Peel strength of the solder joint was evaluated by using the test specimen which mounted the cut of the build-up printed wiring board on CSP. The amount of displacement grows when peel off in the die-bond layer. Peel strength of the build-up printed wiring board rises compared with the solder alloy layer and die-bond of CSP. The amount of displacement decreases when peel off in the solder alloy layer of CSP and the difference of peel off strength grows. The average value of the destruction energy goes up if the displacement speed rises.

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The warp deformation behavior due to cooling in flip chip attached laminated beams constructed with a LSI chip, an anisotropic conductive film layer and a glass-epoxy resin substrate was calculated by using the thermo-viscoelastic analysis method and elastic analysis method. Although calculated values by elastic analysis method and experimental values were not in accord, the calculated values by thermo-viscoelastic analysis method shows good relationship to the experimental values. It is necessary to use the thermo-viscoelastic analysis method to get the optimum design for not only material properties but constructive layered material to achieve the higher reliable electronics devices.

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Effect of Cu core in BGA solder ball was investigated on the joint shear strength and the microstructural evolution after high temperature storage. When Sn-37Pb or Sn-36Pb-2Ag solder ball without Cu core was used, metastable (Au, Ni) Sn₃ layer with high growth rate was formed on the bondline, which enhanced the formation of Pb layer in the solder. For Cu cored solder, equilibrium (Au, Cu, Ni) ₆Sn₅ reaction layer was formed and suppressed the Ni-Sn interaction. Because of the absence of Pb layer resulted from the slower growth rate of (Au, Cu, Ni) ₆Sn₅ reaction layer, Cu cored solder ball/pad joint was less degraded after high temperature storage.

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We have developed and adopted build-up technology for printed wiring boards (PWB) of notebook PC, which uses via holes that connect 3 layers compared to the normal build-up PWB which used via holes that connect 2 layers. This technology is more superior in electrical characteristics, which enables one to easily control characteristic impedance and reduce crosstalk noise. For the method of manufacturing, we selected laser drilling method and B²it^TM. Although the shape of their vias are different, their electrical characteristics are equal.

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This paper describes the evaluation and the problems of Pb-free joint assembled by the quasi-flow soldering method. The pull strength of the Bi-poor Sn/AgBi solder joint to Bi-poor Sn/Ag/Bi coated electrode compare favorably with those Pb/Sn joints. However, Sn/Ag/Bi more than 5 weight % Bi joints shows cracking at the solder/Cu interface. As a results, the pull strength and reliability of Bi poor joints less than 3 weight % shows good characteristics as a Pb-free joint.

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