effect of ZnO nanoparticles on thermal, microsture and tensile properties of SSC505 lead free solder...

8/10/2019 effect of ZnO nanoparticles on thermal, microsture and tensile properties of SSC505 lead free solder alloys (Sn_5S

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Influence of ZnO nanoparticles addition on thermal, microstructureand tensile properties of

Sn-5.0 wt%Sb-0.5 wt%Cu (SSC505!ead-free solder allo"

A. N. Fouda a , El Shazly M. Duraia a,, E. A. Eid b

(a) Physics department, Faculty o Science, Suez!"anal #ni$ersity, %&' smailia, E*ypt (b) +asic Science Department, i*her -echnolo*ical nstitute, & th o /amadan "ity, E*ypt.

#bstractFor de$elopment o a lead! ree composite solder or ad$ance electronics components

connections, a *roup o Sn!'Sb! .'"u (SS"' ') and Sn!'Sb! .'"u! .'0n1 (SS"!

.'0n1) lead ree solder alloys ha$e been in$esti*ated. /esults o di erential scannin*

calorimetry appear the addition o .' 2t.3 0n1 nano particles satis y insi*ni icantincreasin* in meltin* temperature 4 - m 5 .67 o"8. Field emission scannin* electronic

microscope (EF!SEM) ima*es o SS"! .'0n1 composite solder re$ealed a uni orm

distribution and re inement !Sn *rain sizes, "u 9 Sn ' and SnSb intermetallic compounds

( M"s). Presence 0n1 nano!po2der in solder matri: enhanced their yield stress y

( . 3;S) and ultimate tensile stren*th #-S , but their ductility reduced due to embed the

nanoparticles in *rain boundaries. 0n1 pinnin* e ect obstructed the motion o

dislocations and has hi*hly acti$e sur ace area that supports the stron* adsorption e ect

o "u atoms.


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Introduction

the public a2areness o

en$ironmental issues and increasin* ?no2led*e o hazards to:ic materials has been

2ea?enin* up lately. /ecently, the strict le*islations put to eliminate the use o lead!basedsolders because o the healthy concerns o$er the to:icity o lead (Pb). n last decade *reat

e orts are pro$ided an ine$itable moti$ation orce or de$elopment o lead! ree solder

alloys. Further, the modern technolo*ical de$elopment in the electronic pac?a*in*

industry met challen*es to2ards miniaturization and unctional density enhancement.

-hese re@uire much smaller solder oints and Bne pitch interconnections or

microelectronic pac?a*in* in electronic de$ices. For e:ample, portable electronic

de$ices, such as portable computers and mobile phones, ha$e become thinner and smaller

2ith more complicated unctions. Mechanical beha$iors o solder alloys are acti$e and

play an important role because o their hi*h homolo*ous temperatures (-C- m .').

Moreo$er, the electronic assemblies are made up rom materials 2ith a 2ide ran*e o

thermal e:pansion coe icients ("-E). Durin* the s2itchin* on and o electronic

de$ices, the chips in electronic de$ices heat up and cool do2n, thus su erin* rom lo2

cycle thermo!mechanical ati*ue (-MF) due to stresses that de$elop as a result o

mismatch bet2een the solder, the substrate and the components 48. -hese -MF cycles

cause plastic strainin* o solder. ence, the de ormation imposed on the solder oints

durin* their operation is time dependent in the metallur*ical sense.

For instance, because o the creep o solder, time!dependent and *radual

misali*nment bet2een a solid state laser chip and a spherical lens on a Bbre in li*ht *uide

ocean cables 2ill reduce the transmission intensity or e$en cause complete loss o the

li*ht 2a$e communication si*nals in the cables 468. n de ense applications, the

mechanical $ibration o tan?s, airoplanes or missiles 2ill create hi*h re@uency

$ibrational ati*ue conditions or solder oints in the attached electronic components andlead these 2eapons to ail. ence, hi*hly creep and ati*ue resistant lead! ree solders

must be de$eloped to sol$e these problems.


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-he solders containin* ' percent antimony or sil$er are pre erred or electrical

e@uipment because o their *ood electrical conducti$ity. -he tin! and lead!based babbitts

(2hite metals) ha$e the lon*est history 4 8 but they are not ade@uate or most applications

in automoti$e en*ines. -he correlation o the alloys= structure 2ith mechanical and

electrical properties o metallic bearin* materials has been a topic o interest or se$eral

years attractin* the attention o many in$esti*ators 4 78. Most o the studies ha$e been

ocused either on mechanical or electrical properties or on microstructure eatures.

Since many Sn!rich solder alloys, includin* Sn!'3Sb and Sn! .'3A*,

*enerally ha$e a hi*her meltin* point than that o Pb!Sn eutectic, they may not be

suitable as replacement or Pb!Sn eutectic. o2e$er, they can be candidates or thereplacement o the Pb!rich solder alloys, such as Pb! 3Sn, Pb!& 3Sn, and Pb!'3Sn,

2hich ha$e a li@uidus temperature hi*her than 6 o" -he Pb!rich solders ha$e been

e:tensi$ely used or lip chip connection, and solder ball connection, 2here either Si

chips or modules are mounted onto a ceramic substrate.

Se$eral electronic applications o Sn!'3 Sb solder ha$e been reported,

includin* hermetic sealband o multichip modules, bondin* a semiconductor de$ice

onto a substrate, G and oinin* o C1 pins to multilayer ceramic substrates. s n the

oinin* C1 pins, Au! 3Sn braze alloy 2as replaced by Sn!'3Sb solder, thus

realizin* se$eral ad$anta*es, such as lo2erin* the oinin* temperature by about ' H

and reducin* the stress induced due to the oinin* process. n addition, Sn!'3Sb

solder oints o er *ood stren*th and creep properties or the application. n another

application, Sn!'3Sb solder 2as used as corrosion protection coatin* to a steel

plate, as 2ell as an electrically conducti$e area 2hich could be used or subse@uent

*roundin*. A small addition o Sb to the Pb!Sn eutectic solder has been reco*nized or a

lon* time to impart se$eral bene icial e ects, such as pre$ention o tin pest, H

stren*th impro$ements, and creep resistance. Antimony addition to the pure Sn

metal *enerally con irms the same bene icial e ects obser$ed 2ith the Pb!Sn eutectic

solder. n -able , a si*ni icant increase in shear stren*th is noted or solder

oints made o Sn!'3 Sb solder in comparison 2ith those made o the pure Sn.


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-able I also sho2s a better thermal ati*ue li e o P- oints made 2ith Sn!'3Sb

than those o pure Sn. o2e$er, one dra2bac? is reco*nized 2ith Sn!'3Sb solder

in terms o solderability as sho2n in -able I. -he solderability o Sn!'3Sb, as

measured by the percent spread o a 2ettin* area, is lo2er than that o the Pb!Sn

eutectic, and it is also reduced by addin* Sb to pure Sn. -he addition o Sb into pure Sn

can be harm ul to the mechanical properties 2hen the Sb le$el approaches the

solubility limit in Sn, 2hich is about & 3 by 2ei*ht at ' H ' -his is attributed to an

e:cessi$e ormation o the cubic intermetallic phase, SnSb 9 #nli?e the Pb!Sn system,

the Sn!Sb system e:hibits a peritectic reaction 2hereby the Sn!rich primary solid

solution is ormed at ' H -he microstructure o the Sn! '3Sb solder oints is,

there ore, e:pected to be hi*hly dependent upon the solderin* process and the thermal

e:posure a ter2ard.

1 the lead! ree solders de$eloped, only the hi*h meltin* point Sn 6 Au alloy

can 2ithstand hi*h temperature ser$ice conditions. o2e$er, this alloy cannot be utilized

in a 2ide ran*e o manu acturin* situations due to its cost and the de*radation o the

properties o electronic components by hi*h temperature solderin*.

-o sol$e this problem, e orts ha$e been made to de$elop solders 2ith a lo2

meltin* point and hi*h creep resistance. ence, much research has been carried out on

the addition o a third element (+i, Al, "u or A*) into the Sn Sb peritectic solder alloys

to impro$e the 2ettin* characteristics and creep resistance4:8. Moreo$er, another

potentially $iable and economically a ordable approach is the addition o discrete

secondary particles to the solder matri: so as to orm a composite solder 4:8.

Published literature sho2s that, to obtain the reBnement and stable microstructure

o a solder alloy an addition o discrete secondary particles 2as mi:ed to a solder matri:

to orm a composite solder. -hese studies indicate that the addition o secondary particles

to a lead! ree solder matri:, and thereby the ormation o a dispersion!stren*thened

solder, is a $iable approach to preparin* lead! ree solder 2ith enhanced mechanical

properties. -he rein orcement particles used in the composite materials usually included

micro!Cnano!size metallic, intermetallic, or o:ide particles. Ma$oori et al. 4J8 de$eloped


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a Pb! GSn based solder 2ith & nm Al 1 and ' nm -i1 rein orcement particles and

reported si*ni icant impro$ements in creep resistance and mechanical properties.


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addition, the tensile properties o the SS"' ' and SS"!0n1 solder is measured to

e:plore the potential stren*thenin* e ect o 0n1 nanoparticles on the prepared solder.

$- &perimental procedures

A lead! ree solder, Sn '. 2t3Sb .' 2t 3"u (SS"' ') solder alloy, is preparedrom Sn, Sb and "u in*ots o 77.77 3 purity. SS"' ' lead ree composite solder 2as

prepared by mechanically mi:in* .' 2t3 o nano!sized 0n1 particles into the prepared

con$entional SS"' ' lead ree solder 2ith subse@uent remeltin* in a $acuum urnace at

9 or h. -he in*ots 2ere used or our times in order to obtain a homo*eneous

composition, then ollo2ed by castin* into a stainless steel mold ollo2ed by slo2ly

cooled to room temperature. -he t2o alloys in the orm o bars 2ere cold dra2n into a

.6 mm diameter 2ire. A part o each alloy 2as rolled into a sheet o .% mm or

microstructure in$esti*ations. Specimens 2ith a *au*e len*th o ' mm 2ere prepared

or tensile testin*. Prior to the tensile testin*, all specimens 2ere heat!treated at a

temperature o 7 or .' h and then slo2ly cooled to room temperature to stabilize

microstructure and remo$e the residual de ects produced durin* the cold dra2n process.

For metallo*raphic obser$ations, as!solidi ied specimens 2ere prepared initially

by mountin* in cold epo:y. -his 2as ollo2ed by an initial coarse *rind or remo$in* the

cuttin* layer and mechanically polished on pro*ressi$ely iner *rades o silicon carbide

impre*nated emery paper usin* copious amounts o 2ater as the lubricant. -he samples

2ere then ine polished usin* & m and m alumina po2der suspended in distilled 2ater

as the lubricant. Final polishin* to near mirror!li?e sur ace inish 2as achie$ed usin*

. m diamond paste suspended in distilled 2ater.

-he as!polished samples 2ere chemically etched in a solution o 6 3 *lycerin,

& 3 nitric acid and & 3 acetic acid or a e2 seconds. -he etched sur aces o the solder

samples 2ere obser$ed in an optical microscope 2ith the ob ecti$e o determinin* thesize and morpholo*y o the *rains, and presence, distribution, and morpholo*y o other

phases present in the microstructure. -he structure and morpholo*ies o the as!

prepared materials 2ere characterized by J!ray di raction (/i*a?u DCma:! J!ray

di ractometer 2ith "u radiation ( 5&.'%&G6), step size 5 . , & O O7 ),


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ield emission scannin* electron microscopy (FESEM, S#6 Series e@uipped 2ith

ener*y dispersi$e J!ray analysis (EDJ), &' ?I) and transmission electron

microscopy (-EM, itachi, EM! & , ?I), respecti$ely.

DS" measurements 2ere carried out under the protection o hi*h purity nitro*en*as atmosphere to a$oid any une:pected o:idation. -he applied thermal treatment

procedure in the calorimetric e:periment 2as as ollo2sK the specimen 2as irst heated

rom room temperature up to '% at a constant rate o & min Q&.

-ensile tests 2ere carried out by strainin* each specimen to racture. Stress strain

measurements 2ere per ormed at di erent strain rates ran*in* rom &.G:& !% to&:& ! s!&

at di erent testin* temperatures ran*in* rom 76 to G usin* a computerized tensile

testin* machine described else2here 4 8.

3- Results and Discussion:

'- )hermal properties *eltin+ eha ior

Fi*ure & e:hibits DS" thermo*rams o S""' ' and S""! .'0no solder alloy, a

ne*li*ible e ect or risin* the meltin* temperature 2as obser$ed bet2een them ( - m 5

.67 o"). o2e$er, the meltin* temperature o the SS"' ', and SS"! .'0n1 are G. 6,

6. Go" respecti$ely, these results ha$e *reat si*ni icance 2hen compared 2ith meltin*

temperature o Sn!'2t3Sb (- m 5 %9 o") 2hich is considered as baseline or hi*h

meltin* lead! ree solders.

ast" /an+e

-he most distinct common eatures o endothermic pea?s summarized in table &. -hey

are initiated at solidus temperature R- onset R (solid phase initiate to con$ert to a li@uid phase) and

ended at li@uidus temperature - endset (solid phase completely chan*ed to li@uid phase).

orth2hile, solidus temperature and li@uidus temperature are estimated by usin* intersection point bet2een the horizontal tan*ent o baseline and the tan*ent line or each side o

endothermic pea?, the di erence bet2een li@uidus (-


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process ( ). From table (&) it is seen that, the solidus and li@uidus temperatures o SS"' '

solder alloy are .%' o" and %G. o" respecti$ely, its pasty ran*e is (-

to estimate the pasty ran*e o SS"!0n1 (-

li@uidus temperature (- < ), pasty ran*e ( -5-

solder alloys

Solder alloy - m o" - s o" - < o" -5 - < !- S o" ( C*)

Sn!'SbSn!'Sb! .'"uSn!'Sb! .'"u! .'0n1

%9G. 66. G

%.%'

'.'9

%7%G.%G.%9

7..66

&.7

& '.'66.79

!atent eat of 1usion


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& '.' and 66.7G C*, respecti$ely. -hese results re lect that, the SS"! .'0n1 has lo2ered

consumed ener*y or meltin* process than SS"' ' solder.

'.$ *icrostructure Characteri2ation

J!ray di raction in$esti*ation o SS"' ' solder and SS"! .'0n1 composite

solders are illustrated by the di raction pro iles sho2n in Fi*. a!b. -hey are e:hibited

three types o phases> !Sn, SbSn and "u 9Sn ' ( M"s). -he di raction pro iles o both

solders are analysis, and deduced that, they ha$e same unit cell o body central tetra*onal

(+"-) lattice eatures.

-he di raction pea?s inde:ed to Sn clearly e:ist or both o in$esti*atin*

samples, but no pea?s belon*in* to 0n1 appear. -he e:amined J/D pattern o the

SS"' ' e:hibited a reduced pea? intensity compared to J/D pattern o SS"!0n1,

but the relati$e ma*nitude o the pea?s remains the same. n addition, increased

pea? broadenin* 2as obser$ed 2ith present 0n1 nano sized particles. -he a$era*e *rain

size o the !Sn 2as calculated rom the di raction pea? 2idth usin* the Scherrer

e@uation. As it is 2ell ?no2n, *rain size 2as ound to !!!!!!. -he SS"!0n1

composite solder alloy has an a$era*e *rain size o & nm, 2hich is si*ni icantly

smaller than the &G' nm obtained rom the unrein orced Sn coatin*. -he presence o 0n1 in a metal matri: may induce smaller *rains due to a lar*e increase o

nucleation sites. Namely, the *ro2th o the "u 9Sn ' is a competition bet2een nucleation

and crystal *ro2th. -he 0n1 nano particles pro$ide more nucleation sites and, hence,

slo2 up the crystal *ro2th> subse@uently, the correspondin* Sn matri: and Sb in

the composite has nearly a similar crystal size . -he de ects on the SS"!0n1 pro$ide

acti$e nucleation sites or the Sn and produce core!shell!li?e structures, 2hich 2ere

reported to be bene icial or accommodatin* stresses arisin* rom $olume increase :

durin* intercalation.


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Moreo$er, optical microscope ma*es (1M) or the microstructure o SS"' '

solder alloy and SS"! .'0n1 composite solder are sho2n in Fi*. a!b. Fi*ure b

e:hibited a si*ni icantly reduction in the *rain size o the !Sn matri: o the SS"!0n1

composite solder 2hen compared 2ith those in the SS"' ' solder alloy as sho2n in Fi*.

a. Also it can be obser$ed that, durin* solidi ication dendritic net2or? 4 !Sn, dar?

re*ions8 and interdendritic 4bri*ht re*ions8 consistin* o 2hite dots particles 4SnSb M"8

besides irre*ular platelets shapes 4"u 9Sn ' M"8. -hese particles identi ied by study o J!

ray di raction pea?s and the ener*y dispersi$e J!ray analysis (EDJ). Fi*ure a is

depicted the bri*ht dots o SnSb particles dispersed 2ithin the Sn!rich matri: besides

irre*ular poly*ons o "u 9Sn ' intermetallic compounds ( M"s). Fi*ure b re$ealed the

microstructure o the SS"! .'0n1 composite solder alloy. t represents the same eatures

in the microstructure o the SS"' ' solder. Mean2hile, the !Sn dendrites are uni ormly

re ined distributes as 2ell as the M"s particles are reduced in size, 4i.e. seem to be

small and ine compared 2ith those in SS"' ' solder alloy8, this is due to 0n1 nano!

sized play an important role to promote a *reat uni orm nucleation seeds durin*

solidi ication. Moreo$er, Moreo$er, 0n1 nano!particles ha$e hi*hly acti$e sur ace area

that support the stron* adsorption e ect o "u atoms, there ore reduced the e:cessi$e

*ro2th o "u 9Sn ' M" 2ithin S""! .'0n1 composite lead ree solder. (re .)

-he presence o these M"s is con irmed by EDJ analysis that e:hibited in Fi*.

%a!b. -he addition o .' 2t3 nano!sized 0n1 particles has *reat e ect on microstructure

o SS"' ' solder.

Accordin* to the EDJ analysis illustrates in Fi*. %a!b, the in$esti*ated area o

specimens 2as contained 0n, 1, "u, Sn and Sb atoms. -his means that, the presence o

0n1 to SS"!' ' alloy suppress the ormation o the !Sn dendrites, SnSb and "u 6Sn '

( M"s) yieldin* a uni orm dispersion 2ithin the Sn!rich mi:ture that *eneratin* a ine

net2or? microstructure 2ith the !Sn matri:.


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'-' *echanical properties

Fi*. sho2s the typical tensile stress strain cur$es o the lead ree composite solder

specimens at a constant strain rate o &:& ! s!& at di erent temperatures. -he a$era*e$alues o tensile stren*th and elon*ation o the lead! ree composite solder alloys are

*i$en in -able . -he lead! ree SA" solder had an ultimate tensile stress (#-S) o ''.G

MPa, . 3 o set strain ( . ;S) o ' . MPa, and elon*ation o %6.93. Addition o 0n1

nanopo2der had a si*ni icant e ect on the #-S o lead! ree SS" composite solders. For

e:ample, the #-S and . ;S rose to G .& MPa and 97. MPa, respecti$ely. o2e$er, the

total elon*ation o the lead! ree SS" solder containin* 0n1 nanopo2der 2as less than

that o the lead! ree SS" solder ( '. 3 $s.%6.93). -he in luence o 0n1 nanopo2der

rein orcement on tensile properties o the SS" composite solder is also summarized in

-able . /esults re$eal that the tensile properties o the composite solder rises 2ith

increased addition o 0n1 nanopo2der to a lead! ree SS" mi:ture. -his indicates that i

the 0n1 nanopo2ders addition is increased, the composite solder can be impro$ed due to

the presence o 0n1 nanopo2ders as rein orcement.

-his could be attributed toK (&) pinnin* *rain boundaries and thus impedin* slidin* o the

*rain boundaries, ( ) the increase o dislocation densities and obstacles to restrict the

motion o dislocation and ( ) the hardenin* mechanism o the matri: and 0n1

nanopo2ders 48. o2e$er, ductility decreased because o a lar*e amount o micro!

porosity alon* *rain boundaries and crac? nucleation sites in the orm o hard and brittle

0n1 nanopo2ders 48.

-he ultimate tensile stren*th ( #-S ) is the ma:imum stress 2hich a material can

2ithstand in tension. ith the addition o .'2t3 0n1 nano!particle, the mechanical

properties 2ould be a ected. t 2as sho2n in Section 4 ! 8 that the microstructure 2as*enerally re ined 2hen 0n1 nano!particle 2as added. t is oreseen that the tensile

properties 2ill be impro$ed. -he results o tensile tests on SS" lead! ree solder alloy are

sho2n as Fi*. 6. -he tensile stren*ths are impro$ed by 0n1 nano!particle addition but,

the elon*ation to ailure o the solder alloy becomes lo2er. -his may be due to the


12/21

increase in the @uantity o the hard 0n1 particles 4 8. For e:ample, as sho2n in Fi*. 7, the

SS"' ' alloy has #-S o about MPa, 2hen 0n1 nano!particle 2as added the #-S is

increased by appro:imately 3 to become about 9 MPa. ith the addition o 0n1

nano!particle, the elon*ation to ailure is decreased. n particular, it is still comparable

2ith that o the Sn!Pb solder alloy.

t is also be noticed that, the tensile data are *enerally analyzed by relatin* the

steady!state strain rate to the stress throu*h a po2er!la2 relation. -he stress e:ponent RnR

and the acti$ation ener*y (W c) or tensile tests can be calculated rom the Dorn e@uation 4

2here W c represents the acti$ation ener*y or creep, n the po2er!la2 stress

e:ponent, X the temperature!dependent shear modulus, b the +ur*ers $ector, A

a material!dependent constant, / the uni$ersal *as constant and - is the temperature. -he

$alues o n and W c are representati$e o the dominant creep mechanism.

-he tensile beha$ior o the Sn 7' Sb ' alloy has been in$esti*ated by *oshe$ et al.

and they ound that microcrac?s nucleate because o decohesion alon* the matri:Cparticle

boundaries 4 8. -he SnSb and Sn 9"u ' intermetallic particles play t2o di erent roles. -hey

may stren*then the alloy matri: and pre$ent the ormation o lar*e dislocation pile!ups at

*rain boundaries. 1n the other hand, the hi*her number o particles in a *i$en matri:, the

more matri:Cintermetallics inter aces it contains, leadin* to a hi*her li?elihood o microcrac? nucleation that can speed up the ailure process. n 48, 1ne o the ma or

results is con irmin* that the steady!state strain rate o SnSb ' is controlled by the

dislocation!pipe di usion in the Sn matri:.48 -he data o lo2 stress under di erent

temperatures and stresses o SS"' ' and SS"! .'0n1 are presented in Fi*. &&. ith the

addition o the 0n1 nano!particles, the lo2 stress decreased substantially.

'.' )ensile responseA typical set o representati$e stress strain cur$es o the SS"' ' solder and SA" .'0n1

composite solder are sho2n in Fi*. 7 a and b . -he sets o stress strain cur$es o the

solders stretched by a constant strain rate o G.%:& !% s!& at the de ormation temperatures

76, , %6 and G . From these i*ures, it is noted that le$els o the stress strain

cur$es shi ted to2ards hi*her $alues by decreasin* the testin* temperatures. Moreo$er,


13/21

addition o 0n1 is noticed to increase the le$el o the stress strain cur$es at all test

conditions (Strain rate and testin* temperature). n details, stress strain characteristics

namely the ultimate tensile stress #-S , the yield stress y . , racture stress and total

elon*ation o both SS"' ' solder and SS" .'0n1 composite solder are stron*ly

a ected by the $ariation o the testin* temperature and the e:istence o the nano!sized

0n1 particles as e:hibited in i*ure & a!c. For both solders at the constant strain rate,

raisin* the testin* temperature resultin* a continuous so tenin* and lo2er $alues o #-S ,

y and 2ere obser$ed. +ut, the total elon*ation o SS" .'0n1 composite solder 2as

less than that o SS"' ' solder. -he results indicate that, the presence o nano!sized 0n1

particles rein orced the tensile characteristics but also diorites the ductility o SS"' '

solder. o2e$er, ductility decreased because o a lar*e amount o micro!porosity alon*

*rain boundaries and crac? nucleation sites in the orm o hard and brittle 0n1 nano!

po2ders48.

ndeed, the nano!size particles are dispersed uni ormly and homo*eneously

distributed in metal matri: 2hich pro$ide hi*h barrier by impedin* *rain boundary

slidin* and also dislocation mo$ement 4 8. Furthermore, their rein orcement pro$ides

su icient loc?in* o the *rain boundaries to limit *rain boundary *lidin* or slidin* as

result enhance the creep resistance and mechanical characteristics. -his could be

summarized the in luence o the nano!size particles in K (&) pinnin* *rain boundaries and

thus impedin* slidin* o the *rain boundaries, ( ) the increase o dislocation densities and

obstacles to restrict the motion o dislocation and ( ) the dispersion hardenin* mechanism

o the matri: and 0n1 nano!po2ders 48

Accordin* to the a*ner


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ha$e a hi*her lo2 resistance than the matri:, and be un!de ormable and resistant to

racture 4&G8. -hat is, nano!sized particles or ibers are seen as the best candidate as

rein orcement particles.

Fi*ure &


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Fi*ure

-ables summarizes the di raction lines o the phases and d!$alue or SA"! . solder

alloy

$

Arbitrary #nits


16/21

Fi*. a 1M ima*e o (SS"' ')

Fi*. b 1M ima*e o (SS"! .'0n1) at room temperature (& J)

Fi*. % a!b


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Fi*ure 'a> FE!SEM ima*e o SS"' 'Fi*. (%b) EDJ analysis o "u!Sn M"s

Fi*ure 9a> FE!SEM ima*e o SS"' 'Fi*. ('b) EDJ analysis o "u!Sn M"s

Fi*ure Ga> FE!SEM ima*e o SS"' 'Fi*. (Gb) EDJ analysis o "u!Sn M"s


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Fi*ure 6a> FE!SEM ima*e o SS"! .'0n1Fi*. (Gb) EDJ analysis o eutectic re*ion M"s

Fi*. 6 SS"!0n1 as resa$ed


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SS"!0n1

SS"' '


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Fi*ure (7) sho2s the tensile properties o SS"' ' and S"" .'0n1 at di erent

temperatures


21/21

Fi*ure ()

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