An Optimal Cure Process to Minimize Residual Void and Optical Birefringence for a LED Silicone Encapsulant

Abstract

Silicone resin has recently attracted great attention as a high-power Light Emitting Diode (LED) encapsulant material due to its good thermal stability and optical properties. In general, the abrupt curing reaction of the silicone resin for the LED encapsulant during the curing process induces reduction in the mechanical and optical properties of the LED product due to the generation of residual void and moisture, birefringence, and residual stress in the final formation. In order to prevent such an abrupt curing reaction, the reduction of residual void and birefringence of the silicone resin was observed through experimentation by introducing the multi-step cure processes, while the residual stress was calculated by conducting finite element analysis that coupled the heat of cure reaction and cure shrinkage. The results of experiment and analysis showed that it was during the three-step curing process that the residual void, birefringence, and residual stress reduced the most in similar tendency. Through such experimentation and finite element analysis, the study was able to confirm that the optimization of the LED encapsulant packaging process was possible.

Simulation-Based Optimization of Cure Cycle of Large Area Compression Molding for LED Silicone Lens

“…Changes according to Dwell Temperature ( 2 ). First of all, the changes according to dwell temperature ( 2 ) were investigated because Song et al [2] reported that one-step dwell temperature affected most of the changes. 2 was set to 103 ∘ C, 113 ∘ C, and 123 ∘ C. One-step heating rate ( 1 ) was set to 30 ∘ C/min, while two-step heating rate ( 2 ) was set to 10 ∘ C/min.…”

“…Silicone resin is manufactured through a process in which liquid-phase base and curing agent are mixed and input into mold and then cured by heat followed by cooling. However, abrupt temperature increase in the resin by excessive chemical reaction during curing leads to surface roughening, delamination from LED chip, residual void and moisture, and residual stress, resulting in the impairment of the mechanical and optical properties of LED product [2]. Therefore, a numerical simulation is tried to forecast abrupt temperature increases during the curing process and it has been applied as a means of optimal cure cycle [3][4][5].…”

“…In the earlier studies, residual stress was simulated in the cure process for the silicone resin of simple cylindrical LED encapsulation [2]. In this study, three-dimensional heat transfer-cure simulation was performed for the large area compression molding process to simultaneously form silicone resin lenses and encapsulants for LED.…”

Synthesis of phenyl silicone resin with epoxy and acrylate group and its adhesion enhancement for addition-cure silicone encapsulant with high refractive index

“…In recent years, light emitting diode (LED) has gradually taken the place of incandescent, fluorescent, and neon lamp owing to its many attractive properties such as high luminous efficiency, driving at low voltage, high resistance to vibration, low power consumption, superior lifetime, light weight, [1][2][3][4] and is widely used in lighting and display fields. The encapsulant is an important component of LED devices.…”

RGB-Stack Light Emitting Diode Modules with Transparent Glass Circuit Board and Oil Encapsulation

“…The efficiency of LED products in basic terms is the ratio of light output to the space outside the device and power input to the device, in other words, emitted flux (lumens) divided by power draw (watts). However, there are still several important issues, such as LED packages, thermal handling properties, and optical loss, which affect the total quality of LED devices [ 2 , 3 , 4 , 5 , 6 , 7 ]. Of course, LED package efficiency also has many variables, such as the method of generating white light, color quality, and drive methodology.…”