U.S. patent application number 11/758830 was filed with the patent office on 2008-03-06 for copper alloy and method of producing same.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. Invention is credited to Takefumi ITO, Yumiko Iwashita, Toshikazu Kawahata, Toshihiro Kurita, Takayuki Nagai.
Application Number | 20080056930 11/758830 |
Document ID | / |
Family ID | 39079012 |
Filed Date | 2008-03-06 |
United States Patent
Application |
20080056930 |
Kind Code |
A1 |
ITO; Takefumi ; et
al. |
March 6, 2008 |
COPPER ALLOY AND METHOD OF PRODUCING SAME
Abstract
To obtain a copper alloy having a tensile strength of 700
N/mm.sup.2 or more and a conductivity of 60% IACS or more, a copper
alloy of the present invention comprises from 0.8 mass % to 1.8
mass % of Co, from 0.16 mass % to 0.6 mass % of Si, and the balance
of Cu and unavoidable impurities, in which a mass ratio of Co to Si
(Co/Si) is between 3.0 and 5.0; a size of inclusions to be
precipitated in the copper alloy is 2 .mu.m or less; and a total
volume of the inclusions having a size of between 0.05 .mu.m and 2
.mu.m in the copper alloy is 0.5 vol % or less.
Inventors: |
ITO; Takefumi; (Tokyo,
JP) ; Kawahata; Toshikazu; (Kanagawa, JP) ;
Iwashita; Yumiko; (Kanagawa, JP) ; Kurita;
Toshihiro; (Kanagawa, JP) ; Nagai; Takayuki;
(Tokyo, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Chiyoda-ku
JP
MITSUBISHI ELECTRIC METECS CO., LTD.
Sagamihara-shi
JP
|
Family ID: |
39079012 |
Appl. No.: |
11/758830 |
Filed: |
June 6, 2007 |
Current U.S.
Class: |
420/477 ;
148/554; 420/490 |
Current CPC
Class: |
C22C 9/06 20130101; H01B
1/026 20130101 |
Class at
Publication: |
420/477 ;
148/554; 420/490 |
International
Class: |
C22C 9/00 20060101
C22C009/00; C22F 1/08 20060101 C22F001/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2006 |
JP |
2006-233962 |
Claims
1. A copper alloy comprising from 0.8 mass % to 1.8 mass % of Co,
from 0.16 mass % to 0.6 mass % of Si, and the balance of Cu and
unavoidable impurities, wherein a mass ratio of Co to Si (Co/Si) is
between 3.0 and 5.0; a size of inclusions to be precipitated in the
copper alloy is 2 .mu.m or less; and a total volume of the
inclusions having a size of between 0.05 .mu.m and 2 .mu.m in the
copper alloy is 0.5 vol % or less.
2. A copper alloy according to claim 1, further comprising from 0.1
mass % to 1.0 mass % of Zn.
3. A copper alloy according to claim 1, further comprising from
0.01 mass % to 0.2 mass % of one or more elements selected from the
group consisting of Fe, Ni, P, Sn, Mg, Zr, Cr, and Mn in total.
4. A copper alloy according to claim 1, wherein the copper alloy
has an O2 content of 10 ppm or less and an H2 content of 1 ppm or
less.
5. A method of producing a copper alloy, comprising the steps of:
(a) melting a copper alloy raw material including from 0.8 mass %
to 1.8 mass % of Co, from 0.16 mass % to 0.6 mass % of Si, and the
balance of Cu and unavoidable impurities and having a mass ratio of
Co to Si (Co/Si) is between 3.0 and 5.0 to form an ingot, and
rolling the ingot; (b) carrying out solution treatment involving
heating the rolled material to between 700.degree. C. and
1,000.degree. C. and quenching; (c) carrying out aging treatment by
heating an alloy material subjected to the solution treatment at
between 400.degree. C. and 600.degree. C. for 2 hours to 8 hours;
(d) cooling the alloy material subjected to the aging treatment to
at least 380.degree. C. at a cooling rate of between 10.degree.
C./h and 50.degree. C./h; and (e) finishing the cooled alloy
material by cold rolling.
6. A method of producing a copper alloy according to claim 5,
wherein the copper alloy raw material further comprises from 0.1
mass % to 1.0 mass % of Zn.
7. A method of producing a copper alloy according to claim 5,
wherein the copper alloy raw material further comprises from 0.01
mass % to 0.2 mass % of one or more elements selected from the
group consisting of Fe, Ni, P, Sn, Mg, Zr, Cr, and Mn in total.
8. A method of producing a copper alloy according to claim 5,
wherein the copper alloy raw material has an O.sub.2 content of 10
ppm or less and an H.sub.2 content of 1 ppm or less.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a copper alloy and to a
method of producing same. In particular, the present invention
relates to a copper alloy used for electronic components and to a
method of producing same.
[0003] 2. Description of the Related Art
[0004] In lead frames having integrated circuits (IC) mounted
thereon, connector terminals to be used in electronic devices, or
the like, reductions in thickness of the lead frame and increases
in the number of pins and reductions in terminal pitch have
progressed with the miniaturization and multifunctionalization of
the devices to be used and with increases in packaging surface
density. For these reasons, there is an increasing demand for
reliable connections in packaging of electronic components.
[0005] That is, a metal material used for such electronic
components must have further improved strength because
miniaturization of electronic components leads to reductions in
thickness. Further, the metal material must have further improved
conductivity because increases in the number of pins and reductions
in pitch lead to reductions in sectional area.
[0006] As a metal material used for electronic components having
high strength and high conductivity, an alloy material containing
beryllium (Be) added to copper (Cu) is conventionally known. Among
these alloy materials, there are some having a high tensile
strength of 800 N/mm.sup.2 or more and a high conductivity of 50%
IACS (International Annealed Copper Standard) or more.
[0007] However, in consideration of recent environmental issues,
use of an alloy material containing Be is now being avoided. Thus,
copper alloys replacing such alloy materials have been attracting
attention.
[0008] Of the copper alloys, a Cu--Co--Si-based alloy is known to
be a precipitation hardened alloy in which a fine Co.sub.2Si
intermetallic compound is dispersed and precipitated in Cu and
serves as a barrier against transformation to provide further
improved strength and conductivity. It is reported that strength
and conductivity can be further improved by adjusting addition
amounts of Co and Si and further adding trace amounts of
additives.
[0009] An example of the conventional Cu--Co--Si-based alloy is a
copper alloy used for lead frames containing from 0.4 wt % to 1.6
wt % of Co, from 0.1 wt % to 0.5 wt % of Si, the balance of Cu and
unavoidable impurities and further containing from 0.05 wt % to 1.0
wt % of Zn and from 0.0005 wt % to 0.1 wt % of at least one element
selected from the group consisting of Ca, Y, rare earth elements,
Ti, Zr, Hf, V, and Nb (see JP 2-277735 A, for example).
[0010] Another example thereof is a copper alloy used for
electronic and electric components containing from 0.1 wt % to 3.0
wt % of Co, from 0.3 wt % to 1.0 wt % of Si, from 0.3 wt % to 1.0
wt % of Zn, from 0.005 wt % to 0.1 wt % of Mn, from 0.005 wt % to
0.1 wt % of P, the balance of Cu and unavoidable impurities,
containing a compound of Co and Si and a compound of Co and P in a
parent phase, having an average grain size of the parent phase of
20 .mu.m or less, and having an aspect ratio in a thickness
direction with respect to a rolling direction of between 1 and 3
(see JP 9-20943 A, for example).
[0011] However, in conventional copper alloys, addition amounts of
Co, Si, and other elements and a Co/Si ratio may not be optimized
and the copper alloy may not have an appropriate structure. Thus,
no conventional copper alloy has excellent strength and
conductivity. For example, studies have been conducted on the
composition of the copper alloy in JP 2-277735 A and JP 9-20943 A,
but no studies have been conducted on inclusions to be precipitated
in the copper alloy. Thus, copper alloys have problems in that they
have no appropriate structure and either strength or conductivity
for example, is not sufficient. As a result, conventional copper
alloys cannot satisfy a tensile strength of 700 N/mm.sup.2 or more
and a conductivity of 60% IACS or more at the same time.
SUMMARY OF THE INVENTION
[0012] The present invention has been made in view of solving the
problems as described above, and an object of the present invention
is to provide a copper alloy having excellent strength and
conductivity, in particular, a copper alloy having a tensile
strength of 700 N/mm.sup.2 or more and a conductivity of 60% IACS
or more.
[0013] Another object of the present invention is to provide a
method of producing a copper alloy having the properties as
described above.
[0014] The inventors of the present invention have conducted
extensive studies for solving the problems as described above, and
have conceived that the composition of a copper alloy and the size
and total amounts of inclusions to be precipitated in the copper
alloy are optimized to optimize a structure of the copper alloy.
Thus, the inventors have completed the present invention.
[0015] That is, the present invention provides a copper alloy
comprising from 0.8 mass % to 1.8 mass % of Co, from 0.16 mass % to
0.6 mass % of Si, and the balance of Cu and unavoidable impurities,
in which a mass ratio of Co to Si (Co/Si) is between 3.0 and 5.0;
size of inclusions to be precipitated in the copper alloy is 2
.mu.m or less; and total volume of the inclusions having a size of
between 0.05 .mu.m and 2 .mu.m in the copper alloy is 0.5 vol % or
less.
[0016] Further, the present invention provides a method of
producing a copper alloy including the steps of: (a) melting a
copper alloy raw material including from 0.8 mass % to 1.8 mass %
of Co, from 0.16 mass % to 0.6 mass % of Si, and the balance of Cu
and unavoidable impurities and having a mass ratio of Co to Si
(Co/Si) is between 3.0 and 5.0 to form an ingot, and rolling the
ingot; (b) carrying out solution treatment involving heating the
rolled material to between 700.degree. C. and 1,000.degree. C. and
quenching; (c) carrying out aging treatment by heating an alloy
material subjected to the solution treatment at between 400.degree.
C. and 600.degree. C. for 2 hours to 8 hours; (d) cooling the alloy
material subjected to the aging treatment to at least 380.degree.
C. at a cooling rate of between 10.degree. C./h and 50.degree.
C./h; and (e) finishing the cooled alloy material by cold
rolling.
[0017] According to the present invention, an optimum precipitated
amount of a Co.sub.2Si compound may be included in the copper
alloy, and contents of Co and Si elements remained in a solid
solution state may be reduced. Thus, a copper alloy having
excellent strength and conductivity, in particular, a copper alloy
having a tensile strength of 700 N/mm.sup.2 or more and a
conductivity of 60% IACS or more can be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In the accompanying drawings:
[0019] FIG. 1 is a flow chart illustrating a method of producing a
copper alloy of the present invention; and
[0020] FIG. 2 is a graph showing a relationship between tensile
strength and conductivity of copper alloys obtained in Examples 1
and 2 and Comparative Examples 1 and 2.
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
(Copper Alloy)
[0021] A copper alloy of the present invention is comprised of from
0.8 mass % to 1.8 mass % of Co, from 0.16 mass % to 0.6 mass % of
Si, and the balance of Cu and unavoidable impurities. In a case
where Co content is less than 0.8 mass % or Si content is less than
0.16 mass %, a sufficient amount of a Co.sub.2Si compound is not
formed and desired strength and conductivity cannot be obtained. In
contrast, in the case where the Co content is more than 1.8 mass %
or the Si content is more than 0.6 mass %, an excess amount of a
Co--Si compound phase or a Cu--Co--Si alloy phase is precipitated
and desired strength and conductivity cannot be obtained.
[0022] Further, a mass ratio of Co to Si (Co/Si) is within a range
of between 3.0 and 5.0. In the case where the mass ratio is less
than 3.0 or more than 5.0, an excess amount of a Co--Si compound
phase or a Cu--Co--Si alloy phase excluding the Co.sub.2Si compound
is precipitated and desired strength and conductivity cannot be
obtained.
[0023] The unavoidable impurities in the present invention refer to
substances included in a general base metal or impurities mixed
into the copper alloy during production, and examples thereof
include As, Sb, Bi, Pb, S, Fe, O.sub.2, and H.sub.2. Of these, from
the viewpoint of improving plating adhesion and soldering
properties, the copper alloy of the present invention preferably
has an O.sub.2 content of 10 ppm or less and an H.sub.2 content of
1 ppm or less. In cases where O.sub.2 content is more than 10 ppm,
the plating adhesion and soldering properties may degrade. In cases
where H.sub.2 content is more than 1 ppm, the plating adhesion and
soldering properties may degrade.
[0024] Further, inclusions are precipitated in the copper alloy of
the present invention, and size of the inclusions is 2 .mu.m or
less. In cases where the size of the inclusions is more than 2
.mu.m, desired strength cannot be obtained and the plating adhesion
degrades.
[0025] The inclusions in the present invention refer to bulky
precipitated particles formed during production of the copper
alloy. To be specific, inclusions refer to particles of oxides
formed through reaction with the atmosphere or particles of
undesired Co--Si compound phases or Cu--Co--Si alloy phases
excluding the fine Co.sub.2Si compound.
[0026] The size of the inclusions refers to diameter of the
inclusions if the inclusions are spherical and refers to a shorter
diameter or shorter side of the inclusions if the inclusions are
elliptical or rectangular.
[0027] In the copper alloy of the present invention, total volume
of the inclusions having a size of between 0.05 .mu.m and 2 .mu.m
in the copper alloy is 0.5 vol % or less. In the case where the
total volume of the inclusions is more than 0.5 vol %, desired
strength cannot be obtained and the plating adhesion degrades.
[0028] Volume ratio of the inclusions in the copper alloy of the
present invention can be determined by polishing a section of the
copper alloy of the present invention and observing the polished
surface with a scanning electron microscope. The volume ratio of
the inclusions can be determined by specifying an observation
region of this case as a region at a predetermined depth (for
example, about 1 .mu.m) or more from an uppermost surface of a
sample, integrating the total area of the inclusions in the
observation region through image processing, and determining the
total area by the observation region. To be specific, five
arbitrary observation regions of about 100.times.100 .mu.m are
observed, and an average value of area ratios of the inclusions in
each observation region is referred to as the volume ratio of the
inclusions.
[0029] The copper alloy of the present invention may contain Zn
from the viewpoint of improving plating adhesion. Zn has an effect
of suppressing interfacial peeling due to change over time after Sn
(tin) plating and Sn alloy plating. Zn content is preferably from
0.1 mass % to 1.0 mass %. Zn content within the above range can
improve the plating adhesion without degrading the strength and
conductivity of the copper alloy. In cases where the Zn content is
less than 0.1 mass %, the effects of improving the plating adhesion
through Zn addition may not be obtained. In contrast, in cases
where the Zn content is more than 1.0 mass %, the conductivity may
degrade.
[0030] The copper alloy of the present invention may contain one or
more elements selected from the group consisting of Fe, Ni, P, Sn,
Mg, Zr, Cr, and Mn from the viewpoint of further improving the
strength. Of those, Fe and Ni are more preferred because the
elements each have an effect of improving bending workability
through formation of fine crystal grains. Content of the elements
is preferably from 0.01 mass % to 0.2 mass % in total. In cases
where the content of the elements is less than 0.01 mass %, the
effects of improving strength through addition of the elements may
not be obtained. In contrast, in cases where the content of the
elements is more than 0.2 mass %, the conductivity may degrade.
(Method of Producing Copper Alloy)
[0031] In a conventional method of producing a copper alloy, an
ingot obtained by melting and casting a copper alloy raw material
is subjected to hot rolling, then to cold rolling, and the like,
thereby forming lattice defects in the copper alloy.
[0032] For example, in a method of producing a copper alloy in JP
2-277735 A, a copper alloy raw material is melted and cast in a
mold to obtain an ingot having desired dimensions. The ingot is
subjected to hot rolling at 950.degree. C. and then water cooled
immediately. Then, a surface of the hot rolled plate is subjected
to milling, to cold rolling to a desired thickness, and then the
resultant is subjected to heat treatment at 500.degree. C. for 1
hour, subjected to rolling to a desired thickness again, and
subjected to stress relief annealing at 300.degree. C. for 1
hour.
[0033] In a method of producing a copper alloy in JP 9-20943 A, a
copper alloy raw material is melted and cast to obtain an ingot
having desired dimensions. Then, the ingot is maintained at
980.degree. C. for 3 hours, subjected to hot rolling, and subjected
to milling or pickling and buffing, to thereby obtain desired
dimensions. Next, the resultant is subjected to cold rolling at 85%
or more, annealing at between 450.degree. C. and 480.degree. C. for
5 minutes to 30 minutes, cold rolling at 30% or less, and aging
treatment at between 450.degree. C. and 500.degree. C. for 30
minutes to 120 minutes.
[0034] Meanwhile, the inventors of the present invention have
conducted extensive studies on a method of producing a copper alloy
having the properties as described above. As a result, the
inventors of the present invention have found that introduction of
lattice defects through cold rolling or the like after hot rolling
is not important and cooling of the copper alloy subjected to the
aging treatment to at least 380.degree. C. at a cooling rate of
between 10.degree. C./h and 50.degree. C./h is important for
improving the strength and conductivity of the copper alloy.
[0035] To be more specific, the inventors of the present invention
have found that sufficient lattice defects are introduced into the
copper alloy through quenching after solution treatment, and
additional introduction of strain through cold rolling or the like
is not needed. Meanwhile, through trials, the inventors of the
present invention have found that control of the cooling rate at
between 10.degree. C./h and 50.degree. C./h after the aging
treatment without cold rolling or the like provides effects of
precipitating a sufficient amount of the Co.sub.2Si compound and
preventing residual strain remaining in the copper alloy.
[0036] That is, the method of producing a copper alloy of the
present invention includes the steps of: (a) melting a copper alloy
raw material including from 0.8 mass % to 1.8 mass % of Co, from
0.16 mass % to 0.6 mass % of Si, and the balance of Cu and
unavoidable impurities and having a mass ratio of Co to Si (Co/Si)
of between 3.0 and 5.0 to form an ingot, and rolling the ingot; (b)
carrying out solution treatment involving heating the rolled
material to between 700.degree. C. and 1,000.degree. C. and
quenching; (c) carrying out aging treatment by heating an alloy
material subjected to the solution treatment at between 400.degree.
C. and 600.degree. C. for 2 hours to 8 hours; (d) cooling the alloy
material subjected to the aging treatment to at least 380.degree.
C. at a cooling rate of between 10.degree. C./h and 50.degree.
C./h; and (e) finishing the cooled alloy material by cold
rolling.
[0037] In step (a), the copper alloy raw material may further
contain from 0.1 mass % to 1.0 mass % of Zn from the viewpoint of
improving the plating adhesion. The reasons for the mixing amount
are described above.
[0038] The copper alloy material may further contain from 0.01 mass
% to 0.2 mass % of one or more elements selected from the group
consisting of Fe, Ni, P, Sn, Mg, Zr, Cr, and Mn in total from the
viewpoint of further improving the strength. The reasons for the
mixing amount are described above.
[0039] The copper alloy raw material may have an O.sub.2 content of
10 ppm or less and an H.sub.2 content of 1 ppm or less from the
viewpoint of improving the plating adhesion and soldering
properties. The reasons for the contents are described above. A
method of reducing the O.sub.2 and H.sub.2 contents in the copper
alloy raw material is not particularly limited, and a conventional
method may be employed. An example of the method includes: methods
involving using a deoxidizing agent such as calcium boride; and
methods involving bubbling treatment by using argon gas, nitrogen
gas, or the like.
[0040] The method of melting the copper alloy raw material is not
particularly limited. The method may involve heating the copper
alloy raw material to a melting temperature or higher by using a
conventional device such as a high frequency melting furnace. The
method of casting or rolling is not particularly limited, and the
method may be carried out according to conventional methods.
[0041] Note that during step (a), milling may be conducted after
the ingot is formed from the viewpoint of removing scales of the
ingot. Further, after step (a), annealing may be conducted from the
viewpoints of softening the alloy to improve workability, and the
like. Methods of milling and annealing are not particularly
limited, and the methods may be carried out according to
conventional methods.
[0042] The solution treatment in step (b) involves heating of the
rolled material to between 700.degree. C. and 1,000.degree. C. and
quenching the resultant. Heating time is preferably between 1
minute and 60 minutes. A heating temperature and heating time
within the above ranges allow favorable formation of a solid
solution of alloy elements. Methods of heating and quenching are
not particularly limited, and the methods may be carried out
according to conventional methods.
[0043] The aging treatment in step (c) involves heating of the
alloy raw material subjected to the solution treatment at between
400.degree. C. and 600.degree. C. for 2 hours or more and 8 hours
or less. A heating temperature and heating time within the above
ranges can provide a fine Co.sub.2Si compound in a precipitated
state. Heating methods are not particularly limited, and the method
may be carried out according to conventional methods.
[0044] Step (d) involves cooling of the alloy raw material
subjected to the aging treatment to at least 380.degree. C. at a
cooling rate of between 10.degree. C./h and 50.degree. C./h.
[0045] A cooling rate within the above range allows sufficient
amount of the Co.sub.2Si compound to be precipitated and prevents
residual strain remaining in the copper alloy. In cases where the
cooling rate is less than 10.degree. C./h, the Co.sub.2Si compound
increases in size and desired strength cannot be obtained. In
contrast, in cases where the cooling rate is more than 50.degree.
C./h, residual strain remains in the copper alloy and the amount of
the Co.sub.2Si compound that precipitates are reduced due to the
strain, so the Co and Si remain as they are in a solid solution
state. Thus, desired strength and conductivity cannot be
obtained.
[0046] In cases where the cooling temperature is higher than
380.degree. C., an appropriate structure of the copper alloy cannot
be obtained and desired strength and conductivity cannot be
obtained. Note that after the cooling temperature reaches
380.degree. C., since the structure of the copper alloy does not
change drastically through the cooling process thereafter, the
lower limit of the cooling temperature is not particularly limited.
However, from the viewpoint of stably obtaining a copper alloy
having an appropriate structure, the alloy raw material is
preferably cooled to 350.degree. C. at a cooling rate of between
10.degree. C./h and 50.degree. C./h.
[0047] Step (e) involves cold rolling of the alloy raw material for
finishing into a copper alloy having a desired size. The methods of
cold rolling are not particularly limited, and the method may be
carried out according to conventional methods. After step (e), low
temperature annealing may be conducted from the viewpoint of stress
relieving of the copper alloy. The method of low temperature
annealing is not particularly limited, and the method may be
carried out according to conventional methods.
[0048] The copper alloy to be obtained by the production method as
described above is capable of suppressing increase in size of the
Co.sub.2Si compound to be precipitated in the copper alloy and
precipitating a sufficient amount of the fine Co.sub.2Si compound,
and thus has excellent strength and conductivity.
EXAMPLES
[0049] Hereinafter, the present invention will be described
specifically with reference to the examples, but the present
invention is not limited to the following examples.
[0050] The following properties of copper alloys obtained in the
Examples and Comparative Examples were evaluated through the
following procedures.
(1) Tensile Strength
[0051] The tensile strength was evaluated at room temperature in
accordance with JIS Z2241.
(2) Conductivity
[0052] The conductivity was evaluated at room temperature in
accordance with JIS H0505.
(3) Plating Adhesion
[0053] The plating adhesion was evaluated by: subjecting a copper
alloy to Sn electroplating to a thickness of 3 .mu.m; heating the
copper alloy at 105.degree. C. for 500 hours (500 hours and 1,000
hours in Example 4 alone); conducting a bending and unbending test
at 180.degree.; and visually observing a sample surface. In the
evaluation: a sample having a plated film without any damage is
indicated by .largecircle.; a sample having an unpeeled plated film
with damage observed is indicated by .DELTA.; and a sample having a
peeled plated film is indicated by X.
(4) Bending Workability
[0054] The bending workability was evaluated in accordance with JIS
Z2248 by conducting a V-bending test at 90.degree. at a bending
radius of 0.3 mm and observing a bent end surface with an optical
microscope. In the evaluation: a sample having no wrinkles is
indicated by A; a sample having small wrinkles is indicated by B; a
sample having large wrinkles is indicated by C; a sample having
small cracks is indicated by D; and a sample having large cracks is
indicated by E.
(5) Soldering Property
[0055] The soldering property was evaluated by: applying flux to a
copper alloy subjected to pickling; immersing the resultant in
solder consisting of 60 mass % of Sn and 40 mass % of Pb at
235.degree. C. for 5 seconds; and visually observing a sample
surface after pulling the sample out. In the evaluation: a sample
having uniform and wet solder on a surface is indicated by
.largecircle.; a sample having wet but non-uniform solder with
unevenness on a surface is indicated by .DELTA.; and a sample
having solder with a non-wet part on a surface is indicated by
X.
Example 1
[0056] In Example 1, copper alloys (Products 1 to 3 of the present
invention) each containing Cu, Co, Si, and unavoidable impurities
in a predetermined ratio were produced following the flow chart
shown in FIG. 1. Note that a Cu amount was clarified, but the Cu
amount can obviously be estimated from amounts of other components
shown. Hereinafter, detailed description will be given of a method
of producing a copper alloy by using the flow chart.
[0057] First, copper alloy raw materials (such as Cu, Co, and Si)
satisfying a composition ratio shown in Table 1 were prepared. The
copper alloy raw materials were melted in a high frequency melting
furnace and cast into a plate-like ingot having a thickness of 10
mm (step S1).
[0058] Next, milling was conducted for removing scale on an ingot
surface (step S2).
[0059] Then, the ingot was subjected to rolling at room
temperature, annealing at 800.degree. C., and rolling at room
temperature again, to thereby obtain a sheet having a thickness of
0.38 mm (step S3).
[0060] Then, the sheet was heated at 950.degree. C. for 2 minutes
and cooled in water for solution treatment (step S4).
[0061] The sheet was heated at 500.degree. C. for 4 hours for aging
treatment (step S5).
[0062] Then, the sheet was cooled to 380.degree. C. at a cooling
rate (to be specific, at the respective cooling rates shown in
Table 1) of between 10.degree. C./h and 50.degree. C./h (step
S6).
[0063] Then, the sheet was subjected to cold rolling (finish
rolling), to thereby obtain a copper alloy having a thickness of
0.3 mm (step S7).
[0064] Note that the final cold working rate in Example 1 was
21%.
Example 2
[0065] In Example 2, copper alloys (Products 4 to 7 of the present
invention) each containing Cu, Co, Si, Zn, and unavoidable
impurities in a predetermined ratio were produced according to the
flow chart shown in FIG. 1.
[0066] The production conditions of Example 2 were the same as
those of Example 1. Note that the final cold working rate in
Example 2 was 21%.
Comparative Example 1
[0067] In Comparative Example 1, copper alloys (Comparative
Products 1 to 4) each containing Cu, Co, Si, and unavoidable
impurities in a composition ratio departing from a predetermined
range were produced according to the flow chart shown in FIG.
1.
[0068] The production conditions of Comparative Example 1 were the
same as those of Example 1. Note that the final cold working rate
in Comparative Example 1 was 21%.
Comparative Example 2
[0069] In Comparative Example 2, a copper alloy (Comparative
Product 5) containing Cu, Co, Si, Zn, and unavoidable impurities in
a predetermined ratio and produced by cooling at a cooling rate of
5.degree. C./h after the aging treatment was produced according to
the flow chart shown in FIG. 1.
[0070] The production conditions of Comparative Example 2 were the
same as those of Example 1 except that the cooling rate after the
aging treatment was changed to 5.degree. C./h. Note that the final
cold working rate in Comparative Example 2 was 21%.
[0071] Table 1 shows evaluation results of the tensile strength,
conductivity, and plating adhesion of the copper alloys obtained in
Examples 1 and 2 and Comparative Examples 1 and 2. FIG. 2 shows a
relationship between the tensile strength and conductivity of the
copper alloys.
TABLE-US-00001 TABLE 1 Cooling rate Inclusion Maximum Tensile
Sample Composition (mass %) after aging volume ratio inclusion size
strength Conductivity Plating Kind number Co Si Zn Co/Si (.degree.
C./h) (%) (.mu.m) (N/mm.sup.2) (% IACS) adhesion Present invention
1 0.81 0.17 4.8 30 0.4 0.6 700 62 .DELTA. product 2 1.24 0.29 4.3
30 0.3 0.5 702 61 .largecircle. 3 1.78 0.58 3.1 10 0.5 0.6 710 60
.DELTA. 4 128 0.29 0.5 4.4 30 0.4 0.5 700 61 .largecircle. 5 1.24
0.28 1.0 4.3 30 0.4 0.5 702 60 .largecircle. 6 1.28 0.29 0.5 4.4 10
0.4 0.6 706 62 .largecircle. 7 1.28 0.29 0.5 4.4 50 0.4 0.5 700 60
.largecircle. Comparative 1 0.60 0.55 1.1 30 0.4 0.5 565 58
.largecircle. Example 2 2.00 0.60 3.3 30 0.8 2.5 687 55 X 3 0.80
0.14 5.7 30 0.3 0.5 560 63 .largecircle. 4 1.80 0.75 2.4 30 0.8 0.5
700 56 .DELTA. 5 1.28 0.29 0.5 4.4 5 0.7 4.5 682 60 .DELTA.
[0072] Table 1 and FIG. 2 reveal that the copper alloys of Products
1 to 7 of the present invention each had a maximum inclusion size
of 2 .mu.m or less, a volume ratio of the inclusion of 0.5 vol % or
less, a tensile strength of 700 N/mm.sup.2 or more, and a
conductivity of 60% IACS or more.
[0073] The copper alloy of Product 2 of the present invention had
favorable plating adhesion even though the alloy contained no Zn.
Note that in the copper alloys of Products 1 to 3 of the present
invention, plated films did not peel off.
[0074] The copper alloys of Products 4 to 7 of the present
invention each contained Zn and thus had favorable plating
adhesion.
[0075] Meanwhile, the copper alloys of Comparative Products 1 and 3
each had insufficient amounts of Co or Si. Thus, a sufficient
amount of Co.sub.2Si compound was not precipitated, and desired
tensile strength was not obtained.
[0076] The copper alloy of Comparative Product 2 had too great an
amount of Co. An undesired compound phase was formed due to excess
Co, and the amount and size of inclusions increased. Thus, desired
strength and conductivity were not obtained and plating adhesion
was poor. Similarly, the copper alloy of Comparative Product 4 had
too great an amount of Si. An undesired compound phase was formed
due to excess Si, and desired conductivity was not obtained.
[0077] The copper alloy of Comparative Product 5 had too slow a
cooling rate after the aging treatment. The maximum size of
inclusions increased to 4.5 .mu.m and the volume ratio thereof
increased to 0.7%. Thus, desired tensile strength was not
obtained.
Example 3
[0078] In Example 3, copper alloys (Products 8 to 38 of the present
invention) each containing Cu, Co, Si, Zn, and unavoidable
impurities and one or more elements selected from the group
consisting of Fe, Ni, P, Sn, Mg, Zr, Cr, and Mn in a predetermined
ratio were produced following the flow chart shown in FIG. 1. The
production conditions of Example 3 were the same as those of
Example 1 except that the composition ratio shown in Table 2 was
used and the cooling rate was changed to 30.degree. C./h. Note that
the final cold working rate in Example 3 was 21%.
[0079] Table 2 shows the evaluation results of the tensile
strength, conductivity, plating adhesion, and bending workability
of the copper alloys obtained in Example 3.
TABLE-US-00002 TABLE 2 Sample Composition (mass %) Kind number Co
Si Zn Fe Ni P Sn Mg Zr Cr Mn Co/Si Present invention product 8 1.24
0.29 0.5 0.007 4.3 9 1.24 0.30 0.5 0.01 4.1 10 1.27 0.29 0.5 0.2
4.4 11 1.24 0.28 0.5 0.006 4.4 12 1.24 0.29 0.5 0.01 4.3 13 1.24
0.30 0.5 0.2 4.1 14 1.25 0.29 0.5 0.006 4.3 15 1.25 0.30 0.5 0.01
4.2 16 1.24 0.29 0.5 0.2 4.3 17 1.24 0.27 0.5 0.008 4.6 18 1.27
0.28 0.5 0.01 4.5 19 1.23 0.28 0.5 0.2 4.4 20 1.26 0.29 0.5 0.006
4.3 21 1.24 0.29 0.5 0.01 4.3 22 1.24 0.30 0.5 0.2 4.1 23 1.24 0.30
0.5 0.006 4.1 24 1.26 0.30 0.5 0.01 4.2 25 1.26 0.27 0.5 0.2 4.7 26
1.23 0.31 0.5 0.006 4.0 27 1.29 0.31 0.5 0.01 4.2 28 1.24 0.30 0.5
0.2 4.1 29 1.23 0.27 0.5 0.007 4.6 30 1.25 0.30 0.5 0.01 4.2 31
1.25 0.28 0.5 0.2 4.5 32 1.25 0.29 0.5 0.15 0.05 4.3 33 1.24 0.29
0.5 0.1 0.05 4.3 34 1.27 0.29 0.5 0.1 0.05 4.4 35 1.26 0.27 0.5 0.1
0.1 4.7 36 1.26 0.28 0.5 0.1 0.05 0.05 4.5 37 1.26 0.28 0.5 0.1
0.05 0.05 4.5 38 1.24 0.29 0.5 0.1 0.05 0.05 4.3 Inclusion Maximum
Volume inclusion Tensile Sample ratio size strength Conductivity
Plating Bending Kind number (%) (.mu.m) (N/mm.sup.2) (% IACS)
adhesion workability Present invention product 8 0.4 0.5 700 60
.largecircle. B 9 0.4 0.5 703 61 .largecircle. A 10 0.4 0.5 710 60
.largecircle. A 11 0.4 0.5 701 60 .largecircle. B 12 0.4 0.5 704 61
.largecircle. A 13 0.4 0.5 712 60 .largecircle. A 14 0.4 0.5 701 60
.largecircle. B 15 0.4 0.5 705 61 .largecircle. B 16 0.4 0.5 711 60
.largecircle. B 17 0.4 0.5 700 60 .largecircle. B 18 0.4 0.5 705 60
.largecircle. B 19 0.4 0.5 713 60 .largecircle. B 20 0.4 0.5 700 60
.largecircle. B 21 0.4 0.5 704 61 .largecircle. B 22 0.4 0.5 712 60
.largecircle. B 23 0.4 0.5 701 60 .largecircle. B 24 0.4 0.5 703 60
.largecircle. B 25 0.4 0.5 710 60 .largecircle. B 26 0.4 0.5 700 60
.largecircle. B 27 0.4 0.5 705 60 .largecircle. B 28 0.4 0.5 715 60
.largecircle. B 29 0.4 0.5 700 60 .largecircle. B 30 0.4 0.5 703 61
.largecircle. B 31 0.4 0.5 713 60 .largecircle. B 32 0.4 0.5 714 60
.largecircle. A 33 0.4 0.5 710 60 .largecircle. A 34 0.4 0.5 712 60
.largecircle. B 35 0.4 0.5 712 61 .largecircle. B 36 0.4 0.5 715 60
.largecircle. B 37 0.4 0.5 711 60 .largecircle. A 38 0.4 0.5 710 60
.largecircle. A
[0080] Table 2 reveals that the copper alloys of Products 8 to 38
of the present invention each had a maximum inclusion size of 2
.mu.m or less, an inclusion volume ratio of 0.5 vol % or less, a
tensile strength of 700 N/mm.sup.2 or more, and a conductivity of
60% IACS or more.
[0081] The copper alloys of Products 8 to 38 of the present
invention each contained Zn and thus had favorable plating
adhesion.
[0082] The copper alloys of Products 9-10, 12-13, 32-33 and 37-38
of the present invention each had fine crystal grains through
addition of a predetermined amount of Fe or Ni, and thus had
excellent bending workability.
Example 4
[0083] In Example 4, a copper alloy (Product 39 of the present
invention) containing Cu, Co, Si, and unavoidable impurities in a
predetermined ratio and having an O.sub.2 content of 10 ppm or less
and an H2 content of 1 ppm or less, a copper alloy (Product 40 of
the present invention) containing Cu, Co, Si, and unavoidable
impurities in a predetermined ratio and having an O.sub.2 content
of more than 10 ppm and an H.sub.2 content of 1 ppm or less, and a
copper alloy (Product 41 of the present invention) containing Cu,
Co, Si, and unavoidable impurities in a predetermined ratio and
having an O.sub.2 content of more than 10 ppm and an H.sub.2
content of more than 1 ppm were produced according to the flow
chart shown in FIG. 1. The production conditions of Product 39 of
the present invention were the same as those of Example 1 except
that degassing was conducted by blowing an Ar gas into a molten
liquid containing melted raw materials. The production conditions
of Products 40 and 41 of the present invention were the same as
those of Example 1. Note that the final cold working rate in
Example 4 was 21%.
[0084] Table 3 shows the evaluation results of the tensile
strength, conductivity, plating adhesion, and soldering properties
of the copper alloys obtained in Example 4.
TABLE-US-00003 TABLE 3 Composition Cooling Inclusion Maximum
Conduc- Plating Co Si rate after volume inclusion Tensile tivity
adhesion Sample (mass (mass Co/ O.sub.2 H.sub.2 aging ratio size
strength (% 500 100 Soldering Kind number %) %) Si (ppm) (ppm)
(.degree. C./h) (%) (.mu.m) (N/mm.sup.2) IACS) hours hours property
Present 39 1.28 0.30 4.3 9 0.3 30 0.4 0.5 702 61 .largecircle.
.largecircle. .largecircle. inven- 40 1.30 0.31 4.2 20 0.3 30 0.4
0.5 701 60 .largecircle. .DELTA. .DELTA. tion 41 1.27 0.29 4.4 50 5
30 0.4 0.5 700 60 .DELTA. X .DELTA. product
[0085] Table 3 reveals that the copper alloys of Products 39 to 41
of the present invention each had a maximum inclusion size of 2
.mu.m or less, an inclusion volume ratio of 0.5 vol % or less, a
tensile strength of 700 N/mm.sup.2 or more, and a conductivity of
60% IACS or more. The copper alloy of Product 39 of the present
invention had excellent plating adhesion and soldering properties
after 500 hours and 1,000 hours. The results indicated that the
plating adhesion and soldering properties improve by adjusting the
O.sub.2 content to 10 ppm or less and the H.sub.2 content to 1 ppm
or less in the copper alloy.
[0086] As described above, the copper alloy of the present
invention has excellent strength and conductivity, that is, a
tensile strength of 700 N/mm.sup.2 or more, and a conductivity of
60% IACS or more. Further, the method of producing a copper alloy
of the present invention allows production of a copper alloy having
a tensile strength of 700 N/mm.sup.2 or more and a conductivity of
60% IACS or more.
* * * * *