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Article
Publication date: 29 April 2014

Linfang Wang, Lijuan Zheng, Cheng yong Wang, Shan Li, Yuexian Song, Lunqiang Zhang and Peng Sun

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…

Abstract

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.

Details

Circuit World, vol. 40 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 10 September 2019

Dantian Lin, Chengyong Wang, Lianyu Fu, Yong Ke, Yuxing He, Gexian Fang, Junxiong Yao, Xin Huang and Lijuan Zheng

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…

88

Abstract

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.

Details

Circuit World, vol. 45 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 16 May 2008

Lianyu Fu and Fan Yang

To provide a solution for PCB drilling with strict requirements on hole wall quality.

Abstract

Purpose

To provide a solution for PCB drilling with strict requirements on hole wall quality.

Design/methodology/approach

The influential mechanism of key micro drill bit parameters on hole wall roughness is analyzed. A new type of micro drill bit is developed on the basis of theoretical analysis and experimental verifications.

Findings

The key factors in drill bit design which can enable superior hole wall quality are described. Experimental results show that very good hole wall quality is achieved by such newly developed drill bits. Meanwhile, the new drill bits show good performance in terms of wear‐resistance and hole registration accuracy. A solution for PCB drilling with strict requirements on hole wall quality is provided.

Originality/value

The paper highlights the influential mechanism of key parameters of micro drill bit design on the hole wall quality of PCBs. A new kind of micro drill bit which can achieve superior hole wall quality has been developed.

Details

Circuit World, vol. 34 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 1 April 1988

M. Feldin, C. Zevnik and I. Kovač

Outgassing of PTH PCBs at different stages of PCB production was studied with a modified IEC outgassing test, Draft June 1985, now included in IEC 326–2 Amendment No. 2, January…

Abstract

Outgassing of PTH PCBs at different stages of PCB production was studied with a modified IEC outgassing test, Draft June 1985, now included in IEC 326–2 Amendment No. 2, January 1988. Outgassing rate from single PTHs was quantitatively measured with a U‐tube manometer as a pressure of expanded steam escaped. Some technological parameters were taken into account and different comparisons were made: PCB production stage (drilling, copper and solder plating, reflowing) vs. outgassing rate, laminate thickness vs. outgassing rate. The contributions to outgassing of PTHs through PCB production, especially from copper and tin‐lead plating, are seen. On PCBs, drilled with different drills and soldered unpopulated on wave and drag soldering machines, outgassing faults were assessed. By multiple regression the relation between outgassing faults, hole wall roughness and plated copper thickness was calculated.

Details

Circuit World, vol. 15 no. 1
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 1 April 1986

C. Lea and F.H. Howie

The drilling and preparation of a hole in FR‐4 laminate prior to the deposition of electroless copper is considered in relation to the quality of soldering achieved on the…

Abstract

The drilling and preparation of a hole in FR‐4 laminate prior to the deposition of electroless copper is considered in relation to the quality of soldering achieved on the finished printed circuit board. Data pertaining to the drill speed, drill feed, and stack position are presented and the effect of drilling temperature is demonstrated. The variability of laminate is discussed in relation to outgassing during soldering. Finally the importance of the post‐drilling treatment of the holewall is shown. The relative effects of baking after drilling, ultrasonic cleaning and chemical treatments such as alkaline potassium permanganate are illustrated.

Details

Circuit World, vol. 13 no. 1
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 1 April 1985

H. Brösamle

Back taper drills, back taper drills with cylindrical tips and spade type drills were the three types available in the past for drilling multilayer boards in the diameter range of…

Abstract

Back taper drills, back taper drills with cylindrical tips and spade type drills were the three types available in the past for drilling multilayer boards in the diameter range of 0·8 to 1·1 mm. With packaging developments, drilling of smaller diameters, such as 0·4 mm, became necessary and care had to be taken to avoid drill breakage. The effects of board thickness, drill diameter and feed on drill breakage are analysed, followed by discussion of parameters affecting drilling accuracy and drill run‐out. The paper then deals with the effect of drill design on drill breakage, resin smear, nailheading and hole wall roughness. Results obtained using one back taper reference drill and seven other different spade type drill designs are analysed.

Details

Circuit World, vol. 12 no. 1
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 5 May 2015

Xiong Liang, Bing Li, Lianyu Fu, Xiaoyu Wu, Hongyan Shi, Taijiang Peng and Bin Xu

This paper aims to present the main factors affecting the mechanical drilling of the printed circuit board (PCB for short) micro-holes and method of micro-ultrasonic powder…

1042

Abstract

Purpose

This paper aims to present the main factors affecting the mechanical drilling of the printed circuit board (PCB for short) micro-holes and method of micro-ultrasonic powder molding (micro-UPM for short) by utilizing PCB micro-hole array.

Design/methodology/approach

To optimize the drilling process, the paper proposes the on-line monitoring methods for the drilling process including drilling force, drilling temperature, high-speed photography and vibration signals. Taking 0.10 and 0.15 mm micro-drilling as examples, the paper analyzes the drilling process of ultra-small micro-holes. Finally, by taking the PCBs with 0.10 and 0.15 mm micro-hole arrays as the micro-cavity inserts, utilizing ultra-high-molecule weight polyethylene powder with the average particle size of about 150 μm as raw material, two sizes of micro-cylinder array polymer parts are fabricated through micro-UPM process.

Findings

PCB micro-cavity inserts with micro-hole arrays fabricated by mechanical drilling has the advantages of low costs, high efficiency and good consistency. Taking 0.10 and 0.15 mm micro-drilling as examples, it is found that the both measured apertures are about 10.0 μm more than the diameter of the micro-drill bits on average. The average diameter of the micro-cylinders by micro-UPM process is smaller than that of the micro-hole with the same specification, while the value of the roughness of the cylinder surface is more than that of the hole-wall surface with the same specification.

Originality/value

This paper describes the challenges and the developments of mechanical drilling and by using PCB micro-cavity inserts with micro-hole arrays fabricated by mechanical drilling, two different micro-cylinder array polymer parts are successfully made and thus the application area of PCB micro-drilling is broadened.

Details

Circuit World, vol. 41 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 16 August 2013

Hu Zhou, Ruiping Xun, Qingquan Liu and Peng Wu

The purpose of this paper is to provide a new entry board for drilling holes on the PCBs, superior in heat removal effect, lubricating effect and hole locating effect in forming…

Abstract

Purpose

The purpose of this paper is to provide a new entry board for drilling holes on the PCBs, superior in heat removal effect, lubricating effect and hole locating effect in forming holes, resulting in an excellent process of forming holes with a high quality.

Design/methodology/approach

With the mixture of PEG, PEO and adhesive used as endothermic and lubricant resins and aluminium foils used as baseplates, a series of coated and aluminous entry boards (CABs) for PCB drilling were successfully prepared. Scanning electron microscopy (SEM) was employed to observe the surface appearance of the entry boards. The endothermic and lubricant effect of the resin applied on the CABs was characterized by differential scanning calorimetry (DSC) and polarizing microscope (POM). Moreover, the CABs' good drilling properties were tested when they were used for PCB drilling.

Findings

From the result of SEM analysis, it was found that compared to the common aluminium foil, the surfaces of the CABs were smoother and flatter, which could improve the hole location accuracy and reduce the drill breakage. By means of the DSC and POM, the endothermic and lubricant effect of the CABs was proved. The crystalline substances (PEG and PEO) in coated resin could absorb the heat of the drill bit from heat generation and lubricate it through the phase transition of they own when a hole was being made, which could give high‐quality holes with good production efficiency. The drilling tests showed that due to the endothermic and lubricant resins, the CABs were superior to the common aluminium foil, not only in hole location accuracy, but also in hole wall quality and protection of a drill bit.

Originality/value

This paper has a remarkably high industrial practicality in the PCB manufacture process.

Article
Publication date: 3 May 2016

Shan Li, Li Juan Zheng, Cheng Yong Wang, Bing Miao Liao and Lianyu Fu

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…

Abstract

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.

Details

Circuit World, vol. 42 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 18 November 2013

Xiaohu Zheng, Dapeng Dong, Lixin Huang, Xibin Wang and Ming Chen

– The paper aims to investigate tool wear mechanism and tool geometry optimization of drilling PCB fixture hole.

Abstract

Purpose

The paper aims to investigate tool wear mechanism and tool geometry optimization of drilling PCB fixture hole.

Design/methodology/approach

An experimental study was carried out to investigate the chip formation and tool wear mechanism of drilling PCB fixture holes. Two types of drill with different types of chip-split groove were used in this study. The performances of these two types of drill bots were evaluated by tool wear and the shapes of chips.

Findings

The chips of drilling fixture holes contain aluminum chips from the cover board, copper chips from the copper foil, discontinuous glass fiber and resin from the CFRP. Feed rate and drilling speed have a great influence on the chip morphology. Abrasive wear of the drill lip is the main reason of the fixture drill bit in drilling PCB, and micro-chipping is observed on the tool nose and chisel edge. The influence of distance between the chip-split groove and drill point center on the axial force and torque is not obvious.

Research limitations/implications

In this paper, hole wall roughness and drilling temperature were not analyzed in the optimization of drilling parameters. The future research work should consider them.

Originality/value

This paper investigated the mechanism of burr formation and tool wear in drilling of PCB fixture holes. Tool geometry was optimized by adding chip-split grooves.

Details

Circuit World, vol. 39 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

1 – 10 of 464