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Microelectronics International

Publisher:
Emerald Group Publishing Limited
Emerald Publishing
ISSN:
1356-5362
Scimago Journal Rank:
22
journal article
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Thick Film Superconductors Preliminary Results

Hrovat, M.; Bernik, S.; Kolar, D.

1988 Microelectronics International

doi: 10.1108/eb044316

A superconducting material with the composition YBa1.8Pb0.2Cu3O7 was synthesised. The influence of PbO addition on the sintering and formation of the superconducting compound YBa2Cu3O7 was investigated. A thick film paste, prepared from prereacted material and an organic vehicle, was fired on Al2O3 and ZrO2 substrates. The resistivity of samples on ZrO2 substrates decreased to zero around 90 K, while samples on Al2O3 substrates did not reach zero resistivity until 77 K, which is probably due to the differences in thermal expansion coefficient between Al2O3 and the superconducting material. Interactions between Pt alloy based thick film conductors and superconducting material were studied.
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Photonic Systems InterconnectionsOvercoming the High Speed Electronics Bottleneck

Hartman, D.H.

1988 Microelectronics International

doi: 10.1108/eb044318

Fundamental engineering limits to very high speed electronics switching systems are employed. These limitations are caused by packaging and interconnection constraints, as well as device switching speed. From the device viewpoint, reactive parasitics caused by the packaginginterconnection scenario are discussed. From the systems level perspective, overall delay, delay variance and power consumption are explored. The important problem of clock distribution in high speed synchronous digital systems is discussed. These limitations are then revisited with photonics implementation in mind. Comparisons are made between the electrical and photonic approaches. Some engineering limits to the photonic alternative are laid out.
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Discrimination of Chemical Compounds and Functional Groups by Pattern Recognition Using an Integrated Sensor

Oishi, T.; Kaneyasu, M.; Ikegami, A.

1988 Microelectronics International

doi: 10.1108/eb044319

An integrated sensor with three elements zinc oxide, tin oxide and tungsten oxide was fabricated by thick film techniques in order to develop a smell sensor. Using this sensor and pattern recognition method, the possibility of identifying 15 chemical compounds which belong to the alcohol, ester, ketone, benzene and hydrocarbon group was examined. The following results were obtained All 15 compounds have different patterns, so they can be individually identified compounds which have the same functional groups have similar patterns and, when gas sensitivity of three elements is displayed in a threedimensional space, the compounds with the same functional group form a specific closed space. This indicates that the sensor can identify functional groups of chemical compounds.
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Fatigue Fracture of Leads of SMT Components Caused by Ultrasonic Cleaning

de Kluizenaar, E.E.

1988 Microelectronics International

doi: 10.1108/eb044320

Ultrasonic cleaning is an effective aid in the removal of flux residues from surface mounted circuits. However, an overintensive and too extended ultrasonic load of surfacemounted electronic circuits, on ceramic substrates, occasionally causes the fracture of component leads. In a metallurgical study, it was found that the fracture mechanism is fatigue. The fundamental cure for this problem is to limit the ultrasonic load to a level below the fatigue limit of the leads. This can be achieved by limiting the ultrasonic power input in the bath. Other beneficial measures are to limit the cleaning time and the ultrasonic frequency, and to prevent the components from coming into contact with other parts during cleaning.
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Present State of Directly Solderable Copper PTF

Tsunaga, M.; Kato, S.

1988 Microelectronics International

doi: 10.1108/eb044322

This paper describes a newly developed Copper PTF Polymer Thick Film which is characterised by direct solderability and high electrical conductivity. This Copper PTF claims to solve various problems existing in the conventional subtractive or firing process. It also realises new circuit production processes which are difficult to attain if conventional methods are applied.
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Accelerated Life Test of Thick Film Resistors

Golonka, L.; Kozlowski, J.; Nitsch, K.

1988 Microelectronics International

doi: 10.1108/eb044323

The rapid assessment of thick film resistor reliability is presented. This relies on the application of constant power pulses. The longterm stability of the resistors is predicted on the basis of the value of the minimal destroyed power applied during the pulse. The results are compared with the longterm behaviour of the tested samples.
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Two Thick Film Thermal Sensors

Kwikkers, T.

1988 Microelectronics International

doi: 10.1108/eb044324

For the production of sensor elements, thick film technology can be used. Advantages of this technology such as ease of production, low cost, high reliability and the possibility of integration with frontend electronic circuits, make the thick film sensor an interesting alternative to existing sensor elements. In this paper two examples of thick film thermal sensors are presented.
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Copper Ballwedge Bonding and Its Problems

Tielemans, L.

1988 Microelectronics International

doi: 10.1108/eb044325

An evaluation of the feasibility of copper ballwedge bonding on Au, Cu thick film and aluminium metallisations was carried out. This evaluation is not merely a check for feasibility, but will also give more insight into the problems concerning copper ballwedge bonding. This article does not pretend to represent profound research on copper ball bonding, but will give qualitative insight. Copper ball bonding, without using cover gas, is possible, but the bond quality decreases. Extrusion and penetration of the ball bond in the substrates are caused by the hardness of the copper. This can only be avoided when the hardness of the substrate is matched to the hardness of the copper ballwire. Bonding mechanisms are similar for bonding on thick film to those for bonding on metallisations. Matching hardness of the substrate to the ballwire seems to be a necessity for proper ballwedge bonding.
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The Surfactant FluxA New Flux for the Ozone Age

Becker, G.; Biverstedt, A.; Tolvgrd, A.

1988 Microelectronics International

doi: 10.1108/eb044326

The development of a new type of fluxthe surfactant fluxis described. This flux is applied in a very thin layer and must be totally dry before soldering. It is not necessary to clean PWBs after soldering for functional or aesthetic reasons. Even the results of the surface insulation resistance SIR test suggest no need for cleaning. The flux allows a very high soldering speed, at least double that of normal fluxes. Thus the heat input into the materials involved is minimised, with the consequence of less damage. It is not the chemicals which make the flux highly active but the concept. This new concept makes it possible to design non or low corrosive fluxes in a wide range for purposes where highly corrosive fluxes must be used today.
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Nokia Electronics, Helsinki, Finland

Turnbull, R.B.

1988 Microelectronics International

doi: 10.1108/eb044327

Scandinavia is always one of my favourite destinations for a number of reasons. First of all, I like the cleanliness of the atmosphere which certainly helps to keep one fresh at the end of a long day. Then on some days it gives that incredible clarity and luminosity so admired by artists and which in turn may have led to the clean lines of Scandinavian design. The striking memorial to Sibelius is a tribute to both Finnish design and her most famous musician. In fact, Finlandia is the first piece of classical music I can remember and 1 first heard it on earphones using a crystal set. In those days virtually all receivers were hand made, even to handwound coils. Loudspeakers were an expensive rarity.
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ISHM news

Kwikkers, T.; Lantaires, J.; Turnbull, R.B.; Law, H.T.; George, Barry; Savage, Dave

1988 Microelectronics International

doi: 10.1108/eb044328

On 20 April ISHMBenelux held its 1988 Spring meeting at the Grand Hotel Heerlen. This meeting was totally devoted to implantable devices, in particular to the technologies used for these high reliability, extremely demanding devices. For this meeting ISHMBenelux was the guest of the Kerkrade facility of Medtronic. Medtronic headquartered in Minneapolis, USA is the world's leading manufacturer of implantable electronic devices. Apart from the assembly of pacemakers and heartwires, the Kerkrade facility acts as a manufacturing technology centre for Medtronic's European facilities.
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Industry news

Turnbull, R.B.

1988 Microelectronics International

doi: 10.1108/eb044329

ITS Intertrade Scientific Ltd, the UK based manufacturer of the MCTBrowne InfraRed Reflow Soldering Systems for SMT and Hybrid applications, as part of their aggressive drive into Europe, has announced the signing of a distributor agreement with Maquinaria Suiza SA of Spain. Under the agreement, Maquinaria Suiza will be the sole supplier of the highly successful product range to Spain and Portugal.
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