applied sciences Article Effect of Different Welding Methods on Flip-Chip LED (FC-LED) Filament Properties Mengtian Li 1, Jun Zou 2,3,4,*, Wengjuan Wu 2,*, Mingming Shi 2, Bobo Yang 2,5, Wenbo Li 3 and Bin Guo 6 1 School of Material Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, China;
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[email protected] (B.Y.) 3 Zhejiang Emitting Optoelectronic Technology Co., Ltd., Jiaxing 314100, China;
[email protected] 4 Institute of New Materials & Industrial Technology, WenZhou University, Wenzhou 325000, China 5 Institute of Beyond Lighting, Academy for Engineering and Technology, Fudan University, Shanghai 200433, China 6 School of Electronics and Information Engineering, Changchun University of Science and Technology, Changchun 130022, China;
[email protected] * Correspondence:
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[email protected] (W.W.) Received: 22 October 2018; Accepted: 7 November 2018; Published: 15 November 2018 Abstract: 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.