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

Circuit World ◽  
2020 ◽  
Vol 46 (4) ◽  
pp. 221-228
Author(s):  
Zhiyuan Li ◽  
Lijuan Zheng ◽  
Chengyong Wang ◽  
Xin Huang ◽  
Jiechi Xie
Keyword(s):  
Formation Mechanism ◽  
Thrust Force ◽  
Circuit Board ◽  
Hole Drilling ◽  
Hole Quality ◽  
Content Type ◽  
Burr Height ◽  
Printed Circuit ◽  
Flexible Printed Circuit ◽  
Micro Hole

Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.

The entry drilling process of flexible printed circuit board and its influence on hole quality

Circuit World ◽  
2015 ◽  
Vol 41 (4) ◽  
pp. 147-153 ◽  
Author(s):  
Lijuan Zheng ◽  
Chengyong Wang ◽  
Xin Zhang ◽  
Yuexian Song ◽  
Lunqiang Zhang ◽  
...  
Keyword(s):  
Printed Circuit Board ◽  
Circuit Board ◽  
Drilling Process ◽  
Hole Quality ◽  
Location Accuracy ◽  
Content Type ◽  
Printed Circuit ◽  
Flexible Printed Circuit ◽  
Micro Drilling ◽  
Micro Hole

Purpose – The purpose of this study is to present the entry drilling process of flexible printed circuit board (FPCs) and its influence on hole quality, especially hole location accuracy. Compared with the traditional PCB drilling process, the technology of drilling FPCs is facing more problems, such as hole location accuracy, smear on the hole wall surface, burned hole wall surface, etc. Moreover, the materials of FPCs are quite different from the rigid printed circuit boards (RPCs). FPCs no longer contain glass fiber cloths to reinforce resin, resulting in flexibility. Micro-hole quality is the most important issue in FPC drilling. Suggestions were given to obtain higher hole qualities and higher FPC reliability. Design/methodology/approach – The entry drilling process of FPC with different kind of entry boards was observed by a high-speed camera. The hole qualities of FPC micro-drilling, especially hole location accuracy and hole entrance quality, were measured. The relationship between entry boards and hole quality was analyzed. Findings – Significant sliding occurred when drilling FPC with using no-entry board or pure aluminum plate entry board. On the contrary, no significant sliding occurred when using LC-110 or resin-coated aluminum foil (MVC) entry boards. The type, thickness and use-pattern of entry boards influenced hole location accuracy of FPCs seriously. In addition, entry board also influenced the micro-hole entrance quality and micro-hole diameter. The entrance quality of drilling FPC with LC-110 entry board was the best. The diameter variation of drilling FPC with MVC entry board was the smallest. The hole location accuracy decreased as the thickness of entry board increased. Thus, the best use-pattern of entry board was putting a LC-110 under MVC entry board, resulting in best entrance quality and hole location accuracy. Originality/value – The technology and manufacturing of FPCs in China are obviously behind. Research of FPCs micro-drilling and research data are lacking so far. Thus, it is most necessary to improve the technology level of FPCs micro-drilling in China. Researches on hole quality, especially hole location accuracy of FPCs drilling, were performed in this paper. Suggestions were given to obtain higher hole quality of FPCs.

The tool-wear characteristics of flexible printed circuit board micro-drilling and its influence on micro-hole quality

Circuit World ◽  
2016 ◽  
Vol 42 (4) ◽  
pp. 162-169 ◽  
Author(s):  
Lijuan Zheng ◽  
Chengyong Wang ◽  
Xin Zhang ◽  
Xin Huang ◽  
Yuexian Song ◽  
...  
Keyword(s):  
Tool Wear ◽  
Circuit Board ◽  
Hole Quality ◽  
Content Type ◽  
Wear Characteristics ◽  
Printed Circuit ◽  
Micro Holes ◽  
Micro Drilling ◽  
Micro Hole

Purpose Micro-holes are drilled and plated in flexible printed circuit boards (FPCs) for connecting circuits from different layers. More holes, with diameters smaller than 0.3 mm, are required to be drilled in smaller areas with flexible circuits’ miniaturization. The micro-hole quality of micro-drilling is one of the biggest issues of the flexible circuit manufacturers’ production. However, it is not easy to control the quality of micro-holes. The purpose of this study was to conduct research on the tool wear characteristics of FPC drilling process and its influence on micro-hole quality to improve the micro-hole quality of FPC. Design/methodology/approach The tool-wear characteristics of micro-drills after FPC drilling were observed. The influence of spindle speed, feed rate, number of drilled holes and entry board materials on tool-wear was analyzed. The hole qualities of FPC micro-drilling were measured and observed. The relationship between tool-wear and hole quality was analyzed. Findings The result showed that the tool-wear characteristics of FPC micro-drilling was similar to the tool-wear characteristics of rigid printed circuit board (RPC) micro-drilling. Abrasive wear occurred on both the main cutting edges and the chisel edges of micro-drills, even though there was no glass fiber reinforcing the cloth inside FPC. Resin adhesion was observed on the chisel edge. The influence of feed and number of drilled holes on tool-wear was significant. Tool-wear significantly influences the hole quality of FPC. Tool-wear will largely decrease the hole position accuracy of FPC micro-holes. Tool-wear will increase the thickness of PI nail heads and the height of exit burrs. Fracture was the main difference between tool wear of FPC and RPC micro-drilling. Resin adhesion of RPC was much more severe than FPC micro-drilling. Increasing the spindle speed properly may improve tool life and hole quality. Originality/value The technology and manufacturing of FPC has been little investigated. Research on micro-drilling FPC and research data is lacking so far. The micro-hole quality directly affects the reliability of FPC. Thus, improving the micro-hole quality of FPC is very important.

Influential mechanism of printed circuit board properties on micro hole drilling temperature

Circuit World ◽  
2018 ◽  
Vol 44 (3) ◽  
pp. 125-131
Author(s):  
Hongyan Shi ◽  
Xiaoke Lin ◽  
Qiuxin Yan ◽  
Xiong Liang
Keyword(s):  
Temperature Measurement ◽  
Circuit Board ◽  
Hole Drilling ◽  
Content Type ◽  
Printed Circuit ◽  
Influence Mechanism ◽  
Drilling Temperature ◽  
Micro Drilling ◽  
Micro Hole ◽  
Infrared Temperature Measurement

Purpose The purpose of this paper was to study the influence of properties of printed circuit boards (PCBs) on the temperature during micro drilling and obtain the influential mechanism of PCBs based on temperature measurement. Design/methodology/approach Experiments were carried out to study the influence mechanism of PCB properties on micro hole drilling temperature under high spindle speed. The temperature measurement platform was applied, then the influence of components ratio of PCBs on the temperature of micro-drilling was analyzed by using comparative analysis method. The mass ratio of each kind of material in the PCB was defined as four levels and the influence mechanism of properties of PCBs based on temperature measurement was summarized. Findings Average filler and lower resin would have a positive impact on micro hole drilling temperature, and the smaller filler size and the even distribution would make it better. Originality/value An infrared temperature measurement platform was applied and influential mechanism of PCB properties on temperature was analyzed, which could provide the reference value on the optimization of temperature during micro drilling.

Experimental Study on Cutting Force of High-Speed Micro-Drilling Flexible Printed Circuit Board

2012 ◽  
Vol 723 ◽  
pp. 401-406 ◽  
Author(s):  
Xin Zhang ◽  
Cheng Yong Wang ◽  
Li Juan Zheng ◽  
Lin Fang Wang ◽  
Yue Xian Song
Keyword(s):  
Cutting Force ◽  
High Speed ◽  
Printed Circuit Board ◽  
Thrust Force ◽  
Circuit Board ◽  
Feed Speed ◽  
Printed Circuit ◽  
Flexible Printed Circuit ◽  
Micro Drilling ◽  
Exit Burr

Cutting force is one of the most important parameters in the drilling process of FPC (Flexible printed circuit board). It has a directly affect on the micro-drills’ life and the micro-holes quality. It causes the FPC delamination, pulling of the plastic, the burr of exit hole and other processing defects. In this paper, some experimental investigations of cutting force of high speed micro-drilling are carried out to improve the drilling quality of FPC. The results indicate that the drilling parameters(spindle speed, feed speed and drill-bit diameter) have significant influence on micro-drilling thrust force. The thrust force of drill copper foil is larger than the thrust force of drill adhesiver layer and the thrust force of drill PI layer is the smallest. The larger the thrust force is, the bigger the exit burr is.

The influence of properties of printed circuit board resin and filler on drilling force

Circuit World ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 165-170
Author(s):  
Hongyan Shi ◽  
Xiaoke Lin ◽  
Qiuxin Yan ◽  
JiaNan Zhang
Keyword(s):  
Measurement System ◽  
Printed Circuit Board ◽  
Force Measurement ◽  
Circuit Board ◽  
Hole Drilling ◽  
Drilling Force ◽  
Content Type ◽  
Printed Circuit ◽  
Micro Drilling ◽  
Force Measurement System

Purpose The purpose of this paper is to study and obtain the influence of resin and filler properties of printed circuit board (PCB) on the drilling force during micro drilling. Design/methodology/approach Experiments were carried out to study the influence of PCB on micro-hole drilling force under high spindle speed. A drilling force measurement system was applied, and then, the influence of resin and filler properties of PCBs on the force was analyzed. The proportion of resin and filler in the PCB was defined as four levels, and the influence of PCBs based on the drilling force measurement was summarized. Findings The drilling force decreased with the decrease in the feed rate, and lower filler (16-30 per cent) and average resin (31-50 per cent) would have a positive impact on the drilling force. At the same time, the size of uniform and fine fillers would help to reduce the drilling force. Originality/value The drilling force measurement system was applied, and the influence of PCBs on force was analyzed, which could provide a reference value on the optimization of the drilling force during micro drilling.

Micro drilling quality of the Cu/BT laminate for IC substrate

Circuit World ◽  
2016 ◽  
Vol 42 (2) ◽  
pp. 55-62 ◽  
Author(s):  
Shan Li ◽  
Li Juan Zheng ◽  
Cheng Yong Wang ◽  
Bing Miao Liao ◽  
Lianyu Fu
Keyword(s):  
Integrated Circuit ◽  
Circuit Board ◽  
Drilling Process ◽  
Hole Quality ◽  
Drilling Force ◽  
Talcum Powder ◽  
Content Type ◽  
Micro Drilling ◽  
Micro Hole ◽  
Drilling Conditions

Purpose In an integrated circuit (IC) substrate, more fillers, including talcum powder and aluminium hydroxide, are added, which leads to much higher rigidity and hardness compared with a traditional printed circuit board. However, the micro drilling of IC substrates is harder. This paper aims to test the drilling process of IC substrates to improve the drilling process and the micro hole quality. Design/methodology/approach Substrate drilling by a micro drill with 0.11-mm diameter was used under several drilling conditions. The influence of drilling conditions on the drilling process was observed. Drilling forces, drill wear and micro hole quality were also studied. Findings The deformation circle around holes, hole location accuracy, bugle hole and burrs were the major defects of micro holes that were observed during the drilling of the substrate. Reducing the drilling force and drill wear was the effective way to improve hole quality. Originality/value The technology and manufacturing of IC substrates has been little investigated. Research data on drilling IC substrates is lacking. The micro hole quality directly affects the reliability of IC substrates. Thus, improving the drilling technology of IC substrates is very important.

Heat transfer and deformation analysis of flexible printed circuit board under thermal and flow effects

Circuit World ◽  
2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chong Hooi Lim ◽  
M.Z. Abdullah ◽  
I. Abdul Azid ◽  
C.Y. Khor ◽  
M.S. Abdul Aziz ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Printed Circuit Board ◽  
High Reliability ◽  
Circuit Board ◽  
Deformation Analysis ◽  
Content Type ◽  
Printed Circuit ◽  
Bga Packages ◽  
Flexible Printed Circuit ◽  
Flow Effects

Purpose The purpose of this study is to investigate heat transfer and deformation of flexible printed circuit board (FPCB) under thermal and flow effects by using fluid structure interaction. This study simulate the electronic cooling process when electronic devices are generating heat during operation at FPCB under force convection. Design/methodology/approach The thermal and flow effects on FPCB with attached ball grid array (BGA) packages have been investigated in the simulation. Effects of Reynolds number (Re), number of BGA packages attached, power supplied to the BGA packages and size of FPCB were studied. The responses in the present study are the deflection/length of FPCB (δ/L) and Nusselt number (Nu). Findings It is important to consider both thermal and flow effects at the same time for understanding the characteristic of FPCB attached with BGA under operating condition. Empirical correlation equations of Re, Prandtl number (Pr), δ/L and Nu have been established, in which the highest effect is of Re, followed by Pr and δ/L. The δ/L and Nu¯ were found to be significantly affected by most of the parametric factors. Practical implications This study provides a better understanding of the process control in FPCB assembly. Originality/value This study provides fundamental guidelines and references for the thermal coupling modelling to address reliability issues in FPCB design. It also increases the understanding of FPCB and BGA joint issues to achieve high reliability in microelectronic design.

Optimization of flexible printed circuit board’s cooling with air flow and thermal effects using response surface methodology

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chong Hooi Li ◽  
Mohd Zulkifly Abdullah ◽  
Ishak Abdul Aziz ◽  
Chu Yee Khor ◽  
Mohd Sharizal Abdul Aziz
Keyword(s):  
Nusselt Number ◽  
Response Surface ◽  
Thermal Effects ◽  
Thermal Power ◽  
Operating Conditions ◽  
Circuit Board ◽  
Content Type ◽  
Printed Circuit ◽  
Bga Packages ◽  
Flexible Printed Circuit

Purpose This study aims to investigate the interaction of independent variables [Reynolds number (Re), thermal power and the number of ball grid array (BGA) packages] and the relation of the variables with the responses [Nusselt number ((Nu) ¯ ), deflection/FPCB’s length (d/L) and von Mises stress]. The airflow and thermal effects were considered for optimizing the Re of various numbers of BGA packages with thermal power attached on flexible printed circuit board (FPCB) for optimum cooling performance with least deflection and stress by using the response surface method (RSM). Design/methodology/approach Flow and thermal effects on FPCB with heat source generated in the BGA packages have been examined in the simulation. The interactive relationship between factors (i.e. Re, thermal power and number of BGA packages) and responses (i.e. deflection over FPCB length ratio, stress and average Nusselt number) were analysed using analysis of variance. RSM was used to optimize the Re for the different number of BGA packages attached to the FPCB. Findings It is important to understand the behaviour of FPCB when exposed to both flow and thermal effects simultaneously under the operating conditions. Maximum d/L and von Misses stress were significantly affected by all parametric factors whilst (Nu)¯ is significantly affected by Re and thermal power. Optimized Re for 1–3 BGA packages with maximum thermal power applied has been identified as 21,364, 23,858 and 29,367, respectively. Practical implications This analysis offers a better interpretation of the parameter control in FPCB with optimized Re for the use of force convection electronic cooling. Optimal Re could be used as a reference in the thermal management aspect in designing the BGA package. Originality/value This research presents the parameters’ effects on the reliability and heat transfer in FPCB design. It also presents a method to optimize Re for the different number of BGA packages attached to increase the reliability in FPCB’s design.

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