To improve the solder joint reliability of Pd/Au layer formed on Cu substrates, the effects of additives added to Pd-catalyst treatment solutions on the solder joint reliability were examined. As additives, ammonia, ethylenediamine-N,N,N',N'-tetraacetic acid dipotassium salt（EDTA･2K）, glycine, ammonium molybdate tetrahydrate （AMTH）, and sodium hypophosphite （SHP） were used. Surface and cross-sectional scanning electron microscopic observations were made of the Cu substrates after treatment with Pd-catalyst treatment solutions. Furthermore, Pd layers formed on the Cu substrates and electrochemical measurements of the Pd/Cu were examined to verify the degree of surface treatment of the Cu surface with the Pd-catalyst treatment solutions and the formation of voids and pinholes in the Cu/Pd interfaces and Pd layers. After a Au layer was deposited on the Pd layers, the Cu/Pd/Au solder joint reliability was evaluated by measuring the shear strength of the solder formed on the Au layers. The solder joint reliability test results showed that the SHP additive can improve the Pd/Au layer solder joint reliability. The Cu and Pd surfaces treated with the Pd-catalyst treatment solutions containing SHP were flat among those prepared with other additives. The number of voids around the interfaces between Cu and Pd layers in the case of SHP was the lowest among the additives examined. It can be inferred that the suppressed void formation contributed to improvement of Pd/Au layer solder joint reliability.
The ZnO vertical nanowires and layers were prepared by electrodeposition in aqueous solutions containing zinc nitrate hydrate and zinc chloride hydrate with total Zn concentration set at 0.8, 8, and 80 mmol/L with the zinc chloride hydrate molar ratio of 0 - 10 mol%. Their electrochemical, structural, and electrical characteristics were investigated with electrochemical measurements including a Mott-Schottky plot, X-ray diffraction, SEM observation, and optical transmission spectra measurements. The <0001>-oriented ZnO nanowires with 3.3 eV bandgap energy and <0001>-oriented ZnO layers with 3.4 eV bandgap energy were prepared in 0.8, 8, and 80 mmol/L solutions. The growth rate for the ZnO nanowires was 44 nm h－1 at the total Zn concentration of 0.8 mmol/L and zinc chloride molar ratio of 0.1 mol%（0.8 mmol/L - 0.1 mol%）increased to 290 nm h－1 at 8 mmol/L - 0.1 mol%. The ZnO nanowires width increased from 40 nm at 0.8 mmol/L - 0 mol% to 285 nm at 8 mmol/L - 10 mol% with increases in both the total Zn concentration and zinc chloride molar ratio. The carrier concentration of ZnO nanowires and layers increased to maximum values at around 0.1～1 mol% with the increase in the zinc chloride molar ratio, and decreased at 10 mol%. The change affected the growth rate. Also, the change in the width of the ZnO nanowires and layer was related to the zinc chloride molar ratio because of change in the ZnO crystal growth direction.