The High-Speed Drilling Performance of PCB Micro-Drill with Different Geometry Design
| Autor: | Hsing-Wen Chen, 陳興文 |
|---|---|
| Rok vydání: | 2002 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 90 The high-speed micro-hole drilling is one of the major processes of printed circuit board(PCB) fabrication. The quality of the process is very important to gold-coated disposal and the others. In drilling, the micro-drill contacts with PCB directly resulting in cutting effect on it. Drill bit geometry design is an important factor for drilling efficiency. The parameters of drill bit geometry design are complex and correlated with each other. Due to small diameter and high aspect ratio, the strength and rigidity of micro-drill becomes weak. In this research, point angle, helix angle, web thickness and chisel edge angle are four important design parameters of the drill bit geometry. Using partial factor design of experiment and the method of variance analysis, one can obtain the interaction relationship among design parameters, drilling force, wear, and PCB hole position accuracy. For three-axis resultant force analysis, the point angle has the highest variance and its contribution is 65.32% here. Meanwhile, the interaction effect between point angle and helix angle is the most significant. The smaller point angle is and the bigger helix angle is, the better the result is. But when point angle is bigger, the smaller helix angle is the best choice. As for torsion analysis, the interaction between point angle and chisel edge angle is very obvious and their contribution is 31.54% here. When the point angle is smaller and chisel edge angle is bigger, the torsion is the smaller. But when point angle is bigger, the chisel edge angle is not significant. However, the chisel edge angle should be smaller in this situation. In factorial experiment and analysis of wear, when the web thickness and the chisel edge angle are designed to be smaller, wear rate will reduce. Although the contribution of the point angle is only 0.003174%, the interaction effect between point angle and web thickness is very obvious. In order to reduce wear rate, point angle should be designed bigger. As for the analysis of hole position accuracy, the contribution of the helix angle is the most significant. The bigger point angle is, the worse hole position accuracy is. The interaction effect between helix angle and chisel edge angle is more obvious than the others. The smaller helix angle is and the bigger chisel edge angle is, the better hole position accuracy is. The results can be utilized in the micro-drill geometry design and determination of geometry parameter designed in new type micro-drill. It takes least time and money to develop micro-drill. In addition, researcher in micro-drill geometry design can fit more levels to the obvious effective factors in the beginning of the drilling experiment. The interaction effect of factor and each other can be considered at the same time. They can improve drill efficiency and the high-speed drilling performance of PCB. Keywords: high-speed drilling, micro-drill, drill bit geometry design, interaction effect, drill force, wear, hole position accuracy |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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