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Mischke, Peter; Strehmel, Bernd

doi:10.1515/9783748600145

Cited by 7 publications

(14 citation statements)

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“…The minimal viscosity of the powder coating melt decreases with increasing application temperature, before it finally increases again due to the onset of the crosslinking reaction. [ 20 ] This reduction of the minimum melt viscosity with increasing temperature facilitates the formation of surface irregularities.…”

Section: Resultsmentioning

confidence: 99%

“…[16,19] Besides the coalescence, the elevated temperature further causes surface leveling, degassing, and curing of powder coating (Figure 1c, III). [20,21] After powder application and curing, the next powder coating layer is applied directly on top of the previously applied powder coating. The surface temperature of the established coating can be adjusted to influence the adhesion of the powder particles of the subsequent powder coating layer, providing an additional process parameter that needs to be optimized to obtain homogeneous coatings.…”

Section: Methodsmentioning

confidence: 99%

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Electrostatic Powder Coating as a Novel Process for High‐Voltage Insulation Applications

2023

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A novel strategy for manufacturing of the main insulation of high‐voltage rotating machines is presented. The developed process is based on established electrostatic powder coating equipment. Using complete automation enables the precise and reproducible application of homogeneous powder coating layers. Individual layers can be stacked by process repetitions to achieve a desired layer thickness. This coating strategy alters the particle deposition process by introducing additional capillary bridges that significantly increase powder adhesion. A systematic parameter study is performed to provide process–structure relations connecting various process parameters with the resultant coating thickness and homogeneity. The parameters of the developed coating process are iteratively improved to maximize coating homogeneity and minimize defect density, the most critical parameters in high‐voltage insulation applications. The obtained powder coatings with a target thickness of 1.5 mm are subjected to electrical testing to examine the partial discharge activity as a key criterion for a functional insulating coating. The measurements reveal no significant partial discharge activity up to an electric field strength of 10 kV mm−1, demonstrating that this novel strategy for the production of the main insulation of high‐voltage rotating equipment surpasses the state‐of‐the‐art process in terms of partial discharge activity.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Electrostatic Powder Coating as a Novel Process for High‐Voltage Insulation Applications

2023

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“…Diese aerobe Strategie wird in großem Umfang bei Acrylaten angewendet. Die Sauerstofftoleranz dieses Systems scheint von großem Vorteil für praktische Anwendungen zu sein, insbesondere für die chemische Verfestigung von Überzügen, [229] welches ein unbequemes Spülen mit CO 2 als Inertgas erfordert, würden diese Systeme von Nutzen sein. [62,66,68] Die Fähigkeit von Kohlenstoffnitriden zur Generierung von reaktiven Sauerstoffspezies (ROS) wurde auch für die Photopolymerisation in Emulsionspolymerisationssystemen in einer von einem oberflächenaktiven Stoff freien Umgebung eingesetzt.…”

Section: Photopolymerisationen Induziert Durch Kohlenstoffnanomateria...unclassified

Lichtinduzierte Polymerisation katalysiert durch Kohlenstoff‐Nanomaterialien

Luo,

Zhai,

Wang

et al. 2024

Angewandte Chemie

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Carbon nanomaterials, specifically carbon dots and carbon nitrides, play a crucial role as heterogeneous photoinitiators in both radical and cationic polymerization processes. These recently introduced materials offer promising solutions to the limitations of current homogeneous systems, presenting a novel approach to photopolymerization. This review highlights the preparation and photocatalytic performance of these nanomaterials, emphasizing their application in various polymerization techniques, including photoinduced i) free radical, ii) RAFT, iii) ATRP, and iv) cationic photopolymerization. Additionally, it discusses their potential in addressing contemporary challenges and explores prospects in this field. Moreover, carbon nitrides, in particular, exhibit exceptional oxygen tolerance, underscoring their significance in radical polymerization processes and allowing their applications such as 3D printing, surface modification of coatings, and hydrogel engineering.

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“…A comparison of the resist thickness before and after the softbake is shown in the diagrams in figure 3. The values in figure 3 [20,21]; therefore, the resist thickness is thinner at the topography edge. Additionally, the thickness is greater on the sidewall.…”

Section: Edge Coverage and Thickness Homogeneity Over The Cavitymentioning

confidence: 99%

“…The challenge for photoresist homogeneity over topography is the homogeneous resist covering the top edge of the cavity in particular. The photoresist reflows from this top edge into the cavity due to surface tension, decreasing the photoresist thickness on the topography edge [20,21].…”

Section: Introductionmentioning

confidence: 99%

Spray-coatable negative photoresist for high topography MEMS applications

Arnold

Voigt

Haas

et al. 2017

J. Micromech. Microeng.

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In microsystem technology, the lithographical processing of substrates with a topography is very important. Interconnecting lines, which are routed over sloped topography sidewalls from the top of the protecting wafer to the contact pads of the device wafer, are one example of patterning over a topography. For structuring such circuit paths, a photolithography process, and therefore a process for homogeneous photoresist coating, is required. The most flexible and advantageous way of depositing a homogeneous photoresist film over structures with high topography steps is spray-coating. As a pattern transfer process for circuit paths in cavities, the lift-off process is widely used. A negative resist, like ma-N (MRT) or AZnLOF (AZ) is favoured for lift-off processes due to the existing negative angle of the sidewalls. Only a few sprayable negative photoresists are commercially available. In this paper, the development of a novel negative resist spray-coating based on a commercially available single-layer lift-off resist for spin-coating, especially for the patterning of structures inside the cavity and on the cavity wall, is presented. A variety of parameters influences the spray-coating process, and therefore the patterning results. Besides the spray-coating tool and the parameters, the composition of the resist solution itself also influences the coating results. For homogeneous resist coverage over the topography of the substrate, different solvent combinations for diluting the resist solution, different chuck temperatures during the coating process, and also the softbake conditions, are all investigated. The solvent formulations and the process conditions are optimized with respect to the homogeneity of the resist coverage on the top edge of the cavities. Finally, the developed spray-coating process, the resist material and the process stability are demonstrated by the following applications: (i) lift-off, (ii) electroplating, (iii) the wet and (iv) the dry chemical etching of metals on substrates with topographies.

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Cited by 7 publications

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Electrostatic Powder Coating as a Novel Process for High‐Voltage Insulation Applications

Electrostatic Powder Coating as a Novel Process for High‐Voltage Insulation Applications

Lichtinduzierte Polymerisation katalysiert durch Kohlenstoff‐Nanomaterialien

Spray-coatable negative photoresist for high topography MEMS applications

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