Tensile deformation behavior of nano-sized Mo particles reinforced SnAgCu solders

In this work, tensile deformation of Sn-3.8Ag-0.7Cu (SAC387) solder and composite of SAC387 reinforced with nano-sized Mo particles have been studied with strain rates from 10⁻⁵ to 10⁻¹ s⁻¹ and temperatures of 25, 75 and 125 °C. It is found that the yield strength (σ_Y.S) and strain hardening exponent (n) are increased with the strain rate, but the n values decrease with increasing temperatures. The n values of the composite solder are also increased with the percentage of the Mo nano-particles (up to 1 wt.%) and thereafter decrease with further increasing of the Mo particle. The strain rate dependence of the Hollomon parameters is found to be stronger at higher temperatures for SAC387 solder, but it is weaker for the composite solders. Empirical equations for σ_Y.S and Hollomon parameters with strain rate and temperatures have been found for both SAC387 and composite solders. Finally, the fracture surfaces of the solders are examined.     

SnAgCu无铅焊膏可印刷性及焊点微观结构研究

焊膏的印刷质量及焊点的微观结构直接影响产品的最终性能和使用效果.通过对焊膏印刷性能及焊点微观结构的研究,可以制定出合适的印刷和焊接工艺,从而提高产品的最终性能和使用效果.本文以紧耦合气雾化法制备的SnAgCu合金粉末为原料,对不同质量配比下焊膏的流变和塌陷性能以及焊点的微观结构进行研究,采用旋转流变仪和扫描电镜分别对焊...     

急冷型SnAgCu系钎料合金钎焊工艺及接头性能研究

制备了急冷型SnAgCu系钎料合金,在对其进行熔化特性测定和钎焊工艺试验后,对钎焊接头的力学性能和显微组织进行了测试分析,结果表明:所制备钎料合金的熔化特性满足要求;钎焊温度和钎焊时间对接头的剪切强度有较大影响,工艺参数为275℃×4.5min时,接头强度最高;在钎焊过程中形成的金属间化合物沿界面分布不均匀,且向钎焊缝中生长.     

SnAgCu系无铅钎料合金力学性能及钎焊性能研究

利用光学显微镜、扫描电子显微镜(SEM)和能谱分析仪(EDX)及Instron电液伺服疲劳拉伸试验机,对SnAgCu系无铅钎料合金的力学性能和钎焊性能进行了研究.结果表明,适量的稀土元素Ce的添加显著地延长了Sn3Ag2.8Cu钎焊接头在室温下的蠕变断裂寿命,Sn3Ag2.8Cu-0.1Ce钎焊接头的蠕变断裂寿命超过Sn3Ag2.8Cu钎料的9倍;同时,使Sn3Ag2.8Cu合金的延伸性能也得到了显著改善,伸长率达到15.7%;Sn3Ag2.8Cu-0.1Ce与铜基板的扩散层厚度比Sn37Pb厚,但是比Sn3Ag2.8Cu薄.     

工艺参数对急冷型SnAgCu系钎料合金钎焊接头组织性能的影响

对所制备的急冷型snAgCu系钎料合金进行了熔化温度特性测定和钎焊工艺试验,然后对钎焊接头的力学性能和显微组织进行了测试分析,并研究了钎焊工艺参数对接头组织性能的影响.结果表明:在不同的钎焊温度和钎焊时间奈件下,接头界面处金属间化合物的形成及分布是不同的,并由此导致了接头抗剪强度的变化.     

微乳法制备参数对纳米锡银铜焊粉熔点的影响

用微乳法制备低熔点纳米锡银铜焊粉并揭示其机理,研究了表面活性剂、锡前驱体和微乳液比例对合成的纳米SAC粒子熔点的影响。在最优工艺参数条件下合成的纳米Sn3.0Ag0.5Cu其熔化起始温度为183.6℃,比市售焊锡膏(217.8℃)降低了32.2℃,与传统Sn-Pb焊料的最低熔点183℃接近。     

Damage Behavior of SnAgCu Solder under Thermal Cycling

电子封装焊点的热循环失效是焊点材料损伤逐步发展的结果,本工作旨在对SnAgCu钎料的热循环损伤失效行为进行研究.以连续损伤力学理论为基础,提出了一种适用于热循环条件下SnAgCu钎料蠕变-疲劳交互作用的损伤模型.据此,设计了热力循环实验和热循环实验用以标定损伤模型相关参量.自行设计了双金属剪切加载装置并结合温度循环实验,对SnAgCu钎料的热力耦合损伤行为进行了深入研究.以电阻变化率作为损伤变量,并在热循环的不同周次测量试样的损伤值从而验证损伤模型.结果表明:所提出的幂函数形式的损伤模型能较好的描述SnAgCu钎料的热循环损伤演变.最后,对热循环条件下SnAgCu钎料试样的微观组织演变进行了SEM分析,从而揭示其损伤演变机理.     

稀土相RE-Sn表面Sn晶须的生长规律

将稀土相CeSn3、LaSn3、(La0.4Ce0.6)Sn3及ErSn3暴露于空气中,研究在时效处理过程中其表面Sn晶须的生长规律。结果表明:室温时效过程中,在稀土相的表面均出现了Sn晶须的生长现象,且稀土相LaSn3的表面倾向于形成包状和扭结状的Sn晶须,稀土相CeSn3和(La0.4Ce0.6)Sn3的表面倾向于形成针状和扭结状的Sn晶须,而稀土相ErSn3的表面倾向于形成大尺寸的杆状和棒状Sn晶须。150℃时效过程中,稀土相CeSn3、LaSn3和(La0.4Ce0.6)Sn3的表面没有出现Sn晶须的生长现象,而稀土相ErSn3的表面出现了大量的小尺寸线状Sn晶须。综上所述,稀土相的氧化倾向决定了其表面Sn晶须的生长规律。     

Interfacial reaction and elemental redistribution in Sn3.0Ag0.5Cu-xPd/immersion Au/electroless Ni solder joints after aging

Sn3.0Ag0.5Cu solder doped with 0, 100, and 500 ppm Pd was reflowed with electroless Ni/immersion Au substrate. As Pd concentration increased in the solder, formation and growth of (Cu,Ni)₆Sn₅ were suppressed. After thermal aging, Cu₄Ni₂Sn₅ and Cu₅NiSn₅ were observed at interface of Sn3.0Ag0.5Cu-xPd/Au/Ni systems. As compared to Cu₄Ni₂Sn₅, more Pd dissolved in Cu₅NiSn₅. In addition, Pd doping enhanced the growth of Cu₄Ni₂Sn₅ and slowed the formation of Cu₅NiSn₅, which would stabilize the intermetallic compound. Based on quantitative analysis by field emission electron probe microanalyzer, the correlation between Pd doping and elemental redistribution in solder joints was probed and discussed. This study described a possible mechanism of the formation of different intermetallic compounds in Pd-doped lead-free solder.