Furukawa ElectricNewNew Products
Products

Development of High-Performance Copper Alloy
Wires and Rods

INTRODUCTION

With recent reduction in the size and weight of electronicequipment, and improvements in its performance, theelectronic components used have also become smaller
while delivering higher performance. The requirements
imposed on the wire and rod stock materials used for theleads, connectors and other conducting portions of theelectronic components have also increased, and to prevent any deficit in strength or electrical conductivity
caused by smaller diameters and thinner stock, there is aneed for materials having greater strength and conductivity than those currently in use. Accordingly Furukawa
Electric has brought out products made from EFTEC-194
and EFTEC-64 wires (W) and rods (BD) that specificallyemphasize conductivity to target lead pin and similar
applications, and products made from EFTEC-97 and -98
wires and rods that specifically emphasize strength to target connector and similar applications.
Figure 1 shows the relationship between tensile strengthand electrical conductivity for wires, and Figure 2 shows
the relationship between Vickers hardness and electricalconductivity for rods. Compared to the copper, brass andphosphor bronze that have been used up till now, thealloys developed here exhibit an excellent balance
between strength and conductivity.

Table 1 shows the chemical composition of selectedalloys (typical values), and Table 2 shows the physicalproperties (typical values for electrical conductivity andthermal conductivity). None of the alloys contains any Pb,Hg, Cd, Be or other harmful elements, and can therefore
be used with confidence.

10090

Electrical conductivity (%IACS)

1.

Proprietary
Furukawa alloys

CC rod80EFTEC- 64BD

70
EFTEC-194BD

60
50

EFTEC- 97BD

40
Free-cutting brass(C3604BD)

30

EFTEC-98BD

20
100

Free-cutting copper
beryllium alloy(C17300)

Free-cutting phosphor bronze(C5441BD)

0100

200

300

400500Vickers hardness

Figure 2

Relationship between Vickers hardness and electricalconductivity for rods.

Table 1

Chemical composition of selected alloys. (mass %)100

Electrical conductivity (%IACS)

Proprietary
Furukawa alloys

TPC (C1100W)

90

CC wire80
70

EFTEC-64W

60

EFTEC-194W

EFTEC-194:

Cu-2.4Fe-0.13Zn-0.04P

EFTEC- 64:

Cu-0.3Cr-0.25Sn-0.2Zn

EFTEC- 97:

Cu-2.3Ni-0.55Si-0.15Sn-0.5Zn-0.1Mg

EFTEC- 98:

Cu-3.75Ni-0.9Si-0.15Sn-0.5Zn-0.1Mg

50
EFTEC-97W

40

Table 230
20Phosphor bronze(C5191W)

100

Copper beryllium alloy(C1720W)

Brass (C2700W)

0200

400

600

800

1000

1200

1400 1600

Tensile strength (MPa)Figure 1

Coefficient ofThermalElectricalthermal expansion conductivity conductivity-6×10 /°C
W/ (m・K)%IACS

EFTEC-98W

Kovar

Relationship between tensile strength and electricalconductivity for wires.

Physical properties of selected alloys.
Modulus ofelasticity
GPaDensity
g/cm3

EFTEC-194

17.4

260

65

121

8.8

EFTEC-64

17.3

280

70

119

8.9

EFTEC-97

17.8

160

40125

8.8

EFTEC-98

17.8

140

35

125

8.8

Kovar (Ref.)

11.5

16.8

4137

8.3

C1720 W (Ref.)

17.8

109

23

127

8.3

Furukawa Review, No. 32

200792

Development of High-Performance Copper Alloy Wires and Rods

EFTEC-194W/BD AND EFTEC-64W/BD
HIGH-CONDUCTIVITY COPPER ALLOYSEFTEC-194W is used for the lead pins of the pin gridarrays (PGAs) in personal computer CPUs. Formerly thesePGA pins have used iron-based alloys like Kovar (Fe-26%Ni-17 %Co) or 42 alloy (Fe-42 %Ni), but to dissipate theheat generated by larger scales of CPU integration andhigher operating speeds there is a need for materials thathave higher thermal conductivity without compromisingstrength. We have developed products that meet thatneed. This alloy, as shown in Table 1, is a Cu-Fe based
alloy, and is the CDA19400 alloy, which meets the global
standard established by the Copper Development
Association (CDA). CDA19400 is a copper alloy with asolid track record for lead frames and other strip products,
but with our development of proprietary manufacturing
processes to control the size and density of precipitates it
was superior in electrical conductivity, that is to say thermal conductivity, and exhibited superior strength, andspecifically the repetitive bending workability required for
PGA pins. Figure 1 and Table 2 also show the characteristics for the Kovar alloy used in the past, and we can saythat EFTEC-194W, while equivalent to Kovar in terms oftensile strength, represented a more than 15-fold improvement in electrical and thermal conductivity, making it
extremely advantageous for PGA pin applications.
EFTEC-64 is one of our company’s proprietary copper
alloys, and has an extremely good track record as a leadmaterial for QFPs and QFNs. Since it outperforms EFTEC194W/BD in strength and electrical conductivity, it is amaterial for which we can look forward to developing
applications as lead pins, terminal components and solidstate components.
All of these materials exhibit good header machinability
and cold forgeability, and can be formed into a wide variety of shapes.

3.

Low-temperature annealed EFTEC-97W shows a similarlevel of stress relaxation resistance to age-hardened
C1720W, and low-temperature annealed EFTEC-98W has
properties superior to C1720W. This shows that EFTEC97W and -98W undergo little change in spring pressure
over time, and therefore provide high reliability in spring
applications.

4.

CONCLUSIONS

Figure 4 shows examples of products using EFTEC194W, EFTEC-97BD and EFTEC-98BD. EFTEC-97BDand -98BD show outstanding machinability, and are well
suited for use in coaxial connectors, contact pins, etc., asa replacement for free-cutting phosphor bronze (C5441)
or free-cutting copper beryllium (C17300).
For more information, please contact:
No. 2 Sales Dept., Metals Co., Furukawa Electric		 TEL: +81-3-3286-3831 FAX: +81-3-3286-3663

10090

Stress relaxation (%)

2.

80

EFTEC-97W

EFTEC-97W low-temperature annealed stock

EFTEC-98W

EFTEC-98W low-temperature annealed stock

C1720W

C1720W age-hardened

Phosphor bronze C5191W

65/35 brass C2700W

706050403020
1000100

200300

400

500

600

Heat treatment time (h)Figure 3

Stress relaxation resistance.

EFTEC-97W/BD AND -98W/BD HIGHSTRENGTH COPPER ALLOYSEFTEC-97 and -98 are our company’s proprietary alloys
consisting of a Corson (Cu-Ni-Si) alloy base with theaddition of trace elements (Zn, Sn and Mg). In addition tohigh strength and high electrical conductivity, they exhibit
superior resistance to heat and stress relaxation, platability and solder adhesion properties. This makes a significant contribution to raising the reliability of electronic
components. As Figure 1 shows, EFTEC-98 wire (W) provides high strength verging on that of copper beryllium(C1720), and since, as shown in Table 2, EFTEC-98 andC1720W are equivalent in terms of coefficient of thermal
expansion and modulus of elasticity, it can be considered
as a replacement for C1720. EFTEC-97W/BD is inferior toEFTEC-98 in strength, but its electrical conductivity ishigher, making it highly suitable for applications in whichelectrical and thermal conductivity is important.
Figure 3 shows the strength relaxation resistance (testtemperature: 150°C, load stress: yield strength x 0.8).

(a) Use of EFTEC-194W in CPU pins.

(b) Use of EFTEC-97BD and -98BD in coaxial connectors.
Figure 4

Representative applications.

Furukawa Review, No. 32

200793