Owing to its stability and environment-friendly properties, the SrAl2O4:Eu2+, Dy3+ (SAOED) phosphor has attracted major scientific interest.

Bismuth silicate Bi 4 Si 3 O 12 (BSO) crystal is a fast scintillator which has potential applications in high energy physics, nuclear physics, computed tomography and dosimetry. Compared with widely used Bi 4 Ge 3 O 12 (BGO) crystal, BSO has some better scintillation properties such as a faster decay time, greater radiation hardness and a lower raw material cost, so it is considered to be the substitute for an alternative to BGO crystals. However, two main problems hindered its practical applications: (1) it is difficult to grow large size and high quality crystals due to its compositional segregation; (2) BSO has a relatively low light yield. Recently, large size BSO crystals have been grown by the modified vertical Bridgman method in Shanghai Institute of Technology. The scintillation properties of rare earth doped BSO crystals have been investigated and BSO crystal doped with small amount Dy 2 O 3 increases its light yield remarkably. Furthermore, some experimental results revealed the potential applications of Re-doped BSO crystals in laser and LED fields. In this review, the growth process, scintillation properties and luminescent mechanism of Re or Ge doped BSO crystals were introduced. The spectroscopic properties and energy transfer of Re-doped BSO crystals were discussed based on its applications in laser and LED. As a result, doped BSO crystal is a novel multi-functional material for scintillation, laser and LED applications.

This paper investigates the effect of soldering temperature on solder joint voids and reliability of flip-chip LED chips during reflow soldering. Lead-free solder SAC305 was used as solder paste. The void ratio of the flip-chip LED solder joint at 250°C, 260°C, 270°C, 280°C, and 290°C reflow soldering temperatures was detected by x-ray detector. Shear tests were conducted to evaluate the influence of interfacial reactions on the mechanical reliability of solder joints. The distribution of voids in the shear section was observed by scanning electron microscope (SEM). Next, the photoelectric and thermal properties of FC-LED filament were tested and analyzed. Finally, a hightemperature and high-humidity aging experiment was carried out to test the reliability of the LED filament. The results show that the void ratio of the LED filament soldering joint is the lowest when the soldering temperature is 270°C. The small void ratio of the solder joints results in lower steady-state voltage and junction temperature of the flip-chip LED filament. As the void density in the solder joint decreases, the shear strength of the solder joint increases. At this time, the shear resistance and mechanical reliability are the highest.

This paper investigates the effect of two different welding methods, direct welding (DW) and vacuum furnace welding (VFW), on flip-chip light-emitting diode (FC-LED) filament properties. Shearing force, SEM, steady-state voltage, steady-state luminous flux, and change of photoelectric performance with aging time were employed to characterize the differences in filament properties between the two welding methods. The shearing test revealed that the average shearing force of the VFW group was higher than that of the DW group, but the two groups followed the standard. Furthermore, the microstructure of the VFW group fault was more smoother, and the voids were fewer and smaller based on the SEM test results. The steady-state voltage and luminous flux revealed that the VFW group had a more concentrated voltage and a higher luminous flux. The aging data revealed that the steady-state voltage change rate of both groups was not very different, and both luminous flux maintenance rates of the VFW group were higher than those of the DW group, but all were within the standard range. In conclusion, if there is a higher requirement for filament in a practical application, such as the filament is connected in series or in parallel and needs a higher luminous flux, it can be welded using vacuum furnace welding. If the focus is on production efficiency and the high performance of filaments is not required, direct welding can be used.