The possibility of partial or complete replacement of PbO in fusible glass solders by less toxic components is investigated. It is found that it is impossible to find a full-fledged replacement for glasses in the lead-borate eutectic, used as the glass base in glass soldering compositions for sealing glass ceramic packages of integrated microcircuits at temperatures 390 -420°C, within the systems PbO -P 2 O 5 -ZnO -B 2 O 3 , V 2 O 5 -P 2 O 5 -ZnO -B 2 O 3 , and TeO 2 -PbO -V 2 O 5 -Bi 2 O 3 with different additives and total mass content of class-I hazard components not exceeding 70%.Integrated microcircuits are ordinarily assembled in metal, plastic, cermet, or glass ceramic packages. The latter have a number of advantages: manufacturability and low cost as compared with cermet packages and mechanical and dielectric properties as compared with plastics and, in part, metal packages. In addition, microcircuits assembled in cermet packages are hermetic, reliable, and long-lasting.The technical-operational characteristics of the cermet packages of integrated microcircuits are largely determined by the properties of the glass solders used to glue the ceramic parts and the metal leads of the microcircuits in a hermetic case. In this connection the glass solder must form a mechanically strong and chemically stable vacuum-tight dielectric layer between the parts of the package and the leads of the microcircuits at a prescribed temperature.The main characteristics of the glass solders are the volume resistivity r, permittivity e, CLTE, and sealing temperature. The higher r and the lower e of the glass solder, the more the leads can be placed per unit surface area of a package and therefore the size and mass of a device can be decreased to the maximum extent possible for its prescribed functional possibilities. Modern electronic devices often operate with sharp temperature differentials, so that the microcircuits must possess a high heat resistance. This condition can be satisfied if the CLTE of the glass solder, the ceramic base of the package, and metal leads of the microcircuits are all compatible with one another. Microcircuit indicators such as the maximum working temperature and the operational stability and service life are temperature dependent, and these dependences are largely contradictory. Thus, to increase the working temperature it is best to use refractory glass solders, but high sealing temperatures are a source of thermionic emission of electrons, which greatly decreases reliability, stability and service life of microcircuits. In this connection a sealing temperature of 390 -420°C is considered to be optimal.The most suitable glass bases meeting the indicated requirements are obtained with a lead-borate eutectic (85% 3 PbO, 15% B 2 O 3 ) base [1 -3]. The deformation onset temperature of the glasses synthesized in this system are t d.o = 305 -350°C, CLTE -(100 -115)´10 -7 K -1 , surface crystallization near the sealing temperature (400 -450°C) -1 -15%, r at 150°C -to 10 11 W × cm and e -18 -19. With cryst...

No abstract

An influence of p-eucryptite glassceramics on the sintering ability, sintering mechanisms, and structure of alumina ceramics has been researched by methods of DTA, TG, DTG, XRD, dilatometry, optical and electronic microscopy. The thermal incompatibility between A l l 0 3 and p-eucryptite glassceramics that results fiom the difference between their thermal coefficients of expansion (TEC) has been overcome by use of superfine powders and thorough blending of the base mixture. A phase composition, microstructure, TEC, mechanical and electrical properties, and thermal-shock resistance of alumina ceramics containing p-eucryptite glassceramics have been determined.A possibility of replacing P-eucryptite glassceramics by the equivalent amount of Li~0.2Si02 containing glass or a mixture of Li2CO3 u SiOl powders has been demonstrated.

Experimentally substantiated recommendations on selecting compositions and technologies for synthesis of glass solders with assigned properties within the soldering temperature limits of 390 -450°C and CLTE of (60 -70)´10 -7 K -1 , designed for hermetically sealing the ceramic packages of integrated microcircuits are reported.In many areas of science and technology, glasses, sitals, ceramic, and different composite materials are used as construction materials in addition to metals and alloys. Glasssolder materials -transition glass, glass cements, sitals, and glass solder compositions -are used for airtight joining of various materials. These materials are also used for interlayer insulation of integrated circuits, hermetic sealing of ceramic packages of microcircuits, preparation of pressure-seal feedthroughs in vacuum devices, dielectric resistive and conductor pastes for different applications, dielectric protective and decorative coatings on metals, alloys, etc.Transition glasses, glass cements, and sitals are close to connectable materials in properties and composition. Glass solder compositions in most cases consist of a noncrystallizable glass base and crystalline fillers. For this reason, their properties can be varied within wide limits as a function of the properties and concentrations of the constituent components. This makes it possible to standardize the approaches in designing and synthesizing glass-solder compositions with previously assigned properties.Despite the many glass-solder materials [1], there are no recommendations on selecting the compositions and technologies for synthesizing glass solders for concrete applications. For this reason, both the constituent components and the technologies for synthesizing such materials must be developed anew each time. This is a complicated task that requires a great deal of time and labor by highly trained specialists.We report experimentally substantiated recommendations on selecting the constituent components and synthesis technologies, obtained as a result of an analysis of the literature and our own studies in this area to facilitate the design and synthesis of maximally fusible glass-solder compositions designed for sealing the ceramic (Al 2 O 3 ) packages of integrated microcircuits.Many, sometimes contradictory, requirements are imposed on glass solders. The basic ones are: high wettability of the materials soldered, thermal and chemical compatibility with them, the required soldering temperature, certain mechanical, thermal, chemical, electrical, manufacturing, and performance properties.Fusible glass-solder compositions designed for sealing integrated microcircuits in particular must have: maximum low fusibility necessary for avoiding thermal immersion of the structural elements of the microcircuits, which would decrease the reliability of their work; high electric resistance and low dielectric constant, necessary for the reliable operation of microcircuits in minimal sizes;absence of or in the extreme case, low background radioactive radiation ...

Poster Sessions mode analysis of any ferroic structure. As input only the ferroic distorted structure and the (real or virtual) non-distorted one of higher symmetry is required. With this information the program AMPLIMODES identifies the displacive distortion present in the structure and decomposes it in terms of modes of different symmetries associated with irreducible representations of the highsymmetry space group. The decomposition of the structure in collective symmetry-adapted distortion modes is given in terms of global amplitudes and normalized polarization vectors for each of the modes present. The importance and character of each of the allowed symmetry modes can be extracted from a comparison of their amplitudes and the internal structure of their polarization vectors. The polarization vector of each frozen mode is presented in a crystallographic way, as a list of relative atomic displacements within an asymmetric unit. This allows a straightforward construction of virtual structures corresponding to the sole presence with arbitrary amplitudes of any of the relevant modes. This type of analysis allows to distinguish and isolate the correlated atomic displacements that correspond to the structural instabilities at the origin of the ferroic distortion, i.e. the so-called primary modes. In this way, secondary weaker induced distortions of marginal relevance are separated. The Bilbao Crystallographic Server, where this tool can be used on-line, is a free web site with many other crystallographic databases and programs [1,2]. [1] M. I.