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무연 솔더 접합부을 갖는 플립칩에서의 언더필 및 범프 피치 변화에 의한 열 피로 수명 예측 해석
김성걸,김주영,Kim, Seong-Keol,Kim, Joo-Young 한국생산제조학회 2010 한국생산제조학회지 Vol.26 No.2
This paper describes the thermal fatigue life prediction models for 95.5Sn-4.0Ag-0.5Cu solder joints of Flip chip package considering Under Bump Metallurgy(UBM). A 3D Finite element slice model was used to simulate the viscoplastic behavior of the solder. For two types of solder bump pitches, simulations were analyzed and the effects of underfill packages were studied. Consequently, it was found out that solder joints with underfill had much better fatigue life than solder joints without underfill, and solder joints with $300{\mu}m$ bump pitch had a longer thermal fatigue life than solder joints with $150{\mu}m$ bump pitch. Through the simulations, flip chip with lead-free solder joints should be designed with underfill and a longer bump pitch.
무연 솔더 접합부을 갖는 플립칩에서의 언더필 및 범프 피치 변화에 의한 열 피로 수명 예측 해석
김성걸(Kim Seong Keol),김주영(Kim Joo-Young) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.2
This paper describes the thermal fatigue life prediction models for 95.5Sn-4.0Ag-0.5Cu solder joints of Flip chip package considering Under Bump Metallurgy(UBM). A 3D Finite element slice model was used to simulate the viscoplastic behavior of the solder. For two types of solder bump pitches, simulations were analyzed and the effects of underfill packages were studied. Consequently, it was found out that solder joints with underfill had much better fatigue life than solder joints without underfill, and solder joints with 300㎛ bump pitch had a longer thermal fatigue life than solder joints with 150㎛ bump pitch. Through the simulations, flip chip with lead-free solder joints should be designed with underfill and a longer bump pitch.
김성걸(Kim Seong Keol) 한국생산제조학회 2007 한국생산제조학회지 Vol.16 No.3
Generally, the integrated system using ion beam consists of 4 major parts, which are SEM, FIB, nano stage, and chamber. Among them, the nano stage and the chamber are designed and manufactured. The whole systems are integrated. Also, FE models are built to perform modal analyses of each part and the whole integrated system with a commercial program. Through these analyses, it is found that each part and the integrated system are very safe against vibrations including external excitations from ground and any others, because their natural frequencies are much larger than frequencies of external excitations. Also, isolation of ground induced vibration is considered.
언더필을 고려한 Sn-1.0Ag-0.5Cu 조성의 솔더볼을 갖는 플립칩에서의 보드레벨 낙하 및 진동해석
김성걸(Seong-Keol Kim),임은모(Eun-Mo Lim) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.2
Drop simulations of the board level in the flip chips with solder joints have been highlighted for years, recently. Also, through the study on the life prediction of thermal fatigue in the flip chips considering underfill, its importance has been issued greatly. In this paper, dynamic analysis using the implicit method in the Finite Element Analysis (FEA) is carried out to assess the factors effecting on flip chips considering underfill. The design parameters are size and thickness of chip, and size, pitch and array of solder ball with composition of Sn1.0Ag0.5Cu. The board systems by JEDEC standard is modeled with various design parameter combinations, and through these simulations, maximum yield stress and strain at each chip are shown at the solder balls. Modal analysis is simulated to find out the relation between drop impact and vibration of the board system.
Sn-3.0Ag-0.5Cu 및 Sn-1.0Ag-0.5Cu 조성의 솔더 볼을 갖는 플립칩에서의 보드레벨 낙하 해석
김성걸(Seong-Keol Kim) 한국생산제조학회 2011 한국생산제조학회지 Vol.20 No.2
Recently, mechanical reliabilities including a drop test have been a hot issue. In this paper, solder balls with new components which are Sn-3.0Ag-0.5Cu and Sn-1.0Ag-0.5Cu-0.05N are introduced, and board level drop test for them are conducted under JEDEC standard in which the board with 15 flip chips is dropped as 1,500g acceleration during 0.5ms. The drop simulations are studied by using a implicit method in the ANSYS LS-DYNA, and modal analysis is made. Through both analyses, the solder balls with new components are evaluated under the drop. It is found that the maximum stress of each chip is occurred between the solder ball and the PCB, and the highest value among the maximum stresses in the chips is occurred on the chip nearest to fixed holes on the board in the drop tests and simulations.
플립칩의 매개변수 변화에 따른 보드레벨의 동적신뢰성평가
김성걸(Seong Keol Kim),임은모(Eun Mo Lim) 한국생산제조학회 2011 한국생산제조학회지 Vol.20 No.5
Drop impact reliability assessment of solder joints on the flip chip is one of the critical issues for micro system packaging. Our previous researches have been showing that new solder ball compositions of Sn-3.0Ag-0.5Cu has better mechanical reliability than Sn-1.0Ag-0.5Cu. In this paper, dynamic reliability analysis using Finite Element Analysis (FEA) is carried out to assess the factors affecting flip chip in drop simulation. The design parameters are size and thickness of chip, and size, pitch and array of solder ball with composition of Sn1.0Ag0.5Cu. The board systems by JEDEC standard including 15 chips, solder balls and PCB are modeled with various design parameter combinations, and through these simulations, maximum yield stress and strain at each chip are shown at the solder balls. It is found that larger chip size, smaller chip array, smaller ball diameter, larger pitch, and larger chip thickness have bad effect on maximum yield stress and strain at solder ball of each chip.
도시철도 차량의 차륜답면과 제륜자간 제동 마찰열에 관한 연구
김성걸(Seong Keol Kim),윤천주(Cheon Joo Yoon),구병춘(Byeong Choon Goo) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.6
Wheel treads of E.M.U. are usually under a heavy thermal load by brake frictional heat between wheel and brake shoe and damaged by repeated thermal and mechanical loads. To examine the cause of wheel tread damage of E.M.U.'s in service running, a systematic approach has been used. This study is composed of three parts. Frictional heat analysis was conducted in the first part by finite element method. Two kinds of brake shoes in service were considered. In the second part, experimental study was carried out on a brake dynamometer. Temperatures were measured for the two brake shoes. And experimental study in service running E.M.U.'s was performed. Wheel and brake shoe temperatures were measured by using thermocouples and temperature indicating strips. Finally metallurgical characteristics were examined by a SEM/EDS and the cause of the wheel damage was analyzed. It seems that aggregated ferrous component is a main cause of the wheel tread damage.
김성걸(Seong Keol Kim) 한국자동차공학회 2005 한국 자동차공학회논문집 Vol.13 No.4
Analyses of dynamic models which were one and two degrees of freedom, and had the nonlinear springs and dampings with certain polynomial functions were performed from SIMULINK in MATLAB. Those consisted of 12 programs and were built on the basis of the preceding programs for the linear dynamic simulations. However the programs for the nonlinear simulations were quite different from those for the linear ones, and showed the results of the analyses in real time with animating. It was found that the programs would help us to solve any kind of nonlinear dynamic simulation with one and two degrees of freedom. Especially, the simulations for 1 DOF system with cubic nonlinear spring force showed the results for Duffing's equation, of which phenomena were jump-up and jump-down. It will be applied to the dynamic simulation of the car seat vibration with a passenger, of which model has the equivalent nonlinear springs and is two degrees of freedom.