• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1365-1367
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• 2003

In this paper, element technologies such as soldering. arrangement and lamination processes for photovoltaic module manufacture were examined and described as main processes. Especially solder paste and temperature condition in soldering process, loss factor in arrangement process and process conditions in lamination process are investigated to minimize the electrical loss. As a results, temperature condition in soldering process was found to be critical to contact resistance of electrode and life-time. Productivity of the process decreases dramatically by physical damage during arrangement process. Pressure level and press condition of upper chamber in lamination process were important parameters for the reliability. According to the test result of photovoltaic module, electrical properties dropped about $5{\sim}25%$ after 5 years.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.1-8
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• 2020

In this paper, the principles, characteristics and recent studies of the laser micro soldering are reviewed. The factors which influence laser micro welding and soldering are also included. Laser soldering is a non-contact process that transfers energy to solder joint by a precisely controlled laser beam. In recent electronics industry, the demands for laser soldering are increasing due to bonding for complex circuits and local heating in micro-joint. In laser soldering, there are several important factors like laser absorption, laser power, laser scanning speed, and etc, which affect laser solderability. The laser absorption ratio depends on materials, and each material has different absorption or reflectivity for the laser beam, which requires fine adjustment of the laser beam. Laser types and operating conditions are also important factors for laser soldering performance, and these are also reviewed.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.7-13
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• 2019

In this paper, the principles, types and characteristics of the laser and laser soldering are introduced. Laser soldering methods for electronics, metals, semiconductors are also presented. Laser soldering is a non-contact process that transfers energy to solder joint by a precisely controlled beam. Demands for laser soldering are increasing due to bonding for complex circuits and local heating in micro joint. Laser absorption ratio depends on materials, and each material has different absorption or reflectivity of the laser beam, which requires fine adjustment of the laser beam. Laser types and operating conditions are also important factors for laser soldering performance. In this paper, the performance of Nd:YAG laser soldering is compared to the hot blast reflow. Meanwhile, a diode laser gives different wavelength and smaller parts with high performance, but it has various reliability issues such as heat loss, high power, and cooling technology. These issues need to be improved in the future, and further studies for laser micro-joining and soldering are required.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.402-407
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• 2002

Laminate tooling process is a fast and simple method to make metal tools directly for various molding processes such as injection molding in rapid prototyping field. Metal sheets are usually cut, stacked, aligned and joined with brazing or soldering. Through the joining process, all of the metal sheet layers should be rigidly joined. When joining process parameters are not appropriate, there would be defects in the layers. Among various types of defects, non-bonded gaps of the tool surface are of great importance, because they directly affect the surface quality and dimensional accuracy of the final products. If a laminate tool with defects has to be abandoned, it could lead to great loss of time and cost. Therefore a repair method for non-bonded gaps of the surface is essential and has important meaning for rapid prototyping. In this study, a rapid laminate tooling system composed of a CO2 laser, a furnace, and a milling machine was developed. Metal sheets were joined by furnace brazing, dip soldering and adhesive bonding. Joined laminate tools were machined by a high-speed milling machine to improve surface quality. Also, repair brazing and soldering methods of the laminates using the $CO_2$ laser system have been investigated. ill laser repair process, the beam duration, beam power and beam profile were of great importance, and their effects were simulated by [mite element methods. The simulation results were compared with the experimental ones, and optimal parameters for laser repair process were investigated.

• Journal of Welding and Joining
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• v.13 no.4
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• pp.14-23
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• 1995

Micro soldering 기술의 응용은 주로 전자제품에 이용되며, 특히 컴퓨터 정보 통신 기기의 집합.접속 기술의 중추적인 역할을 하고 있다. 아울러 이 분야는 일본, 미국이 선구적인 역할을 하고 있으며, 예를 들어 일본 전자산업의 1994년도 생산액이 앤 고의 열쇠에 불구하고 민생용.산업용 전자기기 및 전자 부품의 3부분에서 약 .yen.30조(250조원)에 달한 것으로 보면 그 규모 및 중요성을 알 수 있다. 이것은 기본 적으로 반도체의 집적도가 높아진것(LSI.rarw.VLSI.rarw.ULSI)과 아울러 소자를 접합 접속시키는 기술이 확보되었기 때문에 이루어진 결과라고 말할 수 있다. 따라서 본 기술 해설에서는 접합.접속 기술의 하나인 Micro soldering의 각종 프로세스 중에서 도 특히 기본이 되는 리플로우 프로세스(reflow process)를 중심으로 기술하였으며 아울러 신뢰성의 제반사항에 관하여 간략하게 기술하였다.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.231-233
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• 2005

Laser have been utilized as a heat source for the soldering of electronic components for the their capability of localized heating and faster heating rate. Laser soldering process, especially the diode laser soldering of BGA solderball was investigated. In this study, an attempt was made to investigate the possibility of laser soldering using Sn-37Pb and Sn-3Ag-0.5Cu solderball. The laser energy absorbed on the pad raised the temperature of the solderball forming a reflowed solder bump. The result were discussed based on the measurement of pull and shear strength of the bond.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.6
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• pp.574-581
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• 2020

This paper describes the stacking effect for Ceramic Column Grid Array(CCGA) packages used for satellites. Reflow Soldering Process suitable for CCGA package with back structure was set as the process development goal to meet European Cooperation for Space Standardization(ECSS) standard. After analyzing the stacking effect according to the type of CCGA, it is verified by applying it to the CCGA Reflow Soldering Process. In order to confirm the validity of the staking effect analyzed in terms of vibration and thermal characteristics, it is verified through actual specimen production. It analyzes the cause of crack occurrence in the CCGA package and estimates the crack generation point using previously acquired inspection data.

• Journal of Welding and Joining
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• v.16 no.5
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• pp.100-107
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• 1998

This paper describes fluxless soldering of reflow soldering process using solder foil instead of solder pastes. There is an increasing demand for the reliable solder connection in the recent high density microelectronic components technologies. And also, it is problem fracture of an Ozone layer due to freon as which is used to removal of remained flux on the substrate. This paper discussed joining phenomena, boudability and joining processes of microelectronics devices, such as between outer lead of VLSI package and copper pad on a substrate without flux. The shear strength of joints is 8 to 13 N using Sn/Pb (63/37 wt.%) solder foil with optimum joining conditions, meanwhile, in case of using Sn/In (52/48 wt.%) solder foil, it is possible to bond with low heating temperature of 550 K, and accomplish to high bonding strength of 25N in condition heating temperature of 650K. Finally, this paper experimentally shows fluxless soldering using solder foil, and accomplishes key technology of microsoldering processes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.661-662
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• 2006

This research is on a laser soldering using the micro solder-balls used in flip chip packaging process. A laser source used in laser soldering is Nd:YAG laser(250W and 60W). Solder-balls of 100, 300, $500{\mu}m$ size are used in experiments. The laser head to deliver a laser beam and the nozzle to transfer solder-balls are manufactured to bump solder-balls. After soldering solder-balls the shear test is carried out to determine the wetting at the interface between the surface and a solder-balls With the results of solder bumping tests a laminated molding is accomplished for manufacturing the three dimensional molding.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.63-69
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• 2012

As decreasing size of chips, the need of wafer level packaging is increased in semi-conductor and display industries. Temperature uniformity is a crucial factor in vacuum soldering process to guarantee quality of bonding between chips and wafer. In this paper, a stepwise iterative algorithm has been suggested to obtain output profile of each heat source. Since this algorithm is based on open-loop stepwise iterative experimental technique, it is easier to implement and cost effective than real time feedback controls. Along with some experiments, it was shown that the suggested algorithm can remarkably improve temperature uniformity of wafer during whole heating process compared with the ordinary manual trial-and error method.