共查询到18条相似文献,搜索用时 171 毫秒
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文中首先制作了无铅焊料SAC305的拉伸试样,在不同温度和应变率条件下进行了单轴拉伸试验,研究其力学性能;进行了Anand本构模型的研究和参数拟合分析,通过非线性拟合方法获得了Anand模型的9个参数,应用有限元仿真软件ABAQUS建立模型来预测应力–应变曲线,将其与试验数据曲线相比较,两者结果基本吻合。其次,通过仿真测试对比分析散热器装配预应力对芯片焊点温度循环(以下简称温循)可靠性的影响。基于以上试验和数据拟合得到的Anand模型参数,建立散热器及球形栅格阵列(Ball Grid Array, BGA)器件的四分之一对称三维模型进行模拟,分析有或无散热器两种状态下,模型在?40 ?C ~ 125 ?C温循载荷下的焊点应变,利用coffin-manson公式对焊点寿命进行了预测。仿真及测试结果均表明,应变最大值位于器件角上焊点与芯片接触侧,装配预应力对焊点温循寿命存在影响。 相似文献
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文中采用自动化手段研究了大功率微波芯片共晶焊接技术,分别对影响微波芯片焊接焊透率的预置焊料、温度曲线、氮气保护气氛、摩擦次数等影响因素开展了研究。通过在MoCu 热沉上预置焊料,采用优化的共晶焊接温度曲线,施加一定流量的氮气保护,采用合适的共晶焊接摩擦次数,最终获得了具有良好焊透率的大功率微波芯片共晶焊接模块。焊接位置精度能够控制在(25±5) μm 范围内。文中还完成了焊后大功率微波芯片模块的热循环试验,进行了微波芯片的剪切力测试。试验结果显示共晶焊接焊点剪切力满足GJB 548B—2005 的要求,表明采用优化的工艺参数获得的大功率微波芯片共晶焊接模块具有很高的可靠性。 相似文献
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由于焊点区非协调变形导致的热疲劳失效是倒装芯片封装(包括无铅封装)结构的主要失效形式.到目前为止,仍无公认的焊点寿命和可靠性的评价方法.文中分别采用双指数和双曲正弦本构模型描述SnAgCu焊点的变形行为,通过有限元方法计算焊点累积蠕变应变和累积蠕变应变能密度,进而据此预测倒装芯片封装焊点的热疲劳寿命.通过实验验证,评价上述预测方法的可行性.结果表明,倒装芯片的寿命可由芯片角焊点的寿命表征;根据累积蠕变应变能密度预测的焊点热疲劳寿命比根据累积蠕变应变预测的焊点热疲劳寿命更接近实测数据;根据累积蠕变应变预测的热疲劳寿命比根据累积蠕变应变能密度预测的热疲劳寿命长;采用双指数本构模型时,预测的焊点热疲劳寿命也较长. 相似文献
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作为车身主要承载部件的B柱,由于其在使用过程中载荷情况的复杂性,焊点处疲劳破坏问题尤为严重。针对汽车传统B柱焊点布置不合理的问题,文中提出11种分区等距式焊点布置方案;利用有限元法求解出静力条件下各方案的结构应力,结合疲劳寿命预估理论进行软件间联合仿真分析,完成对各方案的焊点疲劳寿命计算,拟合出分区等距式布置方案中焊点间距与焊点寿命之间的关系曲线,最终确定一种最优方案,与原B柱焊点布置相比,既提高了焊点寿命,又减少了焊点个数,从而实现了焊点布置优化,达到了节省生产成本的目的。 相似文献
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在IC封装过程中,为了解决引线键合理论位置与实际位置不重合的问题,本文提出采用最小外接矩形拟合法求解芯片各个焊点和引线框架实际位置,实时校正在芯片引线键合工艺中由于贴片和装夹产生的位置误差。根据芯片引线键合批量化生产的特点分别建立软件的实验模块和批处理模块。在实验模块中,对芯片图像特征采用软件智能识别和人工辅助定义相配合的方法来实现芯片特征区域和类型的快速定义,形成与特定类型芯片相对应的特征信息文件和算法配置文件。在进行批量化生产时根据实验模块中建立的芯片特征和算法文件来进行焊点和引线框架的快速定位。这种方法在批处理运行时简化了算法的复杂度,提高了芯片焊点和引线框架的位置检测效率和引线键合质量。 相似文献
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研究了铝合金AA5754和AA6111-T4焊点的疲劳性能,获得了不同厚度及试件类型的焊点疲劳数据;研究了试件类型不同时焊点的疲劳失效模式,讨论了焊点疲劳裂纹的扩展形式;分析了铝合金焊点疲劳寿命的影响因素。结果表明:焊点疲劳失效模式主要有两种,分别是母材“眉状”裂纹断裂和焊点熔核界面断裂;母材对焊点疲劳寿命影响不大;循环载荷比对焊点寿命有一定的影响,增大载荷比导致焊点疲劳寿命略有下降;试件类型对焊点寿命有很大的影响,应在设计中避免焊点承受剥离载荷。 相似文献
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Qiang Guo Mei Zhao 《The International Journal of Advanced Manufacturing Technology》2005,26(7-8):887-895
The objective is to find whether fatigue of the solder joint or the location of the chip is related to the curvature and torsional
curvature when SMT solder joints are under vibration or shock condition. However, the torsional curvature is always omitted.
In this paper the relationship of curvature and torsional curvature is argued, and it is found that the quantity of the curvature
is closer to that of the torsional curvature and shows that omitting the torsional curvature is not accurate. Also, the fatigue
of the solder joint including torsional curvature is obtained. One kind of SMT printed circuit board (PCB) used in aviation
and spaceflight has been obtained to test its modes. According to the modal results, the location of the SMT assembly is not
very suitable and the reliability of SMT solder joints will decrease, which will make an unreasonable catastrophe appear.
Meanwhile, the location optimization including curvature and torsional curvature is considered and four areas are obtained
in the PCB to locate the chip for increasing the fatigue of solder joints. In this paper the results obtained by assuming
the PCB is simply supported in its four boundary. The other fixed condition will be calculated using a similar method. 相似文献
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Ouk Sub Lee Yeon Chang Park Dong Hyeok Kim 《Journal of Mechanical Science and Technology》2008,22(4):683-688
One of major reasons for the failure of solder joints is thermal fatigue. Also, the failure of solder joints under thermal
fatigue loading is influenced by varying boundary conditions such as the material of the solder joint, the materials of substrates(related
to the difference in CTE), the height of solder, the distance of the solder joint from the neutral point (DNP), the temperature
variation and the dwell time. In this paper, first, the experimental results obtained from thermal fatigue test are compared
to the outcomes from theoretical thermal fatigue life equations. Second, the effects of varying boundary conditions on the
failure probability of the solder joint are studied by using probabilistic methods such as the first order reliability method
(FORM) and Monte Carlo simulation (MCS). 相似文献
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R.S. Chen S.C. Tseng C.S. Wan 《The International Journal of Advanced Manufacturing Technology》2006,27(7-8):677-687
Among the PBGA (plastic ball grid array) packages, a 72-I/O OMPAC (overmolded effect array carrier) package is studied during
thermal cycling. The ANSYS software is applied to analyze the effects of some factors on the solder joint for the fatigue
life due to elastoplastic deformation of the electronic package; those factors are solder structure, shape, and pitch. The
result shows that the maximum equivalent plastic strain range occurs at two interfaces, one is between the solder joint and
the substrate, another one is between the solder joint and the printed circuit board. Moreover, the solder shape is determined
by the solder height and the pad diameter under a fixed value of solder volume. It is found that the convex-shaped solder
with larger height and smaller pitch has smaller maximum equivalent plastic strain range, which leads to the longer fatigue
life. In addition, there are two kinds of solder structure: pure solder joint and copper core solder joint. In the copper
core solder joint, the eutectic part becomes so small that a larger strain is induced. Therefore, the pure solder joint has
smaller maximum equivalent plastic strain range and longer fatigue life than the copper core solder joint. 相似文献
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电子电路中焊点的热疲劳裂纹扩展规律 总被引:4,自引:1,他引:3
采用试验方法研究表面贴装结构焊点在热疲劳过程中的疲劳裂纹扩展规律。试验研究中选用两种不同尺寸的焊盘及两种不同的钎料(包括传统的锡铅钎料和锡银铜无铅钎料SAC305),通过观测焊点截面上的裂纹萌生及扩展过程来研究焊点中的热疲劳裂纹扩展规律。研究结果表明,在热疲劳过程中,焊点经历热疲劳裂纹萌生和扩展的两个不同阶段,其中裂纹萌生所占的时间比例较小。在热疲劳后期,裂纹贯穿整个焊点从而造成焊点结构失效。研究发现,焊点结构失效过程中存在着两种不同的裂纹扩展模式,并且锡铅钎料焊点和SAC305无铅钎料焊点的裂纹扩展规律表现出明显的差异。另外研究还发现,当焊盘尺寸较小时,焊点的抗热疲劳性能相对较差;SAC305无铅钎料焊点的抗热疲劳性能优于传统锡铅钎料焊点。 相似文献
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板载芯片朝着小尺寸高密度方向发展,隐藏于芯片封装内部的微焊球缺陷检测愈发困难。针对工业高密度集成印刷电路板组件(PCBA)板载集成电路(IC)内部故障定位难、效率低的问题,提出一种芯片功能测试过程中采用红外热成像检测结合深度学习的多类型缺陷识别方法。以现场可编程门阵列(FPGA)单板双倍数据速率(DDR)存储芯片为对象,建立了芯片缺陷检测模型,搭建检测平台开展芯片内部焊点故障检测试验研究。设计程序实现芯片的数据存储与读出,同步采集红外图像序列,分析存储芯片读写过程中温度变化,并提取不同敏感测量区域热信号。构建卷积神经网络(CNN)分类模型,并进行超参数调优,实现了内部隐藏缺陷包括不同地址、数据、地址空间焊点故障的高效准确识别。引入迁移学习拓展应用于芯片其他9种不同焊点缺陷的检测,在10、20 dB高斯白噪声条件下分别达到95%、92%以上的准确率,从而为实际工业高密度集成PCBA板载微电子封装及可靠性分析提供了一种快速、有效的方法。 相似文献