Tab lead capacitor

World Abstracts on Microelectronics and Reliability reliability of interconnections and solder-joints. The design engineer can derate the electrical stresses of electronic components to the desired level provided manufacturers have correctly specified the ratings. This paper describes the experiments conducted on capacitors, resistors, toggle switches and transistors to find the correctness of the specified ratings. It was found out that the manufacturers either underestimate or overestimate their components regarding electrical ratings. A method to determine the ratings has also been given. It is emphasised that all manufacturers should follow a uniform procedure in deciding the ratings and that users should verify the validity of the specified ratings. Encapsulation, sectioning and examination of multilayer ceramic chip capacitors. G. J. EWELL and W. K. JONES. Proc. Electron. Components Conf Arlington, Va., May 16-18, 1977. p. 446. As the reliability of multilayer, ceramic capacitors becomes more critical, the destructive physical analysis (DPA) of lot samples will become mandatory. The techniques of DPA must be such that they induce no changes in the part's structure. Handling~ encapsulation, grinding, polishing and examination techniques are detailed herein. Tab lead capacitor. G. R. LOVE, E. D. McLAURIN and W. E. HUCKS. Proc. Electron. Components Conf. Arlington, Va., May 16-18, 1977. p. 458. Differential thermal expansion between a monolithic chip capacitor and the common hybrid substrate materials gives rise to significant stresses in the chip. For conventional attach techniques and conventional chips, these stresses may exceed the strength of one or more of the components, chip, termination, substrate metallization, or solder, in the assembly with disastrous effects. Further, common choices of materials aggravate the basic problem by "building-in" opportunities for delayed failure due to slow formation of brittle intermetallics in the assembly. We have examined this problem in detail, and we offer a solution that incorporates material, process, and design innovations which essentially eliminate these problems as sources of device failure. Thermally stable tantalum oxide thin film capacitors. SHIGEHIKO SATO, KATSUAKI YANAGISAWA, SUSUMU OKAMOTO and HAJIME SASAKI. Proc. Electron. Components Conf. Arlington, Va., May 16-18, 1977. p. 374. Thin film capacitors have been developed which can withstand temperatures as high as 300°C for more than one hour. This enables capacitors to be used at higher application temperatures and to be assembled by TC bonding at high substrate temperature or by solder reflow techniques. The dielectric was tantalum oxide formed by anodization of sputtered fl tantalum films. It was heat-stabilized at high temperature and then reanodized to the desired voltage for the removal of dielectric defects caused by the heattreatment. Except for the thermal stability, no significant differences in electrical characteristics were noted between the developed and conventional tantalum oxide thin film capacitors. But the former was more stable than the latter when life-tested under various conditions of voltage, temperature and humidity. The production yield of the thermally stable tantalum oxide thin film capacitors was more than 95~,0 when a tolerance of 5~o was allowed for capacitance values. Failure mechanisms in solid electrolytic capacitors. J. BRETTLE and N. F. JACKSON. Electrocomp. Sci. Technol. 3, 233 (1977). The failure mechanism of solid tantalum and alurninium capacitors have been investigated using a combination of electrical measurements and electron microscopy. The capacitor dielectric was examined before and after life testing and changes correlated with electrical measurements. M.R. 1 6 / 6

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The basic mechanism of failure of solid tantalum capacitors is found to be field crystallisation of the essentially amorphous dielectric oxide. The growth of higher conductivity crystalline oxide during operation of the capacitors causes an increase in leakage current and may result in catastrophic failure. The effect of field crystallisation can be minimised by using high purity tantalum to reduce the number of crystallisation nucleation sites. Since crystalline growth is primarily dependant on applied voltage, high voltage capacitors are much more susceptible to failure than low voltage units. There appears to be no long term failure mechanism in solid aluminium capacitors. However, a particular problem with these units is that they are difficult to make. This is because the anodic layer is chemically less stable in the case of aluminium than in the case of tantalum. The attack is initiated during the deposition of manganese oxide by pyrolysis from manganese nitrate solution and developed by the reform process. Solid aluminium capacitors often have a lower capacitance and higher initial leakage current than comparable solid tantalum units; however, the leakage current decreases on life tests and their reliability is high. Special lot acceptance tests for multilayer ceramic chip capacitors. W. N. WESSBERGand G. J. EWELL. Proc. Electron. Components Conf. Arlington, Va., May 16-18, 1977. p. 452. Detailed, rigorous tests for acceptance of lots of multilayer ceramic chip capacitors are described. Electrical tests are listed, and illustrations of part defects detectable by external examination and by internal examination through destructive physical analysis (DPA) are given. Structural integrity and electrical stability are emphasized. Influence of defects in the silicon wafer on the properties of silicon oxide films formed by reactive sputtering. D. KROPMAN, M. VINNAL and P. PUTK. Vacuum 27 (3) 125 (1977). It is well known that the properties of SiO 2 films, formed by reactive sputtering in oxygen, sensitively depend upon the details of chemical pretreatment of the Si surface and on the conditions of oxide formation. The influence of bulk defects in the silicon wafer has, however, not been adequately studied. Bombardment of the silicon surface with electrons and ions during the initial stages of the oxide formation is accompanied by extensive interaction with the surface defects, leading to changes in the charge of these defects and properties of the deposited film in general. If vacancies are the dominant defects, then a positive charge is created in the oxide film. If both vacancies and stacking faults are present, then both positive and negative charge can appear in the SiO2 film. Which non-sinusoidal voltage may shorten the life of a capacitor? MOtSEY LERNER. Proc. Electron. Components Conf. Arlington, Va., May 16-18, 1977. p. 468. Heat dissipation in a capacitor, caused by a non-sinusoidal voltage of an arbitrary wavcform, is discussed. It is shown how to estimate the maximum and the minimum of possible losses in a capacitor when its frequency response is unknown. The width of the band of possible losses is chosen to indicate the degree of danger of overheating of a particular cpacitor by a particular non-sinusoidal voltage. Examples of a saw-tooth voltage and of a trapezoidal voltage are investigated.

Effect of oxidation on the breakdown characteristics of ahminium diffused junctions. B. JAYANTBALIGA.Solid-St. Electron. 20, 555 (1977). High voltage power rectifiers and thyristors are usually fabricated with deep diffused junctions using aluminum or gallium as the p-type dopant. Aluminum and Gallium have a relatively large diffusion coeffi-