U.S. patent application number 12/886268 was filed with the patent office on 2011-01-13 for copper alloy material for electric/electronic parts.
Invention is credited to Tatsuhiko EGUCHI, Ryosuke MATSUO, Kuniteru MIHARA.
Application Number | 20110005644 12/886268 |
Document ID | / |
Family ID | 41091047 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110005644 |
Kind Code |
A1 |
MATSUO; Ryosuke ; et
al. |
January 13, 2011 |
COPPER ALLOY MATERIAL FOR ELECTRIC/ELECTRONIC PARTS
Abstract
A copper alloy material for an electric/electronic part,
containing Co 0.5 to 2.5 mass % and Si 0.1 to 1.0 mass %, at a
ratio of Co/Si of 3 to 5 in terms of mass ratio, with the balance
of Cu and inevitable impurities, which is obtained by subjecting to
a solution treatment at a temperature (.degree. C.) from
800.degree. C. to 960.degree. C. and lower than
-122.77X.sup.2+409.99X+615.74, in which X represents the Co content
in mass %.
Inventors: |
MATSUO; Ryosuke; (Tokyo,
JP) ; EGUCHI; Tatsuhiko; (Tokyo, JP) ; MIHARA;
Kuniteru; (Tokyo, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
41091047 |
Appl. No.: |
12/886268 |
Filed: |
September 20, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2009/055531 |
Mar 19, 2009 |
|
|
|
12886268 |
|
|
|
|
Current U.S.
Class: |
148/435 ;
148/432; 148/436 |
Current CPC
Class: |
C22F 1/08 20130101; C22C
9/06 20130101; H01B 1/026 20130101 |
Class at
Publication: |
148/435 ;
148/432; 148/436 |
International
Class: |
C22C 9/06 20060101
C22C009/06; C22C 9/00 20060101 C22C009/00; C22C 9/01 20060101
C22C009/01; C22C 9/10 20060101 C22C009/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2008 |
JP |
2008-074650 |
Claims
1. A copper alloy material for an electric/electronic part,
comprising Co 0.5 to 2.5 mass % and Si 0.1 to 1.0 mass %, at a
ratio of Co/Si of 3 to 5 in terms of mass ratio, with the balance
of Cu and inevitable impurities, which is obtained by subjecting to
a solution treatment at a temperature Ts .degree. C. from
800.degree. C. to 960.degree. C. and lower than
-122.77X.sup.2+409.99X+615.74, in which X represents the Co content
in mass %.
2. The copper alloy material for an electric/electronic part
according to claim 1, which has a yield stress of not less than 500
MPa but less than 650 MPa, an electrical conductivity of 60% IACS
or more, and a value R/t representing a bending property of less
than 0.5.
3. The copper alloy material for an electric/electronic part
according to claim 1, which has a yield stress of 650 MPa or more,
an electrical conductivity of 50% IACS or more, and a value R/t
representing a bending property of less than 1.5.
4. The copper alloy material for an electric/electronic part
according to claim 1, which has a yield stress of not less than 500
MPa but less than 650 MPa, an electrical conductivity of 60% IACS
or more, and a value R/t representing a bending property of 1.2 or
less, with respect to each of a sample parallel to a rolling
direction and a sample perpendicular to the rolling direction.
5. The copper alloy material for an electric/electronic part
according to claim 1, which has a yield stress of 650 MPa or more,
an electrical conductivity of 50% IACS or more, and a value R/t
representing a bending property of 1.5 or less, with respect to
each of a sample parallel to a rolling direction, and a sample
perpendicular to the rolling direction.
6. A copper alloy material for an electric/electronic part,
comprising Co 0.5 to 2.5 mass % and Si 0.1 to 1.0 mass %, at a
ratio of Co/Si of 3 to 5 in terms of mass ratio, and comprising
0.01 to 1.0 mass % of one or two or more selected from the group
consisting of Cr, Mg, Mn, Sn, V, Al, Fe, Ni, Ti and Zr, with the
balance of Cu and inevitable impurities, which is obtained by
subjecting to a solution treatment at a temperature Ts .degree. C.
from 800.degree. C. to 960.degree. C. and lower than
-94.643X.sup.2+329.99X+677.09, in which X represents the Co content
in mass %.
7. The copper alloy material for an electric/electronic part
according to claim 6, which has a yield stress of not less than 500
MPa but less than 650 MPa, an electrical conductivity of 60% IACS
or more, and a value R/t representing a bending property of less
than 0.5.
8. The copper alloy material for an electric/electronic part
according to claim 6, which has a yield stress of 650 MPa or more,
an electrical conductivity of 50% IACS or more, and a value R/t
representing a bending property of less than 1.5.
9. The copper alloy material for an electric/electronic part
according to claim 6, which has a yield stress of not less than 500
MPa but less than 650 MPa, an electrical conductivity of 60% IACS
or more, and a value R/t representing a bending property of 1.2 or
less, with respect to each of a sample parallel to a rolling
direction and a sample perpendicular to the rolling direction.
10. The copper alloy material for an electric/electronic part
according to claim 6, which has a yield stress of 650 MPa or more,
an electrical conductivity of 50% IACS or more, and a value R/t
representing a bending property of 1.5 or less, with respect to
each of a sample parallel to a rolling direction, and a sample
perpendicular to the rolling direction.
Description
TECHNICAL FIELD
[0001] The present invention relates to a copper alloy material
applied to electric/electronic parts.
BACKGROUND ART
[0002] Hitherto, brass (C2600) and phosphor bronze (C5191, C5212,
C5210), as well as beryllium copper (C17200, C17530) and Corson
alloy (C7025), and the like, have been used for connectors,
terminals, relays, switches, and the like, for electronic/electric
equipments.
[0003] In recent years, since a frequency of electric current
applied to the electronic/electric equipments using those alloys
becomes high, and a substantial electrical conductivity is lowered
due to a skin effect, materials for the parts have been required to
have a high electrical conductivity. Although brass and phosphor
bronze each originally have a low electrical conductivity and the
Corson copper alloy shows a medium electrical conductivity (EC
nearly equals to 40 to 50% IACS) as a connector material, a higher
electrical conductivity has been required. Further, beryllium
copper has the medium electrical conductivity, but it is expensive.
Still further, it is well known that since beryllium is an
environment load substance, beryllium copper has been studied to be
replaced with another copper alloy, and the like. On the other
hand, pure copper (C1100), tin bearing copper (C14410), and the
like, which have a high electrical conductivity, have a drawback
that their mechanical strength is low. Thus, a copper alloy has
been desired which has an electrical conductivity higher than that
of a conventional Corson copper, and a tensile strength and a
bending property at the same level of those of the conventional
Corson copper.
[0004] The CXXXXX denotes types of copper alloys specified in JIS,
and "% IACS" is an abbreviation of "International Annealed Copper
Standard" and is a unit which indicates an electrical conductivity
of a material.
[0005] In general, electrical conductivity and mechanical strength
are incompatible properties. Examples of a method for enhancing the
strength, include solid-solution strengthening, working
strengthening, precipitation strengthening, and the like. Among
them, it is known that the precipitation strengthening is a promise
as a method for enhancing the strength of the copper alloy without
deteriorating the electrical conductivity. In this precipitation
strengthening, an alloy, to which an element(s) which precipitates
is added, is heat-treated at a high temperature, so as to cause
solid solution of the element(s) in a copper matrix, and then, the
resultant alloy is heat-treated at a temperature lower than said
high temperature, thereby to precipitate the element(s) of the
solid solution. For example, this strengthening method is adopted
for beryllium copper, the Corson alloy, and the like.
[0006] Meanwhile, there are known alloys containing an
intermetallic compound of cobalt (Co) and silicon (Si) in copper,
besides the beryllium copper, the Corson alloy, and the like.
Further, there is a copper alloy containing Co and Si, and Mg, Sn
and Zn, from which a material having a high strength and a high
electrical conductivity can be produced at a low cost. The copper
alloy contains Co and Si each at a lower concentration than that of
a conventional copper alloy containing Co and Si each at a high
concentration (Co content: 2 to 4 mass %, the amount ratio of
Si/Co: 1/4) (see, for example, Patent Literature 1).
[0007] In the production of this copper alloy described in Patent
Literature 1, a method is adopted, in which a solution treatment
temperature is set high (for example, 950.degree. C. in the example
of Patent Literature 1), the elements are sufficiently made into a
solid solution in copper, and then a precipitation-hardening is
conducted by a heat treatment.
[0008] However, this method causes the coarsening of grains. It is
known that, in an alloy structure, if a grain size is coarsened, a
bending property is poor. With conventional copper alloys obtained
through solution treatment, it is impossible to attain a favorable
bending property.
{Patent Literature 1} JP-A-63-307232 ("JP-A" means unexamined
published Japanese patent application)
DISCLOSURE OF INVENTION
Technical Problem
[0009] The present invention is contemplated for providing a copper
alloy material for electric/electronic parts, which can be
favorably used in products subjected to severe bending, such as
connectors or the like, and which is excellent in mechanical
strength, electrical conductivity, and bending property.
Solution to Problem
[0010] According to the present invention, there is provided the
following means:
[0011] (1) A copper alloy material for an electric/electronic part,
comprising Co 0.5 to 2.5 mass % and Si 0.1 to 1.0 mass %, at a
ratio of Co/Si of 3 to 5 (mass ratio), with the balance of Cu and
inevitable impurities, which is obtained by subjecting to a
solution treatment at a temperature Ts (.degree. C.) from
800.degree. C. to 960.degree. C. and lower than
-122.77X.sup.2+409.99X+615.74, in which X represents the content
(mass %) of Co;
[0012] (2) A copper alloy material for an electric/electronic part,
comprising Co 0.5 to 2.5 mass % and Si 0.1 to 1.0 mass %, at a
ratio of Co/Si of 3 to 5 (mass ratio), and comprising 0.01 to 1.0
mass % of one or two or more selected from the group consisting of
Cr, Mg, Mn, Sn, V, Al, Fe, Ni, Ti and Zr, with the balance of Cu
and inevitable impurities, which is obtained by subjecting to a
solution treatment at a temperature Ts (.degree. C.) from
800.degree. C. to 960.degree. C. and lower than
-94.643X.sup.2+329.99X+677.09, in which X represents the content
(mass %) of Co;
[0013] (3) The copper alloy material for an electric/electronic
part as described in the item (1) or (2), which has a yield stress
of not less than 500 MPa but less than 650 MPa, an electrical
conductivity of 60% IACS or more, and a value (R/t) representing a
bending property of less than 0.5;
[0014] (4) The copper alloy material for an electric/electronic
part as described in the item (1) or (2), which has a yield stress
of 650 MPa or more, an electrical conductivity of 50% IACS or more,
and a value (R/t) representing a bending property of less than
1.5;
[0015] (5) The copper alloy material for an electric/electronic
part as described in the item (1) or (2), which has a yield stress
of not less than 500 MPa but less than 650 MPa, an electrical
conductivity of 60% IACS or more, and a value (R/t) representing a
bending property of 1.2 or less, with respect to each of a sample
parallel to a rolling direction and a sample perpendicular to the
rolling direction; and
[0016] (6) The copper alloy material for an electric/electronic
part as described in the item (1) or (2), which has a yield stress
of 650 MPa or more, an electrical conductivity of 50% IACS or more,
and a value (R/t) representing a bending property of 1.5 or less,
with respect to each of a sample parallel to a rolling direction,
and a sample perpendicular to the rolling direction.
[0017] Herein, the value (R/t) representing a bending property
means a value R/t obtained as follows: cutting out samples with a
respective sheet thickness and with a sheet width w of 10 (mm) from
a test specimen; rubbing lightly the surface of the sample with
metal polishing powders, to remove an oxide layer; subjecting the
resultant sample to W-bending, such that the inner angle of bending
would be 90.degree., with respect to two kinds of: [1] bending (GW)
of the sample parallel to the rolling direction, and [2] bending
(BW) of the sample perpendicular to the rolling direction; and
dividing the smallest bending radius R (mm) at which no
micro-cracks occur, by a sample's sheet thickness t (mm). In the
present invention, the bending property is evaluated with this
value R/t.
ADVANTAGEOUS EFFECTS OF INVENTION
[0018] The copper alloy material of the present invention for
electric/electronic parts is excellent in all of the mechanical
strength, the electrical conductivity, and the bending property.
The copper alloy material of the present invention for
electric/electronic parts can be favorably used even in the
products subjected to severe bending, such as connectors or the
like.
[0019] Other and further features and advantages of the invention
will appear more fully from the following description.
BEST MODE FOR CARRYING OUT THE INVENTION
[0020] With respect to an alloy composition of the copper alloy
material of the present invention, a preferable embodiment is
explained in detail below. The copper alloy material of the present
invention is a copper alloy material having a specific shape, such
as a sheet material, a strip material, a wire material, a rod
material, a foil, and the like, and the copper alloy material can
be used for any electric/electronic parts. The electric/electronic
parts are not specifically limited. The copper alloy material is
favorably used, for example, for connectors, terminal materials,
and the like; particularly, high-frequency relays and switches,
which are desired to be high in electrical conductivity, or
connectors, terminal materials, lead frames, and the like, which
are mounted in vehicles or the like.
[0021] In the copper alloy composition according to the present
invention, Co and Si are essential elements. Co and Si in the
copper alloy mainly form a precipitate of a Co.sub.2Si
intermetallic compound, thereby to enhance the strength and the
electrical conductivity.
[0022] The content of Co is 0.2 to 2.5 mass %, preferably 0.3 to
2.0 mass %, more preferably 0.5 to 1.6 mass %. The content of Si is
0.1 to 1.0 mass %, preferably 0.1 to 0.7 mass %, more preferably
0.1 to 0.5 mass %. The reason why their contents are specified is
explained as follows. As described above, these mainly form the
precipitate of the intermetallic compound of Co.sub.2Si, to
contribute to the precipitation strengthening. If the content of Co
is less than 0.5 mass %, the precipitation strengthening degree is
small, and if the content of Co is more than 2.5 mass %, the effect
due to Co is saturated. Further, from a stoichiometric proportion,
the optimum addition ratio of the compound is Co/Si nearly equals
to 4.2, and the addition amount of Si is determined to be in this
range. It is preferable to control the Co/Si to be within a range
of 3.0 to 5.0, more preferably within a range of 3.2 to 4.5, with
the above-mentioned value to be the central value. Hereinafter, Si
and Co may be referred to as "elements I to be added".
[0023] In the case of a copper alloy having the above-mentioned
composition, the temperature Ts (.degree. C.) for conducting the
solution treatment is from 800.degree. C. to 960.degree. C., and
lower than -122.77X.sup.2+409.99X+615.74 (.degree. C.), in which
the Co content (mass %) is represented by X.
[0024] To the copper alloy of the present invention, it is
preferable to add one or two or more kinds of any of Cr, Mg, Mn,
Sn, V, Al, Fe, Ni, Ti, and Zr, and the addition amount thereof is
0.01 to 1.0 mass %. Hereinafter, these Cr, Mg, Mn, Sn, V, Al, Fe,
Ni, Ti, and Zr may be referred to as "element(s) II to be
added".
[0025] When the addition amount of the element(s) II to be added is
less than 0.01 mass %, the effect due to the addition is small.
When the addition amount is more than 1.0 mass %, any of the
following occurs: <1> the electrical conductivity
conspicuously lowers, by the element(s) making a solid-solution,
such as Mg, Mn and Sn; <2> the strength lowers by a
precipitation other than the timing of an aging, or a solution
temperature raises due to a raise of a solid-solution temperature,
by the element(s) which accelerate(s) the precipitation, such as
Cr, V, Al, Fe, Ni, Ti, and Zr; and <3> a casting become
difficult to be conducted, due to a conspicuous oxidation, by Cr,
Mg, Al, Ti, and Zr.
[0026] Among these elements II to be added, Cr, Ni, and Fe have a
function of forming a Co-.chi.-Si compound (.chi.=Cr, Ni or Fe), to
enhance the strength, by being replaced with a part of Co in a main
precipitate phase.
[0027] Mg, Mn, and Sn have an action of making a solid solution in
the copper matrix, to strengthen the copper alloy. Mg and Mn also
exhibit an effect for improving a hot workability.
[0028] V, Al, Ni, Ti, and Zr have an action of forming a compound
together with Co and Si, to strengthen and suppress coarsening of
the grains.
[0029] A preferable method of producing the copper alloy material
according to the present invention includes the following steps.
That is, such steps are:
melt-casting.fwdarw.re-heat-treatment.fwdarw.hot
rolling.fwdarw.cold rolling.fwdarw.solution treatment.fwdarw.aging
heat-treatment.fwdarw.final cold-rolling.fwdarw.stress-relief
annealing. The order of the aging heat-treatment and the final
cold-rolling may be reversed. The stress-relief (low-temperature)
annealing to be finally conducted may be omitted.
[0030] In the present invention, the solution treatment before
subjecting to the final rolling is conducted at a temperature from
800.degree. C. to 960.degree. C.
[0031] Further, in the case where the copper alloy material does
not contain any of the elements II to be added, the solution
treatment temperature Ts (.degree. C.) is set to a temperature
(.degree. C.) lower than -122.77X.sup.2+409.99X+615.74, in which
the Co content (mass %) is represented by X.
[0032] On the other hand, in the case where the copper alloy
material contains the element(s) II to be added at the content
described above, the solution treatment temperature Ts (.degree.
C.) is set to a temperature (.degree. C.) lower than
-94.643X.sup.2+329.99X+677.09, in which the Co content (mass %) is
represented by X.
[0033] The heat treatment at this temperature determines the grain
size in the copper alloy material.
[0034] Further, in the present invention, it is preferable to
conduct a rapid cooling (quenching) at a cooling speed of
50.degree. C./sec or more, from this solution heat-treatment
temperature Ts. If the cooling speed in the quenching is too low,
the elements made to be a solid solution at the aforementioned high
temperature, may precipitate.
[0035] Particles (compounds), precipitated upon cooling at such a
too low cooling speed (for example, at a cooling speed lower than
50.degree. C./sec), are non-coherent precipitates that do not
contribute to the strength. Further, this non-coherent precipitate
may contribute as a nucleation site when a coherent precipitate is
formed in the subsequent aging heat-treatment step, and may
accelerate the precipitation of a part in which the coherent
precipitate formed, and resultantly may affect as negatively to the
properties.
[0036] Thus, the cooling speed is preferably 50.degree. C./sec or
more, more preferably 80.degree. C./sec or more, and even more
preferably 100.degree. C./sec or more. Unless the cooling speed is
not over a practical upper limit, it is preferably as fast as
possible.
[0037] This cooling speed means an average cooling speed from the
high temperature of the solution heat-treatment temperature to
300.degree. C. Since the structure is not varied largely at a
temperature less than 300.degree. C., it is enough to control
appropriately the cooling speed to this temperature.
[0038] In the present invention, in order to attain favorably the
properties of the copper alloy material having the aforementioned
composition, the solution treatment temperature is defined.
[0039] In the present invention, the grain size is preferably 20
.mu.m or less, and more preferably 10 .mu.m or less. The reason as
assumed is because, if the grain size is more than 20 .mu.m, due to
the coarse grain size, a grain boundary density is low and a
bending stress cannot be sufficiently absorbed, to deteriorate the
workability. The lower limit of the grain size is not particularly
limited, but is generally 3 .mu.m or more. The "grain size" means a
value measured according to JIS-H0501 (cutting method) described
below.
[0040] Herein, the "size of a precipitate" is an average size of
the precipitate, as determined by a method described below.
[0041] In one preferable embodiment of the copper alloy material of
the present invention for electric/electronic parts, the copper
alloy material has properties of: a yield stress of not less than
500 MPa but less than 650 MPa; an electrical conductivity of 60%
IACS or more; and a bending property (R/t) of less than 0.5.
Herein, the "bending property (R/t) of less than 0.5" means that,
at least, a R/t value, in the bending of the sample parallel to a
rolling direction, is less than 0.5; and it is preferably that R/t
values are less than 0.5, in both of the bending of the sample
parallel to the rolling direction and the bending of the sample
perpendicular to the rolling direction.
[0042] In another preferable embodiment of the copper alloy
material of the present invention for electric/electronic parts,
the copper alloy material has properties of: a yield stress of 650
MPa or more; an electrical conductivity of 50% IACS or more; and a
bending property (R/t) of less than 1.5. Herein, the "bending
property (R/t) of less than 1.5" means that, at least, a R/t value,
in the bending of the sample parallel to the rolling direction, is
less than 1.5; and it is preferably that R/t values are less than
1.5, in both of the bending of the sample parallel to the rolling
direction and the bending of the sample perpendicular to the
rolling direction.
[0043] In still another preferable embodiment of the copper alloy
material of the present invention for electric/electronic parts,
the copper alloy material has properties of: a yield stress of not
less than 500 MPa but less than 650 MPa; an electrical conductivity
of 60% IACS or more; and the value (R/t) representing the bending
property of 1.2 or less (more preferably 1.0 or less, and even more
preferably 0.6 or less), in both of the bending of the sample
parallel to the rolling direction and the bending of the sample
perpendicular to the rolling direction.
[0044] In further another preferable embodiment of the copper alloy
material of the present invention for electric/electronic parts,
the copper alloy material has properties of: a yield stress of 650
MPa or more; an electrical conductivity of 50% IACS or more; and
the value (R/t) representing the bending property of 1.5 or less
(more preferably 1.2 or less), in both of the bending of the sample
parallel to the rolling direction and the bending of the sample
perpendicular to the rolling direction.
[0045] As mentioned above, the copper alloy material of the present
invention high in the electrical conductivity and mechanical
strength, and excellent in the bending property, can be favorably
used in electric/electronic parts, such as connectors, subjected to
severe bending.
EXAMPLES
[0046] Hereinafter, the present invention is explained in more
detail based on the following examples, but the invention is not
intended to be limited to those.
Reference Example 1
[0047] Alloys (Nos. 1 to 9) composed of elements as shown in Table
1, with the balance of Cu and inevitable impurities, were melted
with a high-frequency melting furnace, followed by casting at a
cooling speed of 10 to 30.degree. C./sec, to obtain ingots with
length 180 mm, width 30 mm, and height 110 mm, respectively.
[0048] The thus-obtained ingots were maintained at 1,000.degree. C.
for 30 minutes, followed by working to thickness 12 mm by hot
rolling. After the hot rolling, the thus-hot-rolled alloys were
immediately quenched by water cooling, followed by face-milling to
thickness about 10 mm to remove an oxide layer on the surface of
the alloy, and then working by cold rolling. Then, for the purposes
of conducting solution-treatment and recrystallization, the
resultant alloys were heat-treated by maintaining at 950.degree. C.
for 30 seconds, followed immediately by quenching by water
cooling.
[0049] In the above, the temperature raising speed to reach the
highest temperature from the room temperature was within the range
of 10 to 50.degree. C./sec, and the cooling speed was within the
range of 30 to 200.degree. C./sec.
[0050] Thereafter, the surface oxide layer was removed, and the
alloys were subjected to cold rolling, according to necessity. This
cold-rolling also functioned to work hardening, and acceleration of
precipitation hardening in heat treatment of the subsequent
step.
[0051] Then, for the purpose of allowing aging precipitation, the
alloys were subjected to a heat treatment at 525.degree. C. for 120
minutes. In the above, the temperature raising speed to reach the
highest temperature from the room temperature was within the range
of 3 to 25.degree. C./min, and in the temperature lowering, the
cooling was conducted at a speed within the range of 1.degree.
C./min to 2.degree. C./min in the furnace, to 300.degree. C. which
was a temperature sufficiently lower than the temperature range
presumed to affect the precipitation.
[0052] After the aging heat treatment, the cold rolling was
conducted, so as to reduce 20% of the sheet thickness. For each
kind of the alloys, test materials were produced with sheet
thickness 0.10 mm, 0.15 mm, 0.20 mm, and 0.25 mm, respectively.
[0053] Then, the resultant materials were subjected to a heat
treatment at 350.degree. C. for 30 minutes. In the above, the
temperature raising speed to reach the highest temperature from the
room temperature was within the range of 3 to 25.degree. C./min,
and in the temperature lowering, the cooling was conducted at a
speed within the range of 1.degree. C./min to 2.degree. C./min in
the furnace, to 300.degree. C. which was a temperature sufficiently
lower than the temperature range presumed to affect the
precipitation.
[0054] Among the thus-produced alloy materials of Alloy Nos. 1 to
8, with respect to the respective alloy material with sheet
thickness 0.20 mm, a yield stress (YS), a tensile strength (TS),
and an electrical conductivity (EC) were measured by the methods
described below. The results are shown in Table 3. With respect to
the alloy material of Alloy No. 9, it was difficult to conduct the
hot rolling due to excessive precipitation and crystallization, and
no final product was produced, thus no measurements below were
conducted.
[0055] Methods of measuring the yield stress and the tensile
strength: each two test pieces that were cut out from the direction
parallel to the rolling direction according to JIS Z2201-5 were
measured according to JIS Z2241; and the average value (MPa)
thereof was calculated.
[0056] The yield stress was measured according to an offset method.
That is, a proof stress, in the case where a permanent elongation
was 0.2%, was calculated by using an expression:
.sigma..sub.0.2=F.sub.0.2/A.sub.0. In the expression, .sigma.
represents a proof stress (N/mm.sup.2) calculated by the offset
method; and F represents a force, which was determined, by
obtaining a relationship curve diagram between a force and a ratio
of elongation using an elongation meter, drawing a line parallel to
the straight line part of the early stage of the test, from the
point on the axis of elongation corresponding to the predetermined
permanent elongation (.epsilon. %), and determining the force shown
at the point at which the parallel line intersects the curve
diagram.
[0057] Method of measuring the electrical conductivity: the
electrical conductivity (% IACS) was calculated, by measuring a
specific resistance of the material through a four terminal method
in a thermostatic bath maintained at 20.degree. C. (.+-.0.5.degree.
C.). The distance between the terminals was set to 100 mm.
TABLE-US-00001 TABLE 1 Elements I to be added Alloy No. Co/mass %
Si/mass % Co/Si Example according 1 0.7 0.17 4.12 to this invention
2 1.20 0.30 4.00 3 1.40 0.35 4.00 4 1.65 0.40 4.13 5 1.90 0.45 4.22
Comparative 6 0.30 0.07 4.29 example 7 1.40 0.70 2.00 8 1.40 0.25
5.60 9 3.00 0.75 4.00
TABLE-US-00002 TABLE 2 Solid- Aging Stress relief solution/
annealing/ Rolling annealing/ Process .degree. C. .degree. C. (red
%) .degree. C. A 825 525 20 350 B 850 525 20 350 C 875 525 20 350 D
900 525 20 350 E 925 525 20 350 F 950 525 20 350 G 750 525 20 350 H
1000 525 20 350
TABLE-US-00003 TABLE 3 Alloy No. Steps YS/MPa TS/MPa EC (% IACS) 1
F 550 620 68 2 F 620 660 65 3 F 660 700 60 4 F 670 710 59 5 F 675
715 58 6 F 300 380 75 7 F 620 670 33 8 F 610 650 44 9 Hot-rolling
was difficult, due to excessive precipitation and
crystallization
[0058] In those tests, since only the strength and the electrical
conductivity were evaluated, the treatment temperature of
950.degree. C. (Process F in Table 2 above) was employed, at which
the strength was sufficiently obtained.
[0059] In Alloy Nos. 1 to 5 which satisfy the scope of the
composition defined in the present invention, the alloy materials
were obtained, which were excellent in both of the strength and the
electrical conductivity with a favorable balance.
[0060] Contrary to the above, with regard to Alloy No. 6 which had
too small amounts of Co and Si, the degree of the precipitation
hardening was small, and the strength was insufficient.
[0061] Further, with regard to Alloy No. 9 which had a too large
amount of Co, the production of the alloy material was difficult,
since there occurred a deterioration of the product due to an
excessive formation of oxides upon the melting and reheat cracks of
the ingot due to an excessive precipitation and the like, to make
it difficult to conduct the hot rolling. Further, since a large
amount of expensive Co was used, the alloy material was inferior in
the competitive power in terms of cost.
[0062] In the comparative examples of Alloy Nos. 7 and 8 having the
Co/Si ratios in the range outside of Co/Si=3 to 5, the resultant
alloy materials contained more of solid-solution elements of Co and
Si which did not precipitate, to cause a conspicuous deterioration
in the electrical conductivity.
Example 1
[0063] Alloy materials of Examples 1 to 3 and 10 to 16 according to
the present invention and Comparative examples 1 to 3 and 18 to 22
were obtained in the same manner as in Reference example 1, except
that alloys, composed of the components shown in Table 4 with the
balance of Cu and inevitable impurities, were used, and that the
temperature for the solution treatment was changed to temperatures
of Processes A to H shown in Table 2, respectively. Alloys Nos. 1
to 3 shown in Table 4 had the same compositions as those of Alloys
Nos. 1 to 3 shown in Table 1, respectively. Alloys Nos. 10 to 12 of
Examples shown in Table 4 were those prepared by adding Cr to
Alloys Nos. 1 to 3 shown in Table 1 and Table 4, respectively, in
the amounts within the defined ranges; and Alloys Nos. 13 to 16 of
Examples shown in Table 4 were those prepared by adding Mg (No.
13), Sn (No. 14), Cr and Mg (No. 15), and Cr and Ti (No. 16) to
Alloy No. 3 shown in Table 1 and Table 4, respectively, in the
amounts within the defined ranges. Alloys Nos. 18 to 22 of
Comparative examples shown in Table 4 were those produced by adding
Cr (No. 18), Ti (No. 19), Mg (No. 20), Sn (No. 21), and Zr (No. 22)
to Alloy No. 3 shown in Table 1 and Table 4, respectively, in the
amounts exceeding the defined ranges.
[0064] With respect to the thus-obtained alloy materials of
Examples 1 to 3 and 10 to 16 according to the present invention and
Comparative examples 1 to 3 and 18 to 22, the yield stress (YS),
the tensile strength (TS), and the electrical conductivity (EC)
were measured in the same manner as in Reference example 1.
Further, a grain size (GS) and a bending property (R/t) were
measured, according to the methods described below. The results are
shown in Table 5.
[0065] Method of measuring the grain size: a cross-section
perpendicular to the rolling direction of a test piece was finished
into a mirror surface by wet polishing and buff polishing; the
thus-polished surface was corroded with a liquid of chromic
acid:water=1:1 for several seconds; and then, a photograph of the
resultant polished surface was taken using a secondary electronic
image of SEM at a magnification ratio of 400 to 1,000 times; to
measure an average grain size (.mu.m) on the cross-section,
according to the cutting method of JIS-H-0501. The analysis was
conducted at the cross section transverse to the rolling
direction.
[0066] Evaluation of the bending property: the surface of a sample
with a respective sheet thickness and with a sheet width w of 10
(mm) from the test specimen, was rubbed lightly with metal
polishing powders, to remove an oxide layer, the resultant sample
was subjected to W-bending, such that the inner angle of bending
would be 90.degree., with respect to two kinds of: bending ((GOOD
WAY: hereinafter, also referred to GW)) of the sample parallel to
the rolling direction; and bending (BAD WAY: hereinafter, also
referred to BW) of the sample perpendicular to the rolling
direction. The bending was evaluated with R/t, which was a value
obtained by dividing the smallest bending radius R at which no
micro-cracks occurred, by the sample's sheet thickness t.
TABLE-US-00004 TABLE 4 Elements I to be added Alloy No. Process
Co/mass% Si/mass% Element (s) II to be added Example 1 A 0.7 0.17
None according to this 2 C 1.2 0.3 None invention 3 E 1.4 0.35 None
10 A 0.7 0.17 Cr: 0.1 mass % 11 C 1.2 0.3 Cr: 0.1 mass % 12 E 1.4
0.35 Cr: 0.2 mass % 10 B 0.7 0.17 Cr: 0.1 mass % 11 D 1.2 0.3 Cr:
0.1 mass % 12 F 1.4 0.35 Cr: 0.2 mass % 13 F 1.4 0.35 Mg: 0.2 mass
% 14 F 1.4 0.35 Sn: 0.4 mass % 15 F 1.4 0.35 Cr: 0.2 mass %, Mg:
0.1 mass % 16 F 1.4 0.35 Cr: 0.2 mass %, Ti: 0.5 mass % Comparative
1 B 0.7 0.17 None example 2 F 1.2 0.3 None 3 F 1.4 0.35 None 3 G
1.4 0.35 None 3 H 1.4 0.35 None 18 -- 1.4 0.35 Cr: 1.2 mass % 19 --
1.4 0.35 Ti: 1.2 mass % 20 -- 1.4 0.35 Mg: 1.2 mass % 21 F 1.4 0.35
Sn: 1.2 mass % 22 -- 1.4 0.35 Zr: 1.2 mass %
TABLE-US-00005 TABLE 5 Alloy No. Process YS/MPa TS/MPa EC (% IACS)
GS/.mu.m R/t (GW) R/t (BW) Example 1 A 520 580 70 10 0.4 0.4
according 2 C 550 610 68 10 0.5 0.5 to this 3 E 600 660 65 10 1 1
invention 10 A 535 595 68 5 0.4 0.4 11 C 575 615 66 8 0.5 0.5 12 E
620 672 64 8 1 1.2 10 B 540 600 68 15 0.4 0.4 11 D 590 645 66 18
0.4 0.4 12 F 600 660 65 20 0.6 1 13 F 675 700 58 20 1.2 1.2 14 F
670 710 50 20 1.5 1.5 15 F 677 725 56 15 1.5 1.5 16 F 650 710 55 20
1.5 1.5 Comparative 1 B 530 580 66 50 0.6 0.8 example 2 F 630 680
60 80 0.8 1 3 F 682 720 59 35 1 1.6 3 G 540 580 72 -- 1.5 2 3 H 700
730 55 50 2.5 3 18 -- Production was impossible 19 -- Production
was impossible 20 -- Production was impossible 21 F 578 675 35 20
1.2 1.5 22 -- Production was impossible
[0067] In Examples 1 to 3 according to the present invention in
Table 5, the solution treatment temperature Ts (.degree. C.) was
set at a temperature (.degree. C.) of 800.degree. C. to 960.degree.
C. and lower than -122.77X.sup.2+409.99X+615.74, in which the Co
content (mass %) was represented by X. Thus, the grain size was
able to be maintained at less than 20 .mu.m, and it was possible to
obtain the copper alloy materials, which were excellent in the
balance of the mechanical strength, the electrical conductivity,
and the bending property.
[0068] Specifically, the yield stress was not less than 500 MPa but
less than 650 MPa, the electrical conductivity was 60% IACS or
more, and the values (R/t) representing the bending property were
1.0 or less in both of GW and BW. Further, some of the Examples
according to the present invention had the values (R/t)
representing the bending property of 0.6 or less, or even less than
0.5, in both of GW and BW. Thus, it is found that the copper alloy
materials were obtained, which were excellent in the balance of the
mechanical strength, the electrical conductivity, and the bending
property.
[0069] Contrary to the above, even in the same compositions, when
the samples were subjected to the heat treatments at the
temperatures shown in Comparative examples 1 to 3, the strengths
were equal to or higher than those of Examples 1 to 3 according to
the present invention, but the grain sizes were coarse and they
were poor in the bending property, as compared to Examples 1 to 3
according to the present invention. Further, the value (R/t)
representing the bending property showed a tendency to be poor in
BW, as compared with that in GW.
[0070] As shown in Table 5, in Comparative example 3, the
treatment, which was conducted at a solution temperature lower than
the predetermined temperature, resulted in the remaining of
structures that did not recrystallize (which is shown in Table 5 as
no value (-) of grain size), while the treatment, which was
conducted at a solution temperature higher than the predetermined
temperature, resulted in the coarsening of the grains. Thus, those
cases each failed to attain or maintain the target favorable
bending property.
[0071] In Examples 10 to 16 according to the present invention in
Table 5, one or more of Cr, Mg, Mn, Sn, V, Zn, Al, Fe, Nb, Ni, Ti,
and Zr was added (that is, the element(s) II to be added was added
in the total amount of 0.01 to 1 mass %), and the solution
treatment temperature Ts (.degree. C.) was set at a temperature
(.degree. C.) of 800.degree. C. to 960.degree. C. and lower than
-94.643X.sup.2+329.99X+677.09, in which the Co content (mass %) was
represented by X. Thus, it was possible to control the grain size
to 20 .mu.m or less, by the heat treatment at a temperature as high
as that in Reference example 1, and the copper alloy materials had
the same level of mechanical strength as that in Reference example
1 and were excellent in the bending property.
[0072] Specifically, with respect to the samples which had the
yield stress of not less than 500 MPa but less than 650 MPa and the
electrical conductivity of 60% IACS or more, the values (R/t)
representing the bending property were 1.2 or less in both of GW
and BW. Some of Examples had the values (R/t) representing the
bending property of 1.0 or less, even 0.6 or less, or further even
less than 0.5, in both of GW and BW. Further, with respect to the
samples which had the yield stress of 650 MPa or more and the
electrical conductivity of 50% IACS or more, the values (R/t)
representing the bending property were 1.5 or less, or 1.2 or less,
in both of GW and BW. Thus, it is found that it was possible to
obtain the copper alloy materials, which were excellent in the
balance of the mechanical strength, the electrical conductivity,
and the bending property.
[0073] Further, even in the case where it was possible to control
the grain size to 20 .mu.m or less by adding only Co and Si in the
means of Reference example 1, it was able to accelerate a further
size reduction of the grains by adding any of the above-mentioned
metals, to obtain the excellent bending property.
[0074] Contrary to the above, in Comparative examples 18 to 22 in
which the addition amount of the element II to be added exceeded
1%, due to the formation of oxides upon the casting and excessive
precipitation in the high-temperature heat-treatment, the
productivity was conspicuously deteriorated to make it difficult to
obtain products. Further, in Comparative example 21 in which the
addition amount of the element II to be added exceeded 1%, the
electrical conductivity was conspicuously lowered when the
solid-solution-type elements were added, the yield stress was less
than 650 MPa, but the value of R/t exceeded 1.2 in BW, which means
that the bending property was poor. Further the value (R/t)
representing the bending property showed a tendency to be poor in
BW, as compared to that in GW.
INDUSTRIAL APPLICABILITY
[0075] The copper alloy material for electric/electronic parts of
the present invention can be favorably used in electric/electronic
parts, such as connectors, terminal materials, and the like, for
electric/electronic equipments, and particularly in high-frequency
relays or switches that are required to have a high electrical
conductivity, or connectors, terminal materials, and lead frames,
to be mounted on vehicles or the like.
[0076] Having described our invention as related to the present
embodiments, it is our intention that the invention not be limited
by any of the details of the description, unless otherwise
specified, but rather be construed broadly within its spirit and
scope as set out in the accompanying claims.
[0077] This non-provisional application claims priority under 35
U.S.C. .sctn.119 (a) on Patent Application No. 2008-074650 filed in
Japan on Mar. 21, 2008, of which is entirely herein incorporated by
reference.
* * * * *