Yun Mou

A novel copper-coated ceramic substrate prepared by nano thermocompression bonding

In this paper, we propose a feasible and prospective method to prepare copper-coated ceramic substrate by using nano thermo-compression bonding technology. Nanoporous copper (NPC) can be prepared by dealloying of Cu-Zn alloy system in L-tartaric acid solution. By controlling the concentration of L-tartaric acid solution and dealloying temperature, NPC presents good homogeneity and open bi-continuous interpenetrating ligament-channel microstructures with the average ligament size of 20 nm. In addition, copper-coated ceramic substrates using NPC are successfully prepared under the bonding pressure of 20MPa for 50min at 350°C in the N2 atmosphere resulted in excellent bonding qualities without voids in the bonding layer, the tensile strength reaches 9.2MPa. These testing results confirms that the copper-coated ceramic substrate prepared by nano thermocompression bonding is a feasible and promising technology.

Facile fabrication of microstructured fluoropolymer encapsulation for light extraction enhancement of deep ultraviolet LEDs

In this paper, we present a simple and green approach to economically fabricate microlens arrays (MLAs) on fluoropolymer encapsulation for deep ultraviolet light-emitting diodes (DUV-LEDs). The MLAs can be fabricated by micromolding water condensing based porous films. By controlling the input current and working time of initiative cooling, uniform porous film with the average height of 1.58 µm and the average bottom-width of 1.12 µm was prepared. The MLA with the aspect ratio (AR) of 1.41 was fabricated by micromolding the porous film templates. In addition, the fluoropolymer encapsulation with MLA was applied for the packaging of DUV-LED. Consequently, the light output power of DUV-LED is enhanced of 7.1% by using this MLA at the driving current of 350 mA.

Ultra-compact warm WLEDs fabricated by multi-color phosphor-in-glass directed bonding on flip-chip UV-LEDs

In this paper, we prepared a multi-color phosphor-in-glass (PiG) for the packaging of warm white light-emitting diodes (WLEDs). The multi-color PiG yields a red, green, and blue (RGB) phosphors glass layer, which was screen-printed and co-sintered on a glass plate at the temperature of 600°C. The RGB-PiGs were directly bonded on flip-chip ultraviolet (UV) LEDs. By controlling the thickness of RGB layer, the luminous properties of RGB-PiG based WLEDs are adjusted. When the RGB layer thickness is 75 µm, the RGB-PiG based WLED achieves a warm white light, and the corresponding luminous efficacy (LE), correlated color temperature (CCT), and color rendering index (CRI) are 27.76 lm/W, 4245 K, and 92.6, respectively, at the current of 350 mA. The multi-color PiG provides an effective approach to achieve warm WLEDs with high CRI for display and indoor lighting applications.

Thermally stable multi-color phosphor-in-glass bonded on flip-chip UV-LEDs for chromaticity-tunable WLEDs

In this paper, we propose a thermally stable multi-color phosphor-in-glass (PiG) for chromaticity-tunable white light-emitting diodes (WLEDs). The multi-color PiG has a red, green, and blue (RGB) phosphor glass layer, which was screen-printed and co-sintered on a glass plate with a low temperature of 600°C. The WLED with ultra-compact structure was fabricated by the RGB-PiG directly bonded on a flip-chip ultraviolet (UV) LED. By controlling the weight ratio of R∶G∶B phosphors, the thickness of the RGB layer, and the weight ratio of phosphors to glass powders (PtG), the chromaticity of RGB-PiG based WLEDs can be effectively tuned with high color quality. With the R∶G∶B ratio of 2∶3∶2, the RGB thickness of 75xa0μm, and the PtG ratio of 2∶1, the RGB-PiG based WLED achieves a natural white light with a luminous efficacy (LE) of 27.8xa0lm/W, a correlated color temperature of 4245xa0K, and a color rendering index of 92.6 at the current of 350xa0mA. The LE losses of the RGB-PiG based and RGB phosphor-in-silicone based WLEDs are 4.7% and 14.6% after the aging tests of 1000xa0h at 100°C, respectively. The results demonstrate that the multi-color PiG is a promising converter for UV-excited WLEDs.