BGA器件焊接合格率的预测模型

在表面贴装技术(SMT)大规模生产过程中,如果能够对焊接合格率进行预测,无疑对提高SMT产品的生产率、产品可靠性及成本控制具有重要意义.以球栅阵列(BGA)器件为例,研究SMT焊接合格率的预测方法.通过统计分析,结合焊点成形软件的方法,建立了BGA器件焊接合格率的预测模型,运用该模型可以找出影响焊接合格率的制约因素.结合仿真技术模拟焊点形态,发现引起焊接缺陷各参数之间的关系,并提出相应的解决方案.     

手工焊接印制板装配工艺及检测方法的应用

为了提高手工焊接印制板质量水平,主要针对影响手工焊接印制板质量主要因素—焊点的检查,改进了手工印制板装备制造工艺和检测方法。经过质量检测证明:采用改进后的印制板检查方法使得手工印制板合格率提高到98%以上。     

HKPCA&IPC展会首届(OK国际杯)手工焊接竞赛

手工焊接可以称之为一门艺术,在电子产品制造中担当着重要的作用。电子产品焊点的质量与可靠性很大程度上决定了产品的质量和可靠性,而与其他焊接工艺相比,手工焊接的焊点质量更加依赖于从业者的操作技艺与水平。多少年来,我国的手工焊接技能主要依靠师徒传承的方式进行,没有完整而规范的     

先进的表面组装制造方法

本主要论述了再流焊接技术在通孔元件中的应用，这种技术对传统的通孔元件的波峰焊接技术是一个重大的技术创新。其有诸多优点，不仅实现了柔性设计，而且还具有波峰焊接工艺不能实现的用途。中将波峰焊接和再流焊接技术进行了比较，这种创新技术减少了工艺步骤及相关的材料，为此，节约了制造成本，同时仍保持原有的性能，并重点指出只有对传统的制造方法进行重大改革才能获得有竞争优势的技术突破。为实现制造工艺的现代化，而对表面组装制造进行连续的测评，以便在不改变工艺性能的同时，获得行之有效的制造方法。在很多情况下，采用先进的表面组装制造方法可以减少若干工艺步骤：有两种较受欢迎的工艺：单中心再流焊接(SCRS)或是侵入式再流焊接和双面再流焊接。这些工艺虽然不是新工艺，不过，许多公司多年来一直都在使用这些工艺，而且其中一些公司还将这些工艺用于其部分混合技术组装生产中。这些工艺的其中一些突出特点是对通孔元件的再流焊接进行了透彻地研究，这项研究是1986年由美国的一家重点电子制造厂家实施的。通过一系列的实验来验证和确定所有的关键操作参数。花费了十年的时间，通过使用这种工艺对无以数计的焊点进行了研究，资料记载表明没有出现过任何现场故障，焊点缺陷率保持在4--7ppm。     

无铅焊点的可靠性问题

焊点的质量与可靠性很大程度决定了电子产品的质量。随着环境保护意识的增强，无铅焊料、无铅焊点成为了近年来的研究热点问题。无铅焊点由于焊料的差异和焊接工艺参数的调整，必不可少的会给焊点可靠性带来新的影响。本文从设计、材料、及工艺角度分析了影响无铅焊点可靠性的因素，对无铅焊点可靠性测试方法做了介绍。     

手工焊接中焊点工艺及质量控制

在电子产品的制作中,使用电烙铁手工焊接元器件一直是不可缺少的操作内容,因此需要对手工焊接技术要领多加练习,才能保证电子产品的可靠质量。文中介绍了手工焊接中焊点形成的机理,阐述了印制板手工焊接的操作步骤。结合工程实践,分析了使用电烙铁手工焊接中因操作手法和工艺方法不当容易导致的焊点缺陷,并提出了引起缺陷的原因以及解决问题的措施,从而保障电子产品的可靠质量,减少产品返修率,提高了焊接及生产效率。     

再流区工艺参数对焊接可靠性的影响

影响表面组装焊接可靠性的因素很多，从钎焊机理入手，经过金相分析就再流区工艺参数对焊点微观结构的影响进行了研究，并结合焊点拉脱试验提出了再流区工艺控制的原则。     

响应面法分析SAC305焊球激光焊接参数对润湿角的影响

基于响应面法分析了激光植球焊接工艺参数对SAC305焊料润湿性的影响。设计单因素试验并进行植球焊接，分析激光功率、加热时间和氮气压强对焊点润湿角的影响规律。进一步设计响应面法试验，建立回归方程预测模型，并对焊接工艺参数进行优化。结果表明：随着激光功率、加热时间和氮气压强增大，焊点润湿角逐渐减小，三者对焊点润湿角影响大小排序为：激光功率>加热时间>氮气压强；直径600μm焊球的响应面法优化工艺参数为激光功率84.27%,加热时间0.064 s,氮气压强1 089.48 Pa,焊点润湿角为31.032°,焊点润湿铺展良好。经实验验证，响应面法预测值与实测值相近，可为优化激光植球焊接工艺参数提供参考。     

热压焊接工艺优化研究

热压焊接是连接柔性电路板和刚性电路板的一种焊接工艺,作为微电子表面组装技术领域的新兴制造工艺和重要组成部分,稳定和高效的热压焊接工艺无疑是保证产品良好品质的重要环节。通过统计分析热压焊接的主要失效模式,并从材料、工艺参数及设备进行实验比对和实验设计(DOE)找出各主要失效模式的影响因素及其之间的相互关系,确定最佳工艺参数。     

汽车车架焊接工艺和工装设计分析

随着我国国民生活水平的迅速提升,汽车的数量也在与日俱增,为了全面了解汽车架构工艺,提高汽车使用的安全性能,本文结合某公司一款轻型载货汽车为例对汽车车架焊接工艺及工装设计进行了探析。之所以对汽车车架焊接工艺及工装设计展开论述,是因为汽车车架焊接工艺及工装设计是汽车制造加工过程中的重要环节,对汽车整体制造加工质量起着决定性作用。     

低银无铅焊膏板级封装工艺和焊点可靠性试验

针对低Ag无铅焊膏的市场需求,研究开发了一种适用于99.0Sn0.3Ag0.7Cu低Ag无铅焊膏用松香型无卤素助焊剂(WTO—LF3000),配制了相应的无铅焊膏(WTO—LF3000—SAC0307),并对其板级封装工艺适应性及焊点可靠性进行了考察,用测试后样品的电气可靠性作为接头可靠性评价条件。结果表明:所开发的低Ag无铅焊膏熔点和润湿性符合产品实际要求。配制的焊膏印刷质量良好,焊点切片观察其孔隙率<25%,满足行业标准IPC—A—610D之要求。样品分别经跌落、震动和温度循环试验后,无焊点脱落等现象,电气功能正常。     

Mode I fracture toughness testing of eutectic Sn-Pb solder joints

The mode I plane strain fracture toughness of Cu/63Sn-37Pb solder joints was measured using a technique based upon the ASTM standard methods for fracture toughness testing. A solder joint compact tension sample geometry was selected for the evaluation and each sample was manufactured using a capillary soldering system that provides excellent control over critical processing parameters. The mode I plane strain fracture toughness based on these tests is 8.36 MPa√m. Failure is dominated by microvoid nucleation in the solder and fracture of the intermetallic particles that are located at the solder/copper interface. The validity of the testing method used and the relevance of the results to solder joint reliability are discussed.     

Solder balling of lead-free solder pastes

Solder balling in Sn/Ag/Cu solder pastes was studied in this work. Three different solder pastes, several different reflow profiles and conditions, and two stencil thicknesses were used in the investigation. During the first phase, called the verification phase, the solder pastes were checked to ensure they met the minimum requirements. In the process-screening phase, the reflow profile was varied. Results show that besides flux chemistry, reflow atmosphere plays the major role in solder balling. The average number of solder balls with the best paste was one fifth of that with the worst paste. Furthermore, with all the pastes, the number of solder balls dropped close to zero when nitrogen atmosphere was used. Another finding during the reflow process screening was the influence of the stencil thickness on the solder-balling result. With a thinner stencil, two of the pastes exhibited significant solder balling. This is assumed to be caused by the different ability of fluxes to withstand oxidation during the preheating in the reflow process. In the last phase, the effect of the solder-paste particle size on solder balling was studied more closely. The flux chemistry was kept unchanged, and the solder particle size was varied between type 3 and type 4. The results show that, with type 4 paste, significantly more solder balls are formed compared to type 3 paste. It was also confirmed that, regarding the reflow profile, the ramp-up rate from 150°C to 217°C and the reflow atmosphere were the most significant factors that determine the solder-ball formation for both types of paste.     

Parameters affecting thermal fatigue behavior of 60Sn-40Pb solder joints

Solder joints in electronic packages experience cyclical thermally induced strain when temperature fluctuations are encountered in service. This study investigates three parameters that affect the microstructure and therefore the thermal fatigue behavior of 60Sn-40Pb solder joints. These parameters are: 1) the effect of a tensile component in thermal fatigue, 2) solder joint thickness variations, and 3) hold time variations at the elevated temperature portion of the thermal cycle. Solder joints were thermally fatigued in a tension/compression deformation mode. Cracks developed both in the interfacial intermetallic layer (early in thermal fatigue) and in the coarsened regions of the microstructure of the solder joint (after many more cycles). The effect of joint thickness on solder joints thermally fatigued in shear was also explored. Solder joint thickness was found not to significantly affect fatigue lifetimes. The effect of an increase in the hold time at the elevated temperature portion of the thermal fatigue cycle was also investigated. It was found that time spent at the high temperature end of the fatigue cycle does not determine solder joint lifetime, rather it is the combination of the amount of deformation induced during thermal fatigue in concert with the elevated temperature.     

焊点的质量与可靠性

主要介绍了Sn—Pb合金焊接点发生失效的各个失效阶段的各种表现形式，探讨发生失效的各种原因．如热应力与热冲击、金属的溶解、基板和元件过热、超声清洗的损害，以及如何在工艺上进行改进以改善焊点的可靠性，使焊点有良好的可靠性、不易损坏，能够承受变化的负载等，从而提高产品的质量。     

Microstructure evolution of eutectic Sn-Ag solder joints

Laser and infrared reflow soldering methods were used to make Sn-Ag eutectic solder joints for surface-mount components on printed wiring boards. The microstructures of the joints were evaluated and related to process parameters. Aging tests were conducted on these joints for times up to 300 days and at temperature up to 190°C. The evolution of microstructure during aging was examined. The results showed that Sn-Ag solder microstructure is unstable at high temperature, and microstructural evolution can cause solder joint failure. Cu-Sn intermetallics in the solder and at copper-solder interfaces played an important role in both the microstructure evolution and failure of solder joints. Void and crack formation in the aged joints was also observed.     

BGA混合焊点热循环负载下的可靠性研究

焊料从有铅向无铅转换中,不可避免会遇到二者混合使用的情况,有必要对生成的混合焊点进行可靠性研究。通过对不同工艺参数下形成的混合焊点和无铅焊点进行了外观检测、X射线检测和温度循环测试。结果显示,只要工艺参数控制得当,混合焊点是可行的。在焊球合金、焊料合金、峰值温度、液相线以上时间和焊接环境五个关键因素中,前四项对焊点可靠性比较重要,焊接环境对焊点可靠性的影响不很显著。     

Sn－Zn－In软钎料合金初步研究

对Ｓｎ－Ｚｎ－Ｉｎ钎料合金的性能进行了研究，钎料铺展性和剪切强度试验结果表明，在Ｓｎ－９Ｚｎ－Ｉｎ软钎料合金中，随Ｉｎ含量增加，铺展面积增大，钎焊接头剪切强度降低。钎料熔点和接头组织等性能的综合分析结果表明Ｓｎ－９Ｚｎ－１０Ｉｎ的性能已接近或超过传统的Ｓｎ－Ｐｂ共晶     

微量Ni对Sn-3.0Ag-0.5Cu钎料及焊点界面的影响

研究了Ni的含量对无铅钎料Sn-3.0Ag-0.5Cu润湿性、熔点、重熔及老化条件下界面化合物(IMC)的影响。结果表明:微量Ni的加入使SnAgCu润湿力增加6%;使合金熔点略升高约3℃;重熔时在界面形成了(Cu,Ni)6Sn5IMC层,且IMC厚度远高于SnAgCu/Cu的Cu6Sn5IMC厚度。在150℃老化过程中,SnAgCuNi/Cu重熔焊点IMC随着时间的增加,其增幅小于SnAgCu/Cu的增幅,此时Ni对IMC的增长有一定抑制作用。     

Characteristics of the Sn-Pb eutectic solder bump formed via fluxless laser reflow soldering

In an attempt to develop a fluxless reflow solder bumping process, the effects of processing variables, which include energy input rate and time, and the shape of solder disk on the microstructure of the solder/Cu pad interface and the shear strength of the joints were investigated. It was demonstrated that a proper combination of the variables could lead to the formation of a spherical solder bump with shear strength comparable to that formed via the conventional reflow soldering process. In addition, the kinetics of Cu pad dissolution into the solder during laser heating was modeled numerically to elucidate intermetallic formation mechanism at the solder/Cu pad interface. Jointly appointed by CAAM at POSTECH