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FEM에 의한 일반냉연강판 및 고장력강판의 점용접 피로수명해석
유효선(Hyosun Yu),양성모(Sungmo Yang),강희용(Heeyong Kang),김홍건(Honggun Kim),김규상(Kyusang Kim) 한국생산제조학회 2008 한국생산제조학회지 Vol.17 No.5
Cold rolled and high strength steel were used for vehicle bodys to satisfy environmental regulation and improve fuel ratio. This paper presented a method for determining the fatigue life of cold rolled steel sheet EZNCEN and high strength steel sheet HS40R spot weldment used in vehicles. We can estimate the fatigue life of the spot weldments from the MSC/FATIGUE using the finite element method. The maximum load is found in the nugget part of both surfaces. The cold rolled steel and the high strength steel showed the maximum stress 746㎫ and 730㎫ in the effective nugget part when the weld current was 8KA and 7KA, respectively. Also the some weld current of the cold rolled steel and high strength steel is applied, the fatigue life of high strength steel is obtained about four times longer han the cold rolled steel.
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 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.
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.
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.
Sn-4Ag계 Pb-free 솔더 접합부의 Cu 함량에 따른 접합강도 특성평가
하벼리(Byeori Ha),유효선(Hyosun Yu),양성모(Sungmo Yang) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
The evaluation on reliability of environment-friendly Pb-free solder and solder joints is very important. This study compared the shear strength of two different plates(Cu and Ni plate). Also, shear strength of joints of Sn-37Pb solder and Sn-Ag solder alloy with different Cu contents(0, 0.5, 1 wt.%) have been studied. The shear strength tests on various reflow time are performed at 30 and 50℃. 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.