芯片封装中铜丝键合技术的研究进展

铜线具有优良的机械、电、热性能,用其代替金线可以缩小焊接间距、提高芯片频率和可靠性.介绍了引线键合工艺的概念、基本形式和工艺参数;针对铜丝易氧化的特性指出,焊接时必须采用特殊的防氧化工艺,以改善其焊接性能;最后对铜丝键合可靠性及主要失效模式进行了分析.     

柔性传感器技术及其在智能包装中的应用

目的 随着5G技术的迅速发展,智能包装受到了广泛关注。文中通过总结柔性传感器技术及其近年在智能包装领域的应用,以期为未来智能包装技术的研发和应用提供参考依据。方法 通过文献分析柔性印刷电子技术、碳纳米技术以及硅光电子技术等柔性传感器技术的研究现状,总结柔性传感器在食品质量检测、显窃启包装设计和电商物流监测三方面的相关应用,为柔性传感器在智能包装中的进一步发展提供参考及建议。结论 大量研究表明,目前柔性传感器在智能包装中的应用仍处于起步阶段,各项技术仍在增长,不具备完全的商业可行性。柔型传感器拓宽了智能包装的功能及应用领域,可为内部产品提供良好的监测、记录和保障,值得加大研发投入,深入研究。     

利用银锡共晶键合技术的MEMS压力传感器气密封装

为了提高MEMS压力传感器的气密封装效果,利用银锡(Ag-Sn)焊片共晶键合的方法实现封装.首先介绍了工艺流程,然后利用X射线能谱(EDX)和剪切强度分析对共晶键合的温度和时间参数进行了优化,接着对9组静载荷下的剪切强度、Ag-Sn合金分布和键合层断面做了对比分析,最后做了X光检测、氦泄漏率对比测试及MEMS压力传感器实际效果测试.实验结果表明,在温度为230℃、加热时间为15 min、静载荷范围为0.003 9 MPa～0.007 8 MPa时,MEMS压电传感器的平均剪切强度达到14.22 MPa～18.28 MPa,X光检测无明显空洞,氦泄漏率不超过5×10-4Pa.cm3/s,测试曲线表明线性度较好.     

Thermal Noise Sensor Insulation Using Ultra-thin Ceramic Coatings

The insulation resistance and interference rejection of several prototype thermal noise sensors were measured. It was found that twisting the connecting wires as a pair optimizes the magnetic interference rejection. High-temperature-resistant wire insulation was developed by vapor depositing a few micrometer thick ceramic coating. The best insulation was obtained with a coating of 1.25μm SiO₂ + 1.5μm TiO₂ + 0.25μm ZrO₂. The insulation of four such coated pairs reached stable levels of 18 ± 3kΩ during a testing period of 1 week at 950°C under atmospheric conditions.     

应用双头电导探针技术测量气液两相泡状流局部参数

本研究应用双头电导探针技术测量气泡局部参数,从而揭示了气液两相泡状流的内部流动规律。     

一种流通过程现场测试跌落方位传感器的研究

跌落方位是跌落冲击中的一个重要参数,测量较为困难,提出了一种基于电容传感器的跌落方位现场测试新方案,分析了其基本结构、测量电路、测试原理和方法.     

MEMS封装技术

MEMS封装是在微电子封装技术基础上发展起来的一项关键的MEMS技术.首先提出了MEMS封装设计的一些基本要求,包括封装等级、封装成本、环境影响、接口问题、外壳设计以及热设计等方面.在此基础上,介绍了键合技术、倒装芯片技术、多芯片封装以及3D封装等几种重要的MEMS封装技术,并给出了一个封装实例.最后进一步探讨了MEMS封装的发展趋势及研究动向.     

MEMS压力传感器自动组装系统

研制了MEMS特种压力传感器的组装系统．首先给出了MEMS特种压力传感器组装工艺过程,并通过分析得出组装精度下降将导致传感器灵敏度和线性性能下降的结论．在此基础上确定了自动组装系统的组成结构,并详细介绍了研制的具有力感知功能的微操作手、三工位键合炉以及显微视觉等关键技术模块．通过分析现有硅膜焊盘图形对称性分布的特点,给出了一种芯片中心求取方法,为高精度自动组装奠定了基础．最后,将各模块集成建立了自动组装系统,给出了各个模块的控制节拍和流程,并通过实验证明该系统可实现5μm的组装精度和25s／个的组装效率,适用于多种MEMS传感器的自动组装作业．     

Polygonal Finite Element for Two-Dimensional Lid-Driven Cavity Flow

This paper investigates a polygonal finite element (PFE) to solve a two-dimensional (2D) incompressible steady fluid problem in a cavity square. It is a well-known standard benchmark (i.e., lid-driven cavity flow)-to evaluate the numerical methods in solving fluid problems controlled by the Navier–Stokes (N–S) equation system. The approximation solutions provided in this research are based on our developed equal-order mixed PFE, called Pe₁Pe₁. It is an exciting development based on constructing the mixed scheme method of two equal-order discretisation spaces for both fluid pressure and velocity fields of flows and our proposed stabilisation technique. In this research, to handle the nonlinear problem of N-S, the Picard iteration scheme is applied. Our proposed method’s performance and convergence are validated by several simulations coded by commercial software, i.e., MATLAB. For this research, the benchmark is executed with various Reynolds numbers up to the maximum . All results then numerously compared to available sources in the literature.     

Acoustic Wave Flow Sensor Using Quartz Thickness Shear Mode Resonator

A quartz thickness shear mode (TSM) bulk acoustic wave resonator was used for in situ and real-time detection of liquid flow rate in this study. A special flow chamber made of 2 parallel acrylic plates was designed for flow measurement. The flow chamber has a rectangular flow channel, 2 flow reservoirs for stabilizing the fluid flow, a sensor mounting port for resonator holding, one inlet port, and one outlet port for pipe connection. A 5-MHz TSM quartz resonator was edge-bonded to the sensor mounting port with one side exposed to the flowing liquid and other side exposed to air. The electrical impedance spectra of the quartz resonator at different volumetric flow rate conditions were measured by an impedance analyzer for the extraction of the resonant frequency through a data-fitting method. The fundamental, 3rd, 5th, 7th, and 9th resonant frequency shifts were found to be around 920, 3572, 5947, 8228, and 10 300 Hz for flow rate variation from 0 to 3000 mL/min, which had a corresponding Reynolds number change from 0 to 822. The resonant frequency shifts of different modes are found to be quadratic with flow rate, which is attributed to the nonlinear effect of quartz resonator due to the effective normal pressure imposing on the resonator sensor by the flowing fluid. The results indicate that quartz TSM resonators can be used for flow sensors with characteristics of simplicity, fast response, and good repeatability.     

Measurements of the Thermal Conductivity of Molten Lead Using a New Transient Hot-Wire Sensor

The paper reports new measurements of the thermal conductivity of molten lead at temperatures from 600 to 750 K. The measurements have been carried out with an updated version of a modified transient hot-wire (THW) method, where the hot-wire sensor is embedded within an insulating substrate with a planar geometry. However, unlike previous sensors of the same type, the updated sensor works with the hot-wire divided into three thermally isolated parts. The operation of this sensor has been modeled theoretically using a finite-element (FE) analysis and has subsequently been confirmed by direct observation. The new sensor is demonstrated to have a higher sensitivity and a better signal-to-noise ratio than earlier sensors. Molten lead is used as the test fluid. It has the lowest thermal conductivity of any material we have yet studied. This allows us to probe the limits of our sensor system for the thermal conductivity of high-temperature melts. It is estimated that the uncertainty of the measurements is 3% over the temperature range studied. The results are used to examine the application of the Wiedemann–Franz (W-F) relationship.     

漆酚甲醛缩聚物无铬化学镀铜

通过改变施镀工艺的pH值、温度、时间以及镀液配方中主盐浓度、还原剂浓度,得到不同条件下的化学镀层厚度、外观和镀速等试验结果,对漆酚甲醛缩聚物(PUF)基材上的化学镀铜工艺进行了研究;并用扫描电镜(SEM)、动态机械热性能(DMTA)、差示扫描量热分析(DSC)和热重分析(TG)等方法研究了镀层的形态与性能.本工艺可在PUF表面镀上一层均匀、色泽光亮的金属铜膜,其粒径匀称、排布规整、镀层致密;金属化聚合物的耐热性显著提高.     

透平转子的包装工艺

对现行透平转子包装存在的问题进行分析,指出一般常用包装方法存在的缺点以及造成的经济损失,提出改进透平转子包装的方案和具体包装工艺。     

铜基封装材料的研究进展

具有高导热性的铜基封装材料可以满足大功率器件即时快速大量散热的要求,是一种重要的封装材料.综述了Cu/Mo、Cu/W传统铜基封装材料和Cu/C纤维、Cu/Invar(Mo、Kovar)/Cu层状材料、Cu/ZrW2O8(Ti-Ni)负热膨胀材料及Cu/SiC、Cu/Si轻质材料等新型铜基封装材料的性能特点、制备工艺与问题.指出轻质Cu/Si复合材料将是铜基封装材料中一个新的具有前景的研究方向.     

自动定量称量包装传感器信号去噪算法

目的为了有效滤除自动称量控制系统中的噪声信号,提升称量系统的稳定性和精确度,提出一种基于BP神经网络粒子滤波的称量信号去噪方法。方法在粒子滤波算法中映入了BP神经网络,利用BP神经网络的非线性映射特点,对权值进行分裂和选择,将观测值看作神经网络的目标信号,通过神经网络中的多次训练增大小权值粒子的权重,从而提高粒子滤波算法的多样性。结果仿真和实验结果表明,BP神经网络粒子滤波方法能有效滤除称量包装系统中的噪声信号,提升传感器信号品质。结论该滤波方法大大提升了称量系统的稳定性,有效提高了称量包装的精度,所述控制方法可以明显提高定量称量控制过程的稳定性、精确性以及鲁棒性。     

微机电系统热式流量传感器计量原理的数值研究

采用计算流体力学仿真手段,根据MEMS热式流量传感器的计量原理进行机理建模,对不同流速下微机电系统传感器表面的温度场分布进行数值模拟与分析,考察了传感器温差输出信号与标准流速之间的关系,所得结论与理论相符。同时,通过与实验数据比较,验证了仿真模型的正确性。此外,通过分析热式流量传感器在不同温度和压力下的热场特性,发现其存在一定的温度和压力效应。当工作温度、压力波动较大或严重偏离标定状态时将带来较大的测量误差。     

Unexpected Thermal Fracture of a Ceramic Sensor

A ceramic substrate bonded to an electronic sensor was reported to crack during thermal testing between −46 and +71 °C. Initially, this was assumed to occur at high temperature because of the thermal expansion of a polymer pad under the sensor. However, further investigations indicated that fracture was also occurring at low temperature. This was surprising since the suspected cause of fracture was pressure exerted by the polymer pad under the ceramic. This polymer pad has a coefficient of thermal expansion much greater than any other component. Conventional wisdom suggests that this failure would happen only during expansion of the pad during high temperature phases of temperature cycling. Subsequent dynamic thermal analysis revealed that differential contraction of the steel clamp fasteners was causing pressure to be exerted on the ceramic during the initial phase of the cold cycle. In addition, lateral constraint of the polymer pad caused pressure to rise to counterintuitive levels. An alteration of the geometry of the pad proved to be the simplest and most economical solution. This was confirmed by subsequent testing.     

热式微小流量传感器温度场及信号提取分析

热式流量传感器由于其结构简单、没有机械运动部件等固有的优点,在微小流量测量领域具有明显优势.针对微小气体流量测量领域毛细取样管路及其内部气体流体,进行热力学、流体力学理论分析,配合信号处理电路的分析,提出了消除环境温度影响的电路方法,同时使用MATLAB语言,用数值计算方法,获得了气体流量与毛细取样管路温度场之间的关系...     

铜箔表面电镀铜粗化工艺

国产铜箔表面粗糙度不够,直接影响镀镍层的形态,用作高分子温度系数热敏电阻时与高分子聚合物的结合强度不够,致使其使用性能不迭标.为了提高铜箔与有机材料问的结合强度,常采用表面粗化工艺.采用酸性硫酸盐镀铜工艺对铜箔表面进行粗化,并用微分电容曲线的电化学测量和扫描电镜及金相显微镜表征了铜箔粗糙度.结果表明,粗化电流密度为20 A/dm2时,粗化效果最为明显,在抗拉端面面积相同的情况下,国产铜箔抗拉强度由粗化前的60.85 N/cm2增大到粗化后的137.81 N/cm2,接近国外商品铜箔的抗拉强度138.26 N/cm2.