In order to investigate how the behavior of fatigue life is affected by the geometry of BGA solder joints, three different kinds of BGA solder joints were chosen, and the fatigue lives of the initial cracks were tested by the isothermal fatigue-test equipment. Furthermore, the nonlinear stress-strain behavior in BGA solder joints was studied by finite element analyses (FEA) . It was found that the analytical results of FEA were affected by the analytical models, and the fatigue lives of the three different joints could be assessed by one master Manson-Coffin's law, when the nonlinear equivalent strain range was used as the estimation parameter, and the strain range was analyzed by a three-dimensional FEA model.

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In this paper, a fault detection method is proposed to detect open faults in a combinational circuit on a printed circuit board with TTL SSI's. In the method, open faults are detected by measuring the quiescent supply current of the circuit. Also a test generation algorithm for the test method is proposed and test input vectors are derived for ISCAS-85 benchmark circuits implemented on printed circuit boards with TTL-LS type SSI's. The result shows that the proposed test method has ability to detect more faults with a smaller number of test input vectors than output logic testing.

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A novel high-frequency MCM with a resin-molded faced-up structure and its fabrication technology based on a composite deep etching and micro-press technology are proposed for the process simplification, reverse side electrode configuration and the warp reduction of Cu substrate. The advantage of this novel technology is confirmed by various test fabrication of MCM substrates with the novel structure. By the introduction of the composite deep etching and micro-press technologies, the following results are achieved: (1) the processing time reduction by a factor of 1/2 and the implementation of lead-less electrode structure, (2) the realization of very thin MCM with less than 0.5-mm thickness. Also, it is shown that the applications of“#”shaped-wall structure separating between modules and a mechanical reformation technique are very useful for the warp suppression of Cu substrates. Reduction of the warp of Cu substrate by less than 30μm is achieved.

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A direct metallization method of a photosensitive epoxy resin was proposed in this paper, for manufacturing of printed wiring board by build up process. The sulfo group, as a cation exchange group, was introduced onto the epoxy resin surface through sulfuric acid treatment. The amount of adsorbed copper ions increased with increasing sulfuric acid concentration, dipping time and temperature. It was 2000nmol/cm² for the sample treated with 14M H₂SO₄ solution at 70°C for 30min. The thickness of the copper thin film formed after the reduction process was estimated to be 150nm. The conductivity of the copper thin film was over 0.004 S/_??_ (below 250Ω/_??_) .

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