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Investigation of burr formation and its influence in micro-drilling hole of flexible printed circuit board

Zhiyuan Li (Guangdong University of Technology, Guangzhou, China and Delton Technology (Guzangzhou) Inc., Guangzhou, China)
Lijuan Zheng (Guangdong University of Technology, Guangzhou, China)
Chengyong Wang (Guangdong University of Technology, Guangzhou, China)
Xin Huang (Guangdong University of Technology, Guangzhou, China)
Jiechi Xie (Guangdong University of Technology, Guangzhou, China)

Circuit World

ISSN: 0305-6120

Article publication date: 30 June 2020

Issue publication date: 7 October 2020




The flexible printed circuit (FPC) board with the characteristic of light and thin strengthened confronted the growing miniaturization requirements of the electronic product and the popularity of wearable devices. The reliability of circuit could be influenced by the hole quality of FPC, such as burrs, which is one of the major problem in FPC.


In this paper, micro-drill with a diameter of 0.1 mm was used to drill the double-sided flexible copper clad laminate. The thrust force, the burr and tool wear were investigated. The influencing factors of the height of the burrs were studied. The relationship between the thrust force and the height of the burrs was also explored. Finally, the formation mechanism of burrs was analyzed.


The entrance burrs were usually less than the exit burrs. The burr height increased with the feed per rotation. The height of the burr increased with the increase of the thrust force for the plastic deformation of the copper foil was dominant. The abrasion of the drill gave rise to increase the height of burr. In micro-hole drilling, the growth of burrs can be suppressed effectively by reducing the clearance between the FPC and the backup plate. The thrust force would be controlled in a certain range to reduce the burr with specific drilling parameters. There existed a certain relationship of Gaussian distribution between the height of the burrs and the thrust force of FPC.


The reliability of the integrated circuit was directly affected by the burrs of the FPC. This research on the formation mechanism of FPC burrs and forecast of burr height provided a firm foundation for further work in the area of improvement of the micro-hole quality.



This research was funded by the National Natural Science Foundation of China (No. 51875110), Major Scientific Research Projects of Guangdong Province (Grant No.2014KZDXM030), Innovation and Better University Project of Education Department of Guangdong Province (Grant No.15ZK0208), Project for Pearl River New Star in Science and Technology (Grant No. 201806010175), Project for Science and Technology of Guangzhou (Grant No. 201802010024), Guangdong Province Applied Science and Technology R&D Special (Grant No.2016B090928002) and Characteristic innovation project of Guangdong Provincial Education Department (Grant No. 2015KTSCX028).


Li, Z., Zheng, L., Wang, C., Huang, X. and Xie, J. (2020), "Investigation of burr formation and its influence in micro-drilling hole of flexible printed circuit board", Circuit World, Vol. 46 No. 4, pp. 221-228.



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