Development of Micro Drill Bit for Drilling Environment-Friendly PCBs

摘要

Currently environment-friendly PCBs (including lead-free assembly compatible PCB and halogen-free PCB) become popular in PCB industry to meet the requirements of environmental protection. Correspondingly, as a fundamental manufacturing process in PCB fabrication, mechanical drilling has to be innovated. A new type of drill bit is developed to provide solutions for drilling environment-friendly PCBs.Worldwide PCB and micro drill bit manufacturing industry are briefly reviewed first. Challenges of drilling environment-friendly PCBs are described and the objective of this study is covered. Then key design points including helix angle design, primary face angle design and helix groove shape optimization are presented. The influential mechanism of drill bit key parameters on its rigidity, strength, debris evacuation capability is investigated. Helix angle, helix groove shapes and primary face angle are optimized to ensure sufficient cutting edge strength and excellent wear-resistant capacity. Finally, experiments are conducted to verify the performances of micro drill bit with optimized parameters. Experimental results confirm that a micro drill bit with small helix angle and primary face angle as well as optimized helix groove shape is beneficial to drilling environment-friendly PCBs.