U.S. patent application number 12/741309 was filed with the patent office on 2011-02-17 for copper alloy sheet material.
Invention is credited to Tatsuhiko Eguchi, Kiyoshige Hirose, Hiroshi Kaneko, Kuniteru Mihara.
Application Number | 20110038753 12/741309 |
Document ID | / |
Family ID | 40625761 |
Filed Date | 2011-02-17 |
United States Patent
Application |
20110038753 |
Kind Code |
A1 |
Kaneko; Hiroshi ; et
al. |
February 17, 2011 |
COPPER ALLOY SHEET MATERIAL
Abstract
A copper alloy sheet material which has a tensile strength of
730-820 MPa and contains at least nickel (Ni) and silicon (Si),
with the remainder being copper (Cu) and inevitable impurities.
When the sheet material has a shape capable of 180.degree. tight
bending and the width and thickness of this sheet material are
expressed by W (unit: mm) and T (unit: mm) respectively, then the
product of W and T is 0.16 or less. Preferably, the sheet material
is constituted of an alloy containing nickel at 1.8-3.3 mass %,
silicon at 0.4 mass %, and chromium (Cr) at 0.01-0.5 mass %, with
the remainder being copper and inevitable impurities. The sheet
material may further contain one or more of: at least one member
selected among tin (Sn), magnesium (Mg), silver (Ag), manganese
(Mn), titanium (Ti), iron (Fe), and phosphorus (P) in a total
amount of 0.01-1 mass %; zinc (Zn) at 0.01-10 mass %, cobalt (Co)
at and 0.01-1.5 mass %.
Inventors: |
Kaneko; Hiroshi; (Tokyo,
JP) ; Hirose; Kiyoshige; (Tokyo, JP) ; Mihara;
Kuniteru; (Tokyo, JP) ; Eguchi; Tatsuhiko;
(Tokyo, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
40625761 |
Appl. No.: |
12/741309 |
Filed: |
November 5, 2008 |
PCT Filed: |
November 5, 2008 |
PCT NO: |
PCT/JP2008/070139 |
371 Date: |
July 16, 2010 |
Current U.S.
Class: |
420/473 ;
420/485; 420/487; 420/488 |
Current CPC
Class: |
B21B 3/00 20130101; C22F
1/08 20130101; C22C 9/04 20130101; B21B 2003/005 20130101; C22C
9/06 20130101 |
Class at
Publication: |
420/473 ;
420/485; 420/487; 420/488 |
International
Class: |
C22C 9/06 20060101
C22C009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2007 |
JP |
2007-287066 |
Claims
1.-7. (canceled)
8. A copper alloy sheet material having a tensile strength of 730
to 820 MPa, and comprising at least Ni and Si in addition to copper
and inevitable impurities, wherein when the material is capable of
180.degree. tight bending and the sheet width is taken to be W
(unit: mm) and the sheet thickness is taken to be T (unit: mm), the
product of W and T (unit: mm.sup.2) is 0.16 or less.
9. The copper alloy sheet material of claim 8, wherein second-phase
particles existing on a grain boundary exist at a density of
10.sup.4 to 10.sup.8 particles/mm.sup.2, and the average grain size
is 10 .mu.m or less.
10. The copper alloy sheet material of claim 8, wherein the value
of ratio r/f of the particle size r (unit: .mu.m) of second-phase
particles inside the grain and on the grain boundary and the volume
fraction f of the particles is at least 1 and not more than 100,
and the average grain size is 10 .mu.m or less.
11. The copper alloy sheet material of claim 9, wherein of said
second-phase particles, the ratio of particles comprising Cr as a
constituent element is 50% or more.
12. The copper alloy sheet material of claim 10, wherein of said
second-phase particles, the ratio of particles comprising Cr as a
constituent element is 50% or more.
13. The copper alloy sheet material of claim 8, wherein the alloy
composition includes Ni at 1.8 to 3.3 mass %, Si at 0.4 to 1.1 mass
% and Cr at 0.01 to 0.5 mass %, with the remainder being Cu and
inevitable impurities.
14. The copper alloy sheet material of claim 9, wherein the alloy
composition includes Ni at 1.8 to 3.3 mass %, Si at 0.4 to 1.1 mass
% and Cr at 0.01 to 0.5 mass %, with the remainder being Cu and
inevitable impurities.
15. The copper alloy sheet material of claim 10, wherein the alloy
composition includes Ni at 1.8 to 3.3 mass %, Si at 0.4 to 1.1 mass
% and Cr at 0.01 to 0.5 mass %, with the remainder being Cu and
inevitable impurities.
16. The copper alloy sheet material of claim 11, wherein the alloy
composition includes Ni at 1.8 to 3.3 mass %, Si at 0.4 to 1.1 mass
% and Cr at 0.01 to 0.5 mass %, with the remainder being Cu and
inevitable impurities.
17. The copper alloy sheet material of claim 12, wherein the alloy
composition includes Ni at 1.8 to 3.3 mass %, Si at 0.4 to 1.1 mass
% and Cr at 0.01 to 0.5 mass %, with the remainder being Cu and
inevitable impurities.
18. The copper alloy sheet material of claim 13, comprising one
kind or two kinds or more elements from among at least one of Sn,
Mg, Ag, Mn, Ti, Fe and P at 0.01 to 1 mass %, Zn at 0.01 to 10 mass
% and Co at 0.01 to 1.5 mass %.
19. The copper alloy sheet material of claim 14, comprising one
kind or two kinds or more elements from among at least one of Sn,
Mg, Ag, Mn, Ti, Fe and P at 0.01 to 1 mass %, Zn at 0.01 to 10 mass
% and Co at 0.01 to 1.5 mass %.
20. The copper alloy sheet material of claim 15, comprising one
kind or two kinds or more elements from among at least one of Sn,
Mg, Ag, Mn, Ti, Fe and P at 0.01 to 1 mass %, Zn at 0.01 to 10 mass
% and Co at 0.01 to 1.5 mass %.
21. The copper alloy sheet material of claim 16, comprising one
kind or two kinds or more elements from among at least one of Sn,
Mg, Ag, Mn, Ti, Fe and P at 0.01 to 1 mass %, Zn at 0.01 to 10 mass
% and Co at 0.01 to 1.5 mass %.
22. The copper alloy sheet material of claim 17, comprising one
kind or two kinds or more elements from among at least one of Sn,
Mg, Ag, Mn, Ti, Fe and P at 0.01 to 1 mass %, Zn at 0.01 to 10 mass
% and Co at 0.01 to 1.5 mass %.
23. The copper alloy sheet material of claim 8, wherein when the
material is maintained at 165.degree. C. for 3000 hours, the stress
relaxation rate is 30% or less.
24. The copper alloy sheet material of claim 9 or 10, wherein when
the material is maintained at 165.degree. C. for 3000 hours, the
stress relaxation rate is 30% or less.
25. The copper alloy sheet material of claim 11 or 12, wherein when
the material is maintained at 165.degree. C. for 3000 hours, the
stress relaxation rate is 30% or less.
26. The copper alloy sheet material of any one of the claims 13 to
17, wherein when the material is maintained at 165.degree. C. for
3000 hours, the stress relaxation rate is 30% or less.
27. The copper alloy sheet material of any one of the claims 18 to
22, wherein when the material is maintained at 165.degree. C. for
3000 hours, the stress relaxation rate is 30% or less.
Description
TECHNICAL FIELD
[0001] The present invention relates to a copper alloy sheet
material.
BACKGROUND ART
[0002] Characteristics that are required for copper alloy sheet
material that is used for electrical/electronic equipment include
for example, constant electrical conductivity, constant tensile
strength, constant bending workability, and constant stress
relaxation resistance. In recent years, as electrical/electronic
equipment have become more compact, more lightweight, more highly
functional and more densely packaged, and as the operating
temperature has increased, the level of these required
characteristics has also increased.
[0003] Conventionally, in addition to iron-based materials,
copper-based materials such as phosphor bronze, red brass and brass
have typically been used as materials for electrical/electronic
equipment. Through a combination of solid solution strengthening
using Sn or Zn, and work hardening by cold working such as rolling
or drawing, the strength of these alloys has been improved.
However, alloys that are obtained through these strengthening
methods have insufficient electrical conductivity for the recent
required level, and since high strength is obtained by adding a
high cold working rate, the bending workability and stress
relaxation resistance are also insufficient.
[0004] As an alternative strengthening method, precipitation
strengthening causes microscopic secondary-phase particles on a
nanometer order to precipitate into a material. In addition to
increasing strength, this strengthening method has the merit of
simultaneously improving the electrical conductivity, so it is used
in many alloy systems. Of these, Cu--Ni--Si system alloys that are
strengthened by precipitating microscopic Ni and Si compounds into
Cu (for example, CDA70250, which is a registered alloy of the CDA
(Copper Development Association); refer to patent documents 1 and
2) are increasingly being used in the market.
[0005] Patent document 1: JP-A-1999-43731
[0006] Patent document 2: JP-T-2005-532477
DISCLOSURE OF THE INVENTION
[0007] Generally, in the case of precipitation-hardened alloys,
before aging precipitation heat treatment for obtaining a
microscopic precipitation state, solution heat treatment is
employed as an intermediate process for solidifying the solution of
solute atoms. The temperature of this process differs depending on
the alloy system and the solute concentration, however, is a high
temperature of about 750.degree. C. Since the temperature of this
solution heat treatment is a high temperature, there is a problem
in that the grain size of the material becomes coarse. When the
grain size is coarse, problems occur such as cracking due to the
promotion of localized deformation during bending, concentration of
electric current when bent sections are used as contacts due to
large creases on the surface of the bent sections, or cracking of
plating that is coated on the surface of the material. Moreover,
when the temperature of the solution heat treatment is lowered in
order to prevent the grain size from becoming coarse, problems
occur in that the amount of atoms that enter into solid solution
decreases, the density of microscopic precipitate in the aging
treatment decreases, the amount of age hardening decreases and the
material strength decreases.
[0008] Therefore in solution heat treatment at a temperature at
which solute Ni and Si atoms can sufficiently enter into solid
solution, there is a demand for technology by which the grain size
can be kept small and material having high strength and good
bending workability can be obtained.
[0009] Taking the aforementioned problems into consideration, it is
the object of the present invention to provide a copper alloy sheet
material for use in electrical/electronic equipment that has
excellent bending workability and strength.
[0010] The inventors performed research of copper alloys suitable
for use in electrical/electronic equipment, and by focusing their
attention on methods of dispersing second-phase particles in order
to greatly improve the bending workability and strength of
Cu--Ni--Si series copper alloys, developed the present invention
after much dedicated study. In addition, the inventors found the
best modes of the present invention by discovering added elements
that function to improve the strength and stress relaxation
resistance characteristics without impairing electrical
conductivity. The second-phase particles referred to here are
precipitates and crystallized matter.
[0011] The following means are provided with the present
invention:
[0012] (1) A copper alloy sheet material having a tensile strength
of 730 to 820 MPa, and comprising at least Ni and Si in addition to
copper and inevitable impurities, wherein when the material is
capable of 180.degree. tight bending and the sheet width is taken
to be W (unit: mm) and the sheet thickness is taken to be T (unit;
mm), the product of W and T (unit: mm.sup.2) is 0.16 or less.
[0013] (2) The copper alloy sheet material of item (1) wherein
second-phase particles existing on a grain boundary exist at a
density of 10.sup.4 to 10.sup.8 particles/mm.sup.2, and the average
grain size is 10 .mu.m or less.
[0014] (3) The copper alloy sheet material of item (1) wherein the
value of the ratio r/f of the particle size r (unit: .mu.m) of
second-phase particles inside the grain and on the grain boundary
and the volume fraction f of the particles is at least 1 and not
more than 100, and the average grain size is 10 .mu.m or less.
[0015] (4) The copper alloy sheet material of item (2) or item (3)
wherein of the second-phase particles, the ratio of particles
comprising Cr as a constituent element is 50% or more.
[0016] (5) The copper alloy sheet material of any one of the items
1 to 4 wherein the alloy composition includes Ni at 1.8 to 3.3 mass
%, Si at 0.4 to 1.1 mass % and Cr at 0.01 to 0.5 mass %, with the
remaining being Cu and inevitable impurities.
[0017] (6) The copper alloy sheet material of any one of the items
1 to 5 comprising one kind or two kinds or more elements from among
at least one of Sn, Mg, Ag, Mn, Ti, Fe and P at 0.01 to 1 mass %,
Zn at 0.01 to 10 mass % and Co at 0.01 to 1.5 mass %.
[0018] (7) The copper alloy sheet material of any one of the items
1 to 6 wherein when the material is maintained at 165.degree. C.
for 3000 hours, the stress relaxation rate is 30% or less.
[0019] The above and other features and advantages of the present
invention will become better understood from the following detailed
description with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a drawing explaining a method for testing stress
relaxation resistance, where (a) of FIG. 1 shows before heat
treatment and (b) of FIG. 1 shows after heat treatment.
[0021] FIG. 2 is a graph showing the results of whether or not
cracking occurs when the sheet width W (mm) and sheet thickness T
(mm) of a test specimen are varied in examples and comparative
examples.
BEST MODE FOR CARRYING OUT THE INVENTION
[0022] The preferred embodiment of the copper alloy sheet material
of the present invention is explained in detail.
[0023] The tensile strength of the copper alloy sheet material of
the present invention is 730 to 820 MPa. More preferably, it is 740
to 800 MPa. The bending workability is such that under rigid
conditions such as when the product of the material sheet width W
(mm) and the material sheet thickness T (mm) is 0.16 (mm.sup.2) or
less, 180.degree. tight bending is possible. It is preferred that
this product of width W and thickness T be 0.14 or less. The
minimum value of this product of width W and thickness T is not
especially limited, however is normally 0.01 or greater.
[0024] Moreover, an electrical conductivity of 30% IACS is
preferred, and it is also preferred for the stress relaxation
resistance that when the material is maintained for 3000 hours or
more at 165.degree. C., the stress relaxation rate be 30% or
less.
[0025] Suitable dispersion of second-phase particles is effective
against grain coarsening during solutionization that causes bending
workability to worsen. This is because it is considered that when
grain is grown, a gain in energy occurs at the interface between
the dispersed particles and grain boundary when the grain boundary
passes the second-phase particles and suppresses grain boundary
migration.
[0026] The obtained grain size is preferably 10 .mu.m or less, and
more preferably 8 .mu.m or less, and yet even more preferably 6
.mu.m or less. The minimum value of grain size is not particularly
limited, however, normally is 2 .mu.m or more. The grain size is
measured according to the Japanese Industrial Standard JIS H 0501
(cutting method).
[0027] Regulating the preferred dispersion state of the present
invention in order to fully demonstrate the effect of obtaining
this controlled grain size can be performed by the following two
methods.
[0028] First, the second-phase particles that exist on the grain
boundary should exist at a density of 10.sup.4 to 10.sup.8
particles/mm.sup.2. In this case, it is further preferred that the
density be 5.times.10.sup.5 to 5.times.10.sup.7
particles/mm.sup.2.
[0029] Second, the value of the ratio r/f of the particle size r
(unit: .mu.m) of all of the second-phase particles inside the grain
and on the grain boundary and the volume fraction f of the
particles should be 1 to 100. The particle size r of the
second-phase particles is the arithmetic mean value of the particle
size of all of the measured particles. The notation f=0.005 for the
volume fraction f indicates 0.5 vol %.
[0030] The inventors discovered that these kinds of second-phase
particles possessed the preferred function of improving the stress
relaxation resistance. The stress relaxation phenomenon is
considered to be caused by dislocations inside the grain moving to
the grain boundary, or by grain boundary slippage occurring in part
of the grain boundary, with the strain inside the elastic limit
changing to permanent strain. In the case of the aforementioned
preferred second-phase particles of the present invention, the
particles existing inside the grain function to suppress moving of
dislocations, and the particles existing at the grain boundary
suppress slipping movement of the grain boundary.
[0031] Of all these second-phase particles, it is further preferred
that the percentage of particles that include Cr as a constituent
element be 50% or greater. This is because when Cr is included, the
particles can exist as stable compounds without entering the solid
solution of Cu even at high temperature. This contributes to a
higher density of second-phase particles and increases the effect
of suppressing the growth of grain. It is even more preferable that
this percentage be 70% or greater. The maximum value of this
percentage is not particularly limited, however normally is 90% or
less.
[0032] By controlling the composition amounts of the main solute
components Ni and Si, favorable characteristics can be obtained as
follows. It is preferred that the contained amount of Ni be 1.8 to
3.3 mass %, and more preferably 2.0 to 3.0 mass %, and the
contained amount of Si be 0.4 to 1.1 mass %, and more preferably
0.5 to 1.0 mass %. Too large of an amount of these elements leads
to a drop in electrical conductivity, and causes cracking at the
grain boundary by the precipitation at the grain boundary during
bending. However, too small of an amount of these elements leads to
the insufficient strength.
[0033] Cr precipitates as the second-phase particle with Ni or Si,
and is effective in controlling the grain size. Furthermore, Cr per
se performs precipitation hardening. It is preferred that the
contained amount of Cr be 0.01 to 0.5 mass %, and more preferably
0.03 to 0.4 mass %. When the amount is too small, the effect is not
obtained, and when the amount is to large, adverse effects occur in
that the Cr crystallizes out as coarse crystallized matter during
solidification, which causes the plating characteristics to worsen,
and promotes starting points for cracking as well as the
propagation of cracking during plastic working.
[0034] In addition, at least one kind of element that is selected
from among (1) at least one of Sn, Mg, Ag, Mn, Ti, Fe and P for a
total of 0.01 to 1 mass %, (2) Zn at 0.01 to 10 mass %, and (3) Co
at 0.01 to 1.5 mass % can be added in order to improve the alloy
characteristics.
[0035] These elements improve the strength and the stress
relaxation resistance characteristic, and especially Sn and Mg are
very effective for that. Zn and Sn function to improve solder
joinability, Co functions to improve electrical conductivity, and
Mn functions to improve hot workability. When the contained amount
when added is too small, the effect is not sufficient, and too
large of an amount leads to a drop in electrical conductivity.
[0036] In the case of the stress relaxation resistance
characteristics, it is preferred that the stress relaxation rate be
30% or less when the material is kept at 165.degree. C. for 3000
hours, and more preferably 25% or less.
[0037] The preferred method for manufacturing the copper alloy
sheet material of the present invention is explained below. The
copper alloy sheet material of the present invention can, for
example, be manufactured by a method comprising the steps of
casting, (homogenization) heat treatment, hot working (for example,
hot rolling) and cold working (for example, cold rolling) (1),
solution heat treatment, cold working (for example, cold rolling)
(2), (aging precipitation) heat treatment, cold working (for
example cold rolling) (3) and (strain relief) annealing. Here, it
is preferred that rapid cooling and facing be performed after heat
treatment and before cold working (1).
[0038] First, the copper alloy material is prepared by combining
all of the elements so that the specified alloy constituent
composition is achieved, with the remaining part being Cu and
inevitable impurities, and this is melted using a high-frequency
melting furnace. Casting is performed at a preferable cooling rate
of 0.1 to 100.degree. C./sec (more preferably, 0.5 to 50.degree.
C./sec) to obtain an ingot. Heat treatment (homogenization) is
performed by preferably maintaining the ingot at 900 to
1050.degree. C. for 0.5 to 10 hours (more preferably, for 0.8 to 8
hours). Hot working (hot rolling) is preferably performed at a
reduction percentage (rolling reduction) of 50% or greater (more
preferably, 60 to 98%), and a processing temperature of 600.degree.
C. or greater (more preferably, 620 to 1000.degree. C.) to forma
sheet. Rapid cooling (for example, water cooling) is preferably
performed by cooling this sheet at a cooling rate of 10.degree.
C./sec or greater (more preferably, 15 to 300.degree. C./sec). This
hot rolled sheet can be faced according to a conventional method.
Cold working (cold rolling) (1) is preferably performed with a
reduction percentage of 90% or greater (more preferably, 92 to
99%). Solution heat treatment is preferably performed by
maintaining the material at 720 to 860.degree. C. for 3 sec to 2
hours (more preferably 5 sec to 0.5 hours). In the solution heat
treatment, it is preferred that treatment be performed within a
range of rising temperature from 400.degree. C. to 700.degree. C.
and a rate of temperature increase of 0.1.degree. C./sec to
200.degree. C./sec (more preferably, 0.5 to 100.degree. C./sec).
Cold working (cold rolling) (2) is preferably performed with a
reduction percentage of 5 to 50% (more preferably, 7 to 45%). Aging
precipitation heat treatment is preferably performed by maintaining
the material at 400.degree. C. to 540.degree. C. for 5 min to 10
hours (more preferably, at 410 to 520.degree. C. for 10 min to 8
hours). Cold working (cold rolling) (3) is preferably performed
with a reduction percentage of 10% or less (meaning greater than 0%
but not exceeding 10%). Strain relief annealing is preferably
performed by maintaining the material at 200.degree. C. to
600.degree. C. for 15 sec to 10 hours (more preferably, 250 to
570.degree. C. for 20 sec to 8 hours).
[0039] When there is sufficient strength after aging precipitation
heat treatment, cold working (3) and strain relief annealing do not
need to be performed after that and can be omitted.
[0040] By performing at least one process of the aforementioned
processes under the aforementioned preferable conditions, and
particularly by preferably performing all of the processes under
the preferable conditions, the specified preferred metallic
structure for the copper alloy sheet material of the present
invention can be obtained. For example, by adjusting the casting
speed (cooling speed during casting), it is possible to prevent
crystallization of Cr series compounds from occurring excessively.
In addition, by adjusting the temperature range and time during
which the material is maintained at that temperature during hot
rolling, it is possible to suppress coarse precipitation during hot
rolling, and suitable precipitation can be performed in a later
process. Moreover, the second-phase particles that suppress
coarsening of the grain mainly precipitate out during the
temperature rise of the solution heat treatment, however, in order
to effectively induce that precipitation, it is preferred that
processing be performed such that both the processing rate of the
cold working (1) process, which is the process prior to the
solution heat treatment process, and the rate of temperature rise
during the solution heat treatment be within the aforementioned
preferred conditions. Furthermore, by employing the cold working
(2) process before the aging precipitation heat treatment process,
it is possible to induce higher density of microscopic precipitate
that contributes to precipitation hardening, and suppress the
coarsening of second-phase particles that remain at the time of
solutionization during aging precipitation heat treatment.
[0041] The copper alloy sheet material of the present invention has
excellent strength and bending workability, and is suitable for use
in electrical/electronic equipment. The preferred copper alloy
sheet material of this present invention also has excellent
electrical conductivity and stress relaxation resistance. With the
characteristics described above, the copper alloy sheet of the
present invention can also be suitably used in lead frames,
connectors, and terminals of electrical/electronic equipment, and
is particularly suitable for use in connectors, terminals, relays,
switches and sockets that are used in automobiles.
[0042] There never before has been material having high strength
and high bending workability such as that of the present invention,
and this material will improve freedom when designing parts for
cutting-edge uses in the future, as well as have a large effect on
high functionality of electronic equipment. In addition, by having
increased strength makes it possible to make the copper alloy
material thinner, thus contributing to a reduction in the amount of
global resources used.
Examples
[0043] The present invention will be explained in further detail
below based on examples; however, the present invention is not
limited to these examples.
Examples 1
[0044] An alloy comprising elements that were combined so that
their composition was as shown in the table, with the remaining
part being Cu and inevitable impurities, was melted in a
high-frequency melting furnace, and then cast at a cooling rate of
0.1 to 100.degree. C./sec to obtain an ingot. After maintaining
this ingot at 900 to 1050.degree. C. for 0.5 to 10 hours, a sheet
was formed by hot working with the percentage of reduction being
50% or greater and the processing temperature being 600.degree. C.
or greater, then the sheet was water cooled at a cooling rate of
10.degree. C./sec or greater. The hot rolled sheet was then faced,
and cold working (1) was performed at a reduction percentage of 90%
or greater. Solution heat treatment was then performed by
maintaining the sheet at 720 to 860.degree. C. for 3 sec to 2
hours. Solution heat treatment was performed such that the rate of
temperature rise during a temperature rise at 400.degree. C. to
700.degree. C. was in the range of 0.1.degree. C./sec to
200.degree. C./sec. After that, cold working (2) was performed at a
reduction percentage of 5 to 50%, aging precipitation heat
treatment was performed by maintaining the material at 400.degree.
C. to 540.degree. C. for 5 min to 10 hours, cold working (3) was
performed at a reduction percentage of 10% or less, and strain
relief annealing was performed by maintaining the material at
200.degree. C. to 600.degree. C. for 15 sec to 10 hours to obtain
material to be used as test material. In the case where there was
sufficient strength after aging precipitation heat treatment, the
cold working (3) and strain relief annealing after that aging
precipitation heat treatment were not performed.
[0045] The comparative examples given below that are presented with
the examples were made outside the range of these manufacturing
conditions in order to be separated from the range of examples of
the present invention.
[0046] Details of the comparative examples are given below.
[0047] Comparative example 1-1 is an example in which the cooling
rate during the casting process was too low.
[0048] Comparative example 1-2 is an example in which the
temperature during the homogenization process was too low.
[0049] Comparative example 1-3 is an example in which the
temperature during the aging precipitation heat treatment process
was too high.
[0050] Comparative example 1-4 is an example in which the
temperature during the homogenization process was too low.
[0051] In each of the tables, for example, in the case of the test
results of invention example 1-1 as the ID number in Table 1, in
regards to the evaluation of the bending workability, judgment
results for bending work conditions outside the range of the
invention W.times.T>0.16 are also displayed on the same line as
the judgment results for the bending work conditions within the
range of the invention, however, this is done for convenience of
listing the ID number. This will be the same for all of the test
examples given in each of the tables below.
[0052] The characteristics presented below were investigated for
these test materials.
a. Electrical Conductivity [EC]
[0053] The electrical conductivity (% IACS) was calculated by using
the four-terminal method to measure the specific resistance of the
material in an isothermal bath that was maintained at 20.degree. C.
(.+-.0.5.degree. C.). The spacing between terminals was 100 mm.
b. Tensile Strength [TS]
[0054] Three test pieces that were cut out from the direction
parallel to the rolling direction according to JIS Z2201-13B were
measured according to JIS Z2241, and the average value (MPa) is
given.
c. 180.degree. Tight Bending Workability
[0055] Bending work was performed according to JIS 22248. After
preliminary bending was performed using a 0.4 mm R 90.degree.
bending die, tight bending was performed using a compression
testing machine. The bending location was observed by using a
50.times. optical microscope to visually inspect whether or not
there was cracking on the outside of the bent section. The sheet
width W and sheet thickness T conditions of the test piece are
indicated in mm. In the table "GW (Good way)" indicates testing in
the case where the bending axis is perpendicular to the rolling
direction, and "BW (Bad way)" indicates testing in the case where
the bending axis is parallel to the rolling direction. In the
table, the observation results are indicated as "O (Good)" when no
cracking occurred, and as "X (Bad)" when cracking occurred.
d. Particle Size [r], Distribution Density [.rho.] and Volume
Fraction [f] of the Second-Phase Particles
[0056] Observation test pieces were formed by punching the test
material into 3 mm diameter pieces, and polishing the pieces to a
thin film by using a twin-jet polishing method. Using a
transmission electron microscope having an accelerating voltage of
300 kV, 5000.times. photographs were taken arbitrarily every ten
fields of view, and the particle size r (.mu.m) and distribution
density .rho. (particles/mm.sup.2) were measured on the
photographs. The particle size r of the second-phase particles was
found by first, finding the particle size of each particle, then,
for all of the measured particles, finding the calculated average
value of the particle sizes of all of the particles. The particle
size of each particle was taken to be the calculated average value
of the long diameter and short diameter of the particle. Moreover,
the thickness of an observed test piece was measured from the
thickness contours, and of the total volume of an observed field of
view, the percentage of the volume occupied by the second-phase
particles was taken to be the volume fraction f.
e. Identification of Second-Phase Constituent Atoms [C]
[0057] An EDX spectrometer that was attached to the TEM was used.
Analysis was performed for 20 second-phase particles, and the
percentage of the total number measured comprising Cr was
calculated.
f. Stress Relaxation Resistance [SR]
[0058] The stress relaxation resistance was measured according to
the Japan Electronics and Information Technology Industries
Association standards EMAS-3003 under conditions of 165.degree. C.
for 3000 hours. An initial stress that was 80% the offset yield
strength (proof stress) was applied by the cantilever method.
[0059] FIG. 1 is a drawing explaining the method for testing the
stress relaxation, where (a) of FIG. 1 shows the state before heat
treatment, and (b) of FIG. 1 shows the state after heat treatment.
The stress relaxation rate (%) was calculated as
H.sub.t-H1)/.delta..sub.0.times.100.
g. Average Grain Size [GS]
[0060] The average grain size was measured according to JIS 1-10501
(cutting method). Measurement was performed for a cross-section
that is parallel to the rolling direction, and a cross-section that
is perpendicular to the rolling direction, and the average of both
was taken. Observation of the metallic structure was done by
chemically edging a mirror polished material surface and performing
SEM reflection electron imaging.
TABLE-US-00001 TABLE 1 Alloy % of composition Bending workability
particles Ni Si Cr .rho. (Cracking Y/N) (W unit: mm) com- mass mass
mass Particles/ T GW BW TS prising GS EC % SR ID Number % % %
mm.sup.2 mm W = 0.5 W = 1 W = 2 W = 0.5 W = 1 W = 2 MPa Cr % .mu.m
IACS % Invention 1.81 0.50 -- 6 .times. 10.sup.4 0.30 .largecircle.
X X .largecircle. X X 742 0 5.2 42.1 28.2 example 1-1 Invention
2.32 0.65 -- 9 .times. 10.sup.4 0.25 .largecircle. X X
.largecircle. X X 770 0 4.3 40.2 27.4 example 1-2 Invention 2.81
0.79 -- 7 .times. 10.sup.5 0.20 .largecircle. X X .largecircle. X X
784 0 6.8 39.5 28.1 example 1-3 Invention 3.28 0.94 -- 2 .times.
10.sup.6 0.15 .largecircle. .largecircle. X .largecircle.
.largecircle. X 792 0 7.0 38.6 26.7 example 1-4 Invention 1.83 0.50
0.21 2 .times. 10.sup.5 0.08 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 755 85 4.8
43.2 28.6 example 1-5 Invention 2.36 0.65 0.15 3 .times. 10.sup.6
0.15 .largecircle. .largecircle. X .largecircle. .largecircle. X
769 75 5.5 39.5 28.3 example 1-6 Invention 2.84 0.79 0.11 2 .times.
10.sup.7 0.12 .largecircle. .largecircle. X .largecircle.
.largecircle. X 785 95 4.2 38.2 27.5 example 1-7 Invention 3.24
0.94 0.25 8 .times. 10.sup.7 0.08 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 805 90 6.2
36.1 26.8 example 1-8 Comparative 2.34 0.66 -- 3 .times. 10.sup.3
0.25 X X X X X X 725 0 13.5 39.2 28.2 example 1-1 Comparative 2.82
0.77 -- 7 .times. 10.sup.3 0.20 X X X X X X 762 0 18.2 38.2 29.3
example 1-2 Comparative 2.35 0.62 0.15 2 .times. 10.sup.9 0.30 X X
X X X X 719 65 12.9 39.5 28.0 example 1-3 Comparative 2.81 0.75
0.21 5 .times. 10.sup.3 0.15 X X X X X X 758 45 17.5 37.5 27.9
example 1-4
[0061] As can be clearly seen from Table 1, invention examples 1-1
to 1-8 have excellent strength, electrical conductivity, bending
workability and stress relaxation resistance characteristics.
However, when some of the elements of the present invention are not
satisfied, some characteristics may become inferior. For example,
comparative examples 1-1 to 1-4 are all examples in which the
bending workability is inferior. In comparative examples 1-1, 1-2
and 1-4, the density of precipitate on the grain boundary is low,
and the grain size becomes coarse. Moreover, in comparative example
1-3, the density of precipitate on the grain boundary is high, and
it was observed that cracking occurred at the grain boundary.
Examples 2
[0062] The same investigation as was performed for examples 1 was
performed for a copper alloy comprising the composition shown in
Table 2 with the remaining part being Cu and inevitable impurities.
The manufacturing method and measurement method were the same as
for examples 1.
[0063] The comparative examples given below that are presented with
the examples were made outside the range of these manufacturing
conditions in order to be separated from the range of examples of
the present invention. Details of the comparative examples are
given below.
[0064] Comparative example 2-1 is an example in which the
processing rate during cold working (cold rolling) was too low.
[0065] Comparative example 2-2 is an example in which the
temperature during the homogenization process was too low.
[0066] Comparative example 2-3 is an example in which the cooling
rate during the casting process was too low.
[0067] Comparative example 2-4 is an example in which the
temperature during the homogenization process was too low.
TABLE-US-00002 TABLE 2 Alloy % of composition Bending workability
particles Ni Si Cr (Cracking Y/N) (W unit: mm) com- mass mass mass
T GW BW TS prising GS EC % SR ID Number % % % r/f mm W = 0.5 W = 1
W = 2 W = 0.5 W = 1 W = 2 MPa Cr % .mu.m IACS % Invention 1.91 0.55
-- 45.1 0.30 .largecircle. X X .largecircle. X X 743 0 7.1 41.8
27.1 example 2-1 Invention 2.41 0.68 -- 15.4 0.25 .largecircle. X X
.largecircle. X X 772 0 5.8 40.6 26.7 example 2-2 Invention 2.72
0.75 -- 17.2 0.20 .largecircle. X X .largecircle. X X 789 0 6.2
39.8 28.2 example 2-3 Invention 3.11 0.89 -- 10.4 0.15
.largecircle. .largecircle. X .largecircle. .largecircle. X 790 0
4.7 38.2 27.6 example 2-4 Invention 1.93 0.55 0.21 25.2 0.25
.largecircle. X X .largecircle. X X 751 90 5.6 43.1 26.3 example
2-5 Invention 2.45 0.68 0.15 12.1 0.15 .largecircle. .largecircle.
X .largecircle. .largecircle. X 773 80 6.3 39.6 28.5 example 2-6
Invention 2.76 0.75 0.11 5.4 0.10 .largecircle. .largecircle. X
.largecircle. .largecircle. X 783 85 4.5 38.3 27.4 example 2-7
Invention 3.18 0.89 0..25 72.3 0.08 .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. 802 75 7.4
36.6 26.8 example 2-8 Comparative 2.44 0.66 -- 24.5 0.15
.largecircle. X X .largecircle. X X 680 0 5.2 42.1 29.5 example 2-1
Comparative 2.74 0.76 -- 145.7 0.30 X X X X X X 771 0 19.3 39.5
30.2 example 2-2 Comparative 2.41 0.65 0.15 0.71 0.12 X X X X X X
765 45 18.2 39.1 29.2 example 2-3 Comparative 2.72 0.73 0.15 120.2
0.25 X X X X X X 761 75 16.2 37.5 27.8 example 2-4
[0068] As can be clearly seen from Table 2, invention examples 2-1
to 2-8 have excellent strength, electrical conductivity, bending
workability and stress relaxation resistance characteristics.
However, when some of the elements of the present invention are not
satisfied, some characteristics may become inferior. For example,
comparative example 2-1 is an example in which the tensile strength
became inferior. In this comparative example 2-1, the
solutionization temperature was lowered and grain size was made
small, however, precipitation hardening was thought to be
insufficient and there was not enough strength. Comparative
examples 2-2 and 2-4 are examples in which the bending workability
became inferior. In these comparative examples 2-2 and 2-4, it was
found that the precipitation fraction was small, so the r/f value
became large and the grain size became coarse. Comparative example
2-3 is an example in which bending workability was inferior. In
this comparative example 2-3, it was found that the size of the
second-phase particles was small, so the r/f value became small,
and because the grain could not be effectively controlled, the
grain size became coarse.
Examples 3
[0069] The same investigation as was performed for examples 1 was
performed for a copper alloy comprising the composition shown in
Table 3 with the remaining part being Cu and inevitable impurities.
The manufacturing method and measurement method were the same as
for examples 1.
[0070] The comparative examples below that are presented with the
examples in Table 3 were made with the contained amounts of Ni and
Si outside the preferred range of the present invention.
TABLE-US-00003 TABLE 3 Bending workability (Cracking Y/N) Alloy
composition Other added (W unit: mm) Ni Si Cr elements .rho. T GW
ID Number mass % mass % mass % mass % Particles/mm.sup.2 mm W = 0.5
W = 1 W = 2 Invention example 3-1 1.81 0.51 0.15 0.1Mn, 0.05P 6
.times. 10.sup.4 0.20 .largecircle. X X Invention example 3-2 2.31
0.65 0.18 0.1Mg, 0.15Sn, 0.5Zn 9 .times. 10.sup.4 0.25
.largecircle. X X Invention example 3-3 2.81 0.77 0.21 0.3Ag, 0.1Ti
8 .times. 10.sup.5 0.15 .largecircle. .largecircle. X Invention
example 3-4 3.26 0.92 0.19 0.2Co, 0.1Fe 7 .times. 10.sup.5 0.10
.largecircle. .largecircle. X Comparative example 3-1 1.61 0.31
0.15 0.2Sn, 0.15Mg 6 .times. 10.sup.5 0.20 .largecircle. X X
Comparative example 3-2 3.51 1.21 0.12 0.3Mn 2 .times. 10.sup.6
0.15 .largecircle. X X Bending workability (Cracking Y/N) (W unit:
mm) % of particles BW TS comprising Cr GS EC SR ID Number W = 0.5 W
= 1 W = 2 MPa % .mu.m % IACS % Invention example 3-1 .largecircle.
X X 748 85 5.2 38.2 26.2 Invention example 3-2 .largecircle. X X
765 75 4.8 39.1 23.6 Invention example 3-3 .largecircle.
.largecircle. X 772 80 6.2 37.2 27.3 Invention example 3-4
.largecircle. .largecircle. X 790 90 7.1 37.2 26.1 Comparative
example 3-1 .largecircle. X X 710 85 8.2 41.2 31.2 Comparative
example 3-2 .largecircle. X X 795 85 8.9 32.5 26.0
[0071] As can be clearly seen from Table 3, invention examples 3-1
to 3-4, in which the contained amounts of Ni and Si are especially
within the preferred range, have excellent strength, electrical
conductivity, bending workability, and stress relaxation resistance
characteristics. However, when the added amounts of Ni and Si are
not especially within the preferred range, some characteristics may
become inferior. For example, comparative example 3-1 is an example
in which the amounts of Ni and Si were inadequate, so there was
insufficient strength. Comparative example 3-2 is an example in
which the amounts of Ni and Si were large, so precipitation
occurred at the grain boundary, causing the bending workability to
become somewhat inferior. Of course it is not necessary for the
contained amounts of Ni and Si to be especially within the
preferred range, however, when outside this range, examples are
seen in which characteristics become inferior, so it is preferred
that when possible, the amount of Ni be within the range 1.8 to 3.3
mass %, and that the amount of Si be within the range 0.4 to 1.1
mass %.
Examples 4
[0072] The same investigation as was performed for examples 1 was
performed for a copper alloy comprising the composition shown in
Table 4 with the remaining part being Cu and inevitable impurities.
The manufacturing method and measurement method were the same as
for examples 1.
[0073] The comparative examples below that are presented with the
examples in Table 4 were made with the contained amounts of other
added elements outside the preferred range of the present
invention.
TABLE-US-00004 TABLE 4 Bending workability (Cracking Y/N) Alloy
composition Other added (W unit: mm) Ni Si Cr elements T GW ID
Number mass % mass % mass % mass % r/f mm W = 0.5 W = 1 W = 2
Invention example 4-1 1.91 0.57 0.15 0.2Co, 0.2Mn 23.2 0.20
.largecircle. X X Invention example 4-2 2.42 0.60 0.22 0.2Fe, 0.03P
44.2 0.15 .largecircle. .largecircle. X Invention example 4-3 2.74
0.71 0.1 0.2Ag, 0.3Ti 35.2 0.12 .largecircle. .largecircle. X
Invention example 4-4 3.18 0.60 0.2 0.4Sn, 1.0Zn, 0.1Mg 7.8 0.08
.largecircle. .largecircle. .largecircle. Comparative example 4-1
2.46 0.62 0.15 1.2Sn, 1.2Mg 125.4 0.15 .largecircle. X X
Comparative example 4-2 2.77 0.70 0.17 1.5Fe 144.2 0.12
.largecircle. .largecircle. .largecircle. Bending workability
(Cracking Y/N) (W unit: mm) % of particles BW TS comprising Cr GS
EC SR ID Number W = 0.5 W = 1 W = 2 MPa % .mu.m % IACS % Invention
example 4-1 .largecircle. X X 751 70 6.8 38.3 27.2 Invention
example 4-2 .largecircle. X X 765 75 7.8 39.6 27.8 Invention
example 4-3 .largecircle. .largecircle. X 780 80 7.2 37.6 25.6
Invention example 4-4 .largecircle. .largecircle. .largecircle. 802
85 5.1 38.0 24.2 Comparative example 4-1 X X X 785 40 12.2 28.0
33.2 Comparative example 4-2 .largecircle. .largecircle.
.largecircle. 669 35 13.1 25.2 40.2
[0074] As is clearly shown in Table 4, invention examples 4-1 to
4-4, in which the contained amounts of other added elements
(secondary added elements) other than Ni and Si were especially
within the preferred range, have excellent electrical conductivity,
bending workability and stress relaxation resistance
characteristics. However, when the contained amounts of those other
added elements are not especially within the preferred range, some
of the characteristics may become inferior. For example,
comparative example 4-1 is an example in which the bending
workability became inferior. In this comparative example 4-1, it is
thought that because the contained amount of the secondary added
elements was too large, the grain boundary became fragile.
Comparative example 4-2 is an example in which the mechanical
strength became inferior. In this comparative example 4-2, it is
thought that because the contained amount of the secondary added
elements was too large, compounds other than Ni--Si series
compounds that contribute to precipitation hardening were formed.
Of course, it is not necessary that the contained amounts of
secondary added elements be especially within the preferred range,
however, by being outside of this range, examples were seen in
which characteristics become inferior, so when adding other added
elements, it is preferred when possible that one or two or more
kinds of elements be included from among at least one of Sn, Mg,
Ag, Mn, Ti, Fe and P at a total of 0.01 to 1 mass %, Zn at 0.01 to
10 mass %, and Co at 0.01 to 1.5 mass %.
[0075] The results of examples 1 to 4 above are shown in FIG. 2. It
can be seen that with the examples of the invention, under the
conditions of 180.degree. tight bending and material dimensions
where the product of the test piece thickness T and the test piece
width W is 0.16 or less, processing was possible with no cracking;
however, for the comparative examples, processing was not
possible.
INDUSTRIAL APPLICABILITY
[0076] The copper alloy sheet material of the present invention can
be suitably applied for use in lead frames, connectors and terminal
materials for electrical/electronic equipment, for example,
connectors, terminal materials, relays, switches and sockets for
use in automobiles.
[0077] The present invention and examples thereof were explained,
however, unless specifically indicated, the invention is not
limited by any of the details of the explanation and should be
widely interpreted within the spirit and scope of the invention as
given in the accompanying claims.
[0078] This application claims priority from a Japanese patent
application serial No. 2007-287066 filed on Nov. 5, 2007, the
entire content of which is incorporated herein by reference.
* * * * *