芯片凸点的几种工艺制造方法

本介绍了目前通常的几种芯片凸点制造方法，其中对焊料合金球凸点，物理化学淀积金属凸点，金丝球焊形成金凸点等作了一些工艺分析和适用分析。     

微电子器件引线一次焊接技术——面键合技术

本文比较完整地介绍面键合技术。其中包括铜球焊法、可控塌扁面键合法、多层金属凸点面键合法、单金属硬凸点面键合法(单金属金凸点)、单金属铝焊柱衬底等技术,并介绍多层金属金硬凸点的制造工艺。     

喷镀系统在凸点制备中的应用

介绍了利用电镀法制造晶圆凸点的典型工艺和喷镀设备.喷镀系统是凸点电镀设备中最关健的部件.通过计算机软件模拟试验,对喷镀系统中的喷杯体和匀流板等各种参数和位置进行了优化设计,并在设备上应用验证.该系统在凸点电镀设备上应用后,在晶圆片上成功做出了高质量的均匀凸点,取得了良好效果.     

电镀技术在凸点制备工艺中的应用

简要回顾了微电子封装的发展历程;描述了FC、BGA、CSP以及WLP的基本概念;归纳了凸点类型以及各种凸点的不同用途;着重介绍了电镀金、金锡、锡铅、锡银和化学镀镍凸点的工艺过程,最后简单介绍了制备凸点的电镀设备。     

凸点—焊料法倒扣焊工艺技术研究

为满足电子系统高可靠、小体积、轻重量的要求,微电子封装技术向高密度的方向发展,随着封装尺寸的小型化和微型化,出现了许多新的封装形式和封装技术,其中最具代表性的就是倒扣焊技术。为此,我们开发了凸点－焊料倒扣焊工艺。本文详细叙述了芯片上Au凸点的制造技术,基板上Pb-Sn焊料凸点的制造技术和凸点－焊料倒扣焊的下填充技术,并对倒扣焊样品进行了可靠性考核,同时与国外的相关技术进行了比较,结果说明,凸点－焊料法倒扣焊技术完全可以满足高可靠军用电路的要求。     

Pb/Sn凸点的制备

介绍了用电镀法制备Pb / Sn凸点的工艺,包括:凸点的设计,圆片的准备,溅射UBM(凸点下金属层),厚膜光刻,电镀Cu柱, Pb / Sn凸点,回流凸点等。结果表明:采用电镀法可以得到球形Pb / Sn凸点,50μm的厚胶工艺是可行的。     

基于MCM-Si及倒扣焊技术的产品可靠性研究

本文介绍了硅基薄膜基板、SnPb焊料凸点和凸点倒扣焊（FCB）等实用化工艺技术,探讨了MCM—Si高可靠性产品的关键工艺。重点对芯片凸点的UBM可靠性、凸点与硅基的倒扣焊接可靠性、芯片凸点拉脱力等对产品可靠性有重要影响的关键点进行了研究。     

焊料凸点回流时的桥接现象研究

在用回流焊料凸点时,常会发生凸点的桥接现象,致使芯片报废。此时,相邻的多个凸点彼此融合,聚集成一个更大的焊料球,并吸干先前各凸点中的焊料。本文研究了电镀PbSn凸点和蒸发铟凸点的回流过程中出现的桥接现象。介绍了桥接现象产生的过程及其背景,分析了桥接现象的机理,提出了改进措施。     

用于倒装芯片的金球凸点制作技术

倒装芯片中凸点用于实现芯片和基板的电路互连,芯片凸点的制作是倒装芯片技术的关键技术之一.对金球凸点制作进行了介绍.金球凸点直接粘附于芯片上,同时又可具有电路互连的作用,可以完成倒装芯片与基板的电气连接.金球凸点的优势是简单、灵活、便捷、低成本,最大特点是无需凸点下金属层(UBM),可对任意大小的单个芯片进行凸点制作,平整度可达到±4μm.     

MEMS压力传感器上柔性化凸点制备方法

介绍了一种适用于MEMS压力传感器的低成本、柔性化凸点下金属层(Under Bump Metal,UBM)和凸点(Bump)的制备工艺。其中凸点下金属层分为Ni-P/Cu两层,使用化学镀的方法沉积在Al焊盘表面;凸点通过焊膏印刷回流预制于陶瓷基片上,再通过转移工艺移植到焊盘上。为了检验此套工艺制出的凸点结构是否具有足够的强度,对凸点进行了剪切破坏试验。结果表明,凸点与凸点下金属层、凸点下金属层与Al焊盘均结合牢固,破坏主要发生在焊料凸点内最薄弱的金属间化合物层(Intermetallic Compound,IMC)。     

Manufacturing of Cu/electroless nickel/Sn-Pb flip chip solder bumps

A process for manufacturing Cu/electroless Ni/Sn-Pb solder bump is discussed in this paper. An attempt to replace zincation with a Cu film as an active layer for the electroless Ni (EN) deposition on Al electrode on Si wafer is presented. Cu/electroless Ni is applied as under bump metallurgy (UBM) for solder bump. The Cu film required repeated etches with nitric acid along with activation to achieve a satisfactory EN deposit. Fluxes incorporating rosin and succinic acid were investigated for wetting kinetics and reflow effectiveness of the electroplated solder bump. The solder plating current density and the reflow condition for achieving solder bumps with uniform bump height were described. The Cu/EN/Sn-Pb solder system was found to be successfully produced on Al terminal in this study that avoids using zincating process     

Layer Structure and Thickness Effects on Electroplated AuSn Solder Bump Composition

The eutectic gold–tin (AuSn) solder composition is receiving increased attention for packaging applications. In addition to the environmental benefits of removing lead compounds from electronic manufacturing, gold–tin eutectic also exhibits desirable mechanical properties such as high strength and low thermal fatigue. However, some methods of deposition for this solder require complicated processes or limit the minimum bump size. This paper explores the formation of AuSn eutectic solder bumps using sequential electrodeposition of Au and Sn to determine the effect of layer thickness and sequence on the composition and structure of the resulting solder bump.     

Process-dependent contact characteristics of NCA assemblies

The physical contact characteristics of a nonconductive adhesive (NCA) type of flip-chip-on-glass (FCOG) assemblies during manufacturing process and temperature variation is explored by using three-dimensional (3D), nonlinear finite element analysis together with the so-called "death-birth" simulation technique. The contact mechanics of two typical types of micro-bump bonding technologies, i.e., the metal (i.e. Au alloy) and composite bumps, are extensively addressed, and substantially compared. The validity of the modeled contact characteristics is further verified by an electrical contact resistance measurement that adopts a four-point probe method and an equivalent circuit approach. Finally, through the parametric study, the dependence of the contact stress at the bumps and the peeling stress at the UV resin on a number of geometry and material design parameters is effectively identified. Both the modeling and experimental results show that the bump height uniformity is a key factor in the overall contact performance of the assembly, and should not be neglected from the analysis. In addition, it is identified that the composite-bump bonding technology outperforms the metal-bump assembly as a whole in terms of the contact consistency and stability due to its better bump uniformity and compliance. Furthermore, it is surprising to find that there is a full disagreement in the parametric results of the bump height and Al thickness between the shorter bump and the taller among those nonuniform bumps, and more importantly, an increase of the bump height or a reduction of the Al overcoat thickness would enhance the overall contact performance of the assembly.     

Driver IC and COG Package Design

This paper investigates the interconnection between the driver integrated circuit (IC) and glass substrate via anisotropic conductive adhesive (ACF) of chip on glass package. The conductive particle deformation is evaluated using a novel method, optical microscope (OM) inspection. The proposed method is more convenient than the traditional approach using scanning electron microscopy applied in the manufacturing process. Interconnection performance is easily judged using OM, allowing poor interconnection between the driver IC and glass substrate to be screened out. Several types of driver ICs with different bump area ratios (total input bump area/total output bump area, input/output ratio) and length/width (L/W) ratios are designed in this experiment. The conductive particle deformations are investigated in this study. Driver ICs with L/W ratios larger than 15 have better conductive particle deformation uniformity at each position. The average deformation degree at the driver IC center position is larger than that at the side and edge positions. The deformation degree at the input position with a smaller bump area is better than that at the output position. The conductive resistance increases with the reliability testing time because of the thermal stress effect and softening of the ACF polymer material. The deformation degree is related to the conductive resistance of the interconnection. The conductive resistance is lower at the center and input positions with larger deformation degree.     

Automated Solder Inspection Technique for BGA-Mounted Substrates by Means of Oblique Computed Tomography

High-density large-scale integration (LSI) packages such as ball grid arrays (BGAs) are being utilized in car electronics and communication infrastructure products. These products require a high speed and reliable inspection technique for their solder joints. Oblique computed tomography (OCT) was proposed as a novel imaging technique for BGA-mounted substrates, and it is being introduced in many manufacturing factories. Although operators examine OCT images manually, the establishment of an automated inspection technique is required from the viewpoint of an operator's load and the fluctuation of the inspection results. In this paper, a novel automated solder inspection technique by means of OCT is proposed. This technique consists of position adjustment, bump extraction, character extraction and judgement. Moreover, by combining five characteristic features, the condition of a solder bump was determined in computer algorithm. In this paper, linear discriminate analysis and an artificial neural network technique are introduced as the determination methods. In the experiments, these techniques are evaluated by using actual BGA-mounted substrates. The correct rate of inspection reached 99.7% in both the determination methods, which clearly indicates that proposed method may be useful in practice.     

Reflow and property of Al/Cu/electroless nickel/Sn-Pb solder bumps

Materials interaction, shearing strength, and bump growth of Al/Cu/electroless nickel/Sn-Pb solder bumps were investigated with respect to reflow conditions. Shearing strength of the solder bump is as high as 64 g/bump for a bump pad dimension of 100×100 μm. Reflow temperature enhances the shearing strength while repeating reflow downgrades the shearing strength to a lowest value of 35 g/bump. A greater bump height is achieved when reflow was conducted at a slower heating rate. Cu penetrates the electroless nickel (EN) layer after reflow, while Al remains unmoved. The diffusion behavior of Cu through the EN layer is discussed. Ni-Sn and Cu-Sn intermetallic compounds form during reflow     

凸点晶圆测试共性问题研究与应用

集成电路"轻、薄、小"的趋势使新封装技术在产业中不断得以应用。晶圆凸点工艺作为新封装技术的关键工序尤为重要,相应的凸点晶圆测试方案是产业面临的现实问题。针对凸点晶圆测试中出现的新问题和技术难点,结合在多个凸点晶圆测试开发和量产过程中积累的成功经验,按照晶圆测试控制流程,依次阐述在凸点晶圆测试中碰到的共性问题,如针对凸点晶圆测试的新型探针卡及测试过程中针压控制、凸点损伤与量产测试中关键操作控制、在线清针与检查、工艺数据测试衔接等。并提供预防凸点损伤的过冲控制参数自动获取解决方案和凸点晶圆并行测试解决方案,实现凸点晶圆可靠的量产测试,有效提高了凸点晶圆的测试能力。     

浅析贴片设备

由于表面组装技术不断地朝着小型化的方向发展 ,特别是在细间距、小直径的凸点和使用的焊剂等诸多因素的推动下 ,促使设备供应商根据倒装芯片技术的需求而研制新一代的贴装机。介绍了设备的制造厂家根据倒装芯片的特点 ,采用柔性 (软件 )方法和视觉系统等方案对现有的设备进行改型 ,从而实现了贴装设备的自动化。实践证明研制开发倒装芯片技术的自动组装技术可使生产率、材料和工艺设备取得明显的进步     

用于倒装芯片的晶片凸点制作工艺研究

倒装芯片在电子封装互连中占有越来越多的份额,是一种必然的发展趋势,所以对倒装芯片技术的研究变得非常重要。倒装芯片凸点的形成是其工艺过程的关键。现有的凸点制作方法主要有蒸镀焊料凸点、电镀凸点、微球装配方法、焊料转送、在没有UBM的铅焊盘上做金球凸点、使用金做晶片上的凸点、使用镍一金做晶片的凸点等。每种方法都各有其优缺点,适用于不同的工艺要求。介绍了芯片倒装焊基本的焊球类型、制作方法及各自的特点,总结了凸点制作应注意的问题。