Thick Film Superconductors Based on Bi2O3 Modified YBaCuO and BiSrCaCuO SystemsHrovat, 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.
PriceDensity Tradeoffs of Multichip ModulesMessner, 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.
The Optimal Choice of High Pin Count ASIC PackagesGustafsson, 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.
The Possibilities for Applying Superconductive Ceramics to HMT Hybrid Microelectronics TechnologyMiyashiro, 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.
A Thick Film Materials System for the Manufacture of Advanced Hybrid MicrocircuitsGee, 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.
Will ASIC Technology Demand a New Interconnection Technology instead of Soldering in Automotive ElectronicsDanielsson, 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.
Glass Ceramics An Alternative Substrate for Microwave Integrated CircuitsWhatley, 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.
W.C. Heraeus GmbH, Hanau, West Germany1989 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.
EMCA, Linton, Cambridge, England1989 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.
ISHM news1989 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.
Industry news1989 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.
New products1989 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.