Thermally resistant UV-curable epoxy–siloxane hybrid materials for light emitting diode (LED) encapsulation

Jang

et al. 2020

Adv Elect Materials

Reports have recently been published on ultrathin biofluid barriers, which enable the long‐term measurement of biological signals and exhibit conformability on nonlinear surfaces such as skin and organs. However, inorganic‐ and organic‐based barriers have process incompatibility and high water permeability, respectively. Siloxane‐ (inorganic) based fluorinated epoxy (organic) hybrid materials (FEH) are demonstrated for bio‐fluidic barrier and the biocompatibility and barrier performance for flexible electronic systems as solution‐processed oxide thin‐film transistors (TFTs) on 1.2 µm thick polyimide (PI) thin film substrate is confirmed. FEH thin film can be patterned as small as 10 µm through conventional photolithography. The fabricated solution‐processed indium oxide TFTs with FEH barriers exhibit durable performance over 16 h with no dramatic change of transfer characteristics in phosphate‐buffered saline (PBS) environment. Furthermore, to realize FEH barriers for flexible systems, the solution‐processed indium oxide TFTs with FEH barriers on ultrathin PI substrate are demonstrated subjected to compression test and successfully measure the electrical properties with no irreversible degradation during 1000 cycles of mechanical testing in PBS.

Section: Methodsmentioning

confidence: 99%

“…SU‐8 (MicroChem), polyimide using poly(pyromellitic dianhydride‐ co ‐4,4′‐oxydianiline), amic acid solution, Sigma‐Aldrich), and cycloaliphatic epoxy hybrimer (EH)41 film were deposited by spin coating. Parylene film was deposited by chemical vapor deposition method.…”

Section: Methodsmentioning

confidence: 99%

Solution‐Processed, Photo‐Patternable Fluorinated Sol–Gel Hybrid Materials as a Bio‐Fluidic Barrier for Flexible Electronic Systems

Lee

Jang

et al. 2020

Adv Elect Materials

“…[35][36][37][38] Numerous investigations on cycloaliphatic epoxy resin blends have been reported in the literature, [39][40][41][42][43] but very little has been extensively discussed about their structure property relationship. In this work, HBADGE with relatively lower polarity and higher flexibility was selected to blend with cycloaliphatic epoxy ECC to investigate the influence of formula change on LEDs performance.…”

Section: Introductionmentioning

confidence: 99%

Effect of Chain Flexibility of Epoxy Encapsulants on the Performance and Reliability of Light-Emitting Diodes

Chen

Liu

Shen

et al. 2016

Ind. Eng. Chem. Res.

Cycloaliphatic epoxy resin (3-4-epoxycyclohexane) methyl 3-4-epoxycyclohexylcarboxylate (ECC) was formulated with flexible hydrogenated bisphenol A diglycidyl ether (HBADGE) to inspect the influence of chain flexibility on the performance and reliability of epoxy packaged Light-emitting Diode (LED). The properties of epoxy encapsulants were characterized by using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), ultraviolet visible (UV−Vis) spectrophotometer, thermomechanical analyzer (TMA), scanning acoustic microscopy (SAM), and scanning electron microscopy (SEM). With the incorporation of flexible HBADGE, favorable properties were obtained, such as decreased thermal expansion coefficient (CTE), lowered storage modulus at reflow temperature, and depressed equilibrium water uptake for the epoxy packaging materials.The light transmittance of encapsulants differed after thermal and UV aging. Compared with Neat ECC and Neat HBADGE, the HBADGE-modified encapsulants endowed LED devices with good performance and high reliability.

“…Light‐emitting diodes (LEDs) have received much attention in the fields of lighting and display due to their high luminescent efficiency and ability to be driven at low voltage condition . Due to these properties, LEDs have been tried for a number of applications including display backlighting, bright illumination, and as parts of energy storage systems . As part of the LED packaging, an LED chip is encapsulated within a transparent material to protect the LED chip from a number of harmful aspects of the external environment (e.g., dust, humidity, and shock).…”

Section: Introductionmentioning

confidence: 99%

Low temperature curable epoxy siloxane hybrid materials for LED encapsulant

Bae

J of Applied Polymer Sci

et al. 2013

Self Cite

A thermally cured epoxy-siloxane hybrid material that is curable at low temperature (L-expoxy hybrimer) was investigated for use as an LED encapsulant. This new hybrimer was fabricated using thermally initiated, cationic polymerization of cycloaliphatic epoxy oligosiloxane (CAEO) resin, derived from non-hydrolytic sol-gel, mixed with oxetane hardener in the presence of a hexafluoroantimonate-type thermo-cationic initiator. The L-epoxy hybrimer was cured at a lower temperature (below 120 C) than previously reported for an epoxy hybrimer with anhydride hardener (above 180 C). The L-epoxy hybrimer showed high thermal resistance to yellowing under long-term high temperature condition, and maintained good optical transmittance. Also, it had a high refractive index (up to 1.57), as well as the hardness (Shore D 80), and low water-vapor permeability, when the new hybrimer was used to encapsulate an LED, it showed good adhesion without cracks or delamination and maintained their initial performance after the long-term aging tests (120 and 85 C at 85% humidity).