• Journal of Welding and Joining
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• v.2 no.2
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• pp.29-37
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• 1984

발전설비를 비롯한 산업설비, 각종 압력용기 및 철구조물 제작시 발생하는 여러가지의 용접불량 중에서 슬래그 혼입이 차지하는 비율이 전체 불량의 절반 이상을 차지하고 있다. 특히 여타의 용접법에 비해 SMAW에 의한 슬래그 혼입의 발생이 가장 많으므로 이에 대한 결함 발생의 경향을 조사하고 그 방지대책을 설정하기 위하여 이번 실험을 실시하게 되었다. 수동 용접봉의 피복제 중 가스 발생 원인은 아아크 분위기를 생성하고 기타 부분은 슬래그가 되어 용융금속을 둘러싸서 이것을 보호하면서 용융지로 이행한다. 슬래그는 용융지 내에서 비이드 표면으로 부상하면서 탈산반응이나 불순물을 제거하는 정련작용을 한다. 또한 적당한 합금 원소의 보충, 용융금속의 유동성 증가 등에 의하여 양호한 용착금속의 생성을 돕는다. 한편, 슬래그는 고온금속을 덮어 이것을 보호함과 동시에 급냉을 완화하는 작용을 한다. 그러나 이러한 슬래그가 응고하는 용착금속 사이에 혼입된다면 용착금속의 기계적 성질을 저하시키는 중요한 요인이 된다. 슬래그 혼입에 대하여 간단하고 일반적인 방지대책은 많이 언급되어 있으나 슬래그 혼입의 방지대책에 대해 깊이 있는 연구가 거의 없다. 이번 실험에서는 광범위한 요인의 선제, 싯수의 제안으로 인하여 새로운 슬래그 혼입 기구의 설정이나 특정한 요인의 영향에 대한 정확한 한계치의 설정보다는 각 요인에 대한 정성적인 영향을 분석하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.284-284
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• 2015

반도체 Ball Grid Array(BGA)에 사용되던 종래의 Solder Ball은 Sn96.3 Ag3.0 Cu0.7의 용융솔더를 이용하여 제작하고 있다. 이는 SMT Reflow공정에서 BGA Ball의 퍼짐현상으로 인해 원래의 Ball Height에 영향을 미쳐 접합불량의 원인이 되고 있다. 이러한 문제를 해결하기 위해 Copper Core Ball위에 SnAgCu 삼원합금도금공정을 이용해 문제점을 해결하고자 했으며, 본 실험을 통해 구현한 CCSB를 이용해 SMT Reflow를 진행한 결과 종래의 BGA Ball보다 우수한 효과를 확인할 수 있었다.

• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.31-36
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• 2004

Electrofusion(EF) joints have been widely used as they are easy to fuse and suitable for high-quality joints for polyethylene(PE) pipes. This paper studies the cause of defects and classifies 5 types of defects. The defect detection technique for electrofusion joints of polyethylene piping is utilized by the ultrasonic phased array technique to obtain ultrasonic images of electrofusion joints. Test sample joints have been designed and fabricated using artificial defects which were made using paper. Finally, we studied the condition of electrofusion in the field and analyzed the main causes of defects. And we classified the defect types as local lack of fusion, sand inclusion, voids or air inclusion, short stab, excess penetration or excess bead.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.10-16
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• 2011

A cabinet is an outer frame of a TV, which is usually made of poly-carbonate. Cabinets are apt to be deformed because of applied heat during injection molding process and UV joining process. Severely deformed cabinets cause a falling-off in quality of the final product. Therefore cabinets should be inspected and only the good ones should be delivered to the following process. We implemented an experimental system for shape recognition of a cabinet and proposed several indices to characterize the shape of a cabinet. We also proposed algorithms to eliminate the possible bias present in measured data and to check the goodness of a cabinet. Experimental results show the feasibility of the propose algorithms.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.40-47
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• 2016

Instead of metal connector generally used on the structural glued laminated timber rahmen joints, the GFRP reinforced laminated plates combining veneer and GFRP (Glass Fiber Reinforced Plastic) and bonded type GFRP rod were used as the connectors. As a result of moment resistance performance evaluation on the joint part applied with these connectors, the yield moment of specimen using the GFRP reinforced laminated plates and GFRP rod pin was measured 4 % lower in comparison to the specimen (Type-1) using the metal connectors, but the initial rotational stiffness was measured 29% higher. Also, the yield moment and rotational stiffness of the specimen using the GFRP-reinforced laminated plates and wood (Eucalyptus marginata) pin showed were measured 11% and 56% higher in comparison to the Type-1 specimen, showing the best performance. It was also confirmed through the failure shape and perfect elasto-plasticity analysis that it showed ductility behavior, not brittle fracture, from the shear resisting force by the pin and the bonding strength increased and the unification of member was carried out. On the other hand, in case of the specimen bonded with GFRP rod, it was impossible to measure the bonding performance or it was measured very low due to poor bonding.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.33-38
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• 2007

We studied a bonding at low temperature using polymer bump and Non-Conductive Adhesive (NCA), and studied the reliability of the polymer bump/Al pad joints. The polymer bumps were formed on oxidized Si substrates by photolithography process, and the thin film metals were formed on the polymer bumps using DC magnetron sputtering. The substrate used was AL metallized glass. The polymer bump and Al metallized glass substrates were joined together at $80^{\circ}C$ under various pressure. Two NCAs were applied during joining. Thermal cycling test ($0^{\circ}C-55^{\circ}C$, cycle/30 min) was carried out up to 2000 cycles to evaluate the reliability of the joints. The bondability was evaluated by measuring the contact resistance of the joints through the four point probe method, and the joints were observed by Scanning Electron Microscope (SEM). The contact resistance of the joints was $70-90m{\Omega}$ before the reliability test. The joints of the polymer bump/Al pad were damaged by NCA filler particles under pressure above 200 MPa. After reliability test, some joints were electrically failed since thinner metal layers deposited at the edge of bumps were disconnected.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.85-90
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• 2011

With regard to reliability of solder joint, the significant failures include open defects that occurs from alignment problem, Head in Pillow by PCB's warpage, the crack of solder by CTE mismatch, and the crack of IMC layer by mechanical impact. Especially as PCB down-sizing and surface finish is under progress, brittle failure of IMC layer between solder bump and PCB pad becomes a big issue. Therefore, it requires enhancing the level of difficulty in the existing assessment method and improving the measurement through the study on the mechanism of IMC formation, growth and brittle failure. Under this circumstance, this study is intended to suggest the direction of research for improving the reliability on the crack such as improvement of IMC brittle fracture.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.306-316
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• 2016

In this paper, an NMOS-diode eFuse OTP (One-Time Programmable) memory cell is proposed using a parasitic junction diode formed between a PW (P-Well), a body of an isolated NMOS (N-channel MOSFET) transistor with the small channel width, and an n+ diffusion, a source node, in a DNW (Deep N-Well) instead of an NMOS transistor with the big channel width as a program select device. Blowing of the proposed cell is done through the parasitic junction formed in the NMOS transistor in the program mode. Sensing failures of '0' data are removed because of removed contact voltage drop of a diode since a NMOS transistor is used instead of the junction diode in the read mode. In addition, a problem of being blown for a non-blown eFuse from a read current through the corresponding eFuse OTP cell is solved by limiting the read current to less than $100{\mu}A$ since a voltage is transferred to BL by using an NMOS transistor with the small channel width in the read mode.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1702-1703
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• 2011

MEMS 소자의 Wafer level Package 관련하여 Deep cavity를 가진 Cap Wafer와 Polymer bonding 중 cavity 단차로 인한 Polymer Patterning 및 접합 불량의 어려움을 극복할 수 있는 새로운 공정 flow를 제안하였다. Cavity를 형성할 때 사용하는 Si deep etching Mask인 기존의 Photoresist를 접합용 감광성 Polymer로 대체하고, cavity 형성 후, 별도의 추가 공정 없이 이 Polymer를 이용해 Wafer bonding을 진행하였다. 이를 통해 cavity 단차에 따른 문제를 해결함과 동시에 공정이 단순하고 제작 비용이 저렴하며, 신뢰성 있는 Wafer level Package를 구현하였다.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.115-115
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• 2009

아연코팅강판의 레이저 용접시 발생하는 용접결함은 이미 널리 알려진 이슈이다. 그러나 대부분의 연구가 박판을 중심으로 이루어지고 있어서, 후판을 중심으로 한 조선산업에서의 아연코팅 강판의 연구는 매우 미진한 실정이다. 이중 후판 아연코팅강판의 결함검출연구는 그 연구가 거의 전무한 실정으로, 본 연구에서는 후판 아연코팅강판의 레이저 겹치기용접시의 결함검출을 중심으로 실험을 실시하였다. 실험은 Fig. 1에서와 같이 광신호와 음향신호의 RMS를 통하여 raw signal에서 잘 나타나지 않았던 신호의 패턴을 확인함으로써 실제 신호와 비드와를 대응을 가능하게 하였다. 또한 결함 발생시의 RMS값을 건전한 상태와 비교분석하여 실제 결함검출의 가능성도 확인할 수 있었다.