Laser micromachining / microfabrication By: Divya Bandi

1. Laser micromachining / microfabrication By: Divya Bandi Overview Interaction of lasers with materials Continued… • There should be a well precision and good handling mechanisms in manufacturing micro devices with these methods as some of the materials used for manufacturing are sensitive • Laser Drilling and applications: • It is one of the earliest method in material processing & it is 1-dimensional. • It is most extensively used in aerospace, aircraft and automotive industries. • It is a noncontact, precise and reproducible technique. • Laser Cutting and applications: • It is a two-dimensional machining process. • It is a high speed, repeatable and reliable method. • It is particularly suited fully or semi-automated cutting process. • It is used to cut steels, super alloys, aluminum, copper etc. • Three Dimensional Laser Machining and applications: • Laser Assisted Machining(LAM) & Laser Machining(LM) are the two types in this method. • LAM is specially developed for difficult-to materials like ceramics & hard metals. • LM can be used using either one single laser beam or two intersecting laser beams to machining the hard materials like Si3N4,SiC, SiAlON & Al2O3. • Oxford Lasers, Resonetics, Laser Micromachining LTD, etc. are the Laser Micromachining companies. • Laser Micromachining LTD is one of the major leading company in the manufacturing of micro devices. • This company provides devices to many sectors like Biotechnology, Energy, Solar, Telecommunications, Microelectronics, Medical, Precision engineering etc. Example Figures showing Laser micromachining • Introduction • Interaction of lasers with materials • Manufacturing process • Laser Drilling, Laser Cutting, Laser Machining and Applications • Industrial Perspective • Example figures showing Laser Micromachining • References • The manufacturing of micro devices was made easy with the introduction of Ruby Laser in 1960. • Four types of lasers exists based on the material to be made. • They are: Solid-state lasers, Gas lasers, Semiconductor lasers & Dye lasers. • Wavelength ranging from Ultraviolet to Infrared makes us to use variety of lasers based on the material to be manufactured. • Accuracy and precision in making micro devices with laser has lead to the advancement of laser technology. • Reflection, Refraction, Absorption, Scattering & Transmission phenomena occur when laser radiation interacts with the material. • But absorption of radiation is the important and desired phenomena among all. • Heating, melting, vaporization, Plasma formation etc occurs when radiation is absorbed by the material. • The processing of these phenomena depends on the electromagnetic radiation characteristics and thermo-physical properties of the material. • Intensity, wavelength, polarization, angle of incidence, etc are the parameters of the laser. • The high frequency laser radiation hits the electrons of the materials and set them into motion with the force, • F = eE + e((v/c)*H). • v = velocity of electron, c = speed of light, • e = electronic charge, • E = Electric field strength, H = Magnetic field strength. • Due to the rapid motion of electrons, the material becomes hot and melted so that we can mold it according to our desired design. • There are three basic processing steps in manufacturing any micro device using laser technology. • Primary and Secondary manufacturing processes: Casting, Forging, Rolling, Extrusion etc. are primary manufacturing processes. Whereas various machining and forming processes are secondary manufacturing processes. • Hot working and Cold working processes:Hot working process is the manufacturing process which is carried out at the temperature above the recrystallization temperature. Whereas below the recrystallization temperature are referred as Cold working processes. • Metal forming and Metal removal processes: Rolling, Forging and Bending are referred as Metal forming processes whereas various machining processes referred as Metal removal processes to bring out the desired shape from the material. • Apart from these, Laser drilling, Laser Cutting and Laser Machining are considered as the three important process to be involved in manufacturing any kind of desired micro device. Introduction Fig – 1. Gaskets cut from silicon. Manufacturing Processes Interaction of Lasers with Materials Fig – 2. Micro Needles.. References • http://www.lasermicromachining.com/downloads/Med-Tech_Innovation_Feb12.pdf • http://www.lasermicromachining.com/index.php • Dahotre, N. B., & Harimkar, S. P. (2008). Laser fabrication and machining of materials. New York, N.Y.: Springer Science+Business Media. • http://www.lasermicromachining.com/_images/materials/polymers/Gaskets_cut_from_silicone_sheet.jpg [Fig -1] • http://www.rsc.org/images/microneedles-300_tcm18-110963.jpg [Fig -2] Industrial Perspective