High-Current Photodetectors as Efficient and High-Power RF Output Stages

2006 ◽  
Author(s):  
Keith J. Williams ◽  
David A. Tulchinsky ◽  
John B. Boos ◽  
Doewan Park ◽  
Peter G. Goetz ◽  
...  
Keyword(s):  
High Power ◽  
High Current ◽  
Output Stages

High-Current Photodetectors as Efficient, Linear, and High-Power RF Output Stages

2008 ◽  
Vol 26 (4) ◽  
pp. 408-416 ◽  
Author(s):  
David A. Tulchinsky ◽  
John Brad Boos ◽  
Doewon Park ◽  
Peter G. Goetz ◽  
William S. Rabinovich ◽  
...  
Keyword(s):  
High Power ◽  
High Current ◽  
Output Stages

High-current oversized annular electron beam formation for high-power microwave research

2006 ◽  
Vol 89 (17) ◽  
pp. 171503 ◽  
Author(s):  
I. V. Konoplev ◽  
A. W. Cross ◽  
P. MacInnes ◽  
W. He ◽  
C. G. Whyte ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Power ◽  
High Current ◽  
High Power Microwave ◽  
Annular Electron Beam ◽  
Beam Formation ◽  
Power Microwave

Modeling and Design of High-Power, High-Current-Ripple Planar Inductors

2021 ◽  
pp. 1-1
Author(s):  
Yucheng Gao ◽  
Vivek Sankaranarayanan ◽  
Ercan M Dede ◽  
Yuqing Zhou ◽  
Feng Zhou ◽  
...  
Keyword(s):  
High Power ◽  
High Current ◽  
Current Ripple

Improved Heat Dissipation and Optical Performance of High-power LED Packaging with Sintered Nanosilver Die-attach Material

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001585-001605 ◽  
Author(s):  
Paul Panaccione ◽  
Tao Wang ◽  
Guo-Quan Lu ◽  
Xu Chen ◽  
Susan Luo
Keyword(s):  
Thermal Resistance ◽  
High Power ◽  
Heat Removal ◽  
High Current ◽  
Die Attach ◽  
High Power Led ◽  
Silver Epoxy ◽  
The Difference ◽  
Nanosilver Paste ◽  
The Impact

Heat removal in packaged high-power light-emitting diode (LED) chips is critical to device performance and reliability. Thermal performance of LEDs is important in that lowered junction temperatures extend the LED's lifetime at a given photometric flux (brightness). Optionally, lower thermal resistance can enable increased brightness operation without exceeding the maximum allowable Tj for a given lifetime. A significant portion of the junction-to-case thermal resistance comes from the joint between chip and substrate, or the die-attach layer. In this study, we evaluated three different types of leading die-attach materials; silver epoxy, lead-free solder, and an emerging nanosilver paste. Each of the three was processed via their respective physical and chemical mechanisms: epoxy curing by cross-linking of polymer molecules; intermetalic soldering by reflow and solidification; and nanosilver sintering by solid-state atomic diffusion. High-power LED chips with a chip area of 3.9 mm2 were attached by the three types of materials onto metalized aluminum nitride substrates, wire-bonded, and then tested in an electro-optical setup. The junction-to-heatsink thermal resistance of each LED assembly was determined by the wavelength shift methodology, described in detail in this paper. We found that the average thermal resistance in the chips attached by the nanosilver paste was the lowest, and it is the highest from the chips attached by the silver epoxy: the difference between the two was about 0.7°C/W, while the difference between the sintered and soldered was about 0.3°C/W. The lower thermal resistance in the sintered joints is expected to significantly improve the photometric flux from the device. Simple calculations, excluding high current efficiency droop, predict that the brightness improvement could be as high as 50% for the 3.9 mm2 chip. The samples will be functionally tested at high current, in both steady-state and pulsed operation, to determine brightness improvements, including the impact of droop. Nanosilver die-attach on a range of chip sizes up to 12 mm2 are also considered and discussed.

The Study on LED Accelerated Life Testes and Failure Mechanism

2013 ◽  
Vol 462-463 ◽  
pp. 678-682
Author(s):  
Yue Zong Zhang ◽  
Chun Xia Li ◽  
Wen Bin Zhang
Keyword(s):  
Active Region ◽  
Failure Mechanism ◽  
High Power ◽  
Light Emitting Diode ◽  
Characteristic Curve ◽  
Optical Parameter ◽  
Thermal Parameter ◽  
High Current ◽  
Current Stress ◽  
High Power Led

The paper is studied on the performances of low power light-emitting diode and high power LED under high-current. After observing and measuring the degeneration of them, the Analysis of the failure mechanism is given. The degenerations of the optical parameter, electronic parameter and thermal parameter of high power LED under 600mA current stress are measured and the failure mechanism is analyzed. The I-V characteristic curve proves that the degeneration is happened in active region. Under high-current stress, the active region of high power LED is ageing which leads to much more defects. The degenerations of pins on the resin package, metal wire and surface layer metal pads are found with scanning electron microscope.

Improved Heat Dissipation and Optical Performance of High-Power LED Packaging with Sintered Nanosilver Die-Attach Material

2010 ◽  
Vol 7 (3) ◽  
pp. 164-168 ◽  
Author(s):  
Paul Panaccione ◽  
Tao Wang ◽  
Xu Chen ◽  
Susan Luo ◽  
Guo-Quan Lu
Keyword(s):  
Thermal Resistance ◽  
High Power ◽  
Heat Removal ◽  
High Current ◽  
Die Attach ◽  
High Power Led ◽  
Silver Epoxy ◽  
The Difference ◽  
Nanosilver Paste ◽  
The Impact

Heat removal in packaged high-power light-emitting diode (LED) chips is critical to device performance and reliability. Thermal performance of LEDs is important in that lowered junction temperatures extend the LED's lifetime at a given pho-tometric flux (brightness). Optionally, lower thermal resistance can enable increased brightness operation without exceeding the maximum allowable Tj for a given lifetime. A significant portion of the junction-to-case thermal resistance comes from the joint between chip and substrate, or the die-attach layer. In this study, we evaluated three different types of leading die-attach materials; silver epoxy, lead-free solder, and an emerging nanosilver paste. Each of the three was processed via their respective physical and chemical mechanisms: epoxy curing by cross-linking of polymer molecules; intermetalic soldering by reflow and solidification; and nanosilver sintering by solid-state atomic diffusion. High-power LED chips with a range of chip areas from 3.9 mm2 to 9.0 mm2 were attached by the three types of materials onto metalized aluminum nitride substrates, wire-bonded, and then tested in an electro-optical setup. The junction-to-heatsink thermal resistance of each LED assembly was determined by the wavelength shift methodology. We found that the average thermal resistance in the chips attached by the nanosilver paste was the lowest, and it was highest from the chips attached by the silver epoxy. For the 3.9 mm2 die, the difference was about 0.6°C/W, while the difference between the sintered and soldered was about 0.3°C/W. The lower thermal resistance in the sintered joints is expected to significantly improve the photometric flux from the device. Simple calculations, excluding high current efficiency droop, predict that the brightness improvement could be as high as 50% for the 3.9 mm2 chip. The samples will be functionally tested at high current, in both steady-state and pulsed operation, to determine brightness improvements, including the impact of droop. Nanosilver die-attach on a range of chip sizes up to 12 mm2 are also considered and discussed.

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