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。     

钎焊时间对Sn-3.0Ag-0.5Cu/Cu钎焊接头界面化合物的影响

研究了不同钎焊时间下Sn-3.0Ag-0.5Cu/Cu焊点界面金属间化合物生长变化规律和剪切强度变化。结果表明:随着钎焊时间增加,界面化合物平均厚度逐渐增加,且生长的时间指数为0.4。钎焊60s内界面化合物的生长速率较大;随着钎焊时间的增加,钎焊接头的抗剪切强度先增加后降低,这与界面处脆硬相Cu6Sn5生长行为密切相关。     

Fe粉对Sn-3Ag-0.5Cu复合钎料组织及性能的影响

通过在钎料中添加Fe粉颗粒,研究其对Sn-3Ag-0.5Cu复合无铅钎料的黏度、熔点、钎焊接头界面微观组织、与Cu基板之间的润湿性及焊点力学性能的影响。结果表明:微米级Fe粉的添加增加了复合钎料焊膏单位体积内焊粉的接触面积,使得焊膏内摩擦力增大,导致复合钎料焊膏的黏度增加;微米级Fe粉的添加对Sn-3Ag-0.5Cu钎料的熔化特性没有显著影响;钎焊时,由于重力偏聚及界面吸附作用,Fe粉颗粒集中沉积于Sn-3Ag-0.5Cu-Fe/Cu钎焊接头界面处靠近钎料一侧,由于增大液态钎料黏度而导致钎料与Cu板间的润湿性降低;与Sn-3Ag-0.5Cu/Cu相比,Sn-3Ag-0.5Cu-Fe/Cu界面处钎料一侧粗大的β-Sn枝晶区消失,取而代之的是细小的等轴晶。Sn-3Ag-0.5Cu-1%Fe/Cu的剪切强度为46 MPa,比Sn-3Ag-0.5Cu/Cu剪切强度提高39%;靠近界面金属间化合物处钎料基体的显微硬度提高约25%。     

SnAgCu/Cu和SnPb/Cu界面热-剪切循环条件下化合物的生长行为

对热剪切循环条件下Sn-3.5Ag-0.5Cu/Cu和Sn-Pb/Cu界面上原子扩散和化合物的生长行为进行了研究。结果表明:再流焊后,在两界面上均形成一种Cu6Sn5化合物;随着热剪切循环周数的增加,两界面上化合物的形态均从扇贝状向层状生长,其厚度随循环周数的增加而增加,且生长基本遵循抛物线规律,说明Cu原子的扩散控制了Cu6Sn5化合物的生长。界面近域的钎料内,颗粒状的Ag3Sn聚集长大成块状。     

等温时效中稀土Er对Sn-3.8Ag-0.7Cu无铅钎料显微组织演化的影响

系统研究了等温时效中添加微量稀土Er对Sn-3.8Ag-0.7Cu钎料合金显微组织演化规律的影响.结果表明,Er对Sn-3.8Ag-0.7Cu钎料显微组织及等温时效过程中显微组织的演化产生了重要影响.在钎焊过程中,Er有效地细化了钎料组织,改变了钎料内部Cu-Sn金属间化合物的形态、尺寸及分布情况.在等温时效过程中,钎料内部生成的ErSn3金属间化合物为组织的再结晶过程提供了大量的形核质点,有效避免了再结晶组织的粗化及裂纹的产生和扩展.     

Sn-3.0Ag-0.5Cu-xNi无铅焊料及焊点的性能

研究了Ni元素对Sn-3.0Ag.0.5Cu无铅钎料熔点、润湿性、拉伸性能及焊点性能的影响.结果表明,镍的添加对Sn-3.OAg-0.5Cu钎料的润湿性有所改善,添加量为0.03%～0.1%时,随着镍含量的增加,润湿时间逐渐递减,润湿力逐渐增大,镍含量在0.05%时润湿时间最短,镍含量在O.1%时润湿力最大.但当镍含量到0.15%时,润湿时间反而增长,润湿力下降;镍提高了合金的抗拉强度、断后伸长率及焊点的抗剪强度.当镍含量为0.05%时,抗拉强度最高,当镍含量为0.1%时,断后伸长率和抗剪强度最高,扫描断口表现为明显的韧性断裂特征;镍的添加量为0.05%~0.1%效果较好.     

镀镍多壁碳纳米管对Sn-3.0Ag-0.5Cu无铅钎料焊点界面行为的影响

采用机械混合法制备了不同含量(0、0.05、0.1、0.2、0.5wt%)镀镍多壁碳纳米管(Ni-CNTs)复合Sn-3.0Ag-0.5Cu(SAC305)无铅钎料。采用F4N回流炉对SAC305-x(Ni-CNTs)钎料进行回流焊,利用电热鼓风干燥箱对焊点试样进行170 ℃时效(t=0、48 h)处理。结合DTA、SEM、EDS等分析手段研究了不同镀镍碳纳米管含量对Sn-3.0Ag-0.5Cu钎料润湿性、熔点和焊点界面金属间化合物(IMC)层的影响。结果表明:Ni-CNTs可以显著改善钎料的润湿性,降低钎料熔点;此外,Ni-CNTs可以有效抑制界面IMC层的生长,同时改变界面IMC组成。综合比较得出Ni-CNTs最佳添加量为0.05%,与Sn-3.0Ag-0.5Cu钎料相比,润湿角降低49.76%,熔点降低0.331 ℃;时效后界面IMC层厚度4.292 μm(t=0 h)、5.238 μm(t=48 h)相对于SAC305钎料界面IMC厚度6.529 μm(t=0 h)、8.255 μm(t=48 h)分别降低了34.26%(t=0 h)、36.55%(t=48 h),界面IMC层相组成转变为(Cu_1-xNi_x)₆Sn₅和(Cu_1-xNi_x)₃Sn。     

Co对Sn-3.0Ag-0.5Cu钎料接头显微组织和服役可靠性的影响

研究了高温对SnAgCu+xCo(x=0,0.1,0.2,0.45,1.0,x为质量分数%,下同)复合钎料接头显微组织和力学性能的影响。用差热分析法(DSC)分析了Co对钎焊接头过冷度和凝固相的影响。与Sn-3.0Ag-0.5Cu钎料相比,焊后SnAgCu+xCo(x=0.1,0.2)复合钎料界面金属间化合物层厚度减小,接头剪切强度提高。经150℃保温500h后,SnAgCu+xCo复合钎料接头剪切强度均高于Sn-3.0Ag-0.5Cu钎料接头,说明Co的添加可以改善SnAgCu钎料的服役可靠性。经DSC分析,Co的添加会提高SnAgCu钎料合金的凝固点,从而降低其过冷度。综上,Sn-3.0Ag-0.5Cu-0.2Co复合钎料接头的力学性能和服役条件下的可靠性最佳。     

热-剪切循环条件下Sn-3．5Ag-0．5Cu／Cu（Ni）界面化合物生长行为研究

对热-剪切循环条件下Sn-3．5Ag-0．5Cu钎料在Cu和Ni界面上原子扩散和化合物的生长行为进行了研究。结果表明：再流焊后，在Sn-3．5Ag-0．5Cu／Ni界面上形成（CuxNi1-x）6Sn5化合物；热-剪切循环200周次后，（NixCu1-x）Sn3化合物在（CuxNi1-x）6Sn5化合物周围以片状快速长大；而Sn-3．5Ag-0．5Cu／Cu界面从钎焊到热-剪切循环720周次始终只存在Cu6Sn5金属化合物层。随着热-剪切循环周数的增加，（CuxNi1-x）6Sn5和Cu6Sn5化合物形态均从笋状向平面状生长。界面金属间化合物的厚度随循环周数的增加而增加，且生长基本遵循抛物线规律，说明Cu原子的扩散控制了（CuxNi1-x）6Sns和Cu6Sn5化合物的生长。     

Electrochemical corrosion behaviour of Pb-free Sn-8.5Zn-0.05Al-XGa and Sn-3Ag-0.5Cu alloys in chloride containing aqueous solution

The electrochemical corrosion behaviour of Pb-free Sn-8.5Zn-0.05Al-XGa and Sn-3Ag-0.5Cu alloys was investigated in 3.5% NaCl solution by using potentiodynamic polarization techniques. The results obtained from polarization studies revealed that there was a negative shift in the corrosion potential with increase in Ga content from 0.02 to 0.2 wt% in the Sn-8.5Zn-0.05Al-XGa alloy. These changes were also reflected in the corrosion current density (I_corr) value, corrosion rate and linear polarization resistance (LPR) of the four element alloy. However, for Sn-3Ag-0.5Cu alloy a significant increase in the corrosion rate and corrosion current density was observed as compared to the four element alloys. SIMS depth profile results established that ZnO present on the outer surface of Sn-8.5Zn-0.05Al-0.05Ga alloy played a major role in the formation of the oxide film. Oxides of Sn, Al and Ga contributed a little towards the formation of film on the outer surface of the alloy. On the other hand, Ag₂O was primarily responsible for the formation of the oxide film on the outer surface of Sn-3Ag-0.5Cu alloy.     

Pr,Nd对Sn0.3Ag0.7Cu0.5Ga无铅钎料显微组织的影响

分析了添加两种稀土元素Pr,Nd对Sn-0.3Ag-0.7Cu-0.5Ga无铅钎料基体组织、焊点界面组织的影响并测定了焊点抗剪强度.结果表明,在该钎料中分别添加Pr,Nd元素可以改善钎料的显微组织,且加入Pr元素的效果优于Nd.添加Pr元素的钎料基体组织中金属间化合物分布均匀,而后者易在晶界处产生“区域”状金属间化合物,成为裂纹的发源地.稀土元素的吸附作用可以降低钎料与铜基板界面反应的剧烈程度,从而改善界面的形貌.添加Pr元素的钎料可以更好地与铜基板结合,从而提高了焊点的抗剪强度.     

Wetting of molten Sn-3.5Ag-0.5Cu on Ni-P(-SiC) coatings deposited on high volume faction SiC/Al composite

The wetting of molten Sn-3.5Ag-0.5Cu alloy on the Ni-P(-SiC) coated SiC_p/Al substrates was investigated by electroless Ni plating process, and the microstructures of the coating and the interfacial behavior of wetting systems were analyzed. The SiC particles are evenly distributed in the coating and enveloped with Ni. No reaction layer is observed at the coating/SiC_p/Al composite interfaces. The contact angle increases from ～19° with the Ni-P coating to 29°, 43° and 113° with the corresponding Ni-P-3SiC, Ni-P-6SiC and Ni-P-9SiC coatings, respectively. An interaction layer containing Cu, Ni, Sn and P forms at the Sn-Ag-Cu/Ni-P-(0,3,6)SiC coated SiC_p/Al interfaces, and the Cu-Ni-Sn and Ni-Sn-P phases are detected in the interaction layer. Moreover, the molten Sn-Ag-Cu can penetrate into the Ni-P(-SiC) coatings through the Ni-P/SiC interface and dissolve them to contact the SiC_p/Al substrate.     

稀土Pr对Sn-0.3Ag-0.7Cu钎料润湿性能和微焊点力学性能的影响

采用润湿平衡法研究了微量稀土Pr元素对Sn-0.3Ag-0.7Cu在Cu基板上润湿性能的影响规律,并借助STR-1000型微焊点强度测试对Sn-0.3Ag-0.7Cu-x Pr微焊点的力学性能。结果表明,随着稀土Pr含量的增加,钎料在Cu基板上的润湿力逐渐增加,润湿时间缩短。当Pr的质量分数在0.05%~0.1%时,Sn-0.3Ag-0.7Cu-x Pr钎料的润湿性能最好。在260℃的试验条件下,Sn Ag Cu-0.1Pr相比Sn Ag Cu钎料润湿力提高了5.0%,润湿时间降低了16.9%。且当Pr含量约为0.05%时,微焊点的力学性能最佳,焊点的剪切强度提高了8.5%。     

Interfacial Reactions and Bonding Strength of Sn-xAg-0.5Cu/Ni BGA Solder Joints

The present study details the microstructure evolution of the interfacial intermetallic compounds (IMCs) layer formed between the Sn-xAg-0.5Cu (x = 1, 3, and 4 wt.%) solder balls and electroless Ni-P layer, and their bond strength variation during aging. The interfacial IMCs layer in the as-reflowed specimens was only (Cu,Ni)₆Sn₅ for Sn-xAg-0.5Cu solders. The (Ni,Cu)₃Sn₄ IMCs layer formed when Sn-4Ag-0.5Cu and Sn-3Ag-0.5Cu solders were used as aging time increased. However, only (Cu,Ni)₆Sn₅ IMCs formed in Sn-1Ag-0.5Cu solders, when the aging time was extended beyond 1500 h. Two factors are expected to influence bond strength and fracture modes. One of the factors is that the interfacial (Ni,Cu)₃Sn₄ IMCs formed at the interface and the fact that fracture occurs along the interface. The other factor is Ag₃Sn IMCs coarsening in the solder matrix, and fracture reveals the ductility of the solder balls. The above analysis indicates that during aging, the formation of interfacial (Ni,Cu)₃Sn₄ IMCs layers strongly influences the pull strength and the fracture behavior of a solder joint. This fact demonstrates that interfacial layers are key to understanding the changes in bonding strength. Additionally, comparison of the bond strength with various Sn-Ag-Cu lead-free solders for various Ag contents show that the Sn-1Ag-0.5Cu solder joint is not sensitive to extended aging time.     

Bi对Sn-0.3Ag-0.7Cu无铅钎料熔点及润湿性能的影响

研究了添加适量的Bi元素对低银型Sn-0．3Ag-0．7Cu无铅钎料合金性能的影响,应用差示扫描量热仪和SAT-5100型润湿平衡仪对Sn-0．3Ag-0．7Cu·xBi（x=0.1,3,4．5）钎料的熔点、润湿性能作了对比试验分析。结果表明,一定量Bi元素的加入可以降低Sn-0．3Ag-0．7Cu钎料合金的熔点,并改善其润湿性能。但过多的Bi元素会导致钎料的液固相线温度差增大,塑性下降,造成焊点剥离缺陷。综合考虑得到Sn-0．3Ag-0．7Cu-3．0Bi无铅钎料具有最佳的综合性能。     

Interfacial reactions and mechanical properties between Sn-4.0Ag-0.5Cu and Sn-4.0Ag-0.5Cu-0.05Ni-0.01Ge lead-free solders with the Au/Ni/Cu substrate

Sn-4.0Ag-0.5Cu (SAC) and Sn-4.0Ag-0.5Cu-0.05Ni-0.01Ge (SACNG) lead-free solders reacting with the Au/Ni/Cu multi-layer substrate were investigated in this study. All reaction couples were reflowed at 240 and 255 °C for a few minutes and then aged at 150 °C for 100-500 h. The (Cu, Ni, Au)₆Sn₅ phase was formed by reflowing for 3 min at the interface. If the reflowing time was increased to 10 min, both (Cu, Ni, Au)₆Sn₅ and (Ni, Cu, Au)₃Sn₄ phases formed at the interface. The AuSn₄ phase was found in the solder for all reaction couples. An addition of Ni and Ge to the solder does not significantly affect the IMC formation. After a long period of heat-treatment, the thickness of the (Cu, Ni, Au)₆Sn₅ and (Ni, Cu, Au)₃Sn₄ phases increased and the intermetallic compounds (IMCs) growth mechanism obeyed the parabolic law and the IMC growth mechanism was diffusion-controlled. The mechanical strengths for both the soldered joints decreased with increasing thermal aging time. The SACNG/Au/Ni/Cu couple had better mechanical strength than that in the SAC/Au/Ni/Cu couple.     

Interfacial reactions between liquid Sn-8Zn-3Bi solders and Cu substrates

The morphology and growth kinetics of intermetallic compounds formed during the soldering reactions between Sn-8Zn-3Bi and Cu substrates at various temperatures ranging from 225 to 350 °C were investigated. The results indicated that a planar layer of Cu_32.1Zn_66.7Sn_0.7Bi_0.5 (γ phase) along with a great number of scallop-shaped intermetallic compounds Cu_19.3Zn_77.8Sn_2.9 (ɛ phase) appeared at the interfaces at temperatures lower than 325 °C. At temperatures higher than 325 °C, the interfacial intermetallics of a composition similar to the planar intermetallics appeared in cluster shape. Kinetics analysis indicated that the intermetallic growth was diffusion-controlled with activation energy of 24.6 KJ/mol.     

铜含量对Sn-Cu钎料与Cu、Ni基板钎焊界面IMC的影响

研究了不同铜含量的Sn-xCu钎料(x=0,0.1%,0.3%,0.7%,0.9%,1.5%)与Cu板和Ni板在260、280和290℃钎焊后界面金属间化合物(IMC)的成分和形貌。研究结果表明:钎料与Cu板钎焊时,钎焊温度越高,界面处形成的Cu6Sn5IMC厚度越大,而在同一钎焊温度下,随着钎料中铜含量的增加,IMC的厚度先减少后增加;与Ni板钎焊时,界面IMC的厚度随着铜含量的增加而增加,同时界面化合物的成分和形貌均发生了显著变化;当Cu含量小于0.3%(质量分数)时,界面处形成了连续的(CuxNi1-x)3Sn4层;而当Cu含量为0.7%时,界面处同时存在着短棒状(CuxNi1-x)3Sn4和大块状(CuxNi1-x)6Sn5IMC;当铜含量继续增大时(0.9%~1.5%),(CuxNi1-x)3Sn4IMC消失,只发现了棒状(CuxNi1-x)6Sn5IMC。讨论了钎料中Cu含量对与Cu、Ni基板钎焊接头界面化合物生长的影响,并进一步讨论了(CuxNi1-x)6Sn5IMC的形成和长大机理。     

Sn-30Bi-0.5Cu低温无铅钎料的微观组织及其力学性能

通过在Sn-Bi钎料中添加Cu元素制备新型Sn-30Bi-0.5Cu低温无铅钎料,对无铅钎料的力学性能及微观组织进行分析.结果表明:Cu元素的加入抑制Bi元素在钎料/铜界面处的偏析,避免形成粗大的富Bi带,并能够在钎料基体中原位生成Cu-Sn金属间化合物(Intermetallic compounds,IMC);当Cu含量约为0.5%(质量分数)时,钎料的抗拉强度和伸长率等力学性能指标最佳,并能够提高其抗振动可靠性.这主要是由于在钎料基体中原位形成的棒状或杆状IMC能有效地将脆性薄弱面钉扎和在β-Sn软相基体中形成钉轧强化,改善钎料的微观组织形态,从而提高钎焊强度和焊点的抗振动冲击可靠性,使其性能强于Sn-Bi共晶的性能而接近于Sn-Bi-Ag钎料的,Sn-30Bi-0.5Cu钎料在拉伸过程中断口存在韧性和脆性两种混合型断口.     

Thermal reliabilities of Sn-0.5Ag-0.7Cu-0.1Al2O3/Cu solder joint

The effects of trace addition of Al₂O₃ nanoparticles (NPs) on thermal reliabilities of Sn-0.5Ag-0.7Cu/Cu solder joints were investigated. Experimental results showed that trace addition of Al₂O₃ 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 Al₂O₃ NPs could slow down the shear force reduction of solder joint during thermal services, which was attributed to the pinning effect of Al₂O₃ 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 cm²/h in IA process, and from 0.92×10^-10 to 0.53×10^-10 cm²/h in TC process. This indicated that trace addition of Al₂O₃ NPs can improve both IA and TC reliabilities of Sn-0.5Ag- 0.7Cu/Cu joint, and a little more obvious in IA reliability.