Light Outputs of LED with Various Refractive Indices and Geometrical Structures of Encapsulants

김경태,조경우,황정하,권호기,박시현 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.61

In this paper we present the results of experiments and simulations for the light output power from LEDs for various refractive indices and the geometrical structures of the LED encapsulants. InGaN-based LED chips were fabricated and were bonded in Ag reflector cups within polyphthalamide (PPA) chip carriers; then, encapsulants with various refractive indices and the geometrical structures were fabricated onto them by using a dispensing method. The light output power with the encapsulant was shown to increase with the refractive index of the encapsulant materials in the case of a spherical encapsulant while it decreased in the case of a flat geometry encapsulant. We performed ray tracing simulations for the LED light output and confirmed that the simulation results were consistent with our experimentally measured results. In addition, the light output with the encapsulant rapidly increased with the sidewall angle of the chip carrier in the case of the flat encapsulant while it was not affected by the sidewall angle, remaining constant, in the case of the spherical geometry.

Sol–Gel Derived Transparent Zirconium-Phenyl Siloxane Hybrid for Robust High Refractive Index LED Encapsulant

Kim, Yong Ho,Bae, Jun-Young,Jin, Jungho,Bae, Byeong-Soo American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.5

<P>We report a zirconium-phenyl siloxane hybrid material (ZPH) that can be used as a robust LED encapsulant. The ZPH encapsulant was fabricated via hydrosilylation-curing of sol–gel derived multifunctional (vinyl- and hydride-functions) siloxane resins containing phenyl-groups and Zr–O–Si heterometallic phase for achieving a high refractive index (<I>n</I> ≈ 1.58). In thermal aging, the ZPH LED encapsulant exhibited superior performances with a high optical transparency (∼88% at 450 nm) and exhibited high thermal stability (no yellowing at 180 °C for 1008 h), compared to a commercial LED encapsulant (OE-6630, Dow Corning Corporation). This suggests potential for ZPH to be a robust LED encapsulant.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-5/am500315y/production/images/medium/am-2014-00315y_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am500315y'>ACS Electronic Supporting Info</A></P>

Thermal Curing Property of Silicone Encapsulant Containing Quantum Dot Surrounded by Various Types of Ligands

Lee, Chae Sung,Kim, BeomJong,Jeon, Seongun,Han, Cheul Jong,Hong, Sung-Kyu Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.12

In this study, the silicone thermal curing degree of the silicone-encapsulated quantum dot light emission diode was measured using the various types of chemical ligands around quantum dot. It was confirmed that the trioctyl phosphin oxide (TOPO) ligand around the quantum dot was responsible for dispersion of the quantum dot in silicone encapsulant and decline of the thermal curing degree of the silicone encapsulant. Also, it was confirmed that the thermal curing degree of silicone encapsulants containing the steric acid (SA) and the dodecanoic acid (DA) ligands were higher than the one of TOPO ligand.

Thermal Curing Property of Silicone Encapsulant Containing Quantum Dot Surrounded by Various Types of Ligands

Chae Sung Lee,BeomJong Kim,Seongun Jeon,한철종,홍성규 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.12

In this study, the silicone thermal curing degree of the silicone-encapsulated quantum dot light emission diode was measured using the various types of chemical ligands around quantum dot. It was confirmed that the trioctyl phosphin oxide (TOPO) ligand around the quantum dot was responsible for dispersion of the quantum dot in silicone encapsulant and decline of the thermal curing degree of the silicone encapsulant. Also, it was confirmed that the thermal curing degree of silicone encapsulants containing the steric acid (SA) and the dodecanoic acid (DA) ligands were higher than the one of TOPO ligand.

TiO₂ 나노입자가 혼합된 봉지재를 적용한 LED 패키지의 광효율 특성 평가

이태영,김경호,김미송,고은수,최종현,문경식,김목순,유세훈,Lee, Tae-Young,Kim, Kyoung-Ho,Kim, Mi-Song,Ko, Eun-Soo,Chio, Jong-Hyun,Moon, Kyoung-Sik,Kim, Mok-Soon,Yoo, Sehoon 한국마이크로전자및패키징학회 2014 마이크로전자 및 패키징학회지 Vol.21 No.3

본 연구에서는 $TiO_2$ 나노입자를 LED패키지의 봉지재인 실리콘에 분산시키고, 이에 따른 굴절률, 투과율 및 광효율 변화를 평가하였다. $TiO_2$ 나노입자는 LED 봉지재의 굴절율을 증가시켜 LED 패키지의 광추출 효율을 향상시키기 위해 봉지재에 적용되었다. $TiO_2$는 수열합성법을 통해 합성되었고, 합성된 $TiO_2$ 입자에 긴 체인구조의 vinyl silane을 코팅하여 분산시켰다. 분산 처리를 실시한 후에는 대부분의 $TiO_2$ 나노입자가 10~40 nm 이하로 분산되었으나, 100 nm 이상의 긴 입자도 관찰되었다. 실리콘 봉지재에 $TiO_2$ 나노입자 양이 증가할수록 굴절율은 증가하였으나, 투과율은 감소하였다. $TiO_2$ 나노입자가 포함된 실리콘 봉지재로 LED 패키지를 제조하였고, $TiO_2$ 나노입자가 분산된 LED가 $TiO_2$ 나노입자가 없는 LED패키지에 비해 약 13% 이상 광효율이 향상되었다. $TiO_2$-nanoparticle-dispersed silicone was applied to a LED package and the light efficiency of the LED package was evaluated in this study. The addition of $TiO_2$ nanoparticles in silicone increased refractive index, which improved the light efficiency of the LED package. The $TiO_2$ nanoparticles were fabricated by hydrothermal synthesis and were dispsersed by a vinyl silane coating treatment. After the silane treatment, the $TiO_2$ nanoparticles dispersed with diameters of 10~40 nm but rod-shape $TiO_2$ nanoparticles with lengths of 100 nm were also observed. The refractive index increased with the $TiO_2$ concentration in silicone, while the transmittance decreased with the $TiO_2$ concentration. The light efficient of the LED package with $TiO_2$+silicone encapsulant was higher than that of the LED package with no $TiO_2$ in silicone encapsulant.

Organosilicon LED Encapsulants Based on Polysiloxane and Polysilazane

은희천,허태환,곽영제,Eun, Hee Chun,Huh, Tae-Hwan,Kwark, Young-Je The Korean Fiber Society 2018 한국섬유공학회지 Vol.55 No.3

A mixture of polysiloxane (PSO) and polysilazane (PSZ) was used to prepare a crosslinked organosilicon material for use as an LED encapsulant. The crosslinking was conducted by using two different chemistries: platinum-catalyzed hydrosilylation and peroxide-initiated radical reaction. Successful crosslinking was confirmed by FT-IR spectroscopy, which showed decreased intensities of vinyl ($3,100cm^{-1}$) and hydrosilane ($2,140cm^{-1}$) peaks. The prepared films showed high transparency (>90% at 400 nm) because of the high compatibility between PSO and PSZ. The crosslinked organosilicon films showed higher hardness values when both PSO and PSZ were used at the same time, indicating higher crosslinking density.

Thermal Fatigue Life of Underfilled $\mu\textrm$ BGA Solder Joint

Kim, H.H.,Han, S.W.,Kim, H.I.,Choi, M.,Shin, Y.E. The Korean Welding and Joining Society 2004 International journal of Korean welding society Vol.4 No.1

In this paper, the effect of underfill packages was investigated by numerical approach and experimental test. Reliability improvement was the main issue in the package technology. BGA, CSP and small-sized packages, have problems due to concentration of the stress in solder joints. One of the latest technologies to overcome is underfill encapsulant. Mainly, it is noticed the effect of the underfill in the packages. The predicted thermal fatigue lifes are performed by Coffin-Manson's equation with ANSYS (v.5.62). Also, thermal cycle test during from 218K to 423K was included. Finally we could find that underfill greatly reduce the concentration stress in solder joint, thus the fatigue life was improved than without underfill.

태양전지 봉지재용 에틸렌 비닐 아세테이트 공중합체 필름의 광열화 거동

김문호(Mun Ho Kim),엄효상(Hyo Sang Eom),변두진(Doo-Jin Byun),최길영(Kil-Yeong Choi) 한국고분자학회 2016 폴리머 Vol.40 No.3

본 연구에서는 태양전지 봉지재로 사용되는 ethylene/vinyl acetate (EVA) 필름 소재의 광열화 거동을 분석하였다. 광열화 실험에서는 태양광 하에서의 광열화를 모사하는 것이 중요하기 때문에 태양광과 유사한 제논 아크 램프를 사용하여 실험을 진행하였다. 소재의 광열화는 표면에서 주로 발생하기 때문에, 표면의 형상 및 조성, 그에 따른 광학특성의 변화를 분석하였다. 광열화가 진행되면 EVA 필름의 표면에 미세 크랙과 같은 결점들이 생성됨을 확인하였는데, 이러한 표면 형상의 변화는 광투과 특성에도 영향을 미쳐서 전체적인 광투과가 감소하였다. 또한 광산화반응으로 소수 특성을 유지해야 할 필름의 표면에 친수기들이 생성되어, 태양전지 모듈의 성능 및 수명에 주요한 영향을 미칠 수 있음을 확인하였다. 마지막으로 광원의 차이에 따른 광열화 거동을 분석하여, 가속시험 설계를 위한 광원 선택의 중요성을 확인하였다. In this study, we investigated the photodegradation behavior of an ethylene/vinyl acetate (EVA) film for solar cell encapsulant. The EVA film was exposed to the weathering apparatus, equipped with a xenon-arc lamp for simulated sunlight exposure conditions. Since photodegradation mainly induces changes and variations on the materials surface, a variety of technical approaches were employed to characterize the modifications of the EVA film surface, and then the deterioration behavior of optical properties was discussed in term of the morphological changes. And also, photodegradation caused the composition modification of the EVA film surface by the incorporation of oxygen to the polymer chains, which could make the wettability of the film hydrophilic. Finally, the photo-induced deformation behavior of the EVA film influenced by the light intensity depending on the type of lamp was discussed in order to show the importance of the light source.

표면 처리된 중공 형태 유리 마이크론 입자가 포함된 폴리프로필렌/에틸렌-프로필렌-디엔 복합체의 음향 호스 응용

조민현(Min Hyun Cho),조용준(Yong Jun Cho),김창근(Chang Keun Kim) 한국고분자학회 2015 폴리머 Vol.39 No.4

해수에서 사용되는 음향 탐지 시스템의 장기간 운용을 위해서는 음향 호스 소재로 우수한 기계적 물성과 충진 오일과 해수에 의한 낮은 팽윤도를 갖는 소재가 요구된다. 이층 구조의 음향호스의 외피 소재로 폴리프로필렌/에틸렌-프로필렌-디엔(PP/EPDM) 블렌드에 중공 형태 유리 마이크론 입자(HGM)가 포함된 복합재료를 실험하였다. 보다 향상된 물성의 복합재료를 개발하기 위해 아민 말단기를 갖는 HGM(HGM-NH2), 폴리프로필렌-말레익안하이드라이드 상용화제가 사용되었다. HGM을 포함한 복합재료는 HGM의 표면 처리에 상관없이 PP/EPDM보다 향상된 인장강도와 해수에 대해 낮은 팽윤도를 나타내었다. 같은 함량의 HGM을 포함한 경우, HGM-NH2를 포함한 복합재료가 표면처리를 하지 않은 HGM을 포함한 복합재료에 비해 보다 향상된 인장강도와 낮은 팽윤도를 나타내었다. 장시간 해수 함침 후 인장강도를 측정한 결과 복합재료의 물성 변화가 거의 없이 최초의 인장강도를 유지하였다. To be used as an encapsulant in undersea sonar devices, a material exhibiting excellent mechanical strength and a lower swelling ratio for seawater and oil is required to prolong its application. Polypropylene(PP)/ethylene-propylene-diene (EPDM) composites containing hollow glass microsphere (HGM) particles were examined to be used as an outer layer of a bilayer sonar encapsulant. To produce composites having enhanced properties, HGM particles grafted with 3-aminopropyltriethoxysilane having amine end groups (HGM-NH2) and polypropylene-maleic anhydride as a compatibilizer were used. The composite containing HGM particles exhibited better tensile strength and lower swelling ratios in the seawater than PP/EPDM blends regardless of the surface treatment of the HGM particles. At a fixed HGM content in the composite, the composite containing HGM-NH2 exhibited better tensile strength and lower swelling ratio than the composite containing untreated HGM. The tensile strengths of the composites examined here were not changed after impregnated with seawater.

Low Swelling Poly(ester) Urethane Composite Containing Modified Hollow Glass Microspheres for Seawater-Resistant Encapsulant

허유선,김주헌,임현구,윤성진 한국고분자학회 2012 Macromolecular Research Vol.20 No.12

A novel poly(ester) urethane system filled with poly(ester) urethane grafted with hollow glass microspheres was fabricated via a melt mixing method for use as an underwater encapsulant. The poly(ester) urethane/poly(ester) urethane grafted with hollow glass microsphere (HGM) composites (PU/PU-g-HGM composites) were prepared using various PU-g-HGM contents. Studies of these composites showed that the swelling ratio of PU/PUg-HGM composites in seawater and paraffin oil decreased with increasing HGM content of grafted poly(ester) urethane,while the tensile strength of PU/PU-g-HGM composites could be incrementally increased by rising PU-g-HGM content. This finding is due to the enhanced interfacial adhesion between poly(ester) urethane and poly(ester)urethane-grafted HGM due to good compatibility between these components. The tensile strength of the PU/PU-g-HGM composites in seawater (or paraffin oil) also exhibited higher levels than those of poly(ester) urethane and PU/pristine HGMs composites in seawater (or paraffin oil) as the immersion time increased. Therefore, the PU/PU-g-HGM composites were expected to have potential applications as underwater encapsulants.