Although there are many lead-free soldering alloys on the market, none of them have ideal qualities. The researchers are combining binary alloys with a variety of additional materials to create the soldering alloys’ ...Although there are many lead-free soldering alloys on the market, none of them have ideal qualities. The researchers are combining binary alloys with a variety of additional materials to create the soldering alloys’ features. The eutectic Sn-9Zn alloy is among them. This paper investigated the mechanical and electrical properties of Sn-9Zn-x (Ag, Cu, Sb);{x = 0.2, 0.4, and 0.6} lead-free solder alloys. The mechanical properties such as elastic modulus, ultimate tensile strength (UTS), yield strength (YS), and ductility were examined at the strain rates in a range from 4.17 10−3 s−1 to 208.5 10−3 s−1 at room temperature. It is found that increasing the content of the alloying elements and strain rate increases the elastic modulus, ultimate tensile strength, and yield strength while the ductility decreases. The electrical conductivity of the alloys is found to be a little smaller than that of the Sn-9Zn eutectic alloy.展开更多
The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carrie...The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carried out at room temperature at the strain rate of 4.17 × 10<sup>-3</sup> s<sup>-1</sup>, 20.85 × 10<sup>-3</sup> s<sup>-1</sup>, and 208.5 × 10<sup>-3</sup> s<sup>-1</sup>. It is seen that the tensile strength increases and the ductility decrease with increasing the strain rate over the investigated range. From the strain rate change test results, the strain sensitivity values are found in the range of 0.0831 to 0.1455 due to the addition of different alloying elements.展开更多
Soldering experiments with Sn-3.5Ag-0.5Cu lead-free solder on Au/Ni/Cu pad were carried out by means of diode-laser and IR reflow soldering methods respectively.The influence of different heating methods as well as ou...Soldering experiments with Sn-3.5Ag-0.5Cu lead-free solder on Au/Ni/Cu pad were carried out by means of diode-laser and IR reflow soldering methods respectively.The influence of different heating methods as well as output power of diode-laser on shear force of micro-joints was studied and the relationship between the shear force and microstructures of micro-joints was analyzed.The results indicate that the formation of intermetallic compound Ag3Sn is the key factor to affect the shear force and the fine eutectic network structures of micro-joints as well as the dispersion morphology of fine compound Ag3Sn,in which eutectic network band is responsible for the improvement of the shear force of micro-joints soldered with Sn-Ag-Cu lead-free solder.With the increases of output power of diode-laser,the shear force and the microstructures change obviously.The eutectic network structures of micro-joints soldered with diode-laser soldering method are more homogeneous and the grains of Ag3Sn compounds are finer in the range of near optimal output power than those soldered with IR reflow soldering method,so the shear force is also higher than that using IR reflow soldering method.When the output power value of diode-laser is about 41.0 W,the shear force exhibits the highest value that is 70% higher than that using IR reflow soldering method.展开更多
This article explores tile effects of phosphorus addition on the wettability between Sn-9Zn solder alloy and Cu substrates, the oxidation behavior and the corrosion behavior of Sn-9Zn solder alloy. Spreading test was ...This article explores tile effects of phosphorus addition on the wettability between Sn-9Zn solder alloy and Cu substrates, the oxidation behavior and the corrosion behavior of Sn-9Zn solder alloy. Spreading test was used to characterize the wettability of Sn-9Zn-xP solder alloys to Cu substrates. The oxidation and corrosion behaviors of Sn- 9Zn-xP solder alloys were determined by means of weight gaining, and secondary ion mass spectrometry was used to analyze the oxygen content. The role and mechanism of P in the solder alloys were also discussed. It is found that the addition of P can significantly improve the wettability of the solder alloys. Incorporating P into Sn-9Zn solder alloy obviously decreases the oxygen content and enhances the oxidation and corrosion resistance. Microstructure observations show that an appropriate amount of P can greatly refine coarse rod-like Zn-rich phases in Sn-gZn solder alloy.展开更多
The effects of Ag on the microstructure and corrosion behavior of pre-soldering Sn-xAg lead-free solders,and on the formation of intermetallic layer of the solders with Cu substrate were investigated.The Ag contents(x...The effects of Ag on the microstructure and corrosion behavior of pre-soldering Sn-xAg lead-free solders,and on the formation of intermetallic layer of the solders with Cu substrate were investigated.The Ag contents(x)were 0,3.0,3.5,4.0,and5.0 wt.%.The Ag content played a role in the morphology of Ag3 Sn phase in the solders.The microstructure analysis showed that theβ-Sn phase was surrounded by eutectic networks in the 3.0 Ag and 3.5 Ag solders and large plate-like Ag3 Sn formed in the 4.0 Ag and5.0 Ag solders.Nonetheless,the Ag content slightly impacted the corrosion behavior of the as-cast solders as characterized using potentiodynamic polarization test.After soldering,only a single layer of a Cu6 Sn5 intermetallic compound formed at the Sn-xAg/Cu interface.By comparison,the Cu6 Sn5 intermetallic layer of the Ag-doped solders was thinner than that of the 0Ag solder.The fine Ag3 Sn particles in the eutectic networks precipitating in the 3.0 Ag and 3.5 Ag solders effectively hindered the growth of Cu6 Sn5 grains compared to large plate-like Ag3 Sn in the 4.0 and 5.0Ag solders.展开更多
Sn-Ag alloy system has been regarded as one of the most promising lead-free solder to substitute conventional Sn- Pb eutectic solder. But the formation of bulk Ag3Sn intermetallic compounds （IMCs） during reflow and ...Sn-Ag alloy system has been regarded as one of the most promising lead-free solder to substitute conventional Sn- Pb eutectic solder. But the formation of bulk Ag3Sn intermetallic compounds （IMCs） during reflow and post heat treatment significantly influences the performance of the solder joints. With an effort to clarify its microstructural evolution as a function of slow cooling rates, the fraction of bulk IMCs within the slowly solidified Sn-4.0 wt pct Ag solder was investigated by standard metallographic and compared with that detected by thermal analysis. It was found that the bulk IMCs fraction determined by thermal analysis corresponds quite well with the microstructure observation results. In accordance with the conventional solidification theory, the lower the applied cooling rate, the fewer the amount of bulk Ag3Sn IMCs formed in Sn-4.0 wt pct Ag alloy. In addition, Vickers hardness measurement results indicated that the relative coarse eutectic Ag3Sn IMCs distributing in the lamellar eutectic structure favored the improvement of the mechanical performance.展开更多
An orthogonal method was used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the wetting characteristics of Sn-9Zn lead-free solders by wetting balance method. The results show that the optimal loadi...An orthogonal method was used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the wetting characteristics of Sn-9Zn lead-free solders by wetting balance method. The results show that the optimal loading of Ga, Al, Ag, and Ce was 0.2 wt.%, 0.002 wt.%, 0.25 wt.%, and 0.15 wt.%, respectively. Intermetallic compounds （IMCs） formed at the interface between Sn-9Zn-0.2Ga-0.002Al-0.25Ag- 0.15Ce solder and Cu substrate were investigated by scanning electron microscope （SEM） and energy dispersive spectroscopy （EDS） analysis. The SEM images illustrate that the IMCs can be divided into two portions from the substrate side to the solder side： a planar CusZns layer and an additional continuous scallop-like AgZn3 layer. The EDS analysis also shows that Ga segregates in the solder abutting upon the interface. X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES） of the surface components of Sn-9Zn-0.2Ga-0.002Al- 0.25Ag-0.15Ce solder indicate that Al aggregates at the surface in the form of Al203 protective fdm, which prevents the further oxidation of the solder surface. On the other hand, Ce aggregates at the subsurface, which may reduce the surface tension of the solder and improve the wettability in consequence.展开更多
The Sn-Cu-Ni-Ge solder is a strong challenger to the Sn-Ag-Cu（SAC） solders as a replacement for the Sn-Pb eutectic solder. This research investigated the effects of addition of Ag, Bi, In, and Sb on the physical pro...The Sn-Cu-Ni-Ge solder is a strong challenger to the Sn-Ag-Cu（SAC） solders as a replacement for the Sn-Pb eutectic solder. This research investigated the effects of addition of Ag, Bi, In, and Sb on the physical properties of the Sn-0.6 Cu-0.05 Ni-Ge（SCNG） lead-free solder and the interfacial reaction with the Cu substrate. The melting behavior, microstructure, tensile strength, and wettability of the SCNG-x（x=Ag, Bi, In, Sb） solders were examined. The findings revealed that the introduction of Ag, Bi, In, and Sb minimally altered the solidus temperature, liquidus temperature, and tensile strength of the solder. However, the cooling behavior and solidified microstructure of the solder were affected by the concentration of the alloying elements. The wettability of the SCNG solder was improved with the doping of the alloying elements except Sb. The thickness of intermetallic layer was increased by the addition of the alloying elements and was related to the cooling behavior of the solder. The morphology of intermetallic layer between the SCNG-x solders and the Cu substrate was different from that of the typical SAC solders. In conclusion, alloying the SCNG solder with Ag, Bi, In or Sb is able to improve particular properties of the solder.展开更多
The effect of Cu content on the microstructure,grain orientation and mechanical properties of Sn-xCu(x=0-4.0 wt.%)lead-free solder was studied.Results showed that added Cu induced the formation of intermetallic phases...The effect of Cu content on the microstructure,grain orientation and mechanical properties of Sn-xCu(x=0-4.0 wt.%)lead-free solder was studied.Results showed that added Cu induced the formation of intermetallic phases.Only theη-Cu;Sn;andε-Cu;Sn phases were present in theβ-Sn matrix.For all contents,the strongly preferred orientation of theβ-Sn phase was formed on the{001}plane.In Sn doped with 1.0 wt.%Cu,theη-Cu;Sn;phase exhibited the preferred orientation of{0001}plane,whereas doping with 3.0 or 4.0 wt.%Cu transformed the preferred orientation to the{010}plane.In addition,only the{0001}and{■}planes were present in theε-Cu;Sn phase.The high Cu contents contributed to an increased number of low-angle boundaries,high residual strain,tensile strength and microhardness.展开更多
A lead-free Sn-3.5Ag solder was prepared by rapid solidification technology. The high solidification rate, obtained by rapid cooling, promotes nucleation, and suppresses the growth of Ag3Sn intermetallic compounds （I...A lead-free Sn-3.5Ag solder was prepared by rapid solidification technology. The high solidification rate, obtained by rapid cooling, promotes nucleation, and suppresses the growth of Ag3Sn intermetallic compounds （IMCs） in Ag-rich zone, yielding fine Ag3Sn nanoparticulates with spherical morphology in the matrix of the solder. The large amount of tough homogeneously-dispersed IMCs helps to improve the surface area per unit volume and obstructs the dislocation lines passing through the solder, which fits with the dispersion-strengthening theory. Hence, the rapidly-solidified Sn-3.5Ag solder exhibits a higher rnicrohardness when compared with a slowly-solidified Sn-3.5Ag solder.展开更多
The influence of Mo and ZrO_(2)nanoparticles addition on the interfacial properties and shear strength of Sn58Bi solder joint was investigated.The interfacial microstructures of Sn58Bi/Cu,Sn58Bi+Mo/Cu and Sn58Bi+ZrO_(...The influence of Mo and ZrO_(2)nanoparticles addition on the interfacial properties and shear strength of Sn58Bi solder joint was investigated.The interfacial microstructures of Sn58Bi/Cu,Sn58Bi+Mo/Cu and Sn58Bi+ZrO_(2)/Cu solder joints were analysed using a scanning electron microscope(SEM)coupled with energy dispersive X-ray(EDX)and the X-ray diffraction(XRD).Intermetallic compounds(IMCs)of MoSn_(2)are detected in the Sn58Bi+Mo/Cu solder joint,while SnZr,Zr_(5)Sn_(3),ZrCu and ZrSn_(2)are detected in Sn58Bi+ZrO_(2)/Cu solder joint.IMC layers for both composite solders comprise of Cu_(6)Sn_(5) and Cu_(3)Sn.The SEM images of these layers were used to measure the IMC layer’s thickness.The average IMC layer’s thickness is 1.4431μm for Sn58Bi+Mo/Cu and 0.9112μm for Sn58Bi+ZrO_(2)/Cu solder joints.Shear strength of the solder joints was investigated via the single shear lap test method.The average maximum load and shear stress of the Sn58Bi+Mo/Cu and Sn58Bi+ZrO_(2)/Cu solder joints are increased by 33%and 69%,respectively,as compared to those of the Sn58Bi/Cu solder joint.By comparing both composite solder joints,the latter prevails better as adding smaller sized ZrO_(2)nanoparticles improves the interfacial properties granting a stronger solder joint.展开更多
The eutectic Sn-9Zn alloy was doped with Ag （0 wt.%-1 wt.%） to form Sn-9Zn-xAg lead-free solder alloys. The effect of the addition of Ag on the microstructure and solderability of this alloy was investigated and int...The eutectic Sn-9Zn alloy was doped with Ag （0 wt.%-1 wt.%） to form Sn-9Zn-xAg lead-free solder alloys. The effect of the addition of Ag on the microstructure and solderability of this alloy was investigated and intermetallic compounds （IMCs） formed at the solder/Cu interface were also examined in this study. The results show that, due to the addition of Ag, the microstructure of the solder changes. When the quantity of Ag is lower than 0.3 wt.%, the needle-like Zn-rich phase decreases gradually. However, when the quantity of Ag is 0.5 wt.%-1 wt.%, Ag-Zn intermetallic compounds appear in the solder. In particular, adding 0.3 wt.% Ag improves the wetting behavior due to the better oxidation resistance of the Sn-9Zn solder. The addition of an excessive amount of Ag will deteriorate the wetting property because the gluti- nosity and fluidity of Sn-9Zn-（0.5, 1）Ag solder decrease. The results also indicate that the addition of Ag to the Sn-Zn solder leads to the precipitation of ε-AgZn3 from the liquid solder on preformed interracial intermetallics （CusZn8）. The peripheral AgZn3, nodular on the Cu5Zn8 IMCs layer, is likely to be generated by a peritectic reaction L ＋ γ-Ag5Zns→AgZn3 and the following crystallization of AgZn3.展开更多
Effect of different contents of La and Ga on the wettability and the mierostrueture of interface of Sn-8.9Zn- 2.7Bi trinary alloys was studied. The results show that different contents of La and Ga have significant ef...Effect of different contents of La and Ga on the wettability and the mierostrueture of interface of Sn-8.9Zn- 2.7Bi trinary alloys was studied. The results show that different contents of La and Ga have significant effect on the wettability of Sn-Zn-Bi based lead-free solder under the condition of both atmosphere and nitrogen. By adding suitable amount of Ga, Cu and La to Sn-Zn-Bi solder, a new lead-free solder Sn-8.9Zn-2.7Bi- 1.0Ga-0.5Cu-0.2La with better wettability was prepared, which has a wetting angle of 25.1° to Cu.展开更多
The microstructure and melting behavior of Sn-9Zn-2Cu （SZC） lead-free solder with 3 wt pct Bi and various amount of Ni additions were studied. The wetting properties and the interracial reaction of Sn-Zn-Cu with Cu ...The microstructure and melting behavior of Sn-9Zn-2Cu （SZC） lead-free solder with 3 wt pct Bi and various amount of Ni additions were studied. The wetting properties and the interracial reaction of Sn-Zn-Cu with Cu substrate were also examined. The results indicated that the addition of 3 wt pct Bi could decrease the melting point of the solder and Ni would refine the microstructure and the rod-shape Cu5Zn8 phase changed into square-shape （Cu, Ni）5Zn8 phase. The addition of Bi, Ni greatly improved the wettability of SZC solder. In addition, the interracial phase of the solders/Cu joint was typical planar Cu5Zn8 in SZC-3Bi-INi alloy.展开更多
In the present work, the effect of Ni doping on the microstructures and properties of Zn-20 Sn high temperature lead-free solder has been investigated. Interestingly,Ni was present as the form of Ni-Zn compounds in th...In the present work, the effect of Ni doping on the microstructures and properties of Zn-20 Sn high temperature lead-free solder has been investigated. Interestingly,Ni was present as the form of Ni-Zn compounds in the microstructure of Zn-20 Sn-xNi alloy.When the Ni-doping amount was 0.2~0.4 wt.%, the presence of δ phase was found, and when the doping amoun was 0.8 wt.%, the presence of γ phase was observed. With the increase of Ni content, the liquidus temperature increased but the solidus temperature did not change obviously. In addition, the microhardness and electrical resistivities of Zn-20 Sn-xNi solder increased gradually. And the spreading area and shear strength increased firstly but decreased afterwards. When the content of Ni was 0.4 wt.%, the spreading area and shear strength of solder reached to be maximum. After the addition of 0.4 wt.% Ni, the microstructure of the interfacial intermetallic compound(IMC) layer of the interface didn't change, but the total thickness of the IMC layer reduced. The δ-phase was embedded in the grain boundary of ε-Cu Zn5, which hindered the diffusion of atoms. The thickness of IMC layer at the interface reduced, which led to the improvement of the shear strength of the interface.展开更多
An experimental study on the microstructures of a rapid directionally solidified metallo-eutectic Sn-Cu alloy was carried out. This material is an important alloy that is used as a lead-free solder. The results showed...An experimental study on the microstructures of a rapid directionally solidified metallo-eutectic Sn-Cu alloy was carried out. This material is an important alloy that is used as a lead-free solder. The results showed that the kinetic undercooling due to the rapid solidification process led to the formation of a pseudoeutectic zone, whereas the hypereutectic reaction produced the regular lamellar structure in the hypereutectic Sn-1.0Cu alloy. The corresponding arm spacing in the obtained lamellar phases decreased gradually with the increase of the applied cooling rate, which corresponded well with the prediction of a rapid directional solidification model.展开更多
The Sn-9Zn lead-free solder alloy was prepared by conventional casting technique then cold-rolled into long sheets of 1 mm thickness and 3 mm width. It was annealed at 80, 120 and 160°C for 60 min to investigate ...The Sn-9Zn lead-free solder alloy was prepared by conventional casting technique then cold-rolled into long sheets of 1 mm thickness and 3 mm width. It was annealed at 80, 120 and 160°C for 60 min to investigate the effect of isochronal heat treatment on structure and mechanical properties of the cold rolled Sn-9Zn alloy. The results showed that, the crystallite size and lattice strain have opposite behavior with increasing annealing temperature due to recovery and recrystalization processes associated with the heat treatment process. Vickers micro-hardness number increases continuously from 155 to 180 MPa with increasing annealing temperature. Ultimate tensile strength (UTS) was also calculated. It was found that, it is equal to 61.4 MPa for the non annealed sample and slightly decreases to 60.5 and 58.2 MPa for samples annealed at 80 and 120°C, respectively. While, increases to 65.4 MPa for the sample annealed at 160°C. Also, ductility increases with increasing annealing temperature in opposite manor with the UTS. The new method for Micro-creep behavior as well as the creep rate calculated by this method has been characterized at room temperature.展开更多
Emf technique was employed to determine indium activities in the liquid Ag-In-Pd alloys using galvanic cells with yttria-stabilised-zirconia as solid electrolyte according to the scheme： kanthal/rhenium, Ag-In-Pd, In...Emf technique was employed to determine indium activities in the liquid Ag-In-Pd alloys using galvanic cells with yttria-stabilised-zirconia as solid electrolyte according to the scheme： kanthal/rhenium, Ag-In-Pd, In2O3 ｜ YSZ ｜ Ni, NiO, Pt. Composition and temperature measurement ranges were limited, because of very steep liquidus surface; 35 compositions for Xpd up to 0.3 were investigated and at temperatures from near-liquidus up to 1700 K. High temperature experiments required special moly furnace to be constructed with unique automatic gas supply system for fumace winding protective atmosphere. Emf readings were taken and recorded by automatic data acquisition system. Linear dependence of emf on temperature was observed for all compositions investigated, and results were approximated by straight line equa- tions. Then In activities were calculated using well-known relations and taking into account correction for thermoelectric power between kanthal and platinum. Results are to be used along with other existing data to perform assessment of the ternary system under accord.展开更多
Conventional planar flow casting(PFC) is one of rapid solidification processes for the fabrication of microcrystalline or amorphous ribbons.Based on the conventional PFC process,the planar flow casting atomization(PFC...Conventional planar flow casting(PFC) is one of rapid solidification processes for the fabrication of microcrystalline or amorphous ribbons.Based on the conventional PFC process,the planar flow casting atomization(PFCA) process has been developed,which is a new rapid solidification process for the production of metal powder directly from alloy melts.A prototype experimental apparatus was designed and manufactured.With the apparatus,Sn60Pb40 alloy solder powders were prepared,and the effects of the main technological parameters on the powder size distribution and morphology were experimentally studied.The experimental investigations indicate that the metal powders produced by the PFCA process can be classified by velocity;and fine spherical tin-lead alloy solder powders can be fabricated by adjusting the technical parameters.The new PFCA process has such features as high productivity and efficiency,low energy consumption,simple operation,short technological process,and large gross yield.展开更多
The effect of Sb content on the properties of Sn-Bi solders was studied. The nonequilibrium melting behaviors of a series of Sn-Bi-Sb solders were examined by differential scanning calorimetry （DSC）. The spreading t...The effect of Sb content on the properties of Sn-Bi solders was studied. The nonequilibrium melting behaviors of a series of Sn-Bi-Sb solders were examined by differential scanning calorimetry （DSC）. The spreading test was carried out to characterize the wettability of Sn-Bi-Sb solders on Cu substrate. The mechanical properties of the solders/Cu joints were evaluated. The results show that the ternary alloy solders contain eutectic structure resulting from quasi-peritetic reaction. With the increase of Sb content, the amount of the eutectic structure increases. At a heating rate of 5 ℃/min, Sn-Bi-Sb alloys exhibit a higher melting point and a wider melting range. A small amount of Sb has an impact on the wettability of Sn-Bi solders. The reaction layers form during spreading process. Sb is detected in the reaction layer while Bi is not detected. The total thickness of reaction layer between solder and Cu increases with the increase of the Sb content. The shear strength of the Sn-Bi-Sb solders increases as the Sb content increases.展开更多
文摘Although there are many lead-free soldering alloys on the market, none of them have ideal qualities. The researchers are combining binary alloys with a variety of additional materials to create the soldering alloys’ features. The eutectic Sn-9Zn alloy is among them. This paper investigated the mechanical and electrical properties of Sn-9Zn-x (Ag, Cu, Sb);{x = 0.2, 0.4, and 0.6} lead-free solder alloys. The mechanical properties such as elastic modulus, ultimate tensile strength (UTS), yield strength (YS), and ductility were examined at the strain rates in a range from 4.17 10−3 s−1 to 208.5 10−3 s−1 at room temperature. It is found that increasing the content of the alloying elements and strain rate increases the elastic modulus, ultimate tensile strength, and yield strength while the ductility decreases. The electrical conductivity of the alloys is found to be a little smaller than that of the Sn-9Zn eutectic alloy.
文摘The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carried out at room temperature at the strain rate of 4.17 × 10<sup>-3</sup> s<sup>-1</sup>, 20.85 × 10<sup>-3</sup> s<sup>-1</sup>, and 208.5 × 10<sup>-3</sup> s<sup>-1</sup>. It is seen that the tensile strength increases and the ductility decrease with increasing the strain rate over the investigated range. From the strain rate change test results, the strain sensitivity values are found in the range of 0.0831 to 0.1455 due to the addition of different alloying elements.
文摘Soldering experiments with Sn-3.5Ag-0.5Cu lead-free solder on Au/Ni/Cu pad were carried out by means of diode-laser and IR reflow soldering methods respectively.The influence of different heating methods as well as output power of diode-laser on shear force of micro-joints was studied and the relationship between the shear force and microstructures of micro-joints was analyzed.The results indicate that the formation of intermetallic compound Ag3Sn is the key factor to affect the shear force and the fine eutectic network structures of micro-joints as well as the dispersion morphology of fine compound Ag3Sn,in which eutectic network band is responsible for the improvement of the shear force of micro-joints soldered with Sn-Ag-Cu lead-free solder.With the increases of output power of diode-laser,the shear force and the microstructures change obviously.The eutectic network structures of micro-joints soldered with diode-laser soldering method are more homogeneous and the grains of Ag3Sn compounds are finer in the range of near optimal output power than those soldered with IR reflow soldering method,so the shear force is also higher than that using IR reflow soldering method.When the output power value of diode-laser is about 41.0 W,the shear force exhibits the highest value that is 70% higher than that using IR reflow soldering method.
基金supported by the National Natural Science Foundation of China(No.50904035)
文摘This article explores tile effects of phosphorus addition on the wettability between Sn-9Zn solder alloy and Cu substrates, the oxidation behavior and the corrosion behavior of Sn-9Zn solder alloy. Spreading test was used to characterize the wettability of Sn-9Zn-xP solder alloys to Cu substrates. The oxidation and corrosion behaviors of Sn- 9Zn-xP solder alloys were determined by means of weight gaining, and secondary ion mass spectrometry was used to analyze the oxygen content. The role and mechanism of P in the solder alloys were also discussed. It is found that the addition of P can significantly improve the wettability of the solder alloys. Incorporating P into Sn-9Zn solder alloy obviously decreases the oxygen content and enhances the oxidation and corrosion resistance. Microstructure observations show that an appropriate amount of P can greatly refine coarse rod-like Zn-rich phases in Sn-gZn solder alloy.
文摘The effects of Ag on the microstructure and corrosion behavior of pre-soldering Sn-xAg lead-free solders,and on the formation of intermetallic layer of the solders with Cu substrate were investigated.The Ag contents(x)were 0,3.0,3.5,4.0,and5.0 wt.%.The Ag content played a role in the morphology of Ag3 Sn phase in the solders.The microstructure analysis showed that theβ-Sn phase was surrounded by eutectic networks in the 3.0 Ag and 3.5 Ag solders and large plate-like Ag3 Sn formed in the 4.0 Ag and5.0 Ag solders.Nonetheless,the Ag content slightly impacted the corrosion behavior of the as-cast solders as characterized using potentiodynamic polarization test.After soldering,only a single layer of a Cu6 Sn5 intermetallic compound formed at the Sn-xAg/Cu interface.By comparison,the Cu6 Sn5 intermetallic layer of the Ag-doped solders was thinner than that of the 0Ag solder.The fine Ag3 Sn particles in the eutectic networks precipitating in the 3.0 Ag and 3.5 Ag solders effectively hindered the growth of Cu6 Sn5 grains compared to large plate-like Ag3 Sn in the 4.0 and 5.0Ag solders.
基金the National Natural Science Foundation of China(No.50401033)the Foundation for the Author of National Excellent Doctoral Dissertation of China(No.200335)+1 种基金the Natural Science Foundation of Tianjin City(No.033608811)Scientific Reseaxch Foundation for the Returned 0verseas Chinese Scholaxs,State Education Ministry,for grant and financial support.
文摘Sn-Ag alloy system has been regarded as one of the most promising lead-free solder to substitute conventional Sn- Pb eutectic solder. But the formation of bulk Ag3Sn intermetallic compounds （IMCs） during reflow and post heat treatment significantly influences the performance of the solder joints. With an effort to clarify its microstructural evolution as a function of slow cooling rates, the fraction of bulk IMCs within the slowly solidified Sn-4.0 wt pct Ag solder was investigated by standard metallographic and compared with that detected by thermal analysis. It was found that the bulk IMCs fraction determined by thermal analysis corresponds quite well with the microstructure observation results. In accordance with the conventional solidification theory, the lower the applied cooling rate, the fewer the amount of bulk Ag3Sn IMCs formed in Sn-4.0 wt pct Ag alloy. In addition, Vickers hardness measurement results indicated that the relative coarse eutectic Ag3Sn IMCs distributing in the lamellar eutectic structure favored the improvement of the mechanical performance.
文摘An orthogonal method was used to evaluate the effects of Ga, Al, Ag, and Ce multi-additions on the wetting characteristics of Sn-9Zn lead-free solders by wetting balance method. The results show that the optimal loading of Ga, Al, Ag, and Ce was 0.2 wt.%, 0.002 wt.%, 0.25 wt.%, and 0.15 wt.%, respectively. Intermetallic compounds （IMCs） formed at the interface between Sn-9Zn-0.2Ga-0.002Al-0.25Ag- 0.15Ce solder and Cu substrate were investigated by scanning electron microscope （SEM） and energy dispersive spectroscopy （EDS） analysis. The SEM images illustrate that the IMCs can be divided into two portions from the substrate side to the solder side： a planar CusZns layer and an additional continuous scallop-like AgZn3 layer. The EDS analysis also shows that Ga segregates in the solder abutting upon the interface. X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES） of the surface components of Sn-9Zn-0.2Ga-0.002Al- 0.25Ag-0.15Ce solder indicate that Al aggregates at the surface in the form of Al203 protective fdm, which prevents the further oxidation of the solder surface. On the other hand, Ce aggregates at the subsurface, which may reduce the surface tension of the solder and improve the wettability in consequence.
基金King Mongkut’s Institute of Technology Ladkrabang and the National Research Council of Thailand for the financial sponsorship of this project
文摘The Sn-Cu-Ni-Ge solder is a strong challenger to the Sn-Ag-Cu（SAC） solders as a replacement for the Sn-Pb eutectic solder. This research investigated the effects of addition of Ag, Bi, In, and Sb on the physical properties of the Sn-0.6 Cu-0.05 Ni-Ge（SCNG） lead-free solder and the interfacial reaction with the Cu substrate. The melting behavior, microstructure, tensile strength, and wettability of the SCNG-x（x=Ag, Bi, In, Sb） solders were examined. The findings revealed that the introduction of Ag, Bi, In, and Sb minimally altered the solidus temperature, liquidus temperature, and tensile strength of the solder. However, the cooling behavior and solidified microstructure of the solder were affected by the concentration of the alloying elements. The wettability of the SCNG solder was improved with the doping of the alloying elements except Sb. The thickness of intermetallic layer was increased by the addition of the alloying elements and was related to the cooling behavior of the solder. The morphology of intermetallic layer between the SCNG-x solders and the Cu substrate was different from that of the typical SAC solders. In conclusion, alloying the SCNG solder with Ag, Bi, In or Sb is able to improve particular properties of the solder.
基金Rajamangala University of Technology Rattanakosin and School of Engineering,King Mongkut’s Institute of Technology Ladkrabang for the laboratory support of this research。
文摘The effect of Cu content on the microstructure,grain orientation and mechanical properties of Sn-xCu(x=0-4.0 wt.%)lead-free solder was studied.Results showed that added Cu induced the formation of intermetallic phases.Only theη-Cu;Sn;andε-Cu;Sn phases were present in theβ-Sn matrix.For all contents,the strongly preferred orientation of theβ-Sn phase was formed on the{001}plane.In Sn doped with 1.0 wt.%Cu,theη-Cu;Sn;phase exhibited the preferred orientation of{0001}plane,whereas doping with 3.0 or 4.0 wt.%Cu transformed the preferred orientation to the{010}plane.In addition,only the{0001}and{■}planes were present in theε-Cu;Sn phase.The high Cu contents contributed to an increased number of low-angle boundaries,high residual strain,tensile strength and microhardness.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50401003), the Natural Science Foundation of Tianjin City (No. 033608811) and Fok Ying Tong Education Foundation (No. 104015).
文摘A lead-free Sn-3.5Ag solder was prepared by rapid solidification technology. The high solidification rate, obtained by rapid cooling, promotes nucleation, and suppresses the growth of Ag3Sn intermetallic compounds （IMCs） in Ag-rich zone, yielding fine Ag3Sn nanoparticulates with spherical morphology in the matrix of the solder. The large amount of tough homogeneously-dispersed IMCs helps to improve the surface area per unit volume and obstructs the dislocation lines passing through the solder, which fits with the dispersion-strengthening theory. Hence, the rapidly-solidified Sn-3.5Ag solder exhibits a higher rnicrohardness when compared with a slowly-solidified Sn-3.5Ag solder.
文摘The influence of Mo and ZrO_(2)nanoparticles addition on the interfacial properties and shear strength of Sn58Bi solder joint was investigated.The interfacial microstructures of Sn58Bi/Cu,Sn58Bi+Mo/Cu and Sn58Bi+ZrO_(2)/Cu solder joints were analysed using a scanning electron microscope(SEM)coupled with energy dispersive X-ray(EDX)and the X-ray diffraction(XRD).Intermetallic compounds(IMCs)of MoSn_(2)are detected in the Sn58Bi+Mo/Cu solder joint,while SnZr,Zr_(5)Sn_(3),ZrCu and ZrSn_(2)are detected in Sn58Bi+ZrO_(2)/Cu solder joint.IMC layers for both composite solders comprise of Cu_(6)Sn_(5) and Cu_(3)Sn.The SEM images of these layers were used to measure the IMC layer’s thickness.The average IMC layer’s thickness is 1.4431μm for Sn58Bi+Mo/Cu and 0.9112μm for Sn58Bi+ZrO_(2)/Cu solder joints.Shear strength of the solder joints was investigated via the single shear lap test method.The average maximum load and shear stress of the Sn58Bi+Mo/Cu and Sn58Bi+ZrO_(2)/Cu solder joints are increased by 33%and 69%,respectively,as compared to those of the Sn58Bi/Cu solder joint.By comparing both composite solder joints,the latter prevails better as adding smaller sized ZrO_(2)nanoparticles improves the interfacial properties granting a stronger solder joint.
基金supported by the Jiangsu Six-kind Skilled Personnel Project,China (No.06-E-020)
文摘The eutectic Sn-9Zn alloy was doped with Ag （0 wt.%-1 wt.%） to form Sn-9Zn-xAg lead-free solder alloys. The effect of the addition of Ag on the microstructure and solderability of this alloy was investigated and intermetallic compounds （IMCs） formed at the solder/Cu interface were also examined in this study. The results show that, due to the addition of Ag, the microstructure of the solder changes. When the quantity of Ag is lower than 0.3 wt.%, the needle-like Zn-rich phase decreases gradually. However, when the quantity of Ag is 0.5 wt.%-1 wt.%, Ag-Zn intermetallic compounds appear in the solder. In particular, adding 0.3 wt.% Ag improves the wetting behavior due to the better oxidation resistance of the Sn-9Zn solder. The addition of an excessive amount of Ag will deteriorate the wetting property because the gluti- nosity and fluidity of Sn-9Zn-（0.5, 1）Ag solder decrease. The results also indicate that the addition of Ag to the Sn-Zn solder leads to the precipitation of ε-AgZn3 from the liquid solder on preformed interracial intermetallics （CusZn8）. The peripheral AgZn3, nodular on the Cu5Zn8 IMCs layer, is likely to be generated by a peritectic reaction L ＋ γ-Ag5Zns→AgZn3 and the following crystallization of AgZn3.
文摘Effect of different contents of La and Ga on the wettability and the mierostrueture of interface of Sn-8.9Zn- 2.7Bi trinary alloys was studied. The results show that different contents of La and Ga have significant effect on the wettability of Sn-Zn-Bi based lead-free solder under the condition of both atmosphere and nitrogen. By adding suitable amount of Ga, Cu and La to Sn-Zn-Bi solder, a new lead-free solder Sn-8.9Zn-2.7Bi- 1.0Ga-0.5Cu-0.2La with better wettability was prepared, which has a wetting angle of 25.1° to Cu.
文摘The microstructure and melting behavior of Sn-9Zn-2Cu （SZC） lead-free solder with 3 wt pct Bi and various amount of Ni additions were studied. The wetting properties and the interracial reaction of Sn-Zn-Cu with Cu substrate were also examined. The results indicated that the addition of 3 wt pct Bi could decrease the melting point of the solder and Ni would refine the microstructure and the rod-shape Cu5Zn8 phase changed into square-shape （Cu, Ni）5Zn8 phase. The addition of Bi, Ni greatly improved the wettability of SZC solder. In addition, the interracial phase of the solders/Cu joint was typical planar Cu5Zn8 in SZC-3Bi-INi alloy.
基金supported by the scientific and technological project in Fujian Province(2015H0008)
文摘In the present work, the effect of Ni doping on the microstructures and properties of Zn-20 Sn high temperature lead-free solder has been investigated. Interestingly,Ni was present as the form of Ni-Zn compounds in the microstructure of Zn-20 Sn-xNi alloy.When the Ni-doping amount was 0.2~0.4 wt.%, the presence of δ phase was found, and when the doping amoun was 0.8 wt.%, the presence of γ phase was observed. With the increase of Ni content, the liquidus temperature increased but the solidus temperature did not change obviously. In addition, the microhardness and electrical resistivities of Zn-20 Sn-xNi solder increased gradually. And the spreading area and shear strength increased firstly but decreased afterwards. When the content of Ni was 0.4 wt.%, the spreading area and shear strength of solder reached to be maximum. After the addition of 0.4 wt.% Ni, the microstructure of the interfacial intermetallic compound(IMC) layer of the interface didn't change, but the total thickness of the IMC layer reduced. The δ-phase was embedded in the grain boundary of ε-Cu Zn5, which hindered the diffusion of atoms. The thickness of IMC layer at the interface reduced, which led to the improvement of the shear strength of the interface.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50401003), Fok Ying Tong Education Foundation (No. 104015), and the Natural Science Foundation of Tianjin City (No. 033608811).
文摘An experimental study on the microstructures of a rapid directionally solidified metallo-eutectic Sn-Cu alloy was carried out. This material is an important alloy that is used as a lead-free solder. The results showed that the kinetic undercooling due to the rapid solidification process led to the formation of a pseudoeutectic zone, whereas the hypereutectic reaction produced the regular lamellar structure in the hypereutectic Sn-1.0Cu alloy. The corresponding arm spacing in the obtained lamellar phases decreased gradually with the increase of the applied cooling rate, which corresponded well with the prediction of a rapid directional solidification model.
文摘The Sn-9Zn lead-free solder alloy was prepared by conventional casting technique then cold-rolled into long sheets of 1 mm thickness and 3 mm width. It was annealed at 80, 120 and 160°C for 60 min to investigate the effect of isochronal heat treatment on structure and mechanical properties of the cold rolled Sn-9Zn alloy. The results showed that, the crystallite size and lattice strain have opposite behavior with increasing annealing temperature due to recovery and recrystalization processes associated with the heat treatment process. Vickers micro-hardness number increases continuously from 155 to 180 MPa with increasing annealing temperature. Ultimate tensile strength (UTS) was also calculated. It was found that, it is equal to 61.4 MPa for the non annealed sample and slightly decreases to 60.5 and 58.2 MPa for samples annealed at 80 and 120°C, respectively. While, increases to 65.4 MPa for the sample annealed at 160°C. Also, ductility increases with increasing annealing temperature in opposite manor with the UTS. The new method for Micro-creep behavior as well as the creep rate calculated by this method has been characterized at room temperature.
基金This work contributes to Group Project No. 4, within the frame of European Project COST "Action 531: Lead-free sol-ders". Financial support from Polish State Committee for Scientific Research under grant No. 62/E - 88/SPB/COST/ T08//DZ 459/2003-2006 is gratefully acknowledged.
文摘Emf technique was employed to determine indium activities in the liquid Ag-In-Pd alloys using galvanic cells with yttria-stabilised-zirconia as solid electrolyte according to the scheme： kanthal/rhenium, Ag-In-Pd, In2O3 ｜ YSZ ｜ Ni, NiO, Pt. Composition and temperature measurement ranges were limited, because of very steep liquidus surface; 35 compositions for Xpd up to 0.3 were investigated and at temperatures from near-liquidus up to 1700 K. High temperature experiments required special moly furnace to be constructed with unique automatic gas supply system for fumace winding protective atmosphere. Emf readings were taken and recorded by automatic data acquisition system. Linear dependence of emf on temperature was observed for all compositions investigated, and results were approximated by straight line equa- tions. Then In activities were calculated using well-known relations and taking into account correction for thermoelectric power between kanthal and platinum. Results are to be used along with other existing data to perform assessment of the ternary system under accord.
文摘Conventional planar flow casting(PFC) is one of rapid solidification processes for the fabrication of microcrystalline or amorphous ribbons.Based on the conventional PFC process,the planar flow casting atomization(PFCA) process has been developed,which is a new rapid solidification process for the production of metal powder directly from alloy melts.A prototype experimental apparatus was designed and manufactured.With the apparatus,Sn60Pb40 alloy solder powders were prepared,and the effects of the main technological parameters on the powder size distribution and morphology were experimentally studied.The experimental investigations indicate that the metal powders produced by the PFCA process can be classified by velocity;and fine spherical tin-lead alloy solder powders can be fabricated by adjusting the technical parameters.The new PFCA process has such features as high productivity and efficiency,low energy consumption,simple operation,short technological process,and large gross yield.
基金Project(51004039)supported by the National Natural Science Foundation of ChinaProject(2012713)supported by the Cooperation Promoting Foundation in Science and Technology of Shaoxing City,China
文摘The effect of Sb content on the properties of Sn-Bi solders was studied. The nonequilibrium melting behaviors of a series of Sn-Bi-Sb solders were examined by differential scanning calorimetry （DSC）. The spreading test was carried out to characterize the wettability of Sn-Bi-Sb solders on Cu substrate. The mechanical properties of the solders/Cu joints were evaluated. The results show that the ternary alloy solders contain eutectic structure resulting from quasi-peritetic reaction. With the increase of Sb content, the amount of the eutectic structure increases. At a heating rate of 5 ℃/min, Sn-Bi-Sb alloys exhibit a higher melting point and a wider melting range. A small amount of Sb has an impact on the wettability of Sn-Bi solders. The reaction layers form during spreading process. Sb is detected in the reaction layer while Bi is not detected. The total thickness of reaction layer between solder and Cu increases with the increase of the Sb content. The shear strength of the Sn-Bi-Sb solders increases as the Sb content increases.
