Title page for etd-0028116-211556


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URN etd-0028116-211556
Author Ching-Hu Hsu
Author's Email Address No Public.
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Department Mechanical and Electro-Mechanical Engineering
Year 2015
Semester 1
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Study of laser cutting of Sapphire
Date of Defense 2016-01-27
Page Count 70
Keyword
  • laser cutter
  • trepan
  • laser scanner
  • fiber laser
  • laser maching
  • laser scribing
  • laser dicing
  • sapphire
  • infrared laser
  • ultraviolet laser
  • Abstract In this thesis, we study laser machining of sapphire and related issues. In order to achieve the industry’s general standard so this study focuses on sapphire processing optimum process parameters. There are two main processing needed, laser scribing for splitting and laser dicing. Laser scribing for splitting needs a cut depth of 1/3 the thickness of sapphire, and the finished surface can’t have chipping (< 30 μm), random crack or closet breaking. In addition, the processing time must be fast and stable. Therefore, this thesis proposes three different experimental dicing and processing parameters. First, experiment applies simple optical system (direct beam) with “optical trepan” and XY-stage with laser source of ultraviolet. The parameters of laser frequency at 25 kHz, laser power of 3 watt and once round rip cutting with speed 5 mm/s can achieve depth of 1/3 the thickness. Using optical improvements, installation “optical trepan” in optical path to make small circle around area circle can improve the speed of XY-stage. Then laser dicing can be achieved (the gap between the surface and back side is about 40 μm). Second experiment is using ultraviolet laser source. But in the optical system, we install “Laser Scanner” (Galvo Head) with high cutting speed characteristic and high freedom of laser machining. Laser frequency of 25 kHz, laser power of 3 watt and 15 times round rip cutting with speed 100 mm/s can achieve depth of 1/3 the thickness. In high speed and high freedom of laser machining processing, “Repetition rate of machining” is more important. And the best repetition rate in scanner is 80%. Finally, to completely cut sapphire, we use a high power infrared fiber laser (150 watt) as a processing source. Installation laser cutter and coaxial blowing with different type cooling gas can improve the IR laser caused thermal effects. The best cooling gas is nitrogen (9 kgf/cm^2), which can isolate sapphire and oxygen interacting. Thus the thermal affected region can be less than 20 μm.
    Advisory Committee
  • Wang, Yu-Jen - chair
  • C. L. Chiu - co-chair
  • Cheng-Tang Pan - advisor
  • Files
  • etd-0028116-211556.pdf
  • Indicate in-campus at 99 year and off-campus access at 99 year.
    Date of Submission 2016-01-29

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