Influence of ZnO nano-particles addition on thermal analysis,microstructure evolution and tensile behavior of Sn–5.0 wt%Sb–0.5 wt% Cu lead-free solder alloy

A.N. Fouda a,n, E.A. Eid b

a Physics Department, Faculty of Science, Suez-Canal University, 41522 Ismailia, Egyptb Basic Science Department, Higher Technological Institute, 44629 10th of Ramadan City, Egypt

a r t i c l e i n f o

Article history:Received 15 December 2014Received in revised form22 February 2015Accepted 25 February 2015Available online 5 March 2015

Keywords:Functional alloysElastic propertiesNano-crystalline structureComposite solderMicrostructure

a b s t r a c t

Sn–5 wt%Sb–0.5 wt%Cu (plain SSC505) and Sn–5 wt%Sb–0.5 wt%Cu–0.5 wt% ZnO (SSC-ZnO) compositesolder alloys have been studied. The variation in thermal behavior, microstructure and tensilecharacteristics associated with mixing of 0.5 wt% ZnO nano-metric particles to plain SSC505 solderwere investigated. A slight increment in the melting temperature [ΔTm¼0.89 1C] was recorded usingdifferential scanning calorimetry (DSC) after addition of ZnO. X-Ray diffraction (XRD) analysis confirmedthe existence of β-Sn, SbSn and Cu6Sn5 intermetallic compounds (IMCs) beside some of ZnO planes inSSC-ZnO composite solder. Field emission scanning electronic microscope (FE-SEM) investigation of SSC-ZnO composite solder revealed a homogenous uniform distribution, size refinement of IMCs and β-Sngrains. Addition of ZnO nano-metric particles into the plain SSC505 enhanced the yield stress σYS by�12% and improved the ultimate tensile strength σUTS by �13%. In addition, adding ZnO nano-metricparticles was found to be effective for reducing ductility by �43% of the plain solder due to therefinement of β-Sn grains within SSC-ZnO composite solder.

& 2015 Elsevier B.V. All rights reserved.

1. Introduction

Sn based alloys are promising for advance electronics compo-nents connections as a lead-free composite solder [1]. Recently,high-temperature solders have been widely used in various typesof applications like assembling optoelectronic components, auto-mobile circuit boards, circuit modules for step soldering, etc. [2].Eutectic composition of gold–tin (Au–20 wt% Sn) is the best solderalloy for most applications in optoelectronic packaging, because ofits high creep resistance, wettability and good reliability [3,4].Certainly, high soldering temperatures could damage the proper-ties of optical fibers and sensitive optoelectronics such as lasers,light emitting devices, photodetectors, or waveguide devices [2,5].To solve this problem, great effort has been made to develop a newgeneration of solders with lowmelting point, reasonable cost, highdimension stability and supporting solder joints performance withincreasing miniaturization and more input/output terminals [6].Sn–5 wt% Sb solder is one of great potential alternative materials,it has a stable microstructure, good mechanical properties, high

creep and corrosion resistance and good solderability (contactangle of about 431) [7,8]. To enhance the performance of Sn–Sbsolders, the incorporation of a third material with Sn-based matrixas a secondary phase is one of the conventional approaches [9,10].Micro/nano size metallic, intermetallic and oxide particles arewidely used in the reinforcement of composite materials [11].Nano-size oxides, intermetallic, or ceramic particles are used toreinforce the composite solders of Sn–Ag and Sn–Ag–Cu (SAC).Many researchers investigated the effect of adding nanoparticlesto solder alloys. Babaghorbani et al. [12] added SnO2 nanopowdersto Sn93.5Ag lead-free solder alloy. Taso and Chang [4] mixed TiO2

nano-size particles to Sn–3.5Ag–0.25Cu solder. They discussed theeffect of adding nanoparticles on the thermal characteristics ofsolder solidification and refinement of the grain size. Nai et al.reported an improvement in the mechanical properties of thecarbon nano-tubes/composite solders [11]. Moreover, some effortshave been made to reinforce Sn–3.5Ag solder with nanopowdersof ZrO2, SiC, Cu, Co, Ni, Ag, and intermetallic particles (Cu6Sn5,Ni3Sn4) using different processing methods [6,12–15]. However,the secondary phase must be sufficiently fine, bond well, stable,has a higher flow resistance than the alloy matrix, un-deformableand resist the fracture of solder joint [16–18].

The literature survey revealed that no studies have beenreported so far on lead-free SSC505 solder joints containing

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journal homepage: www.elsevier.com/locate/msea

Materials Science & Engineering A

http://dx.doi.org/10.1016/j.msea.2015.02.0700921-5093/& 2015 Elsevier B.V. All rights reserved.

n Corresponding author. Tel.: þ20 1227507971.E-mail addresses: alynabieh@yahoo.com (A.N. Fouda),

dr_eid_hti@yahoo.com (E.A. Eid).

Materials Science & Engineering A 632 (2015) 82–87

nano-metric ZnO particles. Therefore, the present work is devotedfor investigating the effect of adding nano-metric ZnO particles onthermal, microstructure and tensile behavior of Sn–5 wt% Sb–0.5 wt% Cu (SSC505) lead free solder.

2. Experimental procedure

Zinc oxide (ZnO) nano-sized particles was selected as a rein-forcement oxide because of its capability to form physical bondwith metallic matrix [19]. Additionally, the main advantages ofnano-sized ZnO particles is: (i) density of (5.67 g/cm3) which isnearly close to density of Sn–5 wt%Sb (7.530 g/cm3) (ii) highhardness [5 GPa], [19] (iii) chemical stability and (iv) low costwhen compared to other nanoparticles such as TiO2, Y2O3, SiC andZrO2. Sn–5.0 wt%Sb–0.5 wt%Cu (plain SSC505) solder alloy wasprepared by melting elements of Sn, Sb and Cu ingots of 99.99%purity. The process of melting was carried out in air at 600 1C for3 h. The SSC-ZnO composite solder was synthesized by mixing andstirring ZnO nano-powder within SSC505 molten alloy. In order toget a homogeneous composition, the alloy was re-melted threetimes to produce rod-like specimen with a diameter of about10 mm. A stainless steel mold was used for casting, then left tocool slowly. The two solder alloys in the form of rods were colddrawn into a wire of 0.8 mm diameter. A part of each alloy wasrolled into a sheet of 0.5 mm thick for microstructure investiga-tions. Specimens with a gauge length of 50 mm were pulled fortensile testing. Prior to the tensile testing, all specimens were heattreated at a temperature of 150 1C for 2 h in air. Then, they werecooled slowly to room temperature in order to stabilize themicrostructure and remove the residual defects which are pro-duced during the cooled drawn process. The densities (ρ) of plainand composite solders were determined using Archimedes prin-ciple. Polished samples taken from various sections of the solidi-fied rods were weighted in air and after immersed in distilledwater using an electronic balance (A&D HM-202) with an accuracyof 70.0001 g.

For metallographic observations, as-solidified specimens wereprepared initially by mounting in cold epoxy. They were neatlypolished using 3 μm and 1 μm alumina powder which suspendedin distilled water as a lubricant. Final polishing to near mirror-likesurface was achieved using 0.3 μm diamond paste. The as-polishedsamples were chemically etched in a solution of 80% glycerin, 10%nitric acid and 10% acetic acid for 10 s. The surface morphology ofthe samples were characterized by using field emission scanningelectron microscopy (FE-SEM) SU8000 series equipped with energydispersive X-ray analysis (EDX). X-ray diffractometer (Philips dif-fractometer (40 kV)) with Cu-Kα radiation (λ¼0.15406 nm) wasused for XRD measurements. The melting temperature and heat offusion were analyzed using a differential scanning calorimetry(DSC-Shimadzu DSC-50). Tensile testing was performed by strainingeach specimen to fracture under a strain rate of 4.7�10�3 s�1 andtesting temperature of 27 1C.

3. Results and discussion

3.1. Thermal behavior

For the soldering process, the melting temperature of solder isa crucial parameter. Because, it is the main factor in deciding theprocess temperature. The melting points of the prepared plain andcomposite solders were accurately determined by DSC thermo-grams. Fig. 1(a and b) shows the endothermic peak of the soldertemperature during the heating rate of 5 1C/min. The meltingtemperatures of the plain and composite solders are 237.38 and

238.27 1C respectively. This result is agree with other previousreports on SAC composite solders [4,20,21]. The slight increase inmelting point of the SSC-ZnO composite solder can be attributedto the effect of the nano-sized ZnO particles on the rate ofsolidification. Such particles may serve as retardation sites forthe solidification process of the IMCs [22].

Additionally, the endothermic peak of DSC curve in Fig. 1 isinitiated at solidus temperature Ts and ended at liquidus tempera-ture TL that is estimated by using the intersection point betweenthe horizontal tangent of baseline and the tangent line for eachside of endothermic peak. The features of endothermic peak ofsynthesized solder alloys are summarized in Table 1. For plainSSC505 and composite solders, there is a significant differencebetween solidus temperatures (ΔTs¼2.11 1C) and a negligibledifference in liquidus temperatures (ΔTL¼0.13 1C). For any alloyto be worthwhile as a solder for electronics industry, it mustpossess certain specific quantities like melting range or pastyrange which is an essential parameter to estimate the timerequired for finishing the soldering process. The pasty range ofplain and composite solder alloys are 23.88 and 21.90 1C respec-tively. The solidus and liquidus temperatures of the synthesizedsolder alloys are lower than Sn–5 wt% Sb binary solder alloy. Onthe other hand, Sn–5 wt% Sb has the smallest pasty range of10.0 1C and a higher melting temperature of 246 1C that provides auseful compromise between them. [9,23]

The heat of fusion (ΔH) plays an important role in packagingtechnology. The calculated heat of fusion for both solder alloys aretabulated in Table 1. The heat of fusion for plain is higher thancomposite solder alloy [ΔHSSC505�ΔHSSC-ZnO¼36.56 J/g]. The con-sumed energy for its melting process is lower than Sn–5 wt% Sb(ΔHSn–5Sb¼140.5 J/g) by �37% [9]. Therefore, SSC-ZnO compositesolder alloy is considered as a promising solder for saving energy.

3.2. Microstructure evolution

3.2.1. XRD analysisRepresentative x-ray diffraction of plain solder and composite

solder are shown in Fig. 2a and b. The diffraction pattern exhibitedsharp peaks, which were attributed to the crystalline nature of the

0 100 200 300 400 500

237.38 °C

238.27 °C

TEMPERATURE (°C)

SSC505

SSC-ZnO

HEA

T FL

OW

(mW

)

Fig. 1. DSC curves of (a) SSC505 and (b) SSC-ZnO composite solder alloys.

Table 1Comparison of melting temperatures (Tm), solidus temperature (Ts), liquidustemperature (TL), pasty range (ΔT) and heat of fusion (ΔH) for various solder alloys.

Material Tm (1C) Ts (1C) TL (1C) ΔT¼TL-TS (1C) ΔH (kJ/kg) Reference

Sn–5Sb 246 240 249 9.0 141 El-Dally [9]SSC505 237.38 223.45 247.33 23.88 125.52 This studySSC-ZnO 238.27 225.56 247.46 21.90 88.96 This study

A.N. Fouda, E.A. Eid / Materials Science & Engineering A 632 (2015) 82–87 83

samples. The qualitative analysis of the peaks reflects the existenceof body center tetragonal of β-Sn-rich phase. The diffraction planes(101), (110), (021), and (202) at angles of (2θ¼29.31, 41.91, 42.31and 60.51) respectively, confirm the existence of cubic SbSn IMC.Regarding to Fig. 2b, it consists of the same phases which exist inthe plain solder (Fig. 2a). On the other hand, the emergence of ZnO(101) and (002) peaks at angles of 32.71 and 34.31 is an evidence ofZnO nanoparticles dispersion within β-Sn matrix. Moreover, dis-appearance of some ZnO peaks can be attributed to interfere of itspeaks with the peaks of β-Sn phases. However, the slow scanspeed (0.02 deg/s) conducted on the plain and composite soldersrevealed several peaks at angles of (2θ¼30.361, 42.881, 53.651,57.581, 62.331 and 79.711) that corresponds to Cu6Sn5 IMC. Thesmall peaks of Cu6Sn5 IMC assigned to the low volume fraction ofthe copper in the solder matrix. Fig. 3, shows a comparisonbetween diffraction peaks (200) and (101) of β-Sn for plain andcomposite solder. One can observe that, the diffraction lines are

slightly shifted towards lower angles, indicating the increase ofstrain with addition of ZnO nano-metric particles [24,25].

It is well known that, the broadening of XRD peaks of an alloy iscaused not only by the small grain size but also due to the latticemicro-deformations of the alloy [15]. The crystallite size d and anapproximate upper limit of the lattice strain ε can be evaluated byXRD peaks analysis according to the Williamson–Hall formula [25]:

β cos θ¼ kλdþ2η sin θ ð1Þ

where β is the peak width at half maximum intensity (FWHM) inradian of the main peaks, θ is the Bragg angle, k is the Scherrerconstant (k¼0.9), η is the average of lattice strain, and λ is the X-raywavelength (λ¼0.15406 nm). When β cos θwas plotted against sin θusing the main peaks of β-Sn, a straight line is obtained with theslope of 2η and the intercept as (kλ/d). Results of linear fitting ofextracting data are summarized in Table 2. The crystallite size of Sn-based supersaturated solid solution was calculated to be 116 and99 nm for the plain and composite solders, respectively. FromTable 2, one can observe that the average lattice strain η of β-Snphase for SSC-ZnO composite solder was higher than plain solder by550%. The increment in the strain η can be attributed to thegeneration of additional impurity defects during the preparation ofSSC-ZnO composite solder [26]. Moreover, the micro-strain is accom-panied by dislocation which make broadening in XRD peaks [24].

3.2.2. Metallographic observationsResults of microstructural characteristics of the plain and

composite solders are discussed in terms of: (i) grain size,morphology, and homogenous distribution, (ii) the presence,distribution and morphology of second phase particles, and(iii) percentage of porosity, cracks and voids. Fig. 4 shows twooptical images (OM) with the same power of magnification for theas-cast plain and composite solders that solidified at cooling rateof 2 1C/min. Results revealed that the plain solder was composedof larger non-equiaxed grains, non-uniform solidification micro-structure; the large dark islands are rich-Sn grains with grain sizein the range of 100–140 μm. The bright region between Sn grainsactually consists of mixture of lamellar phases of Sn matrix phase(dark phase) and the circular bright dot phase termed as SnSb IMC.Moreover, homogenous distribution and narrower dendrites areshown in Fig. 4b. The finer rich-Sn grains within composite solderreveal near-equiaxed grains with average grain size in the range of90–50 μm approximately. The decrease of average grain size ofβ-Sn phase after adding 0.5 wt% Zinc nano-metric particles can beattributed to its pinning action on grain boundaries and by thesecond phases resulting in limited grain growth [18]. In Fig. 4b, theβ-Sn phase is not only composed of pure Sn crystals but rathercontain several of tiny intermetallic particles that scatteredthroughout Sn matrix. It was revealed from the transmissionelectron microscopy (TEM) image of ZnO nano-powder (seeFig. 5) that the average grain size of ZnO nanoparticles is around66 nm. Furthermore, with higher magnification of field emissionscanning electronic microscope (FE-SEM), the precipitated parti-cles like as platelets or scallop morphology of the Cu6Sn5 IMC wereobserved in both solders (see Fig. 6a and b).

The precipitation of IMCs within β-Sn matrix is confirmed byutilizing energy dispersion X-ray (EDX) analysis, the eutectic areaswere found to contain Zn, O, Cu, Sb and Sn elements in compositesolder. Thus, it can be concluded that the network eutectic areasare Cu6Sn5 and SbSn beside ZnO particles as shown in Fig. 6a–c.Stoichiometric analysis of EDX data implies the existence of Sn, Sband Cu atoms and termed IMCs according to the atomic ratio ofeach element in compound [see Table 3]. An identified decrease insize of SbSn, Cu6Sn5 IMCs was confirmed by FE-SEM images(see Fig. 5a and b). This was assigned to ZnO nanoparticles which

30 40 50 60 70 80

INTE

NSI

TY (a

rb.u

nits

)

2θ (degree)

INTE

NSI

TY (a

rb.u

nits

)

Fig. 2. XRD profiles of (a) SSC505 solder and (b) SSC-ZnO composite solder alloys.

30.2 30.4 30.6 30.8 31 31.2 31.4 31.6 31.8 32 32.2 32.4 32.6

2θ (degree)

Inte

nsity

(arb

.unt

)

SSC505 SSC-ZnO

Fig. 3. Comparison between diffraction peaks of (200) and (101) of β-Sn for plainand composite solders.

A.N. Fouda, E.A. Eid / Materials Science & Engineering A 632 (2015) 82–8784

incorporated into the solder matrix. According to the adsorptiontheory, increasing the adsorption of elements could decrease thesurface energy and/or decrease the growth of IMCs size [14]. Forthe composite solder, the micro-size of SbSn and Cu6Sn5 IMCs arelarger than the size of the ZnO nano-metric particles. Therefore,the incorporation of active surface ZnO nano-metric particles

refines the size of IMCs. Similar behavior was reported by othergroups [20,22].

The Curve of EDX analyses of a selected area in Fig. 7b shows that,the Cu6Sn5 IMC contain 7.01 at% of Sb element [see Table 3]. Theexistence of antimony atoms inside the Cu6Sn5 grain confirms thattin–antimony intermetallic compound might be the nucleating agentacting as a heterogeneous nucleation of Cu6Sn5 grains. The proposedmechanism for the effect of Sb on IMC formation can be summarizedas follows; because Sb has higher affinity to the constituent elementof Sn in Sn–Cu–Sb ternary system, it can reduce the activity of Sn atthe Sn–Cu interface by forming SnSb compound, making a decreasein driving force for Cu–Sn IMC formation [27]. SnSb particles may beinitially formed and finely dispersed in the molten solder, and thensome of them precipitate and become the heterogeneous nucleationsites of Cu6Sn5 IMC. According to the theory of heterogeneousnucleation, the Cu6Sn5 phase prefers to nucleate on the SnSb surfacein order to reduce the thermodynamic barrier [28]. The increase innucleation probability of Cu6Sn5 grains consequently lends to therefinement of the grains. As a result, the small and uniform grains inthe composite solder slow down the ripening rate, and the refine-ment effect is achieved.

3.3. Density measurement

The density measurements were conducted on the solidifiedplain and composite solders. In Table 4, all the density values werevery close which is predicted because of the slight difference indensity between Sn and ZnO. The porosity measurement was

Table 2The average crystallite size (d) and lattice strain (η) for plain SSC505 solder, SSC-ZnO composite solder and SbSn, Cu6Sn5 IMCs.

β-Sn (Matrix) SbSn (IMC) Cu6Sn5 (IMC)

SSC505 (R2¼0.042) SSC-ZnO (R2¼0.061) SSC505 (R2¼0.3337) SSC-ZnO (R2¼0.6108) SSC505 (R2¼0.4255) SSC-ZnO (R2¼0.7218)

d (nm) η�10�5 d (nm) η�10�5 d (nm) η�10�5 d (nm) η�10�5 d (nm) η�10�5 d (nm) η�10�5

116 10 99 55 693 300 116 565 754 346 205 588

ββ-Sn

β-Sn

Fig. 4. Optical images showing the grains of (a) SSC505 solder and (b) SSC-ZnOcomposite solder alloys.

Fig. 5. TEM image of ZnO nano-powder.

Cu6Sn5

SbSn

Cu6Sn5

SbSn

Fig. 6. FE-SEM micrographs showing the grains of (a) SSC505 solder and (b) SSC-ZnO composite solder alloys.

A.N. Fouda, E.A. Eid / Materials Science & Engineering A 632 (2015) 82–87 85

theoretically calculated and tabulated in Table 4 [12,24]. The valueof porosity implied that the higher percentage of pores exists inthe case of SSC-ZnO composite solder.

3.4. Strengthening effect

Fig. 8 shows the typical tensile stress–strain curves of plainand composite solders stretched with constant strain rate of7.4�10�3 s�1 at room temperature (27 1C). The stress–straincurves exhibited plateau shaped with steady stable flow stress ofthe two solder alloys. It was found to be strongly dependent onalloy composition of the tested material. Furthermore, steady stateflow of composite solder was higher than plain solder by �12%.This observation can be explained as; during plastic deformationthe solder alloy suffers from simultaneous work hardening anddynamic recovery [17]. They have contrary influences on themechanical deformation of the alloy. Hence the steady stablestresses seem to be represented equal combination effects. Addi-tionally, existence of the ZnO nanoparticles increases dislocationdensities because of their restricting effect for the motion ofdislocation, besides the dispersion hardening mechanism of theIMCs. Therefore, during deformation, the movement of generateddislocations becomes mixed and tangled. It is then more difficult forother dislocations to glide through the material, especially at lowertesting temperatures leading to increase the flow stresses [20].

The average values of Young modulus E, ultimate tensilestrength σUTS, yield stress σYS, fracture stress σf and ductility ε of

Table 3Energy dispersive R-Ray (EDX) analysis.

Zone Composition Phase identification

Sn Sb Cu Zn O2

Wt% At% Wt% At% Wt% At% Wt% At% At% Wt%

þ (See Fig. 6a) 65.43 66.01 34.57 33.99 – – – – – – SnSbþ (See Fig. 6b) 72.76 61.61 3.68 7.01 23.56 27.37 – – – – Cu6Sn5

þ (See Fig. 6c) 83.59 40.53 8.75 6.61 2.06 2.98 3.51 4.94 3.60 13.08 Eutectic

0 1 2 3 4 5 6 7 8 9 10Energy (keV)

Sn

Sn

Sn Sn

Sn

Sb

Sb

Sb

SbSn

+

0 1 2 3 4 5 6 7 8 9 10Energy (keV)

Sn

Sb

Sn

AB

SnCu CuCu

Cu6Sn 5

Sn

0 1 2 3 4 5 6 7 8 9 10

Energy (keV)

Sn

SbSn

SnCu

ZnSn Cu

O2

Fig. 7. High-magnification FE-SEM micrographs with corresponding EDX of inter-metallic compound of (a) SbSn (b) Cu6Sn5 (c) eutectic region in SSC-ZnO compositesolder.

Table 4Results of density and porosity.

Material Density (g/cm3)a Porosity (g/cm3) Reference

Sn–5 wt% Sb 7.52670.005 0.50 El-Bahay [23]SSC505 7.55370.006 0.7570.17 This studySSC-ZnO 7.53370.006 0.8770.20 This study

0.00 0.05 0.10 0.15 0.200

20

40

60

80

100

SSC505

STR

ESS

(MPa

)

STRAIN

SSC-ZnO

Room temperature

ε.=4.7×10-4 s-1

Fig. 8. Stress–strain curves showing the effect of adding 0.5 wt% ZnO nanoparticlesto SSC505 plain solder alloy.

A.N. Fouda, E.A. Eid / Materials Science & Engineering A 632 (2015) 82–8786

the synthesized solder alloys were tabulated in Table 5. Addition of0.5 wt% ZnO nano-powders has a significant effect on the tensileparameters. Detectable increments in E by 52%, σUTS by 11% and inσYS by 13% were recorded. However, the ductility ε of SSC-ZnOcomposite solder was less than plain solder by 43%. Improvementin the tensile parameters was achieved because of presence of ZnOnanopowders as reinforcement agent. The nano-sized particles aredispersed uniformly and homogeneously distributed in Sn matrixwhich provide high barrier for grain boundary sliding and dis-location movement. The reinforcement nanoparticles play twodifferent roles. They may strengthen the alloy matrix and enhancethe formation of large dislocation pile-ups at grain boundaries.Simultaneously, the higher friction of nanoparticles generatesmicrocracks nucleation at the interface between Sn matrix andIMCs which speed up the failure process [29,30]. So, ductility wasdecreased because of a large amount of microporosity throughoutgrain boundaries and crack nucleation sites in the form of hardand brittle ZnO nanopowders [20,24,31].

Eventually, the influence of the nano-metric size particles canbe summarized in: (i) pinning grain boundaries and thus impedingsliding of the grain boundaries, (ii) the increase of dislocationdensities and obstacles to restrict the motion of dislocation and(iii) the dispersion hardening mechanism of the IMCs and ZnOnanopowders [30,32].

4. Conclusion

ZnO nano-sized particles were mechanically mixed with themolten of SSC505 at 600 1C during the fabrication of SSC-ZnOcomposite solder. Thermal behavior, microstructure and mechan-ical characteristics were discussed. The melting point of SSC505solder is slightly increased after the addition of ZnO nanoparticles.X-ray diffraction analysis of SSC-ZnO confirms the existence ofSbSn, Cu6Sn5 IMCs and ZnO. The microstructure observationsrevealed finer IMCs due to active surface area of ZnO nanoparticlesthat supports the strong adsorption effect. According to the tensile

measurements, an improvement in σUTS and σYS were established.However, the ductility of SSC-ZnO composite solder was dec-reased. The variation in tensile properties is attributed to ZnOpinning effect which obstructed dislocations and migration ofgrain boundaries.

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Table 5Tensile results at room temperature and strain rate of 4.7�10�3 s�1.

Material E (GPa) σUTS (MPa) σYS (MPa) σf (MPa) εf % Reference

Sn–5 wt% Sbn 44.5 35.50 25.70 – 22 El-daly [9]SSC505 43.4 77.48 64.68 42.59 17.0 This studySSC-ZnO 60.3 86.35 73.10 72.80 9.7 This study

A.N. Fouda, E.A. Eid / Materials Science & Engineering A 632 (2015) 82–87 87