Development of a Cu-Ni-Si Copper Alloy Strip
for Narrow Pitch Connectors
Hiroshi Kaneko *, Kiyoshige Hirose *, Koji Sato *, Nobuyuki Tanaka *2,
Hiroaki Kanamori *2, Kuniteru Mihara *3, and Tatsuhiko Eguchi *Connectors for boards and modules are becoming narrower in pitch due tomultipolarization and smaller because electronic devices are becoming
compact and multifunctional. A copper alloy strip used for electric contact materials in thesesmall-sized connectors requires high strength and good performance to bending. Furukawa
Electric improved these two conflicting features under the control of the metal structures: wehave developed a new Cu-Ni-Si alloy (Colson alloy) EFTEC-820 (C64775: Cu-2.3Ni-0.65Si-0.5Zn0.15Sn-0.1Mg-0.15Cr). This paper reports the improved features of this alloy and our grainrefining technology that contributes to achieving these features.

ABSTRACTINTRODUCTION

1.1 Development Background
Connectors for electric devices (mobile phones and notebook PCs) are becoming lower in height and narrower inpitch. The materials used for these connectors require ahigh strength, a good performance to bending and agood plating performance.
The terminals of the connectors for automobile wire harnesses are becoming smaller due to multipolarization. It
is because the numbers of electric devices such as electronic control units (ECUs) and because the amounts ofwiring are increasing. Moreover, the temperature at whichthese connectors are used is becoming higher (such as
in engine compartments). The materials used for in-vehicle terminals require improvements in high strength
together with better performance to bending, and connecting reliability at high temperatures.
We have developed a high-performance copper alloy strip
EFTEC-820 that meets these requirements.
1.2 Features of EFTEC-820
Table 1 shows the chemical composition of EFTEC-820. It isa Cu-Ni-Si alloy where Ni and Si are the major components.
It contains sub additional elements: Zn, Sn, Mg and Cr.
Table 1

Chemical composition of EFTEC-820 (mass%)(Representative value).

Figure 1 shows the relation between the electrical conductivity and the tensile strength of various copper alloys.
Table 2 shows the representative values of EFTEC-820’s
mechanical features. EFTEC-820 is of two types: temper
H and temper EH. EFTEC-820 shows a high strength anda good performance to bending. Table 3 shows the representative values of EFTEC-820’s physical characteristics.
EFTEC-820 shows a 38%IACS electrical conductivity,
therefore EFTEC-820 is suitable not only for signal connectors but also for certain kinds of power connectors.

100Electrical conductivity（%IACS）

1.

TPC

90

C18020（EFTEC-45）
C18045（EFTEC-64T）

80
70
60

C1750050

C64770（EFTEC-97）

40

C17530C17200

20

C5210

10
0
200

Si
0.65

Zn
0.5

Sn
0.15

Mg
0.1

Cr
0.15

Cu
Bal.

C64775（EFTEC-820）
C64790（EFTEC-98Ｓ）

30

300

400

500

C19900

600

700

800

900 1000 1100 1200

Tensile strength（MPa）

Figure 1
Ni
2.3

C14410（EFTEC-3）

The electrical conductivity versus the tensile
strength of EFTEC-820 and other copper alloys.

* Metal Research Center. R&D Div.
*2 Manufacturing Innovation Department, Copper Strip Div.
Metal Company.
*3 Quality Assurance Department, Copper Strip Div. Metal
Company.

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Development of a Cu-Ni-Si Copper Alloy Strip for Narrow Pitch Connectors

Table 2The mechanical features of EFTEC-820(Representative value).
H
790
745
10
245

Tensile strength (MPa)0.2% proof stress (MPa)Elongation (%)
Vickers hardness
Young’s modulus (GPa)Poisson’s ratio
Minimum bendable radius(Bad way, 90°– W bend, w=1 mm)

Table 3

（a）
EH
840
815
7
255
130
0.33

0R

%IACS
W/mK
-6
×10 /°C
3
g/cm

38
157
17.8 (20~300°C)
8.8

Three features of EFTEC-820 and the techniques toachieve them.

Features
1. High strength
2. Good bendability
3. Good reliability

Techniques
Increase in precipitates density
Refinement of grains with Zener-pinning
Improvement in heat resistance and plating
performance

Following chapters show the details of the alloy design
under control of the metal structures and the good characteristics of EFTEC-820.

2.

TEM images of Ni-Si precipitates. ((a) EFTEC-820,(b) Other Cu-Ni-Si alloy that has large precipitates.).

0.7 tR

1.3 The Design of the Alloy of EFTEC-820
Table 4 shows the design overview of EFTEC-820. To
make copper alloys high in strength, hardening by plastic
working processes such as rolling is a general method.
Performance to bending workability deteriorates whensuch a method is applied, and therefore could not meetthe severe demands of recent years. We succeeded in
improving strength and performance to bending by applying a proactive control of two kinds of metal structures:
precipitate structures and grain size.

Table 4100 nm

20 nm

Figure 2

The physical features of EFTEC-820(Representative value).

Electrical conductivity
Thermal conductivity
Coeff. of thermal expansion
Density（b）

HIGH STRENGTHEFTEC-820 is a Cu-Ni-Si copper alloy. Hardening occurs
when Ni-Si compounds finely precipitate. EFTEC-820
densely and finely controls precipitates by applying anappropriate heat-treating process and improves strength.
Figure 2 shows the states of Ni-Si compounds observedby transmission electron microscopy (TEM). (a) (EFTEC820) shows a dense Ashby-Brown contrast that repre1)
sents a coherency strain . The high strength is achieved
when the strain is in lattice. (b) shows the state of a precipitate structure when the tensile strength is about
100 MPa lower with the same composition. It shows larger
precipitates and no dense strain contrast like in (a).

3.

IMPROVEMENT IN BENDING PERFORMANCEThis chapter shows a phenomenon where the crystal
grains are refined by adding Cr into a Cu-Ni-Si alloy.
Effects of bending performance improvement caused by
the phenomenon are also shown.
3.1 Measuring Method
First, alloys in four levels of Cr amounts (Table 5) were
produced in strip forms by hot and cold rolling. Second,recrystallized structures were obtained by a heat treatment solution at a temperature of 1073 K. Using specimens after the heat treatment solution, the average grain
sizes were measured with an optic microscope, and theaverage sizes and volume fractions with a TEM. The components elements of the precipitates were analyzed withan Energy Dispersive X-ray Spectroscopy (EDX).
After that, the precipitates went thorough an age-hardening heat treatment and a cold rolling, then they were
adjusted to about TS=790 MPa which corresponded totemper-H and to about TS=840 MPa which corresponded
to temper-EH.
Table 5alloy namealloy-1
alloy-2
alloy-3
alloy-4

Chemical compositions of specimens (mass%).
Ni
2.30
2.32
2.32
2.32

Si
0.55
0.68
0.68
0.69

Zn
0.50
0.50
0.50
0.50

Sn
0.15
0.15
0.15
0.15

Mg
0.08
0.09
0.08
0.09

Cr
–
0.05
0.10
0.20

Cu
Bal.
Bal.
Bal.
Bal.

The performance to bending was evaluated by a 90°
W-type bend and a 180° closely-attached U-type bend
based on Japan Copper and Brass Association technicalstandard (JCBA-T307 (2007)). The evaluation methods
are shown in Figure 3. In the 90° W-type bend test, thebending was applied at various inner bending radii. After
that, the Minimum Bendable Radius (M.B.R: the minimum
radius which does not cause a crack on the top of thebending part) was divided by the thickness of the specimens, then the result was standardized and used as anindicator of the performance to bending. Also, assuming
various connector designs, the widths of the specimens
were changed in the range 0.25−10 mm, and, theirdependency was studied. At the 180° closely-attachedU-type bend test, the bending was applied without an
inner radius, and, the result was evaluated with the exist-

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Development of a Cu-Ni-Si Copper Alloy Strip for Narrow Pitch Connectors

ence or the nonexistence of a crack on the top of thebending part.
For information purposes, our company’s conventional
Cu-Ni-Si materials (C64770 (EFTEC-97), C52100(8mass%Sn-Cu)) were compared. Table 6 shows chemicalcompositions of the evaluated materials.

(a)

(b)

Observe area

Observe area

w : width

Rolling
directiont : thickness=0.15 mm

Rolloing direction

width=0.5 mm

Inner bend radiusFigure 3

（a）

（b）

（c）

（d）

thickness=0.15 mm

The test method of bendability education. ((a) A
90° W-type bend test, (b) A 180° closely-attachedU-type bend test.).

Chemical compositions of bend test specimens (mass%)(Representative value).

Table 6

Figure 5 shows the precipitate states of the alloy-1−4
after heat treatment solution is observed with a TEM. In all
four alloys, 20−100 nm of the spherical precipitates weredispersed. The more Cr was added, the more was theratio of the volume the precipitates. Figure 5 (a) showssome Ni-Si compounds that did not dissolve when Cr was
not added, but the number of compounds was dominantly small compared to the case when Cr was added.
Figure 6 shows the result of a componential analysis of a
precipitate in the grain boundary. The precipitate was a
Ni-Si-Cr ternary compound.

Ni
C64775 (EFTEC-820)
Former Cu-Ni-Si alloy
C64770 (EFTEC-97)

2.30

C52100

–

Si
0.65
0.55
–

Zn

Sn

Mg

0.5

0.15

0.1

–

8.0

–

Cr
0.15

P
–

–
–

Cu
Bal.

0.1
500 nm25

Average grain size（µm）

TEM images of the specimens solution treated. ((a),(b), (c), (d) indicate alloy-1, -2,- 3,- 4 respectively.).

1000

Cu

900

Cu

800
700
600

Ni

500
400
Si

300
200

20

Cr

100
0
15

Figure 6
10

0
0

0

1

2

3

4

5

6

7

8

9

10

Energy E（KeV）

5

Figure 4

Figure 5

Counts（a.u.）

3.2 Effect of Grain Refinement by the Addition of Cr
Figure 4 shows the relation between the average crystal
grain sizes of heat treated solution materials and theamount of Cr. When Cr was not added, the size of thegrain was about 20 µm . When Cr was added, the size ofthe grains was about 5 µm. That was because the grains
were refined by the addition of Cr. The effect saturated ataround 0.1 mass% of the Cr addition.

0.1
Cr contents（mass%）

0.2

Relation between the average grain sizes and the
Cr content in treated solution specimens.

EDX spectrum of a compound on the crystal grainboundary.

Various test results have been reported and several models have been proposed about Zener-pinning. Zenerpinning is an effect that disperses particles pin grainboundaries. It has been formulated in formula (1), using
the grain size [R ], the average size of a dispersed particle2)[r ] and the volume fraction of a dispersed particle [f ] .

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Development of a Cu-Ni-Si Copper Alloy Strip for Narrow Pitch Connectors

R = β・r / f（ β : 4/3〜4/9）(1)

Figure 7 analyzes the relation between the ratio of theaverage particle size [r ] to the volume fraction [f ] and thegrain size [R ] in alloy-1−4.
A proportional connection existed between r /f and R . Its
proportionality coefficient was about 0.5. Zener-pinningapplied on these Cu-Ni-Si alloys were confirmed. The reason behind the restrictive effect of crystal grain growth isincreased by the addition of Cr is because the Cr compounds that disperse as second phase particles increases even with heat treatment solution that Ni and Si dissolve, thus a high pinning force is obtained.

finely controlled with the addition of Cr, had more shear
bands than in alloy-1. As a result, the effect that deformation volume in each shear band was reduced andrestrained the generation of the cracks.

（a）

（b）

ND

r/f
4/

15

R=0.49・r/f

R=

10

4/

30 µm
RD

r/f
9・

Figure 8

Cross section microstructures in bend specimens.
((a) indicates alloy-1 and (b) indicates alloy-4.
Extended lines of arrows indicate shear bands.).

50

Figure 7

3.3

3・

20

R=

Average grain size（µm）

25

0

10

20

30
r/f（µm）

40

50

Relation between the average grain size and the r/f(r : size of a particle, f : volume fraction.)

Relation Between the Grain Size and the
Performance to Bending

Figure 8 shows the observation of the cross section of theW-bend part in alloy-1 and -4. These alloys were pretreated by a heat treatment solution and an age-hardeningheat treatment. Alloy-1, whose grain size was about
20 µm, had big increases on the surface and small cracks.
On the other hand, alloy-4, whose grain size was controlled to 5 µm, had no crack. Extended lines of arrows
indicated the regions where the changes in the metal
structures were larger than other regions. The regions
between the arrows remained the same after the deformation. The regions that arrows indicate absorbed the mostpart of the entire deformation. These deformed regions
had zonal shapes of about 5 μm width in about 40° direction from the bent surface. They developed through grainboundaries and several grains. Therefore, they were con4)
firmed as shear bands . Minor cracks in the bent surfaceof alloy-1 formed along these shear bands. That is, theprocess of bend cracking in Cu-Ni-Si alloys progresses inthis order: the generation of shear bands, the concentration of the deformation into the shear bands, the destruction caused by the deformation along the shear bands.
On the other hand, alloy-4, whose crystal grains were

The electron back-scattering diffraction (EBSD) method
was used to preliminary quantify the local deformations
above. Figure 9 shows the analysis of the local strains.
The EBSD method measures crystal orientation by diffraction patterns that are obtained when a specimen is irradiated by electron. Continuous information of orientation
distribution can be obtained by scanning electron. For
that reason, the method has been proposed as a way to5), 6). It
analyze microscopic deformation state in a material
is difficult to obtain reliable orientation information in allmeasurement points because a clear diffraction image
cannot be obtained in principle in the area where a material has a high strain. Although, qualitative discussion ispossible, local minute misorientation was used to present
the degree of a local strain. The analysis of a minute misorientation between measurement points with a distanceof 0.1 µm is shown in Figure 9 with a color map. Whenmisorientation was equal to or exceed 15°, it was decided
to be a grain boundary. Black lines are indicating it.
In alloy-1 whose grain size was about 20 µm, about 70%
of its area was a low-strain area (indicated by blue). Highstrain area (indicated by red) grew through crystal grainboundaries in a zonal shape in about 40° direction fromthe surface. On the other hand, in alloy-4 whose grain
size was controlled to about 5 µm, the deformation area
was also in a zonal shape in about 40° direction from thesurface. However, the area fraction indicated by red
decreased and the area that had middle-strain (indicatedby green) increased. Thus semiquantitative analysis using
the EBSD method confirmed that the grain refinement
had an effect of dispersing the shear bands that weregenerated when the bending deformation occurred.

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Development of a Cu-Ni-Si Copper Alloy Strip for Narrow Pitch Connectors■Procedure of measuring local minute misorientation in crystal grains

Cross section of the bend part断面②Misorientation between neighboringmeasurement points is analyzed.

scan grid
step=0.1 µm

1.2
1.2
0.9°
0.9°
Grain boundary
（>15°
）

1.1°
1.4° 1.1°
1.4°

Local misorientation=（1.2+0.9+1.1+1.4）/4=1.2（deg/0.1 µm）③Results are mapped depending on the diﬀerence of thelocal misorientation

Color

Misorientation（deg/0.1 mm）
0‒ 1
1‒ 2
2‒ 3
3‒ 4
4<

※Black indicates the measurement point
where analysis was impossible becauseof the high local strain

4
Bendability（M.B.R./t）[Bad way]

①Orientation of atomic planes are measured witha distance of 0.1 µ m.

EFTEC-820
Former Cu-Ni-Si alloy（C64770）
C52100

3

ESH
SH

2
EH
1

EH
0
650

700

EH
H
750
800
Tensile strength（MPa）

H

850

900

Figure 10 Relation between the bendability and the tensile
strength.

■Measurement results of the local misorientation
alloy-1（0 Cr）, GS=19 µm, TS=735 MPa

10 µm
alloy-4（0.20 Cr）, GS=4.4µm, TS=747 MPa

Figure 11 shows the marginal bend radius when widths of
specimens were changed in the W-type bend test. EFTEC820 (H) showed extremely good performance to bending
without a crack when the widths of the specimens were in
the range of 0.25–10 mm. In EFTEC-820 (EH), the narrower
widths of specimens had the smaller marginal bend radii.
When specimens were equal to or less than 1 mm in width,
the bending with no crack was possible with 1 t in inner
radius. On the other hand, C52100’s marginal bend radius
was 2 t even with 1 mm in width.
Thus, EFTEC-820 had a high strength and also could bebent without any crack under a severe bend radius equal
to or less than 1 t. It showed superior characteristics to thephosphorus bronze alloy which is universally used forcontact materials.

0%
alloy-1

Area fraction
20% 40% 60% 80% 100%

GS=19 µm

alloy-4 GS=4.4 µm

Figure 9

Analysis of cross section microstructures on bend
specimens by kernel average misorientation (KAM).

3.4 Performance to Bending of EFTEC-820
3.4.1 W-type 90° Bend Test
Figure 10 shows the relation between the performance tobending and the tensile strength. The tensile strength of
EFTEC-820 was 50 MPa higher than that of the C64770(an existent Cu-Ni-Si alloy) and that of C52100 (a phosphor bronze system alloy) when compared under thesame bendability level.

Bendability（M B. R. /t）[Bad way]

10 µm

5

1.7

3.3

w/t
6.7

13.3

66.7

EFTEC-820（H）YS=745 MPa
4

EFTEC-820（EH）YS=815 MPa
C52100（ESH）YS=763 MPa

3
2
1
0
0.1

1.0
Width of specimen（mm）

10.0

Figure 11 The relation between the widths of the specimens andthe standardized marginal bend radius in a bend test.

3.4.2 The U-type 180° bend test
Figure 12 shows the observation results of the cross section of the top of the bending part after the U-type tightlyattached 180° bend test. (a) indicates that EFTEC-820
generated no crack at the bend part. On the other hand, aconventional Cu-Ni-Si alloy could not resist severe stress,
therefore a crack of a few dozens of micrometer in depth
was generated as indicated by the arrow in (b).

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Development of a Cu-Ni-Si Copper Alloy Strip for Narrow Pitch Connectors

50 µm（b）

（a）

50 µm

Sn and Mg addition caused good stress relaxation resistance of EFTEC-820.

Figure 12 Cross section of the U-type bend specimens.
((a): EFTEC-820 (H), (b): Our company’s conventional
Cu-Ni-Si alloy (C64770). An arrow in (b) indicates a crack).

As above, EFTEC-820 was confirmed to show good performance to bending even under severe bending liketightly-attached U-type 180° bend.

4.

RELIABILITY

Copper alloys are subjected to multiple stresses of thermal stress and mechanical stress when they are used forelectric contact materials in connectors. In that case,occasionally lowering the contact pressure occurs iscaused by a creep phenomenon of the materials. The
thermal stresses are sometimes causing a lowering of theplating adhesion in the plated materials. When Au or Ni
plating is unsatisfactory by non-uniformity in base materials, occasionally chemical stress are causing partial corrosion in them. EFTEC-820’s design considers the threecauses of liability degradation that are described above.
This chapter shows evaluations of these three causes.
4.1 Anti Stress Relaxation
4.1.1 Measuring Method
Figure 13 shows the measuring method of the stressrelaxation rate. First, the specimens were loaded 80% of
0.2% yield strength with a cantilever beam method, andkept at 120–170° for 1000 hours (This method is basedon Japan Copper and Brass Association technical standard (JCBA-T309 (2004)). Second, they were unloaded.
Third, the stress relaxation rates were measured fromresidual plastic deformations.
UnloadedStress with 80%-YS
Specimenh0Specimenh1

Heat at 120 ‑170℃
for 1000 hours
Stress relaxation rate（%）=h1/h0×100

Figure 13 Measuring method of stress relaxation rate.

4.1.2 Result
Figure 14 shows the measurement results of the stressrelaxation rate. They showed higher relaxation rates when
the temperatures were higher. In particular, at 150 and
170°C, the stress relaxation rates were equal to or exceed
30 % in C52100. It caused significant lowering of the contact pressure from initial stress. On the other hand,
EFTEC-820 had a low stress relaxation rate at these temperatures and showed a high reliability. A little amount ofStress relaxation rate（％）

70

EFTEC-820
C52100（EH）

60
50
40
30
20
10
0
100

120

140
160
180
Holding tmperature（℃）

200

Figure 14 Relation between stress relaxation rate andholding temperature.

4.2 Characteristics of Sn Plated Materials
4.2.1 Measuring Method
Figure 15 shows the measuring method of the heat resistance of reflow-Sn plating. First, EFTEC-820 (H) initiallyplated with reflow-Sn was bent at 90°. Second, it was kept
at 100−160°C for 120 hours. Third, it was bent back andhad a peeling test with an adhesive tape. Observation of
the adhesive tape that had been peeled and the overview
of the specimen confirmed the existence or the nonexistence of the peeling of the Sn plating.

Bend

Heat at
100 ‑160℃
for 120 hours

Adhesion tape
Bend backPeeling test

Figure 15 Measuring method of the heat resistance ofthe reflow-Sn plating.

4.2.2 Result
Table 7 and Figure 16 show the measuring results.
EFTEC-820 showed good heat resistance because it had
no peeling of the plating at all temperatures (100−160°C).
On the other hand, other Cu-Ni-Si alloy that had low heat
resistance of the Sn plating had peeling of the Sn plating
beginning from the top of the bend part.
Generation of Kirkendall voids is one of the reasons of thepeeling of the Sn plating. Zn that is a sub addition element of the EFTEC-820 restrained it. In addition, it optimized the surface state of the base material and advanced
the heat resistance of the Sn plating.
Table 7

Result of the heat resistance adhesion test on the
reflow-Sn plating.

Holding temperature (°C)
100°C
120°C
140°C
EFTEC-820◦◦◦
Other Cu-Ni-Si alloy
××◦◦: The Peeling of Sn-plating did not occur × : occurred

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◦
×

2010

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Development of a Cu-Ni-Si Copper Alloy Strip for Narrow Pitch Connectors

Tape

5.

Specimen

EFTEC-820
Other Cu-Ni-Si alloy

Figure 16 Result of the heat peeling test on the reflow-Sn plating
at 140°C.

4.3 Au/Ni Plating
4.3.1 Measuring Method
First, specimens were pretreated with diluted sulfuric acid.
Second, they were plated with Ni 1 µm thick, then platedwith Au 0.1 µm thick. After that, the following environmental tests ((1)−(3)) were performed. The study of the effectof the corrosion was performed by measuring the contact
resistance of the surfaces.
(1)Sulfidizing test
H 2S density: 3 ppm Holding temperature: 40°C
Holding time: 24 h Humidity: 70% RH(2)Mixed gas test
H2S density: 100 ppb NO2 density: 200 ppb
Cl2 density: 200 ppb
Holding temperature: 30°C Holding time: 24 h
Humidity: 70% RH(3)Salt water spraying test (ISO9227)
NaCl density: 5% Holding temperature: 35°C
Holding time: 24 h, 96 h
4.3.2 Result
Figure 17 shows the contact resistance values after theenvironmental tests. EFTEC-820 showed no significant
rise in the contact resistance. No corrosion in the basematerial by plating was observed. On the other hand,
C19900, which was a comparative material, showed significant rise in the contact resistance after a mixed gas
test and a salt water spraying test. Green corroded products of the copper were observed on them. That was
because pinholes were generated by the inadequacy ofthe plating uniformity, thus the base material corroded.
EFTEC-820
C19900（Cu-Ti）

Before（1）Sulﬁdation 24hour（2）Mixed gass 24hour（3-1）Salt spray 24hour（3-2）Salt spray 96hour
1

10

100

1000

Contact resistance（mΩ）

Figure 17 The contact resistance after the environmental tests.

CONCLUSION(1) When Cu-Ni-Si alloy was added in minute amount of
Cr, Zener-pinning effect appeared caused by thedisperse of the Cr compounds. It enabled the effective refinement of grains.
(2) The performance to bending was improved by thegrain refinement. The observation of the microstructures and the analysis by EBSD method showed
shear bands that caused cracks when bending
deformations occurred were dispersed.
(3) The EFTEC-820’s stress relaxation resistance, theheat resistance of the reflow-Sn plating and the Au/
Ni plating performance were satisfactory.
The EFTEC-820 (a Cu-Ni-Si alloy (Colson Alloy)) that has
both a high strength and a satisfactory performance tobending was developed by proactively controlling the
precipitates and the grain sizes. It is optimal for B-to-B
type and FPC type connectors that are becoming smaller
because it has a high strength of about 800 MPa and asatisfactory performance to bending at the same time.
The EFTEC-820 is also suitable for in-car small sized terminals because it has a good stress relaxation resistanceand a heating resistance of the Sn plating.
Moreover, EFTEC-820’s high strength and good performance to bending contribute to the thinning of the copper
alloy contact materials for connectors. Natural resourcesaving and cost-cutting can be possible by using EFTEC820 instead of existing copper alloys.

REFERENCES(1) MF Ashby and LM Brown, “Diffraction contrast from sphericallysymmetrical coherency strains”, Phil. Mag. B, p1083 1103, (1963)(2) I. Ohnuma and K. Ishida, “Fundamentals and Applications ofPrecipitation in Steels”, The Iron and Steel Institute of Japan, p. 103
115 (Oct., 2001).
(3) Hiroshi Kaneko, Kiyoshige Hirose, Tatsuhiko Eguchi and Nobuyuki
Tanaka, “Effect of Microstructure on the Bendability of Cu-Ni-Si
Alloy”, Journal of the JRICu, vol.48, No.1, 61 65 (2009)(4) K. Kawasaki and M. Matsuo, “Deformation Structures as Nucleation
Sites for Recrystallization”, Tetsu-to-Hagane, ISIJ, vol. 80, No. 15 p.
1808 1815 (1984).
(5) A. J. Wilkinson and D. J. Dingley, “Quantitative Deformation Studies
Using Electron Back Scatter Patterns”, Acta metal. mater., vol. 39,
no. 12, pp. 3047 3055 (1991)(6) Angus J. Wilkinson, “A New Method For Determining Small misorientations From Electron Back Scatter Diffraction Patterns”, Scripta
mater. Vol. 44, No. 10, p2379 2385 (2001)(7) T. Usami and T. Hirai, “Copper alloy material for parts of electronicand electric machinery and tools” in: US patent, 7,172,662 B2 (Feb.
2007).
(8) Hiroshi Kaneko, Kiyoshige Hirose, Nobuyuki Tanaka and Tatsuhiko
Eguchi, “High Strength and Good Bendability Copper Alloy C64775(EFTEC-820) for Terminals and Connectors”, Proceedings of the58th IWCS/IICIT, International Wire & Cable Symposium (2009)351 357

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