• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.120-125
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• 2008

A flip-chip bonding system using DPSS(Diode Pumped Solid State) Nd:YAG laser(wavelength : 1064nm) which shows a good quality in fine pitch bonding is developed. This laser bonder can transfer beam energy to the solder directly and melt it without any physical contact by scanning a bare chip. By using a laser source to heat up the solder balls directly, it can reduce heat loss and any defects such as bridge with adjacent solder, overheating problems, and chip breakage. Comparing to conventional flip-chip bonders, the bonding time can be shortened drastically. This laser precision micro bonder can be applied to flip-chip bonding with many advantage in comparison with conventional ones.

• Ceramist
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• v.9 no.6
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• pp.30-36
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• 2006

Joining ceramics to metals has a variety of applications both in the structural and the electronics fields. One of the great benefits of the adoption of joining into the structural applications is to provide reliability to the ceramic components by backing up with metal components. In joining ceramics and metals, two key factors, i.e., establishing chemical bonding at interfaces and dissipation of thermal stress across interfaces, should be paid for attention. Many joining methods have been already established such as adhesive and mechanical joining, brazing and soldering, and solid state bonding. Each has its own benefits with some drawbacks. One can select a suitable process and materials following the requirements of the application. This report focuses on the current status of joining technology for ceramics/metal system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.92-99
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• 2021

The ever-growing demand for enhanced competitiveness of engineered systems require designing in quality strategies that can efficiently incorporate multiple design attributes into a system. In a robust design, there must be consideration for any uncontrollable factors that should not be disregarded in the design process. Studies on multi-attribute design challenges usually assume mutual utility independence amongst the design attributes. However, mutual utility independence does not exist in every design situation. In this study, a new robust design methodology that has two utility-dependent attributes are presented. The proposed method was then compared with a traditional robust design that utilizes a wave soldering process design. The results of this case study indicate that the proposed method yields a better solution than the traditional method.

• The Journal of the Convergence on Culture Technology
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• v.4 no.3
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• pp.209-212
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• 2018

Anisotropic conductive film(ACF) bonding is widely used for making fine interconnections between two different materials where soldering is not easily applicable. There are three constraints for the successful implementation of ACF bonding. A bonding contact should be pressed by a hot head with the right pressure and temperature for a pre-defined curing time. In this paper, a method for ACF bonding based on machine vision system is proposed and verified through some experiments. The system calculates the position and orientation of printed circuit boards(PCBs) on a bonding table and estimates the optimal hitting point where the hot head should be applied. Experimental results show that the proposed system achieves better adhesive strength by providing head flatness over contact surfaces.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.65-68
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• 1999

In this study, an off-line automatic teaching method using vision information for robotic assembly task is proposed. Many of industrial robots are still taught and programmed by a teaching pendant. The robot is guided by a human operator to the desired application locations. These motions are recorded and are later edited, within the robotic language using in the robot controller, and played back repetitively to perform the robot task. This conventional teaching method is time-consuming and somewhat dangerous. In the proposed method, the operator teaches the desired locations on the image acquired through CCD camera mounted on the robot hand. The robotic language program is automatically generated and transferred to the robot controller. This teaching process is implemented through an off-line programming(OLP) software. The OLP is developed for the robotic assembly system used in this study. In order to transform the location on image coordinates into robot coordinates, a calibration process is established. The proposed teaching method is implemented and evaluated on the assembly system for soldering electronic parts on a circuit board. A six-axis articulated robot executes assembly task according to the off-line automatic teaching.

• The Journal of Advanced Prosthodontics
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• v.4 no.4
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• pp.254-258
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• 2012

Implant-supported overdenture is a reliable treatment option for the patients with edentulous mandible when they have difficulty in using complete dentures. Several options have been used for implant-supported overdenture attachments. Among these, bar attachment system has greater retention and better maintainability than others. SFI-Bar$^{(R)}$ is prefabricated and can be adjustable at chairside. Therefore, laboratory procedures such as soldering and welding are unnecessary, which leads to fewer errors and lower costs. A 67-year-old female patient presented, complaining of mobility of lower anterior teeth with old denture. She had been wearing complete denture in the maxilla and removable partial denture in the mandible with severe bone loss. After extracting the teeth, two implants were placed in front of mental foramen, and SFI-Bar$^{(R)}$ was connected. A tube bar was seated to two adapters through large ball joints and fixation screws, connecting each implant. The length of the tube bar was adjusted according to inter-implant distance. Then, a female part was attached to the bar beneath the new denture. This clinical report describes two-implant-supported overdenture using the SFI-Bar$^{(R)}$ system in a mandibular edentulous patient.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.102-106
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• 2012

The purpose of this paper is to study the failure cases in relation to system of Air Bag in vehicle happened in the field. In the first example, it was separated the soldering parts connected the wire pin between air bag module and clock spring of air bag. Whenever the pin shake by the car's vibration, the driver verified the malfunction phenomenon appeared air bag warning lamp on instrument panel in front of driver's seat. in car inside room. The second example, it verified the warning lamp lighting phenomenon of air bag by produced the circuit plate non-contacting of single an element in air bag electronic control unit. The third example, it verified the light of air bag warning indicator lamp by separated with soldering parts connecting inner pin and resistance terminal of seat belt pretensioner using passenger seat. The fourth example, when the passenger car crash a back of truck, the former bumper get jammed under the latter as the roof height of car low less than that. Therefore, the impact of Car's collision verified that don't transfer with body frame of vehicle because of no attachment impact sensor in it.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.11
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• pp.1089-1095
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• 2010

We propose an image segmentation method for auto-teaching system of PCB (Printed Circuit Board) assembly inspection machines. The inspection machine acquires images of all components in PCB, and then compares each image with its standard image to find the assembly errors such as misalignment, inverse polarity, and tombstone. The component window that is the area of component to be acquired by camera, is one of the teaching data for operating the inspection machines. To reduce the teaching time of the machine, we newly develop the image processing method to extract the component window automatically from the image of PCB. The proposed method segments the component window by excluding the soldering parts as well as board background. We binarize the input image by use of HSI color model because it is difficult to discriminate the RGB colors between components and backgrounds. The linear combination of the binarized images then enhances the component window from the background. By use of the horizontal and vertical projection of histogram, we finally obtain the component widow. The experimental results are presented to verify the usefulness of the proposed method.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.450-455
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• 2002

Cu-cored Sn-Ag solder balls were fabricated by coating pure Sn and Ag on Cu balls. The melting behavior and the solderability of the BGA joint with the Ni/Au coated Cu pad were investigated and were compared with those of the commercial Sn-Ag and Sn-Ag-Cu balls. DSC analyses clarified the melting of Cu-cored solders to start at a rather low temperature, the eutectic temperature of Sn-Ag-Cu. It was ascribed to the diffusion of Cu and Ag into Sn plating during the heating process. After reflow soldering the microstructures of the solder and of the interfacial layer between the solder and the Cu pad were analyzed with SEM and EPMA. By EDX analysis, formation of a eutectic microstructure composing of $\beta$-Sn, Ag$_3$Sn, ad Cu$_{6}$Sn$_{5}$ phases was confirmed in the solder, and the η'-(Au, Co, Cu, Ni)$_{6}$Sn$_{5}$ reaction layer was found to form at the interface between the solder and the Cu pad. By conducting shear tests, it was found that the BGA joint using Cu-cored solder ball could prevent the degradation of joint strength during aging at 423K because of the slower growth me of η'-(Au, Co, Cu, Ni)$_{6}$Sn$_{5}$ reaction layer formed at the solder, pad interface. Furthermore, Cu-cored multi-component Sn-Ag-Bi balls were fabricated by sequentially coating the binary Sn-Ag and Sn-Bi solders on Cu balls. The reflow property of these solder balls was investigated. Melting of these solder balls was clarified to start at the almost same temperature as that of Sn-2Ag-0.75Cu-3Bi solder. A microstructure composing of (Sn), Ag$_3$Sn, Bi and Cu$_{6}$Sn$_{5}$ phases was found to form in the solder ball, and a reaction layer containing primarily η'-(Au, Co, Cu, Ni)$_{6}$Sn$_{5}$ was found at the interface with Ni/Au coated Cu pad after reflow soldering. By conducting shear test, it was found that the BGA joints using this Cu-core solder balls hardly degraded their joint shear strength during aging at 423K due to the slower growth rate of the η'-(Au, Cu, Ni)$_{6}$Sn$_{5}$ reaction layer at the solder/pad interface.he solder/pad interface.

• Tribology and Lubricants
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• v.30 no.3
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• pp.183-188
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• 2014

In this paper, we present our analysis of tribological failure examples for an anti-lock brake system(ABS) in a car. The study range of this paper is to improve the quality of ABS system by analyzing with sensor, computer, actuator and oil lines. In the first example, the brake leak from hydraulic supply line in a caliper on the rear left side of the ABS hydraulic modulator. This produces the sponge phenomenon, where the car does not brake even when the driver operates the brake pedal. The hydraulic unit operating ABS is actuator that play role regulating drive condition according with the oil pressure supplied with wheel of a car. In the second example, the service man does not completely tighten the fixed bolt after repairing the car. This causes the ABS warning lamp to light up as the ABS wheel speed sensor cannot detect whether the ABS has been activated. In the third example, the ABS electronic control unit is separated from the soldered part of the inner circuit board. Consequently, the ABS fails in control because the ABS motor pump receives no-signal for the hydraulic unit. The wheel speed sensor has to large durability because of giving signal of acting condition to computer by detected the acceleration and deceleration of wheel of a car. In the fourth example, the ABS warning lamp lights up of when cracks propagate in the circuit board soldering part. The circuit of this computer is very important part for input and output the operating signal of system. Such failures can aggravate the durability of the ABS. Thus, the ABS needs to be optimized to eliminate malfunction phenomenon.