Experimental study on micro-drills wear during high speed of drilling IC substrate

Circuit World ◽  
2014 ◽  
Vol 40 (2) ◽  
pp. 61-70 ◽  
Author(s):  
Linfang Wang ◽  
Lijuan Zheng ◽  
Cheng yong Wang ◽  
Shan Li ◽  
Yuexian Song ◽  
...  
Keyword(s):  
High Speed ◽  
Base Material ◽  
Circuit Board ◽  
Drilling Process ◽  
Wall Roughness ◽  
Location Accuracy ◽  
Content Type ◽  
Drill Diameter ◽  
Micro Holes ◽  
Micro Drill

Purpose – Compared with the traditional printed circuit board (PCB) drilling process, the technology of drilling IC substrate is facing more problems, such as much smaller hole diameter, more intensive hole space, thinner sheet and more complicated materials are drilled in process. Moreover, the base material of IC substrate is different from traditional PCB, more kinds of fillers added in IC substrate which make the drill worn seriously during drilling process. Micro-drills wear and micro holes quality are the most important questions when drilling IC substrate so far. Wear morphology of micro-drill, holes wall roughness and hole location accuracy are researched in this paper. The influence factors of micro-drills wear and micro holes quality are also studied in this drilling process. The paper aims to discuss these issues. Design/methodology/approach – Two drills with same structure and different diameter are used to drill different stacks of IC substrate and drill different holes in this paper. There are four experiments made and the drilling parameters including spindle speed (n), feed rate (vf) and retraction speed (vr) are recommended by drill manufacturing company. Wear morphologies of drill are observed, holes wall roughness (Rmax) and holes location accuracy (Cpk) are measured in this paper. Analyzing the main factors influence on drill wear, holes wall roughness and holes location accuracy through these experiments. Findings – The micro-drills of IC substrate wear more severely compared with other material of PCB through the experimental results in this paper. Drill diameter has influence on micro-drill wear when drilling IC substrate, the smaller of drill is, the more severely of micro-drill wears. Drill diameter affect the holes wall roughness too, the holes wall roughness of larger holes is better than smaller one in a certain range. The drilled holes number also has influence on micro-drills wear, holes wall roughness and holes location accuracy. The more drilled holes, the seriously of micro-drills wear, and the worn drill would destroy the hole quality. Therefore, the more drilled holes lead the bad holes wall roughness and holes location accuracy in this paper. In addition, stacks of IC substrate affect much on the holes location accuracy, the more stacks, the worse holes location accuracy. Originality/value – Chinese Mainland is obviously lagging behind in technology and manufacturer of IC substrate which is incompatible with the nation circumstances. There is few research of drilling IC substrate in China and research data are lacking so far. It is most necessary to improve the technology level of drilling IC substrate in China. In order to reduce the wear of micro-drills and improve the quality of micro-holes, many experimental tests about drilling IC substrate are researched in this paper.

Characterization of drill bit breakage in PCB drilling process based on high-speed video analysis

Circuit World ◽  
2017 ◽  
Vol 43 (3) ◽  
pp. 89-96 ◽  
Author(s):  
Hongyan Shi ◽  
Xiaoke Lin ◽  
Yun Wang
Keyword(s):  
Video Analysis ◽  
High Speed ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Drilling Process ◽  
Drill Bit ◽  
Content Type ◽  
High Speed Video ◽  
Micro Drill

Purpose The purposes of this paper are to study the characterization of drill bit breakage in printed circuit board (PCB) drilling process based on high-speed video analysis and to provide an important reference for micro drill bit breakage prediction. Design/methodology/approach Based on PCB drilling experiment, the high-speed camera was used to observe the micro drill breakage process and the chip removal process. The variation of chip in the drilling process was studied and one of the key reasons for the drill bit breakage was analysed. Finally, the swing angles’ feature during the breakage process of the micro drill was analysed and researched with the image processing tools of MATLAB. Findings The micro drill was prone to breakage mainly because of the blocked chips. The breakage process of the micro drill can be divided into the stage of stable chips evacuation, the stage of blocked chips and the stage of drill bit breakage. The radians of swing angles were basically in the range of ±0.01 when the drilling possess is normal. But when the radians of swing angles considerably exceeded the range of ±0.01, the micro drill bit may be fractured. Originality/value This paper presented the method to study the characterization of drill bit breakage in the PCB drilling process by using high-speed video analysis technology. Meanwhile, an effective suggestion about monitoring the radians of swing angles to predict the breakage of micro drill bit was also provided.

Preparation and performances of coated and aluminous entry boards with water-soluble resins for PCB drilling

Circuit World ◽  
2016 ◽  
Vol 42 (4) ◽  
pp. 153-161 ◽  
Author(s):  
Hu Zhou ◽  
Bin Yu ◽  
Ning Li ◽  
Jie Zhou ◽  
Xiaoyang Luo ◽  
...  
Keyword(s):  
Production Efficiency ◽  
Heat Dissipation ◽  
Water Solubility ◽  
Water Soluble ◽  
Circuit Board ◽  
Drilling Process ◽  
Drill Bit ◽  
Scanning Calorimetry ◽  
Location Accuracy ◽  
Content Type

Purpose This paper aims to provide a new drilling entry board for printed circuit board (PCB) process, superior in heat dissipation, lubrication, water solubility and hole location accuracy, achieving an excellent drilling process. Design/methodology/approach Using a mixture of polyethylene glycol (PEG) and water-soluble adhesives as hydrosoluble, endothermic and lubricant resins and aluminum foils as baseplates, a series of coated and aluminous entry boards (CABs) for PCB drilling was successfully prepared. The surface appearance of the entry boards was observed clearly by scanning electron microscopy (SEM). The endothermic and lubricant effects of the resins applied on the CABs was characterized by differential scanning calorimetry (DSC) and their water solubility was tested in the normal-temperature water (25°C). Moreover, the CABs’ good drilling properties were tested when they were used for PCB drilling. Findings The SEM analysis showed that the surfaces of the resin layers coated on the CABs whose coating thicknesses were less than 80 μm were smoother and flatter, which could improve hole location accuracy and reduce drill breakage ratio. By virtue of DSC, the endothermic and lubricant effects of the CABs were proven. The fusion of PEG in the resin layers could absorb the heat produced by drilling, restrain the temperature of the drill bit and hole rising and lubricate the drill bit efficiently when a hole was being drilled, which could achieve high-quality holes with good production efficiency. The water-soluble test showed that the prepared CABs had excellent water solubility at normal temperature, enabling the resin left on the hole walls and in the flute of the drill bit to be washed away easily and thereby improving the drilling efficiency and quality. The drilling tests showed that the increase in the thickness of the CABs’ coating could improve the hole location accuracy and alleviate the bit wear. In addition, the suitable coating thickness could ensure the firm adhering of the resin coating the aluminum foil, effectively avoid drill intertwist and prevent the resin debris from blocking the drilled holes on the surface of the entry board, which could hinder chip removal, resulting in poor hole wall quality and drill breakage. Originality/value This paper has a remarkably high industrial practicality in the PCB manufacture process.

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.

Investigation of chip formation and burr control in PCB fixture hole

Circuit World ◽  
2015 ◽  
Vol 41 (2) ◽  
pp. 61-69 ◽  
Author(s):  
Lixin Huang
Keyword(s):  
High Speed ◽  
Fem Simulation ◽  
Circuit Board ◽  
Hole Drilling ◽  
High Speed Photography ◽  
Drilling Process ◽  
Feed Speed ◽  
Content Type ◽  
Helical Angle ◽  
Exit Burr

Purpose – This paper aims to analyze their generation mechanism and factors influencing burr generation. The final goal is to use appropriate drill design and drilling process to control the generation of burrs. Design/methodology/approach – The mechanism of burr generation was studied through finite element method (FEM) simulation and drilling experiments. High-speed photography technology and scanning electron microscope (SEM) were used in this study. Findings – High-speed drilling burr is a printed circuit board (PCB) copper foil burr. Within a certain range, the feed speed and burr height is in positive correlation, and decrease in the feeding speed will favor the exit burr. Drill angle influences burr and chisel edge affect significantly, followed by the point angle, and helical angle has little effect. From the perspective of reducing the burr, a smaller chisel edge and smaller point angle should be chosen. Grinding chisel edge is another choice to decrease the burr but also ensures the blade strength. Originality/value – This paper investigates the mechanism of burr generation of PCB fixture hole drilling. The process of burr generation was captured by high-speed camera. The controlling methods of burr generation were illustrated at the end.

Effect of Rapid-Feed Step-Drilling Cycle and Super-High-Speed Spindle for High-Speed Micro Drilling in Printed Wiring Boards

2010 ◽  
Vol 447-448 ◽  
pp. 836-840 ◽  
Author(s):  
Eiichi Aoyama ◽  
Toshiki Hirogaki ◽  
Keiji Ogawa ◽  
Satoshi Nojiri ◽  
Yutaka Takeda
Keyword(s):  
High Speed ◽  
Drilling Process ◽  
Printed Wiring Boards ◽  
Step Method ◽  
Processing Efficiency ◽  
High Productivity ◽  
Micro Holes ◽  
Drilling Quality ◽  
Micro Drilling ◽  
Drilling Conditions

A drilling technique using micro-drills of 0.2 mm or less in diameter and a super-high-speed spindle of 160000 rpm or more has been developed for drilling ultra-micro holes in printed wiring boards (PWBs). The drilling process requires higher reliability and quality to maintain the reliability of the electrical connection between circuit layers. On the other hand, higher processing efficiency is also required in PWBs manufacturing. To maintain high productivity, drilling is normally performed using a non-step method, but heat damage called B-RING occurs around the drilled holes with this method. To solve these problems without the loss of processing efficiency, we applied the rapid-feed step-drilling cycle method. We investigated the B-RING for drilling quality and evaluated the drilling time for processing efficiency under various drilling conditions. We found that using a rapid-feed step-drilling cycle with an appropriate number of steps and feed rates ensures a higher level of hole quality and processing efficiency compared with the conventional non-step drilling.

Advanced utilization of 3D digital image correlation for thermal and impact reliabilities of electronics components

2021 ◽  
Vol 38 (1) ◽  
pp. 14-22
Author(s):  
Jae B. Kwak ◽  
Soonwan Chung
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Speckle Pattern ◽  
Free Fall ◽  
Image Correlation ◽  
Circuit Board ◽  
Electronic Packages ◽  
Impact Event ◽  
Content Type

Purpose This paper aims to present an adaptation of digital image correlation (DIC) to the electronics industry for reliability assessment of electronic packages. Two case studies are presented: one for warpage measurement of a micro-electro-mechanical system (MEMS) package under different temperature conditions and the other for the measurement of transient displacements on the surface of a printed circuit board (PCB) assembly under free-fall drop conditions, which is for explaining the typical camera setup requirement and comparing among different boundary conditions by fastening methods of PCB. Design/methodology/approach DIC warpage measurements on a small device, such as a MEMS package, require a special speckle pattern. A new method for the creation of speckle patterns was developed using carbon coating and aluminum evaporative deposition. To measure the transient response on the surface of a PCB during a free-fall impact event, three-dimensional (3D) DIC was integrated with synchronized stereo-high speed cameras. This approach enables the measurement of full-field displacement on the PCB surface during a free-fall impact event, contrary to the localized information that is obtained by the conventional strain gage and accelerometer method. Findings The authors suggest the proposed patterning method to the small-sized microelectronics packages for DIC measurements. More generally, the idea is to have a thin layer of the dark or bright color of the background and then apply the white or black colored pattern, respectively, so that the surface has high contrast. Also, to achieve a proper size of speckles, this paper does not want to expose the measuring objects to high temperatures or pressures during the sample preparation stage. Of course, it seems a complicated process to use aluminum evaporator, carbon coater and electroformed mesh. However, the authors intend to share one of the solutions to achieve a proper pattern on such small-sized electronic packages. Originality/value 3D DIC technique can be successfully implemented for the measurement of micro-scale deformations in small packages (such as MEMS) and for the analysis of dynamic deformation of complex PCB.

Influence of Pulsed-DC Power Frequency on Mechanical Properties and High Speed Drilling Application of a-C:H:Zr-x Coatings

2011 ◽  
Vol 328-330 ◽  
pp. 861-867
Author(s):  
Wen Hsien Kao ◽  
Yan Liang Su ◽  
Sun Hui Yao ◽  
S.H. Liu
Keyword(s):  
High Speed ◽  
Printed Circuit Board ◽  
Deposition Process ◽  
Circuit Board ◽  
Hole Drilling ◽  
Closed Field ◽  
Machining Performance ◽  
Dc Power ◽  
Pulsed Dc ◽  
Micro Drill

The a-C:H:Zr-x coatings are deposited on micro-drills using a closed field unbalanced magnetron (CFUBM) sputtering system with pulsed-DC power frequencies in the range 30 kHz to 110 kHz (the x in the term a-C:H:Zr-x is the frequency varied in the deposition process). The hardness of the various coatings is systematically explored. Additionally, the machining performance of the coated micro-drills is investigated by conducting high-speed through-hole drilling tests utilizing Printed Circuit Board (PCB) specimens. The experimental results reveal that the a-C:H:Zr-70 coating has the highest hardness (42 GPa), while the a-C:H:Zr-110 coating has the lowest hardness (26 GPa). In addition, it is shown that the a-C:H:Zr-70 coating increases the life of the micro-drill by a factor of three compared to that of an uncoated micro-drill.

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.

Cryogenic auxiliary drilling of printed circuit boards

Circuit World ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 279-286
Author(s):  
Dantian Lin ◽  
Chengyong Wang ◽  
Lianyu Fu ◽  
Yong Ke ◽  
Yuxing He ◽  
...  
Keyword(s):  
Tool Wear ◽  
Chip Morphology ◽  
Drilling Process ◽  
Wall Roughness ◽  
Cold Air ◽  
Content Type ◽  
Printed Circuit ◽  
Hole Wall ◽  
Capacity Current ◽  
Chip Removal

Purpose Large capacity current carrier printed circuit board (PCB) imposes strict control requirements on the hole wall roughness. The key factors are chip removal, drilling temperature and tool wear. This paper aims to find out a cryogenic drilling process to control the chip removal, chip morphology, tool wear and finally reduce the hole wall roughness. Design/methodology/approach The chip removal process, chip morphology, tool wear and hole wall roughness of glass fiber epoxy resin copper clad laminate (FR-4) drilling were observed and analyzed. The influence of cold air on the chip removal process, chip morphology, tool wear and hole wall roughness was also investigated. An optimization process of cold air auxiliary drilling was proposed to control the hole wall roughness of FR-4. Findings The results showed that the discharge time of copper foil chips with obvious characteristics can be used as the evaluation criterion for the smoothness of chip removal. The cold air can promote chip removal and reduce tool wear. In addition, the chip removal and cooling performance will be the best when using −4.7 °C cold air with the injection angle consisted with the angle of helical flute of the drill. The hole wall roughness of FR-4 could be controlled by drilling with −4.7°C cold air. Originality/value This paper was the first study of the effect of three kinds of cold air on PCB drilling. This provided a reference for the possibility that the cryogenic drilling methods apply to PCB drilling. A new cold air auxiliary drilling process was developed for large capacity current carrier FR-4 manufacturing.

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