• 한국정보통신설비학회:학술대회논문집
• /
• 2006.08a
• /
• pp.170-174
• /
• 2006

In this paper electromagnetic topology (EMT) is used to analyze the lumped components on printed circuit boards (PCBs). It is difficult to obtain desirable results about the electromagnetic coupling problems by using a numerical or an experimental method on complex systems. The EMT can be considered as a helpful method to the analysis of electromagnetic interference / electromagnetic compatibility (EMI/EMC) problems in the complex system. To verify the validity of this method, three types of the PCBs mounting a simple circuit are fabricated and experimented.

• Journal of Environmental Science International
• /
• v.24 no.2
• /
• pp.245-251
• /
• 2015

The main objective of this study is to recovery valuable metals with metal particle size distributions in waste cell phone PCBs(Printed Circuit Boards) by means of pulverization and nitric acid process. The particle size classifier also was evaluated by specific metal contents. The PCBs were pulverized by a fine pulverizer. The particle sizes were classified by 5 different sizes which were PcS1(0.2 mm below), PcS2(0.20~0.51 mm), PcS3(0.51~1.09 mm), PcS4(1.09~2.00 mm) and PcS5(2.00 mm above). Non-magnetic metals in the grinding particles were separated by a hand magnetic. And then, Cu, Co and Ni were separated by 3M nitric acid. Particle diameter of PCBs were 0.388~0.402 mm after the fine pulverizer. The sorting coefficient were 0.403~0.481. The highest metal content in PcS1. And the bigger particle diameter, the lower the valuable metals exist. The recovery rate of the valuable metals increases in smaller particle diameter with same leaching conditions. For further work, it could improve to recovery of the valuable metals effectively by means of individual treatment, multistage leaching and different leaching solvents.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.8
• /
• pp.76-85
• /
• 2003

In this paper, a technical method for removing the solder from PCBs has been proposed to simplify the pulverizing process and to get higher quality of materials for recycling of the electronic parts in the Printed Circuit Boards (PCBs). There are several techniques to remove the solder from PCB, such as physical and chemical method, vibration, suction and blowing and so on. Among them, the suction technique turned out the best method by investigation. In the suction method, there are three variables for removing the solder. They are a temperature of the thermal wire, a velocity of moving PCB and a gap between PCB and thermal wire. To find the optimal variables for the system, an experiment has been conducted by a trial and error method. The optimal variables were found $220^{\circ}C$ of temperature, 11.58mm/s of velocity, 10mm of gap (A gap between suction hole and bottom of PCBs is 5mm). The result of the experiment shows that 50% of the solder were removed.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.1
• /
• pp.35-42
• /
• 2003

Differential signaling has become a popular choice for high-speed interconnection schemes on Printed Circuit Boards (PCBs), offering superior immunity to external noise. However, conventional differential transmission lines on PCBs have problems, such as crosstalk and radiated emission. To overcome these, we propose a Twisted Differential Line (TDL) structure on a multi-layer PCB. Its improved immunity to crosstalk noise and the reduced radiated emission has been successfully demonstrated by measurement. The proposed structure is proven to transmit 3 Gbps digital signals with a clear eye-pattern. Furthermore, it is subject to much less crosstalk noise and achieves a 13 dB suppression of radiated emission. Index Terms - Twisted Differential Line, Differential Signaling, Crosstalk, Radiated Emission, Transmission Line, Twisted Pair

• IE interfaces
• /
• v.13 no.2
• /
• pp.195-203
• /
• 2000

This paper considers the problem of sequencing printed circuit boards(PCBs) on an automatic surface mount device(SMD) placement machine in order to minimize total setup time. Since the total set of component feeders needed by all boards cannot be loaded simultaneously on the magazine, the setup must be made between two successive boards in the sequence. It is assumed that the setup time depends on the number of component feeders to be replaced in the magazine. An important characteristic is that each feeder occupies a different number of slots in the magazine. This problem is equivalent to travelling salesman problem(TSP) except that the distances between two cities, that is, the setup times between two boards, are not known in advance. So, TSP-based heuristics with new distance functions are presented and their performances are compared through various test problems. Computational results indicate that our heuristics outperform existing methods.

• Resources Recycling
• /
• v.11 no.2
• /
• pp.28-35
• /
• 2002

A study on the grinding characteristics of metal components in printed circuit boards (PCBs) scrap by a swing-hammer typeimpact mill was conducted. The PCBs scrap crushed to sizes less than 3 mm were pulverized to liberate metal components by the impact mill. The effect of rotation speed of hammer on the grinding characteristics was investigated. The particle size distribution and degree of liberation of metals such as copper and solder were measured. The effect of rotation speed and particle size on the shape sorting of metal Particles from milled PCBs was investigated using an inclined vibrating Plate. At the hammer speed of 61.3 m/s about 80% of the copper particles became larger than 297 $\mu$m while 90% of solder particles was smaller than 297 $\mu$m. In the shape sorting method, the recovery location becomes shorter as the rotation speed of hammer increases. The recovery location for particles larger than 297$\mu$m was shorter than for particles sized between 149$\mu$m and 297$\mu$m. As the recovery location becomes shorter, KI value increases towards unity while $\phi_{c}$ value decreases towards unity indicating the more roundness of metal particles.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.11a
• /
• pp.87-88
• /
• 2007

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.2
• /
• pp.1-8
• /
• 2016

Generally, electrical circuits are fabricated as Printed Circuit Boards (PCBs) and mounted on the casing of the product. Additionally, this requires many other parts and some labor for assembly. Recently, molding technology has increasingly been applied to embed simple circuits in plastic casing. The technology is called a Molded Interconnected Device (MID). By using this technology, PCB fabrication can be replaced by molding, and much of the corresponding assembly process for PCBs can be eliminated if the circuit is simple enough for molding. Furthermore, as the improvement of conductive materials and printing technologies of simple electric circuits can be printed directly on the casing part, this also reduces the complexity of the product design and production cost. Therefore, this paper introduces a new MID fabrication process using direct 3D printing technology. Additionally, it is applied to an automotive part of a cruise control switch. The methodology and design are shown.

• Resources Recycling
• /
• v.24 no.1
• /
• pp.66-72
• /
• 2015

Various waste PCBs arose during disassembly of LCD TVs and monitors in which they originally functioned for transmission of imaging signal, power supply, and imaging control. In those functional PCBs, gold and copper are contained at far more acceptable level, exceeding mining grade ores. Those valuable metals and their contents widely vary with functionality and end use of PCBs. Therefore, compositional analysis of individual waste PCBs from disassembled LCD TVs and monitors were performed in the present study to classify them into three categories: high gold yield and low gold yield PCBs and those without gold contents. Besides, additional chemical analysis was made to reveal gold and copper contents in the waste PCBs arising from actual disassembly/separation of end-of-life LCD TVs and monitors.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.321-325
• /
• 2007

Recently, demands on thin multi-layer printed circuit boards(PCB) have been rapidly increased with broad spread of personal portable digital appliances such as multi-media. In case of mobile phone, however, the fact that PCBs have low flexural strength might cause defects. The purpose of this study is to improve the flexural strength by substituting the well-known GFRP(glass fiber reinforced plastic) for CFRP(carbon fiber reinforced plastic). Firstly, finite element simulation was carried out using ABAQUS to find out a unique CFRP layer that has a role to sustain the applied forces mainly in PCB. Secondly, three point bending tests were conducted with the newly designed CFRP PCB model to verify the improvement of the flexural strength. Consequently, it is shown that PCB layered with the CFRP on both outer sides of the board can be used to improve the flexural strength effectively.