Browsing by Author "Guenther, Thomas"

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Open Access
Adhesion-induced demolding forces of hard coated microstructures measured with a novel injection molding tool
(2023) Schoenherr, Maximilian; Ruehl, Holger; Guenther, Thomas; Zimmermann, André; Gundelsweiler, Bernd
The demolding of plastic parts remains a challenging aspect of injection molding. Despite various experimental studies and known solutions to reduce demolding forces, there is still not a complete understanding of the effects that occur. For this reason, laboratory devices and in-process measurement injection molding tools have been developed to measure demolding forces. However, these tools are mostly used to measure either frictional forces or demolding forces for a specific part geometry. Tools that can be used to measure the adhesion components are still the exception. In this study, a novel injection molding tool based on the principle of measuring adhesion-induced tensile forces is presented. With this tool, the measurement of the demolding force is separated from the actual ejection step of the molded part. The functionality of the tool was verified by molding PET specimens at different mold temperatures, mold insert conditions and geometries. It was demonstrated that once a stable thermal state of the molding tool was achieved, the demolding force could be accurately measured with a comparatively low force variance. A built-in camera was found to be an efficient tool for monitoring the contact surface between the specimen and the mold insert. By comparing the adhesion forces of PET molded on polished uncoated, diamond-like carbon and chromium nitride (CrN) coated mold inserts, it was found that a CrN coating reduced the demolding force by 98.5% and could therefore be an efficient solution to significantly improve demolding by reducing adhesive bond strength under tensile loading.
Open Access
Analysis of tempering effects on LDS-MID and PCB substrates for HF applications
(2023) Wolf, Marius; Werum, Kai; Guenther, Thomas; Schleeh, Lisa; Eberhardt, Wolfgang; Zimmermann, André
Mechatronic Integrated Devices or Molded Interconnect Devices (MID) are three-dimensional (3D) circuit carriers. They are mainly fabricated by laser direct structuring (LDS) and subsequent electroless copper plating of an injection molded 3D substrate. Such LDS-MID are used in many applications today, especially antennas. However, in high frequency (HF) systems in 5G and radar applications, the demand on 3D circuit carriers and antennas increases. Electroless copper, widely used in MID, has significantly lower electrical conductivity compared to pure copper. Its lower conductivity increases electrical loss, especially at higher frequencies, where signal budget is critical. Heat treatment of electroless copper deposits can improve their conductivity and adhesion to the 3D substrates. This paper investigates the effects induced by tempering processes on the metallization of LDS-MID substrates. As a reference, HF Printed Circuit Boards (PCB) substrates are also considered. Adhesion strength and conductivity measurements, as well as permittivity and loss angle measurements up to 1 GHz, were carried out before and after tempering processes. The main influencing factors on the tempering results were found to be tempering temperature, atmosphere, and time. Process parameters like the heating rate or applied surface finishes had only a minor impact on the results. It was found that tempering LDS-MID substrates can improve the copper adhesion and lower their electrical resistance significantly, especially for plastics with a high melting temperature. Both improvements could improve the reliability of LDS-MID, especially in high frequency applications. Firstly, because increased copper adhesion can prevent delamination and, secondly, because the lowered electrical resistance indicates, in accordance with the available literature, a more ductile copper metallization and thus a lower risk of microcracks.
Open Access
Characterization and benchmark of a novel capacitive and fluidic inclination sensor
(2021) Schwenck, Adrian; Guenther, Thomas; Zimmermann, André
In this paper, a fluidic capacitive inclination sensor is presented and compared to three types of silicon-based microelectromechanical system (MEMS) accelerometers. MEMS accelerometers are commonly used for tilt measurement. They can only be manufactured by large companies with clean-room technology due to the high requirements during assembly. In contrast, the fluidic sensor can be produced by small- and medium-sized enterprises (SMEs) as well, since only surface mount technologies (SMT) are required. Three different variants of the fluidic sensor were investigated. Two variants using stacked printed circuit boards (PCBs) and one variant with 3D-molded interconnect devices (MIDs) to form the sensor element are presented. Allan deviation, non-repeatability, hysteresis, and offset temperature stability were measured to compare the sensors. Within the fluidic sensors, the PCB variant with two sensor cavities performed best regarding all the measurement results except non-repeatability. Regarding bias stability, white noise, which was determined from the Allan deviation, and hysteresis, the fluidic sensors outperformed the MEMS-based sensors. The accelerometer Analog Devices ADXL355 offers slightly better results regarding offset temperature stability and non-repeatability. The MEMS sensors Bosch BMA280 and TDK InvenSense MPU6500 do not match the performance of fluidic sensors in any category. Their advantages are the favorable price and the smaller package. From the investigations, it can be concluded that the fluidic sensor is competitive in the targeted price range, especially for applications with extended requirements regarding bias stability, noise, and hysteresis.
Open Access
Characterization of a PCB based pressure sensor and its joining methods for the metal membrane
(2021) Schwenck, Adrian; Grözinger, Tobias; Guenther, Thomas; Schumacher, Axel; Schuhmacher, Dietmar; Werum, Kai; Zimmermann, André
The collection and analysis of industrial Internet of Things (IIoT) data offer numerous opportunities for value creation, particularly in manufacturing industries. For small and medium-sized enterprises (SMEs), many of those opportunities are inaccessible without cooperation across enterprise borders and the sharing of data, personnel, finances, and IT resources. In this study, we suggest so-called data cooperatives as a novel approach to such settings. A data cooperative is understood as a legal unit owned by an ecosystem of cooperating SMEs and founded for supporting the members of the cooperative. In a series of 22 interviews, we developed a concept for cooperative IIoT ecosystems that we evaluated in four workshops, and we are currently implementing an IIoT ecosystem for the coolant management of a manufacturing environment. We discuss our findings and compare our approach with alternatives and its suitability for the manufacturing domain.
Open Access
Characterization of hermetically sealed metallic feedthroughs through injection-molded epoxy-molding compounds
(2021) Haybat, Mehmet; Guenther, Thomas; Kulkarni, Romit; Sahakalkan, Serhat; Grözinger, Tobias; Rothermel, Thilo; Weser, Sascha; Zimmermann, André
Electronic devices and their associated sensors are exposed to increasing mechanical, thermal and chemical stress in modern applications. In many areas of application, the electronics are completely encapsulated with thermosets in a single process step using injection molding technology, especially with epoxy molding compounds (EMC). The implementation of the connection of complete systems for electrical access through a thermoset encapsulation is of particular importance. In practice, metal pin contacts are used for this purpose, which are encapsulated together with the complete system in a single injection molding process step. However, this procedure contains challenges because the interface between the metallic pins and the plastic represents a weak point for reliability. In order to investigate the reliability of the interface, in this study, metallic pin contacts made of copper-nickel-tin alloy (CuNiSn) and bronze (CuSn6) are encapsulated with standard EMC materials. The metal surfaces made of CuNiSn are further coated with silver (Ag) and tin (Sn). An injection molding tool to produce test specimens is designed and manufactured according to the design rules of EMC processing. The reliability of the metal-plastic interfaces are investigated by means of shear and leak tests. The results of the investigations show that the reliability of the metal-plastic joints can be increased by using different material combinations.
Open Access
Characterization of wire-bonding on LDS materials and HF-PCBs for high-frequency applications
(2022) Guenther, Thomas; Werum, Kai; Müller, Ernst; Wolf, Marius; Zimmermann, André
Thermosonic wire bonding is a well-established process. However, when working on advanced substrate materials and the associated required metallization processes to realize innovative applications, multiple factors impede the straightforward utilization of the known process. Most prominently, the surface roughness was investigated regarding bond quality in the past. The practical application of wire bonding on difficult-to-bond substrates showed inhomogeneous results regarding this quality characteristic. This study describes investigations on the correlation among the surface roughness, profile peak density and bonding quality of Au wire bonds on thermoplastic and thermoset-based substrates used for high-frequency (HF) applications and other high-end applications. FR4 PCB (printed circuit board flame resitant class 4) were used as references and compared to HF-PCBs based on thermoset substrates with glass fabric and ceramic filler as well as technical thermoplastic materials qualified for laser direct structuring (LDS), namely LCP (liquid crystal polymer), PEEK (polyether ether ketone) and PTFE (polytetrafluoroethylene). These LDS materials for HF applications were metallized using autocatalytic metal deposition to enable threedimensional structuring, eventually. For that purpose, bond parameters were investigated on the mentioned test substrates and compared with state-of-the-art wire bonding on FR4 substrates as used for HF applications. Due to the challenges of the limited thermal conductivity and softening of such materials under thermal load, the surface temperatures were matched up by thermography and the adaptation of thermal input. Pull tests were carried out to determine the bond quality with regard to surface roughness. Furthermore, strategies to increase reliability by the stitch-on-ball method were successfully applied.
Open Access
Development and proof of concept of a miniaturized MEMS quantum tunneling accelerometer cased on PtC tips by focused ion beam 3D nano-patterning
(2021) Haub, Michael; Bogner, Martin; Guenther, Thomas; Zimmermann, André; Sandmaier, Hermann
Most accelerometers today are based on the capacitive principle. However, further miniaturization for micro integration of those sensors leads to a poorer signal-to-noise ratio due to a small total area of the capacitor plates. Thus, other transducer principles should be taken into account to develop smaller sensors. This paper presents the development and realization of a miniaturized accelerometer based on the tunneling effect, whereas its highly sensitive effect regarding the tunneling distance is used to detect small deflections in the range of sub-nm. The spring-mass-system is manufactured by a surface micro-machining foundry process. The area of the shown polysilicon (PolySi) sensor structures has a size smaller than 100 µm × 50 µm (L × W). The tunneling electrodes are placed and patterned by a focused ion beam (FIB) and gas injection system (GIS) with MeCpPtMe3 as a precursor. A dual-beam system enables maximum flexibility for post-processing of the spring-mass-system and patterning of sharp tips with radii in the range of a few nm and initial distances between the electrodes of about 30-300 nm. The use of metal–organic precursor material platinum carbon (PtC) limits the tunneling currents to about 150 pA due to the high inherent resistance. The measuring range is set to 20 g. The sensitivity of the sensor signal, which depends exponentially on the electrode distance due to the tunneling effect, ranges from 0.4 pA/g at 0 g in the sensor operational point up to 20.9 pA/g at 20 g. The acceleration-equivalent thermal noise amplitude is calculated to be 2.4-3.4 mg/√Hz. Electrostatic actuators are used to lead the electrodes in distances where direct quantum tunneling occurs.
Open Access
Direct processing of PVD hard coatings via focused ion beam milling for microinjection molding
(2023) Ruehl, Holger; Guenther, Thomas; Zimmermann, André
Hard coatings can be applied onto microstructured molds to influence wear, form filling and demolding behaviors in microinjection molding. As an alternative to this conventional manufacturing procedure, “direct processing” of physical-vapor-deposited (PVD) hard coatings was investigated in this study, by fabricating submicron features directly into the coatings for a subsequent replication via molding. Different diamondlike carbon (DLC) and chromium nitride (CrN) PVD coatings were investigated regarding their suitability for focused ion beam (FIB) milling and microinjection molding using microscope imaging and areal roughness measurements. Each coating type was deposited onto high-gloss polished mold inserts. A specific test pattern containing different submicron features was then FIB-milled into the coatings using varied FIB parameters. The milling results were found to be influenced by the coating morphology and grain microstructure. Using injection–compression molding, the submicron structures were molded onto polycarbonate (PC) and cyclic olefin polymer (COP). The molding results revealed contrasting molding performances for the studied coatings and polymers. For CrN and PC, a sufficient replication fidelity based on AFM measurements was achieved. In contrast, only an insufficient molding result could be obtained for the DLC. No abrasive wear or coating delamination could be found after molding.
Open Access
Experimental study on surface roughness and residual stress development in loose-abrasive polishing of hardened tool steel
(2025) Ruehl, Holger; Li, Yuxuan; Guenther, Thomas; Breidenstein, Bernd; Zimmermann, André
The repeatability and control of the achievable surface integrity in manual loose-abrasive diamond polishing of workpieces is very limited. In this study, first effects of polishing on the surface roughness and on induced near-surface residual stress of hardened tool steel X37CrMoV5-1 using an automatic metallographic grinder polisher have been investigated. The results show different effects of polishing parameters such as grain size, platen speed and forces applied to the workpiece on roughness and residual stress. XRD measurements of the residual stress depth profile showed a reduction in compressive stress which could be explained by the material removal mechanism and direction.
Open Access
FIB-SEM tomography for porosity characterization of inkjet printed nanoparticle gold ink
(2024) Ruehl, Holger; Reguigui, Hajer; Guenther, Thomas; Zimmermann, André
Inkjet printing is a versatile technology for the manufacturing of electronic devices to be used in various applications [1,2]. Common inks to create conductive layers are suspensions of a solvent with metal nanoparticles such as gold or silver [3]. After the deposition and solidification of an ink on a substrate, the metal nanoparticles are sintered to realize the conductivity of the printed layer. A porous, solid metal matrix remains, whereby the conductivity of the metal layer tends to be dependent on the porosity. To characterize the porosity of inkjet printed conductive layers, focused ion beam-scanning electron microscope (FIB-SEM) tomography is suggested as a potential characterization method in the presented study. For the experiment, a wafer diced silicon substrate with size of 10 x 10 mm² was used, onto which a 1.2 µm thin layer of commercially available nanoparticle gold ink was inkjet printed and then sintered. Subsequently, a four-step procedure for the FIB-SEM tomography-based porosity characterization was performed: 1) FIB preparation of the volume of interest (VOI), 2) serial sectioning including image acquisition, 3) image processing and 4) 3D-reconstruction and porosity analysis. The steps 1) and 2) were conducted using a FIB-SEM dual beam system ZEISS AURIGA 40 (Carl Zeiss Microscopy Deutschland GmbH, Germany). Prior to serial sectioning, a thin platinum layer was FIB induced deposited on top of the inkjet printed gold layer. A cube-shaped VOI with the size 5000 x 6000 x 5000 nm³ was then prepared by FIB milling. The surface to be sectioned was end face polished and a line trench serving as a reference marker for the image processing was milled along the VOI. The prepared VOI prior to FIB sectioning is shown in Figure 1. a). Next, the serial sectioning was conducted. The ion acceleration voltage was set to 30 kV. The aperture current was set to 50 pA, resulting in an ion beam spot size of 12.5 nm, which corresponds to the section slice thickness. No melting and re-sintering of the solid metal structure could be observed during sectioning. SEM images of the revealing surface areas were acquired with 1024 x 768 pixels image resolution and a pixel size of 5.82 nm. Both a secondary electron (SE) detector as well as a backscattered electron (BSE) detector were used for imaging. In total, a 2D stack of 368 SEM images was recorded. For comparison of individual sections, Figure 1. b) and c) show BSE detector images of the cross-sectioned VOI after slice 70 and slice 140. One can clearly see that the size and distribution of sintered metal particles varies along the VOI, forming a porosity network within the solid gold. Since the images acquired with the BSE detector presented a higher contrast and thus, a better distinction between the pores and the metal structure, these images were used for the image processing and final porosity analysis, for which the software AVIZO (Thermo Fisher Scientific Inc., USA) was used. First, the 2D images were aligned to correct for the shifts which occurred during the serial sectioning. Then, a sub-VOI was cropped out to exclude the reference line. The new 3D VOI was of a size of 3026 x 1164 x 2750 nm³, representing a stack of BSE detector images ranging from slice 30 to 250. Noise interference was minimized by applying a Gaussian filter. Afterwards, thresholding was applied as a segmentation technique to differentiate between pores and the solid gold as well as erosion as morphological operation. As a result, a reconstructed 3D model of the pores located in the solid gold was obtained, as shown in Figure 2. a). Using this 3D pore model, the number of pores and their diameters within the VOI could be determined. For the calculation of the pore diameters, each pore was considered to be of a spherical shape. A total of 1509 pores was counted. The pore diameter distribution is shown in the box plot in Figure 2. b). As it can be obtained from Figure 2. b), a pore size of 23 nm represents the lower quartile, while a pore size of 112 nm represents the upper quartile. The median pore size is 44 nm, while the mean is 63 nm, which indicates a trend towards smaller pores surrounded by larger pores. Based on the obtained results, FIB-SEM tomography with subsequent image processing is assessed by the authors to be a proper method to characterize the porosity of inkjet printed conductive layers, which was tested by means of a nanoparticle gold ink.
Open Access
Injection compression molded microlens arrays for hyperspectral imaging
(2018) Röder, Marcel; Drexler, Marc; Rothermel, Thilo; Meissner, Thomas; Guenther, Thomas; Zimmermann, André
Open Access
Injection compression molding of LDS-MID for millimeter wave applications
(2023) Wolf, Marius; Werum, Kai; Eberhardt, Wolfgang; Guenther, Thomas; Zimmermann, André
LDS-MIDs (laser direct structured mechatronic integrated devices) are 3D (three-dimensional) circuit carriers that are used in many applications with a focus on antennas. However, thanks to the rising frequencies of HF (high-frequency) systems in 5G and radar applications up to the mmWave (millimeter wave) region, the requirements regarding the geometrical accuracy and minimal wall thicknesses for proper signal propagation in mmWave circuits became more strict. Additionally, interest in combining those with 3D microstructures like trenches or bumps for optimizing transmission lines and subsequent mounting processes is rising. The change from IM (injection molding) to ICM (injection compression molding) could offer a solution for improving the 3D geometries of LDS-MIDs. To enhance the scientific insight into this process variant, this paper reports on the manufacturing of LDS-MIDs for mmWave applications. Measurements of the warpage, homogeneity of local wall thicknesses, and replication accuracy of different trenches and bumps for mounting purposes are presented. Additionally, the effect of a change in the manufacturing process from IM to ICM regarding the dielectric properties of the used thermoplastics is reported as well as the influence of ICM on the properties of LDS metallization - in particular the metallization roughness and adhesion strength. This paper is then concluded by reporting on the HF performance of CPWs (coplanar waveguides) on LDS-MIDs in comparison to an HF-PCB.
Open Access
Injection molding of encapsulated diffractive optical elements
(2023) Wagner, Stefan; Treptow, Kevin; Weser, Sascha; Drexler, Marc; Sahakalkan, Serhat; Eberhardt, Wolfgang; Guenther, Thomas; Pruss, Christof; Herkommer, Alois; Zimmermann, André
Microstructuring techniques, such as laser direct writing, enable the integration of microstructures into conventional polymer lens systems and may be used to generate advanced functionality. Hybrid polymer lenses combining multiple functions such as diffraction and refraction in a single component become possible. In this paper, a process chain to enable encapsulated and aligned optical systems with advanced functionality in a cost-efficient way is presented. Within a surface diameter of 30 mm, diffractive optical microstructures are integrated in an optical system based on two conventional polymer lenses. To ensure precise alignment between the lens surfaces and the microstructure, resist-coated ultra-precision-turned brass substrates are structured via laser direct writing, and the resulting master structures with a height of less than 0.002 mm are replicated into metallic nickel plates via electroforming. The functionality of the lens system is demonstrated through the production of a zero refractive element. This approach provides a cost-efficient and highly accurate method for producing complicated optical systems with integrated alignment and advanced functionality.
Open Access
Investigation of focused ion and electron beam platinum carbon nano-tips with transmission electron microscopy for quantum tunneling vacuum gap applications
(2021) Haub, Michael; Guenther, Thomas; Bogner, Martin; Zimmermann, André
To realize quantum tunneling applications with movable electrodes, sharp tips with radii down to several tens of nanometers are necessary. The use of a focused ion beam (FIB) and focused electron beam (FEB) with a gas injection system (GIS) allows the integration of geometries in the nanoscale directly into micro and nano systems. However, the implementation of the tunneling effect clearly depends on the material. In this work, a metal-organic precursor is used. The investigation of the prepared tunneling electrodes enables an insight into FIB/FEB parameters for the realization of quantum tunneling applications. For this purpose, a high-resolution transmission electron microscopy (HRTEM) analysis is performed. The results show a dependence of the material nanostructure regarding platinum (Pt) grain size and distribution in an amorphous carbon matrix from the used beam and the FIB currents. The integration of the tips into a polysilicon (PolySi) beam and measuring the current signal by approaching the tips show significant differences in the results. Moreover, the approach of FEB tips shows a non-contact behavior even when the tips are squeezed together. The contact behavior depends on the grain size, proportion of platinum, and the amount of amorphous carbon in the microstructure, especially at the edge area of the tips. This study shows significant differences in the nanostructure between FIB and FEB tips, particularly for the FIB tips: The higher the ion current, the greater the platinum content, the finer the grain size, and the higher the probability of a tunneling current by approaching the tips.
Open Access
Mass-producible micro-optical elements by injection compression molding and focused ion beam structured titanium molding tools
(2020) Ristok, Simon; Roeder, Marcel; Thiele, Simon; Hentschel, Mario; Guenther, Thomas; Zimmermann, André; Herkommer, Alois; Giessen, Harald
Open Access
Open-eco-innovation for SMEs with pan-European key enabling technology centres
(2020) Civelek, Faruk; Kulkarni, Romit; Fritz, Karl-Peter; Meyer, Tanja; Troulos, Costas; Guenther, Thomas; Zimmermann, André
The project “key enabling technologies for clean production” (KET4CP), which is supported by the European Commission, has the aim to connect small and medium-sized enterprises (SME) and Technology Centres (TC) for cleaner, greener and more efficient production. Within this context, SMEs and TCs across Europe work together to establish an open-innovation network and to raise awareness in productivity and environmental performance. This article presents how an open European network of TCs opens its innovation process to support SMEs to become cleaner, greener and more efficient. Furthermore, this article shows how the TCs and SMEs become a part of the open-eco-innovation platform in clean production and how successful the open-eco-innovation process of different European countries is. We revealed that a pan-European open innovation process for eco-innovations with TCs for key enabling technologies (KET TCs) and Enterprise Europe Network partners (EEN) is a successful approach for SMEs that want to produce and develop cleaner products. An application example is mentioned, in which TCs from different European countries have contributed to developing a product of a SME for energy harvesting. The SME, together with the TCs, developed a generator that is installed in city-level water supply pipes and so, it is outstanding in its application. This innovative application is also described in this article.
Open Access
Reliability study of electronic components on board-level packages encapsulated by thermoset injection molding
(2020) Kulkarni, Romit; Soltani, Mahdi; Wappler, Peter; Guenther, Thomas; Fritz, Karl-Peter; Groezinger, Tobias; Zimmermann, André
A drastically growing requirement of electronic packages with an increasing level of complexity poses newer challenges for the competitive manufacturing industry. Coupled with harsher operating conditions, these challenges affirm the need for encapsulated board-level (2nd level) packages. To reduce thermo-mechanical loads induced on the electronic components during operating cycles, a conformal type of encapsulation is gaining preference over conventional glob-tops or resin casting types. The availability of technology, the ease of automation, and the uncomplicated storage of raw material intensifies the implementation of thermoset injection molding for the encapsulation process of board-level packages. Reliability case studies of such encapsulated electronic components as a part of board-level packages become, thereupon, necessary. This paper presents the reliability study of exemplary electronic components, surface-mounted on printed circuit boards (PCBs), encapsulated by the means of thermoset injection molding, and subjected to cyclic thermal loading. The characteristic lifetime of the electronic components is statistically calculated after assessing the probability plots and presented consequently. A few points of conclusion are summarized, and the future scope is discussed at the end.
Open Access
Review on fabrication technologies for optical mold inserts
(2019) Röder, Marcel; Guenther, Thomas; Zimmermann, André
Polymer optics have gained increasing importance in recent years. With advancing requirements for the optical components, the fabrication process remains a challenge. In particular, the fabrication of the mold inserts for the replication process is crucial for obtaining high-quality optical components. This review focuses on fabrication technologies for optical mold inserts. Thereby, two main types of technologies can be distinguished: fabrication methods to create mold inserts with optical surface quality and methods to create optical microstructures. Since optical mold inserts usually require outstanding form accuracies and surface qualities, a focus is placed on these factors. This review aims to give an overview of available methods as well as support the selection process when a fabrication technology is needed for a defined application. Furthermore, references are given to detailed descriptions of each technology if a deeper understanding of the processes is required.
Open Access
Surface optimization of micro-integrated reflective optical elements by thermoset injection molding
(2020) Guenther, Thomas; Diegel, Lars; Roeder, Marcel; Drexler, Marc; Haybat, Mehmet; Wappler, Peter; Soltani, Mahdi; Zimmermann, André
Thermoset materials offer a multitude of advantageous properties in terms of shrinkage and warpage as well as mechanical, thermal and chemical stability compared to thermoplastic materials. Thanks to these properties, thermosets are commonly used to encapsulate electronic components on a 2nd-level packaging prior to assembly by reflow soldering on printed circuits boards or other substrates. Based on the characteristics of thermosets to develop a distinct skin effect due to segregation during the molding process, the surface properties of injection molded thermoset components resemble optical characteristics. Within this study, molding parameters for thermoset components are analyzed in order to optimize the surface quality of injection molded thermoset components. Perspectively, in combination with a reflective coating by e.g., physical vapor deposition, such elements with micro-integrated reflective optical features can be used as optoelectronic components, which can be processed at medium-ranged temperatures up to 230 °C. The obtained results indicate the general feasibility since Ra values of 60 nm and below can be achieved. The main influencing parameters on surface quality were identified as the composition of filler materials and tool temperature.
Open Access
Use of PtC nanotips for low-voltage quantum tunneling applications
(2022) Haub, Michael; Guenther, Thomas; Bogner, Martin; Zimmermann, André
The use of focused ion and focused electron beam (FIB/FEB) technology permits the fabrication of micro- and nanometer scale geometries. Therefore, FIB/FEB technology is a favorable technique for preparing TEM lamellae, nanocontacts, or nanowires and repairing electronic circuits. This work investigates FIB/FEB technology as a tool for nanotip fabrication and quantum mechanical tunneling applications at a low tunneling voltage. Using a gas injection system (GIS), the Ga-FIB and FEB technology allows both additive and subtractive fabrication of arbitrary structures. Using energy dispersive X-ray spectroscopy (EDX), resistance measurement (RM), and scanning tunneling microscope (STM)/spectroscopy (STS) methods, the tunneling suitability of the utilized metal–organic material–platinum carbon (PtC) is investigated. Thus, to create electrode tips with radii down to 15 nm, a stable and reproducible process has to be developed. The metal–organic microstructure analysis shows suitable FIB parameters for the tunneling effect at high aperture currents (260 pA, 30 kV). These are required to ensure the suitability of the electrodes for the tunneling effect by an increased platinum content (EDX), a low resistivity (RM), and a small band gap (STM). The STM application allows the imaging of highly oriented pyrolytic graphite (HOPG) layers and demonstrates the tunneling suitability of PtC electrodes based on high FIB aperture currents and a low tunneling voltage.