Void-free underfill encapsulation for flip chip high voltage LED packaging

Author(s):  
Andrew W. Shang ◽  
Xing Qiu ◽  
Jeffery C. C. Lo ◽  
S. W. Ricky Lee ◽  
Fred F. Le
Keyword(s):  
2019 ◽  
Vol 216 (16) ◽  
pp. 1900059
Author(s):  
Zhibai Zhong ◽  
Xuanli Zheng ◽  
Jinchai Li ◽  
Jinjian Zheng ◽  
Yashu Zang ◽  
...  

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Yen-Chih Chiang ◽  
Bing-Cheng Lin ◽  
Kuo-Ju Chen ◽  
Sheng-Huan Chiu ◽  
Chien-Chung Lin ◽  
...  

The GaN-based high-voltage flip chip light-emitting diode (HVFC-LED) is designed and developed for the purpose of efficiency enhancement. In our design, the distributed Bragg reflector (DBR) is deposited at the bonded substrate to increase the light extraction. After the flip chip process, the general current-voltage characteristics between the flip chip sample and the traditional sample are essentially the same. With the help of great thermal conductive silicon substrate and the bottom DBR, the HVFC-LED is able to enhance the power by 37.1% when compared to the traditional high-voltage LEDs. The wall-plug efficiencies of the HVFC-LED also show good droop reduction as high as 9.9% compared to the traditional devices.


2012 ◽  
Vol 220-223 ◽  
pp. 2075-2078 ◽  
Author(s):  
Jian Ming Hong ◽  
Xiao Yun Li ◽  
Ping Juan Niu

LEDs for lighting application are becoming widely adopted due to economic, energy and environmental reasons. LEDs are conventionally powerd by low-voltage DC sources. More and more recent research works have been focusing on an integrated LED chip directly driven by high-voltage DC power supply (HV-LED). The chip structure, the key manufacturing processes and its driving technologies are discussed respectively in this paper, which indicates the advantages of HV-LED including higher luminous efficiency, lower cost and enhanced reliability, and base on this, a HV-LED flip chip is proposed.


2014 ◽  
Vol 2014 (1) ◽  
pp. 000751-000756 ◽  
Author(s):  
Z. Cole ◽  
J. Stabach ◽  
G. Falling ◽  
P. Killeen ◽  
T. McNutt ◽  
...  

In this work, the packaging design and development of a high voltage (> 15 kV), high current (120 A) silicon carbide (SiC) multi-chip power module (MCPM) will be presented. The module implements a MCPM packaging strategy which itself uses subassemblies to reduce manufacturing costs through reworkability. The use of solderless internal connections aids in reducing cost both by simplifying the assembly process as well as enabling a high level of flexibility in the manufacturing process in order to drive down costs by increasing yield. A wire bondless flip-chip die interconnection scheme has been developed in parallel with a more traditional wire bonded method. Both presented approaches utilize a common set of parts with minimal differences due to the divergent portions of each interconnection scheme. Device neutrality in this design ensures that a variety of die types from any manufacturer may be housed in a number of arrangements depending on the requirements of the end-use application without requiring significant redesign effort for each new application or improvement in device technology. The SiC MCPM is constructed using high temperature capable materials, enabling operation at high junction temperatures. This leads to the ability to design a small, low profile module with low parasitic inductances and a small junction to case thermal resistance. A low module thermal resistance makes it possible to significantly reduce the size and complexity of the cooling systems, ultimately, reducing the size of the system. Thus, this novel high voltage SiC MCPM represents a significant step forward in high voltage switching applications. This paper discusses the overall mechanical design of the SiC high voltage MCPM; the three-dimensional finite-element modeling and analysis of the thermal and electrical characteristics of the high voltage power module are also presented.


Author(s):  
L. D. Ackerman ◽  
S. H. Y. Wei

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.


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