High Precision Femtosecond Laser Micromachining for Rapid Manufacture of MEMS Devices

2003 ◽  
Author(s):  
A. Bulusu ◽  
S. P. Joshi ◽  
P. S. Shiakolas
Keyword(s):  
Electrical Discharge Machining ◽  
Beam Quality ◽  
Focal Length ◽  
Chemical Vapor ◽  
Laser Micromachining ◽  
Inert Gases ◽  
Mems Devices ◽  
Machined Surface ◽  
Rapid Manufacture

Laser assisted machining in the MEMS context is gaining recognition due to its versatility in application and its cost effectiveness compared to processes such as LIGA, chemical vapor deposition, electrical discharge machining etc. High thermal conductivity causes instant heat transfer to the surroundings leading to significant heat affected zones. Damage to the surroundings is further aggravated by high ablation thresholds for metals when excimer lasers are used. Ultrashort pulse lasers have been found to minimize thermal damage to the surroundings more than any other known laser. Peak power densities cause direct evaporation and plasma formation of the material. High-pressure shock waves at the machined surface transfer the particles away from the spot preventing material redeposition around the feature. In this paper, we explore the use of femtosecond lasers for rapid manufacturing of MEMS devices through laser micromachining of master molds that can be used in replication processes such as hot embossing and injection molding. The effect of various factors that affect the size and quality of the machined feature such as beam quality, length of beam path, beam waist, polarization, energy per pulse and focal length of the lens used is investigated. The effect of various materials along with the use of vacuum and inert gases on the quality of the cut is also This work aims at laying the foundation for the development of a comprehensive database on the effect of various factors that need to be considered in the design of a laser micromachining system for rapid manufacture of MEMS devices.

scholarly journals 302 Evaluation of Machined Surface Quality of Long Fiber FRM by Electrical Discharge Machining

2000 ◽  
Vol 2000.53 (0) ◽  
pp. 49-50
Author(s):  
Rikio HIKIJI ◽  
Yoshihiro KAWANO ◽  
Koji ABURADA ◽  
Masakazu HARADA ◽  
Minoru ARAI
Keyword(s):  
Surface Quality ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Machined Surface ◽  
Machined Surface Quality

Pulsed Nd:YAG laser machining of nitinol: An experimental investigation

2021 ◽  
pp. 251659842110154
Author(s):  
B. Muralidharan ◽  
K. Prabu ◽  
G. Rajamurugan
Keyword(s):  
Nd:Yag Laser ◽  
Electrical Discharge Machining ◽  
Beam Quality ◽  
Cutting Speed ◽  
Recast Layer ◽  
Machining Process ◽  
Machined Surface ◽  
Pulsed Nd:Yag Laser ◽  
High Pulse Frequency ◽  
Micro Channels

Nickel–Titanium (Ni-Ti) shape memory alloy, commonly called nitinol alloys, finds its primary application in the production of biomedical implants, mainly because of itsrare properties such asshape memory, superelasticity and superior biocompatibility. Laser cutting is anon-traditional machining process for the production ofparts with close tolerances andcomplex geometry. Electrical discharge machining (EDM) of nitinol is associated with more heat-affected zone (HAZ) and recast layer thickness. This article aims to study nitinol’s machining characteristics by alaser source with good beam quality to have a less HAZ, recast layer and striations. Experiments were designed and carried out using central composite designs (CCD) by a pulsed Nd:YAG laser. Analysis based on the different parameters chosen was conducted to determine the parameters; effects, including laser power, frequency and cutting speed concerning the surface roughness. From the results, it is observed that the presence of HAZ is measured up to1. 48 mm from the machined surface. The topography analysis reveals that the striation is identified at high speeds, with less pulse overlapping by columnar micro channels, which can be reduced at high pulse frequency.

Prediction of the heat-affected zone of tool steel EN X37CrMoV5-1 after die-sinking electrical discharge machining

2016 ◽  
Vol 232 (8) ◽  
pp. 1395-1406 ◽  
Author(s):  
L’uboslav Straka ◽  
Slavomíra Hašová
Keyword(s):  
Mathematical Models ◽  
Heat Affected Zone ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Advanced Technology ◽  
Technological Parameters ◽  
Machined Surface ◽  
Knowledge Database ◽  
Subsurface Layers

This article describes the results of the experimental research on the heat-affected zone of the subsurface layers of eroded surface on medium-alloyed samples of steel EN X37CrMoV5-1 (W.-Nr. 1.2343) which occurs in die-sinking electrical discharge machining with Cu electrode. It assesses the direct effect and consequences of the heat-affected zone on the final quality of the machined surface. The aim of the experiments was to contribute to the knowledge database defining the influence of the main technological parameters of electrical discharge machining on the microhardness changes and the total depth of the heat-affected zone of the subsurface layers of experimental samples. The results of the experimental measurement were transformed into the mathematical models allowing simulation and prediction of the final quality of the machined surface after die-sinking electrical discharge machining tool steels with Cu electrode. The purpose of the mathematical models is to determine the optimal combination of process parameters and thereby achieve the desired quality of the products produced by this advanced technology.

Influence of Process Parameters on Geometric Precision of Machined Surface after WEDM

2017 ◽  
Vol 756 ◽  
pp. 107-118
Author(s):  
Ľuboslav Straka ◽  
Slavomíra Hašová
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Negative Impact ◽  
Geometric Accuracy ◽  
Machined Surface ◽  
Influence Of Process Parameters ◽  
Geometric Precision ◽  
Geometric Size ◽  
Nominal Surface

Geometrical precision machined surface is generally understood as mainly precision shape, orientation, location and run-out. As a rule, it is measuring the appropriate deviations from the nominal surface. The geometric size of this deviation from the nominal surface can in practice affect the conventionally measured value for the dimension and the dimension whilst maintaining the required tolerance. Because the WEDM technology is among the most accurate technology, the small final geometric accuracy deviation has also a negative impact on the final quality of the machined surface. The paper aimed to describe errors geometrical precision of machined surface which occurs in wire electrical discharge machining (WEDM) and quantify their scope.

scholarly journals Influence of MTP on Surface Roughness and Geometric Accuracy of Machined Surface at WEDM

2020 ◽  
Vol 5 (2) ◽  
pp. 91-97
Author(s):  
Luboslav Straka ◽  
Gabriel Dittrich
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Geometric Accuracy ◽  
Technological Parameters ◽  
Machined Surface ◽  
Number Of Factors ◽  
Progressive Technology ◽  
Quality Of Products ◽  
The Impact

Electrical discharge machining technology is one of the most precise machining methods. Therefore, even the smallest deviation of micro and macro geometry generally has a significant impact on the overall quality of products produced by this progressive technology. The quality of the machined surface after Wire Electrical Discharge Machining (WEDM) is influenced by a large number of factors, most of which are influenced by the Main Technological Parameters (MTP). The aim of the paper was to describe the results of experimental research aimed at assessing the impact of MTP for WEDM on the quality of machined surface in terms of geometric accuracy and roughness parameters Ra and Rz. The samples were made of high alloyed ledeburitic chromium-molybdenum-vanadium steel designated EN X155CrVMo12-1 on a Sodick AQ535 electroerosion machine. The tool used was a standard compact brass wire  0.25 mm with the designation Elecut Brass CuZn37.

scholarly journals Dynamic Control of Discharge Energy During WEDM for the Purpose of Eliminating Vibrations of the Wire Tool Electrode

2021 ◽  
Vol 29 (4) ◽  
pp. 260-265
Author(s):  
Ľuboslav Straka ◽  
Patrik Kuchta
Keyword(s):  
Electrical Discharge Machining ◽  
Production Systems ◽  
Dynamic Control ◽  
High Strength ◽  
Tool Electrode ◽  
Discharge Process ◽  
Machined Surface ◽  
The Wire ◽  
Wedm Process

Abstract Production in all industry fields is currently affected by new scientific and technical knowledge and the requirements for its rapid deployment. In many cases, the most modern and highly sophisticated technical systems are applied. Simultaneously, fully automated production systems are rather successfully used and progressive production technologies are implemented. In most cases, there is an integral part of a management system that operates the challenging technological processes. These processes would not be executable without the system’s precise control, which provides a suitable precondition for ensuring the high quality of manufactured products. However, the customer’s demanding requirements are not always met. These involve increased requests for the quality of the final product due to the reduction of the tolerance band and application of high-strength materials. This paper aims to describe one of the solutions by which it is possible to achieve a higher quality of the machined surface after wire electrical discharge machining (WEDM). The solution proposes that through dynamic management, the WEDM process eliminates the vibrations of the wire tool electrode and thereby achieves a substantial increase in the quality of the eroded area in terms of its geometric accuracy. With the support of an extensive database of information with precise exchange of information, the proposed system will allow to control the electro discharge process with regard to the optimal way of operation of the electro discharge machine on the basis of individually selected conditions.

Effects of Polymer Particles Suspending in Dielectric Fluid on Surface Roughness of EDM

2010 ◽  
Vol 97-101 ◽  
pp. 4146-4149 ◽  
Author(s):  
Yao Yang Tsai ◽  
Chih Kang Chang
Keyword(s):  
Molecular Weight ◽  
Surface Roughness ◽  
Electrical Discharge Machining ◽  
Silicone Oil ◽  
Dielectric Fluid ◽  
Polymer Particles ◽  
Machined Surface ◽  
Machining Speed ◽  
Pani Salt

Suspending powder in dielectric fluid of EDM (electrical discharge machining) has been developed to improve the quality of machined surface recently. The used powders are usually Al, Cu, Cr and so on metal powder because conductive particle can increase the spark gap and improve surface roughness of machined surface. Semi-conductive powder, Si is also utilized for the sake of increasing machining speed. This paper presents a new tryout to suspend polymer particles in the dielectric fluid of EDM. Experimental results show that the EDM process with suspending polymer particles still can be carried out but its surface roughness is not so good in conventional EDM oil. However the conventional EDM oil was taken the replace of silicone oil, suspending polyaniline (PANI-emer) of high molecular weight (Mw~65000) has finer improvement even better than using Si powder. Its surface roughness achieves less than Ra 0.2μm at low concentration and will be decreased gradually with increasing the concentration of PANI-emer (Mw~65000). The surface roughness is Ra 0.14μm when the powders concentration is 10g/l. Even for different type of polyaniline shows different machining characteristics. The surfaces roughness becomes worse when the concentration of low molecular weight PANI-emer (Mw~20000) is higher. An electric-conductive PANI-salt powder has a rapid decrease of surface roughness with increasing its concentration than other materials.

Characterization of homoepitaxial diamond films by Electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 880-881
Author(s):  
D.P. Malta ◽  
S.A. Willard ◽  
R.A. Rudder ◽  
G.C. Hudson ◽  
J.B. Posthill ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Substrate Surface ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Large Degree ◽  
Rf Plasma ◽  
Semiconducting Diamond

Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. A major goal of current device-related diamond research is to achieve a high quality epitaxial film on an inexpensive, readily available, non-native substrate. One step in the process of achieving this goal is understanding the nucleation and growth processes of diamond films on diamond substrates. Electron microscopy has already proven invaluable for assessing polycrystalline diamond films grown on nonnative surfaces.The quality of the grown diamond film depends on several factors, one of which is the quality of the diamond substrate. Substrates commercially available today have often been found to have scratched surfaces resulting from the polishing process (Fig. 1a). Electron beam-induced current (EBIC) imaging shows that electrically active sub-surface defects can be present to a large degree (Fig. 1c). Growth of homoepitaxial diamond films by rf plasma-enhanced chemical vapor deposition (PECVD) has been found to planarize the scratched substrate surface (Fig. 1b).

Improvement in Gate Dielectric Quality of Ultra Thin a: SiN:H MNS Capacitor by Hydrogen Etching of the Substrate

2002 ◽  
Vol 716 ◽  
Author(s):  
Parag C. Waghmare ◽  
Samadhan B. Patil ◽  
Rajiv O. Dusane ◽  
V.Ramgopal Rao
Keyword(s):  
Silicon Nitride ◽  
Gate Dielectric ◽  
Substrate Surface ◽  
Scaling Limit ◽  
Tunneling Current ◽  
Chemical Vapor ◽  
Poor Performance ◽  
State Density ◽  
Direct Tunneling Current

AbstractTo extend the scaling limit of thermal SiO2, in the ultra thin regime when the direct tunneling current becomes significant, members of our group embarked on a program to explore the potential of silicon nitride as an alternative gate dielectric. Silicon nitride can be deposited using several CVD methods and its properties significantly depend on the method of deposition. Although these CVD methods can give good physical properties, the electrical properties of devices made with CVD silicon nitride show very poor performance related to very poor interface, poor stability, presence of large quantity of bulk traps and high gate leakage current. We have employed the rather newly developed Hot Wire Chemical Vapor Deposition (HWCVD) technique to develop the a:SiN:H material. From the results of large number of optimization experiments we propose the atomic hydrogen of the substrate surface prior to deposition to improve the quality of gate dielectric. Our preliminary results of these efforts show a five times improvement in the fixed charges and interface state density.

Improved surface quality of rotation symmetric structures by excimer laser micromachining

1997 ◽  
Author(s):  
H. K. Tönshoff ◽  
C. Graumann ◽  
M. Rinke ◽  
P. Lonergan ◽  
J. Wais
Keyword(s):  
Surface Quality ◽  
Excimer Laser ◽  
Laser Micromachining ◽  
Rotation Symmetric ◽  
Symmetric Structures
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