[in Japanese]

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[in Japanese]

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[in Japanese]

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The following report is not the result of extensive scientific research. It rather presents a subjective impression of the status of occupational safety, Which the author could gain during a year from 2001 to 2002 as a visiting professor for Safety Engineering at Nagaoka University of Technology (NUT), Nagaoka, Niigata.

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[in Japanese]

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The long-term stability of p-Si and c-Si photovoltaic modules manufactured in the 1990's has been studied. About 2,000 modules were investigated after nearly 10 years of exposure. About 150 modules out of these were evaluated by indoor I-V measurements. An average performance loss of less than 0.5%/year was estimated. We found three dominant degradation modes which are main problems for achieving 30-year life time; (1)visual defects caused by delamination between the cells and the potant and two modes without visual features. (2)One is accompanied by a decrease in the fill factor (FF), and (3)the other is accompanied by a decrease in both the short-circuit current (I_<SC>) and the open circuit voltage (V_<OC>). Destructive analyses of modules with degraded FF were conducted.

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In this article we present a new method of inference for the three-parameter Weibull distribution. The method enables us to estimate only the shape parameter independent of the location and scale parameters. The methodology is helpful because the difficulty of estimation of the Weibull parameters is dependent on the existence of the location parameter. A simulation study shows that in the case that the location parameter γ is equal or close to zero, the estimator proposed by us is better than MLE for two-parameter Weibull distribution. The simplicity of the method is shown by an example.

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In recent years of LSI industry, much improvement had been applied onto the mounting reliability of CSP with consideration of evaluation methods, and resulted in the standard "Environmental and endurance test methods for CSP ・ BGA package on mounting condition"(EIAJ ET-7407;1999) finally. Through the years, we verified and improved our test methods in cooperation with customer (user) and packaging manufacturer, and evaluated various kinds of CSP from the viewpoint of the both sides. Validating the improvement of evaluation method for the mounting reliability of CSP, in this paper, we emphasize the importance of reliability built-up by cooperation and sharing information with customer and supplier in newer products and mount technologies.

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