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White Light-Emitting Diode: Fundamentals, Current Status, and Future Trends
Published in Wengang (Wayne) Bi, Hao-chung (Henry) Kuo, Pei-Cheng Ku, Bo Shen, Handbook of GaN Semiconductor Materials and Devices, 2017
Bingfeng Fan, Yi Zhuo, Gang Wang
The other one is wafer-to-wafer wafer-level packaging, named Full WLP. LED wafer is diced into components after all wafer-level packaging processes. Full WLP would give a rise in cost if it decreases the density of LED chips on a wafer, so the chip-size package is needed. That is why full WLP is also called wafer-level chip-scale package (WLCSP). An example of full WLP is shown in Figure 14.21. After chip process, p- and n- electrodes are formed on the epi wafer. Copper wires and pillars are electroplated after interlayer dielectric film being coated and patterned. After an encapsulation film is coated to provide mechanical strength and protection, the sapphire substrate is removed by laser lift-off process. Before device singulation, the phosphor coating is done [66].
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Lau, J. H., Pan, S. H., and Chang, C. Creep analysis of wafer level chip scale package (WLCSP) with 96.5Sn-3.5Ag and 100In lead-free solder joints and microvia build-up printed circuit board. J. Electron. Packaging, 124(2),69,2002
Using Taguchi method to identify the key factors of increasing spacing between the dies during dicing tape expansion
Published in Journal of the Chinese Institute of Engineers, 2019
Wan-Chun Chuang, Wei-Long Chen
In traditional die packaging technologies, such as wire bonding or flip chip, the wafer is diced into individual dies before packaging. However, these packaging techniques increase the volume of the die package. Hence, Wafer-level chip scale packaging (WLCSP) has been proposed to mitigate this disadvantage. The characteristics of this technology are that dicing is done after packaging and testing is completed on the entire wafer. This means that the volume of the packaged die is the same as the original die. However, this technology also has its own difficulties. When picking the die from the tape, the tape needs to be stretched first in order to increase the spacing between dies. This is done to prevent the dies from being too close together during picking, which can lead to collision and rupture, as shown in Figure 1. This study has discussed the movement of expanding the tape to increase die spacing. Figure 2(a) shows the model during expansion, and Figure 2(b) is the corresponding side view of the a-a’ cross-section. As shown, a frame is first used to fix the edge of the tape. Next, the die grip ring moves vertically toward the tape. The tape then expands and stretches, causing the spacing between dies to increase.