Furukawa Electric, Furukawa Circuit Foil, Furukawa Techno Material

Electronics-Related Metal Products of Furukawa Electric Groupby Yoshimasa Ohoyama *, Shinji Tagami *, Masaaki Kurihara *,Isao Takahashi *2, Tadao Nakaoka *3 and Tetsushi Habu *4

As the IT industry reaches new heights of prosperity in recent years, the electronics markets in such areas as digital home appliances and mobile equipment continue to grow, together with the automotive onboard equipment market spurred by automotive
electronics. Accordingly, the Metals Company of Furukawa Electric in conjunction with othergroup companies, with their business mainstays founded on copper and copper alloy strips,
functional surface-treated products, wires and bars, copper foil products and special metal
products, are focusing on the technology and product development of raw materials and components targeted at the electronics markets. We intend to expand our production capacity andsales amount by establishing a suitable system for these strategic products.

ABSTRACTINTRODUCTION

As the IT industry reaches new heights of prosperity inrecent years, the electronics markets in such areas asdigital home appliances and mobile equipment continue
to grow, together with the automotive onboard equipment
market spurred by automotive electronics. Accordingly,
the Metals Company of Furukawa Electric in conjunction
with other group companies, with their business mainstays founded on copper and copper alloy strips, functional surface-treated products, wires and bars, copper
foil products and special metal products, are focusing on
the technology and product development of raw materials
and components targeted at the electronics markets. The
characteristics and technology involved with the representative products in these business fields will be presented in this paper.

2.

STRIP PRODUCTS

Main strip products for electronics-related fields include
copper alloys for leadframes and those for connectors.
While the Metals Company focused on the developmentof leadframe copper alloys until the middle of the 1990s,
the focus has been shifted to the development of connector copper alloys in the early 2000s.
As the electronic equipment have reduced in size andweight in recent years, ICs and connectors used in these* Technical & Engineering Dept., Metals Co., Furukawa Electric*2 2nd Dept., Metals Research Center, R&D Div., Furukawa
Electric*3 Furukawa Circuit Foil
*4 Engineering Dept., Special Metals Div., Furukawa Techno
Material

equipment have become smaller in size, lower in heightand narrower in pitch. This trend has been clearly reflected in the performance requirements for the raw materials,
resulting in a more demanding requirement in terms ofstrength, electrical conductivity and workability. High-performance copper alloys developed in response to themarket needs will be described below.
2.1 Copper Alloy for Leadframes
Figure 1 shows the forecast quantity of semiconductor
devices production issued by Electronic Trend Publication
Inc. in 2005. It can be seen that, whereas packages that
do not use leadframe represented by BGA and WLP show
a strong growth, non-lead type packages such as DFN
and QFN, among those that use leadframe, display a very
steep growth trajectory. Conventional QFP shows asteady increase as well. Since EFTEC-64T, one of our

Package production number (million pieces)1.

180000160000PKG Forecast by ETP 2005
DCA
WLP
FBGA
BGA
PGA
QFN
QFP
CC
DFN
TSOP
SO
SOT
DIP

140000120000100000
80000
60000
40000
20000

Figure 1

0

2004

2005

2006

2007

2008

2009

Year

Forecast of IC package production by package family.

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Electronics-Related Metal Products of Furukawa Electric Group

main products, has a large share in the QFP and QFN
markets, it is expected that the demand for the alloy willgrow in the future also.
Figure 2 shows the relationship between hardness andelectrical conductivity of various copper alloys for leadframe. In the figure the alloys in red are Furukawa
Electric’s developments.
1) EFTEC-64T and EFTEC-64T-C
These Cu-Cr-Sn-Zn system alloys are characterized bymedium strength and high electrical conductivity (seeFigure 2). Due to their well-balanced properties, they
maintain a close to 40 % share in the QFP market, thus
being recognized as one of the de facto standards forleadframe stocks. They offer not only medium strengthand high electrical conductivity, but also superior mounting reliability such as electro-platability, oxide film adhesion and solderability, and thus are applicable to a varietyof packages.
Moreover, they would not curl during the leadframe production process of QFN even if half etching is heavily
used, since the residual stress in the material is reducedby means of a proprietary manufacturing technology.
Furthermore, in the dicing process to cut the molding
resin, they exhibit cutting property far superior to otheralloys.

100
90

Electrical Conductivity
(

80

TPC

EFTEC-64T, 64T-C
Alloy 19460

EFTEC-7025

50
40

MF202

30
20

0

EFTEC-23Z

Alloy 42
50

Table 1100

150

Peeling temperature ofoxide film
（℃）

Kovar

200

250

Furukawa

A
company

BcompanyCcompany

370

300

340

360

300

Vickers Hardness

Relationship between Vickers hardness and electricalconductivity of various copper alloys for leadframe.

50000

Sales of connectors (million $)Figure 2

Adhesiveness of oxide film.

KLF125CAC92

102) EFTEC-7025 (C7025)
We have entered into the market for C7025, a de facto
standard in the leadframe industry, after establishing its
production system.
EFTEC-7025 is characterized by its top-ranked strength
as for leadframe stocks, as well as by its medium electrical conductivity (see Figure 2). This alloy is mainly usedin extra-high pin count packages such as QFP.
The development program was targeted at improving
the disadvantages of conventional products. More specifically, we have made efforts to, and succeeded in, achieving the optimum performance balance in terms of expansion and contraction property at stamping, Ag electroplatability and adhesion property of oxide film. Table 1
shows the results of evaluation of oxide film adhesion
characteristics. Good adhesion properties can be seen
when compared with other materials.
2.2 Copper Alloy for Connectors
With the growing demand for digital home appliances
including mobile phones, digital cameras, LCD TVs, DVDrecorders and game machines, the connector market for

KFC

EFTEC-3
EFTEC-45

70

EFTEC-64T-C has a small amount of Si added to thecomposition of EFTEC-64T, achieving an improvement in
the disadvantageous stamping formability of EFTEC-64T
while preserving the fundamental property of EFTEC-64T.
By utilizing our proprietary technology for heat treatment
control, Cr-Si particles of the sub-micron order are dispersion precipitated, thus improving stamping formability.
Figure 3 shows the leadframe surface after stamping. As
can be seen, EFTEC-64T-C gives smaller burrs at the cut
section, demonstrating improved stamping property.

45000
40000
35000

Others
Asia
China
Japan
EuropeNorth
America

30000
25000
20000
15000
10000
5000
0

2002

2003

2004

2005

2006 20072008

prediction prediction

Year

Figure 3

Status of burrs after stamping for EFTEC-64T and
EFTEC-64T-C.

Figure 4

Trends in the world’s sales of connectors (Bishop
Report 2006).

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Electronics-Related Metal Products of Furukawa Electric Group

1) EFTEC-97 and EFTEC-98S
EFTEC-97 and EFTEC-98S are based on the Cu-Ni-Si
system that is characterized by balanced property
between strength and electrical conductivity, thus realizing high strength, medium electrical conductivity characteristics (see Figure 6). And since a small amount of elements are added, they have made improvements in thebending and stress relaxation properties.
EFTEC-97 is mainly targeted at the low-concentration

Connector pitch (mm)

1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1980

1985

1990

1995

2000

2005

2010

beryllium copper market, and is expanding its applications centering on CPU sockets and FPC connectors. On
the other hand, EFTEC-98S has achieved improving thestrength of EFTEC-97 by increasing the amounts of Ni
and Si additions, so that the alloy is suitable for replacing
not only low-concentration beryllium copper, but also
high-concentration beryllium copper. Since these alloys
are provided with an outstanding modulus of elasticity ofas high as approximately 130 GPa, they allow for obtaining a high contact pressure with a small displacement,
achieving high reliability of contact even when used indownsized, small-height connectors. Figure 7 shows therelationship between material strength (yield strength)
and minimum bending radius (R/t) of selected copper
alloys, in which the bending workability of EFTEC-98S isseen to be equivalent to that of low-concentration beryllium copper.
2) F5218 and F5248
F5218 and F5248 have modified 8 % phosphor bronze forsprings and 10 % phosphor bronze for springs, respectively, by adding a small amount of Fe and Ni, thereby
improving the strength and bending workability while preserving the elastic spring performance of the conventional

Minimum bending radius (R/t, badway)electronic equipment is also expanding rapidly (seeFigure 4).
Electronic connectors are becoming significantly smaller in size, lower in height and narrower in pitch. As shownin Figure 5 which plots the trend in connector pitch, connectors having a pitch narrower than 0.3 mm are brought
into the market in these days, leading to the demand for amaterial that has higher strength and better workability.
Moreover, in recent years, there is a growing momentum to avoid beryllium in consideration of the environment, resulting in a requirement for developing a substitute copper alloy. Figure 6 shows the relationship between
tensile strength and electrical conductivity of various copper alloys for connectors. In the figure the alloys in red
are Furukawa Electric’s developments.

6
5
4
3

EFTEC-97
EFTEC-98S

2

Low-concentration
beryllium copper

1
0
500

600

Year

Electrical conductivity (%IACS)

100

Figure 7

Trends in connector pitch.

TPC

90
80
70
MSP-1

60

C17510（Cu-Be）

50
40

NB109

30

C7025
EFTEC-97
MAX251C C17530(Cu-Be)

EFTEC-98S

C17200（Cu-Be）

20

F5218 C19900（Cu-Be）

C5210

10
0
200

CAC60
KLF-5

F5248

300

400

500

600

700

800

900 1000 1100 1200

Minimum bending radius (R/t, badway)

Figure 5

Relationship between tensile strength and electricalconductivity of various copper alloys for connectors.

800

900

Relationship between yield strength and minimum
bending radius of selected copper alloys (I).

6
5

F5218
F5248
C5210
C5240

4
3

Low-concentration
beryllium copper

2
1
0
500

Tensile strength (MPa)Figure 6

700

Yield strength (MPa)

600

700

800

900

Yield strength (MPa)Figure 8

Relationship between yield strength and minimum
bending radius of selected copper alloys (II).

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Electronics-Related Metal Products of Furukawa Electric Group

3.1 Plated Strip Products
Most of the copper and copper alloy strips for electronicand electric equipment are used as plated, and they may
be categorized into “pre-plating” stocks where strips areplated before being press worked into parts, and “postplating” stocks where strips are plated after press working. For example, connector stocks for wire harness
mainly for in-vehicle use are largely pre-plated with Sn,
while those for electronic components are mainly postplated with precious metals. In these days, as the domestic automobile manufactures and automotive parts manufacturers make great strides worldwide, the demand forthese plated products is rapidly expanding. Accordingly,
Furukawa Electric is not the last to making and implementing plans to increase the production of these plated
products.
Figure 9 shows the trends in the worldwide sales ofautomobiles. Whereas the number of sales in Japan goessideways, that in the developing countries is still growing
headed by China. On the other hand, in the electronics
market both connectors and semiconductor devices are
growing.
1) Ag-Plated Stainless Steel Strip
As mobile phones become sophisticated in functions andthe strokes on the tact switches increase in number, there
arises a requirement for improved reliability of contacts.
This is particularly true for domestic mobile phones where

2) Partially Precious Metal-Plated Strip
Partially precious metal-plated strips, in particular those

8000
7000

OthersMiddleEast
Central andSouth America
Asia andPaciﬁcWest
EuropeNorth
America
Japan

6000
5000
4000
3000
2000
1000
0

Year

Figure 9

Trends in the worldwide sales of automobiles.

12
10
7.9

8
6

8.5

9.1

9.8

10.4

30
25

6.7

20

5.2

15

4

10

2
0

35

5
2003

2004

2005

2006

2007

2008

Rate of increase (%/year)

Our representative functional surface products include
plated alloy strip products having plated surface layers,
and resin coated metal strips “Furukawa F-Coat” products having electric insulating and heat-resistant resin
coatings. The strong point of Furukawa Electric is that we
can manufacture these functional surface products in an
integrated manner from the raw materials such as copperand copper alloy strips to the final products. This makes it
possible for us to offer very quickly a variety of cost-efficient high-quality products that meet the customers’
needs.
These products are targeted at two major markets: theIT and electronics market and the automotive market.
Below will be presented our functional surface products
targeted at these markets that are expected to expand
significantly in the future.

19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09

FUNCTIONAL SURFACE PRODUCTS

Number of sales (million/year)

3.

electronic mails and games have rapidly proliferated.
Conventionally for their contacts, stainless steel strips
with or without Ni plating were broadly used. But, Ag-plated stainless steel strip came gradually into use to improvethe contact reliability. Whereas the use was at first adopted only by domestic manufacturers which intended to
rapidly advance in sophistication of mobile phones, it isrecently gaining momentum among mobile phone manufacturers overseas, resulting in a rapid growth of demandfor Ag-plated stainless steel strip. Furukawa Electricaccordingly has been actively investing in plant andequipment aimed at expanding its production capacity.
Figure 10 shows the sales amount and rate of increaseof mobile phones in the world.
It has been reported that stainless steel has very poor
plating properties, so that it is allegedly difficult to form aplated coating of excellent adhesion. We have developed
an Ag-plated stainless steel strip provided with superior
adhesion, taking advantage of our proprietary technology
based on the long-accumulated plating technology.
Thanks to its high reliability, our products enjoy a domestic market share of more than 80 % accounting for aworldwide market share of more than 50 %.

Number of sales (hundred million/year)

phosphor bronze for springs (i.e., modulus of elasticity isapproximately 110 GPa).
Figure 8 shows the relationship between material
strength (yield strength) and minimum bending radius (R/t) of selected copper alloys including F5218 and F5248. It
can be seen that, compared with the conventional 8 %phosphor bronze for springs, and assuming the samelevel of minimum bending radius, F5218 allows for using
a material that is higher in yield strength by approximately
100 MPa, and as for F5248 by approximately 150 MPa,
thereby significantly upgrading the design flexibility.

2009

Year

Figure 10 Sales amount and rate of increase of mobile phones
in the world.

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Electronics-Related Metal Products of Furukawa Electric Group

using Au, have been heavily used in heavy-duty electronic connectors for their high reliability. Recently, connectors based on Au plating are gradually being applied, due
to their stabilized connection characteristics, to automotive safety systems such as ABS and air-bag equipment
where Sn plating still constitutes the mainstream. Thus
the use of Au-plated parts and connectors is rapidly
growing because of the accelerated computerization of
automotive equipment as well as of the worldwide business expansion of domestic automobile manufacturers.
Since precious metal plating is expensive, most of the
products employ partial plating instead of whole plating,and in addition, since the price of precious metals is soaring in recent year, the shift from the stripe plating wheremetals are plated in stripes to the spot plating where plating
is applied on contact points is being accelerated in order tosave precious metals by minimizing the amount of use.
Furukawa Electric begins considering an increased production system for precious metal plating to cope withsuch an accelerated market growth. Furukawa’s strong
point is its consistent production system involving the raw
materials and plating, which has resulted in the excellent

Before plating

After bending the plated stock

Furukawa s C2680R

Furukawa s C2680R
High reliability ispreserved evenafter bending,resulting in good
corrosion resistance

10Mm

Conventional C2680R

10Mm

Conventional C2680R

Direction of observation

W-bend (0.4R)

10Mm

10Mm

Figure 11 Improvement in the minimum bending radius of
C2680R.

12

bending workability of our products as shown in Figure 11.
3) Sn-Plated Strip
Nearly all Sn-plated strips are currently used as a material
for automotive terminals. The demand for this automotive
terminal stock is expected to grow in future as the production of automobiles expands, while the need is anticipated to diversify as the computerization of automobiles
proceeds along with the power hybridization.
Pb-free plating and reduction of insertion force are two
major technological trends in Sn-plated strips. As for Pbfree plating, the shift from conventional solder plating to
reflow Sn plating is being accelerated. With regard toinsertion force reduction, there is an increasing requirement for reducing the surface friction coefficient as theterminals become downsized and multi-poled.
In anticipation of demand increase in the future,
Furukawa Electric is planning to expand the production
facilities for reflow Sn plating. As for the low-insertion force
material, we have developed heat-resistant low-insertion
force Sn plating, in which the insertion force is reduced
and yet heat resistance is improved. Figure 12 shows the
low-insertion force characteristics of typical materials.
3.2 Resin Coated Alloy Strip “Furukawa F-Coat”
As mentioned earlier, mobile phones are increasing in
production volume worldwide. Domestically, despite thefact that they show a rather slow increase in number, they
are improving in terms of functions and reduction in sizeand height. As a result, there is an urgent requirement for
reducing the height of electronic parts in mobile phones.
A modular metal casing is used in every mobile phone
to shield the noise generated by the electronic components used in phones. Conventionally, a sufficient clearance was provided between the casing and the components, posing no particular problems of insulation.
Recently, however, the clearance became narrower, making it difficult to ensure ample electric insulation.
Accordingly, a solution was proposed to coat a strip stockwith resin, which was subsequently press-formed into a

0.7
090 terminal
040 terminal

0.6

Friction coeﬃcient

8

0.5

6

0.4

4

0.3

2

0.2

0

Conventionalreﬂow Sn plating

Friction coeﬃcient

Insertion force (N/pin)

10

Metal substrate(copper alloy, stainless steel, etc.)

Heat-resistant electric
insulation resin (PAI)

Plating for mounting
Heat-resistant(Sn, etc.)
under-plating (Ni, etc.)

0.1

Heat-resistant
low-insertion force Sn plating

Surface端子
observation
挿入後
after
terminal
insertion
表面
Shield casing

Figure 12 Low-insertion force characteristics of typical materials.

Shield casing
for mobile phone

Casing for handy camera

Figure 13 Structure and typical applications of F-COAT.

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Electronics-Related Metal Products of Furukawa Electric Group

4.

WIRE AND BAR PRODUCTS

Main products of wire and bar are experiencing somechanges. For example, the copper-plated steel wire forlead wire use with a product name “EF wire” and the electrode wire for electric discharge machines with a productname “FULLACE” have decreased in the market pricedue to the inflow of low-priced products from overseas
and the domestic overproduction. We have withdrawn
from the domestic production of EF wire in 2001 on theoccasion of a business merger with our affiliated company. As for FULLACE, we have introduced surface washingfacilities for removing adhesive particles, in an effort to differentiate our products by reducing shutdown troubles ofelectric discharge machines.
We are strengthening our efforts to enter into the electronics fields for our wire products, by improving material
properties and upgrading functions such as plating. With
regard to property improvement, we are developing various precipitation-type alloys utilizing our alloy design
technology that we have accumulated in the developmentof strip products. For example, EFTEC-194 W to be mentioned later has been adopted in a CPU of personal computers, making itself one of the main products of wire. In
addition, whereas conventionally the wire for connector
pins were used as solder-plated, we are specializing in
tin-plated products in line with the Pb-free trend, and the
products have been adopted as a pin stock for multi-pin
connectors in various electric and electronic equipment.
As the electric and electronic equipment develop in performance decreasing in size and weight in the future, thematerials used will advance toward smaller diameter andreduced thickness, raising requirements for materials ofhigh strength and high electrical conductivity. We plan todevelop materials that meet the market needs, thereby
strengthening our business development into electronicsrelated fields. In terms of the cross-section shape of wires
also, we plan to manufacture rectangular and speciallyshaped wires as well as conventional round and squarewires in order to cover wide ranges of applications.
Our main products of bar include rectangular bars of
tough pitch copper, oxygen-free copper and copper-sil-ver alloy, together with round bars of copper-chromium
alloy. Rectangular bars are used for bus bars, anodes formagnetron and rotor coils for motors. Copper-chromium
alloy is mainly used for electrodes of resistance welding
machines, and there is an emerging need for rectangularbars for rotor coil members of high-performance motors,
exploiting the high-strength and high-conductivity property of the alloy. We are now promoting entry into the newmarket by launching various precipitation-type alloys inthe same manner as for wire products.
We manufacture raw materials for both the wire and bar
products in-house through melting, billet casting and hot
processing. This makes our strong point because, while
control of alloy components and structures at these
upstream processes is essential for improving the properties of precipitation-type alloys, few manufacturers areable to implement these processes consistently.
Figure 14 shows the relationship between tensile
strength and electrical conductivity of alloys for wire andbar products. Our main products of today and their applications will be described below.
4.1 Wire Products1) EFTEC-194
EFTEC-194 W wire of our product 0.3 mm in diameterhas been adopted as lead pins for the PGA package thatis widely used in personal computer CPUs. This is a precipitation-type copper-iron alloy, where high bendability
and high electrical conductivity is obtained due to thefinely dispersed precipitates. Although Kovar (Fe-Ni-Co
alloy) was conventionally used in such an application, a
new material with higher electrical as well as thermal conductivity was needed as the operation speed of CPUs
increased, and, accordingly, CDA19400 alloy with anestablished track record as a leadframe strip came to be
used in this wire application. Since, in this application,
demanding requirements are imposed not only for

100
TPC（C1100W）

90

Electrical conductivity (%IACS)

casing. In this way, a resin coated metal casing can beobtained readily, resulting in eliminating the clearance
between the casing and the components, and hence realization of a low-profiled mobile phone.
Furukawa Electric has developed, using a proprietary
technology that the Company has cultivated for the adhesion between metal and resin, a composite strip stockthat offers sufficient resin adhesion against press forming.
Moreover, taking advantage of our strong point as a material manufacturer, we can consistently manufacture fromraw materials to final products, thereby making it possible
to offer various products that are excellent in terms of
quality, lead time and cost. The demand for the product is
expected to grow in the future.
Figure 13 shows the schematic structure and typicalapplications of this product.

CC

80

Developed alloy

70

EFTEC- 64

60

EFTEC- 1 9 450

EFTEC- 97

Conventional

40
30

Copper-beryllium
alloy (C1720)

Brass (C2700W)

20
Phosphor bronze(C5191W)

10
0

0

200

400

EFTEC- 98

600

800

1000

1200

1400 1600

Tensile strength (MPa)Figure 14 Relationship between tensile strength and electricalconductivity of the developed wire and bar.

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Electronics-Related Metal Products of Furukawa Electric Group

strength and electrical conductivity characteristics but
also for wire surface properties, we are developing manufacturing technologies such that the shape of the capstanin the drawing machine is designed in our proprietary way
so as to prevent possible generation of minute defects
during wire drawing.
2) EFTEC-98
Our EFTEC-98 BD wire 2~6 mm in diameter has been
adopted as pins in the SMA female coaxial connector thatis used in microwave communications. EFTEC-98 BD is
our original alloy with a small amount of additive elements
to the Corson alloy (i.e., a Cu-Ni-Si-based precipitationtype alloy with Ni-Si precipitates). Conventionally, freecutting copper-beryllium alloy (CDA17300 alloy based on
the Cu-Be-Pb system) and free-cutting phosphor bronze(JIS C5441 alloy based on the Cu-Pb-Sn-Zn-P system)
were widely used for their superior properties in springcharacteristics aging as well as in ease of fine cutting, but,
since they contain hazardous Pb or costly Be, thesealloys have been replace by EFTEC-98BD that is provided with the advantageous characteristics mentioned
above in addition to strength and electrical conductivity.
3) Reflow Sn-Plated Square Wire
Reflow Sn-plated square wire is used as a connector pin
stock. The base material is mainly brass or phosphor
bronze, and the cross section is square 0.3~1.0 mm on aside. Reflow is intended for suppressing generation of
whiskers specific to Sn plating, where the plating is melt
once and subsequently solidified. A uniform distributionof plating has been obtained thanks to our proprietaryreflow technology.
4.2 Bar Products
1) Copper-Chromium Alloy
Our rectangular bar of chromium-containing copper has
been adopted in the rotor coil of the motor for the N700
Shinkansen. Copper-tin alloy and copper-silver alloy conventionally used have been substituted by copper-chromium alloy with superior electrical conductivity andfatigue properties.
2) EFTEC-98
EFTEC-98 BD 13 mm in diameter has been adopted in
the bushing for the needle sliding shaft of an industrial
high-speed sewing machine. Conventionally, since thebushing is oil-free to keep the sewn clothes clean, copper-beryllium alloy (CDA17200 alloy based on the Cu-Be
system) has been used for its superior seize resistanceagainst steel shaft and wear resistance. EFTEC-98 BD issuperior to the CDA17200 alloy in terms of thermal conductivity and heat-dissipating property in addition to seize
resistance due to its dense metallographic structure, andit has been confirmed that the shaft and the bushing haveachieved a longer service life.

5.

ELECTRODEPOSITED COPPER FOIL
PRODUCTS

Copper foil is one of the major constituting materials forprinted circuit boards, and it comes in two types: electrodeposited type and rolled type.
Electrodeposited copper foil is manufactured in such a
way that a cylindrical titanium drum is used as the cathode, and its surface is copper plated during rotation, theresultant plated layer of copper is continuously peeled off
to be taken up in a roll. In contrast, rolled copper foil ismanufactured by repeatedly rolling a rectangular ingot ofcopper a number of times.
The electrodeposited copper foil is, due to such a difference in the manufacturing methods and in comparison
with the rolled copper foil, characterized by its ease of
manufacturing relatively thin foils and is manufacturable inlarge widths exceeding 1 meter, so that it is widely used in
the printed circuit boards in a variety of applications.
With its history of more than 30 years as an electrodeposited copper foil manufacturer, Furukawa Circuit Foil
Co., Ltd. is developing and releasing various new applications of copper foil targeted at flexible circuit boards,
build-up multilayer boards, semi-additive circuit boards
and circuit boards with embedded passive components,
as well as conventional rigid printed circuit boards.
Moreover, the company is expanding its sales targets at
different industries including not only printed circuitboards but also negative electrode copper foil for lithium
ion batteries and electromagnetic shielding copper foil for
PDPs.
Table 2 summarizes our main products of electrodeposited copper foils and their technological characteristics.

6.

Ni-Ti ALLOY

6.1 Ni-Ti Alloy Products
It is well known that Ni-Ti alloy has the shape memoryand super-elastic characteristics, so that a variety of
applications have been developed so far. On the other
hand, with its rather short history of around 40 years, it
may be called a very young alloy when compared to otherordinary alloys. Its transformation temperature can bearbitrarily changed between a range of 0~100°C by controlling the atomic composition of Ni-Ti around a point of
50:50. Products whose transformation temperature is
below room temperature and which are used at room
temperature are super-elasticity products, while those
whose transformation temperature is above room temperature and which take advantage of the shape recovery
effect when heat is applied are shape memory products.
The Ni-Ti alloy is superior to other shape memory alloys
in terms of shape memory properties, workability and corrosion resistance, so that it dominates in practical applications.
It may be said that Ni-Ti alloy products belong to aclass of typical development-oriented products, where itis essential how to make its new functions develop into
new applications. This presents a challenging problem for

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Electronics-Related Metal Products of Furukawa Electric Group

Table 2Category

Types and characteristics of electrodeposited copper foils.

Main uses

Two-layered flexible circuit board
Package circuit board

LCD polymer circuit board
High-frequency circuit board

Printed circuitboard copper foil

Copper foil forbuild-up multilayer circuit board
for mobile phones

Chip on film (COF)
High-frequency circuit board

Foil type

Thickness（µm）

Features and advantages

WS

9
12
18

・Low surface roughness resulting in ease of finepattern forming・High adhesion with resin
・Superior bending resistance

WS

9
12
18

・Low surface roughness resulting in ease of finepattern forming・High adhesion with resin
・Superior radio frequency characteristics

U

WZ

9
12
18

・Lower surface roughness than F-WS foil resulting in ease of fine pattern forming and superior
high-frequency characteristics
・High adhesion
・Superior bending resistance

9
12
18
35
70

・High adhesion with resin
・Superior heat resistance

Surface treatment

One side

One side

One side

F0
F1
F2
F3

FWL

Multilayer circuit board
High-density multilayer circuit board
Build-up circuit board
Tree-layer flexible circuit board

One side

GTS

STD
MP

Large current circuit board
Heat-dissipative package circuit board
Automotive circuit board

One side

GTS

STD

105
140
175
210

・High adhesion with resin
・Superior heat resistance

Any Layer Interstitial Via Hole
(ALIVH †) substrate

Both sides

GLD

STD

9
12
18

・Both sides roughening treated achieving highreliability bonding・Both sides roughening treated suppressing
copper powder dropping

F

DP

U

HP

FWL

HP

1
3
5
9

・Ultra-thin peelable layer 1~9 μm in thickness isformed on carrier copper foil・Ultra-fine pattern can be formed
・Stabilized carrier peel strength・HP type is peelable even after hot processes of
300°C

FR

WS

12
18

・Copper foil with electrical resistance layer on the surface
・Used in circuit boards with embedded passive
components eliminating conventional external
resistors
・Smooth surface for both sides
・Large elongation
・Superior bending resistance・Black surface treatment for luxury goods
・Low surface roughness resulting in ease of grid
pattern forming

Ultra-thin peelable copper foilwith copper
carrier

Package circuit board
Fine pattern circuit board

Copper foil withresistance layer

Mobile electronic equipment circuit board for mobile phones,
etc.

Negative electrode copper
foil for lithium
ion batteries

Negative electrode for lithium ion
batteries

Electromagnetic
shielding copper
foil for PDPs

Electromagnetic shielding for
PDPs

With carrier

One side

-

NC

WS

6
8
10
15
20

One side

B

WS

10

† ALIVH is a registered trade mark of Matsushita Electric Industrial Co., Ltd.

manufacturers, which is a source of concern, i.e., theshort life cycle of products. Thus, our main products inthe past 20 years went through changes from core wire
for women’s brassiere to whip antenna for mobile phones.
Currently, we are promoting product development specifically targeted at our new entry area of medial applications
while pushing forward the sales of spring stocks and eyeglass frame stocks.

6.2 Problems at Manufacturing Processes
1) Property Control
The composition of Ni-Ti alloy exerts a strong influenceon the transformation temperature, such that a variationof 0.1 at % in alloy composition results in a transformation
temperature difference of about 10°C. Since the causative
factors include fluctuation in composition ratio and impurity levels such as carbon and oxygen, it is essential tocontrol the casting conditions including degree of vacu-

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2007

41

Electronics-Related Metal Products of Furukawa Electric Group

6.3

New Applications of Super-Elasticity in the
Medical Treatment Area
It can be said that the applications of Ni-Ti alloy in the
medical treatment area are the best suited ones, since theapplications utilize the body temperature within thehuman body, being simultaneously helped by the superior biocompatibility and corrosion resistance of Ni-Ti alloy.
Recent years have seen various application developmentsof this superior super-elasticity in the medical treatmentarea centering on Europe and the United States. Theirsocial background comprises hardened arteries causedby high-calorie meals and piled-up stress from the modern society, in addition to the medical treatment developments for vascular diseases represented by brain infarction. Recently, the medical treatment has made a remarkable progress making a shift from the abdominal operation-based techniques conventionally used to the modern
interventional techniques with improvements in healthimpact and biomedical impact, which include guide wire,catheter, stent, etc. Biomedical treatment devices using
the super-elastic effect of Ni-Ti alloy are under development also outside of vascular diseases, so that it isexpected that the technology develops further.
On the other hand, there have been concerns about thebiomedical safety of Ni-Ti alloy such as nickel allergy andthe fact that nickel is a target substance of environmental
regulations. However, with its low solubility comparable tothat of stainless steel, the biomedical safety of Ni-Ti alloy
is known to be sufficiently high. In Europe and the UnitedStates, in case of medical applications, compliance validation to the new standard ASTM-F2063 is oftentimes
required. Thus, study on the biomedical safety of Ni-Ti
alloy is advancing.

2) Ni-Ti Alloy Tube
Although Ni-Ti alloy is generally described as less workable, tubesφ10~φ0.3 in diameter have come to be manufacturable in recent years (see Figure 16). And, using
Ni-Ti alloy tubes, various medical treatment devices have

1600

1600

1400

1400

1200

1200

Stress（MPa）

2) Workability
Since Ni-Ti alloy is an intermetallic compound, its workability is very low thus presenting many manufacturing
problems. During cold working, the reduction ratio
between annealing has to be held at approximately 40 %since the workability is deteriorated due to work hardening. A 12-stand hot rolling machine based on three-rollmill that was introduced in 1997 helped us a great deal to
improve the productivity, significantly contributing to thesales promotion of the mobile phone antennas mentioned
before.
In addition to this low workability, the shape memoryand super-elastic properties also cause manufacturing
problems, whereby the materials once processed try torecover their original configurations. This causes many
problems such as difficult drawn wire size control, poor
machinability and configuration changes during annealing. For these reasons, dedicated facilities are used in the
production line, excluding general Ni products.

1) Guide-Wire for Medical Treatment
Guide-wires for medical treatment utilizing super-elasticity are required to provide stiffness, straightness andtorque transmitting abilities in order to smoothly passthrough the complicated vascular system of the humanbody. Ni-Ti alloy wires have heretofore been employedsince they outperform stainless steel wires in theserespects. A new product called FHP-NT (see Figure 15-1)
that does not show stress plateau has been developed toachieve higher pushability and superior torque transmitting abilities.
We have developed in-house the manufacturing equipment for FHP-NT, and this has led to acquiring new customers. Moreover, we have additionally installed the same
type of equipment, thereby successfully increasing the
product variations in size and strengthening the production capacity. With regard to the guide-wire of conventional super-elasticity type (see Figure 15-2), we arestrengthening our unique technologies since we are having more advanced product requirements as the medical
treatment technology advances in recent years.

Stress（MPa）

um. We use a vacuum induction furnace melting (VIM)
furnace in the melting and casting process for Ni-Ti alloy,
thereby managing the alloy compositions depending on
application.

1000
800
600

1000
800
600

400

400

200

200

0

0

2

4

6

8

0

0

2

4

6

8

Strain（%）

Strain（%）（1）FHP-type（2）Super-elasticity typeFigure 15 Property of guide-wires.

Figure 16 Ni-Ti tubes.

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2007

42

Electronics-Related Metal Products of Furukawa Electric Groupbeen developed and released including catheter, stent(see Figure 17), reamer, etc. In order to meet the stringent
requirements for Ni-Ti tubes with respect to the wall thickness uniformity and the outer- and inner-diameter tolerances, process management that is more complicatedthan that for wires is needed, and this leads to overcoming the manufacturing difficulties due to super-elasticity
property. To cope with such problems mentioned above,it is indispensable to introduce new facilities and to develop new technologies. We are also proactively introducing
the improvement promotion activities, which contributes agreat deal to productivity improvement.
Figure 17 Appearance of stent made of Ni-Ti tubing. (By courtesy of Biotronik GmbH&Co)

3) Cored Wire
When a doctor performs an external operation using an
X-ray display as is the case with catheter operation, thetransmissivity of the guide-wire has to be high as muchas possible. For this purpose, an alloy wire containing
additive elements for transmissivity improvement has
been developed together with the cored wire having acore of platinum or gold, an application of tubing technology, as shown in Figure 18.

7.

CONCLUSION

We have presented here electronics-related metal products of Furukawa Electric Group.
Figure 18 Cored wire.

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