Au-Ni plated Cu pads were reflow soldered by using lead free solder balls. The microstructure and strength of the as-reflowed solder joints were investigated. For solder joints using Cu-free Sn-Pb and Sn-Ag solder balls, a Ni 3 Sn 4 reaction layer was formed on the boundary between solder and pads. On the other hand, a Cu-Sn based (Cu, Ni) 6 Sn 5 reaction layer (η ) was formed in solder joints using Cu-containing solder balls. The growth rate for an η reaction layer during heat exposure at 423 K was much slower than that for a Ni 3 Sn 4 reaction layer. This suppression of an η reaction layer growth can be attributed to the fact that the Cu in solder balls was mostly removed during the formation of the η layer. By ball shear test, cold bump pull and hot bump pull tests, mechanical properties of the obtained BGA joints were investigated. Fracture loads and crack propagation path changed by changing the mechanical tests, the BGA joints using Cu containing Sn-Ag-Cu solder or low P type Ni plating revealed better mechanical properties. We established the mismatch of the boundaries between reaction layers and the P-enriched Ni-P layer, which was caused by the chained voids formed due to the Kirkendall effect, led to low joint strength.

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We developed a microfluidic chip for automation of cloning process based on a new protocol. The protocol is based on removal of the zona pellucida outside the chip which contributes to simplify on-chip automation of cloning. Then, the oocytes are put into the chip. The design concept of the chip is summarized as follows. (1) The oocyte is cut into two parts. (2) The divided half oocyte is sorted with and without nucleus. (3) The half oocyte without nucleus is coupled with a donor cell, and (4) they are fused by an electrical field. For the current study, the all-in-one unified microfluidic chip was designed to execute (1) cutting, (2) sorting, and (3) coupling parts continuously for this process. Basic functions of these parts as well as fusion part are verified independently. Then, all-in-one unified microfluidic chip was successfully designed and fabricated.

We developed a chip for automation of cloning based on a new protocol of cloning. The protocol is removal of the zona pellucida at first stage which contributes to simple on-chip manipulation for automation of cloning. The cloning chip was designed to have 3 parts working for manipulation of oocyte and donor cell. The concept of design is summarized as follows. (1) The oocyte is cut into two parts. (2) The divided half oocyte is sorted with and without nucleus. (3) The half oocyte is coupled with a donor cell, and the coupled oocyte and donor cells are fused by an electrical field. For the current study all-in-one unified microfluidic chip was successfully fabricated for automation of cloning based on the new protocol using micro-robotics.