Injection molding micro patterns with high aspect ratio using a polymeric flexible stamper

Park, S. W.; Lee, W. I.; Moon, Sung Nam; Yoo, Yeong-Eun; Cho, Y. H.

doi:10.3144/expresspolymlett.2011.93

Cited by 32 publications

(29 citation statements)

References 16 publications

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“…As expected, it is widely found that higher holding pressure improves replication . Where this is not so, the reason may be the pre‐existence of a thick frozen layer resisting deformation.…”

Section: Replication Of Micro‐features In Injection Moldingsupporting

confidence: 53%

Replication of surface micro‐features using variothermal injection molding: Application to micro‐fluidics

Pittman¹,

Wlodarski²

2017

Polymer Engineering & Sci

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We study injection molding of mesoscale items with µm‐scale surface features, namely micro‐fluidic channels, relating replication quality to process conditions. Using variothermal molding, the variables are the pre‐heat temperature of the cavity insert surface before melt injection and the mold cooling start time. Surface temperatures and in‐cavity melt pressures are continuously measured. Rounded upper corners of the micro‐channels are used as an index of replication quality. For polymethylmethacrylate the thickness of a layer with solid‐like properties (below 124°C) is calculated and used with pressures to interpret results. It is shown how improved replication correlates with low layer thickness at the end of the compression phase when pressures are at a maximum, and the necessity of properly timed cooling to lock in replication before melt pressures fall. Results show how the inter‐relationship of layer thickness and melt pressure is controlled by pre‐heat temperature and cooling switch‐on time. Delayed cooling can result in poorer replication, due to a retraction effect of the plastic. Too early cooling also reduces replication of parallel‐to‐flow features downstream of transverse features, and of the replication of transverse features on their downstream side. Good replication of 100 and 70 µm channels requires lower pre‐heat than 400 µm ones. POLYM. ENG. SCI., 58:1726–1738, 2018. © 2017 Society of Plastics Engineers

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Section: Replication Of Micro‐features In Injection Moldingsupporting

confidence: 53%

Replication of surface micro‐features using variothermal injection molding: Application to micro‐fluidics

Pittman¹,

Wlodarski²

2017

Polymer Engineering & Sci

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“…Injection molding using a Ni mold with the same surface pattern resulted in replicated pillars with only about 30% of the nominal height. Another study demonstrated replication of 1 µm wide polymer gratings with an aspect ratio of 9 using a patterned polyurethane acrylate (PUA) layer on a 40 µm thick polyethylene terephthalate (PET) film, although the replication quality was not uniform [38].…”

Section: Discussionmentioning

confidence: 99%

“…Likewise, a polymer foil covering one of the mold halves allowed fabrication of high-aspect ratio microcantilevers through an isothermal process [37]. Furthermore, polymeric stampers with imprinted micro- [38] and nano-structures [39] showed improved filling at low mold temperatures compared to a nickel stamper. Although these examples demonstrated impressive replication without the need for a variotherm process, they are likely not suitable for highvolume production as the mold materials used lack the mechanical durability that is required in an industrial setting.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen silsesquioxane mold coatings for improved replication of nanopatterns by injection molding

Hobæk

Matschuk²,

Kafka³

et al. 2015

J. Micromech. Microeng.

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We demonstrate the replication of nanosized pillars in polymer (cyclic olefin copolymer) by injection molding using nanostructured thermally cured hydrogen silsesquioxane (HSQ) ceramic coatings on stainless steel mold inserts with mold nanostructures produced by a simple embossing process. At isothermal mold conditions, the average pillar height increases by up to 100% and a more uniform height distribution is observed compared to a traditional metal mold insert. Thermal heat transfer simulations predict that the HSQ film retards the cooling of the polymer melt during the initial stages of replication, thus allowing more time to fill the nanoscale cavities compared to standard metal molds. A monolayer of a fluorinated silane (heptadecafluorotrichlorosilane) deposited on the mold surface reduces the mold/polymer interfacial energy to support demolding of the polymer replica. The mechanical stability of thermally cured HSQ makes it a promising material for nanopattern replication on an industrial scale without the need for slow and energy intensive variotherm processes.

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“…Especially imprinting with negative polydimethylsiloxane (PDMS) molds and ultraviolet (UV) curable materials, soft embossing has emerged as a novel technology for polymer micro-structures fabrication [16]- [18]. Compared with other micro-structure fabrication technologies including the injection molding [19], diamond tooling [20], hot embossing [21], and laser processing [22], soft embossing is simple and highly efficient. It neither requires high temperatures nor a heavy press, leading to large areas of microoptical structures without birefringence or thermal damage.…”

Section: Introductionmentioning

confidence: 99%

Electrically Controllable Liquid Crystal Component for Efficient Light Steering

et al. 2015

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In this paper, we present an electrically controllable microoptical component for light beam steering and light intensity distribution built on the combination of nematic liquid crystal (LC) and polymer microprisms. Polymer microprism arrays are fabricated using soft embossing with elastic polydimethylsiloxane molds and ultraviolet curable resins. Surface profiling measurements show that the dimensions of the replicated prisms closely approximate those of the master prism. Two different LC alignment techniques were employed: hybrid rubbing alignment and obliquely evaporated SiO 2 alignment, both of which result in proper alignment of the LC molecules along the prism groove direction. The operation voltage of the LC components is relatively low (10 V rms ). The steering angle of a green laser beam was experimentally studied as a function of applied voltage, and a steering range of 3 was found. The active LC components also effectively deflect a collimated white light beam over a steering angle of about 2 with an efficiency of 27%-33%. All the optical measurements are in agreement with theoretical calculations based on Snell's law.

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Injection molding micro patterns with high aspect ratio using a polymeric flexible stamper

Cited by 32 publications

References 16 publications

Replication of surface micro‐features using variothermal injection molding: Application to micro‐fluidics

Replication of surface micro‐features using variothermal injection molding: Application to micro‐fluidics

Hydrogen silsesquioxane mold coatings for improved replication of nanopatterns by injection molding

Electrically Controllable Liquid Crystal Component for Efficient Light Steering

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