Cho-Hee Park

Fabrication of optically clear acrylic pressure–sensitive adhesive by photo-polymerization: UV-curing behavior, adhesion performance, and optical properties

Acrylic pressure–sensitive adhesives (PSAs) with 2-phenoxy ethyl acrylate (PEA) were polymerized using UV-curing technology. This study examined the effects of PEA content and UV dose. The photo-polymerization behavior of the pre-polymer was examined by viscosity measurements, real-time Fourier transform infrared spectroscopy, and photo-differential scanning calorimetry. The curing behaviors of the acrylic PSAs were investigated by shrinkage test, a modular advanced rheometer system, and gel content. differential scanning calorimetry and Advanced Rheometric Expansion System were used to characterize the acrylic PSAs. Adhesion performances were measured by probe tack, peel strength, and shear adhesion failure temperature. The optical properties of acrylic PSAs were examined by UV–visible spectroscopy and prism coupler. The PEA content had a larger effect on improving the optical properties, than did the UV dose. The transmittances of the acrylic PSAs with <75% PEA were >95%. The refractive indices of the acrylic PSAs increased with increasing PEA content, due to its high refractive index, >1.5, which affected the overall refractive indices, particularly in the visible region.

Synthesis and characterization of thermally stable acrylic PSA using silicone urethane methacrylate with a semi-IPN structure

To improve the thermal properties of acrylic PSA, silicone urethane methacrylate (SiUMA) is applied to acrylic PSA using a semi-interpenetrating polymer network (IPN) structure. Acrylic PSA was prepared by free radical polymerization and SiUMA was synthesized by additional polymerization via urethane linkage. By preparing synthetic SiUMA formed in a semi-IPN structure in acrylic PSA, the thermal stability can be verified with the shear adhesion failure temperature using 1u2009kg plumb weight. Normally, acrylic PSA can easily be cleared from the substrate at less than 50° C; but when using SiUMA at 10%, it can be resistant up to 100u2009C. When measuring the photo-DSC value, a 5.0u2009phr photoinitiator and UV intensity of 1000u2009mJ/cm2 can be used to complete the curing reaction. Two types of chain polymers – short and long chain polymers – were synthesized, and the structure was confirmed through FT-IR and gel permeation chromatography. By measuring the Thermogravimetric analyses, the cross-linking effect and improvement of the thermal resistance can be checked using silicone materials. With advanced rheometric expansion system, the thermal property changes and viscoelastic changes were detected. In this study, the mobility of silicone is detected while moving onto an air interface. The result of this study can provide information with which to improve the thermal stability when using SiUMA with a semi-IPN structure and acrylic PSA.

Curing Behaviors of UV-Curable Temporary Adhesives for a 3D Multichip Package Process

Temporary bonding adhesives for a three-dimensional (3D) multichip package process have been synthesized. To enhance the thermal stability, the adhesives used a fluorinated silicon urethane acrylic binder and ultraviolet (UV) curing for crosslinked network structures. Focusing on different photoinitiator contents and UV doses, the UV-curing behaviors and thermal stability were studied using Fourier-transform infrared spectroscopy attenuated total reflectance, gel fraction, swelling ratio, shrinkage, and thermogravimetric analyses.

Kinetic and characterization of UV-curable silicone urethane methacrylate in semi-IPN-structured acrylic PSAs

To improve the thermal stability of general acrylic pressure-sensitive adhesives (PSAs), polydimethylsiloxane (PDMS) was used and UV curing was employed. Silicone urethane methacrylate (SiUMA) was synthesized and introduced into acrylic PSAs for a semi-interpenetrating polymer network structure. The structure of the SiUMA was investigated through C NMR, H NMR, and FT-IR. The kinetics and behaviors of SiUMA (S1) were found by adding photoinitiators (PI) of 0.5, 1.0, 5.0, and 10u2009phr in a binder, which were examined using the photo-DSC (pDSC). After setting PI as 5.0u2009phr in a binder and UV intensity as 1000u2009mJ/cm2, the SiUMA, which was prepared by a radical polymerization, was added to acrylic PSA to 20, 40, 60, and 80% composition, and its kinetics and behaviors were analyzed by pDSC. Finally, the peel strength was checked to evaluate adhesion performance of the acrylic PSAs. The reaction rate was increased with increasing amounts of S1 and PI. Peel strength was dropped sharply with increasing crosslinking density.

Optical properties and adhesion performance of acrylic PSAs; influence of functionalized monomer and curing agent

Acrylic pressure–sensitive adhesives (PSAs) were synthesized by solution polymerization using zirconium carboxyethyl acrylate (ZrCEA) with methyl aziridine derivatives (MAZ) as a curing agent. The acrylic PSAs were characterized by Fourier transform-infrared spectroscopy and gel contents. The viscoelastic properties of the acrylic PSAs were determined using an advanced rheometric expansion system. The adhesion performance of the acrylic PSAs was determined by measuring the probe tack, peel strength, shear adhesion failure temperature, and holding power. The optical properties of the acrylic PSAs were evaluated by the transmittance and refractive index. The results show that the adhesion performance and optical properties of the acrylic PSAs are influenced by the ZrCEA and MAZ content.

Properties and Curing Behaviors of UV Curable Adhesives with Different Coating Thickness in Temporary Bonding and Debonding Process

UV curable adhesives with different acrylic functionalities were synthesized for temporary bonding and debonding process in 3D multi-chip packaging process. The aim is to study various factors which have an influence on UV curing. The properties and curing behaviors were investigated by gel fraction, peel strength, probe tack, and shear adhesion failure temperature. The results show that the properties and curing behaviors are dependent on not only acrylic functionalities of binders but also UV doses and coating thickness.