Multilayered ceramics applications

Electronic Applications. The PGMs have a number of important and diverse appHcations in the electronics industry (30). The most widely used are palladium and mthenium. Palladium or palladium—silver thick-film pastes are used in multilayer ceramic capacitors and conductor inks for hybrid integrated circuits (qv). In multilayer ceramic capacitors, the termination electrodes are silver or a silver-rich Pd—Ag alloy. The internal electrodes use a palladium-rich Pd—Ag alloy. Palladium salts are increasingly used to plate edge connectors and lead frames of semiconductors (qv), as a cost-effective alternative to gold. In 1994, 45% of total mthenium demand was for use in mthenium oxide resistor pastes (see Electrical connectors). 

A particularly important application for aluminium electrolytic capacitors is in switch mode power supplies (SMPSs) which are now extensively used, especially in computer systems. In this application the capacitor is used essentially to smooth a rectified voltage, but it inevitably passes a ripple current I which, because of the capacitor s e.s.r., rs, leads to power losses I2rs. The switching frequency determines the size of an SMPS, and frequencies have increased from about 50 kHz to about 300 kHz over the past decade. This has led to the multilayer ceramic capacitor s challenging the aluminium electrolytic in this important application, and the signs are that it will continue to do so. 

The information about nanocrystalline ferroic powders fabricated by various chemical synthesis technologies is reported in Table 5.2. Their possible applications are also listed. Powders of the same ferroics for two different applications might be obtained by different techniques since the requirements of size distribution, morphology, agglomeration and impurity composition are determined by different technological conditions. For example, barium titanate is a dielectric with high dielectric constant and it is widely used in multilayer ceramic capacitors, whereas semiconducting properties of rare-earth doped BaTiOs are important for thermistors. 

Terashi, Y. (2000). Development of material for multilayer ceramic substrate with copper wiring in millimeter wave application, Proceedings of lEMT/IMC Symposium , pp. 382-383. Hamano, S. (3999). Glass ceramic package for mobile communication applications, Proceedings of lEMT/IMC Symposium , pp. 113-119. 

Ceramic thick films are most often used in applications where their electrical properties are exploited. In these applications, the ceramic thick films usually serve as either insulators, resistors, or capacitors. However, in many of these applications, especially those involving multilayer ceramics made from tape-cast films, the mechanical or thermal properties of the ceramic must also be considered. 

LTCC — Multilayer Ceramic for Wireless and Sensor Applications, Reinhard Kulke, Matthias Rittweger, Peter Uhlig, and Carsten Gunner, Produktion von Leiterplatten und Systemen (PLUS), Eugen G. Verlag, Seite 2131-2136, Ausgabe December 2001. 

In electronics, platinum, palladium and ruthenium are used for computer hard disks and for multilayer ceramic capacitors. Platinum and rhodium are used in sensor applications, for instance in equipment for measuring temperature. Palladium and platinum are used for dental purposes. As platinum and iridium are very resistant to chemical and high-temperature attack they are widely used for equipment in chemical industry and in laboratories. Compounds of platinum and osmium have been used in medicine for anti-cancer drugs and implanted sensors. Platinum and to some extent also palladium are used as jewelry and for investment items, such as coins and bars. 

Teijin Solufill Limited produces Solufill a high porosity PE engineering film formerly made by a joint venture with DSM whose interests were bought out by Teijin. Solufill is filled with a special ceramic powder. Solufill was formerly used in the manufacture of bulk multilayer ceramic capacitors but in 2005 Teijin decided to withdraw from this application due to weakening electronic component prices and a worsening market environment. However, Solupor, a sister product is being supplied for use as a battery separator. 

A second information is provided by the market of precious metals for electronics applications. In the United States, the largest volume in 1992 was for silver powders and flakes with 249 tons, second were silver-palladium alloys with 31 tons, followed by palladium, gold, and platinum with 6.2, 3.1, and 0.8 tons, respectively. The paste and ink formulations loaded with 60-80% of precious metals included a metal value exceeding 180 million, and the added value for the producers of powders and flakes was approximately 30-32 million. The companies making the conductive pastes added approximately 100 million to the final products. This means that in the US alone the total market was over 300 million for conductive adhesives and pastes, inferring a worldwide production worth over 1 billion dollars. The most important manufacturers of multilayer ceramic capacitors and other discrete devices using large quantities of conductive materials are located in Japan and South-East Asia. 

Several electronic applications of Sn-5Sb solder have been reported the creation of hermetic seals in multichip modules, bonding a semiconductor device onto a substrate [64], and attachment of I/O pins to multilayer ceramic substrates [65]. The braze alloy, Au-20Sn, used to attach I/O pins to ceramic chip carriers was replaced by Sn-5Sb solder. The replacement provided several... 

Recent applications of e-beam and HF-plasma SNMS have been published in the following areas aerosol particles [3.77], X-ray mirrors [3.78, 3.79], ceramics and hard coatings [3.80-3.84], glasses [3.85], interface reactions [3.86], ion implantations [3.87], molecular beam epitaxy (MBE) layers [3.88], multilayer systems [3.89], ohmic contacts [3.90], organic additives [3.91], perovskite-type and superconducting layers [3.92], steel [3.93, 3.94], surface deposition [3.95], sub-surface diffusion [3.96], sensors [3.97-3.99], soil [3.100], and thermal barrier coatings [3.101]. 

In conclusion, one should choose an appropriate multilayer system for different application purposes. For the case of fatigue wear, multilayer films consisting of two hard materials with different shear modulus, such as DLCAVC multilayer film [115], would satisfy the requirement for wear resistance. While for abrasive wear, multilayer films consisting of hard ceramic layers and soft metal layers, such as TiN/Ti and CrN/Cr [116,117] multilayer films are more competent. 

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