• 마이크로전자및패키징학회지
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• 제16권2호
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• pp.1-9
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• 2009

Conductive adhesives have recently received a lot of focus and attention from the researchers in electronics industry as a potential substitute to lead-containing solders. Numerous studies have shown that the conductive adhesives have many advantages over conventional soldering such as environmental friendliness, finer pitch feasibility and lower temperature processing. This review focuses on the recent research trends on the reliability and property evaluation of anisotropic and non-conductive films that interconnect the integrated circuit component to the printed circuit board or other types of substrate. Major topics covered are the conduction mechanism in adhesive interconnects; mechanical reliability; thermo-mechanical-hygroscopic reliability and electrical performance of the adhesive joints. This review article is aimed at providing a better understanding of adhesive interconnects, their principles, performance and feasible applications.

• Journal of Welding and Joining
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• 제24권6호
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• pp.21-27
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• 2006

This study was focused on the evaluation of the thermo-mechanical board-level reliability of Pb-bearing and Pb-free surface mount assemblies. The composition of Pb-bearing solder was a typical Sn-37Pb and that of Pb-free solder used in this study was a representative Sn-3.0Ag-0.5Cu in mass %. Thermal shock test was chosen for the reliability evaluation of the solder joints. Typical $Cu_6Sn_5$ intermetallic compound (IMC) layer was formed between both solders and Cu lead frame at the as-reflowed state, while a layer of $Cu_3Sn$ was additionally formed between the $Cu_6Sn_5$ and Cu lead frame during the thermal shock testing. Thickness of the IMC layers increased with increasing thermal shock cycles, and this is very similar result with that of isothermal aging study of solder joints. Shear test of the multi layer ceramic capacitor(MLCC) joints was also performed to investigate the degradation of mechanical bonding strength of solder joints during the thermal shock testing. Failure mode of the joints after shear testing revealed that the degradation was mainly due to the excessive growth of the IMC layers during the thermal shock testing.

• 대한기계학회논문집A
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• 제33권4호
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• pp.380-387
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• 2009

The reliability concerns of solder interconnections in flip chip PBGA packages are produced mainly by the mismatch of coefficient of thermal expansion(CTE) between the module and PCB. Finite element analysis has been employed extensively to simulate thermal loading for solder joint reliability and deformation of packages in electronic packages. The objective of this paper is to study the thermo-mechanical behavior of FC-PBGA package assemblies subjected to temperature change, with an emphasis on the effect of the finite element model, material models and temperature conditions. Numerical results are compared with the experimental results by using $moir{\acute{e}}$ interferometry. Result shows that the bending displacements of the chip calculated by the finite element analysis with viscoplastic material model is in good agreement with those by $moir{\acute{e}}$ inteferometry.

• 마이크로전자및패키징학회지
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• 제10권4호
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• pp.1-8
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• 2003

고감도 모아레 간섭계를 이용하여 세라믹 ball grid array 패키지 결합체의 열-기계적 거동을 분석하였다. 한 온도 사이클의 선택된 몇 개의 온도 단계에서 모아레 간섭무늬를 기록하고 해석하였다. 패키지 결합체의 온도변화에 따른 전체적인 변형과 국부적인 변형거동을 정량적으로 나타내었고, 패키지의 굽힘변형과 맨 바깥쪽 솔더볼의 전단변형률에 대한 거동을 토의하였다. 높은 온도에서는 저온 융점 솔더의 응력완화로 인하여 심각한 비선형 거동이 발생되었으며. 솔더볼의 변형을 해석한 결과 높은 온도에서 저온용융 솔더부에 비탄성 변형이 축적되었음을 알 수 있었다.

• International Journal of Automotive Technology
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• 제1권2호
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• pp.79-87
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• 2000

Analytical approach was followed in this work under both the steady state and transient operating conditions to find optimum boundary conditions, where the optically accessible quartz engine can run safely without breaking. Temperature and stress distribution was predicted by FEM analysis. In order to validate thermal boundary condition, model reliability and constraint, outside cylinder temperature was measured and previous study was also followed up numerically. To reduce thermal stress level, three types of outside cooling (natural, moderate forced and intensive forced convection) were considered. Effects of clamping force and combustion pressure were conducted to investigate mechanical stress level. Cylinder thickness, was changed to fine the optimum cylinder thickness. The versatile results achieved from this work can be basic indication, which is capable of causing a sudden quartz cylinder breaking during fired operation.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.40-45
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• 2008

본 연구는 항공구조재로 널리 사용되고 있는 AISI 304강에 대한 상온 및 고온 인장특성을 신뢰성 기법을 이용하여 실험한 결과를 정리한 것이다. 인장실험은 ASTM 규정에 의하여 수행하였고, 정규확률지를 이용하여 항공구조설계 시 적용할 수 있는 A-Basis 및 B-Basis 강도를 평가하는 신뢰성 해석을 수행하였다.

• Smart Structures and Systems
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• 제26권6호
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• pp.703-720
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• 2020

This paper investigates the safety of the wind turbine blade against excessive deformation. For this purpose, the performance of the blade in the along-wind direction is improved by longitudinal stiffener made of shape memory alloy. The rationale behind the selection of this smart material is due to its ability to offer excellent thermo-mechanical behaviour at low strain. Here, Liang-Roger model is adopted for vibration control, and the super-elastic effects are utilised for blade stiffening. Turbulent wind fields are generated at the hub height using TurbSim and the corresponding loads are evaluated using blade element momentum theory. An efficient switching algorithm is developed along with performance curves that enable the designer to select an optimal mode of heating depending upon the operational scenario. Numerical results presented in this paper clearly demonstrate the performance envelope of the proposed stiffener and its influence on the reliability of the blade.

• 반도체디스플레이기술학회지
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• 제18권4호
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• pp.149-153
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• 2019

The technology of electronic packaging among semiconductor technologies is evolving as an axis of the market in its own field beyond the simple assembly process of the past. In the field of electronic packaging technology, the packaging of power modules plays an important role for green electric vehicles. In this power module packaging, the thermal reliability is an important factor, and silicon nitride plays an important part of package substrates, Silicon nitride is a compound that is not found in nature and is made by chemical reaction between silicon and nitrogen. In this study, this core material, silicon nitride, was fabricated by reaction bonded silicon nitride. The fabricated silicon nitride was studied for thermo-mechanical properties, and through this, the structure of power module packaging was made using reaction bonded silicon nitride. And the characteristics of stress were evaluated using finite element analysis conditions. Through this, it was confirmed that reaction bonded silicon nitride could replace the silicon nitride as a package substrate.

• 대한기계학회논문집A
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• 제24권8호
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• pp.1968-1799
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• 2000

A warpage analysis program has been developed for fiber-reinforced injection molded parts. The warpage is predicted from the residual stress and anisotropic thermo-mechanical properties coupled with fiber orientation in the integrated injection molding simulation. A simple elastic model is used for the calculation of thermally and pressure-induced residual stresses which are employed as the initial conditions in the structural analysis. To improve the reliability of warpage analysis, a new triangular flat shell element superimposing well-known efficient plate bending and membrane element is presented. The numerical examples address the necessity to use anisotropic models for fiber-reinforced materials and show that predicted warpage is in good agreement with experimentally measured one.

• 마이크로전자및패키징학회지
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• 제17권2호
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• pp.21-28
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• 2010

본 논문에서는 온도 사이클이 진행되는 동안 비선형 거동과 크립 거동을 보이는 FC-PBGA 패키지 솔더볼의 변형거동을 알아보기 위하여 시간에 종속하는 거동을 적용 시킬 수 있는 점소성 모델과 크립 모델에 대하여 유한요소해석을 수행하였다. 유한요소해석 결과의 신뢰성을 평가하기 위하여 무아레 간섭계를 이용하여 온도변화에 따른 열변형 실험을 수행하였다. 전체적인 굽힘변위는 Anand 모델과 변형률 분리 모델 모두 실험결과와 잘 일치하였으나 솔더볼의 변형률은 Anand 모델의 경우 큰 차이를 보이고 변형률 분리 모델의 경우 상당히 일치하는 계산결과를 얻었다. 따라서 본 논문에서는 변형률 분리 모델을 이용하여 시간에 종속하는 FC-PBGA 패키지 솔더볼의 크립 거동을 검토하였다. 솔더를 포함한 패키지에 온도변화가 생길 때 고온에서는 시간이 지남에 따라 크립 거동에 의해 솔더의 응력이 점차 완화되는 현상을 나타내고 있음을 알 수 있었다.