• Title/Summary/Keyword: YAG-Laser

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A Study on Heat Transfer Characteristics of Laser Cutting for the CSP 1N Sheet Using High-power CW Nd:YAG Laser (고출력 CW Nd:YAG 레이저를 이용한 CSP 1N 박판 절단공정의 열전달 특성 분석)

  • Ahn, Dong-Gyu;Kim, Min-Su
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.5 no.1
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    • pp.51-58
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    • 2006
  • The objective of this research work is to investigate into heat transfer characteristics of the laser cutting of CSP 1N sheet using high power CW Nd:YAG laser. In order to investigate the heat transfer characteristics, three dimensional quasi stationary and steady-state heat transfer analysis has been carried out. The laser heat source is assumed as a volumetric heat source with a gaussian heat distribution in a plane. Through the comparison of the results of analyses with those of experiments, the proper finite element model has been obtained. In addition, characteristics of the three-dimensional heat transfer and temperature distribution have been estimated by the finite element model. Finally, the minimum temperature at the center for cutting of the material has been estimated.

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Weldability of Dissimilar Metal Plates with YAG Laser (YAG 레이저에 의한 이종금속판재의 접합특성)

  • 이지환
    • Journal of Welding and Joining
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    • v.6 no.1
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    • pp.21-27
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    • 1988
  • This paper describes weldability of dissimilar metal plates with YAG laser for the use of a small-size electronic spring parts. Effects of welding conditions, combination of plates, thickness of upper plate are examined in relation to welding strength and microstructure of welded region. The obtained results are summarized as follows. Welding defects such as cavity and crack showed a tendency to easily occur in the case where 1) pulse duration is short, 2) laser power is high, 3) PBS plate with high thermal diffusivity is used for lower plate. Among these defects, the occurrence of cavity cased a drop of welding strength. This results from the reduction of welding area between upper and lower plates. In SK-5/SUS304 plates (thickness: 0.2/0.4mm/, welding strength was the highest in welding conditions: laser power is 30J/pulse, pulse duration 9ms, amount of defocus +2mm.

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Hot cracking characteristic of welding using Nd:YAG Laser beam (Nd:YAG 레이저용접에서 고온균열특성)

  • Ro, Kyoung-Bo;Yoo, Young-Tae;Oh, Yong-Seak;Shin, Ho-Jun;Kim, Ji-Hwan
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1159-1165
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    • 2003
  • The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. The major process parameters studied in the present laser welding experiment were position of focus, travel speed and laser power.

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Stencil cutting process by Nd:YAG laser II -Influence of process parameters on cutting characteristics of stencil- (Nd:YAG레이저를 이용한 스텐실 절단공정II -레이저의 공정변수가 스텐실 절단특성에 미치는 영향-)

  • Lee, Je-Hoon;Seo, Jung;Kim, Jung-Oh;Shin, Dong-Sik;Lee, Young-Moon
    • Laser Solutions
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    • v.4 no.2
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    • pp.47-57
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    • 2001
  • This study deals with the laser cutting of stencil for the PCB. The most important aim of this study is to determine optimal conditions which make good-qualify stencil in Nd:YAG laser cutting. We made an experiment according to various variables (power. type of mask. gas pressure, cutting speed, and pulse width) and analyzed the cutting characteristics (surface roughness, kerf width. dross) . Each variable has optimal value for good-qualify cut edge under fixed condition. And neural network after learning experimental data with a million time iteration could predict surface roughness of cut edge under arbitrary condition approximately.

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A study on the Second-Harmonic Generation(SBG) Conversion Characteristics of Nd:YAG Laser adopted Differential Superposition Mesh (중첩회로를 적용한 펄스형 Nd:YAG 레이저의 2차 SHG 변환효율에 관한 특성연구)

  • 김휘영;박두열
    • Proceedings of the IEEK Conference
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    • 2001.06e
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    • pp.215-218
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    • 2001
  • A pulsed Nd:YAG laser is used widely for materials processing and medical instrument. It's very important to control the laser energy density in those fields using a pulsed Nd:YAG laser. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this paper, the alternating charge and discharge system was designed to adjust a pulse repetition rate. This system is controlled by microprocessor and allows to frequence an expensive condenser for high frequency to cheap one for low frequency. In addtion, The microcontroller monitors the flow of cooling water, short circuit, and miss firing and so on. We designed Nd:YAG laser firmware with smart microcontroller, and want to explain general matters about the firmware from now.

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Application of 532 nm YAG-Laser Annealing to Crystallization of Amorphous Si Thin Films Deposited on Glass Substrates

  • Lee, Jong-Won;So, Byung-Soo;Chung, Ha-Seung;Hwang, Jin-Ha
    • Korean Journal of Materials Research
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    • v.18 no.3
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    • pp.113-116
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    • 2008
  • A 532 nm Nd-YAG laser was applied to crystallize amorphous Si thin films in order to evaluate the applicability of a Nd-YAG laser to low-temperature polycrystalline Si technology. The irradiation of a green laser was controlled during the crystallization of amorphous Si thin films deposited onto glass substrates in a sophisticated process. Raman spectroscopy and UV-Visible spectrophotometry were employed to quantify the degree of crystallization in the Si thin films in terms of its optical transmission and vibrational characteristics. The effectiveness of the Nd-YAG laser is suggested as a feasible alternative that is capable of crystallizing the amorphous Si thin films.

Optimum design and analysis of a diode side-primped Nd:YAG laser with a diffusive reflector (난반사체를 이용한 다이오드 횡여기 Nd:YAG 레이저의 최적화 설계 및 분석)

  • 이성만;윤미정;김선국;김현수;차병헌;문희종
    • Korean Journal of Optics and Photonics
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    • v.12 no.6
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    • pp.489-495
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    • 2001
  • We developed a design code for a diode side-pumped Nd:YAG laser with a diffusive reflector to investigate the optimum design conditions resulting in homogeneous absorption distribution and efficient laser output power. By including the thermal tensing effect in the calculation of the laser output power, the calculated output powers were in fairly good agreement with the experimental results within the stable resonator condition. The calculation method can be used effectively for a diode side-pumped Nd:YAG laser in choosing the optimum design parameters and in predicting the laser output power.

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Comparison of Welding Characteristics of Austenitic 304 Stainless Steel and SM45C Using a Continuous Wave Nd:YAG Laser (오스테나이트계 스테인리스강과 SM45C의 연속파형 Nd:YAG 레이저 용접특성비교)

  • 유영태;오용석;노경보;임기건
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.3
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    • pp.58-67
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    • 2003
  • Welding characteristics of austienite 304 stainless and SM45C using a continuous wave Nd:YAG laser n experimentally investigated Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much Inter than those involved in conventional welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameter such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar and plates, etc. The Nd:YAG laser welding process is one of the most advanced manufacturing technologies owing to its high speed and penetration. This paper describes the weld ability of SM45C carbon steel for machine structural use by Nd:YAG laser. The follow conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power.

An analysis of Cutting Characteristic of Multilayer FPCB using Nd:YAG UV Laser System (Nd:YAG UV 레이저를 이용한 연성회로 다층기판 절단특성에 대한 연구)

  • Choi, Kyung-Jin;Lee, Young-Hyun
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.3
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    • pp.9-17
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    • 2010
  • The FPCB is used for electronic products such as LCD display. The process of manufacturing FPCB includes a cutting process, in which each single FPCB is cut and separated from the panel where a series of FPCBs are arrayed. The most-widely used cutting method is the mechanical punching, which has the problem of creating burrs and cracks. In this paper, the cutting characteristics of the FPCB have been experimented using Nd:YAG DPSS UV laser as a way of solving this problem. To maximize the industrial application of this laser cutting process, test samples of the multilayered FPCB have been chosen as it is actually needed in industry. The cutting area of the FPCB has four different types of layer structure. First, to cut the test sample, the threshold laser cut-off fluence has been found. Various combinations of laser and process parameters have been made to supply the acquired laser cut-off fluence. The cutting characteristics in terms of the variation of the parameters are analyzed. The laser and process parameters are optimized, in order to maximize the cutting speed and to reach the best quality of the cutting area. The laser system for the process automation has been also developed.

CUTTING EFFICACY OF Er:YAG LASER AND CONVENTIONAL BUR IN DECIDUOUS AND PERMANENT TEETH (Er:YAG laser와 Conventional bur의 유치와 영구치 치아삭제효과 비교)

  • Park, In-Cheon;Lee, Chang-Seop;Lee, Nan-Young;Lee, Sang-Ho
    • Journal of the korean academy of Pediatric Dentistry
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    • v.30 no.2
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    • pp.272-285
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    • 2003
  • This study was conducted to observe the microscopic structures of cavities formed after ablation of primary teeth, permanent teeth, enamel and dentin in using a bur and cavities formed after ablation using laser and the following results were obtained after comparing the effects of ablation. Using a #330 bur and Er:YAG laser irradiated at 150 mJ, 200 mJ, 250 mJ and 300 mJ all at the frequency of 5 Hz, 1 mm enamel and dentin samples were ablated and the ablation time was measured. In order to measure the surfaces ablated, 5 each of primary teeth and permanent teeth were ablated using a #330 bur and Er:YAG laser at 150 mJ, 200 mJ, 250 mJ and 300 mJ for 1 sec and the cross section and vertical section were observed. The following results were obtained : 1. Cutting time of Er:YAG laser was longer than that of conventinal high-speed bur regardless of teeth type. 2. Cutting on enamel, Cutting time of conventional high-speed bur in deciduous teeth was longer than in permanent teeth(P<0.05). But Er:YAG laser was not showed any difference between the deciduous and permanent teeth(P>0.05). 3. Cutting on dentin, Cutting time of conventional high-speed bur in permanent teeth was longer than deciduous teeth. Er:YAG laser of 150 mJ, 5 Hz in permanent teeth was longer than in deciduous teeth(p<0.05). But laser of other power did not showed mean difference. 4. The cavity surface treated with the convetional high-speed bur revealed a relatively flat appearance, almost covered with a debris-like smear layer. Cavity wall showed striped appearance because of blade of bur. 5. The cavity surface treated by the Er:YAG laser system was irregular or rough surface with the absence charring, carbonization, or cracking of the dentin. In addition, there was an absence of a smear layer. Cavity floor was round and relatively smooth. According to these results, cutting time of Er:YAG laser was almostly same in permanent and deciduous teeth, but more effective in dentin than enamel. Cutting the sample, Er:YAG laser was needed more time than conventional bur. But SEM findings suggested that laser device produced favorable surface characteristic(i.e, no smear layer, irregular surface, cracking).

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