Ni元素对Sn2.5Ag0.7Cu0.1RE/Cu无铅微焊点界面IMC和力学性能的影响

以Sn2.5Ag0.7Cu0.1RE无铅钎料为研究对象,借助扫描电镜和X衍射等检测方法研究了Ni元素对Sn2.5Ag0.7Cu0.1RE/Cu无铅微焊点界面IMC和力学性能的影响.结果表明,添加适量Ni元素能显著细化Sn2.5Ag0.7Cu0.1RE钎料合金初生β-Sn相和共晶组织,抑制焊点界面区(Cu,Ni)6Sn5金属间化合物的生长和表面粗糙度的增加,提高无铅焊点抗剪强度.当Ni元素添加量为0.1%时,钎料合金组织细小均匀,共晶组织所占比例较多;焊点界面IMC薄而平整,(Cu,Ni)6Sn5颗粒尺寸小,对应焊点抗剪强度最高为45.6 MPa,较未添加Ni元素焊点提高15.2%.     

超声波和电场共同作用下SnAgCuRE/Cu钎焊接头的时效特性

研究了时效对电场和超声振动共同作用下Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头组织与性能的影响。结果表明:Sn2.5Ag0.7Cu0.1RE/Cu钎焊接头界面生成的IMC主要由靠近钎料合金一侧的Cu6Sn5相,而时效后界面靠近Cu一侧出现Cu3Sn。时效过程中,随着时效时间和时效温度的增加,Sn2.5Ag0.7Cu0.1RE/Cu界面区生长受扩散机制控制,IMC总厚度增加,力学性能下降。     

苛刻热循环对Sn2.5Ag0.7Cu0.1RExNi/Cu钎焊界面及接头性能的影响

采用SEM、EDS、XRD等对苛刻热循环下Sn2.5Ag0.7Cu0.1RExNi/Cu钎焊界面IMC及接头性能进行研究。结果表明:苛刻热循环下Sn2.5Ag0.7Cu0.1RExNi/Cu钎焊界面IMC由(Cu,Ni)_6Sn_5和Cu_3Sn相组成;随热循环周期的增加,钎焊接头的界面IMC(Cu,Ni)_6Sn_5形态由波浪状转变为局部较大尺寸的"笋状",IMC平均厚度和粗糙度增大,相应接头剪切强度降低。添加适量Ni 0.05%(质量分数)的钎焊接头界面IMC平均厚度和粗糙度最低,接头剪切强度最高。在100热循环周期内,随热循环周期增加,Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头剪切断口由呈现钎缝处的韧性断裂向由钎缝和IMC层组成以韧性为主的韧-脆混合断裂转变。     

苛刻热循环对Sn2.5Ag0.7Cu0.1RExNi/Cu钎焊界面及接头性能的影响EI北大核心CSCD

采用SEM、EDS、XRD等对苛刻热循环下Sn2.5Ag0.7Cu0.1RExNi/Cu钎焊界面IMC及接头性能进行研究。结果表明:苛刻热循环下Sn2.5Ag0.7Cu0.1RExNi/Cu钎焊界面IMC由(Cu,Ni)_6Sn_5和Cu_3Sn相组成;随热循环周期的增加,钎焊接头的界面IMC(Cu,Ni)_6Sn_5形态由波浪状转变为局部较大尺寸的"笋状",IMC平均厚度和粗糙度增大,相应接头剪切强度降低。添加适量Ni 0.05%(质量分数)的钎焊接头界面IMC平均厚度和粗糙度最低,接头剪切强度最高。在100热循环周期内,随热循环周期增加,Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头剪切断口由呈现钎缝处的韧性断裂向由钎缝和IMC层组成以韧性为主的韧-脆混合断裂转变。     

SnAgCuEr系稀土无铅钎料的显微组织

系统研究了添加微量稀土Er对Sn3.8Ag0.7Cu无铅钎料合金显微组织和性能的影响.试验发现,微量Er的添加,使Sn3.8Ag0.7Cu钎料合金的熔化温度稍有降低,铺展面积有所增加,抗剪强度有所提高.通过显微组织观察,加Er后网状共晶物体积百分比增大,初晶金属间化合物(IMC)的尺寸变小.微量Er抑制了时效过程钎料与铜基体界面IMC层(IML)的增厚,时效400 h后差别更明显,有利于提高钎料接头的可靠性.指出含微量稀土的SnAgCuEr合金是性能优良的无铅钎料合金.     

时效对SnCuSb/Cu钎焊接头抗剪强度与断口特征的影响

研究了150℃时效对Sn-0.7Cu-xSb/Cu(x=0,0.25,0.5,0.75,1.0)钎焊接头抗剪强度和断口特征的影响.结果表明,随着Sb元素含量的增加,钎焊接头的抗剪强度升高;接头抗剪强度随时效时间的增加而明显降低.接头剪切断裂的位置是在钎料上,也出现在钎料和金属间化合物Cu6Sn5之间.对于焊后态试样,其断裂位置在钎料上的情况占绝大部分,断口上分布有大量韧窝,断裂类型主要是韧性断裂.随时效时间的增加,接头的断裂位置向钎料与界面化合物各占一半过渡.时效500h,断口处已经可以看到Cu3Sn的存在,断口已经由韧性转变为脆性.     

时效处理对Sn0.7Cu-0.5Al_2O_3/Cu焊点界面形态的影响

研究了纳米Al_2O_3颗粒对Sn0.7Cu钎料润湿性的影响,并分析比较了时效0 h和时效250 h后Sn0.7Cu-0.5Al_2O_3/Cu焊点界面IMC的形貌和厚度变化。结果表明:添加微量的纳米Al_2O_3颗粒可以改善Sn0.7Cu钎料的润湿性,但添加过量将降低润湿铺展面积,纳米Al_2O_3颗粒的最佳添加量为0.5%,比Sn0.7Cu钎料的铺展面积提高了30.2%。焊后未时效的焊点钎料晶粒细小,界面处Cu_6Sn_5IMC层较薄,经过150℃时效,钎料晶粒粗化,IMC界面层的厚度明显增加,形貌由扇贝状变为明显的块状,界面的不平度逐步减小。界面层由单一的Cu_6Sn_5IMC层转变为Cu_6Sn_5IMC和Cn_3SnIMC两层,厚度增大了96.5%。     

Ni改性GNSs对SnAgCuRE/Cu钎焊接头热老化特性的影响

以Sn2.5Ag0.7Cu0.1RE0.05Ni无铅钎料合金为研究对象,基于石墨烯纳米片（GNS）独特的结构、优异的物理性能和力学性能,以其为复合钎料的增强相,开展基于Ni改性GNSs（Ni-GNSs）增强SnAgCuRE系复合钎料/Cu的钎焊和钎焊接头热老化试验,探讨Ni-GNSs对复合钎料组织及钎焊接头热老化失效断裂机制的影响。结果表明：Ni-GNSs的加入,抑制了复合钎料的线膨胀,产生晶格畸变,导致位错产生,金属间化合物（IMC）颗粒分布在位错线附近,与位错发生交互作用,阻碍位错运动,强化复合钎料,进而强化复合钎料接头。随着热老化时间延长,钎焊接头界面IMC层厚度增加,剪切强度降低;其中,添加0.05%（质量分数）GNSs的复合钎料接头剪切强度降幅最小,为8.9%,且热老化384 h后,其剪切强度仍高于Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu合金接头热老化前的剪切强度。Ni-GNSs的加入,使复合钎料钎焊接头界面IMC的生长系数明显降低,有效缓解了复合钎料/Cu钎焊接头热老化过程中力学性能的降低,进而改变复合钎料/Cu钎焊接头的热老化失效断裂机制,最终影响接头的可靠性。Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头的断裂位置由热老化前的钎缝区向钎缝/界面IMC移动,变为韧脆混合断裂;而添加0.05%（质量分数）GNSs复合钎料接头的断裂位置均在钎缝区,为韧性断裂,钎焊接头可靠性较高。     

石墨/紫铜间接钎焊接头的界面组织及力学性能

在950℃,30 min条件下,采用含活性元素Ti的Sn0.3Ag0.7Cu-x Ti(x=1.0,1.2,1.4,1.6,1.8,质量分数,%)金属粉末对石墨进行反应金属化,然后用Sn0.3Ag0.7Cu钎料在真空条件下实现了紫铜和石墨的间接钎焊.钎焊接头的典型界面结构为:紫铜/Cu3Sn/Cu6Sn5/b-Sn/Ti C/石墨.在反应金属化过程中金属化粉末中的Ti起到重要作用,而Ti含量对钎焊接头的界面组织和抗剪强度没有影响.随着钎焊温度升高,紫铜中越来越多的Cu溶解到液相钎料中反应生成Cu-Sn化合物,接头的抗剪强度有一定程度的提高.断口分析表明:接头主要在b-Sn层中断裂,并呈现韧性断裂.当Cu-Sn化合物充满整个钎缝(600℃),接头强度大幅提高,达到30 MPa,接头在石墨母材完全断裂.     

外能辅助下Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头组织与性能

采用SEM、EDS、XRD等方法研究了超声、电场外能辅助下Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头的组织与性能。结果表明,借助于超声、超声-电场外能辅助能细化Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头钎缝组织并使共晶组织比例增加,界面区金属间化合物(IMC)平均厚度、粗糙度和界面IMC颗粒尺寸减小。超声和电场外能辅助下Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头强度与其界面IMC层粗糙度密切相关,超声的作用更为显著,在超声-电场外能辅助钎焊接头界面IMC层粗糙度降低中占主导作用,施加超声-电场外能辅助下钎焊接头剪切强度与传统钎焊相比提高24.1%;施加超声、超声-电场外能辅助使Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头断裂途径由钎缝和界面IMC层组成的界面过渡区向钎缝侧迁移,呈界面(Cu,Ni)_6Sn_5 IMC解理和钎缝解理+韧窝的脆-韧混合型断裂机制,使接头剪切断口塑性区比例增加,从而提高接头剪切强度。     

RE对Sn2.5Ag0.7Cu/Cu焊点性能的影响

利用X射线衍射分析仪(XRD)和JSM-5610LV扫描电镜(SEM)研究RE含量对Sn2.5Ag0.7Cu/Cu焊点界面区显微组织、剪切强度和蠕变断裂寿命的影响。结果表明:Sn2.5Ag0.7CuxRE焊点界面区金属间化合物由靠近钎料侧Cu6Sn5和靠近Cu基板侧Cu3Sn构成;添加微量RE可细化Sn2.5Ag0.7Cu焊点内钎料合金的显微组织和改善钎焊接头界面区金属间化合物的几何尺寸及形态;当RE添加量为0.1%时,焊点的剪切强度最高,蠕变断裂寿命最长。     

Influence of Cu Nanoparticles on Microstructure and Mechanical Properties of Sn0.7Ag0.5Cu-BiNi/Cu Solder Joint

The influence of Cu nanoparticles addition on microstructure and mechanical properties of Sn0.7Ag0.5Cu-BiNi/Cu solder joint after reflow and isothermal aging has been investigated in this study. Experimental results indicate that the addition of Cu nanoparticles suppresses the growth of intermetallic compound (IMC) layer at the interface after reflow and aging. Moreover, the bulk solder appears with refined microstructure after adding Cu nanoparticles. In addition, solder joints containing Cu nanoparticles display higher microhardness due to the dispersive distribution of Cu nanoparticles as well as the refined IMC particles. The addition of 0.1% Cu nanoparticles can improve the microhardness by 16% compared with the noncomposite. However, the existing porosity in the solder exerts a negative effect on microhardness and shear strength. The mechanism of porosity formation has been discussed in detail. Porosity increases markedly with increasing Cu nanoparticles proportion.     

Reliability studies of Sn–9Zn/Cu solder joints with aging treatment

Sn–9Zn (in wt.%) solder ball was bonded to Cu pad, and the effect of aging on shear reliability was investigated. After reflow, the intermetallic compound (IMC) phase formed at the interface was Cu₅Zn₈, and the as-reflowed Sn–9Zn/Cu joint had sufficient shear strength. In the isothermal aging test, only Cu₅Zn₈ IMC was observed in the samples aged at temperatures between 70 and 120 °C. On the other hand, after aging at 150 °C for 250 h, Cu₆Sn₅ phase was observed at the interface between the interfacial Cu₅Zn₈ IMC layer and the Cu substrate. And, the layer-type Cu₅Zn₈ IMC layer was disrupted locally at the interface. In the ball shear test conducted after aging treatment, the shear strength significantly decreased after aging at all temperatures for initial 100 h, and then remained constant by further prolonged aging. The fracture mainly occurred at the interface between the solder and Cu₅Zn₈ IMC layer. The aged Sn–9Zn/Cu solder joint had an inferior joint reliability.     

Sn5Sb1Cu0.1Ni0.1Ag/Cu(Ni)焊点的抗时效性能

采用扫描电镜(SEM)研究在150 ℃等温时效下Cu/Sn5Sb1Cu0.1Ni0.1Ag/Cu与Ni/Sn5Sb1Cu0.1Ni0.1Ag/Ni焊点的界面扩散行为. 结果表明,在时效过程中,随着时效时间的增加,Cu/Sn5Sb1Cu0.1Ni0.1Ag/Cu焊点界面金属间化合物(intermetallic compound,IMC)形貌由开始的细针状生长为棒状,IMC层厚度增加,界面IMC主要成分为(Cu,Ni)₆Sn₅. Ni/Sn5Sb1Cu0.1Ni0.1Ag/Ni焊点的界面IMC形貌由细小突起状转变为较为密集颗粒状,且IMC层厚度增加,界面IMC主要成分为(Cu,Ni)₃Sn₄. 经过线性拟合,两种焊点的界面IMC层生长厚度与时效时间t1/2呈线性关系,Sn5Sb1Cu0.1Ni0.1Ag/Cu界面间IMC的生长速率为7.39 × 10?2 μm2/h,Sn5Sb1Cu0.1Ni0.1Ag/Ni界面间IMC的生长速率为2.06 × 10?2 μm2/h. 镀镍层的加入可以显著改变界面IMC的形貌,也可降低界面IMC的生长速率,抑制界面IMC的生长,显著提高抗时效性能.     

Enhancement of the wettability and solder joint reliability at the Sn–9Zn–0.5Ag lead-free solder alloy–Cu interface by Ag precoating

The enhancement of the wettability and solder joint reliability at the Sn–9Zn–0.5Ag solder alloy–Cu interface by Ag precoating has been investigated. The wettability of the Sn–9Zn–0.5Ag solder alloy–Cu interface has been improved by Ag precoating. The adhesion strength of the solder alloy–Ag precoated Cu interface increases from 4.11±0.56 to 6.92±0.85 MPa as dipped at 250 °C for 10 s. When the dipping time is prolonged from 10 to 30 s, the interfacial adhesion strength increases from 6.92±0.85 to 13.62±0.73 MPa. The interfacial adhesion strength is enhanced by the rod-like Cu–Zn intermetallic compound (IMC) formed close to the interface. The diffusion coefficients of Sn and Zn in the IMC layer are determined as 5.76×10⁻¹⁰ and 9.50×10⁻¹¹ cm²/s at the Sn–9Zn–0.5Ag–Cu and Sn–9Zn–0.5Ag–Ag precoated Cu interfaces, respectively.     

Sn-6.5Zn/Cu焊点时效过程中的界面特征与结构演变

研究150°C等温时效对Sn-6.5Zn/Cu焊点微观结构特征与显微硬度的影响,分析界面金属间化合物的形成与演变机制。结果表明：Sn-6.5Zn/Cu焊点界面化合物层由CuZn和Cu5Zn8组成;随着等温时效时间的延长,化合物层的厚度表现为先增大、后减小的趋势;长时间的高温时效会导致Cu-Zn金属间化合物的分解,并破坏界面连续致密的化合物层。在局部破坏的界面区Cu基体处形成不连续的Cu6Sn5化合物层;时效后界面粗化并形成明显的孔洞。时效导致界面显微硬度不同程度的增大。     

Investigation of small Sn–3.5Ag–0.5Cu additions on the microstructure and properties of Sn–8Zn–3Bi solder on Au/Ni/Cu pads

The formation of intermetallic compounds and the shear strength of Sn–Zn–Bi solder alloys with various (0, 1, 3, 5 and 7 wt%) weight percentages of Sn–Ag–Cu were investigated on Au/Ni metallized Cu pads depending on the number of reflow cycles. In Sn–Zn–Bi solder joints, scallop-shaped AuZn₃ intermetallic compound (IMC) particles were found at the interfaces and in the solder ball regions, fine Bi- and needle-shaped Zn-rich phase were observed in the Sn matrix. After Sn–Ag–Cu additions, an additional Ag–Zn intermetallic compound layer was adhered to the top surface of the AuZn₃ layer at the interface and fine spherical-shaped AgZn₃ intermetallic compound particles were detected in the solder ball regions together with Bi- and Zn-rich phase volumes. After the addition of Sn–Ag–Cu, the shear strength of Sn–Zn–Bi solder joints increased due to the formation of the fine AgZn₃ intermetallic compound particles. The shear strengths of Sn–Zn–Bi and Sn–Zn–Bi/7 wt% Sn–Ag–Cu solder joints after one reflow cycle were about 44.5 and 53.1 MPa, respectively and their shear strengths after eight reflow cycles were about 43.4 and 51.6 MPa, respectively.     

时效时间对Cu/In-Sn-2.5Ag/Cu焊点组织形貌及剪切性能的影响

研究了Cu/In-Sn-2.5Ag/Cu复合钎料焊点在125 ℃时效不同时间后的微观组织和剪切性能。结果表明:随着时效时间的延长,Cu/In-Sn-2.5Ag/Cu焊点界面金属间化合物(IMCs)层厚度呈现增加的趋势,焊点界面IMCs层组织先生成Cu₆(In, Sn)₅相,同时焊点中生成少量的Ag₉In₄相,随着时效时间的延长,钎料与Cu原子进一步反应生成Cu₃(In, Sn),部分Ag₉In₄转变为Ag₃In。当时效时间为168 h,形成全IMCs焊点。焊点剪切强度随时效时间延长呈现先增大后减小的趋势,时效时间为120 h时剪切强度最大,达到15.38 MPa。