Microelectronics International

Wall, John; Sinnadurai, Nihal

1998 Microelectronics International

doi: 10.1108/13565369810233096

This paper identifies component industry trends, examines the traditional methods of achieving space quality, addresses how the space industry can adapt to this changing scenario, looks at the options for space standardisationqualification, challenges some established practices and, finally, considers performance specifications.

Jacobson, David M.; Sangha, Satti P.S.

1998 Microelectronics International

doi: 10.1108/13565369810233104

The set of properties required for microwave packaging materials intended for aerospace applications is discussed in relation to the current range of materials that are commercially available. Initiatives are being taken to replace kovar, the established packaging material, with substitutes which are lighter, stiffer and offer superior heatsinking. Promising in this regard are new family of berylliumberyllia and also siliconaluminium SiAl alloys high in silicon, with ratios of constituents chosen such that they optimally complement gallium arsenide MMIC devices and alumina circuit boards. Both types of material are relatively easy to machine and electroplate. Demonstrator microwave amplifier modules incorporating the SiAl alloys have been designed for space applications and have been successfully produced and tested. The manufacturing technology that has been developed for this purpose is described.

Harsnyi, Gbor; Liu, Yanqing; Kinzy Jones, W.

1998 Microelectronics International

doi: 10.1108/13565369810233113

Specially formulated frit materials have been applied in thick film superconductors similar to the standard thick film materials in order to achieve processing parameters closely compatible with conventional thick film technology and alumina substrates. The applied frits have improved the adhesion and superconductor properties at the same time due to a superconductor bridge formation between the grains. Both YBCO and BSCCO systems have been analyzed. The results are promising.

Belavi, Darko; oba, Stojan; Pavlin, Marko; Roak, Dubravka; Hrovat, Marko

1998 Microelectronics International

doi: 10.1108/13565369810233122

Silicon piezoresistive pressure sensor dies are mounted on a ceramic substrate where the signal conditioning electronics are implemented in thick film technology. In this paper some of these techniques, e.g. special attachment and bonding requirements, methods for temperature compensation, the principles of parameter adjustment, and encapsulation, are presented. For illustration two examples are described. The first is a multipoint monitoring system with 720 measuring points in a test mattress. The second example is a family of industrial pressure transducers.

Philippov, Ph.; Arnaudov, R.; Yordanov, N.; Ianev, V.; Gospodinova, M.

1998 Microelectronics International

doi: 10.1108/13565369810233131

Investigations of material parameters within the system Al, Al2O3, Ta, Ta2O5 and TaOxN1x are presented. This combination is characteristic when using Al sheet for production of substrates including electronic interconnections, vias and resistive groups. They can serve for MCMs due to the specific features of Al. The technological process includes first electrochemical oxidation of Alsheet as base isolation layer Al2O3 5070m. This process is followed by vacuum deposition of relatively thick layers of Al 25m. Each layer is then processed by lithographic methods followed by selective electrochemical oxidation as a help process for structuring. The development of this combined structuring method allows the simultaneous achievement of interconnections Al and isolation Al2O3 levels with least size up to 50m. The importance of the method consists of a vertical combination of several conductive layers of Al structured as described above, burying the interconnections in the insulating Al2O3 films. All necessary combinations and configurations of different kinds of microstrip lines are possible. The dielectric characteristics of Al2O3, achieved through the above mentioned method, can be changed in accordance with the parameters of the technological steps and filling of the porous structure. Thus some interesting high frequency features of microstrips are obtained. Extra advantage is the ability of combination of conductive Al layers with other types of such layers as tantalum Ta. With Ta can be achieved other permittivity constants of the insulation layers and in combination with TaOxN1x intermediate planes of resistive groups are developed. The measurement of the stripline parameters is done by microwave technics, because the desired application of the substrates is for highspeed digital signals in the GHz range.

Philippov, Ph.; Arnaudov, R.; Yordanov, N.; Gospodinova, M.

1998 Microelectronics International

doi: 10.1108/13565369810233140

In this paper we present recent studies on the electrochemical migration processes in Ag thin film parallel microstrip lines in MCMD structures. The basic concept is applying accelerated local droptest of water solutions onto the surface of two adjacent lines, under a given voltage potential. These operational conditions are often met in the interconnection line buses, placed in the top assembly level of multilayered hybrid structures. The subject of investigations are MCMD developed on Alsheet carrier with internal conducting and isolating layers, produced through unique selective electrochemical anodization of Al and Ta. This technology process also enables the creation of embedded R and C passive components on the base of TaOxN1x and Ta2O5 or Al2O3 respectively. We propose an electrochemical deposition of AgSb alloys on the surface of Al interconnection lines and contact pads to ease the bondability and solderability in chip mounting procedures. The artificially created silver migrated defects and partial shorts are investigated through the high frequency method of coupled transmission lines in order to eliminate the errors and insufficient validity of DC direct measurements.

Moran, Peter

1998 Microelectronics International

doi: 10.1108/13565369810234978

In order for system designers to make full use of the successive generations of semiconductor devices it is becoming increasingly necessary to choose interconnection systems that are tailored to the application. As this trend becomes more pronounced, the limitations of traditional methods of constructing boards onto which electronic components can be assembled are becoming more obvious. In this paper the application of selective electroplating, a technique that has been in use for many years but has not previously been fully exploited, is discussed. It is shown by examining a number of case studies that with a small amount of innovation this basic technique can be extended to meet the needs of a number of application areas while still operating within the normal processing windows of the materials.