Study on Packaging Method Using Silicon Substrate With Cavity and TSV for Light Emitting Diodes

Lim

ECS J. Solid State Sci. Technol.

et al. 2019

We investigated the effect of via-holes in the lead-frame on the reliability of blue flip-chip light-emitting diodes (FCLEDs). For bonding, conventional Sn-Ag(3.0%)-Cu(0.5%) solder (SAC) and Ag sintered paste were adopted. Lateral LED, conventional FCLED (c-FCLED), and via-hole FCLED gave efficacies of 218.5, 221.6 and 225 lm/W at 30 mA. The lateral LED sample (bonding material: silicone), c-FCLED sample (SAC), via-hole-type sample (Ag sinter), and via-hole-type sample (SAC) exhibited total thermal resistance of 15.24, 10.19, 8.95, and 11.79 K/W, respectively. The humidity/temperature/H 2 S gas reliability examinations showed that unlike the via-hole-type samples, the lumen of the c-FCLED was fallen by 15.0% after exposure for 500 h. Furthermore, the c-FCLED exhibited a 19.6% higher forward voltage than the via-hole FCLED after 1,000 thermal-cycles. SEM results showed that unlike the via-hole type FCLED, the c-FCLED underwent cracking after thermal cycle of 1000 times.

Section: Methodsmentioning

confidence: 99%

Via-Hole-Type Flip-Chip Packaging to Improve the Thermal Characteristics and Reliability of Blue Light Emitting Diodes

Lim

ECS J. Solid State Sci. Technol.

et al. 2019

J. Micromech. Microeng.

“…Frequently micro-reflector cavities with tapered sidewalls are added for housing the LEDs and improve light extraction efficiency [8,9]. Through silicon vias (TSV) are added to the bottom of the cavity to re-route interconnections to the backside of the package for flip-chip attachment onto PCBs [9,10]. The use of Si has also enabled the expansion of package functionality by adding integrated components such as Zener diodes for ESD protection [11], temperature sensors for monitoring LED junction temperature [12] and photosensors to detect shifts in peak emission wavelength and colour temperature with prolonged time of operation and temperature variation [7,13].…”

Section: Journal Of Micromechanics and Microengineeringmentioning

confidence: 99%

Design and fabrication of a foldable 3D silicon based package for solid state lighting applications

Sokolovskij¹,

Liu²,

Zeijl³

et al. 2015

Miniaturization of solid state lighting (SSL) luminaires as well as reduction of packaging and assembly costs are of prime interest for the SSL lighting industry. A novel silicon based LED package for lighting applications is presented in this paper. The proposed design consists of 5 rigid Si tiles connected by flexible polyimide hinges with embedded interconnects (ICs). Electrical, optical and thermal characteristics were taken into consideration during design. The fabrication process involved polyimide (PI) application and patterning, aluminium interconnect integration in the flexible hinge, LED reflector cavity formation and metalization followed by through wafer DRIE etching for chip formation and release. A method to connect chip front to backside without TSVs was also integrated into the process. Post-fabrication wafer level assembly included LED mounting and wirebond, phosphor-based colour conversion and silicone encapsulation. The package formation was finalized by vacuum assisted wrapping around an assembly structure to form a 3D geometry, which is beneficial for omnidirectional lighting. Bending tests were performed on the flexible ICs and optical performance at different temperatures was evaluated. It is suggested that 3D packages can be expanded to platforms for miniaturized luminaire applications by combining monolithic silicon integration and system-in-package (SiP) technologies.

Semicond. Sci. Technol.

“…Light-emitting diodes (LEDs) cover several lighting purposes including displays, traffic lights, signage, mobile phones, and automotive indicators owing to their outstanding properties including longevity, low power consumption, high brightness and eco-friendly behavior and it is anticipated that LEDs will be increasingly used in general illumination applications [1][2][3][4][5][6][7][8]. It is believed that LEDs will be the light source and will benefit the whole world in the near future.…”

Section: Introductionmentioning

confidence: 99%

Research on dynamic thermal performance of high-power ThinGaN vertical light-emitting diodes with different submounts

Raypah¹,

Mahmud²,

Devarajan³

2020

Investigation of dynamic thermal performance is a key to improve the heat management of high-power (HP) vertical light-emitting diodes (VLEDs). Specifically, the thermal time constant is a crucial parameter for optimizing the design and reliability of HP LEDs. Herein, the dynamic thermal behavior of seven HP ThinGaN VLEDs with different constructions was demonstrated. The LEDs’ thermal parameters were measured through the thermal transient tester system by a forward voltage technique. A three-stage of multiexponential function model was applied to divide the transient response curve into three regions with different thermal properties. This study focused on analyzing the first region that involved the chip region (epitaxial layer, wafer bonding layer, and submount) and chip bonding layer. The submounts of the LEDs under consideration include silicon carbide (SiC), silicon (Si), sapphire (Al2O3), and germanium (Ge). The results revealed that with a qualified wafer bonding layer, the LED packages with SiC, Si, and Al2O3 submount presented the optimum thermal time constant, which was 85, 69, 75, and 81 ms, respectively.