High-efficiency and low assembly-dependent chip-scale package for white light-emitting diodes

Huang, Che Hsuan; Chen, Kuo Ju; Tsai, Ming Ta; Shih, Min‐Hsiung; Sun, Chia‐Wei; Lee, Wei-I; Lin, Chien-Chung; Kuo, Hao‐Chung

doi:10.1117/1.jpe.5.057606

Cited by 16 publications

(10 citation statements)

References 34 publications

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“…Using the phosphor concentration of 90% for both CSP and FDCSP can meet the backlight color temperature criteria, which is 10,000 K. The size of CSP mini-LED is 1.5 mm × 1.5 mm × 0.8 mm. The optimization of thickness of CSP phosphor layer and CSP package referred to the previous work [6]. For SMD mini-LED, chip is mounted in a cavity substrate, and phosphor is evenly distributed in the cavity with concentration 10% to meet the 10,000 K backlight color temperature.…”

Section: Ofmentioning

confidence: 99%

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Ultra-High Light Extraction Efficiency and Ultra-Thin Mini-LED Solution by Freeform Surface Chip Scale Package Array

et al. 2019

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In this study, we present a novel type of package, freeform-designed chip scale package (FDCSP), which has ultra-high light extraction efficiency and bat-wing light field. For the backlight application, mainstream solutions are chip-scale package (CSP) and surface-mount device package (SMD). Comparing with these two mainstream types of package, the light extraction efficiency of CSP, SMD, and FDCSP are 88%, 60%, and 96%, respectively. In addition to ultra-high light extraction efficiency, because of the 160-degree bat-wing light field, FDCSP could provide a thinner and low power consumption mini-LED solution with a smaller number of LEDs than CSP and SMD light source array.

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Section: Ofmentioning

confidence: 99%

“…For direct lit backlight system with local dimming function, two types of LED packages are widely used. One is traditional surface-mount device (SMD) LED [5,6], the other is chip-scale package (CSP) [7]. For SMD LED, it is the most popular design.…”

Section: Introductionmentioning

confidence: 99%

Ultra-High Light Extraction Efficiency and Ultra-Thin Mini-LED Solution by Freeform Surface Chip Scale Package Array

et al. 2019

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“…Nowadays, wafer level chip scale packaging (WLCSP) technology has attracted a lot of attention in manufacturing small-size, low assembly dependent, high color rendering, high thermal and electrical conductivities, and high reliable pc-white LEDs, which are called chip scale package LEDs (CSP LEDs) [ 29 , 30 ]. The CSP LEDs produced by the flip chip process were adopted in this study.…”

Section: Test Samples and Experimentsmentioning

confidence: 99%

Photometric and Colorimetric Assessment of LED Chip Scale Packages by Using a Step-Stress Accelerated Degradation Test (SSADT) Method

Qian

Fan

et al. 2017

Materials

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By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED) products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT) in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs), i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively), were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample’s rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs) of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT) depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs.

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“…However, a backlight mini-LED panel requires an optical diffusing distance to ensure good surface luminance uniformity, which prevents an ultrathin backlight module [5][6][7][8]. Use of a dense mini-LED array can reduce the mixing distance; however, this method leads to high cost and a heat dissipation problem [9][10][11]. Another method is to tailor the angular distribution of light so that the light emitted from mini-LEDs can spread out faster.…”

Section: Introductionmentioning

confidence: 99%

Uniform Illumination Realized by Large Viewing Angle of Gallium Nitride-Based Mini-LED Chip With Translucent Sublayer Pairs

Ming²,

et al. 2021

IEEE Access

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The advent of mini-light-emitting diodes (mini-LEDs) represents a recent advancement in display technology. The biggest advantage of mini-LEDs over traditional backlight LED panels is that the LED array facilitates the local dimming of light intensity. This paper presents a large-view-angle (LVA) GaN-based mini-LED chip with batwing angular light distribution. By placing a translucent layer on the mini-LED, the angular light-intensity distribution can be modified from the Lambertian type to that resembling a batwing using translucent sublayer pairs. Compared to conventional mini-LEDs, the proposed mini-LED chip requires fewer LEDs and a shorter light-diffusing distance to maintain good uniformity without additional lens packaging. Further, the increased sublayer pair count in the translucent layer affords an increase in the radiation half-power angle from 137.5° to 173.2°. This increases the half-power angle of the mini-LED array from 47.4% to 89.1%. The findings of this study demonstrate significant potential for use in the development of ultrathin backlight panels, which are finding commercial utility in modern television designs. This work should provide the applications solution in mini-LED backlit and wide color gamut RGB backlight display.

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High-efficiency and low assembly-dependent chip-scale package for white light-emitting diodes

Cited by 16 publications

References 34 publications

Ultra-High Light Extraction Efficiency and Ultra-Thin Mini-LED Solution by Freeform Surface Chip Scale Package Array

Ultra-High Light Extraction Efficiency and Ultra-Thin Mini-LED Solution by Freeform Surface Chip Scale Package Array

Photometric and Colorimetric Assessment of LED Chip Scale Packages by Using a Step-Stress Accelerated Degradation Test (SSADT) Method

Uniform Illumination Realized by Large Viewing Angle of Gallium Nitride-Based Mini-LED Chip With Translucent Sublayer Pairs

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