We grew a heterojunction combination of Mg-doped Ga-rich InGaN cladding and In-rich InGaN active layers on top of Si-doped GaN nanocolumns with a diameter of 300 nm; the uniformly arranged and dislocation-free GaN nanocolumns contributed to the high crystalline quality of In-rich InGaN, which led to the longest-wavelength (1.46 m) operation of InGaN light emitting diodes. The In content of the active layer estimated from the emission peak wavelength was 0.86. The selected-area diffraction analysis in the transmission electron microscope for the InGaN layers evinced that the In contents of the Ga-rich and In-rich InGaN layers were approximately 0.3 and 0.85, respectively.

In the electronics industry, lead-free solder processes such as the terminal plating of electronic components, fine pitch connectors, and flexible printed circuits (FPCs) are invariably hampered by the serious problem of tin whisker formation. Here, a new and simple method, the JVC Micro Island (JMI) process, is proposed for the prevention of tin whisker formation in fine pitch connectors. Briefly, the base copper terminal was acid etched to afford a roughened surface, which was then tin plated. The contact test with Knoop indentation proved the effectiveness of the present process. The maximum length of the as-formed tin whiskers was less than 50 mm. The solderability of the JMI FPCs was not influenced by the present process. Thus, the new JMI process is shown to have a great advantage for the prevention of tin whisker formation in fine pitch connectors.

We have developed the ultrathin 4-layer flexible printed circuits (FPCs) with the thickness of 135 urn. This 135urn ultrathin 4-layer FPC is made by the molecular bonding technology, by which the electroless plating (metallizing) can be directly applied to polyimide (PI) by using molecular junction agents. In this study, we show the fabrication procedures, the mechanism of direct copper plating, and the reliability verification of the ultrathin 4-layer FPC prototype.