Effects of Ultraviolet Wavelength and Ambient Temperature on Reliability of Silicones in InAlGaN-Based Light-Emitting-Diode Package

Kim, Ho Young; Lee, Jong Woo; Jun, Duk Jin; Song, Sung Joo; Oh, Jin Seok; Jeong, Hae Yong; Seong, Tae‐Yeon; Amano, Hiroshi

doi:10.1149/2162-8777/ab7c40

Cited by 4 publications

(6 citation statements)

References 27 publications

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“…24 This can be explained in terms of the increase in the contact (adhesion) area and good adhesion, and absence of delamination (as shown later) due to the rough surface, resulting in better heat transfer and dissipation. This indicates that the adhesion between PCB surface and mold resin is important for the reduction of R th , [25][26][27] which is summarized at Table II.…”

Section: Resultsmentioning

confidence: 92%

“…5). [25][26][27] Figure 7 illustrates far field emission patterns obtained from differently plated samples before and after reliability test, which was performed at 85 °C with 35 mA for 1000 h. For the LED packages with the electroless-plated PCB, the far field emission patterns show that the view angles along the X and Y axes are estimated to be 144.45°and 145.66°, respectively, before the reliability test (Fig. 7a).…”

Section: Resultsmentioning

confidence: 99%

“…It is known that the formation of cracks or delamination of mold resin results in the longer light path inside the packages, causing the light to be trapped and so reducing the view angle. 25,28 The lumen maintenance of differently plated samples that underwent the reliability test as a function of operation time is presented in Figs. 8a and 8b.…”

Section: Resultsmentioning

confidence: 99%

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Effect of the Surface Morphology of Plated Printed Circuit Board on the Reliability of LED Packages

Kim

Song

et al. 2020

ECS J. Solid State Sci. Technol.

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We investigated the effect of the surface roughness of the differently plated printed circuit board (PCB) on the reliability of AlGaInP-based LED packages. The electroless-plated PCB exhibited smoother surface than the electrolytic-plated one. Maximum debonding forces depended on the aspect ratios of hillocks on the plated PCB and voids. Thermo-mechanical maximum stress increased with increasing roughness height. For LED packages with the electroless-plated PCB, thermal resistance (R th ) from junction to PCB was increased by 57.43 K W −1 after operation at 85 °C with 35 mA for 1000 h (reliability test), whereas for LED package with the electrolytic-plated PCB, R th from junction to PCB increased by 4.1 K/W. The temperatures of the chip areas of the electroless-plated and electrolytic-plated samples were 91.3 and 85.3 °C, respectively, after the reliability test. For the electroless-plated and electrolytic samples, the view angles along the X and Y axes were 144.43°and 142.87°, and 143.23°and 145.58°, respectively, after the reliability test. Unlike the electrolytic-plated samples, the electroless-plated samples experienced 4.8% drop in the lumen maintenance and delamination between the mold resin and PCB after operation under the 60 °C/90% relative humidity condition with 35 mA for 1000 h.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Effect of the Surface Morphology of Plated Printed Circuit Board on the Reliability of LED Packages

Kim

Song

et al. 2020

ECS J. Solid State Sci. Technol.

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“…Evidence for silicone cracking was found in UV-14 DUTs after RTOL-1, and dark spots were found in the silicone layer for UV-12 after RTOL-1 but not after RTOL-2. This conclusion is based on general observations and knowledge of the impact of degradation of some silicones under UV radiation [9,[29][30][31][32]; however, confirmation of the impact of silicone yellowing on the high parametric failure rates for these products could not be determined within the scope of this study. For UV-13, the high parametric failure rate during RTOL-1 may be because of the high Tsp value during the first 92 hrs of operation, especially because acceptable RFM values were measured for UV-13 throughout RTOL-2 in which Tsp was much lower.…”

Section: Uv-4 Uv-6mentioning

confidence: 80%

Operating Lifetime Study of Ultraviolet (UV) Light-Emitting Diode (LED) Products

Davis

Rountree

Pope

et al. 2022

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Light-emitting diodes (LEDs) can emit radiation that spans the range from near infrared (IR) to all three bands of ultraviolet (UV) radiation: UV-A, UV-B, and UV-C. This report focuses on LEDs that emit in one of the three UV bands because they have the potential to displace lowpressure mercury vapor (LPMV) lamps in a variety of industrial processes, including ink and adhesive curing, medical procedures, and germicidal disinfection. However, before emerging UV LED technologies can displace LPMV lamps, the efficiency and reliability of these sources must meet the user's expectations in each application. An earlier report focused on the construction and initial performance of commercial UV LED products in radiometric and current-voltage (I-V) tests [1]. This report focuses on the long-term performance and reliability of the same set of commercial products. The intent of this report is to provide to the lighting industry a benchmark of the state of UV LEDs as of mid-2021 when these products were purchased. Understanding the failure modes and failure rates of UV LEDs is important in improving UV product reliability at the LED, lamp, and luminaire level and is critical to developing products with higher efficiency, lower carbon footprint, and significantly reduced environmental impact than LPMV lamps.Operating Lifetime Study of Ultraviolet (UV) Light-Emitting Diode (LED) Products viii maintenance [RFM] was 0.50 or lower). Four products (i.e., UV-3, UV-5, UV-9, and UV-11) did not experience any failures during RTOL-1, but the other nine products had failure rates ranging from 10% to 100%. The most common failure mode was a parametric failure, which accounted for 50 failures during the test. Only seven DUTs failed abruptly, and four out of these seven devices were UV-2 DUTs. These findings demonstrate that there is a wide range of reliability in commercially available UV LED products.Different DUTs of the 13 UV LED products were divided into two groups for RTOL-2 based on their power rating. Group-A, which had If values less than 55 milliampere (mA), was operated for 2,500 hrs during RTOL-2, whereas Group-B, which had If values greater than 100 mA, was operated for 3,000 hrs during RTOL-2. Even though product operation times were longer in RTOL-2 compared with RTOL-1, the cumulative failure rate was lower, as might be expected for the milder stress conditions (i.e., lower If values). A total of 32 failures occurred during RTOL-2 (which is 25% of the total product population): 11 abrupt failures and 21 parametric failures. This finding corresponds to a cumulative failure rate of 25%. Most of the failures during RTOL-2 were concentrated in fewer products; this observation was in contrast to findings from RTOL-1, during which failures were more widespread. For example, during RTOL-2, 7 abrupt failures occurred in the UV-2 DUTs and a greater than 50% parametric failure rate was measured for the UV-8 and UV-14 DUTs. These three products accounted for 22 out of the 32 failures recorded in RTOL-2.Based on this work and combine...

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“…For an LED light source, the package not only mechanically protects the light-emitting chip and circuit but also optimizes the LEE, effectively conducts chip heat, and reduces junction temperature [85]. To reduce costs, LEDs for general lighting use inexpensive and easy-to-process organic resin encapsulation; however, the most prominent problem with using UVC LED encapsulation materials is that organic materials are prone to aging and yellowing under long-term UVC band photon irradiation.…”

Section: Packaging Materials Aging Problemmentioning

confidence: 99%

Perspectives on UVC LED: Its Progress and Application

et al. 2021

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High-quality epitaxial layers are directly related to internal quantum efficiency. The methods used to design such epitaxial layers are reviewed in this article. The ultraviolet C (UVC) light-emitting diode (LED) epitaxial layer structure exhibits electron leakage; therefore, many research groups have proposed the design of blocking layers and carrier transportation to generate high electron–hole recombination rates. This also aids in increasing the internal quantum efficiency. The cap layer, p-GaN, exhibits high absorption in deep UV radiation; thus, a small thickness is usually chosen. Flip chip design is more popular for such devices in the UV band, and the main factors for consideration are light extraction and heat transportation. However, the choice of encapsulation materials is important, because unsuitable encapsulation materials will be degraded by ultraviolet light irradiation. A suitable package design can account for light extraction and heat transportation. Finally, an atomic layer deposition Al2O3 film has been proposed as a mesa passivation layer. It can provide a low reverse current leakage. Moreover, it can help increase the quantum efficiency, enhance the moisture resistance, and improve reliability. UVC LED applications can be used in sterilization, water purification, air purification, and medical and military fields.

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Effects of Ultraviolet Wavelength and Ambient Temperature on Reliability of Silicones in InAlGaN-Based Light-Emitting-Diode Package

Cited by 4 publications

References 27 publications

Effect of the Surface Morphology of Plated Printed Circuit Board on the Reliability of LED Packages

Effect of the Surface Morphology of Plated Printed Circuit Board on the Reliability of LED Packages

Operating Lifetime Study of Ultraviolet (UV) Light-Emitting Diode (LED) Products

Perspectives on UVC LED: Its Progress and Application

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