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리플로우 시간에 따른 Sn-4Ag 솔더접합부 FEM 전단해석
유효선(Hyosun Yu),양성모(Sungmo Yang),손인덕(Indeok Son),최승준(Seungjun Choi) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
The evaluation on reliability of environment-friendly Pb-free solder and solder joints is very important. The correlation between interface reaction and mechanical properties of solder joints was confirmed in this study. And shear test are performed using SP(Share-Punch) tester. The shear strength tests on various reflow time are performed at 10,30,00 and 300sec. Tested specimens were examined in order to observe the failure mode on solder joints. The test result about solder joints of two different plate(Ni and Cu plate) are compared. Ni plate joints shown low IMC growth rate. The shear strength of Pb-free solder joints are higher than Sn-37 Pb solder joints, generally. In the case of Cu plate, shear strength of Sn-4Ag solder joints increased with reflow time. And solder joints with Cu contents are seems to similar in strength regardless of reflow time. on the other hand, in the case of Ni plate joints, shear strength of Sn-37Pb solder joints are similar to Sn-4Ag solder joints. Like Cu plate joints, solder joints with Cu contents are seems to similar in strength regardless of reflow time.
암석폐재의 고화체 합성기술의 개발과 파괴인성평가에 관한 연구
나의균,유효선,김진용,이종기,정세희,Na, Eui-Gyun,Yu, Hyosun,Kim, Jin-Yong,Lee, Jeong-Gee,Chung, Se-Hi 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.9
The hot press apparatus to obtain the solidified rocks with 60mm of diameter against rock waste was developed, and the optimum conditions for solidification were founded out, of which were 300.deg. C of temperature and 1hr of holding time. The solidified rocks reinforced with the fibers (carbon, steel) were made by means of a hydrothermal hot press method. Fracture toughness of those was obtained using the round compact tension(RCT) specimens. Load and displacement behaviours of the solidified rocks reinforced with the fibers were dependent upon the fiber volume fraction and kind of the fibers. Strength and fracture energy of the solidified rocks with steel were much larger than those of the solidified ones with carbon because of the Bridge's effect, multiple cracking and crack branching phenomena.
유길영(Kilyoung Yu),양성모(Sungmo Yang),유효선(Hyosun Yu) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Because of the Pb inherent toxicity, studies of Pb-free solder are increasing widely. Accordingly, the specimen in which it considers the intermetallic compound (IMC) in which it is generated a solder and copper plate in order to evaluate the shear property of the solder joints was predicted through the Shear-Punch test and FEM. By using the database according to this, the reliability evaluation technology of the solder joints tries to be formulated. In this paper, the solder used the Sn37Pb, Sn-4Ag and the Sn4ag0.5Cu. When solder melted in the copper interface, the solder joints according to reflow times (10sec, 30sec, 100sec, 300sec), each modeling required for the Shear-Punch was made in consideration of the IMC layer thickness. The shear properties the modeled specimen was predicted through FEM. It compared with the test value in which it obtains from Shear-Punch. Also, a method which can obtain shear properties of Pb-free solder joints easily and quickly using FEM was proposed.
유길영(Kilyoung Yu),양성모(Sungmo Yang),유효선(Hyosun Yu) 한국자동차공학회 2009 한국자동차공학회 지부 학술대회 논문집 Vol.2009 No.10
Every electronic equipment in vehicles, mobile phone or other machines is manufactured by soldering which is micro joining technology. Soldering is a method which connects two solids using molten solder and it is the most important technology in electronic assemblies of substrate, element, semi-conductor and joining part. Because of the Pb inherent toxicity, studies of Pb-free solder are increasing widely. Therefore it has to be the shear characteristic of a solder evaluated by a solder. By using the database according to this, the reliability evaluation technology of the solder joints tries to be formulated. In this paper, the solder used the Sn37Pb, Sn-4Ag and the Sn4ag0.5Cu. The shear properties the modeled specimen was predicted through FEM. It compared with the test value in which it obtains from Shear-Punch. Also, a method which can obtain shear properties of Pb-free solder joints easily and quickly using FEM was proposed.
이철민(Chulmin Lee),유효선(Hyosun Yu),강희용(Heeyong Kang),양성모(Sungmo Yang) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_3
The welding quality of spot weldment is very important because it dominates strength. stiffness. safety and etc of vehicles. Therefore. quality control and fatigue life evaluation of spot weldment are necessary process. This paper presented a method for determining the fatigue life of 3-lap spot weldment of galvanize steel and high strength steel sheet. To examine the validity of the proposed fatigue life equation and S-N curve, the fatigue life is estimated using the lethargy coefficient as the total defect estimation coefficient from the tensile-shear test. Then this result of calculation was compared to the result of fatigue test. This method can save the time and the cost in processing of predicting the life cycle of a structure.
환경친화적 Pb-free solder/Cu Pad 접합부의 크리프 특성
함영필(Youngpil Ham),유효선(Hyosun Yu),양성모(Sungmo Yang) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
In this research, the creep time to rupture of 2 solder joints according to the reflow times (10sec, 30sec, 100sec, 300sec) was compared against the Pb eutectic solder (Sn-37Pb) joint which performed the Shear Punch-Creep test of the Sn-4Ag/Cu Pad joints and by using the Sn-4Ag, that is the lead-free solder alloy, that is the environmentally friendly of the electronic component, in which presently the use is limited to the environment problem and the creep resistance of the Pb-free Sn-4Ag solder alloy was evaluated. When comparing the creep life about 3 reflow times, in case it reflowed about 2 solder joint departments with 100sec, the time to rupture which is the longest in 37h and Sn-37Pb in Sn-4Ag for 0.26h was displayed. In addition, when considering the time to rupture, the creep strength of the Sn-4Ag of the time to rupture of the Sn-4Ag solder joint is especially more excellent in the identical creep stress condition to the time to rupture of the Pb eutectic solder joint over the maximum hundredfold with each reflow time since exposed to is being long.
송준혁(Joonhyuk Song),유효선(Hyosun Yu),강희용(Heeyong Kang),양성모(Sungmo Yang) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Spot welding process is completed in very short time and there are many factors affecting on the generation of welding defects. There are difficult to control experimental factors. Even more this is hard to monitor of distribution stress in practical cases. The purpose of this study is to investigate the applicability of infrared thermagraphy for the evaluation of spot weldability in view of fatigue life. In this study, infrared stress analysis adopting an infrared thermography for nondestructive evaluation of spot weldability is investigated. Using temperature and IR stress distribution obtained by infrared camera from adiabatic heat expansion under a repeated load of sinusoidal waves, we estimated the fatigue quality index of spot welded specimens. And evaluated corrected S-N curve from original fatigue life curve of base metal.
SP시험을 이용한 Al6061-T6의 마찰교반용접부 파괴인성 평가
이용준(YongJun Lee),유효선(Hyosun Yu),양성모(Sungmo Yang),송준혁(Joonhyuk song),김경재(Kyungjae Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Recently, friction stir welding technology to the purpose for lightweight has been invested. For this reason, the various studies of friction stir welding using aluminum alloy have been needed. In this paper, Al6061-T6 alloy was welded to 3 conditions(rotation speed :1000rpm, feed rate:270, 300, 330mm/min). To evaluate fracture toughness values of welded joint, Small Punch test was used to with two cases of the load rate. The specimens which were classified by advancing side(AS), retreating side(RS) and center(C) were taken in the top of weldment. As compare factors to evaluate fracture toughness, maximum load, equivalent-fracture strain and fracture energy were applied. In the load rate of 0.2mm/min, fracture toughness value using rotation speed of 1000rpm and feed rate of 330mm/min was most excellent of other conditions, but it was poorest in the load rate of 2mm/min.