Regarding effects of Electroless Nickel/Immersion Gold (EN/IG) on BGA solder joints, pull strength of solder balls on the substrates plated by several kinds of EN/IG were evaluated using hot bump pull test. Furthermore, each surface structure of EN and IG plating was observed by SEM/EDX and the interfaces of BGA joints were analyzed by EPMA. It was found that the process of EN producing low-phosphorous content deposit and IG plating that hardly deteriorated nickel surface was better for BGA solder joints. It seemed that BGA solder joint was destructed at the interface between Ni-P and Ni-Sn intermetalic layer.

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Photosensitive-Crystallizable glass (PC-glass) is expected to be applied widely in electronics field because it forms three-dimensional and complicated shape easily. Conductive films on glass have been formed conventionally by dry process. However, it is very difficult to obtain the uniform metal deposition on the third-dimensional configuration by dry process. In our investigation, PC-glass surface morphology after etching and adhesion of copper plating films on a glass substrate are examined. The glass surface was appropriately roughened by fluoride-based etchant to improve the adhesion strength between glass and copper plating film. The etching characteristics were entirely different from crystallization conditions. Amorphous and fully crystallized PC-glasses were provided to obtain the proper etching morphologies for improvement of the adhesion strength between copper plating films and glass. Under fully crystallized condition, formation of anchor sites was created by the treatment in dilute hydrofluoric acid, and adhesion strength between copper plating films and glass surface was around 1.7kgf/4mm². Excellent adhesion strength is derived from the anchor effect that is created by the preferential etching at Li₂O·SiO₂ riched parts in crystalline substrate.

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The thermal cycle test was performed to CSP microjoints with several Sn-Ag lead-free solders, and the microstructure observation was performed before and after thermal cycle test. In the initial solder joints with Sn-3.5Ag or Sn-3.5Ag-0.76Cu, fine Ag₃Sn grains were mainly distributed at the grain boundary of Sn and around there. Those grains formed the network structure in the Sn matrix. After thermal cycle test, a spherical growth of Ag₃Sn grain was observed and the network structure was disappeared. In that microstructure, the crack growth was relative fast. On the other hand, as for Sn-Ag-Bi-Cu alloy, Bi phases were finely existed in Sn matrix and those were stable even after the thermal cycle test. The crack growth in Sn-Ag-Bi-Cu solder was relative slow because of the stable microstructure.

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We propose a simple and flexible fabrication technique of waveguide components in nonlinear polymer thin films. Using electron-beam direct writing technique, we fabricated a submicron χ ⁽²⁾ grating. Moreover, a channel waveguide structure, and an out-of-plane branching mirror structure are formed.

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This paper describes a new approach to a reversible interconnection for environmentally conscious engineering in electronics. The reversible interconnection is a bonding method, which is designed for separating the joint to each material at the bonded interface. To demonstrate the concept of the reversible interconnection, separation was executed by using a hydrogen storage alloy as an insert material. The hydrogen storage alloy is well known to pulverize by hydride formation. The separation of the joint has been successfully carried out by self-col-lapse of the hydrogen storage alloy under hydrogen atmosphere.

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Ceramic substrates with buried capacitors were studied. Miss-matchings of sintering behaviors between substrate layer, capacitor layer and barrier. layer were canceled by adapting zero X-Y shrinkage sintering method. Newly developed barrier layer of MgO-ZnO-PbOCuO composition prevented a reaction between substrate layer and capacitor layer. Byusing these techniques, buried capacitance of 1μF/cm²have been developed.

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We have newly developed fluid-assisted self-aligned assembly technique using Au-Sn solder bump re-flow in assembling multi-channel optical devices in integrated multi-channel optical modules. Packaging throughput has been improved by using this technology because initial offset tolerance in placing optical chips before re-flowing solder bumps has been relaxed and necessity of ambient control has been eliminated. We applied this technology to a hybrid-inte-grated eight-channel SOAG (semiconductor optical amplifier gate) array module and sufficient performance for optical gate systems have been obtained.

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