精细间距BGA用PCB的设计与制作探讨

主要针对BGA电气连接设计做了简要阐述,并对高密BGA生产过程中存在的潜在可靠性影响做了分析。文章从一款0.4mm间距BGA的PCB板设计入手综合叠层规则、电气连接设计、信号回流、选材、表面处理等几个方面的考虑,在0.4mm间距BGA焊盘上采用盘中通孔和盲埋孔相结合的方式将其开发制作成功。     

盘中孔凸起失效探讨

随着电子产品可靠性需求的日益提升,产品封装密度的不断增加,类似盘中孔在焊后出现凸起已经不是一个可以忽略的工艺问题。文章从电流密度、镀层厚度、树脂凸起的高度、树脂的处理方式、盘中孔孔径、塞孔树脂的种类等几个方面探索盘中孔凸起失效的原因;通过DOE试验设计,结合相关的数据分析工具,快速、有效的确定了盘中孔凸起失效主要影响因子;结合实验结果,通过优化流程设计及工艺参数,并在实际生产中验证,完全改善了客户产品凸起失效现象。     

文献与摘要(117)

重要HDI板设计原则-导通孔Key HDI Design Principles—Vias文章是提供HDI板中导通孔设计的一些思路,导通孔的位置和孔的大小与多少对PCB面积、层数和线路密度有显著关系。文中主要叙述HDI板导通孔的位置选择、层间通道排列形式、BGA布局和BGA细节距布线、地/电源层互连孔等设计原则,运用有效的设计技术可以增加PCB功能和密度。(Happy T.Holden,CircuiTree,2011/03,共7页)     

酸蚀法制作无环金属化孔/槽产品的技术开发与应用

随着电子产品技术发展与高密设计的需求,PCB板设计的密度越来越小,板厚径比也越来越高。为了便于层面布线和满足密Pitch元器件的安装,设计无环PTH孔/槽的PCB板也日趋增多。对于无环PTH孔/槽PCB板的外层图形转移,目前业界通常是采用碱性蚀刻的工艺运作,创造性开发了几种无环PTH孔/槽PCB板外层走酸蚀的特殊制作方法,突破了树脂塞孔或高厚径比无环PTH孔/槽的PCB板无法走碱蚀的局限,在确保产品品质的同时也缩短了外层制作流程和生产周期。     

厚膜陶瓷基片通孔填充工艺

随着厚膜电路技术的发展,混合集成电路的集成度越来越高,要求提高混合集成电路陶瓷基片布线密度,而陶瓷基片双面布线是提高集成密度的较好方式之一.双面布线需要在厚膜陶瓷基片上制作通孔,并对通孔进行导体填充,以实现陶瓷基片正反两面电性能导通和散热等功能,而制作性能良好的导体孔柱是厚膜工艺的难点.重点介绍了通过优化填孔设备压力参...     

脉冲电镀在微盲孔填孔上的应用

电子产品的轻薄短小的发展趋势要求印制线路板的布线密度越来越高,这就使得板上的孔(包括通孔、埋孔和盲孔)径必须越来越小。在导通盲孔上直接叠孔的结构是实现最高布线密度的有效方法之一。作者通过水平脉冲电镀进行了微盲孔填孔电镀实验,在最佳的工艺条件下,在厚径比达到1.4:1的情况下仍然获得了良好的填孔效果,并对影响微盲孔填孔能力的一些因素进行了初步的探讨。     

0.5mm间距BGA芯片的PCB设计

目前,在高速PCB设计中,0.8mm间距BGA芯片的应用已非常普遍,但0.5mm间距BGA芯片的设计和焊接应用则相对较少。文章结合多层线路板的叠层规则、布线设计、信号回流以及钻孔工艺等技术,采用在0.5mm间距BGA芯片的焊盘上直接设计盘中通孔和一阶盲孔。在将PCB成本控制在规定预算范围内的同时,成功的将0.5mm间距BGA芯片应用在高密度互连PCB的研究与开发中。从生产出小批量单板的焊接情况看,系统上电后运行稳定,不存在短路和虚焊情况,从而较好的实现了电路工作性能,达到预先设计目标。     

薄型芯板CO2激光直接钻通孔工艺探讨

文章针对63μm薄型芯板通过日立CO₂激光钻机制作75μm激光通孔的工艺进行研究。分析了CO₂激光双面直接钻通孔工艺,正面钻孔余厚不足是导致反面钻孔漏钻孔的主要原因,并设计DOE实验探讨了光圈直径、脉冲宽度等对正反两面钻激光通孔孔型深度的控制及影响,得到了最优的通孔加工参数,实现了激光通孔制作和水平电镀填孔,并通过了相关可靠性测试。     

热风整平VIA HOLE塞孔探讨

为了达到客户要求，导通孔必须塞孔，经过大量的实践，我们改变传统的铝片塞孔工艺，用白网完成板面阻焊与塞孔。生产稳定，质量可靠。     

高厚径比值密集盘内孔树脂塞孔研究

设计DOE试验,对高厚径比值密集盘内孔(AR≥1 0,孔心距≤0.80mm)树脂塞孔进行了研究,通过分析确定了塞孔角度是影响树脂塞满度的主要因素,并找到了高厚径比值密集盘内孔树脂塞孔的最佳工艺参数。     

影响BGA封装焊接技术的因素研究

虽然表面贴装制造工艺已经纯熟,但是随着BGA封装的广泛应用以及焊球间距的逐步减小,给表面贴装制造工艺带来了新的挑战.基于BGA封装在表面贴装技术焊接中的应用,从印制电路板焊盘设计、印制电路板板材选取和保护、BGA封装选取和保护、印刷工艺、回焊炉温度曲线设定与控制等方面,阐述了影响BGA封装焊接技术的各个因素,进而提升B...     

弯曲应力状况下微型BGA封装可靠性比较研究

微型球栅阵列（μBGA）是芯片规模封装（CSP）的一种形式,已发展成为最先进的表面贴装器件之一。在最新的IxBGA类型中使用低共晶锡．铅焊料球,而不是电镀镍金凸点。采用传统的表面贴装技术进行焊接,研讨μBGA的PCB装配及可靠性。弯曲循环试验（1000～1000με）,用不同的热因数（Qη）回流,研究μBGA、PBGA和CBGA封装的焊点疲劳失效问题。确定液相线上时间,测定温度,μBGA封装的疲劳寿命首先增大,接着随加热因数的增加而下降。当Q。接近500S·℃时,出现寿命最大值。最佳Qη范围在300-750s·℃之间,此范围如果装配是在氮气氛中回流,μBGA封装的寿命大于4500个循环。采用扫描电子显微镜（SEM）,来检查μBGA和PBGA封装在所有加热N数状况下焊点的失效。每个断裂接近并平行于PCB焊盘,在μBGA封装中裂纹总是出现在焊接点与PCB焊盘连接的尖角点,接着在Ni3Sn4金属间化合物（IMC）层和焊料之间延伸。CBGA封装可靠性试验中,失效为剥离现象,发生于陶瓷基体和金属化焊盘之间的界面处。     

弯曲应力状况下微型BGA封装可靠性比较

文中采用传统的表面贴装技术进行焊接,研讨μBGA的PCB装配及可靠性。弯曲循环试验（1000με～-1000με）,用不同的热因数（Qη）回流,研究μBGA、PBGA和CBGA封装的焊点疲劳失效问题。确定液相线上时间,测定温度,μBGA封装的疲劳寿命首先增大,接着随加热因数的增加而下降。当Qη接近500s·℃时,出现寿命最大值。最佳Qη范围在300s·℃～750s·℃之间,此范围如果装配是在氮气氛中回流,μBGA封装的寿命大于4500个循环。采用扫描电子显微镜（SEM）,来检查μBGA和PBGA封装在所有加热因数状况下焊点的失效。每个断裂接近并平行于PCB焊盘,在μBGA封装中裂纹总是出现在焊接点与PCB焊盘连接的尖角点,接着在Ni3Sn4金属间化合物（IMC）层和焊料之间延伸。CBGA封装可靠性试验中,失效为剥离现象,发生于陶瓷基体和金属化焊盘之间的界面处。     

Board level solder joint reliability analysis of stacked die mixed flip-chip and wirebond BGA

Stacked die BGA has recently gained popularity in telecommunication applications. However, its board level solder joint reliability during the thermal cycling test is not as well-studied as common single die BGA. In this paper, solder joint fatigue of lead-free stacked die BGA with mixed flip-chip (FC) and wirebond (WB) interconnect is analyzed in detail. 3D fatigue model is established for stacked die BGA with considerations of detailed pad design, realistic shape of solder ball, and non-linear material properties. The fatigue model applied is based on a modified Darveaux’s approach with non-linear viscoplastic analysis of solder joints. Based on the FC–WB stack die configuration, the critical solder ball is observed located between the top and bottom dice corner, and failure interface is along the top solder/pad interface. The modeling predicted fatigue life is first correlated to the thermal cycling test results using modified correlation constants, curve-fitted from in-house lead-free TFBGA46 (thin-profile fine-pitch BGA) thermal cycling test data. Subsequently, design analyzes are performed to study the effects of 20 key design variations in package dimensions, material properties, and thermal cycling test conditions. In general, thinner PCB and mold compound, thicker substrate, larger top or bottom dice sizes, thicker top die, higher solder ball standoff, larger solder mask opening, smaller PCB pad size, smaller thermal cycling temperature range, longer ramp time, and shorter dwell time contribute to longer fatigue life. SnAgCu is a common lead-free solder, and it has much better board level reliability performance than eutectic solder based on modeling results, especially low stress packages.     

Board level solder joint reliability analysis and optimization of pyramidal stacked die BGA packages

Due to requirements of cost-saving and miniaturization, stacked die BGA has recently gained popularity in many applications. However, its board level solder joint reliability during the thermal cycling test is not as well-studied as common single die BGA. In this paper, solder joint fatigue of wirebond stacked die BGA is analyzed in detail. 3D fatigue model is established for stacked die BGA with considerations of detailed pad design, realistic shape of solder ball, and non-linear material properties. The fatigue model applied is based on a modified Darveaux's approach with non-linear viscoplastic analysis of solder joints. The critical solder ball is observed located between the top and bottom dice corner, and failure interface is along the top solder/pad interface. The modeling predicted fatigue life is first correlated to the thermal cycling test results using modified correlation constants, curve-fitted from in-house TFBGA (thin-profile fine-pitch BGA) thermal cycling test data. Subsequently, design analyses are performed to study the effects of 16 key design variations in package dimensions, material properties, and thermal cycling test conditions. In general, smaller top and bottom dice sizes, thicker top or bottom die, thinner PCB, thicker substrate, higher solder ball standoff, larger solder mask opening size, smaller maximum ball diameter, smaller PCB pad size, smaller thermal cycling temperature range, longer ramp time, and shorter dwell time contribute to longer fatigue life. The effect of number of layers of stacked-die is also investigated. Finally, design optimization is performed based on selected critical design variables.     

Comparative study of micro-BGA reliability under bending stress

The micro-ball grid array (/spl mu/BGA), a form of chip scale package (CSP), was developed as one of the most advanced surface mount devices, which may be assembled by ordinary surface mount technology. In the latest /spl mu/BGA type, eutectic tin-lead solder ball bumps are used instead of plated nickel and gold (Ni/Au) bumps. Assembly and reliability of the /spl mu/BGA's PCB, which is soldered by conventional surface mount technology, has been studied in this paper. The bending cycle test (1000 /spl mu//spl epsi/ to -1000 /spl mu//spl epsi/), is used to investigate the fatigue failure of solder joints of /spl mu/BGA, PBGA, and CBGA packages reflowed with different heating factors (Q/sub /spl eta//), defined as the integral of the measured temperature over the dwell time above liquidus (183/spl deg/C). The fatigue lifetime of the /spl mu/BGA assemblies firstly increases and then decreases with increasing heating factor. The greatest lifetime happens while Q/sub /spl eta// is near 500 second-degree. The optimal Q/sub n/ range is between 300 and 750 s/spl deg/C. In this range, the lifetime of the /spl mu/BGA assembly is greater than 4500 cycles if the assemblies are reflowed in nitrogen ambient. SEM micrographs reveal that both /spl mu/ & P-BGA assemblies fail in the solder joint at all heating factors. All fractures are near and parallel to the PCB pad. In the /spl mu/BGA assemblies cracks always initiate at the point of the acute angle where the solder joint joins the PCB pad, and then propagate in the section between the Ni/sub 3/Sn/sub 4/ intermetallic compound (IMC) layer and the bulk solder. In the CBGA assembly reliability test, the failures are in the form of delamination, at the interface between the ceramic base and metallization pad.     

基于FEA的Cu pad模型对焊点可靠性的影响分析

随着集成电路封装技术的发展,器件焊点可靠性成为国内外研究的重点,该文介绍了影响BGA焊点可靠性的常见因素,并以一块电路板为例,构建带有焊点亚结构——Cu pad和无Cu pad的两种电路板模型,仿真分析热循环条件下Cu pad对焊点可靠性的影响,为整板简化建模提供参考意见。     

点胶球形阵列封装组件机械弯曲可靠性研究

本文对比了两组经不同材料充胶的BGA组件和一组未充胶BGA组件在机械弯曲中的可靠性,包括三点弯试验和机械弯曲疲劳试验。结果发现在机械弯曲可靠性试验中,U1、U2材料的填充均能提高焊点的机械弯曲可靠性,并且U1的效果更好。通过对试样剖面显微观察,发现在用U1充胶的样品中,失效发生在焊点、PCB板处;而在其它两组样品中,失效发生在焊点、PCB板和铜焊盘三处。     

芯片级尺寸封装返修技术工艺评定

与传统表面安装器件（SMD）方形扁平封装（QFP）相比,芯片规模封装（CSP）及焊球阵列封装（BGA）在元件尺寸方面显著缩减。回流后在芯片下方形成焊点的位置表明,目检是不可能的。对有缺陷的芯片而言,返修的唯一方法就是除去并替换该芯片。虽然元件拆除易于完成,但替换过程也许更复杂。比较两种PCB焊盘清洗方法并从最后的焊盘抛光得出结论,在第一个工艺技术中,采用热氮气脱焊技术回流焊盘上的任何残余焊料,并通过液化真空除去。第二个技术工艺涉及到使用网状焊料芯吸法及有刀片尖的焊接烙铁来除去PCB焊盘上的残余焊料。评定的四个淀积技术工艺,包括最小型模板、浸渍传递、接触及非接触模压技术。最小型模板用于把焊膏淀积到返修的元件部位的电子制造业的传统方法。     

BGA元件组装及质量控制工艺

伴随高密度电子组装技术的发展,BGA元件成为高密度、高性能、多功能及高I/O数封装的最佳选择,并已经得到广泛应用。介绍了BGA元件的分类、焊盘设计、组装工艺、焊点检测技术及返修工艺。