Search results

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.

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.

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.

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.

The purpose of this paper is to present key points relating to the development of micro drill bits with high aspect ratios and to provide a solution for high aspect ratio hole drilling.

Based on the analysis of challenges in high aspect ratio hole drilling, key points for the development of micro drills bit with high aspect ratio are discussed. A design example of a micro drill bit with 0.3 mm diameter and a 7.2 mm flute length is presented. Experiments are conducted to verify the performance of the developed micro drill bit.

Helix angle, web thickness and flute land ratio are three key parameters that significantly influence the behaviour of micro drill bits with high aspect ratios. Large helix angle, web thickness and flute land ratio are beneficial in terms of improving the performance of high aspect ratio micro drill bits. Step drilling is essential to prevent drill breakage and to ensure smooth debris evacuation. Meanwhile, proper steps and drilling parameters are of great importance to complete high aspect ratio hole drilling.

The paper highlights key points relating to the development of micro drill bits with high aspect ratios that can provide a satisfactory solution for high aspect ratio micro drill bit design.

The purpose of this paper is to present a system for accurately measuring drilling force in the printed circuit board micro drilling process and to characterize the drilling force to provide a better understanding of the micro drilling process.

The drilling force measurement system was established first. Then the drilling force in printed circuit board micro drilling process was characterized experimentally. In particular, the drilling forces in drilling halogen‐free and lead‐free assembly compatible printed circuit boards and the drilling force characteristics in ultra small hole drilling were investigated.

A drilling force measurement system, with the key component of a KISTLER 9256C2 dynamometer, can accurately measure the drilling forces in the printed circuit board micro drilling process. The micro drilling process can be characterized by drilling force. Meanwhile, drilling force is very sensitive to drill breakage and drilling force can be utilized to detect drill breakage in the micro drilling process.

The paper presents a system for accurately measuring the drilling force. Drilling force provides fundamental information for the optimal design of micro drill bits. Drilling force can also characterize the micro drilling process, especially the ultra small hole micro drilling process.

This paper aims to investigate and document the effects of copper-clad laminate (CCL) inorganic filler on the hole performance in printed circuit boards drilling process.

Drilling of brittle laminates can result in hole cracking, layer-to-layer delamination and drill-bit wear and tool breakage. Adding large amount of fillers not only shortens the life of the drilling tool but also affects the drilling properties significantly regarding hole quality. This paper introduces the influence of filler content, type, hardness, particle size and the compounding method in the manufacture of the CCL on the drilling performance.

The filler content, filler type, hardness of filler, particle size of filler and the compounding method used for the filler have a great influence on the drilling properties of CCL. The higher the filler content, the larger the particle size and the more the hardness of the filler, the worse the drilling properties. The combination of hard particles like silica with softer particles can improve the drilling performance of CCL.

The paper describes what affects the drilling performance of CCL and how this knowledge can be used to design CCL with good drilling performance.

In the manufacturing process for making printed circuit boards (PCB) it is necessary to drill holes in the base copper clad laminate. This is a crucial step in the case of multi‐layer boards where the holes must be plated with copper to complete the electrical connection between the layers. Drilling is an expensive process as it requires the use of extremely sophisticated equipment. Most often this resides with a handful of companies; namely board shops and drill bit manufacturers. In recent years, with the evolution of high performance resins such as high glass transition (T_g) and decomposition temperature (T_d) as well as low dielectric constant (D_k) and the continued embracement of the use of phenolic cured resins compared to dicyandiamide (DICY), issues around drillability have increased. As a part of our efforts we compared the mechanical and thermo‐mechanical properties of three resins. Actual drilling studies were performed on three‐high, copper clad stacks made from these three resins at Megatool in California, in order to confirm our fundamental property correlations. Resin toughness was found to play a crucial role in the final PCB drillability.

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.

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.

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.

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.

A developmental project has been initiated to create a new type of glass fabric, whose fibers are to be uniformly distributed in the laminate so as to comply with the requirement of homogeneity. As a result, various types of glass fiber fabrics have successfully woven through the uniquely developed “MS process”, and it has been verified that each of the glass fabrics possesses the most suitable structure to attain uniform distribution in the laminates. The laminates, using the newly developed glass fabrics, have proved that the micro‐diameter drilling, that is laser drilling and mechanical drilling with 0.1mm diameter, can be performed very easily with less drill bit breakage, and produces uniform drill holes. It has also been proved that the laminates with the new glass fabrics reveal improved mechanical properties such as lower CTE, decreased warp and twist and better dimensional stability compared with conventional laminates of glass epoxy. Various styles of new glass fabric cover the wide range of thickness from 100 microns down to 27 microns.

The purpose of this paper is to present and describe a solution of aluminum substrate drilling.

The development of LED and printed circuit board with metal substrate are reviewed first. Then the challenges of drilling metal substrate, particularly the aluminum substrate, are described. To find the solution, coated micro drill bit with optimized helix angle is developed. The performance of developed micro drill bit is examined via drilling force investigation. Finally, the drilling tests are conducted to verify the solution of aluminum substrate drilling.

Coated drill bit is a very good choice to solve the problems of drilling burr and chip clogging in aluminum substrate drilling. The reason is that the drilling force can be obviously reduced by using a coated drill bit. The drill bit with medium helix angle is beneficial to prevent chip clogging. A satisfactory solution of aluminum substrate drilling can be achieved by applying coated drill bit with medium helix angle together with appropriate entry board.

The paper presents a satisfactory solution of aluminum substrate drilling. By employing the presented solution, the problems of drilling burr and chip clogging can be avoided in aluminum substrate drilling.

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

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.

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.

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.

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.

Today a large variety of printed circuit board (PCB) base materials exists on the market and new ones are added frequently. The base material suppliers, having good original equipment manufacturer (OEM) marketing, usually present the materials in an early development stage to the end customers. The customers, on the other hand, expect from their PCB suppliers that the materials are fully characterized and that qualification samples are available immediately. In many cases, the process recommendations given to the PCB manufacturers are very generic (“like FR4”), insufficient, or not practicable (“8 hours baking time”). However, optimized processing ensures the reliability of the finished PCBs, starting from general leadfree compatibility to CAF testing. This demonstrates the importance of thoroughly verified process parameters and of very specific process recommendations to minimize the number of costly and time‐consuming iterations, and to be able to meet the goal of submitting qualification samples and functional PCBs in minimum time. The purpose of this paper is to show the minimum required PCB processing recommendations, and why these have to be fixed by the material supplier before commercialization of a new base material.

The paper examines the base material suppliers' situation, customer expectations and reality and the PCB manufacturers' expectations.

The paper gives the reasons and consequences of early base material marketing.

The paper analyses today's PCB base materials market and shows the reasons and consequences of early base material marketing. Also, the minimum requirements by PCB fabricators concerning processing recommendations are given.