Yukihiko Yamashita

Laser Action of Nd-Complex-Doped Polymer Laser Based on Liquid

Nd3+ complex doped polymer liquid laser have been demonstrated and the threshold of the laser was also calculated. The calculation results that a laser media with 2 mm length is suitable for low threshold laser oscillation. We obtained the slope efficiency of 20% and the maximum output energy of 5.3 mJ at the pumping energy of 31 mJ by the method of the side pumping. To the best of knowledge, this is the highest slope efficiency of the bulky laser using Nd3+ complex.

Nd 3+ -TFA:HPDA polymeric microchip laser

We demonstrated a Nd3+ complex doped solid-state polymer laser. The laser threshold was reduced to 334 μJ with a new solid-state host matrix and a short laser cavity. Its low threshold enables LD pumping operation.

High efficient laser action by Nd 3+ complex

We obtained the slope efficiency of 20% and the maximum output energy of 5.3mJ by Nd³⁺ complex laser. To the best of knowledge, this is the highest slope efficiency in bulky lasers using Nd³⁺ complex.

Self-assembly of Sn-3Ag-0.5Cu Solder in Thermoplastic Resin Containing Carboxyl Group and its Interconnection

The self-assembly of solder powder on pads is attractive as a novel interconnection method between chips and substrates. However, the solder used in this method is limited to Sn-58Bi and Sn-52In. In contrast, Sn-3Ag-0.5Cu has been relatively less studied despite its wide use as a lead-free solder in assembling semiconductor packages. Hence, here, polymeric materials incorporating Sn-3Ag-0.5Cu solder powder were investigated for the self-assembly of the solder on pads at temperatures up to 260°C in a lead-free reflow process. The self-assembly of the solder was observed with an optical microscope through transparent glass chips placed on substrates covered with the polymeric materials incorporating the solder powder. Differential scanning calorimetry measurements were performed to confirm the behaviors of the reaction of the resins and the melting of the solder. When epoxy resin with a fluxing additive was used as a matrix, self-assembly of the solder was prevented by the cross-linking reaction. Conversely, when thermoplastic resin containing carboxyl groups was used as a matrix, the self-assembly of solder was successfully achieved in the absence of fluxing additives. The shear strength of interconnection using reflowfilm with lamination was sufficient and significantly increased during the reflow process. However, the shear strength of the reflowfilm showed cohesive failure, possibly because of the brittle intermetallic compounds (Ag3Sn, Au4Sn) network in bulk was lower than that of conventional solder paste that showed interfacial failure after the reflow process with a rapid cooling rate.