微量稀土元素对Sn3.0Ag0.5Cu无铅焊料合金组织与性能的影响

研究稀土元素对Sn3Ag0.5Cu无铅焊料合金显微组织及性能的影响。结果表明：当稀土含量（wRE）为0.05%~0.25%时,对该无铅焊料合金的导电性和腐蚀性影响不大,但使其熔化区间温度降低;可以提高焊料的铺展面积,细化组织,提高其力学性能。比较Ce、Er、Y、Sc四种稀土元素对焊料合金的影响,发现Ce元素可以更好地提高焊料合金的综合性能,Er次之。

镧对Sn3.5Ag0.5Cu钎料组织性能影响

运用莱卡显微镜、扫描电镜和能谱分析等手段,研究了稀土元素La的添加量对Sn3.5Ag0.5Cu钎料及其与Cu基体焊接后微观组织及性能的影响。结果表明:添加不同含量的稀土La均能使钎料及其与Cu基体焊接后组织与性能得到改善,其中以w(La)达到0.05%时为最优,显微硬度及剪切强度分别提高14%和10.7%。键参数函数计算结果表明La具有"亲Sn"倾向,可细化钎料组织,降低IMC(界面金属间化合物)的长大驱动力。

锌对Sn3.5Ag0.5Cu钎料组织性能的影响

运用莱卡显微镜、X射线衍射仪等仪器设备,研究添加元素Zn对Sn3.5Ag0.5Cu钎料组织性能的影响。结果表明:Zn与Ag、Cu形成AgZn和CuZn3化合物,能显著细化Sn3.5Ag0.5Cu钎料组织,降低Sn3.5Ag0.5Cu钎料合金的润湿性,同时可提高Sn3.5Ag0.5Cu钎料合金抗拉强度。

Influence of bismuth on microstructure,thermal properties,mechanical performance,and interfacial behavior of SAC305−xBiCu solder joints

This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−xBiCu solder joints were investigated.Bi-doping modified the microstructure of the solder joints by refining the primaryβ-Sn and eutectic phases.Bi-doping below 2 wt.%dissolved in theβ-Sn matrix and formed a solid solution,whereas Bi additions equal to or greater than 2 wt.%formed Bi precipitates in theβ-Sn matrix.Solid solution strengthening and precipitation strengthening mechanisms in theβ-Sn matrix increased the ultimate tensile strength and microhardness of the alloy from 35.7 MPa and 12.6 HV to 55.3 MPa and 20.8 HV,respectively,but elongation decreased from 24.6%to 16.1%.The fracture surface of a solder joint containing 2 wt.%Bi was typical of a brittle failure rather than a ductile failure.The interfacial layer of all solder joints comprised two parallel IMC layers:a layer of Cu6Sn5 and a layer of Cu3Sn.The interfacial layer was thinner and the shear strength was greater in SAC305−xBiCu joints than in SAC305Cu solder joints.Therefore,small addition of Bi refined microstructure,reduced melting temperature and improved the mechanical performance of SAC305Cu solder joints.

Combined effects of Bi and Sb elements on microstructure,thermal and mechanical properties of Sn−0.7Ag−0.5Cu solder alloys

This research investigated the combined effects of addition of Bi and Sb elements on the microstructure,thermal properties,ultimate tensile strength,ductility,and hardness of Sn−0.7Ag−0.5Cu(SAC0705)solder alloys.The results indicated that the addition of Bi and Sb significantly reduced the undercooling of solders,refined theβ-Sn phase and extended the eutectic areas of the solders.Moreover,the formation of SbSn and Bi phases in the solder matrix affected the mechanical properties of the solder.With the addition of 3 wt.%Bi and 3 wt.%Sb,the ultimate tensile strength and hardness of the SAC0705 base alloy increased from 31.26 MPa and 15.07 HV to 63.15 MPa and 23.68 HV,respectively.Ductility decreased due to grain boundary strengthening,solid solution strengthening,and precipitation strengthening effects,and the change in the fracture mechanism of the solder alloys.

Thermal reliabilities of Sn−0.5Ag−0.7Cu−0.1Al_(2)O_(3)/Cu solder joint

The effects of trace addition of Al_(2)O_(3) nanoparticles(NPs)on thermal reliabilities of Sn−0.5Ag−0.7Cu/Cu solder joints were investigated.Experimental results showed that trace addition of Al_(2)O_(3) NPs could increase the isotheraml aging(IA)and thermal cyclic(TC)lifetimes of Sn−0.5Ag−0.7Cu/Cu joint from 662 to 787 h,and from 1597 to 1824 cycles,respectively.Also,trace addition of Al_(2)O_(3) NPs could slow down the shear force reduction of solder joint during thermal services,which was attributed to the pinning effect of Al_(2)O_(3) NPs on hindering the growth of grains and interfacial intermetallic compounds(IMCs).Theoretically,the growth coefficients of interfacial IMCs in IA process were calculated to be decreased from 1.61×10^(−10 )to 0.79×10^(−10) cm^(2)/h in IA process,and from 0.92×10^(−10) to 0.53×10^(−10) cm^(2)/h in TC process.This indicated that trace addition of Al_(2)O_(3) NPs can improve both IA and TC reliabilities of Sn−0.5Ag−0.7Cu/Cu joint,and a little more obvious in IA reliability.

Sn-3.5Ag/Cu界面金属间化合物的生长行为研究

研究了Sn-3.5Ag无铅钎料和Cu基体在钎焊和时效过程中界面金属间化合物的形成和生长行为.结果表明,在钎焊过程中,由于钎料中存在着Cu的溶解度,界面处生成的金属间化合物存在着分解现象.因此Sn-3.5Ag/Cu界面金属间化合物层厚度与化合物层的分解有着密切关系.由于吸附作用,金属间化合物表面形成了纳米级的Ag3Sn颗粒.当钎焊接头在70,125,170℃时效时,钎焊时形成的扇贝状金属间化合物转变为层状.金属间化合物的生长厚度与时效时间的平方根呈线性关系,其生长受扩散机制控制.整个金属间化合物层和Cu6Sn5层的生长激活能分别为75.16 kJ/mol,58.59kJ/mol.

Sn-3.0Ag-0.5Cu/Ni/Cu微焊点剪切强度与断口的研究

用直径为200-500μm的Sn-3．0Ag-0．5Cu无铅焊球分别在Ni和Cu焊盘上制作焊点，并对焊后和时效200h后的焊点进行剪切测试，并采用SEM观察剪切断口形貌。结果表明，焊后和时效200h后焊点接头的剪切强度都随焊球尺寸增大而减小。焊后断口处韧窝形状为抛物线型，断裂方式为韧性断裂；随着焊球尺寸的增大，剪切断口处的韧窝数量增多，韧窝的变小变浅。时效200h后，韧窝变浅，趋于平坦，韧窝数量也明显减少，材料的韧性下降，脆性增加，断裂方式由韧性向脆性发生转变。

工业纯Sn和Sn-3Ag-0.5Cu合金在沈阳大气环境下自然暴露的初期腐蚀行为

通过沈阳大气环境下的自然暴露实验研究工业纯Sn和Sn-3Ag-0.5Cu合金的早期大气腐蚀行为。采用扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)分析了表面腐蚀产物的形貌与成分。结果表明:工业纯Sn与Sn-3Ag-0.5Cu合金在沈阳工业大气环境下自然暴露后都很快发生了表面腐蚀并失泽,早期腐蚀产物疏松、龟裂并易于剥落。XPS深度分析表明:自然条件下暴露18 d后,表面腐蚀产物层厚度约为400 nm。工业大气中的悬浮物颗粒对腐蚀的形核和扩展起重要作用,Sn-3Ag-0.5Cu合金中的第二相Ag3Sn和Cu6Sn5作为阴极存在,但对大气腐蚀的加速影响不大。

INTERACTION BETWEEN Cu AND LIQUID Sn(II)——SEM OBSERVATION OF INTERMETALLIC GROWTH

The features of Cu_6Sn_5 growing slowly at lower temperature and growing rapidly up over 350℃,and or Cu_3Sn growing at higher temperatures,bave been detailedly observed under SEM.The increase of Pb content seems to inhibit sequentially the growth of Cu_6Sn_5 in Pb-Sn alloy.

Modification of Sn–1.0Ag–0.5Cu solder using nickel and boron

Effects of Ni and B additions on the microstructure and growth behavior of the intermetallic compound(IMC) of Sn–1.0Ag–0.5Cu alloys(SAC105) were investigated in this study. Results show that microadditions of Ni and B result in volume fraction of primary Sn increasing and the grain size decreasing observably. It is found that a large number of fine reinforcement particles with network-like shape are found in the solder, and the thickness of interfacial IMC layer in the solder joint is grew less than that of SAC105 with longer aging time. Shear test results reveal that as-soldered solder joints of microalloyed SAC105 have better shear strength than that of SAC105 solder alloy.

Effect of Diamond Additions on Wettability and Distribution of SnAgCu Composite Solder

Diamond/SnAgCu composite solder bumps were prepared on Cu pad by mechanically incorporating diamond particles into Sn3.0Ag0.5Cu （SAC） solder powders, mixing with flux and reflowing at 260℃ for 60 s. The spreading areas of composite solder were calculated and the distributions of copper-coated diamonds were characterized. When diamond additions were below 3 wt%, the spreading area decreased with diamond additions, and the diamonds distributed mainly at the interface between solder and Cu pad; however, when additions were beyond 4 wt%, the discharge of diamond particle occurred, and the spreading area increased due to the reduction of surface energy.

Cr对Sn-3.0Ag-0.5Cu无铅焊料抗氧化性能的影响

研究了Cr元素对液态Sn-3.0Ag-0.5Cu(SAC305)焊料在280℃下表面抗氧化性能的影响,并通过扫描电镜(SEM)、俄歇电子能谱(AES)分析了焊料的表面氧化,探讨了Cr改善合金抗氧化性能的机制及其对SAC305无铅焊料显微组织和润湿性能的影响。结果表明,Cr元素的加入可有效提高焊料的抗氧化性,Cr元素在熔融的焊料表面易于生成Cr2O3,其先于Sn氧化形成一种保护性的致密氧化膜,阻碍了焊料的进一步氧化。当焊料中Cr的质量分数达到0.1%(质量分数)时,焊料表面的氧化膜光滑致密,SAC305-0.1Cr液态焊料具有很好的抗氧化性能。另一方面,Cr的加入降低了焊料的润湿性能,随着Cr含量的不断增加,焊料的铺展面积逐渐减少。微量P元素的添加可以改善SAC305-0.1Cr焊料的润湿性。