The development of fibre optic systems for industrial applications

this fibre system. We shall describe the laser source, the design concepts of the package.and its construction and performance. The flexibility of this packaging concept will be emphasised by reference to related packages which allow high temperature usage and integral circuitry. The develol~ment of Fibre Optic systems for industrial application.~ D. W. H A R P E R Fibre-optic systems are rapidly becoming accepted in a wide variety of industrial applications. Until quite recently the much better known applications in national telecommunications networks received most attention. However during the last year many industrial installations have been carried out and the value of fibre-optic systems is now more widely appreciated. In many respects the publicity given to fibre-optic comp~ development for telecommunications has discouraged industrial users. In telecommunications the objective is to transmit large information bandwidths (e.g. 140 Mb/s) over great distances (>I0 km) without repeating stations. This has been acheved with a consequent high degree of sophistication in connectors, active devices and coupling techniques. For the industrial user, where distances and bandwidths are less (e.g. 10-2000 metres, perhaps 10Mb/s), the sophistication in components is unnecessary and costly. The reasons fQr an industrail user choosing fibre-optic systems can be quite different from those in telecommunications. Furthermore because of the nature of industrial systems a different set of rules for component development and selection can be evolved. Pin-Fet receivers for 1.3 micron fibre optic systems J. W. BURGES, A. W. MABB I'IT and K. L. MONHAM The development of ultra-low-loss optical fibres together with zero in-material dispersion at 1.3 microns I and the realisation of suitable high power, high speed LED soures and high sensitivity PIN photodiode receivers will enable the fabrication of long haul, high data rate links using these components rather than lasers and avalanche detectors (APD), which have been traditionally viewed as essential components for such systems. High launch powers have been obtained from LEDs by coupling efficient double heterostructure devices into fibres using microlenses, a technique which can give improvements of up to 30 times over butt-coupled sources z. High speeds have been achieved by controlled doping of the active layer and by selection of the active region geometry. The attainment ofSi PIN-FET receivers with sensitivities approaching that obtained in Si APD receivers has been demonstrated ~. As the excess noise performance of long wavelength (> 1.1 micron) APDs is now universally recognised as being considerably inferior to that obtained in Si APDs, then the PIN-FET approach applied to 1.3 micron detection would be expected to be the optimum receiver design approach. 5.

Hybrids

Significant features of solder connections to gold-plated film~ H A R R Y N. KELLER

An investigation of 60Sn-40Pb solder connections between phosphor-bronze clip-on terminals and Ti-Pd-CuNi-Au and Ti-Pd-Au thin film terminations is described. The investigation consisted of measuring joint strength and analysising resultant fracture interfaces and metallographic cross-sections by manning electron microscope - energy dispersive X-ray analysis (SEM-EDAX), electron-microprobe (EMP), and X-ray diffraction, both intially and after accelerated temperature aging. Similarities and differences bbserved for the differet terminals and termination conductors used in this, and previous investigations, are presented. Observations are explained by termination interdiffusion, intermetallic compound formation between terminal, termination, and solder constituents, and joint geometry related to the terminal design. Thick film materials and reliability P. W. G R A V E S Electl Commun. 57 (2), 127 (1982). Detailed investigation of conductor, resistor, and insulator inks is essential if the reliability of hybrid circults is to be assured. Comprehensive facilities at Standard Telecommunication Laboratories allow existing materials to be studied and the potential of new ones to be assessed rapidly. New thick film multilayer interconnection technology using a Nd-YAG laser TAKAAKI OHSAKI, ETSUJI SUGITA and SATORU YAMAGUGHI

IEEE Trans. Components ttybrids mfg Technol. CHMT-5 (4), 382 (1982). The mechanism and capability of the new thick film multilayer interconnection technolgoy 9using a neodymium-doped yttrium aluminium garnet (Nd-YAG) laser have been theoretically and experimentally described. The mechanism for the conductor pattern formation involves the softening phenomenon of the glass and the thermosetting phenomenon of the organic binder, contained in a thick film conductor paste, by continuous wave (CW) laser beam energy. In the via hole formation, small holes can be drilled by a pulsed laser beam without damage to the under conductor layer, because at constant peak power drilling rate per shot decreases with the increase in depth, that is, with the increase in the number of shots. The conductor size and via hole size formed by the new technology are mainly affected by the laser beam diameter. The minimum beam diameter is limited by the melting phenomenon of a conductor metal for the conductor formation and the substrate tolerance for the via hole formation. Possible conductors and via holes are 25-pm wide with 10-~m thick gold 18-p.m diameter with 30-/zm thick crystallizable glass, respectively. A ceramic capacitor substrate for high speed switching VLSi chips D U D L E Y A. CHANCE, CHUNG-WEN HO, C H R I S T O P H E R H. BAJOREK and M I C H A E L SAMPOGNA

IEEE Trans. Components Hybrids mfg Technol.

CItMT-5 (4), 368 (1982). An integrated capacitor substrate which is proposed as IEEE Trans. Components Hybrids mfg Technol. an essential part in the realization of a th{n film for high CHMT-5 (4), 408 (1982). speed digital computing systems is discussed. Several 40