微量Co对第二代低银SAC焊料合金改性机理研究

目前电子制造业界把低成本的低Ag无铅焊料合金定义为第二代无铅焊料合金。在目前已公开的第二代无铅低Ag焊料合金类型中,又以掺入微量Co改性的应用性能和可靠性表现最优秀而受到了关注。重点对该类型焊料合金掺Co改性的机理展开了研究试验。在研究试验结论的基础上,分析了其推广应用的良好前景。     

阻焊断桥问题原因探究与解决方法

文章主要分析了PCB制造过程中阻焊断桥问题的产生原因,介绍了使用鱼骨图和难度一效益图查找关键影响因素的方法,通过试验,探索出油墨性能,曝光能量,显影速度和压力这几个因素的最佳控制范围。     

电子装联三维结构垂直线和面印刷及回流焊工艺研究

在电子装联领域,焊点通常都位于PCB平面。然而,随着散热、信号屏蔽等要求越来越高,器件及通路的分散性要求焊点能够在三维结构上延伸,从而形成了三维结构的焊点。在回流焊时,垂直(Z轴)方向上的焊料必然要受到重力的影响,特别是在要求连续的线、面焊接时,控制焊料的向下流动是保证焊接质量的难点。针对这一问题,从焊膏性能、印刷工艺和回流工艺三个方面进行分析和实验,不仅获得了连续均匀焊点,而且达到了批量印刷、单次回流的工艺要求,同时减少了器件的热冲击次数。     

Study of thermal cycling and temperature aging on PbSnAg die attach solder joints for high power modules

High power modules are still facing the challenges to increase their power output, increase the junction temperature, and increase their reliability in harsh conditions. Therefore this study is doing a detail analysis of the soldering joint between a direct copper bonded substrate and a high power IGBT made with the high lead solder alloy Pb_92.5Sn_5.0Ag_2.5. The intermetallic phases and the microstructure of standard chip to substrate solder joint will be analysed and compared to deteriorated joints coming from modules which have undergone an active thermal cycling. As expected, the as soldered joint was clearly different than solder joints made for ball grid array or small components on PCBs. The as soldered joint shows no sign of Cu₆Sn₅ intermetallic layer, but instead shows the presence of Ag₃Sn particles at the solder–chip interface. Furthermore, the failure mechanisms under active thermal cycling also seem to be different. There is no growth of intermetallic phases and no strong delamination of the device. Instead a large network of intermetallic particles (Ag₃Sn) is produced during aging and seems to degrade the solder thermal properties.     

STEPPER通用测试掩模的设计及使用

介绍了一种ＳＴＥＰＰＥＲ通用测试掩模（ＵＴＭ）的设计构成及各测试元素图形的作用。在此基础上，分析了电子束制作ＵＴＭ的误差，并阐述了ＵＴＭ的测试方法、数据处理及其对ＳＴＥＰＰＥＲ性能的影响。     

SMT细间距工艺技术研究

从ＰＣＢ设计，漏印模板设计与制造，焊膏应用以及组装工艺等方面。讨论了细间距ＳＭＴ工艺技术，提出相应的对策，这对提高细间距器件的焊接质量具有普遍意义。     

Adhesion force change on multilayer EUVL mask due to laser induced plasma shock wave

Change in adhesion force between a borosilicate glass microsphere and 40 Al₂O₃/TaN/Ru/MoSi pairs on a silicon wafer used as a multilayer extreme ultraviolet lithography mask stack were characterized by force-distance spectroscopy after cleaning Al₂O₃ layers using a laser induced plasma (LIP) shock wave. The adhesion force of the Al₂O₃ surface decreased at a higher laser energy and a lower gap distance above a threshold gap distance without changes in surface roughness. Frictional electrostatic repulsion, triboelectricity, was identified as the cause of lower adhesion forces on Al₂O₃ surface due to the high velocity and pressure of the LIP shock waves. The adhesion force decreased by increasing the number of exposures of LIP shock waves to the substrate.     

Finite element modeling of thermal fatigue and damage of solder joints in a ceramic ball grid array package

A nonlinear finite element model is presented for analyzing the cyclic and thermal fatigue loading and for viscoplastic damage characterization of the lead-tin (Pb-Sn) solder joints in a ceramic ball grid array (CBGA) surface mount package. An approach using a Δ ∈ _eq ⁱⁿ -modified Coffin-Manson equation is proposed to estimate the fatigue life of the solder joints. The Δ ∈ _eq ⁱⁿ represents a saturated equivalent inelastic strain range as determined by the finite element model. The present study shows that the predictied fatigue life and the associated damage mechanism of the solder joint agree reasonably well with the test data for the 18,25, and 32 mm CBGA packages run at a cyclic temperature load of 0°C/100°C with a frequency of 1.5 cycles per hour. Analysis also shows that a preferred failure site is expected to occur in and around the Pb37-Sn63 solder attachment of the solder joint. A time-dependent (creep induced) damage mechanism is found to be more pronounced than the time-independent (plastic deformation) mechanism.     

光纤光栅技术的进展及其色散补偿

光纤光栅在远程光通信系统中有着重要的现时和潜在的应用。文章介绍了制造具有复杂结构的光纤光栅的技术的最新进展以及它们在色散补偿中的应用，并指出了其发展趋势。     

进口松香型焊膏的成分分析

本文采用离心分离的方法沉淀出松香型焊膏的无机组分，并用发射光谱测定无机成分；优选了氯仿：95％乙醇：25氨水：水＝35：30：2：2（体积比）作为焊膏有机组分的薄层色谱展开剂，在薄层板上呈现清晰的4个斑点，以此展开剂作为柱色谱的流动相，成功地分离了各种有机组分，并采用红外、质谱等手段鉴定了所含组分的结构。