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Low Shrinkage (low + shrinkage)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Zero Shrinkage of LTCC by Self-Constrained Sintering

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 5 2005
Torsten Rabe
Low shrinkage in x and y direction and low tolerances of shrinkage are an indispensable precondition for high-density component configuration. Therefore, zero shrinkage sintering technologies as pressure-assisted sintering and sacrificial tapes have been introduced in the low-temperature co-fired ceramics (LTCC) production by different manufacturers. Disadvantages of these methods are high costs of sintering equipment and an additional process step to remove the sacrificial tapes. In this article, newly developed self-constrained sintering methods are presented. The new technology, HeraLock®, delivers LTCC modules with a sintering shrinkage in x and y direction of less than 0.2% and with a shrinkage tolerance of ±0.02% without sacrificial layers and external pressure. Each tape is self-constrained by integration of a layer showing no shrinkage in the sintering temperature range of the LTCC. Large area metallization, integration of channels, cavities and passive electronic components are possible without waviness and camber. Self-constrained laminates are an alternative way to produce zero shrinkage LTCC. They consist of tapes sintering at different temperature intervals. Precondition for a successful production of a self-constrained LTCC laminate is the development of well-adapted material and tapes, respectively. This task is very challenging, because sintering range, high-temperature reactivity and thermal expansion coefficient have to be matched and each tape has to fulfill specific functions in the final component, which requires the tailoring of many properties as permittivity, dielectric loss, mechanical strength, and roughness. A self-constrained laminate is introduced in this article. It consists of inner tapes sintering at especially low-temperature range between 650°C and 720°C and outer tapes with an as-fired surface suitable for thin-film processes. [source]

Low-Distortion Holographic Data Storage Media Using Free-Radical Ring-Opening Polymerization

ADVANCED FUNCTIONAL MATERIALS, Issue 22 2009
Kyongsik Choi
Abstract Holographic data storage, due to its potential to increase capacity beyond one terabyte per disk, is tipped to be one of the next generation optical data storage technologies. Polymer-based systems are leading candidates due to their high dynamic range, high sensitivities, and flexible and easy production, and yet polymerization-shrinkage-induced distortion is a major hurdle for its reliable use. In this paper, a new free radical polymerization holographic recording medium, based on low shrink cyclic allylic sulfides (LS-CASs) ring-opening monomers, is proposed and demonstrated. The percentage of volume shrinkage is measured to be 0.02%, with refractive index (RI) contrast of (1.01,±,0.5),×,10,3. The measured volume shrinkage is, to the authors' best knowledge, the best reported so far in the literature. Other parameters such as sensitivity, dynamic range, and dark reaction properties are also measured, where the values can be optimized with high RI functional groups without sacrificing the low shrinkage. [source]

Synthesis and characterization of photopatternable epoxy hybrid materials for the fabrication of thick and thermally stable microstructures with a high aspect ratio

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008
Kyung Ho Jung
Abstract Photosensitive cycloaliphatic-epoxy oligosiloxane was synthesized using a nonhydrolytic sol,gel reaction for the fabrication of thick and thermally stable microstructures with high aspect ratios. Its formation was confirmed by 29Si and 1H nuclear magnetic resonance spectroscopy, small-angle neutron scattering, and Fourier transform infrared spectroscopy. Photocuring of cycloaliphatic-epoxy oligosiloxane resin resulted in a thermally stable epoxy hybrid material (epoxy hybrimer). Micropatterns with a high aspect ratio (>5), an excellent sidewall shape, and low shrinkage were fabricated directly from these materials using a simple photolithographic process. The fabricated micropattern sustained temperatures of up to 250°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Functionalization of COC Surfaces by Microwave Plasmas

PLASMA PROCESSES AND POLYMERS, Issue S1 2007
Hartmut Steffen
Abstract Cyclic olefin copolymers (COC) combine excellent transparency, high moisture barrier, high strength and stiffness and very low shrinkage. COCs have excellent chemical resistance to aqueous acids and bases and to most polar solvents. This property combination makes them excellent candidates for diverse diagnostic applications in biomedical science. But they are very hydrophobic and thus not suitable for cell-contacting applications. This work investigates the surface functionalization of COC compared to PS by NH3 and SO2 microwave plasmas. The surfaces were mainly analysed by high-resolution X-ray photoelectron spectroscopy (XPS). Moreover, cells were cultivated on both substrates to verify the applicability of COC for cell-based disposables. Actually, microwave plasma-functionalized COC surfaces support the adhesion and proliferation of adherent cell lines, which usually require the coating of the substrate with extra cellular matrix molecules. [source]