Nondestructive web thickness measurement of micro-drills with an integrated laser inspection system

作者：Chuang Shui Fa; Chen Yen Chung; Chang Wen Tung^*; Lin Ching Chih; Tarng Yeong Shin

来源：Nondestructive Testing And Evaluation, 2010, 25(3): 249-266.

DOI：10.1080/10589751003637077

• micro-drill
• web thickness
• web taper
• nondestructive measurement
• laser micro-gauge
• laser confocal displacement meter

Nowadays, the electric and semiconductor industries use numerous micro-drills to machine micro-holes in printed circuit boards. The measurement of web thickness of micro-drills, a key parameter of micro-drill geometry influencing drill rigidity and chip-removal ability, is quite important to ensure quality control. Traditionally, inefficiently destructive measuring method is adopted by inspectors. To improve quality and efficiency of the web thickness measuring tasks, a nondestructive measuring method is required. In this paper, based on the laser micro-gauge (LMG) and laser confocal displacement meter (LCDM) techniques, a nondestructive measuring principle of web thickness of micro-drills is introduced. An integrated laser inspection system, mainly consisting of a LMG, a LCDM and a two-axis-driven micro-drill fixture device, was developed. Experiments meant to inspect web thickness of micro-drill samples with a nominal diameter of 0.25mm were conducted to test the feasibility of the developed laser inspection system. The experimental results showed that the web thickness measurement could achieve an estimated repeatability of +/- 1.6m and a worst repeatability of +/- 7.5m. The developed laser inspection system, combined with the nondestructive measuring principle, was able to undertake the web thickness measuring tasks for certain micro-drills.

• 出版日期2010