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High-Performance Copper Alloy Wire “C194W”

In semiconductor industry of today, a number of multi-pin
packages such as chip carrier and pin grid array (PGA)
have been developed aiming at improving device integration as well as surface mounting density. With regard totheir lead pins, Kovar (Fe-26%Ni-17%Co) or 42 alloy (Fe42%Ni) wires are widely used in PGAs. Quite a number ofpins are used --sometimes more than 400 pins per package, so that, as the need for high-density integration arises and from the standpoint of heat dissipation and speed
improvement, there is a strong demand for materials ofhigh heat conductivity or enhanced heat dissipation toreplace Kovar and 42 alloy.
C194W is a Cu-Fe alloy with chemical compositions asshown in Table 1, and is equivalent to the CDA19400
alloy specified by the Copper Development Association(CDA). The CDA19400 alloy is a copper alloy with a considerable track record as a sheet material mainly for leadframes. Furukawa Electric has applied its proprietary manufacturing processes to this copper alloy, and throughminute formation of coherent γ -Fe precipitates as shownin Figure 1, succeeded in developing a new wire materialof excellent functionality in terms of strength, electricalconductivity, and durability against multiple bend fatigue.
With respect to electrical conductivity, the materialachieves a conductivity of 65 % IACS or higher, in compliance with CDA19400.
Table 1

Chemical composition of C194W. (mass%)

FeZnP

Cu

2.1~2.6

0.05~0.20

0.015~0.15> 97

Table 2 shows the physical properties of C194W andKovar. C194W is superior to Kovar with respect to electrical and thermal conductivities by a factor of 15 or more,
and is thus advantageous in upgrading IC's heat dissipation and operation speed.
Figure 2 shows the property correlation diagram ofC194W and other selected copper alloy wires together
with Kovar. When compared with Kovar having an equivalent level of strength, C194W is seen to be far superior inelectrical conductivity. Compared with phosphor bronze
wire and beryllium wire (10 •11 alloy), C194W is, although
it has less strength, superior to these materials in terms ofelectrical conductivity, making replacement to C194W
attractive for applications where high conductivity isrequired.

Table 2

Physical properties of C194W and Kovar.
C194W

Kovar°C

1090

1450

Thermal expansion coefficient

10–6/°C

17.4

11.5

Thermal conductivity

W/m • K260

16.8

Electrical conductivity

%IACS

654

Longitudinal modulus of elasticity

GPa

121

137

Density

g/cm3

8.9

8.3

Melting temperature

100

Electrical conductivity (%IACS)

TPC

80

C194W
1/2H60H

EH
Beryllium
copper alloys(10 •11 alloy)
(HT)

1.5S

40

Bs

20

6% phosphor bronze
Kovar

0010nmFigure 1

TEM bright field image of C194W.

200400600

800

1000

Tensile strength (MPa)Figure 2Relationship between electrical conductivity andtensile strength of major wire materials.

Furukawa Review, No. 23

2003128

High-Performance Copper Alloy Wire “C194W”

Table 3Standard specifications of C194W.

TemperTensile strength

MPa

EH

410~480455~520≥ 520%≤5≤2—Vickers hardness

Hv

125~148

135~155≥ 150%IACS

≥ 65

≥ 65

≥ 60

100µm

Table 4HElongation

Electrical conductivity

Figure 3

1/2H

SEM image of bent sample.

Typical product sizes and dimensional tolerance ofC194W.
Wire diameter (mm)Dimensional tolerance (mm)0.2~0.99±0.01

Round wire

1.0~2.99±0.02

3.0~4.0±0.03

Square wire

0.35~1.15±0.05

Table 3 shows the standard specifications of C194W,
where three tempers are available: 1/2H, H, and EH. The
half-softening temperature for the H temper is 320°C or
higher, thereby ensuring sufficient heat resistance in practical applications.
Figure 3 shows the SEM image of a bent sample ofC194W (H temper, φ 0.45 mm) with bending conditions of :90° W bend with a bending radius of R = 0 (R/d = 0,
where d is wire diameter). No cracking occurred demonstrating excellent bending formability.
Table 4 shows typical product sizes of C194W. Wireswith a diameter between 0.2 mm and 4.0 mm are available. Moreover, not only round wires but also squarewires are available, the selected cross section of which isshown in Figure 4. In addition, plated wires are also available.
Currently, C194W is widely used as PGA lead pins for
personal computers, and square wires with reflow tin plating have been adopted in connector terminals for automobiles.
For more information, please contact:
First Marketing Dept., Metals GroupTEL: +81-3-3586-3850
FAX: +81-3-3586-3663

200µma) Round wire

Figure 4b) Square wire

Cross sectional views of C194W.

Furukawa Review, No. 232003129