Two methods for calculating the fracture parameters characterizing interfacial delamination between dissimilar materials in LSI plastic packages with either Cu alloy (Cu-2%Sn) or alloy 42 (Fe-42%Ni) leadframe were studied. One method uses relative displacement method proposed by Yuui et al. to derive stress intensity factor and the other derives the energy release rate of interfacial delamination using Irwin's crack closure method. It was found that the value of total energy release rate G derived from Irwin's crack closure method was consistent with that calculated from stress intensity factors using relative displacement method. In Irwin's crack closure method, it was required that opening and shearing unit load in the computation of local compliance's should be applied to nodes which were located more than onefifth of normalizing length away from delamination tip to avoid oscillatory singular displacement field near delamination tip.

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Adhesion between aluminum nitride (AlN) substrates and plastic parts has an important bearing on the development of the plastic and AlN laminated package. This paper reports the influence of surface shape of A1N substrates on peel-off strength between an epoxy modified polyaminobismaleimide adhesive and the substrates. Although peel-off strength increased when the surface became rougher, values differed according to surface treatment method. Surface roughness of each AlN grain, which showed nanometer order, contributes to the increase of peel-off strength. The change of substrate surface to oxidized phase will also contribute to an increase in peel-off strength. Moreover, decrease of non-polar carbon hydride on the substrate surface facilitates an increase in peel-off strength.

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An experimental study using Kr⁸⁵radioactive tracer techniques is made to determine the initial site of the edge-delamination between dissimilar materials occurring in LSI plastic packages with either Cu alloy (Cu-2%Sn) or alloy 42 (Fe-42%Ni) leadframe under temperature cyclic loading. It is found from the Kr⁸⁵penetration test that the initial edge-delamination is expected to occur at the upper corner of the die pad edge for Cu alloy leadframe packages whereas it occurs at the lower corner of the die pad edge for alloy 42 leadframe packages. Numerical stress analysis on the effect of delamination length on the encapsulant resin cracking in the packages is also carried out. The delamination is assumed to be located along the top surface of the die pad for Cu alloy leadframe packages and along the bottom surface of the die pad for alloy 42 leadframe packages. The results of numerical stress analysis show that, in both Cu alloy and alloy 42 leadframe packages, resin cracking starting from lower corner of the die pad edge becomes more likely to occur and cracking direction changes toward the bottom surface of the packages as the delamination extends.

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The comparison of soldering property and mechanical-thermal fatigue properties was examined about 4series, 10 kind of solder alloy of Pb contained solder and Sn-Ag-Cu series solder alloy. As the results of experiment, Sn-Ag-Cu series solder alloy showed excellent solderability and mechanical properties, and it showed 1.9 times longevity as long as Sn-37Pb solder alloy in temperature cycle test. Moreover, properties of Sn-Pb-X series solder alloy were improved by adding Bi, Ag, and Sb, and it showed 1.19 to 1.25 times longevity in temperature cycle test. Solderability and mechanical properties of In-Pb series solder alloy were poor, but it showed 1.39 times longevity in temperature cycle test. From the above-mentioned results, the important knowledges, concerning improvement of reliability of solder joint of electronic equipment, were acquired.

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High frequency currents on power/ground planes of a digital printed circuit board generate a great amount of electromagnetic noise. On digital printed circuit boards, power and ground planes are used not only for supply of DC power to LSI, but also for return path of high frequency signal current. This paper describes an LSI package that has a decoupling inductor which blocks out high frequency currents, and a bypass capacitor which supplies high frequency currents to the LSI. Electromagnetic radiation noise from the board is reduced significantly by suppressing high frequency currents on power/ground terminals of the LSI package. Furthermore, the relationship between value of the decoupling inductor and the effect of noise reduction is verified theoretically and experimentally.

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A new technology for making multi-layered ceramic substrate have been developed withcopper foil patterning which has brought the best solution to low electrical resistivity wiringsystem. The multi-layers board consists of glass-ceramic substrate, copper inner via and copper foil pattern. This ceramic substrate has been fabricated by the zero X-Y shrinkage sintering process, which can achieve the co-firing system with copper foil and ceramic green sheets. This paper presents the results of our study, the condition of the ceramic green sheet for theforming copper foil wiring pattern and the characteristics of the ceramic substrate and copperwiring system.

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In order to evaluate the fatigue life of Sn-3.5Ag solder, which is the candidate base alloy of the lead free solder, fatigue tests were carried out using smooth specimens at 313K. The strain wave forms were (1) fast-tension and fast-compression, (2) slow-tension and slow-compression, and (3) slow-tension and fast-compression. The strain rate of fast straining was 0.1%/sec and that of slow straining was 0.01%/sec. As a result, the fatigue lives (the number of cycles to the crack initiation) were about 3 times as those of the 63Sn-37Pb solder for the fastfast strain wave and the slow-slow strain wave. On the one hand, the fatigue lives of the slowfast strain wave became the about 1/5 of the symmetrical strain wave.

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