Stress-strain study of QFN solder joints with different structural parameters under random vibration loading

Author(s):  
Maolin Li ◽  
Chun-yue Huang ◽  
Zhuo Wang ◽  
Wei Wei
2019 ◽  
Vol 95 ◽  
pp. 58-64 ◽  
Author(s):  
Jiang Xia ◽  
Lin Yang ◽  
Qunxing Liu ◽  
Qi Peng ◽  
LanXian Cheng ◽  
...  

Author(s):  
Tae-Yong Park ◽  
Hyun-Ung Oh

Abstract To overcome the theoretical limitations of Steinberg's theory for evaluating the mechanical safety of the solder joints of spaceborne electronics in a launch random vibration environment, a critical strain-based methodology was proposed and validated in a previous study. However, for the critical strain-based methodology to be used reliably in the mechanical design of spaceborne electronics, its effectiveness must be validated under various conditions of the package mounting locations and the first eigenfrequencies of a printed circuit board (PCB); achieving this validation is the primary objective of this study. For the experimental validation, PCB specimens with ball grid array packages mounted on various board locations were fabricated and exposed to a random vibration environment to assess the fatigue life of the solder joint. The effectiveness of the critical strain-based methodology was validated through a comparison of the fatigue life of the tested packages and their margin of safety, which was estimated using various analytical approaches.


Author(s):  
Shao-Dong Wu ◽  
De-Guang Shang ◽  
Lin-Xuan Zuo ◽  
Lin-Feng Qu ◽  
Song-Guang Wang ◽  
...  

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1285
Author(s):  
Wentao He ◽  
Shaoping Wang ◽  
Chao Zhang ◽  
Xi Wang ◽  
Di Liu

The service life of mechanical face seals is related to the lubrication and wear characteristics. The stable analytical methods are commonly used, but they cannot address effects of random vibration loading, which, according to experimental studies, are important factors for lubrication and wear of mechanical face seals used in air and space vehicles. Hence, a dynamic model for mechanical face seals is proposed, with a focus on the effects of random vibration loading. The mechanical face seal in the axial direction is described as a mass-spring-damping system. Spectrum analysis specified for random vibration is then performed numerically to obtain the response power spectral density (PSD) of the mechanical face seal and calculate the root mean square (RMS) values under random vibration conditions. A lumped parameter model is then developed to examine how dynamic parameters such as stiffness and damping affect the lubrication regimes of mechanical face seals. Based on the dynamic model and Archard wear equation, a numerical wear simulation method is proposed. The results elucidated that the increase of input acceleration PSDs, the decrease of axial damping, and the increase of axial stiffness lead to the probability of the mechanical face seal operating under full film lubrication regime increase and finally the decrease of wear. This research provides a guideline for improving the adaptability of mechanical face seals under random vibration environments.


2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Feng Wang ◽  
Fangfang Zhang ◽  
Qixiang Huang ◽  
Mohammad Salmani

Purpose The purpose of this paper is to propose a method with capability of short-time implementation. Design/methodology/approach This paper was directed using both experimental tests and simulations to propose a comprehensive method for lifetime estimation of the solder joints. Findings A new method with good agreement with experimental tests has been proposed. Originality/value It is confirmed that paper is original.


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