The flip chip package is a kind of advanced electri ca l packages. Due to the requirement of miniaturization, lower weight, higher dens ity and higher performance in the advanced electric package, it is expected that ...The flip chip package is a kind of advanced electri ca l packages. Due to the requirement of miniaturization, lower weight, higher dens ity and higher performance in the advanced electric package, it is expected that flip chip package will soon be a mainstream technology. The silicon chip is dir ectly connected to printing circuit substrate by SnPb solder joints. Also, the u nderfill, a composite of polymer and silica particles, is filled in the gap betw een the chip and substrate around the solder joints to improve the reliabili ty of solder joints. When flip chip package specimen is tested with thermal cycl ing, the cyclic stress/strain response that exists at the underfill interfaces and solder joints may result in interfacial crack initiation and propagation. Therefore, the chip cracking and the interfacial delamination between underfill and chip corner have been investigated in many studies. Also, most researches h ave focused on the effect of fatigue and creep properties of solder joint induce d by the plastic strain alternation and accumulation. The nuderfill must have lo w viscosity in the liquid state and good adhesion to the interface after solidif ying. Also, the mechanical behavior of such epoxy material has much dependen ce on temperature in its glass transition temperature range that is usually cove red by the temperature range of thermal cycling test. Therefore, the materia l behavior of underfill exists a significant non-linearity and the assumption o f linear elastic can lack for accuracy in numerical analysis. Through numerical analysis, this study had some comparisons about the effect of linear and non -linear properties of underfill on strain behaviors around the interface of fli p chip assembly. Especially, the deformation tendency inside solder bumps could be predicted. Also, it is worthily mentioned that we have pointed out which comp onent of plastic strain, thus, either normal or shear, has dominant influence to the fatigue and creep of solder bump, which have not brought up before. About the numerical analysis to the thermal plastic strain occurs in flip chip i nterconnection during thermal cycling test, a commercial finite element software , namely, ANSYS, was employed to simulate the thermal cycling test obeyed by MIL-STD-883C. The temperatures of thermal cycling ranged from -55 ℃ to 125 ℃ with ramp rate of 36 ℃/min and a dwell time of 25 min at peak temperature. T he schematic drawing of diagonal cross-section of flip chip package composed of FR-4 substrate, silicon chip, underfill and solder bump was shown as Fig.1. Th e numerical model was two-dimensional (2-D) with plane strain assumption and o nly one half of the cross-section was modeled due to geometry symmetry. The dim ensions and boundary conditions of numerical model were shown in Fig.2. The symm etric boundary conditions were applied along the left edge of the model, and the left bottom corner was additional constrained in vertical direction to prevent body motion. The finite element meshes of overall and local numerical model was shown as Fig.3. In this study, two cases of material model were used to describe the material behavior of the underfill: the case1 was linear elastic model that assumed Young’s Modulus (E) and thermal expansion coefficient (CTE) were consta nt during thermal cycling; the case2 was MKIN model (in ANSYS) that had nonlinea r temperature-dependent stress-strain relationship and temperature-dependent CTE. The material model applied to the solder bump was ANAND model (in ANSYS) th at described time-dependent plasticity phenomenon of viscoplastic material. Bot h the FR-4 substrate and silicon chip were assumed as temperature-independent elastic material; moreover, FR-4 substrate is orthotropic while silicon chip is isotropic. From the comparison between numerical results of linear and nonlinear material a ssumption of underfill, (i.e. case1 and case2), the quantities of plastic strain around the interconnection from case1 are higher than that in case2. Thus, the linear展开更多
OBJECTIVE To investigate the effect of rhynchophylline on behavior of zebrafish with Alzheimer disease induced by AlCl3.METH⁃ODS Take a video of the zebrafish before train⁃ing,which is convenient for judging whether t...OBJECTIVE To investigate the effect of rhynchophylline on behavior of zebrafish with Alzheimer disease induced by AlCl3.METH⁃ODS Take a video of the zebrafish before train⁃ing,which is convenient for judging whether the zebrafish has been trained successfully.Then,the zebrafish were trained for 7 d.The 60 zebraf⁃ish that were successfully trained were randomly divided into 6 groups:normal group,model group,positive group,low-dose rhynchophylline group,middle-dose group,and high-dose group.The normal group was video-recorded,while the model group,positive group,low-dose group,middle-dose group,and high-dose group were given AlCl3 for modeling.After that,the model group was videotaped,and the other groups were given drug intervention.Both the positive group and the rhynchophylline administration group were administered for 6 d,and finally all the administration groups were videotaped.After all the video is finished,the behavioral analysis software smart 3.0 was used for behavioral anal⁃ysis,and conclusions are drawn by analyzing the data.RESULTS The data of the 6 groups of zebrafish staying in the red short arm area were used for comparative analysis:there was a signif⁃icant difference between the normal group and the model group(P<0.05),the model group and the positive group,and the middle-dose group of rhynchophylline There are significant differences in the high-dose group(P<0.05).Comparative analysis with the data of the percentage of zebraf⁃ish in the red short arm area of the 6 groups:the normal group and the model group are signifi⁃cantly different(P<0.05),There were significant differences between the model group and posi⁃tive group,the dose of the rhynchophylline administration group high-dose group and the middle-dose group(P<0.05).Comparing the data of the swimming distance of the 6 groups of zebrafish in the red short arm area:the normal group and the model group are not significantly different(P>0.05),while the model group is only significantly different from the high-dose group(P<0.05).However,the comparison of the percentage of zebrafish swimming distance in the red short arm area of the 6 groups of data:the normal group and the model group are signifi⁃cantly different(P<0.05),the model group and the positive group,and the rhynchophylline administration group There were significant differ⁃ences between the dose group and the high-dose group(P<0.05).CONCLUSION Rhynchophyl⁃line can improve the behavior of zebrafish with Alzheimer disease.展开更多
The household drill is named 90 Degree, designed by Industrial Design Pilot Program Center(Hereinafter referred to as IDPPC) of Luxun Academy of Fine Arts(Hereinafter referred to as LAFA), which is the only national p...The household drill is named 90 Degree, designed by Industrial Design Pilot Program Center(Hereinafter referred to as IDPPC) of Luxun Academy of Fine Arts(Hereinafter referred to as LAFA), which is the only national pilot program center in Chinese industrial design field. 90 Degree is designed for home environment, it helps inexperience users, such as women and the elderly, complete the operation easily, and it makes sure that safe operation and assistance users solve the precise punching, location, storage trash and other operations. According to research among users who can understand or manipulate a drill, the designers find problems of users from the user central perspective, and then they integrate product innovative design methods to propose solutions. When the designers intend to design 90 Degree, they attempt using the user behavior record and analysis system, and start ergonomics study in subjects by double hands operation analysis, using gesture analysis, details of work analysis, time and motion study, etc; meanwhile taking advantages of user experience analysis, behavior intention analysis to do user subjective perceptual evaluation. The functions, structure, shape, color, material, details of 90 Degree should be consistent with the standard of usability evaluation. There are two characteristics in 90 Degree, the first one is a transparent cover installed in front of the drill, which can collect the dust, rubbish when drilling and keep the work environment clean. So it is applicable for households. When the transparent cover of the drill is removed, it also can be used as a normal hand drill; the second one is the shape of 90 Degree makes it and the operating surface fitting together, thus enhancing the stability in operation, so it is best for inexperienced users. When 90 Degree contacts with the operating surface, it can emit the laser ray which helps the user to punch accurately, and make array punch more easily. After obtaining the data, charts, creating Shadow observation by the designers, they make a comprehensive evaluation on research results; verification advantages of 90 Degree meet the requirement of usability, reducing operating failure rate; and increasing safety factors. 90 Degree, in 2011, wined German Red Dot Design Award, which had become a representative excellent design example to resolve several drilling difficulties. The designers introduce ergonomics theory into design practice, and use scientific program and methods to evaluate the products which is useful to the development and promotion of products.展开更多
文摘The flip chip package is a kind of advanced electri ca l packages. Due to the requirement of miniaturization, lower weight, higher dens ity and higher performance in the advanced electric package, it is expected that flip chip package will soon be a mainstream technology. The silicon chip is dir ectly connected to printing circuit substrate by SnPb solder joints. Also, the u nderfill, a composite of polymer and silica particles, is filled in the gap betw een the chip and substrate around the solder joints to improve the reliabili ty of solder joints. When flip chip package specimen is tested with thermal cycl ing, the cyclic stress/strain response that exists at the underfill interfaces and solder joints may result in interfacial crack initiation and propagation. Therefore, the chip cracking and the interfacial delamination between underfill and chip corner have been investigated in many studies. Also, most researches h ave focused on the effect of fatigue and creep properties of solder joint induce d by the plastic strain alternation and accumulation. The nuderfill must have lo w viscosity in the liquid state and good adhesion to the interface after solidif ying. Also, the mechanical behavior of such epoxy material has much dependen ce on temperature in its glass transition temperature range that is usually cove red by the temperature range of thermal cycling test. Therefore, the materia l behavior of underfill exists a significant non-linearity and the assumption o f linear elastic can lack for accuracy in numerical analysis. Through numerical analysis, this study had some comparisons about the effect of linear and non -linear properties of underfill on strain behaviors around the interface of fli p chip assembly. Especially, the deformation tendency inside solder bumps could be predicted. Also, it is worthily mentioned that we have pointed out which comp onent of plastic strain, thus, either normal or shear, has dominant influence to the fatigue and creep of solder bump, which have not brought up before. About the numerical analysis to the thermal plastic strain occurs in flip chip i nterconnection during thermal cycling test, a commercial finite element software , namely, ANSYS, was employed to simulate the thermal cycling test obeyed by MIL-STD-883C. The temperatures of thermal cycling ranged from -55 ℃ to 125 ℃ with ramp rate of 36 ℃/min and a dwell time of 25 min at peak temperature. T he schematic drawing of diagonal cross-section of flip chip package composed of FR-4 substrate, silicon chip, underfill and solder bump was shown as Fig.1. Th e numerical model was two-dimensional (2-D) with plane strain assumption and o nly one half of the cross-section was modeled due to geometry symmetry. The dim ensions and boundary conditions of numerical model were shown in Fig.2. The symm etric boundary conditions were applied along the left edge of the model, and the left bottom corner was additional constrained in vertical direction to prevent body motion. The finite element meshes of overall and local numerical model was shown as Fig.3. In this study, two cases of material model were used to describe the material behavior of the underfill: the case1 was linear elastic model that assumed Young’s Modulus (E) and thermal expansion coefficient (CTE) were consta nt during thermal cycling; the case2 was MKIN model (in ANSYS) that had nonlinea r temperature-dependent stress-strain relationship and temperature-dependent CTE. The material model applied to the solder bump was ANAND model (in ANSYS) th at described time-dependent plasticity phenomenon of viscoplastic material. Bot h the FR-4 substrate and silicon chip were assumed as temperature-independent elastic material; moreover, FR-4 substrate is orthotropic while silicon chip is isotropic. From the comparison between numerical results of linear and nonlinear material a ssumption of underfill, (i.e. case1 and case2), the quantities of plastic strain around the interconnection from case1 are higher than that in case2. Thus, the linear
基金National Natural Science Foundation of China(8216140711)Natural Sci⁃ence Foundation of Guangxi Zhuang Autono⁃mous Region(2017GXNSFAA198255)+3 种基金Natural Science Foundation of Guangxi Zhuang Autono⁃mous Region(2018GXNSFBA138028)Guangxi Key Laboratory of Brain and Cognitive Neurosci⁃ence Open Project Funding(GKLBCN-20180105-03)2019 College Student Innovation and En⁃trepreneurship Project Training Plan(201910601038)and the Fourth Training Plan for Thou⁃sands of Young and Mid-aged Mainstay Teach⁃ers in Guangxi Colleges and Universities.
文摘OBJECTIVE To investigate the effect of rhynchophylline on behavior of zebrafish with Alzheimer disease induced by AlCl3.METH⁃ODS Take a video of the zebrafish before train⁃ing,which is convenient for judging whether the zebrafish has been trained successfully.Then,the zebrafish were trained for 7 d.The 60 zebraf⁃ish that were successfully trained were randomly divided into 6 groups:normal group,model group,positive group,low-dose rhynchophylline group,middle-dose group,and high-dose group.The normal group was video-recorded,while the model group,positive group,low-dose group,middle-dose group,and high-dose group were given AlCl3 for modeling.After that,the model group was videotaped,and the other groups were given drug intervention.Both the positive group and the rhynchophylline administration group were administered for 6 d,and finally all the administration groups were videotaped.After all the video is finished,the behavioral analysis software smart 3.0 was used for behavioral anal⁃ysis,and conclusions are drawn by analyzing the data.RESULTS The data of the 6 groups of zebrafish staying in the red short arm area were used for comparative analysis:there was a signif⁃icant difference between the normal group and the model group(P<0.05),the model group and the positive group,and the middle-dose group of rhynchophylline There are significant differences in the high-dose group(P<0.05).Comparative analysis with the data of the percentage of zebraf⁃ish in the red short arm area of the 6 groups:the normal group and the model group are signifi⁃cantly different(P<0.05),There were significant differences between the model group and posi⁃tive group,the dose of the rhynchophylline administration group high-dose group and the middle-dose group(P<0.05).Comparing the data of the swimming distance of the 6 groups of zebrafish in the red short arm area:the normal group and the model group are not significantly different(P>0.05),while the model group is only significantly different from the high-dose group(P<0.05).However,the comparison of the percentage of zebrafish swimming distance in the red short arm area of the 6 groups of data:the normal group and the model group are signifi⁃cantly different(P<0.05),the model group and the positive group,and the rhynchophylline administration group There were significant differ⁃ences between the dose group and the high-dose group(P<0.05).CONCLUSION Rhynchophyl⁃line can improve the behavior of zebrafish with Alzheimer disease.
文摘The household drill is named 90 Degree, designed by Industrial Design Pilot Program Center(Hereinafter referred to as IDPPC) of Luxun Academy of Fine Arts(Hereinafter referred to as LAFA), which is the only national pilot program center in Chinese industrial design field. 90 Degree is designed for home environment, it helps inexperience users, such as women and the elderly, complete the operation easily, and it makes sure that safe operation and assistance users solve the precise punching, location, storage trash and other operations. According to research among users who can understand or manipulate a drill, the designers find problems of users from the user central perspective, and then they integrate product innovative design methods to propose solutions. When the designers intend to design 90 Degree, they attempt using the user behavior record and analysis system, and start ergonomics study in subjects by double hands operation analysis, using gesture analysis, details of work analysis, time and motion study, etc; meanwhile taking advantages of user experience analysis, behavior intention analysis to do user subjective perceptual evaluation. The functions, structure, shape, color, material, details of 90 Degree should be consistent with the standard of usability evaluation. There are two characteristics in 90 Degree, the first one is a transparent cover installed in front of the drill, which can collect the dust, rubbish when drilling and keep the work environment clean. So it is applicable for households. When the transparent cover of the drill is removed, it also can be used as a normal hand drill; the second one is the shape of 90 Degree makes it and the operating surface fitting together, thus enhancing the stability in operation, so it is best for inexperienced users. When 90 Degree contacts with the operating surface, it can emit the laser ray which helps the user to punch accurately, and make array punch more easily. After obtaining the data, charts, creating Shadow observation by the designers, they make a comprehensive evaluation on research results; verification advantages of 90 Degree meet the requirement of usability, reducing operating failure rate; and increasing safety factors. 90 Degree, in 2011, wined German Red Dot Design Award, which had become a representative excellent design example to resolve several drilling difficulties. The designers introduce ergonomics theory into design practice, and use scientific program and methods to evaluate the products which is useful to the development and promotion of products.
