• Title/Summary/Keyword: Laser types

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Effects of shielding Gas Types on $CO_2$ Laser Weldability (보호가스에 따른 Tailored Blank 레이저 용접성 평가에 관한 연구)

  • 정봉근;유순영;박인수;이창희
    • Laser Solutions
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    • v.1 no.1
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    • pp.30-38
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    • 1998
  • This study includes the efface of shielding gas types on $CO_2$ laser weldability of low carbon automotive galvanized steel. The types of shielding gas evaluated are He, $CO_2$, Ar, $N_2$, 50%Ar+50%$N_2$. The weld penetration, strength, formability(Erichsen test) of Laser weld are found to be strongly dependent upon the types of shielding gas used. Further, the maximum travel speed and flow rate to form a keyhole weld is also dependent upon types of shielding gas. The ability of shielding gas in removing plasma plume and thus increasing weld penetration is believed to be closely related with ionization/dissociation potential, which determine the period of plasma formation and disappearance. Further, thermal conductivity and reactivity of gas with molten pool also give strong effect on penetration and porosity formation which in turn affect on the formability and strength.

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Laser Micro Soldering and Soldering Factors (레이저 마이크로 솔더링과 솔더링 인자)

  • Hwang, Seung Jun;Hwang, Sung Vin;Jung, Jae Pil
    • Journal of the Microelectronics and Packaging Society
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    • v.27 no.3
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    • pp.1-8
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    • 2020
  • In this paper, the principles, characteristics and recent studies of the laser micro soldering are reviewed. The factors which influence laser micro welding and soldering are also included. Laser soldering is a non-contact process that transfers energy to solder joint by a precisely controlled laser beam. In recent electronics industry, the demands for laser soldering are increasing due to bonding for complex circuits and local heating in micro-joint. In laser soldering, there are several important factors like laser absorption, laser power, laser scanning speed, and etc, which affect laser solderability. The laser absorption ratio depends on materials, and each material has different absorption or reflectivity for the laser beam, which requires fine adjustment of the laser beam. Laser types and operating conditions are also important factors for laser soldering performance, and these are also reviewed.

Laser Micro-Joining and Soldering (레이저 마이크로 접합 및 솔더링)

  • Hwang, Seung Jun;Kang, Hye Jun;Kim, Jeng O;Jung, Jae Pil
    • Journal of the Microelectronics and Packaging Society
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    • v.26 no.3
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    • pp.7-13
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    • 2019
  • In this paper, the principles, types and characteristics of the laser and laser soldering are introduced. Laser soldering methods for electronics, metals, semiconductors are also presented. Laser soldering is a non-contact process that transfers energy to solder joint by a precisely controlled beam. Demands for laser soldering are increasing due to bonding for complex circuits and local heating in micro joint. Laser absorption ratio depends on materials, and each material has different absorption or reflectivity of the laser beam, which requires fine adjustment of the laser beam. Laser types and operating conditions are also important factors for laser soldering performance. In this paper, the performance of Nd:YAG laser soldering is compared to the hot blast reflow. Meanwhile, a diode laser gives different wavelength and smaller parts with high performance, but it has various reliability issues such as heat loss, high power, and cooling technology. These issues need to be improved in the future, and further studies for laser micro-joining and soldering are required.

Weldability in Nd:YAG Laser of Sintered Material Depend on Shielding Gases (보호가스에 따른 소결체의 Nd:YAG 레이저 용접성)

  • Kim, Yong;Yang, Hyun-Seok;Park, Ki-Young;Lee, Kyoung-Don
    • Laser Solutions
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    • v.10 no.4
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    • pp.1-6
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    • 2007
  • This study includes the effects of shielding gas types and flow rate on Nd:YAG Laser weldability of sintered material. The types of shielding gas were evaluated for He, Ar and N2. Bending strength, porosity rate, hardness and aspect ratio testing of laser weld are carried out to evaluated the weldability. As a results, Ar gas was showed the best welding strength even it has the most porosity content on weld metal, and depend on increases the gas flow rate, it was not only got deeper penetration depth but also showed higher bending strength. Therefore we could know that bending strength is not only affect the porosity content but also melting area.

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Comparison of Functional Voice Outcomes in Patients Treated with Laser Surgery and Radiation Therapy for Early Glottic Cancer (조기 성문암에서 레이저 수술과 방사선 치료 후 음성기능 비교)

  • Lee, Jong-Cheol;Lee, Yoon-Se;Nam, Soon-Yuhl
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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    • v.19 no.1
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    • pp.7-10
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    • 2008
  • The early glottic cancers are traditionally treated by radiotherapy or endoscopic surgery. The excellent effectiveness of both treatment modalities for local control, larynx preservation, and disease specific death is similar. Therefore, functional voice outcome after treatment is one of the most important factors in the choice of treatment for early glottic cancer. To assess the functional outcomes and compare the voice quality in patients with early glottic cancer treated with curative intent with radiotherapy or laser cordectomy, we performed literature review. Most studies showed that the voice quality after radiation therapy is slightly better than that after laser cordectomy. Subanalysis according to types of laser cordectomy, however, indicates that voice quality depends on type of laser cordectomy. Especially, type I or type II laser cordectomy might be superior to other types of laser cordectomy and radiation therapy. We conclude that the laser cordectomy is a good surgical alternative for properly selected early glottic cancer including professional voice users.

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Angle Calculation Rotation Angle of One-axis Manipulator in Laser Module (레이저모듈에서의 1-축 틸팅의 회전각 계산)

  • Jung, Dong-Won;Kim, Dong-Hong;Kim, Bong-Chun;Kim, Dong-Hyeon
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.5
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    • pp.506-509
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    • 2012
  • Laser assisted machining is the processing method that preheating brittle materials by laser heat source and cutting the soften area. This processing applied to various industries because it can be cutting difficult-to-cut materials. However, the laser assisted machining appeared the limitations of processing for equipped with the spindle. So, it assumed separate model that spindle and laser assisted machining. In feed, the calculation of changing the angle of the laser module according to preheat point and the shape of the feed is important and it tried easy calculating changing angle of 1-axis Manipulator in separate model. In 3 types feed shape, angle of 1-axis Manipulator was calculated when fixed and moved in the outside of spindle. In this study, suggest 2 types of methods for laser module when fixed and moved.

Combination Treatment of Nd:YAG Picosecond-domain Laser and Fractional CO2 Laser for Contracted Neck Scar with Hyperpigmentation

  • Choi, Woo Jung;Park, Eun Soo;Tak, Min Sung;Kang, Sang Gue
    • Medical Lasers
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    • v.10 no.1
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    • pp.52-54
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    • 2021
  • There is growing interest in minimizing postoperative scarring after a thyroidectomy. Among the many treatment types, laser therapy, especially picosecond-domain laser therapy, is accepted as a standard method. In the present case, a patient with a pigmented, contracted scar was treated using the combination of a picosecond laser and ablative fractional (AF) CO2 laser. After 15 sessions of 1,064-nm picosecond with micro lens array (MLA) and AF CO2 laser application, the patient showed significant improvement in their pigmented lesions and scar contracture with no noticeable side effects for 16 months. These results suggest that a combination of picosecond laser with MLA and AF CO2 laser can treat pigmented, contracted scars safely and effectively.

Controlled Surface Functionalities of metals using Femtosecond Laser-induced Nano- and Micro-scale Surface Structures (펨토초 레이저 유도 나노 및 마이크로 구조물을 활용한 금속 표면 기능성 제어)

  • Taehoon Park;Hyo Soo Lee;Hai Joong Lee;Taek Yong Hwang
    • Design & Manufacturing
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    • v.17 no.2
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    • pp.55-61
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    • 2023
  • With femtosecond (fs) laser pulse irradiation on metals, various types of nano- and micro-scale structures can be naturally induced at the surface through laser-matter interaction. Two notable structures are laser-induced periodic surface structures (LIPSSs) and cone/spike structures, which are known to significantly modify the optical and physical properties of metal surfaces. In this work, we irradiate fs laser pulses onto various types of metals, cold-rolled steel, pickled & oiled steel, Fe-18Cr-8Ni alloy, Zn-Mg-Al alloy coated steel, and pure Cu which can be useful for precise molding and imprinting processes, and adjust the morphological profiles of LIPSSs and cone/spike structures for clear structural coloration and a larger range of surface wettability control, respectively, by changing the fluence of laser and the speed of raster scan. The periods of LIPSSs on metals used in our experiments are nearly independent of laser fluence. Accordingly, the structural coloration of the surface with LIPSSs can be optimized with the morphological profile of LIPSSs, controlled only by the speed of the raster scan once the laser fluence is determined for each metal sample. However, different from LIPSSs, we demonstrate that the morphological profiles of the cone/spike structures, including their size, shape, and density, can be manipulated with both the laser fluence and the raster scan speed to increase a change in the contact angle. By injection molding and imprinting processes, it is expected that fs laser-induced surface structures on metals can be replicated to the plastic surfaces and potentially beneficial to control the optical and wetting properties of the surface of injection molded and imprinted products.

The Study on Wafer Cleaning Using Excimer Laser (엑사이머 레이저를 이용한 웨이퍼 크리닝에 관한 고찰)

  • 윤경구;김재구;이성국;최두선;신보성;황경현;정재경
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.743-746
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    • 2000
  • The removal of contaminants of silicon wafers has been investigated by various methods. Laser cleaning is the new dry cleaning technique to replace wafer wet cleaning in the near future. A dry laser cleaning uses inert gas jet to remove contaminant particles lifted off by the action of a KrF excimer laser. A laser cleaning model is developed to simulate the cleaning process and analyze the influence of contaminant particles and experimental parameters on laser cleaning efficiency. The model demonstrates that various types of submicrometer-sized particles from the front sides of silicon wafer can be efficiently removed by laser cleaning. The laser cleaning is explained by a particle adhesion model. including van der Waals forces and hydrogen bonding, and a particle removal model involving rapid thermal expansion of the substrate due to the thermoelastic effect. In addition, the experiment of wafer laser cleaning using KrF excimer laser was conducted to remove various contaminant particles.

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Excimer laser micromachining of silicon in liquid phase (액상에서의 엑시머 레이저 실리콘 미세가공)

  • Jang, Deok-Suk;Kim, Dong-Sik
    • Laser Solutions
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    • v.11 no.1
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    • pp.12-18
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    • 2008
  • Laser micromachining is a promising technique to fabricate the micro-scale devices. However, there remains important challenges to reducethe redeposition of ablated materials around the laser irradiated zone and to get a smooth surface, especially for metal and semiconductor materials. To achieve the high-quality micromachined devices, various methods have been developed. Liquid-assisted micromachining can be a good solution to overcome the previously mentioned problems. During the laser ablation process, the liquid around the solid sample dramatically changes the ablation characteristics, such as ablation rate, surface profile, formation of debris, and so on. In this investigation, we conducted the laser micromachining of Si in various liquid environmental conditions, such as liquid types, liquid thickness. In addition, using nanoscale time-resolved shadowgraphy technique, we observed the ablation process in liquid environments to understand the mechanism of liquid-assisted laser micromachining.

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