SOI CMOS电路稳态寿命试验后漏电失效分析

针对SOI COMS电路稳态寿命试验后输入漏电流超标开展失效分析,分别对异常掉电致击穿、离子沾污、内部气氛不佳、芯片外表面污染、静电放电（ESD）等因素进行排查分析。定位电路失效原因为ESD防护用具状态不佳,导致试验过程中产生的ESD使电路输入端口二极管发生栅氧击穿。通过ESD测试设备模拟和原试验过程模拟2种方式,对失效模式进行复现验证。结果表明:SOI CMOS电路在试验过程中,即使试验员按要求佩戴防静电腕带和绝缘指套,若防静电腕带或绝缘指套状态不佳,仍易引发样品ESD失效;失效模式通常为电路输入端口微安级漏电,且该漏电在高温退火后会有部分恢复。建议在试验过程中选用全金属防静电腕带和防静电专用指套;若选用尼龙编制腕带,须定期更换。     

雷达罩抗静电涂层失效模拟

为分析雷达罩树脂型抗静电涂层失效的主要原因，采用有限元分析方法计算并对比了飞机起飞过程中雷达罩用树脂型涂层与橡胶型涂层受泥沙冲击后的位移变化。结果表明：剪切变形是造成树脂型涂层失效的主要原因。涂层的失效与冲击角度和泥沙的大小有关，在冲击角为90°时，涂层不会发生失效，在冲击角为30°、45°、60°时树脂型涂层均会发生失效，橡胶型涂层不会发生失效，但改用较大尺寸的SiO2粒子冲击，橡胶型涂层也会发生失效。模拟结果与涂层实际失效情况较符。     

聚焦离子束双束系统在微机电系统失效分析中的应用

MEMS惯性传感器是一种将运动物理量转换成电信号的传感器,其工作原理涉及物理学、机械学、微电子学科等。随着MEMS芯片尺寸的不断缩小和性能的不断提高,传统的半导体失效分析方法已很难满足MEMS器件失效分析的需求。本研究结合MEMS器件的工作原理和FIB双束系统的特点,通过聚焦FIB双束系统分析MEMS芯片中3种常见的失效形式,即产品存在漏电流、灵敏度异常和零输入偏差漂移等,分析得出MEMS芯片中常见的几种失效模式包括电极结构损坏、晶圆制造过程中引入的硅颗粒等典型失效模式,在此过程中展现出FIB双束系统在MEMS失效分析中特有的灵活性和优越性。     

聚丙烯挤出机螺钉断裂原因分析

某公司的聚丙烯25线挤出机出现挤出颗粒异常,原因为模板上固定螺钉发生多处断裂,为了探明螺钉出现断裂的过程,通过宏观检查、金相分析、化学成分分析、扫描电镜、能谱分析及硬度测试的分析方法,对发生断裂的螺钉进行了分析,探讨了断裂失效的原因。螺钉开裂为氢脆导致的延迟裂纹,由于电镀过程中氢原子渗入螺钉内部,同时电镀后未及时对螺钉热处理除氢,导致了螺钉的氢脆。     

压力机传动曲轴断裂失效分析

大连某公司的IY-21-400型直径300mm半闭式压力机的动力传动曲轴（以下简称曲轴），在使用过程中发生断裂，其使用年限仅为3年零4个月。该曲轴材料为45号钢，模锻、调质后，工作表面硬度应为230～255HB，终端区抗拉强度720～800MPa。对断裂曲轴的断口进行了宏观、微观形貌分析，对材料的化学成分进行了分析和性能的测试，最终确定了曲轴的断裂原因及其失效性质，进而对企业的生产工艺提出了改进措施。     

热循环条件下通孔插装焊点失效分析

通孔插装焊点是元器件与电路板接合最为常见的方式,以传统的通孔插装焊点为研究对象,按照IPC-9701标准设计热循环试验,在不同周期对焊点进行金相分析,对其失效行为及机理进行了研究,并测试了焊点的热疲劳寿命.同时采用有限元数值计算,应用基于蠕变应变的寿命模型,计算了焊点的热疲劳寿命.所得的试验结果与理论计算基本吻合.     

引信用导爆管的失效模式与分析

导爆管是爆炸序列中爆轰能量传递与放大的重要元件。通过对导爆管及其零部件的结构、功能和典型失效案例的介绍,总结出导爆管的功能失效模式主要包括瞎火、半爆、威力不足、意外起爆和结构损坏,零件及材料的失效模式主要包括管壳锈蚀、药剂受潮、药剂变质、药剂受污染、装药结构缺陷、装药量超差、装药密度超差等,并分析了各模式的失效原因;讨论了按产品功能和按零部件组成这2种导爆管的失效分析方法;为给出导爆管失效分析的一般分析方法,采用FMECA法对导爆管的功能、零件材料的各种可能失效进行了分析。     

耐火砖模具的双液淬火

我厂生产耐火砖用的模具（衬板），用GCr15钢制造。经粗加工→热处理→精加工等工序制成。使用过程中模具工作表面出现大小、深浅不一的凹坑及棱角崩裂现象，模具的使用寿命低。在对模具的失效原因进行了分析，并改进了热处理工艺后，模具的使用寿命提高了2倍。1原模具的失效原因原采用两种热处理工艺（图1），处理的模具失效形式各不相同（见表1）。用油淬处理时，由于模具厚度大，淬火、低湿回火后的硬度仅为40～45HRC，导致工作表面较早地发生凹坑磨损失效（图2），影响其寿命。凹坑的大小与耐火砖填料中硬质颗粒大小相一致。这可能是…     

温度对振动载荷下互连微焊点寿命的影响

设计了温度-定频振动两场耦合可靠性试验，应用两参数weibull统计分析和物理失效分析方法，分析了温度（25，100℃）对振动载荷下微焊点寿命的影响.结果表明，温度由25℃升高到100℃，振动载荷下的微焊点寿命显著提高，U₁位置处焊点寿命提高了106%，U₂位置处焊点寿命提高了180%；失效模式统计分析表明，随着温度的升高，焊点由界面裂纹（裂纹产生在界面处的金属间化合物与铜焊盘之间）转变为体钎料裂纹（裂纹产生在体钎料处），失效机制由脆性断裂转变为韧性断裂，失效机制的转变与焊点寿命密切相关.     

基于AFD的产品失效分析方法研究

失效分析是产品质量和可靠性保证中的重要技术.文章介绍了传统失效分析方法的类型和特征,引入了一种新的失效分析方法,即预期失效分析(AFD).在分析对比传统失效分析方法(FMEA)与AFD的基础上,提出了一种基于AFD的产品失效分析方法,给出了这种方法的工作流程.最后,用一个典型的例子对这种方法进行了说明.     

An experimental and analytical analysis on chip morphology,phase transformation,oxidation, and their relationships in finish hard milling

Milling hardened steels has emerged as a key technology in mold and dye manufacturing industry. The effects of cutting parameters on chip morphology, phase transformation and oxidation reaction of the chips during finish milling AISI H13 tool steel (50±1 HRc) with coated inserts were investigated in this paper. The chip morphology and phase transformation were examined using an optical microscope and a scanning electron microscope (SEM). The X-ray photoelectron spectroscopy was used to measure the chemical compositions of oxidation layer on chip surfaces. Shear-induced lamella structures characterized by jagged and rough appearance are the basic features of free surfaces. The microstructural analysis indicated that saw-tooth chips and white layers are produced only under certain combinations of cutting parameters of high cutting speed and feed rate. Based on chip color, chip morphology and X-ray photoelectron spectroscopy (XPS) analysis of the chip oxidation layer, the maximal instantaneous temperature at the tool–chip interface is semi-qualitatively estimated using the analytical method developed. In addition, chip color can be predicted based on the oxidation compositions.     

Characteristics of uncurled and reversely curled chip during orthogonal cutting

It has long been recognized that initially continuous chips are born curled. In this paper a new pattern of chip curl—reverse chip curl, named as chip down-curl, is observed during manufacturing of staggered integral high-finned tube using orthogonal planing with tools with flat rake face when rake angle is large enough and cutting thickness is small. With the increase of cutting thickness or decrease of rake angle, chips become uncurled and further increase of cutting thickness or decrease of rake angle leads to chip up-curl. The variations of chip curvature and conditions under which chips do not curl are obtained by experiments. The mechanisms of uncurled and reversely curled chip formation are investigated by analyzing microstructure of chip root. It is found that the uneven deformation that occurs on cross-section of chip results in reversely curled chip formation and no visible shear deformation that occurs on the primary shear zone of chip leads to uncurled chip formation.     

Continuous chip formation in drilling

The formation of coil continous chips in drilling often leads to chip disposal problems. This paper investigates the drill chip formation process of continuous chips (spiral chips and string chips). Chip removing motions and forces are analyzed. Two models are developed to predict the spiral and string chip formation, respectively. Based on the level of bending due to the chip generation at the cutting edge and deflection by the flute, these models qualitatively investigate relationship of the point angle and flute helix angle on the average chip length. Drilling experiments validate the chip length for spiral and string chip predicted by both models.     

Extension of basic geometric analysis of 3-D chip forms in metal cutting to chips with obstacle-induced deformation

In machining, chips are known to break mainly because of obstacle-induced deformation. Recently, the present authors had reported on a new and basic geometric analysis of 3-D chips in the absence of deformation after separation from the tool rake face. This paper continues the analysis to cover the full lifecycle of chips subjected to obstacle-induced deformation. The main contributions of this paper are the identification of the geometric properties that are likely to be preserved during obstacle-induced chip deformation and their implications, and the utilisation of these properties to obtain insights concerning the geometry of the tool–chip contact area. The new theoretical findings are verified against empirical data obtained through manual deformation of chips, video recordings of the development of obstructed chips, and the use of a specially prepared grooved tool that imposes a predetermined side-curl on the chip.     

Micro-end-milling of single-crystal silicon

Ductile-regime machining of silicon using micro-end-mill is almost impossible because of the brittle properties of silicon, crystal orientation effects, edge radius of the cutter and the hardness of tool materials. Micro-end-milling can potentially be used to create desired three dimensional (3D) free form surface features using the ductile machining technology for single-crystal silicon. There is still a lack of fundamental understanding of micro-end-milling of single-crystal silicon using diamond-coated tool, specifically basic understanding of material removal mechanism, cutting forces and machined surface integrity in micro-scale machining of silicon. In this paper, further research to understand the chip formation mechanism was conducted. An analysis was performed to discover how the chips are removed during the milling process. Brittle and ductile cutting regimes corresponding to machined surfaces and chips are discussed. Experiments have shown that single-crystal silicon can be ductile machined using micro-end-milling process. Forces generated when micro-end-milling single-crystal silicon are used to determine the performance of the milling process. Experimental results show that the dependence of the cutting force on the uncut chip thickness can be well described by a polynomial function order n. As cutting regime becomes more brittle, the cutting force has more complex function.     

304不锈钢车削的高压断屑技术研究北大核心

针对304不锈钢的车削过程中铁屑折断难,经常导致铁屑缠刀、加工表面划伤、排屑困难、影响自动化生产线的稳定运行等问题,设计开发7 MPa高压供液系统为车削过程提供高压冷却液。在高压冷却环境下,试验比较304不锈钢在粗、精加工的不同车削参数、刀片情况下的铁屑状态。研究结果表明,7 MPa高压冷却可以解决304不锈钢精加工铁屑不易折断的问题。铁屑的长度与冷却压力、切削参数、刀片有关,通过匹配适当的切削参数和刀片,铁屑长度可以被控制在较短的范围内。在此基础上,提出了一套针对304不锈钢车削加工的高压断屑方案,实现铁屑的可靠折断。     

7N01铝合金高速斜角切削过程中的切屑演化机理

目的 研究高强铝合金高速斜角切削参数对切屑形态及演化规律的影响,探究切屑形态转变的内在机理,为延长刀具使用寿命、改进加工工艺提供理论依据.方法 基于通用有限元软件建立7N01铝合金高速斜角切削三维数值模型,利用加工中心、三向测力仪进行切削试验,通过金相显微镜和扫描电子显微镜对切屑形貌进行表征,结合有限元仿真结果,探明切...     

Control of chip flow with guide grooves for continuous chip disposal and chip-pulling turning

This paper presents a new chip control method with guide grooves formed on the rake face to realize continuous chip disposal and chip-pulling turning. Chips are conventionally broken using chip breakers during turning operations for disposal. However, chips of highly ductile materials or thin chips generated in finishing can not be broken easily. In order to prevent the chips from jamming up, the authors propose to continuously guide the chips away from the cutting point. Special tool tips were developed and tested for guiding the chip. Chip controllability and mechanics of the chip-guided cutting are discussed in the present research.     

Study on swarf when sawing granite with diamond wire

The diamond wire-sawing process was developed to cut granite in both quarries and block processing plants. In this paper, swarf was collected from different areas along the sawing arc when sawing three granites. The particle size distribution and the morphology of the swarf were investigated systematically, along with the swarf formation mechanism in sawing. Granite swarf formation was dominated by transgranular fractures based on the morphology of sawn granite chips and the analysis of sawn chip size. A long cutting arc increased the movement among the swarf, tool, and workpiece, thereby inducing a secondary fracture in the sawn chip.      

The relation between chip morphology and tool wear in ultra-precision raster milling

In the field of ultra-precision machining, the study of the relation between chip morphology and tool wear is significant, since tool wear characteristics can be reflected by morphologies of cutting chips. In this research, the relation between chip morphology and tool flank wear is first investigated in UPRM. A cutting experiment was performed to explore chip morphologies under different widths of flank wear land. A geometric model was developed to identify the width of flank wear land based on chip morphology. Theoretical and experimental results reveal that the occurrence of tool flank wear can make the cutting chips truncated at both their cut-in and cut-out sides, and reduce the length of cutting chips in the feed direction. The width of truncation positions of the cutting chip can be measured and used to calculate the width of flank wear land with the help of the mathematical model. The present research is potentially used to detect tool wear and evaluate machined surface quality in intermittent cutting process.