Alternative technology for fabrication of nano- or microstructured mould inserts used for optical components (original) (raw)
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AIP Conference Proceedings, 2015
Micro structured optical plastics components are intensively used i. e. in consumer electronics, for optical sensors in metrology, innovative LED-lighting or laser technology. Injection moulding has proven to be successful for the large-scale production of those parts. However, the production of those parts still causes difficulties due to challenges in the moulding and demoulding of plastics parts created with laser structured mould inserts. A complete moulding of the structures often leads to increased demoulding forces, which then cause a breaking of the structures and a clogging of the mould. An innovative approach is to combine PVD-coated (physical vapour deposition), laser structured inserts and a variothermal moulding process to create functional mic8iüro structures in a one-step process. Therefore, a PVD-coating is applied after the laser structuring process in order to improve the wear resistance and the anti-adhesive properties against the plastics melt. In a series of moulding trials with polycarbonate (PC) and polymethylmethacrylate (PMMA) using different coated moulds, the mould temperature during injection was varied in the range of the glass transition and the melt temperature of the polymers. Subsequently, the surface topography of the moulded parts is evaluated by digital 3D laser-scanning microscopy. The influence of the moulding parameters and the coating of the mould insert on the moulding accuracy and the demoulding behaviour are being analysed. It is shown that micro structures created by ultra-short pulse laser ablation can be successfully replicated in a variothermal moulding process. Due to the mould coating, significant improvements could be achieved in producing micro structured optical plastics components.
Replication of Micro Laser Textures by Injection Molding
Procedia Engineering, 2013
Increasingly micro technology becomes more important in order to develop new products with high added value. These new technologies known as micro allow us manufacturing precision components; these new micro components should work and take carrying out the functions previously performed by larger parts. Microinjection is one of these new technologies. This has the capacity to produce parts, for different materials both plastic and metal and for some industries and applications. The main objective in this paper is to determine the replicate microtextures capability for plastic injection molds. For our samples, ABS plastic is injected into four aluminum cavities with different laser textures performed in, using different technologies to get them. In order to analyze how mold texture affects parts, optical interferometry technique was selected to measure it. The superficial topography obtained was processed using MountainsMap software, in order to get the replicability of injected parts. It has also been used an electron microscopy (SEM) to evaluate the mold textures and injected parts in a photographically way.
Fabrication of Moulds and Dies Using Precision Laser Micromachining and Micromilling Technologies
Journal of Laser Micro Nanoengineering, 2008
This paper presents results obtained from our studies on the 3D laser micromachining and micromilling technologies. Specific examples of micro moulds and dies, fabricated using these techniques, are presented. The layer-by-layer material removal for 3D precision laser micromachining was proposed and the required process parameters were identified. Specifically, the process parameters, such as overlap between grooves and number of passes per layer, were investigated. The results were then applied to fabricate a "Cross Sign" die with overall dimensions of 2.5x2.5 mm and a wall width of 50 μm in mild steel A20 material. The finished micro die had a surface roughness of <0.35 μm and contour geometric errors within +/-2 μm. For comparison purpose, the same "Cross Sign" microdie was fabricated using the micromilling process from brass and replicated on PMMA through the hot embossing process. Geometric errors within +/-1 μm and a surface roughness inside the rectangular channels of 9.9 nm were achieved. The paper discusses challenges met during fabrication of the dies along with a comparative analysis of the geometric quality.
Replication of diffractive optical elements by injection molding
SPIE Proceedings, 2004
In this paper we describe the replication processes of DOE carried out at the Diffractive Optics Laboratory I UNICAMP for replicating DOE. In particular we present the results obtained in the replication by injection molding of microlens array, diffraction gratings and polarizing elements. The measurements of the geometric dimensions of the DOE masters, the nickel shims and the replicated structures were accomplished by perfilometry, AFM and SEM microscopy. The optical properties ofboth the DOE masters and their replicas were evaluated by measuring ofthe diffraction efficiency as a function ofthe incident wavelength, for orthogonal polarizations.
Micromanufacturing: A review—part II
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture
This article discusses an overview of microforming, microcasting and microwelding processes. In the case of microforming, the processes reviewed are micro deep drawing, microforging, microextrusion, microrolling, microstamping, microhydroforming and incremental microforming. This section also throws some light on how the lasers have been used for microbending and micropunching purposes. The work done in the area of physics of microforming processes has also been discussed briefly. This article also deals with different types of microcasting processes particularly permanent mold and investment microcasting processes. The applications of these microcasting processes have been specified in different fields of engineering, biomedical and so on. Some areas in which further research work is needed have been identified. It includes both theoretical and experimental works which need attention. The last part of this article deals with microjoining in general and laser microjoining in particular. This section discusses the types of the lasers that are being used for microjoining purposes. The process parameters (laser, optics, system and material) have been explained, and some work done on the parametric analysis has been reported briefly. Various applications of laser microjoining have been elaborated before the last section on concluding remarks. This last section presents, in very brief, the areas in which further work is required in microjoining processes.
Wafer-scale micro-optics fabrication
Micro-optics is an indispensable key enabling technology for many products and applications today. Probably the most prestigious examples are the diffractive light shaping elements used in high-end DUV lithography steppers. Highly-effi cient refractive and diffractive micro-optical elements are used for precise beam and pupil shaping. Micro-optics had a major impact on the reduction of aberrations and diffraction effects in projection lithography, allowing a resolution enhancement from 250 nm to 45 nm within the past decade. Micro-optics also plays a decisive role in medical devices (endoscopes, ophthalmology), in all laser-based devices and fi ber communication networks, bringing high-speed internet to our homes. Even our modern smart phones contain a variety of micro-optical elements. For example, LED fl ash light shaping elements, the secondary camera, ambient light and proximity sensors. Wherever light is involved, micro-optics offers the chance to further miniaturize a device, to improve its performance, or to reduce manufacturing and packaging costs. Wafer-scale micro-optics fabrication is based on technology established by the semiconductor industry. Thousands of components are fabricated in parallel on a wafer. This review paper recapitulates major steps and inventions in wafer-scale micro-optics technology. The state-of-the-art of fabrication, testing and packaging technology is summarized.
Investigation of the replication quality of plastic micro-optical interconnection components
2001
The technology of Deep Lithography with Protons (DLP) is a high-precision rapid prototyping technology for the fabrication of 3D monolithic micro-optical elements and micro-mechanical structures in PMMA. We report on our investigation on how to adapt this DLP process to be compatible with LIGA-based injection molding techniques and with vacuum casting replication technologies for the mass fabrication of 3D plastic micro-optical components. We highlight the progress made to optimize the vacuum casting technology to obtain optical quality. The examples we present are replicas of optical interconnection modules consisting of components such as microlenses and microprisms. 5. M. H. Ayliffe et al., Six-degrees-of-freedom alignment of two-dimensional array components using off-axis linear Fresnel zone plates, Appl. Optics, 2001. b c a
Microfabrication using silicon mold inserts and hot embossing
MHS'96 Proceedings of the Seventh International Symposium on Micro Machine and Human Science
We have successfully demonstrated the feasibility of fabricating three-dimensional microstructures by using a combined silicon mold insert and micro hot embossing process (SMIHE). Anisotropic silicon wet etching process has been used to define microstructures on top of a four inch silicon wafer. The whole wafer is then used as the mold insert in a micro hot pressing machine to duplicate plastic microstructures repeatedly. Fine micro pyramid shape microstructures with base width of 30 pm and height of about 21 pm have been fabricated by this method as a demonstration. They have very smooth surfaces and may be suitable for optical applications. This new process shows promise for achieving high yield, reliable fine micro structures on plastic films.