Binary phase gratings for star couplers with high splitting ratio

Binary phase transmission gratings exhibiting a certain number N of central diffraction orders of equal intensity can be used to construct star couplers of the 1-to-N and N-to-N type. The calculation of the grating's groove structure is described, and first experimental results are presented.     

First-Principles Investigations of Precursor Molecules for Microclusters

Details of the reactive processes by which TiC and TiN microclusters are formed from precursor molecules in the gas phase are not clearly understood. We have performed ab initio calculations based on density functional theory methods in order to get some insight into the chemical reactions of precursor molecules. Using microcanonical molecular-dynamics we have simulated scattering processes between molecules consisting of the elements Ti, Cl, N and H. The simulations show that fluctuations of the kinetic energy can be large enough to break up bonds at moderate temperatures.     

先进芯片封装技术

微电子技术的飞速发展推动了新型芯片封装技术的研究和开发。本文主要介绍了几种新型芯片封装技术的特点,并对未来的发展趋势及方向进行了初步分析。     

环氧模塑料在半导体封装中的应用

环氧模塑料是一种重要的微电子封装材料,是决定最终封装性能的主要材料之一,具有低成本和高生产效率等优点,目前已经成为半导体封装不可或缺的重要材料。本文简单介绍了环氧模塑料在半导体封装中的重要作用和地位;分析了环氧模塑料性能对半导体封装的影响,并对不同半导体封装对环氧模塑料的不同要求进行了分析;最后展望半导体封装和环氧模塑料的未来发展趋势,以及汉高华威公司在新产品开发中的方向。     

论失效分析方法及流程

随着微电子业的飞速发展,失效分析广泛应用于宇航、工业、军品和民用产品中。失效分析是对失效器件进行分析检查,找出失效发生的原因,从而为改进、提高器件可靠性指明方向,在可靠性工程中具有重要的作用。     

Material property, compatibility, and reliability issues in diamond-enhanced, GaAs-based plastic packages

The mechanical performance and reliability of various Al₂O₃ ceramics were evaluated with intended applications as insulator frames for radio frequency/microwave power packages. Considering variations in base-flange material properties (CuW, CuMoCu), base-flange thickness (0.040 in., 0.020 in.), assembly process material (AgCu, Cu) assembly process temperature (860°C, 1080°C), and Al₂O₃ insulator material (96%, 99%, 20% ZrO₂/Al₂O₃, ZTA), finite element analysis (FEA) spatially resolved the fabrication-induced stresses during the assembly of CuW/Al₂O₃ and CuMoCu/Al₂O₃ structures and showed the critical regions to be the frame corners at the metal base-flange/Al₂O₃ interface. Bend strengths (four-point) and Weibull distributions were determined for each Al₂O₃ material and coupled with the FEA-predicted stresses for the various package configurations and assembly processes, the failure probabilities (P_f ) for the various CuW/Al₂O₃ and CuMoCu/Al₂O₃ structures were calculated. The CuMoCu-based structures exhibited the greatest warp deformation (concave upward, +), and highest stress and failure probability for all Al₂O₃ insulator varieties. The CuW-based structures exhibited an order-of-magnitude lower warp deformation (concave downward, −), an order-of-magnitude lower stress in the Al₂O₃, and in excess of seven orders-of-magnitude lower failure probability than CuMoCu-based structures, for all Al₂O₃ insulator varieties. Confirmational experiments were conducted using AgCu and direct-bond copper (DBC) assembly processes for selected varieties of CuW/Al₂O₃ and CuMoCu/Al₂O₃ structures. Al₂O₃ failure sites were identified using radiographic, ultrasonic and optical techniques and were in good agreement with model predictions of suspect structures and failure location. The strength and reliability data were considered in conjunction with relative cost for the Al₂O₃ ceramics to select an optimum frame insulator for the application.     

Chip Scale Package (CSP) solder joint reliability and modeling

A viscoplastic constitutive model was used to analyze the thermally induced plastic and creep deformation and low cycle fatigue behavior of the solder joints in Chip Scale Packages (CSP) mounted on Printed Circuit Boards (PCB). The time-dependent and time-independent viscoplastic strain rate and plastic hardening work factors of solder material were used in 2-D plane strain finite element models. The viscoplastic strain rate data was fitted to the viscoplastic flow equation. The plastic hardening factors were considered in the evolution equation. A viscoelastic constitutive model was used for molding compound. Finite element models, incorporating the viscoplastic flow and evolution equations for solder and the viscoelastic equations for molding compound, were verified by temperature cycling tests on assembled CSPs. The effect of the cyclic frequency, dwell time, and temperature ramp rate on the response of the viscoplastic deformation was studied for a tapeless Lead-on-Chip (LOC) CSP and a flexible substrate CSP. The ramp rate significantly affects the equivalent stress range in solder joints while a dwell time in excess of 10 min per half cycle does not result in increased strain range. The failure data from the experiments was fitted to the Weibull failure distribution and the Weibull parameters were extracted. After satisfactory correlation between the experiment and the model was observed, the effect of material properties and package design variables on the fatigue life of solder joints in CSPs was investigated and the primary factors affecting solder fatique life were subsequently presented. Furthermore, a simplified model was proposed to predict the solder fatigue life in CSPs.     

金属封装的形式及工艺技术

本文概述了金属封装的主要形式,并介绍了多种金属封装的结构。还重点介绍了金属封装的 关键工艺技术。     

微电子表面贴装关键技术与装备

提出了选择性拖焊工艺,浸焊工艺,在无需制作专门的模具即可完成。确认了采用屏蔽模具波峰焊接工艺,实现双面混装PCB波峰焊生产,大幅度提高双面混装PCB生产效率,减少粘贴阻焊胶的准备时间,降低生产成本,达到与传统波峰焊接兼容以及通孔回流焊接工艺,对提升焊接质量、减少工艺流程的优势。研究了SMT印刷设备的双路输送板发展方向、贴片设备的高速、高精密、多功能、智能化、多悬臂、多贴装头、柔性连接模块化发展方向、以及再流焊设备的多喷嘴气流控制、局部强制冷却、可监测元器件温度的发展方向。     

挠性基板制造工艺

应用于IC封装(Integrated Circuit,集成电路)的FPC(Flexible Printing Circuit,挠性印制板)称为挠性基板。随着电子产品向高密度、小型化、高可靠性方向发展,挠性基板线路制造工艺也从传统的减成法发展到半加成法,同时,一些新型的薄型挠性基板及埋嵌器件挠性基板也逐渐应用于航天、医疗及消费类电子等领域[1]。