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World abstracts of microelectronics and reliability
a Debye-type relaxation of the compensation regions at the grain boundaries, with time constant r ~ 15 ms. Good agreement between theory and experiment is obtained over the 0 to 1500 V bias range.
Lowering manufacturing defects analysis costs. MARTYN MANN. Test and Measurement Europe, 37 (Autumn 1993). Manufacturers handling high volumes of a few PCB types can usually cost-justify an ATE system to monitor production processes and diagnose faults. But even for these companies the cost of test programs and fixtures is high enough to make this approach impractical for short production runs. To handle such situations, sub-contract manufacturer Offshore Electronics, Guernsey, U.K., recently augmented an in-circuit production-test strategy. They adopted a Polar Instruments analog impedance-signature analyzer, significantly reducing the time and cost of component-level diagnosis.
Corrosion of thin film aluminum metallization: eonformal coating materials. J. S. OSENBACHand J. L. ZELL. I E E E Transactions on Components, Hybrids and Manufacturiny Technoloyy, 16(3), 350 (May 1993). We report our results on the THB performance of triple-track-tester (TTT) devices coated with room temperature vulcanized silicon rubber (RTV), silicon resin, silicon polyimide, or silicon gel. Devices with each of these conformal coating materials were aged at 85 C/85~°,; relative humidity (r.h.)/A, where 40 ~ A ~ 400 V, for times up to 14,000 hr. We found that the median time-to-fail was exponentially related to the applied voltage. The median life at 300 V was in excess of 30,000 hr for the silicon gel coated samples, 10,000 hr for the RTV coated samples, 3000 hr for the silicon resin coated samples, and 2000hr for the polyimide coated samples. The difference in the median life times is due to differences in the interface bond strength between the polymer coat and the device surface.
Microcurrent, ultra-miniature switches offer reliable contact. TADASHINAKAMURA.JEE (Japan), 38 (June 1993). The trend toward small, thin and lightweight products now includes the switches that play an important role in electronic equipment. The function, performance and quality of the switches improves every year. With the growing number of electronic switches, there is a large demand for switches that operate on low voltage and microcurrents. In addition to their primary use in computer peripheral devices, switches are serve in many different areas such as office automation (OA) equipment, communication equipment and medical equipment.
Systems adopt advanced technology for testing IC devices. OSAMU YAMADA et al. JEE (Japan), 79 (September
1993). Classifications group ICs by
function and application, resulting in three catagories covering memory ICs, logic ICs and mixed-signal ICs. Testing these devices represents an important and traditionally time-consuming step in semiconductor production. Recently, testing systems have evolved that offer superior reliability and speed. Among the participants in this market, Advantest Corp. markets IC test systems for uses from research and development (R & D) to semiconductor manufacturing. This article outlines the latest trends in test technology, and describes specific semiconductor test systems.
A systematic evaluation of factors influencing TAB inner lead reliability. H. E. EVANS, P. M. HARVEY, J. L. DABROSKI and G. O. DEARING. Circuit World, 19(4), 40 (July 1993). Reliability evaluations for new electronic components and assemblies regularly require extensive test cycles that are both time consuming and costly. Objectives of such test batteries are to identify failure mechanisms and the relationship between these mechanisms and product design or processing features. Optimisation of these critical factors or process steps results in optimised reliability. Statistically designed experiments can facilitate the optimisation process by minimising the amount of testing needed to identify factors affecting reliability, and by providing insight into how these factors can be specified to ensure optimum product design. Designed experimentation was utilised in this study to look at product design and process factors affecting the reliability of inner leads for tape automated bonding (TAB) components. Four factors are considered: outer lead compliancy; chip immobilisation: downset; and tape stiffness and rigidity. Experimental details and results are presented which assess the relative importance of these factors in determining ultimate inner lead reliability, and also provide guidance for final product design considerations.
Printed wiring boards with silver through-holes help lower costs. JEE (Japan), 55 (November 1993). Manufacturers today face rising demands to accommodate densely printed wiring boards while simultaneously lowering costs. Against this backdrop, the market for silver through-hole printed wiring boards is extended into various fields. With annual growth, the market already accounts for 300,000sq.m of boards a month. Such printed wiring boards face continuing expansion in the future. Accordingly, manufacturers will improve the technologies for these boards, develop new models, and apply them in innovative ways.
Integrated circuit production yield assurance based on yield analysis. Z. STAMENKOVICet al. Microelectronics Journal, 24, 819 (1993). The production of modern integrated circuits must be accompanied by control of the critical process steps, modern integrated circuit