• Carbon letters
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• v.21
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• pp.68-73
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• 2017

We have demonstrated the production of thin films containing multilayer graphene-coated copper nanoparticles (MGCNs) by a commercial electrodeposition method. The MGCNs were produced by electrical wire explosion, an easily applied technique for creating hybrid metal nanoparticles. The nanoparticles had average diameters of 10-120 nm and quasi-spherical morphologies. We made a complex-electrodeposited copper thin film (CETF) with a thickness of $4.8{\mu}m$ by adding 300 ppm MGCNs to the electrolyte solution and performing electrodeposition. We measured the electric properties and performed corrosion testing of the CETF. Raman spectroscopy was used to measure the bonding characteristics and estimate the number of layers in the graphene films. The resistivity of the bare-electrodeposited copper thin film (BETF) was $2.092{\times}10^{-6}{\Omega}{\cdot}cm$, and the resistivity of the CETF after the addition of 300 ppm MGCNs was decreased by 2% to ${\sim}2.049{\times}10^{-6}{\Omega}{\cdot}cm$. The corrosion resistance of the BETF was $9.306{\Omega}$, while that of the CETF was increased to 20.04 Ω. Therefore, the CETF with MGCNs can be used in interconnection circuits for printed circuit boards or semiconductor devices on the basis of its low resistivity and high corrosion resistance.

• Progress in Medical Physics
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• v.26 no.2
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• pp.99-105
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• 2015

The monitor chamber is a real time dosimetry device for the measurement and the control of radiation beam intensity of the linac system. The monitor chamber prototype was developed for monitoring and controlling radiation beam from the linac based radiation generator. The thin flexible printed circuit boards were used for electrodes of the two independent plane-parallel ionization chambers to minimize the attenuation of radiation beam. The dosimetric characteristics, saturation and linearity of the measured charge, were experimentally evaluated with the Co-60 gamma rays. The performance of the developed monitor chamber prototype was in an acceptable range and this study shows the possibility of the further development of the chamber with additional functions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6289-6295
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• 2014

Rework systems are the equipment used to install or remove semiconductor chips with BGA or SMD forms in printed circuit boards. The rework systems have hot air outlets. At the outlets, precise temperature control is needed to avoid heat shock. The aim of this paper was to suggest a new controller for temperature control at the hot air outlets. The suggested controller was a fuzzy PID controller. The fuzzy PID controllers were composed of TSK fuzzy rules and had outstanding ability for nonlinear systems control. This paper reports the design algorithm of fuzzy PID controllers, and the design process of the fuzzy PID controller for the temperature control of the outlets. Temperature control experiments were performed to verify the ability of the suggested controller. As a result, the RMS of the proposed method is 9.44 and the general method is 15.88. The experiments showed that the temperatures at the outlet using the suggested fuzzy PID controller followed the desired ones better than the commonly used PID controller.

• Polymer(Korea)
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• v.24 no.3
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• pp.350-357
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• 2000

Curing behaviors of glass/epoxy prepreg for printed circuit boards (PCB) were studied by using dielectrometer and differential scanning calorimeter. This prepreg was showed the lowest ionic viscosity at about 115$^{\circ}C$, and then the ionic viscosity was gradully increased up to 15$0^{\circ}C$. This indicated that the curing reaction of this prepreg started at 115$^{\circ}C$ and the molecular weight was increased by the accelerated thermal cross-linking reaction. The loss factor and tan $\delta$ values were also measured and discussed. The dielectric behaviors of this prepreg system were also measured according to the cure cycle for PCB. This material was found to be thermally stable up to about 30$0^{\circ}C$ and then was showed an abrupt decomposition beyond this temperature.

• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.342-348
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• 2021

For the characterization or failure analysis of electronic devices such as PCB (printed circuit boards), the most common method is the measurement of voltage waveforms with an oscilloscope. However, because there are many types of problems that cannot be detected by voltage waveform analysis, several other methods such as X-ray transmission, infrared imaging, or eddy current measurement have been applied for these analyses. However, these methods have also been limited to general analyses because they are partially useful in detecting physical defects, such as disconnections or short circuits. Fundamentally current waveform measurements during the operation of electronic devices need to be performed, however, commercially available current sensors have not yet been developed, particularly for applications in highly integrated PCB products with sub-millimeter fine pitch. In this study, we developed a highly sensitive PHR (planar hall resistance) magnetic sensor for application in highly integrated PCBs. The developed magnetic sensor exhibited sufficient features of an ultra-small size of less than 340 ㎛, magnetic field resolution of 10 nT, and current resolution of 1 mA, which can be applicable for PCB analyses. In this work, we introduce the development process of the magnetic sensing probe and its characteristic results in detail, and aim to extend this pin-type current probe to applications such as current distribution imaging of PCBs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.1-6
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• 2018

This study examined the quality improvement of printed circuit boards (PCBs) in relation to the power consumption for radar. The radar examined is currently in production and being used by the military. The PCB converts 28 V DC to 5 V DC but frequently malfunctions. Therefore, cause analysis was carried out. As a result, the power consumed by a certain communication IC was very high, and the heat generated by the high power consumption caused damage to the surrounding parts. Accordingly, it was changed to an improved communication IC that meets all the radar system specifications. System tests were carried out for the changed communication IC to check the impact on the system, and environmental tests were performed, which proved that the performance required by the radar system is satisfactory. As a result of this improvement, there has been no history of failure in this PCB so far. Therefore, the quality of this PCB has been improved.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.460-468
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• 2022

Due to its high electrical conductivity, low contact resistance, good weldability and high corrosion resi-stance, gold is widely used in electronic components such as connectors and printed circuit boards (PCB). Gold ion salts currently used in gold plating are largely cyan-based salts and non-cyanic salts. The cya-nide bath can be used for both high and low hardness, but the non-cyanide bath can be used for low hardness plating. Potassium gold cyanide (KAu(CN)₂) as a cyanide type and sodium gold sulfite (Na₃[Au(SO)₃]₂) salt as a non-cyanide type are most widely used. Although the cyan bath has excellent performance in plating, potassium gold cyanide (KAu(CN)₂) used in the cyan bath is classified as a poison and a toxic substance and has strong toxicity, which tends to damage the positive photoresist film and make it difficult to form a straight side-wall. There is a need to supplement this. Therefore, it is intended to supplement this with an eco-friendly process using sodium sulfite sodium salt that does not contain cyan. Therefore, the main goal is to form a gold plating layer with a controllable hardness using a non-cyanide gold plating solution. In this study, the composition of a non-cyanide gold plating solution that maintains hardness even after annealing is generated through gold-palladium alloying by adding thallium, a crystal regulator among electrolysis factors affecting the structure and hardness, and changes in plating layer structure and crystallinity before and after annealing the correlation with the hardness.

• Resources Recycling
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• v.30 no.4
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• pp.3-10
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• 2021

The field of recycling for waste electronic components, which is the typical example of an urban mine, requires the development of useful sorting techniques. In this study, a sorter based on image identification by deep learning was developed to select electronic components into four groups. They were recovered from waste printed circuit boards and should be separated to depend on the difference after treatment. The sorter consists of a workstation with GPU, camera, belt conveyor, air compressor. A small piece (less than 3.5 cm) of electronic components on the belt conveyor (belt speed: 6 cm/s) was taken and learned as teaching data. The accuracy of the image identification was 96% as kinds and 99% as groups. The optimum condition of sorting was determined by evaluating accuracies of image identification and recovery rates by blowdown when changing the operating condition such as belt speed and blowdown time of compressed air. Under the optimum condition, the accuracy of image classification in groups was 98.7%. The sorting rate was more than 70%.

• Journal of Powder Materials
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• v.30 no.4
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• pp.356-362
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• 2023

Inorganic-organic composites find extensive application in various fields, including electronic devices and light-emitting diodes. Notably, encapsulation technologies are employed to shield electronic devices (such as printed circuit boards and batteries) from stress and moisture exposure while maintaining electrical insulation. Polymer composites can be used as encapsulation materials because of their controllable mechanical and electrical properties. In this study, we propose a polymer composite that provides good electrical insulation and enhanced mechanical properties. This is achieved by using aluminum borate nanowhiskers (ABOw), which are fabricated using a facile synthesis method. The ABOw fillers are created via a hydrothermal method using aluminum chloride and boric acid. We confirm that the synthesis occurs in various morphologies based on the molar ratio. Specifically, nanowhiskers are synthesized at a molar ratio of 1:3 and used as fillers in the composite. The fabricated ABOw/epoxy composites exhibit a 48.5% enhancement in mechanical properties, similar to those of pure epoxy, while maintaining good electrical insulation.

• Journal of Practical Engineering Education
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• v.16 no.2
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• pp.179-184
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• 2024

Printed circuit boards (PCBs) are a key component widely used in the production of electronic products, and not only quantitative growth but also qualitative developments such as integration cannot be ignored. Wave soldering equipment is commonly used equipment at manufacturing sites, but it is impossible to configure a dedicated equipment environment suitable for each PCB specification during the preliminary research and prototype development stage. It is neither suitable for development within limited time line nor manufacturing various product groups because only equipment setting conditions can be changed within a given time. In this study, we introduce a case of introducing a PCB pallet to enable selection of optimal process conditions within the limited environment described above. In addition, by presenting a discriminant that can determine in advance whether production is possible with current general-purpose equipment, it is expected that problems that may arise due to limitations in the general-purpose wave soldering equipment environment can be identified and resolved in advance. Ultimately, this palette makes it possible to shorten the development period and improve productivity.