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High-Strength Copper Alloy Wires and a Rods - EFTEC-98W,
98BD and 98FC

INTRODUCTION

As electronic devices are becoming smaller, lighter inweight and higher in performance, our company has
been developing leads and connectors for electronicparts, and conductive materials such as welding electrodes, to fulfill various needs. Materials of copper alloy
wires and rods have been requiring higher mechanicalstrengths, higher electrical conductivities and cable sizes
thinner than existing materials.
Our company has commercialized CZ rod and CC rod
as spot welding electrode chips which have superior electrical conductivities, mechanical strengths and heat resistances. In addition, we have commercialized EFTEC-194W
and EFTEC-64W, which have medium electrical conductivities and medium mechanical strengths, targeting theapplications for CPU lead pins, etc.
Figure 1 shows the examples of the application.

relations between the tensile strengths and the electric
conductivities of our existing copper alloys and of thedeveloped alloy wires which are added with highmechanical strength copper alloys.
The EFTEC-98W (wire) shows a good electrical conductivity and a high mechanical strength. Therefore, it
can be used for coil springs. Also, as Figure 2 shows, its
characteristics are equivalent to the beryllium copperalloy. Therefore, it can be easily substituted for a beryllium copper alloy.
10090
Electrical conductivity (%IACS)

1.

CC Wire8060

EFTEC-194W

50

EFTEC-97W

4030

In recent years, requirements for electronic parts especially with high mechanical strengths have been increasing. A beryllium copper alloy (C1720) is well known as agood example of copper alloy with a high mechanicalstrength. However, it is high in price and contains environmentally-unfriendly substances.
Given these factors, we have developed environmentally-friendly and high mechanical strength copper alloys“EFTEC-98” series, which are consisting of Cu-Ni-Sialloys (Colson alloys) with slight additive elements.

2.

HIGH MECHANICAL STRENGTH COPPER ALLOY WIRES AND RODS, “EFTEC-98” SERIESThe EFTEC-98 series are optimal for the parts which
require high mechanical strengths. Figure 2 shows theBerylliumcopper（C1720）

6% phosphor bronze（C5191W）
0200400600
800 1000 1200Tensile strength（MPa）

1400 1600

Figure 2 Relations between tensile strengths and electricalconductivities in wires.
100

TPC90 （C1100W）

Electrical conductivity (%IACS)

Figure 1 Examples of  the application.

EFTEC-98W

Brass (C2700W)

200
CPU lead pin
EFTEC-194W

EFTEC-64W

70

10Welding electrode chips
CZ rod, CC rod

Our developed alloys

TPC（C1100W）

CC Rod80

Our developed alloys

CZ RodCZC Rod70

EFTEC-64BD

60

EFTEC-194BD

50

EFTEC-97BD

40
Free-cutting brass（C3604BD）

30

EFTEC-98BD
EFTEC-98FC

20
100Free-cutting
beryllium copper（C17300）
150 200 250 300 350 400 450
Vickers hardness (Hv)

Free-cutting phosphor bronze（C5441BD）
050

100

Figure 3 Relations between Vickers hardness and electricalconductivities in rods.

Furukawa Review, No. 43

201358

High-Strength Copper Alloy Wires and a Rods - EFTEC-98W, 98BD and 98FC

Figure 3 shows the relations between the Vickers hardness and the electrical conductivities of the rods.
The EFTEC-98BD (rod) is used for shank materials andarm materials of portable spot welding guns which areused for welding automobile bodies and steel furniture.
The EFTEC-98FC is optimal for the connectors which
require high mechanical strengths and cutting performances.
Also, as Table 1 shows, the coefficients of thermal
expansion and the longitudinal elastic moduli of theEFTEC-98 series and the beryllium copper are equivalent.
Therefore, the EFTEC-98 series can be substituted easily
for the beryllium copper alloys.
Figure 4 shows the application examples of highmechanical strength copper alloy materials.
Table 1

Physical characteristics (typical values).

Coefficient
ThermalElectrical Longitudinal
Specificof thermal conductivity conductivityelastic
expansion
modulus Gravity
× 10 -6/K W/（m･K） ％ IACS
GPaEFTEC-98
seriesBerylliumcopperalloy（C1720）

17.8

17.8

120

109〜130

30

125

22127

Table 2

Chemical composition (typical values).
（mass%）

8.8

8.3

ShankArm

Coil spring
EFTEC-98W(C3604BD), free-cutting phosphor bronze (C5441BD) andfree-cutting beryllium copper (C17300) have been used.
However, some of these copper alloys are not good forhuman bodies and the environment because lead isadded.
Given this factor, we have succeeded in developing acopper alloy material EFTEC-98FC which does not contain environmentally-unfriendly substances but has a highmechanical strength and a superior cutting performance.
The EFTEC-98FC is a Cu-Ni-Si based alloy, which issimilarly to the EFTEC-98W and the EFTEC-98BD, andadditive elements are changed in order to meet both ahigh strength and a cutting performance.
The EFTEC-98FC is a copper alloy material in which
sulfides are dispersed in the metal by adding sulfur. The
cutting performance of this alloy is enhanced by controlling the disperse status of the sulfides. Table 2 shows thechemical compositions of the EFTEC-98 series.

Portable welding gun parts
EFTEC-98BD

Connector pins
EFTEC-98FC

NiSiSnZnMg

FeS

EFTEC-98W, BD

3.75

0.9

0.15

0.5

0.1

--EFTEC-98FC

3.75

0.9

0.15

--

0.15

0.15

Actually-used free-cutting beryllium copper disperses
fine lead grains in the metal as chip breakers at cutting
work, and these lead grains finely divide cut material pieces. The mechanism is that metal pieces are divided bylead grains which melted and weakened by the heat generated in the cutting work.
On the other hand, the EFTEC-98FC disperses sulfides
as chip breakers in the metal, thereby divide cut metalmaterials finely. The mechanism of the division: the sulfide grains in the cutting chips induce ductile breaking
caused by the plastic deformation which is brought by thecutting work. Then the cutting chips generate cracks andthe cracks diffuse. Finally, the cutting chips are divided.
Figure 5 shows the shapes of the cutting chips generated in the process of lathe work on the EFTEC-98FC andthe free-cutting beryllium copper alloy. In the general copper alloy, the cutting chips are in irregular spirals. In theEFTEC-98FC and in the free-cutting beryllium copper
alloy, cutting chips are finely divided.

Figure 4 Examples of application of the developed materials.

3.

CHARACTERISTICS OF THE EFTEC98FC WITH A HIGH CUTTING PERFORMANCE

Cutting work such as turning and boring are occasionallydone as the processing methods of copper alloy parts.
For the parts which have highly complicated forms or
require high dimensional accuracies, free-cutting bronze

EFTEC-98FC

Free-cutting beryllium copper alloy

Figure 5 Shapes of cutting chips of the EFTEC-98FC and thefree-cutting beryllium copper alloy.

Furukawa Review, No. 43

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High-Strength Copper Alloy Wires and a Rods - EFTEC-98W, 98BD and 98FC

4.

CONCLUSIONThe EFTEC-98 series can be substituted for the copper
alloy parts in which high price beryllium copper alloys
have been used. They can be supplied at low prices,
thereby contribute to the cost reduction. In addition, theEFTEC-98FC is an optimal copper alloy material for theconnectors, etc. which require automatic operation by NC
machining such as cutting and boring.
Our copper alloy materials have balanced mechanicalstrengths and electrical conductivities. We can provide
the copper alloy materials which best meet your purposes.

For more information, please contact:
Sales Management Division
Metals Company
TEL: +81-3-3286-3833 FAX: +81-3-3286-3289
e-mail: kinzoku@furukawa.co.jp

Furukawa Review, No. 43

201360