Vacuum applications of the quartz crystal microbalance

Vacuum applications of the quartz crystal microbalance

WORLD A B S T R A C T S ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y 231 Design considerations in thick-film hybrid microcircuits la...

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WORLD A B S T R A C T S ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y

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Design considerations in thick-film hybrid microcircuits layout. M. SOBHANIand H. R. ISAAK. Solid St. Technol., June (1969), p. 37. Translation from a schematic to fabrication of a thick-film hybrid microcircuit requires a knowledge of both circuit and process design. A lack of information in proper layout procedures often results in circuits that are unnecessarily difficult to fabricate. Design guidelines are given to aid in optimization of the circuit layout. Optimum geometries are discussed with particular emphasis on resistors. Examples of circuits are given from schematic to the finished product to illustrate the design layout procedure. High-resistivity thin-film resistors for monolithic circuits--A review. R. K. WAITS,Solid St. TechnoL, June (1969), p. 64. Thin-film resistors on monolithic integrated circuits--where the resistors are deposited on the integrated circuit chip---have, until recently, been limited to sheet resistivities of 500 ohms/square or less. One important advantage of thin-film resistorslthat of space saving--cannot be realized until high sheet-resistivity (greater than 2000 ohms/square) films are available. Approaches based on metallic films, metal-oxide mixtures, and silicon-metal films are reviewed. Silicon-metal films show the most promise for high-value resistors on monolithic circuits. Resistor adjustment methods are discussed; laser-annealing or cutting may prove to be a practical method of trimming resistors during circuit operation and testing.

Thick films in automotive equipment. R. W. NOLAN, Electron. Compon. June (1969), p. 711. The year 1967 saw the introduction of microelectronics into automotive charging systems on both sides of the Atlantic. This was a highly significant step, for it meant that microelectronics could not only compete with discrete component electronic assemblies but also with the traditional methods of manufacturing electromechanical voltage regulators. The motor industry is highly cost conscious and will not pay a premium for a new component unless it offers some outstanding technical advantage. Under these latter conditions, the component would be fitted to high performance or luxury cars. The microelectronic regulator described in this paper does not fall into this class. It is intended to control a new range of alternators designed specifically for the average family car, which is the most cost conscious are in the automobile industry. Die and wire bonding capabilities of representative thlck-film conductors. J. P. BUDD,Solid St. Technol., June (1969), p. 59. The use of thick film conductive glazes for semiconductor packaging applications has grown significantly in the past few years. This trend is due to the inherent simplicity and reproducibility of the screen-and-fire technique, low capital investment and the ease with which circuit configurations can be modified simply by changing screens. T o date, little information has been available to guide the circuit manufacturer in selecting and processing thick film pastes to obtain the required die and wire bonding properties of the fired metallization. This article describes the thermocompression and ultrasonic wedge bonding capabilities of several representative, commercially available thick film conductor compositions with fine gold and aluminium wire. The ultrasonic eutectic bonding of silicon dice to a variety of gold thick-film conductors is also described. Thick-film s c r e e n priming. B. M. AUSTIN,Solid St. Technol., June (1969), p. 53. The basic screen printing process is described. The effects on print thickness of "angle of attack, characteristic of the blade, and substrate variations are described. The relationship between print quality and both blade-tosubstrate distance and the nature of the blade itself is treated. The relatively new contact printing technique is reviewed. A comparison between the use of masks is compared with that of screens. The technique of automatic screen printing is discussed.

Vacuum applications of the quartz crystal m i c r o b a l a n c e . M. A. BAKER,Vacuum 19, No. 7 (1969), p. 327. The oscillating quartz crystal microbalance is well established as a film thickness monitoring instrument. However, there are number of other interesting vacuum applications of the quartz crystal microbalance. Among those considered are the measurement of oil vapour contamination from vacuum pumps, the measurement of the condensation rates of cryopumped gases, and the measurement of the partial pressure of water vapour in vacuum drying processes. Also considered are the microbalance accuracy of weighing and sources of error applicable to these measurement.