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Fatigue life estimation of FBGA memory modules under harmonic excitation
Yusuf Cinar,Kyoungwon Seo,Gunhee Jang,Jaeseok Jang,Changwoo Koo 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
This paper predicts the fatigue life of fine-pitch ball grid array (FBGA) solder joints in memory modules due to harmonic excitation by the experiments and the finite element method. A global-local modeling technique was used in finite element simulation. A finite element model of the memory module with simplified solder joints was developed as a global model, and the natural frequencies and modes were calculated and verified by experimental modal testing. Displacement variations were calculated from the global model due to vibration excitation using the mode superposition method. A local model with detailed solder joints was developed in order to calculate stress magnitude concentrated on solder joints of the memory module under vibration. Stress versus life (S-N) curve was developed for memory modules under various vibration levels to derive solder material fatigue constants. Then the fatigue life of the memory module was determined by using the Basquin equation and Miner’s rule. It was experimentally verified that predicted fatigue life of the memory module under cumulative damage conditions matches with experimental results with reasonable accuracy.
Fatigue life estimation of FBGA memory device under vibration
Yusuf Cinar,장건희 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.1
This paper predicts the fatigue life of fine-pitch ball grid array (FBGA) solder joints in memory devices due to harmonic excitationthrough experiments and finite element analysis. Finite element models of the memory device with simplified solder joints and with detailedsolder joints were developed as a global model and a local model, respectively. A global-local modeling technique was used in thefinite element simulation to calculate the stress magnitude of solder joints in the memory device under vibration. Stress versus life (S-N)curve was generated for the memory devices under various vibration levels to derive the fatigue constants of solder material. The fatiguelife of the memory device was then determined by using the Basquin equation and Miner’s rule. It was experimentally verified that thepredicted fatigue life of the memory device under cumulative damage conditions matches the experimental results within reasonable accuracy.
반복적인 굽힘에 따른 FBGA 메모리 모듈의 피로 수명 예측
서경원(Kyoungwon Seo),유수프 츠나르(Yusuf Cinar),장건희(Gunhee Jang),장재석(Jaeseok Jang),구창우(Changwoo Koo) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
In this research, the fatigue life of fine-pitch ball grid array (FBGA) solder joints in memory modules was predicted by the bending experiment and the finite element analysis. Four-point bending test was performed by JEDEC standard to determine fatigue life of a memory module with five packages. Finite element model of the memory module was developed and analyzed under various displacement levels by using direct integration method. Strain under cyclic bending was measured and compared with simulation results for validation of the finite element model of the memory module. A global-local modeling technique was used in finite element simulation to calculate the strain response of the solder joints, and Coffin-Manson equation was developed by experimental and simulation methods. Then, the fatigue life of memory modules was predicted under cumulative damage condition by using the Miner’s rule and compared with experimental results. Experimental results show that predicted fatigue life of the memory module matches with experimental results closely.
레이저 프린터에 사용되는 폴리곤 미러 스캐너 모터 주위의 유동 해석을 통한 공력소음 저감
정연하(Yeonha Jung),장건희(Gunhee Jang),김명규(Myunggyu Kim),Yusuf Cinar 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
This paper calculates the air flow around the polygon mirror scanner motor of a laser printer operating at high speed by using a commercial tool. Simulation result is verified by measuring the velocity of air flow around the polygon mirror with a hot-wire anemometer. The frequency spectrum of the air flow around the polygon mirror match with that of aero-acoustic noise, and it confirms that significant amount of the discrete peaks and broadband of aero-acoustic noise are originated from the air flow around the polygon mirror. This paper proposes an air block to reduce the air flow around the polygon mirror, and it shows experimentally that the proposed air block reduces not only the air flow but also the discrete and broadband of aero-acoustic noise.