Mariusz Tomczyk

Ablation of selected conducting layers by fiber laser

Laser Direct Writing (LDW) are used in the manufacture of electronic circuits, pads, and paths in sub millimeter scale. They can also be used in the sensors systems. Ablative laser writing in a thin functional layer of material deposited on the dielectric substrate is one of the LDW methods. Nowadays functional conductive layers are composed from graphene paint or nanosilver paint, indium tin oxide (ITO), AgHTTM and layers containing carbon nanotubes. Creating conducting structures in transparent layers (ITO, AgHT and carbon nanotubes layers) may have special importance e.g. for flexi electronics. The paper presents research on the fabrication of systems of paths and appropriate pattern systems of paths and selected electronic circuits in AgHTTM and ITO layers deposited on glass and polymer substrates. An influence of parameters of ablative fiber laser treatment in nanosecond regime as well as an influence of scanning mode of laser beam on the pattern fidelity and on electrical parameters of a generated circuit was investigated.

Laser microscale technologies: modeling assisted processes

Set of different physical processes has crucial influence on the required precision in case of shaping of elements with dimensions less than tenths millimeter by means of a laser beam, both in terms of the 3D geometry and the structure of the material in micro-volume. Many issues in the field of micrometer scale materials can be solved and used in practice by modeling processes. This article presents some selected examples of accomplished laser microtechnologies, using beam of nanosecond pulses of fiber laser, successfully supported by computer modeling. Using a pulsed fiber laser beam in the process of a thermal ablation spatial structures of micro elements in ceramic and semiconductor materials were produced. Optimum range of process parameters to ensure efficient removal of material, and acceptable quality of a surface of made elements was set by modeling. In micro-technologies, where structures with submillimeter dimensions are formed, modeling of the process with the phase transition phenomena requires taking into account the energy coupling of a beam – material, nonlinear thermal phenomena and the difficult to modeling problems associated with moving phase boundary as well as latent heat of phase transition.

Semiconductor and Ceramic Microstructure Made by Single Mode Fiber Laser

In the paper the results of micromachining of 3D microstructures of microsystems made from silicon and alumina ceramic using a single mode fiber laser (1064 nm) are presented. The quality of obtained structures and its smallest dimensions with acceptable maintained quality were examined. The influence of variable parameters of laser processing with changing of mapping scale on geometrical features of structures was identified.

Laser Technologies in Microsystems

This article presents some results of laser processing of materials, used for the construction of microsystems and micro-sensors, e.g. Si, Al2O3 and zirconia ceramics. The necessity of faithful reproducing the geometry and dimensions in the micro-scale puts specific requirements for laser machining process. Laser micro-technologies must be conducted under conditions which ensure the perfect guidance of a well-focused laser beam, scanning at a suitable speed, and the laser pulse duration with proper repetition frequency. The amount of absorbed energy depends on wavelength of laser radiation and kind of material, which also influence on this process. All these conditions should take into account the need to maintain a small heat affected zone (HAZ). This guarantees keeping the true reproduction of micro-shapes and cutting edges with a different angle of lines even in micro-scale details. The present work confirms the possibility of using laser technology for such applications.

Thermokinetic processes in laser welding of current leads

The aim of this study was to investigate the usefulness of the laser welding technology for the realization of wire connections: semiconductor structure-outer leading in power devices. Laser technology can be alternative to the traditional ultrasonic method of bonding, applied in power devices (for example IGBT transistors). The bondings made by ultrasonic method have adhesive nature and therefore are more susceptible for the damage than laser welded joints.A laser beam of a wavelength of 1.06 μm was applied in the new method of leads joining. Nickel was used as a material for wire leads and an intermediate plate (Molybdenum) between semiconductor structure and wire was placed additionally. The wire was welded directly to this plate. In this paper the thermo-mechanical properties of these bonding will be presented. Two fundamental problems will be discussed: thermal stresses, induced during laser welding, which have influence on the behaviour of the joints, and thermal state of the finished leads during conducting great currents, typical for the work of the power devices. The results of experiment investigations and results of computer modeling will be also presented.The aim of this study was to investigate the usefulness of the laser welding technology for the realization of wire connections: semiconductor structure-outer leading in power devices. Laser technology can be alternative to the traditional ultrasonic method of bonding, applied in power devices (for example IGBT transistors). The bondings made by ultrasonic method have adhesive nature and therefore are more susceptible for the damage than laser welded joints.A laser beam of a wavelength of 1.06 μm was applied in the new method of leads joining. Nickel was used as a material for wire leads and an intermediate plate (Molybdenum) between semiconductor structure and wire was placed additionally. The wire was welded directly to this plate. In this paper the thermo-mechanical properties of these bonding will be presented. Two fundamental problems will be discussed: thermal stresses, induced during laser welding, which have influence on the behaviour of the joints, and thermal state of the finished leads during c...

Laser microtechnologies for passive elements of electronic circuits

Varied innovative laser-technologies introduced to manufacturing process of electronic circuits and devices were applied to semiconductor and dielectric materials. As distinct from this we have investigated some laser microtechnologies concerning electrically conductive materials and elements made of them. Laser technologies such as microremelting and microalloying of thin wires and metallic foils as well as microwelding and material removing were applied for creating of a new type of conductive elements. These elements containing micro-areas of form, dimensions and materials properties, especially high electrical resistivity, determined by applying of laser microtechnology, could be use as new generation of miniature fuse links. The problems of heat and mass transfer specific to remelting and alloying of elements of microscopic dimensions were investigated by computer modeling. The results of investigations into materials, electrical and thermal properties of modified elements are discussed with reference to results of experimental utilization of elements manufactured by means of laser technologies.Varied innovative laser-technologies introduced to manufacturing process of electronic circuits and devices were applied to semiconductor and dielectric materials. As distinct from this we have investigated some laser microtechnologies concerning electrically conductive materials and elements made of them. Laser technologies such as microremelting and microalloying of thin wires and metallic foils as well as microwelding and material removing were applied for creating of a new type of conductive elements. These elements containing micro-areas of form, dimensions and materials properties, especially high electrical resistivity, determined by applying of laser microtechnology, could be use as new generation of miniature fuse links. The problems of heat and mass transfer specific to remelting and alloying of elements of microscopic dimensions were investigated by computer modeling. The results of investigations into materials, electrical and thermal properties of modified elements are discussed with referenc...

Laser-Textured Rubbers with Carbon Nanotube Fillers

This paper describes a method of laser ablation for improving the hydrophobic properties of vulcanized rubber. The treatment was tested on acrylonitrile rubber (NBR) and styrene butadiene rubber (SBR) containing carbon nanotubes and soot as fillers. The surface layer of the vulcanizates was modified using a nanosecond-pulsed laser at 1060 nm wavelength. The parameters of the ablation process were congruent, so no chemical changes in the polymeric material were observed. Evaluation of the surface condition of the laser-textured samples was performed using a Leica MZ6 stereoscopic microscope, operating with MultiScan 8.0 image analysis software. The contact angles were determined for all the samples before and after the surface modification process. Following modification of the surface morphology, with the best parameters of laser ablation, the contact angle increased, reaching 147°, which is very close to the threshold of superhydrophobicity (150°). On the basis of the results from several tests, laser ablation with a fiber-pulsed laser can be considered a very useful method for producing rubbers with superhydrophobic surfaces.

Measurement of the average shear rate around a microparticle in the shear thinning medium with laser tweezers

ABSTRACT A novel method for the determination of the average shear rate around a microparticle moving in the fluid is presented. Although the shear rate around a particle moving in the fluid is a parameter of paramount importance in sedimentation studies, its determination is time-consuming, thus model-based solutions are preferred. However, the current literature models require still rigorous validation. The presented technique relies on optical tracking of a laser-tweezers trapped particle suspended in the liquid medium. The obtained experimental results for spherical particles of 1 micron diameter show a good agreement with the classical rheology and literature correlation models. The new method is a valuable tool for determination of sedimentation parameters as it reduces the time of experiments and the sample volume by order(s) of magnitude when compared to classical methods.

Durability and reliability enhancement of selected electronic components achieved by laser technologies

The article presents selected laser technologies designed to increase the reliability of some of electrical and electronic components. They include technology of connecting, surface modification or precise shaping. The technique of laser welding as more reliable joining than the traditional technique of thermo-compression and ultra-compression has been described. Our method of welding of thin wires in the power semiconductor devices and technology of welding stranded wires has been introduced. The paper also describes the technology of laser soldering, which causes creation of thinner intermetallic phases owing to a shorter heating times. The laser method of manufacturing of precision fuses is also presented. Selected results of laser method of modification of surface layer of contacts of switching electrodes have been also commented on herein.

Analysis of thermal and electrical properties of heating microsystems based on TCO layers

The analysis of thermal and electrical properties of laser patterned ITO (Indium Tin Oxide) structures on polymer substrate have been presented in this paper. We used ITO layers to produce the coupled microheater and sensor, which are closed in one microsystem. The proposed structure of heating system can be used in wide research area, especially in biology and medicine. The coupled heater and sensor enable development an accurate heating systems with possibility of temperature controlling.