Characterizing nanoimprint profile shape and polymer flow behavior using visible light angular scatterometry

2007 ◽  
Vol 25 (6) ◽  
pp. 2396 ◽  
Author(s):  
Rayan M. Al-Assaad ◽  
Suresh Regonda ◽  
Li Tao ◽  
Stella W. Pang ◽  
Wenchuang (Walter) Hu
Keyword(s):  
Visible Light ◽  
Flow Behavior ◽  
Polymer Flow ◽  
Profile Shape

Finite Element Modeling of Polymer Flow during Hot Embossing with Different Mold Structures and Embossing Conditions

2011 ◽  
Vol 305 ◽  
pp. 144-148 ◽  
Author(s):  
Ting Zhang ◽  
Yong He ◽  
Jian Zhong Fu
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Simulation Study ◽  
Flow Behavior ◽  
Hot Embossing ◽  
Duty Ratio ◽  
Squeezing Flow ◽  
Polymer Flow ◽  
Common Substrate ◽  
Present Simulation

The geometric structures of the mold and embossing conditions can obviously influence the filling flows in the polymeric patterns. In this study, embossing stamp and substrate with different geometries are used to investigate the flow behavior under both isothermal and non-isothermal conditions. In general, for the stamp, small duty ratio cavity fills more sufficiently than large duty ratio cavity. With the same cavity duty ratio, inner cavity fills more quickly and sufficient than outer cavity. Compared to multiple cavities stamp, individual cavity fills more slowly, especially embossed with the stamp having small duty ratio cavity. Under non-isothermal embossing, the filling flow indicates a wall climbing flow and the polymer flow replaces the outer cavity better. Uncommon substrate provides a limitation of out-squeezing flow from polymer layers, so the polymer pick reaches the mold faster than common substrate like the flat. The present simulation study provides an analysis of the mold geometry especially the substrate geometry to govern filling flow and replication fidelity.

Cavity Filling Analysis for the Fabrication of an Alignment Structure in Micro Hot Embossing

2012 ◽  
Author(s):  
J. A. Gomez ◽  
T. G. Conner ◽  
I.-H. Song ◽  
D.-H. Chun ◽  
Y.-J. Kim ◽  
...  
Keyword(s):  
Flow Behavior ◽  
Mold Insert ◽  
Hot Embossing ◽  
Polymer Flow ◽  
Finite Element Software ◽  
Complete Filling ◽  
Alignment Structure ◽  
Filling Analysis ◽  
Cavity Filling ◽  
Deform 2D

The flow behavior of polymers was analyzed using a commercial finite element software, DEFORM-2D, for the replication of microstructures. An alignment structure for microassembly, a hemisphere-tipped post, was modeled to demonstrate the polymer flow in hot embossing. The mold filling with polymer was evaluated by the heights of molded posts. The results of simulation showed better replication fidelity of the post with the increase of the molding temperature and displacement of the mold insert. The complete filling of a mold cavity was achieved at the molding temperatures of 112.5, 125, 137.5, and 150°C when the displacements were 1.5, 2.0 and 2.5 mm. The model can be used to design the process parameters for the reliable replication of microstructures.

Polymer Flow Behavior from Multispeed Viscometry

1965 ◽  
Vol 38 (4) ◽  
pp. 769-781 ◽  
Author(s):  
W. E. Wolstenholme
Keyword(s):  
Activation Energy ◽  
Flow Curve ◽  
Flow Behavior ◽  
Standard Procedure ◽  
Isothermal Flow ◽  
Thermal Dependence ◽  
Flow Curves ◽  
Polymer Flow ◽  
Constant Rate ◽  
Constant Viscosity

Abstract A practical viscometric technique has been developed for measuring flow of commercial elastomeric and thermoplastic materials at processing temperatures. A standard procedure for testing bulk polymer samples in a modified shearing disk Mooney viscometer with rotor speeds from .05 to 77 rpm is described in detail. Research, development or process control personnel can rapidly convert viscometer torque dial readings at the various rotor speeds to an isothermal flow curve in absolute units of shear stress and rate of shear by either of two methods shown by examples. Total time to test a polymer sample and plot the flow curve is less than one hour. Representative flow curves illustrate how polymers with essentially equivalent ML-4 @ 212° F can have large differences in flow at processing conditions. A set of isothermal flow curves covering a desired temperature range provides an excellent estimate of processing behavior over a range of temperatures. Numerical determination of the thermal dependence of flow is easily evaluated in terms of activation energy at constant shearing stress, constant rate of shear, or constant viscosity. Activation energy is a useful constant for characterization of non-Newtonian polymer flow.

Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

1992 ◽  
Vol 50 (2) ◽  
pp. 1038-1039
Author(s):  
Shawn Williams ◽  
Xiaodong Zhang ◽  
Susan Lamm ◽  
Jack Van’t Hof
Keyword(s):  
Visible Light ◽  
Radiation Damage ◽  
Cross Section ◽  
Imaging Techniques ◽  
Dose Range ◽  
Specimen Preparation ◽  
X Rays ◽  
Metaphase Chromosomes ◽  
X Ray ◽  
Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

1994 ◽  
Vol 52 ◽  
pp. 74-75
Author(s):  
C. Jacobsen ◽  
J. Fu ◽  
S. Mayer ◽  
Y. Wang ◽  
S. Williams
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Light Emission ◽  
Chinese Hamster ◽  
Polystyrene Spheres ◽  
Good Resistance ◽  
X Ray ◽  
Selective Staining ◽  
Visible Light Emission ◽  
Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

Photocatalyst-free decarboxylative aminoalkylation of imidazo[1,2-a]pyridines with N-aryl glycines enabled by visible light

2019 ◽  
Vol 6 (21) ◽  
pp. 3693-3697 ◽  
Author(s):  
Jiu-Jian Ji ◽  
Zhi-Qiang Zhu ◽  
Li-Jin Xiao ◽  
Dong Guo ◽  
Xiao Zhu ◽  
...  
Keyword(s):  
Visible Light

A novel, green and efficient visible-light-promoted decarboxylative aminoalkylation reaction of imidazo[1,2-a]pyridines with N-aryl glycines has been described.

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