Study of micro-hole formation based on laser pre-drilling and magnetic assisted laser drilling

• Main Authors: Nai-yu Wang, 王乃右
• Other Authors: Chia-Lung Kuo
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/15677954167801357810

碩士 === 雲林科技大學 === 機械工程系碩士班 === 98 === In recent years, laser drilling has been an important role in industrial such as PCB, Solar Cell production and Ceramics applications. However, it is a still challenging task to drill on some materials such as aluminum and copper. More over, the high-reflectivity rate materials may cause decreasing on laser drilling rate. On the other hand, longer laser drilling time not only lead to wide and shallow hole, but also defect large hot area zone and intense recast layer on the side wall of the hole. In this study we create a novel laser drilling process using a Q-switched Nd:YAG laser with second harmonic 532nm, 8 ns pulse width and 0.255 J laser energy was used to generate plasma which allowed to expand across variable magnetic (electromagnetic) within 0.1 – 0.5 T, CCD video was used to visualize and record the activities in the focal region. The use of magnetic force was proposed to control the plasma flow direction and drilling rate of aluminum material, and a mathematical model was developed to investigate the effects of magnetic force (Lorentz force) on the plasma confinement and hole formation. The result demonstrate that penetrate a thorough hole of 0.6mm Aluminum can be reduced from 55 seconds to 10 seconds, achieved a high depth-to-width ratio hole, recast layer on hole side wall can also be eliminated. The study also focus on hybrid laser assisted mechanical micro-drilling (LAMD) process for a hard-to-machine material, using Nd:YAG 1064nm laser form an initial hole on SUS304, the initial hole serves as the guiding hole in order to assist the micro-drill penetrate through 1mm thick SUS304 via. In particular, it is found that the micro-drill abrasion rate can be reduced over 90%. Further more, hole diameter inaccuracy can narrowed down by 28%. Over all, the results shows LAMD process can improve hole formation quality, hole roundness, and also extending micro-drill tool life. Last but not least, the hot affect zone around the hole has been significantly reduced.