我们基于成果导向的工程教育理念,以毕业要求为起点,通过横向分解、纵向分步,反向设计了机械设计系列课程体系,构建了从初步常规设计到综合创新设计的提升平台;并以实际工程项目驱动引领课堂教学,充分利用"互联网+"技术,搭建了课堂教学与实践活动、科技竞赛相融合,线上与线下相融合,以学生为中心的立体化教学系统.多年的探索与实践证明,该体系下的课程教学取得了良好的效果.

随着机器视觉技术的发展,在注塑成型行业得到广泛应用,有利于注塑智能制造技术的发展.首先介绍了机器视觉技术,综述了机器视觉技术在注塑成型加工中的两个主要应用模具监测和产品质量控制,最后对机器视觉技术在注塑成型加工中的应用进行了展望.

An unified viscoplastic constitutive Anand model was utilized to describe the inelastic deformation behavior for SnAgCu solder alloy in PBGA package and to analyze the stress-strain response in the solder joints under thermal cyclic loading.The results demonstrated that the stresses and strains of corner solder joints were higher than those of inner solder balls.The equivalent plastic strain of the solder alloy near the IMC layer increased dynamically due to the properties of the brittle IMC layer.The strain energy represented in the stress-strain hysteresis loop of the IMC solder joints in high stress concentration region was higher than that of non-IMC solder.The simulation results revealed that the IMC layer significantly affected thermal fatigue reliability of the solder joints.The thermal fatigue lifetime using the Anand model was basically consistent with experimental data.

采用ANSYS统一Anand粘塑性本构方程描述SnAgCu焊点非弹性形变.对考虑IMC的PBGA焊点与不考虑IMC的PBGA焊点在温度循环载荷作用下的应力应变响应进行分析比较.结果表明,远离中心位置的外侧焊点承受更大的应力应变;在温度循环加载过程中IMC层积累了较大的应力;由于IMC层的硬脆性材料特性,应力不会通过塑性形变释放,使焊料在高应力IMC界面发生较大的塑性形变;IMC焊点高应力集中区的应力应变迟滞回线所代表的应变能高于不考虑IMC的焊点,导致其热疲劳寿命远低于不考虑IMC的焊点,与实际温度循环试验结果更为接近.

以热弹塑性理论为基础，建立球栅阵列PBGA焊点在回流焊T艺中焊接应力的有限元模型，利用ANSYS的热结构耦合功能，采用生死单元法对sn-Ag-cu焊点回流焊的冷却过程进行数值模拟分析．焊点冷却结晶后的初始阶段，等效应力随温度的降低快速增加，当焊点的温度逐渐降低至室温时，等效应力为最大．结果表明，在回流焊接工艺中，PBGA焊点的裂纹极可能发生在焊料冷却结晶后的初始阶段，在焊点高应力集中区首先开裂，并在应力的作用下沿界面逐渐扩展．对焊料凝固初期冷却速率的控制是减少焊接裂纹产生的有效方法．

Numerous studies of the reliability of solder joints have been performed. Most life prediction models are limited to a deterministic approach. However, manufacturing induces uncertainty in the geometry parameters of solder joints, and the environmental temperature varies widely due to end-user diversity, creating uncertainties in the reliability of solder joints. In this study, a methodology for accounting for variation in the lifetime prediction for lead-free solder joints of ball grid array packages (PBGA) is demonstrated. The key aspects of the solder joint parameters and the cyclic temperature range related to reliability are involved. Probabilistic solutions of the inelastic strain range and thermal fatigue life based on the Engelmaier model are developed to determine the probability of solder joint failure. The results indicate that the standard deviation increases significantly when more random variations are involved. Using the probabilistic method, the influence of each variable on the thermal fatigue life is quantified. This information can be used to optimize product design and process validation acceptance criteria. The probabilistic approach creates the opportunity to identify the root causes of failed samples from product fatigue tests and field returns. The method can be applied to better understand how variation affects parameters of interest in an electronic package design with area array interconnections.

A probabilistic method is utilized to predict solder joint reliability of surface mounting devices.Chip component 0603 is taken as an example.Based on the simplified joint geometry model and Coffin-Manson relation,equations and solutions of thermal fatigue life are established and validated to determine the probability of failure for lead-free solder joints.Uncertainties in the solder's geometry are often related to manufacturing processes,and the ambient temperature varies due to the diversity of end-users.Using the approach,the influence of each uncertainty on the thermal fatigue life is quantified.This information can be used to optimize the product design,establish acceptance criteria for quality control,and predict after-sales product quality.The result shows that the thermal fatigue life of the solder joints decreases significantly with the increase of random variables.The key aspects of the normally distributed random variables,solder joint geometry,H,L and thermal range Δθ are involved to predict the low cycle thermal fatigue life according to the experimental data of small sample with measured standard deviation and mean value.

Solder joints quality is critical to electronic package performance and service life,this problem is more important during the last decade with the switch to surface mount technologies from through-hole assembly.The reliability and manufacturing quality of BGA component solder joints directly impact the product quality.During the BGA processing,the variations of manufacturing process,component and PCB(print circuit board) parameters directly result in the variation of solder joint geometric parameters.In terms of statistical parameters unavoidable introduced by surface mount manufacturing,assembly process,component and PCB,an analytical modeling were developed to predict BGA solder yield performance,identify the relationship of design and process parameters,find the root cause of solder defects,and improvement of process parameters integrated with software simulation was suggested.The approach focused on BGA component solder joint,but the methodology was applicable to other SMT components.

By mathematical statistics based on the manufacturing process variations and variations of component and PCB,using the software of surface Evolver simulation,mode of BGA solder yield predictor was built.Using the mode and simulatrng the solder joint shapes,find the root cause of solder defects identify the relationship of designand process parameters,suggest design improvemet.