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High Conductivity Copper Alloy for Lead-Frame “EFTEC-45”

In recent years of so-called IT revolution, cellular phones
and network equipment are making dramatic progress.
Copper alloys for lead-frames are used in the semiconductor packages for these electronic equipment, and it isrequired that, for low pin-count packages such as dual
inline package (DIP), small outline package (SOP) anddiscrete devices, they have well-balanced characteristics
in terms of strength and electrical conductivity.
Figure 1 shows the TS-EC diagram of copper alloys forlead-frames where the horizontal and vertical axes represent the tensile strength and electrical conductivity,respectively. EFTEC-45 is located in the middle ofEFTEC-3 and -64T, both being Furukawa Electric's products, so that it is a well-balanced alloy with respect tostrength and electrical conductivity. In terms of alloy components, it belongs to the Cu-Cr-Sn-Zn system, the same
as for EFTEC-64T that has an excellent track record inhigh pin-count packages such as quad flat package(QFP). Therefore, leading-edge technologies acquired by
EFTEC-64T have been applied to achieve not only basic
characteristics required for lead-frame materials but also
excellent surface performance and high reliability.
Table 1 shows the standard specifications. Two types oftemper, 1/2H and H, have been specified to allow suitableselections depending on applications. Table 2 shows thebending workability evaluated under the conditions ofsample width = 10 mm and the W-shaped bending with an
bending angle of 90°. The minimum bending radius of
EFTEC-45 represented by R/t (R for radius and t for thickness) is zero, demonstrating superior bending workability.

Figure 2 shows the isothermal softening curve of H-temper of EFTEC-45 representing the changes in the Vickers
hardness when the material is heated up to five minutes at
450°C and 500°C. EFTEC-45 is seen to have sufficientheat resistance at these high-temperature environments.
Thus, the material characteristics are not damaged byhigh-temperature heating even at the time of wire bonding, thereby maintaining excellent performance. It is also
suitable for Pb-free soldering processes of recent years.

Table 1Temper
Properties
1/2HH

Tensile strengthMPa

360~440400~480

0.2 % yield strengthMPa

330~410390~470

Elongation%≥ 10≥5HardnessHv

115~135

120~145

Electrical conductivity%IACS≥ 77≥ 77

Table 2Bending workability. (Width = 10 mm)
Allowable bending radius (R/t)

AlloysTemper
Good Way

Bad Way

1/2H

00

H

00

H

00.6

EFTEC-45
C194

110

150
TPC, OFC

140

100

Vickers hardness

Electrical conductivity (%IACS)

Standard specifications.

EFTEC-390
EFTEC-45 (1/2H)

EFTEC-45 (H)80
EFTEC-64T (1/2H)
70

50300

120
110
100

EFTEC series

C194 (H)

60

130

450°C
500°C

90Other alloys

80350

400

450

500

550

600050Tensile strength (MPa)Figure 1

TS-EC diagram of copper alloys for lead-frames.

100

150200250300

Heating time (s)Figure 2

Isothermal softening curve.

Furukawa Review, No. 23

2003

126

High Conductivity Copper Alloy for Lead-Frame “EFTEC-45”

Table 3Ag platability.
Heating temperature (°C)

Pre-treatment

EFTEC-45

EFTEC-64T

350

400450with etching

no blisterno blisterno blister

without etching

no blisterno blisterno blisterwith etching

no blisterno blisterno blister

without etching

no blisterno blisterno blister

WireTensile testSolderHeating (150°C)

Joint(failure)SampleFigure 3

Testing method for solder joint strength.

Solder joint strength (MPa)18EFTEC-45
EFTEC-64T
C194

16141210864200200

400

600

800

1000

1200

EFTEC-45 is superior in surface performance, a crucial
characteristic for lead-frame materials. Table 3 shows theresults of Ag platability tests, in which the number of blisters after a 10-minute heating at temperatures of 350,
400, and 450°C is used for the evaluation. No blisters
occurred due to Ag plating under all the conditions,demonstrating excellent Ag platability. Moreover, blisters
do not occur when the surface is etched in pre-treatment
for plating, negating the influences of plating method.
For semiconductor equipment, it is essential to assure
the reliability of solder bonding with substrates. Figure 3
shows the testing method for solder joint strength, andFigure 4 the results, where the tests are carried out up to
1000 hours at 150°C using eutectic solder. EFTEC-45 isseen to have sufficient joint strength after a holding time of1000 hours, confirming enhanced soldering reliability
when used in semiconductor equipment.
EFTEC-45 has satisfactory characteristics in terms of
the adhesiveness with oxides, solderability, resolderability(solder wettability of solder plating after aging), and stresscorrosion cracking, demonstrating such well-balanced
characteristics as for EFTEC-64T.
As described above, EFTEC-45 is especially suitable asa lead-frame material for low pin-count packages, being
superior in cost effectiveness also. Moreover, it is applicable to other uses such as connectors and relays.
For more information, please contact:
Metals Marketing Department, Metals GroupTEL: +81-3286-3850FAX: +81-3286-3663

Heating time (hour)

Figure 4

Solder joint strength.

Furukawa Review, No. 23

2003127