Microelectronics International

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

1989 Microelectronics International

doi: 10.1108/eb044364

A superconducting material with a composition Y1xBa2Cu3O732x x2 Bi2O3 x 01 and 02 was synthesised. The influence of Bi2O3 additions on sintering was studied. Preliminary investigations of the BiSrCaCuO system were also made. Thick film pastes, prepared from Y1xBixBa2Cu3O7 compositions, from the compound YBa2Cu3O7 with 10 wo addition of Bi2CuO4 and from two compositions in the BiSrCaCu0 system, were fired on Al2O3 and ZrO2 substrates. All thick film materials based on YBa2Cu3O7 compound were superconducting at temperatures above 77 K when fired on ZrO2 substrates, while only a material with the starting composition Y08Ba2Cu3O6.7 01 Bi2O3 reached zero resistivity above 77 K on Al2O3 substrates. Tc onset of samples based on the YBa2Cu3O7 compound was around 95 K, and of samples from the BiSrCaCuO system between 95 and 100 K.

Messner, G.

1989 Microelectronics International

doi: 10.1108/eb044365

When designing electronic systems it is very useful to analyse the relationship between the interconnection capacity of selected packaging methods and their prices. Such an analysis is provided for the entire gamut of the interconnection spectrum from onesided PCBs to complex ICs, by a plot of the log of substrate pricesq. inch versus the log of substrate density expressed in inches of conductorssq. inch of substrate. The use of such a graphic method of analysis can produce interesting and useful insights into the potentials and tradeoffs between various current and future IC packaging approaches. After a short description and analysis of that loglog plot, this paper will apply this methodology to the derivation of the general cost relation of IC interconnections on the next level of substrates. It specifically will attempt to establish a general price relationship between packaging approaches using bare uncased chips and the chips packaged in individual packages. As a result, the costeffectiveness of the use of Multichip Module technology in the regions of very high interconnection densities will be derived and its competitiveness against other interconnection methods will be analysed.

Gustafsson, K.; Andersson, U.; Ek, S.; Liljestrand, L.G.

1989 Microelectronics International

doi: 10.1108/eb044366

The choice of high pin count ASIC packages has a major impact on the total cost and performance of the whole packaging system. Six different types of ASIC packages have been compared with respect to production aspects, availability, reliability, thermal and electrical properties and cost. Recommendations for the proper choice of packages for different types of applications are given. All packages have been directly assembled to PWBs in order to study problems with handling, solder process, testing and repairability. Some of the assembled packages have been temperature cycled in order to test the solder joint reliability. The pin grid array packages are the most frequently used high pin count packages today. However, they are expensive and throughhole mounting reduces the routing capability of the board. Pad area array packages are a hermetic alternative with a lower price for the package as well as very good thermal and electrical properties, but they need to be mounted on expensive PWBs. Another surface mountable package which is hermetic is the ceramic leaded chip carrier with fine lead pitch. This package is even more expensive than the pin grid array package and is difficult to handle. In the future, nonhermetic alternatives will probably predominate. Plastic quad flat pack and TapePak can be used below 160180 leads, while direct assembled TAB would be the best alternative for very high pin counts. Before one can use nonhermetic packages in telecom products, a large qualification programme must be performed to evaluate the longterm reliability.

Choi, J.S.; Bhalodia, M.; Samph, S.; Snowden, P.; Yahner, P.; Scoles, K.J.

1989 Microelectronics International

doi: 10.1108/eb044367

Thick film superconductors have been produced by screen printing and annealing pastes made from oxide powders and preannealed powders. These films have been analysed by Xray diffraction, microwave absorption, resistance vs. temperature measurements, and adhesion tests. Results show the correlation between structural and electrical properties.

Miyashiro, F.

1989 Microelectronics International

doi: 10.1108/eb044368

Superconductive ceramics, at present, have not yet grown into a practical material for actual application to devices and systems, but are still in the raw material stage within the research laboratory. This paper will discuss some application possibilities in Japan to the HMT field LSI wiring, transistors, hybrid ICs, and packaging, from electrical, physical and chemical aspects, supposing that only such superconductive ceramics as YBaCuOYBCO and BiSrCaCuOBSCCO under liquid nitrogen cooling can be used.

Gee, R.; Coleman, M.V.

1989 Microelectronics International

doi: 10.1108/eb044369

The environmental reliability of Series Q, a system of materials designed for advanced HIC circuits, has been studied using three different migrationresistance tests. LMRT a test which is used to assess the resistance to electrochemical migration of horizontally adjacent, closely spaced conductor tracks in a hightemperature, highhumidity environment with a voltage bias present 60C, 90RH, 48 VDC. HHBT a test which monitors the ability of a dielectric to resist electrochemical migration when vertically adjacent crossover conductor tracks are oppositely biased 85C, 85RH, 5 VDC. HBT a test which measures how well a dielectric can sustain its resistance to voltage breakdown over extended periods of time during continuous exposure to conditions of high temperature and voltage 150C, 200 VDC. The results show that the QSil and QPIus systems, the two materials systems that comprise Series Q, demonstrate excellent performance in all three areas. Predictions of how well circuits made from these materials will survive in their operating ambient over the long term, e.g., twenty years, have been made.

Lesho, J.C.; Romenesko, B.M.; Hogrefe, A.F.

1989 Microelectronics International

doi: 10.1108/eb044370

JHUAPL has developed and tested ingestible pills that telemeter core body temperature. The hybrids were manufactured as chip and wire on thick film ceramic substrates and surface mount on polyimide boards. The devices have potential applications for divers, astronauts, soldiers in combat, people working in hazardous conditions and people with hypothermia and hyperthermia. Descriptions of both circuit operation and packaging techniques are included.

Danielsson, H.

1989 Microelectronics International

doi: 10.1108/eb044371

Automotive electronics, after 1995, will be similar to aerospace electronics because there is a demand for low weight and volume together with very high speed and ultrahigh reliability. What is different is that automotive electronics must achieve all those properties at very low cost. It will be shown that when using ASIC chips the chip area is determined by the number of pins instead of the number of components of the active circuit. As ASIC technology proceeds towards line widths in the submicrometre range, the ratio of active Si area to total chip area is becoming much less than 1. This means that on the ASIC chip there is Si area which is empty. This empty Si area can be used for designing selftest circuits and redundant functions on the ASIC chip at a cost penalty slightly higher than the design cost. It will also be shown that these ASICs can work in the order of 100 MHz at the chip level. Such ASIC chips will therefore have a very high reliability at the chip level due to the inherent properties of the Si and the builtin redundancy. At the same time they can work at very high speed. From a performance point of view the best solution should be a highly miniaturised packaging technology. With selftest circuits on the chip, there is a good correlation between wafer test and final test. Therefore, from an economical point of view, working with chips will then have an economical advantage compared with working with packaged circuits. From a reliability point of view it will be shown that the solder joints are the limiting factor. A critical review is presented of the reliability problems plaguing the SMD and soldering technology of today. It will be shown that, if SMD technology is to meet the reliability demands in a future automotive environment, it will have to have solder joint failure rates better than 30 ppm over the life, 17 years, in automotive applications. The conclusion is that a multiASIC chip approach has the best potential as the solution for the future, post 1995, automotive electronics, provided there is a highly reliable chip interconnection technology available at that time.

Whatley, T.

1989 Microelectronics International

doi: 10.1108/eb044372

This paper presents the results of an investigation into alternative substrate materials to alumina and the associated techniques necessary to utilise them in microwave integrated circuits MICs. The major driving force for this work was to reduce MIC processing costs without significantly degrading the RF performance. Different glass ceramic systems were assessed and 618 GHz gain modules were produced on the most promising of these materials. One glass ceramic material, CMA6, with a dielectric content of 6 4, showed a comparable measured gain to that obtained for alumina circuits between 6 and 15 GHz. Cost analysis indicated that, with the reductions in material costs and yield improvements on using glass ceramic substrates, a cost saving of approximately 12 per module is feasible.

Kunioka, A.

1989 Microelectronics International

doi: 10.1108/eb044373

The status and the problems of HMT hybrid microelectronics technology in Japan are reviewed, and a market survey for Japan is presented.

Burdett, P.A.; Lodge, K.J.; Pedder, D.J.

1989 Microelectronics International

doi: 10.1108/eb044374

After a brief introduction to the advantages and method of construction of flip chip solder bond devices, this paper looks at different techniques that can be used to inspect these devices at various stages in their construction. These techniques include optical, infrared, acoustic and electron microscopy, radiograph, electrical and tensile testing. The advantages and limitations of each of the techniques are discussed and an outline inspection schedule is suggested.

De Mey, G.; De Vrieze, L.

1989 Microelectronics International

doi: 10.1108/eb044375

The possibilities of liquid cooling in electronics is briefly discussed. A particular application of hybrid circuit cooling is presented. Emphasis is placed on the fact that the liquid circulates under natural convection in a hermetically closed package. The module can then be used in various circumstances.

1989 Microelectronics International

doi: 10.1108/eb044376

Drive east from Frankfurt, upstream along the valley of the River Main, and in 25 kilometres or so you will reach Hanau, where once the brothers Grimm lived and collected the folklore which we now know as the famous Tales. Here too, in 1856, Wilhelm Carl Heraeus, a chemist and pharmacist, proprietor of the pharmacy which had carried the family name for many generations, succeeded in producing temperatures approaching 2000C from an oxyhydrogen flame, temperatures sufficiently high to achieve the melting point of platinum and to allow him to melt substantial quantities of this metal for the first time. Hanau was then a centre for the jewellery manufacturing industry and remains so today so the smelting of platinum and other precious metals had an immediate commercial relevance.

1989 Microelectronics International

doi: 10.1108/eb044377

EMCA has been supplying thick film materials since the mid '60s and their name will be familiar to the great majority, if not all, engaged in the manufacture of hybrid circuits. However, I for one was not so well acquainted with their background and so I welcomed the opportunity to visit their new facilities at Linton near Cambridge. For once, the M25 was reasonably clear and after an easy journey I took advantage of the fine weather to revisit the pleasant colleges and the backs by the river Cam. There is much activity in cleaning the stonework in many of the buildings the resultant appearance is splendid, especially when seen on a sunny day against a blue sky. It was a bonus to have an hotel nearby with a room overlooking the river. The next morning EMCA was just a few minutes' drive away.

1989 Microelectronics International

doi: 10.1108/eb044378

The ISHM CANAM Chapter recently organised a halfday programme of paper presentations followed by a tour of a local hybrid facility. The event took place on 26 April at the Holiday Inn, Montreal Pointe Claire, Quebec, with the theme of the papers concentrating on advances in hybrid manufacturing processes and some coverage of SMT.

1989 Microelectronics International

doi: 10.1108/eb044379

Janette Rowland has been appointed marketing services manager of General Hybrid. Based at their facility on Tyneside, and reporting to the general sales manager, Ms Rowland is responsible for all PR, marketing support and promotional activities for General Hybrid worldwide. She joins the company from CSM, a software house, where she held the position of marketing executive.

1989 Microelectronics International

doi: 10.1108/eb044380

ElectroScience Laboratories have recently introduced two new mixedbonded ternary conductors that form excellent cermet resistor terminations. Made of platinum, palladium, and silver PtPdAg, ESL 9565 and 9566 are more oxidationresistant during overglaze firing 500525C than more commonly used palladiumsilver PdAg metallisations. Therefore they solder wet more easily after overglazing than with PdAg.