Solder joint reliability is of great concern to semiconductor and electronic product manufacturers. Due to rapid advancements in the electronic industry, packages with fine pitch ball grid array have been increasingly used in portable electronic devices. The mechanical shock resulting from mishandling during transportation or custom usage may lead to malfunction of product. A Joint Electron Device Engineering Council (JEDEC) standard (JESD22‐B111) for a board‐level drop test of handheld electronic products was released to specify the drop test procedure and conditions in 2003. The purpose of this paper is to design and analyze the performance of a drop test apparatus created in an in‐house laboratory in terms of research basis. The specified impact shock with a sine wave accompanied by peak acceleration and pulse duration is a core requirement. The impact pulse is a complex function of various tester parameters. However, this is a unique characteristic based on the infrastructure design of each drop tester. Once the main frame of the drop tester is established, the drop height, strike surface material, and thickness are the major factors to evaluate the performance of drop tester. Therefore, many time‐consuming experimental trial‐and‐error steps are required to calibrate and characterize a drop tester to achieve the required impact pulse. The most serious conditions B, G and H are achieved, also for condition A, which satisfies the JESD22‐B111 test conditions. To provide design guidelines, the dynamic simulation using finite element model by ANSYS LS‐DYNA code was performed in terms of drop height, strike surface material, and thickness. This study observed that () the peak acceleration and pulse duration are significantly affected by strike surface thickness; () the peak acceleration is strongly affected by strike surface modulus, but less so on the pulse duration; () the drop height affects the peak acceleration, but is insignificant on the pulse duration. The results between experiment and simulation are well correlated at certain levels. An empirical relationship is developed to determine the different design parameters of peak acceleration and pulse duration. In real applications, the designed parameters that can be varied to achieve the desired impact pulse are strike surface modulus and thickness because the drop height is standard.

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In the first half of the 20th century, a lot of important phenomena and ideological trends appeared in the history of China's fine arts development, including the ideas of promoting aesthetic education and saving the country with education. This paper analyses the role of Xiting Public Junior Art Normal College in promoting the new aesthetic education of Quanzhou, in an attempt to illustrate his influence and importance, and explain why the school failed, from the political, economic and social perspectives.

Due to the high speed and high I/O count requirements for semiconductor packages, thousands of soldered interconnections are indispensable, and this situation renders traditional finite element method (FEM) analysis a formidable challenge. This paper presents a 3D-equivalent global model and local submodeling technique to investigate board-level solder joint reliability under cyclic temperature loading. The equivalent global model is capable of addressing critical solder failure locations. An individual local solder ball is used to predict the number of cycles to failure. The high performance flip-chip ball grid array (HFCBGA) package case was studied with the provided experimental data. According to FEM results, the predicted solder ball life is close to that observed experimentally. Therefore, the global-to-local modeling technique can be concluded to provide an efficient methodology for evaluating very high pin count HFCBGA package reliability.