共查询到20条相似文献,搜索用时 31 毫秒
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Hong Chang Hongtao Chen Mingyu Li Ling Wang Yonggao Fu 《Journal of Electronic Materials》2009,38(10):2170-2178
The effect of the anode and cathode on the electrochemical corrosion behavior of lead-free Sn-Ag-Cu and Sn-Ag-Cu-Bi solder
joints in deionized water was investigated. Corrosion studies indicate that SnO crystals were generated on the surfaces of
all lead-free solder joints. The constituents of the lead-free solder alloys, such as Ag, Cu, and Bi, did not affect the corrosion
reaction significantly. In contrast to lead-free solders, PbO
x
was formed on the surface of the traditional 63Sn-37Pb solder joint in deionized water. A cathode, such as Au or Cu, was
necessary for the electrochemical corrosion reaction of solders to occur. The corrosion reaction rate decreased with reduction
of the cathode area. The formation mechanism of SnO crystals was essentially a galvanic cell reaction. The anodic reaction
of Sn in the lead-free solder joints occurred through solvation by water molecules to form hydrated cations. In the cathodic
reaction, oxygen dissolved in the deionized water captures electrons and is deoxidized to hydroxyl at the Au or Cu cathode.
By diffusion, the anodic reaction product Sn2+ and the cathodic reaction product OH− meet to form Sn(OH)2, some of which can dehydrate to form more stable SnO·xH2O crystals on the surface of the solder joints. In addition, thermodynamic analysis confirms that the Sn corrosion reaction
could occur spontaneously. 相似文献
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通过大量的数据信息分析了各研究机构在无铅焊料方面的研究成果,在目前流行使用的无铅焊料的基础上,进一步研究并比较了其中的Sn-Cu系列与具有专利限制的SnAgCu系列焊料在消费类电子产品组装的波峰焊工艺中使用的可靠性,同时研究并比较Sn-Ag系列焊料与SnAgCu系列焊料在回流焊工艺使用的情况。结果表明,Sn-Cu共晶焊料在消费类电子产品组装的波峰焊工艺中完全可以取代Sn-Ag-Cu系列焊料,同时满足使用要求;而同样技术成熟的Sn-Ag共晶焊料也完全可以取代SnAgCu系列焊料在回流焊工艺使用,焊点的可靠性与成本可以媲美SnAgCu焊料。而且该二元合金在使用维护以及回收利用方面具有相当的优势。 相似文献
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D. Ro
ak S. Ma
ek J. Sitek M. Hrovat K. Bukat Z. Drozd 《Microelectronics Reliability》2007,47(6):986-995
The results of the influence of lead-free solder paste, design and process parameters on the attachment reliability of chip surface-mounted components (SMCs) on thick-film conductor pads are presented. The purpose of the investigation was to compare the quality of the soldered joints made with new solder pastes that do not contain lead with joints soldered with standard SnPb solders. The miniature zero-ohm chip resistors were soldered with selected lead-free solder pastes. The visual appearance of the solder joint according to the standards of lead-free soldered components was compared with components soldered with SnPb solders. On the test sample with soldered chip resistors connected in series, the solder-joint resistance was measured before and after temperature cycling. On the same test sample the solder-joint resistance changes were measured with impedance spectroscopy. After temperature cycling the damaged samples were analysed with SEM and EDS. The reliability test results after temperature cycling indicate two lead-free solder pastes that are the most convenient for chip-component soldering on thick-film conductor pads with the reliability of the joints being equal or better than solder joints with Pb-containing solder paste. 相似文献
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Evaluation of Lead- Free Solder Joints in Electronic Assemblies 总被引:2,自引:0,他引:2
The feasibility of printed circuit board assembly with lead-free solder alloys was investigated. Studies were conducted with
two baseline eutectic binary alloys, SnBi and SnAg, and three new lead-free solder formulations: (1) 91.8Sn-4.8Bi-3.4Ag (wt%)
developed at Sandia Laboratories, (2) 77.2Sn-20In-2.8Ag developed at Indium Corp. of America, and (3) 96.2Sn-2.5Ag-0.8Cu-0.5Sb
provided by AIM Inc. The basic physical properties (melting temperature, wetting, mechanical strength) pertinent to each of
the newly developed alloys are described. The feasibility of 0.4 mm pitch assembly was established with each of the lead-free
solder alloys investigated, although the processing windows were generally found to be narrower. All solder joints exhibited
good fillets, in accordance with the workmanship standards. Wetting of the lead-free solders was significantly improved on
immersion tin vs imidazole finished circuit boards. The laminates did not suffer thermal degradation effects, such as warpage,
delamination, or severe discoloration (reflow was performed under an inert atmosphere). It is thus concluded that the manufacturability
performance of the new solder formulations is adequate for surface mount applications. 相似文献
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As the electronics industry is moving towards lead-free manufacturing processes, more effort has been put into the reliability study of lead-free solder materials. Various tin–silver–copper-based solders have become widely accepted alternatives for tin–lead solders. In this study, we have tested three different SnAgCu solder compositions. The first consisted of a hypoeutectic 96.5Sn/3.0Ag/0.5Cu solder, the second of a eutectic 95.5Sn/3.8Ag/0.7Cu solder, and the third of a hypereutectic 95.5Sn/4.0Ag/0.5Cu solder. A eutectic SnPb solder was used as a reference. The test boards were temperature-cycled (−40 to +125 °C) until all samples failed. The results of the temperature cycling test were analyzed, and cross-section samples were made of the failed joints. Scanning electron and optical microscopy were employed to analyze the fracture behavior and microstructures of the solder joints. The reliability of lead-free solders and the effect of microstructures on joint reliability are discussed. 相似文献
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JIS Z 3198无铅钎料试验方法简介与评述 总被引:30,自引:5,他引:25
JIS Z 3198是关于无铅钎料及其接合部性能测试的工业标准,由日本焊接协会提出初始提案,经日本工业标准调查会审议,最终由日本经济产业省于2003年6月20日并发布.标准涵盖了无铅钎料熔化温度范围测试、机械特性测试、铺展性测试、润湿性测试、接头的拉伸与剪切强度测试、QFP引线软钎焊接头拉引测试、片式元件软钎焊接头的剪切测试7个方面.依据JIS Z 3198 1-7原文对该标准各部分进行介绍,拟推进我国电子封装与组装的无铅化进程. 相似文献
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采用悬滴法测量了3种无铅钎料合金(Sn-3.0Ag-0.5Cu、Sn-0.7Cu与Sn-9.0Zn)在260℃时的表面张力,分别为525.5,534.8和595.4 mN/m;同时采用座滴法测量了其在260℃熔融状态下与Cu基板的接触角,分别为24.5°、28.0°和102.5°,并且与传统Sn-37.0Pb钎料进行了比较研究。结果表明,无铅钎料合金的表面张力与接触角均大于Sn-37.0Pb钎料。结合Young-Dupre公式讨论了钎料合金表面张力与其润湿性能的相关性,认为Sn基钎料合金在Cu基板上的润湿性能主要取决于其表面张力。 相似文献
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Development of nano-composite lead-free electronic solders 总被引:1,自引:0,他引:1
Inert, hybrid inorganic/organic, nano-structured chemicals can be incorporated into low melting metallic materials, such as
lead-free electronic solders, to achieve desired levels of service performance. The nano-structured materials technology of
polyhedral oligomeric silsesquioxanes (POSS), with appropriate organic groups, can produce suitable means to promote bonding
between nano-reinforcements and the metallic matrix. The microstructures of lead-free solder reinforced with surface-active
POSS tri-silanols were evaluated using scanning electron microscopy (SEM). Wettability of POSS-containing lead-free solders
to copper substrate was also examined. Steady-state deformation of solder joints made of eutectic Sn-Ag solder containing
varying weight fractions of POSS of different chemical moieties were evaluated at different temperatures (25°C, 100°C, and
150°C) using a rheometric solids analyzer (RSA-III). Mechanical properties such as shear stress versus simple shear-strain
relationships, peak shear stress as a function of rate of simple shear strain, and testing temperature for such nano-composite
solders are reported. The service reliability of joints made with these newly formulated nano-composite solders was evaluated
using a realistic thermomechanical fatigue (TMF) test profile. Evolution of microstructures and residual mechanical property
after different extents of TMF cycles were evaluated and compared with joints made of standard, unreinforced eutectic Sn-Ag
solder. 相似文献
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相对于传统的Sn-Pb焊料,无铅焊料更容易氧化,润湿性较差,从而影响波峰焊接质量.N2保护可以降低无铅焊料的氧化,提高无铅焊料的润湿性,从而提高波峰焊接质量.从润湿性的机理分析了N2保护提高无铅焊料润湿性的原因,并通过润湿性实验和波峰焊接试验证实了N2保护的优越性. 相似文献
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相对于传统的Sn—Pb焊料,无铅焊料需要较高的焊接温度,而且润湿性差,另外免清洗助焊剂和水溶性助焊剂的固体含量低,活性温度高和活性区间窄。无铅焊料和助焊剂的特性决定了无铅波峰焊设备在结构和材料选用上有很大不同。本文通过对无铅波峰焊设备的各个部分的特点进行分析,为传统的旧波峰焊设备的改造提供参考。 相似文献
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Masazumi Amagai Masako Watanabe Masaki Omiya Kikuo Kishimoto Toshikazu Shibuya 《Microelectronics Reliability》2002,42(6):951-966
Recently, preventing environmental pollutions, lead-free (Pb-free) solders are about to replace tin–lead (Sn–Pb) eutectic solders. However, the mechanical properties of Pb-free solders have not been clarified. Hence, the following study was conducted; first, a rate-dependent plasticity was characterized to represent the inelastic deformation behavior for Sn–Ag-based lead-free solders. The material parameters in a constitutive model were determined in a direct method combining both rate-dependent and rate-independent plastic strains. The constitutive model unifies both rate-dependent creep behavior and rate-independent plastic behavior occurring concurrently at the same time in the solders. Secondly, the strength of solders with a variety of plating materials was studied. Intermetallic compounds (IMC) between solder and electrical pads are formed during reflow process and gradually grow in service. By using the Cu-plates on which Cu or Ni or Ni/Au plating was deposited, the specimens of solder joints were fabricated with Sn–Ag-based lead-free solders. After aging the specimens in an isothermal chamber, tensile tests were performed. From scanning electron microscope (SEM) microscope observation and EDX microprobe analysis, the growth and components of the IMC layer were also examined. Based on the experimental tests, the relations between solder joint strength and the aging period were discussed. Furthermore, the validation of fracture strength of solder joints resulting from the tensile tests was verified with package-mounted board level reliability tests. 相似文献
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Effects of thermomechanical cycling on lead and lead-free (SnPb and SnAgCu) surface mount solder joints 总被引:1,自引:0,他引:1
Accelerated reliability tests have been performed on leadless and leaded lead-free and lead containing SMT component assemblies. Results so far have shown that lead-free reflow soldering is a viable alternative for conventional lead based reflow soldering. The selected ternary eutectic solder alloy SnAg3.8Cu0.7 requires higher processing temperatures which could restrict the use of certain board and component types, but other than that no major modifications seem necessary. Although better SnAg3.8Cu0.7 bulk mechanical properties were obtained compared to the near eutectic lead bearing bulk solder properties, reflowed solder joints did not reflect this difference. In general, quite similar reliability results were obtained as found for the lead based solders. Dependent on board and component metallisations and use environment, the reliability of the lead-free solders could perform better or worse than the lead based solders. Temperature dependent aspects such as solderability and mechanical behaviour of the lead-free assemblies could play a role in this. Although microstructural differences can be seen between the lead-free and lead bearing solder joints, similar joint failure mechanisms occur. Resistor solder joint cracks propagate from underneath the component through either transgranular (lead-free) grains or along intergranular (lead) grain boundaries between lead-rich and tin-rich areas and into coarsened regions near the component terminations. Gullwing lead cracks were seen propagating from the heel fillet along the lead/solder interfacial intermetallic mostly (some cracks started in the heel fillet and propagated through the solder body dispersed with coarsened spherical Ag3Sn intermetallic particles). Package design and leadframe material seem to play a more important role in the fatigue mechanism than the change in microstructure of the solder joint. 相似文献
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无铅波峰焊设备的特点 总被引:1,自引:0,他引:1
相对于传统的Sn-Pb焊料,无铅焊料需要较高的焊接温度,而且润湿性差,另外免清洗助焊剂和水溶性助焊剂的固体含量低,活性温度高和活性区间窄。无铅焊料和助焊剂的特性决定了无铅波峰焊设备在结构和材料选用上有很大不同。通过对无铅波峰焊设备的各个部分的特点进行分析,为传统的旧波峰焊设备的改造提供参考。 相似文献
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E.H. Wong C.S. Selvanayagam S.K.W. Seah W.D. van Driel J.F.J.M. Caers X.J. Zhao N. Owens L.C. Tan D.R. Frear M. Leoni Y.-S. Lai C.-L. Yeh 《Journal of Electronic Materials》2008,37(6):829-836
The stress–strain properties of eutectic Sn-Pb and lead-free solders at strain rates between 0.1 s−1 and 300 s−1 are required to support finite-element modeling of the solder joints during board-level mechanical shock and product-level
drop-impact testing. However, there is very limited data in this range because this is beyond the limit of conventional mechanical
testing and below the limit of the split Hopkinson pressure bar test method. In this paper, a specialized drop-weight test
was developed and, together with a conventional mechanical tester, the true stress–strain properties of four solder alloys
(63Sn-37Pb, Sn-1.0Ag-0.1Cu, Sn-3.5Ag, and Sn-3.0Ag-0.5Cu) were generated for strain rates in the range from 0.005 s−1 to 300 s−1. The sensitivity of the solders was found to be independent of strain level but to increase with increased strain rate. The
Sn-3.5Ag and the Sn-3.0Ag-0.5Cu solders exhibited not only higher flow stress at relatively low strain rate but, compared
to Sn-37Pb, both also exhibited higher rate sensitivity that contributes to the weakness of these two lead-free solder joints
when subjected to drop impact loading. 相似文献