Low‐energy electron beam‐induced cationic polymerization with onium salts

Boey, Freddy; Chia, N. K.; Rath, Santosh Kumar; Abadie, M. J. M.

doi:10.1002/app.2166

Cited by 20 publications

(5 citation statements)

References 21 publications

(12 reference statements)

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“…However, thermally cured epoxy systems invariably suffer from relatively long cure times and, for high‐temperature systems, an unacceptably high curing temperature may actually damage the components and devices, which are expected to be protected. Attempts to cure epoxy systems, formulated with photoinitiators, by UV or e‐beam radiation3–8 have shown several advantages over the thermal process, with the most important being the reduction by at least an order of magnitude in cure time, as well as the minimization of residual stress. This paper reports on the use of a low‐energy e‐beam radiation process to cure the epoxy system SU8 and, subsequent characterization of the degree of conversion by using Fourier‐transform infrared (FTIR) spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Cationic electron‐beam curing of a high‐functionality epoxy: effect of post‐curing on glass transition and conversion

Rath¹,

Boey²,

Abadie³

2004

Polymer International

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This paper reports on the cationic electron‐beam curing of a high‐functionality SU8 epoxy resin, which is extensively used as a UV‐curing negative photoresist for micro‐electronics machine systems (MEMS) applications. Results show that elevated post‐curing treatment significantly increased both the conversion and the glass transition. The degree of conversion and the glass transition temperature were measured by using Fourier‐transform infrared (FTIR) spectroscopy and modulated differential scanning calorimetry (MDSC®), respectively. The glass transition temperature (Tg), which has been observed to be dependent on the degree of conversion, reaches a maximum of 162 °C at 50 Mrad and post‐curing at 90 °C. The degradation pattern of the cured resin does not show much variation for exposure at 5 Mrad, but does show significant variation for 50 Mrad exposure at various post‐curing temperatures. A degree of conversion of more than 0.8 was achieved at a dosage of 30 Mrad with post curing at 80 °C, for the epoxy resin with an average functionality of 8 a feature simply not achievable when using UV‐curing. Copyright © 2004 Society of Chemical Industry

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Section: Introductionmentioning

confidence: 99%

Cationic electron‐beam curing of a high‐functionality epoxy: effect of post‐curing on glass transition and conversion

Rath¹,

Boey²,

Abadie³

2004

Polymer International

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“…Both, the direct activation of epoxy groups as well as the dissociation of the sulfonium salt contribute to a cross linking of SU8 exposed to electron irradiation. The resulting polymer differs from its UVA-crosslinked counterpart in several material properties such as the glass transition temperature and the level of mechanical stress [34,35]. The latter combined with the observations that SU8-LIPSS is highly susceptible to both, bending of the wafer substrate as well as touching with an AFM tip, led to the conclusion that mechanical stress is the key factor for the deletion of the periodic pattern.…”

Section: Resultsmentioning

confidence: 99%

Mechanically metastable structures generated by single pulse laser-induced periodic surface structures (LIPSS) in the photoresist SU8

Reinhardt

Peschke²,

Riedel³

et al. 2018

Nanotechnology

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Laser-induced periodic surface structures (LIPSS) with a periodicity of 351 nm are generated in the negative photoresist SU8 by single nanosecond laser pulse impact. Friction scans indicate the periodic pattern to comprise alternating regions of crosslinked and non-crosslinked SU8. Intriguingly, even minor mechanical stimuli in the order of nanonewtons cause the unfolding or rather the deletion of the characteristic periodic pattern similarly to the release of a pre-loaded spring. This feature combined with high resilience to heat and photon irradiation makes SU8-LIPSS attractive for applications such as mechanical stress monitors, self-destructing memory and passive micro actuators.

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“…Photochemically induced cationic polymerization has been shown to be applicable to the high functionality epoxy-based negative photoresist material -SU8, which has been widely used in photolithographic fabrication of micro-electromechanical systems (MEMS) [19,20].…”

Section: Results Obtained and Discussionmentioning

confidence: 99%

UV curing kinetic of high performance epoxy resin for Roll-to-Roll UV embossing

Voytekunas

Shan

et al. 2010

2010 12th Electronics Packaging Technology Conference

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In present work curing kinetics of UV-initiated cationic photo-polymerization of EPICLON series epoxy resin HP-820 and key cure process parameters, such as the extent of crosslinking and conversion, polymerization rate and the order of reactions have been studied by Photo-Differential Scanning Calorimetry (DPC). Different kinetics analysis results, including enthalpy of the reaction, induction time, peak maximum, percentage conversion were obtained for studied epoxy system at different isothermal temperatures (30-70 o C), allowing calculating activation energy. Two kinetic parameters -coefficient rate (k) and the order of the initiating reaction (m) were determined, using an autocatalytic kinetics model. IntroductionThe extensive development of the UV curing technology has opened the way to numerous end uses, more recently -in nonconventional micro-patterning technique -in a continuous Roll-to-Roll (R2R) UV embossing, which can provide a solution for high speed large area nano-and microscale patterning of different structures with greatly improved throughput [1-6]. One of the examples is microlens array (MLA) film, which among various application found in the field of optical sensors and communications, displays, lighting devices etc can be an effective solution in enhancing the light and increasing optical coupling efficiency [7].Among polymer-based lens materials having been extensively studied since 1990s, UV curable has been shown to be the most attractive not only from environmental point of view, introducing solvent free formulations and ambient temperature operations but also due to the high polymerization speed of resins, resulting in reduced cost of final product [2]. Tailor made properties -is another great advantage of materials, produced by UV induced polymerization [3].The market of photocurable resins is very large and diversified. Among two major classes of UV-curable resins available on the market and often used in various UV-assisted patterning processes and techniques -multifunctional acrylates, and multifunctional epoxides, the last ones present number of advantages. First of all, epoxies are cured via cationic, oxygen inhibition free curing mechanism, allowing avoiding special environmental conditions needed for acrylates, cured via radical mechanism [8]. More of that, its lower, compare, to acrylate resins shrinkage after curing allows more faithful pattern application. However, despite these advantages their market is still small, and one of the reason, beside the price is probably related to their lower than acrylate`s and methacrylate`s reactivity.

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Low‐energy electron beam‐induced cationic polymerization with onium salts

Cited by 20 publications

References 21 publications

Cationic electron‐beam curing of a high‐functionality epoxy: effect of post‐curing on glass transition and conversion

Cationic electron‐beam curing of a high‐functionality epoxy: effect of post‐curing on glass transition and conversion

Mechanically metastable structures generated by single pulse laser-induced periodic surface structures (LIPSS) in the photoresist SU8

UV curing kinetic of high performance epoxy resin for Roll-to-Roll UV embossing

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