Marques F.M.B. Mixed ionic-electronic conductors effects of ceramic microstructure on transport properties. Curr. Opin. Solid State Mater. Sci. 2002 6(3) 261-269 Kikkinides E.S., Stoitsas K.A., Zaspalis V.T. Correlation of structural and permeation properties in sol-gel-made nanoporous membranes. J. Colloid Interface Sci. 2003 259 322-330 Kilner J., Benson S., Lane J., Waller D. Ceramic ion conducting membranes for oxygen separation. Chem. Ind. November 1997 907-911... 

As one example, consider the interfacial phenomenon between ceramic and copper wiring. If the material or process conditions of the ceramic and copper are inappropriate, various macro and micro flaws occur. For example, in the firing process, minute pores are formed at the interface. Possible causes of the formation of the pores are (1) mismatch of the firing and shrinkage behaviors of the conductor and ceramic, (2) insufficient adherence between the conductor and ceramic in the laminating process, (3)... 

Internal interlayer delamination is where delamination occurs at the interface between the internal conductor and the ceramic, although the cracks do not reach to the outside of the substrate. The cause of the problem is an area of poor adherence between the green sheet and conductive paste in the laminated body. When there are many layers, or when the conductor on each layer is thick, there is a great difference in the thickness of the parts including the conductor and the parts with ceramic only, so that the laminated body is like a sandwich with a lot of filling (refer to Figure 7-17). Since this delamination occurs in order to release the stress within the laminated body, it takes a similar form to stepped interlayer delamination and circular delamination. 

The concept of the matching of firing shrinkage rates of ceramics and conductors was touched upon in Figure 3-1 in Chapter 3. As suggested there, when there is a mismatch in the contraction coefficient between the ceramic and metal materials, defects are formed at their interface [3,4, 5]. 

It is clear that CNTs have many advantages over other carbon materials in terms of electrical and thermal properties. These properties offer CNTs great potential for wide applications in field emission, conducting plastics, thermal conductors, energy storage, conductive adhesives, thermal interface materials, structural materials, fibers, catalyst supports, biological applications, and ceramics and so on [35]. 

To carry out electrical measurements, the component, commonly a disk sample, is provided with two electrodes. We have seen that a metal-semi-conductor interface has a specific capacitance and conductance (see section 11.4). It is therefore possible to take into account the contribution of the electrodes to the total impedance by considering a second cell Rej-C i in series with the first. We thus expect to have two semi-circles in the complex impedance plane, at least if the time corrstarUs differ by a minimum of two orders of magnitude. This is generally the case, since the electrical thickness of the metal-ceramic irrterface is much srttaller (1 rrm to 1 pm) than that of the sample (typically 1 nun). 

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