U.S. patent application number 11/169760 was filed with the patent office on 2006-01-26 for copper-based alloy and method of manufacturing same.
Invention is credited to Kouichi Hatakeyama.
Application Number | 20060016528 11/169760 |
Document ID | / |
Family ID | 35134477 |
Filed Date | 2006-01-26 |
United States Patent
Application |
20060016528 |
Kind Code |
A1 |
Hatakeyama; Kouichi |
January 26, 2006 |
Copper-based alloy and method of manufacturing same
Abstract
This invention is a copper-based alloy for use in connectors,
lead frames, switches and relays and the like that has a superior
balance of conductivity, tensile strength and workability in
bending and method of manufacturing same. The alloy is manufactured
by taking an ingot of a copper-based alloy containing Ni, Sn, P and
also at least one or more elements selected from a group consisting
of Zn, Si, Fe, Co, Mg, Ti, Cr, Zr and Al in a total amount of
0.01-30 wt. % with the remainder being Cu and unavoidable
impurities, performing a combination process of cold rolling
followed by annealing at least one time and then performing cold
rolling at a percent reduction Z that satisfies the following
Formula (1): Z<100-10X-Y (1) [where Z is the percent cold
reduction (%), X is the Sn content (wt. %) among the various
elements, and Y is the total content (wt. %) of all elements other
than Sn and Cu] followed by low-temperature annealing performed at
a temperature below the recrystallization temperature. This causes
dispersion and precipitation of Ni--P compounds so that a
precipitation-strengthened type copper-based alloy with an x-ray
diffraction intensity ratio of the surface S.sub.ND as given by the
following formula is 0.05.ltoreq.S.sub.ND.ltoreq.0.15 [provided
that S.sub.ND=I{200}/[I{111}+I{220}+I{311}], where I{200} is the
x-ray diffraction intensity of the {100} plane, {111} is the x-ray
diffraction intensity of the {111} plane, I{220} is the x-ray
diffraction intensity of the {110} plane, and {311} is the x-ray
diffraction intensity of the {311} plane] and a superior balance of
conductivity, tensile strength, 0.2% yield strength, springiness,
Vickers hardness and bending workability is obtained.
Inventors: |
Hatakeyama; Kouichi;
(Iwata-shi, JP) |
Correspondence
Address: |
CLARK & BRODY
1090 VERMONT AVENUE, NW
SUITE 250
WASHINGTON
DC
20005
US
|
Family ID: |
35134477 |
Appl. No.: |
11/169760 |
Filed: |
June 30, 2005 |
Current U.S.
Class: |
148/684 ;
148/433; 420/472 |
Current CPC
Class: |
C22C 9/02 20130101; C22C
9/04 20130101; C22F 1/08 20130101; C22C 9/06 20130101 |
Class at
Publication: |
148/684 ;
148/433; 420/472 |
International
Class: |
C22F 1/08 20060101
C22F001/08; C22C 9/02 20060101 C22C009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 1, 2004 |
JP |
JP2004-195984 |
Claims
1. A copper-based alloy containing Ni, Sn, P and also at least one
or more elements selected from a group consisting of Zn, Si, Fe,
Co, Mg, Ti, Cr, Zr and Al in a total amount of 0.01-30 wt. % with
the remainder being Cu and unavoidable impurities, where the x-ray
diffraction intensity ratio of the surface S.sub.ND is such that
0.05.ltoreq.S.sub.ND.ltoreq.0.15 [provided that
S.sub.ND=l{200}/[l{111}+l{220}+l{311}], where l{200} is the x-ray
diffraction intensity of the {100} plane, l{111} is the x-ray
diffraction intensity of the {111} plane, l{220} is the x-ray
diffraction intensity of the {110} plane, and l{311} is the x-ray
diffraction intensity of the {311} plane].
2. A copper-based alloy containing Ni: 0.01-4.0 wt. %, Sn: 0.01-10
wt. % and P: 0.01-0.20 wt. % with the remainder being Cu and
unavoidable impurities, where the x-ray diffraction intensity ratio
of the surface S.sub.ND is such that
0.05.ltoreq.S.sub.ND.ltoreq.0.15 [provided that
S.sub.ND=l{200}/[l{111}+l{220}+l{311}], where l{200} is the x-ray
diffraction intensity of the {100} plane, l{111} is the x-ray
diffraction intensity of the {111} plane, l{220} is the x-ray
diffraction intensity of the {110} plane, and l{311} is the x-ray
diffraction intensity of the {311} plane].
3. A copper-based alloy containing Ni: 0.01-4.0 wt. %, Sn: 0.01-10
wt. % and P: 0.01-0.20 wt. % and also at least one or more elements
selected from a group consisting of Zn, Si, Fe, Co, Mg, Ti, Cr, Zr
and Al in a total amount of 0.01-30 wt. % with the remainder being
Cu and unavoidable impurities, where the x-ray diffraction
intensity ratio of the surface S.sub.ND is such that
0.05.ltoreq.S.sub.ND.ltoreq.0.15 [provided that
S.sub.ND=l{200}-[l{111}+l{220}+l{311}], where l{200} is the x-ray
diffraction intensity of the {100} plane, l{111} is the x-ray
diffraction intensity of the {111} plane, l{220} is the x-ray
diffraction intensity of the {110} plane, and l{311} is the x-ray
diffraction intensity of the {311} plane].
4. A method of manufacturing a copper-based alloy according to
claim 1, comprising the steps of: taking an ingot of a copper-based
alloy having the indicated elemental composition, performing a
combination process of cold rolling followed by annealing at least
one time and then performing intermediate rolling which is a
rolling process prior to a final cold rolling process, thereby
making the x-ray diffraction intensity ratio of the sheet surface
S.sub.ND such that 0.05.ltoreq.S.sub.ND.ltoreq.0.15, and thereafter
performing annealing to obtain sheet with a grain size of 20 .mu.m
or less, and then performing the final cold rolling and
low-temperature annealing at a temperature below the
recrystallization temperature.
5. A method of manufacturing a copper-based alloy according to
claim 1, comprising the steps of: taking an ingot of a copper-based
alloy having the indicated elemental composition, performing a
combination process of cold rolling followed by annealing at least
one time and then performing cold rolling at a percent reduction Z
that satisfies the following Formula (1): Z<100-10X-Y (1) [where
Z is the percent cold reduction (%), X is the Sn content (wt. %)
among the various elements, and Y is the total content (wt. %) of
all elements other than Sn and Cu] followed by low-temperature
annealing performed at a temperature below the recrystallization
temperature.
6. A method of manufacturing a copper-based alloy according to
claim 1, comprising the steps of: taking an ingot of a copper-based
alloy having the indicated elemental composition, performing a
combination process of cold rolling followed by annealing at least
one time and then performing cold rolling at a percent reduction Z
that satisfies the following Formula (1):
0.8(100-10X-Y)<Z<100-10X-Y (2) [where Z is the percent cold
reduction (%), X is the Sn content (wt. %) among the various
elements, and Y is the total content (wt. %) of all elements other
than Sn and Cu] followed by low-temperature annealing performed at
a temperature below the recrystallization temperature.
7. A method according to claim 4 wherein, prior to performing the
combination process, at least one process selected in advance from
among homogenization annealing and hot rolling is performed on the
ingot.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a copper-based alloy that has a
superior balance of conductivity, tensile strength and bending
workability and to a method of manufacturing same, and more
specifically to a copper-based alloy for use in consumer products,
for example, for forming blanks for narrow-pitch connectors for use
in telecommunications, blanks for automotive harness connectors,
blanks for semiconductor lead frames and blanks for compact
switches and relays and the like and a method of manufacturing
same.
[0003] 2. Background Art
[0004] Against the background of recent developments in portable
and mobile electronic equipment, where the pin thickness and pin
width of connectors mounted in computers, mobile phones, digital
video cameras and the like are typically 0.10-0.30 mm, there is a
trend for these to become even thinner and narrower as the final
product is made more compact. As a result of higher volumes of
information being input/output through each of these pins at higher
data rates, the Joule heat arising from the ON current causes the
temperature of the contacts to increase, sometimes even exceeding
the temperature tolerance of the insulation enclosing the contacts.
Moreover, some of the pins are used for supplying power, so the
material used for them must have a reduced conductor resistance,
namely a high conductivity, and thus the development of copper
alloys to replace low-conductivity brass and phosphor bronze has
become an urgent task. In addition, both strength/springiness and
flexibility are indispensable at the time of the press-molding of
pins, but making the molding size narrower and thinner becomes more
necessary from a different standpoint than that up until now.
[0005] On the other hand, in automotive electronics, in order to
handle increases in the number of circuits and mounting densities
accompanying increasingly electronic control systems, the
connectors mounted in automotive electronics must be made lighter
and space-saving by making the connectors more compact, so for
example, the width of a box-shaped female connector has been
reduced from 2.3 mm, which was the mainstream ten years ago, to
0.64 mm at present. Naturally, high conductivity is required in the
same manner as for portable electronics. In addition, in order to
maintain good connection properties after being molded into a
box-shaped connector, even though the sheet thickness is roughly
0.25 mm or nearly unchanged from in the past, strict shape
tolerances are required, forcing the use of states where the inside
radius R is nearly 0 or states of bending nearly to tight contact,
and thus the working conditions are more strict than in the
past.
[0006] Accordingly, if one wishes to improve conductivity even
while achieving both good strength/springiness and bending
workability, this cannot be achieved with brass or phosphor bronze
or other materials that are solid-solution strengthened by the
addition of large amounts of additive elements. Precipitation
strengthening of materials is one example of a method of increasing
the conductivity while also obtaining high strength and high
springiness, but if precipitation strengthening is used,
deterioration of the ductility and bending workability of the
material is ordinarily not negligible, and when it is attempted to
avoid this, the control of the amount of elements added and the
working and heat treatment processes required to control the size
and distribution of precipitates becomes complex and as a result
the manufacturing costs become higher (as in patent document
JP2000-80428A, for example). As one method still remaining for
solid-solution strengthened materials, measures can be taken to
suppress the amount of solid-soluble elements added that lead to
decreased conductivity, and to modify the machining and
heat-treatment processes, but reducing the solid-solution
strengthening elements leads to reduced strength so one must rely
on that much more on work hardening, so decreased ductility and
formability are unavoidable. At any rate, there has been a need to
establish methods of evaluation from unconventional standpoints and
adopt measures that extend the field of view to standpoints based
on studies of texture, but no dramatic improvements have been
achieved.
[0007] As a result of extensive studies performed in order to solve
the problems of the background art described above, the material
used for narrow-pitch connectors and automotive box connectors,
which are blanked to the desired shape by means of high-speed
press-molding using dies, is forced to assume the state where the
inside radius R of the box portion is nearly 0 or the state of
bending nearly to tight contact as the terminals tend to become
thinner and narrower, or more specifically the spring portion
becomes 0.10-0.25 mm thick and 0.10-0.30 mm wide, and so how to
achieve superior bending workability while maintaining high
strength came up as an important problem to be solved from the
standpoint of properties. Regarding bending workability in
particular, the state of stress on the convex surface of a bend at
the time of bending varies depending on the width/thickness ratio
W/t (the ratio of the test piece width W to the sheet thickness t)
from tension in a single axis to surface-strain tension, so it is
mandatory to improve the bending workability in consideration of
the surface-strain tension accompanying the deterioration of
bending workability.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is therefore to control
the crystal orientation of the material and thus provide a
copper-based alloy that has a superior balance of conductivity,
tensile strength and bending workability. and a method of
manufacturing same.
[0009] The present invention provides a copper-based alloy with
improved bending workability and a method of manufacturing same by
taking copper-based alloys and performing x-ray diffraction
focusing primarily on the ND plane (the surface of sheet material;
referred to in the present invention as the ND plane), and
controlling the strength in specific directions among the crystal
orientations thus obtained. Note that the x-ray diffraction
intensity referred to here indicates the integrated intensity in a
crystal orientation of the material as measured by the x-ray
diffraction method, for example.
[0010] Namely, the present invention provides: [0011] in its first
aspect, a copper-based alloy containing Ni, Sn, P and also at least
one or more elements selected from a group consisting of Zn, Si,
Fe, Co, Mg, Ti, Cr, Zr and Al in a total amount of 0.01-30 wt. %
(percent by weight; same hereinafter) with the remainder being Cu
and unavoidable impurities, where the x-ray diffraction intensity
ratio of the surface S.sub.ND is such that
0.05.ltoreq.S.sub.ND.ltoreq.0.15 [provided that
S.sub.ND=I{200}/[I{111}+I{220}+I{311}], where I{200} is the x-ray
diffraction intensity of the {100} plane, I{111} is the x-ray
diffraction intensity of the {111} plane, I{220} is the x-ray
diffraction intensity of the {110} plane, and I{311} is the x-ray
diffraction intensity of the {311} plane; the same applies
hereinafter]; [0012] in its second aspect, a copper-based alloy
containing Ni: 0.01-4.0 wt. %, Sn: 0.01-10 wt. % and P: 0.01-0.20
wt. % with the remainder being Cu and unavoidable impurities, where
the x-ray diffraction intensity ratio of the surface S.sub.ND is
such that 0.05.ltoreq.S.sub.ND.ltoreq.0.15; [0013] in its third
aspect, a copper-based alloy containing Ni: 0.01-4.0 wt. %, Sn:
0.01-10 wt. % and P: 0.01-0.20 wt. % and also at least one or more
elements selected from a group consisting of Zn, Si, Fe, Co, Mg,
Ti, Cr, Zr and Al in a total amount of 0.01-30 wt. % with the
remainder being Cu and unavoidable impurities, where the x-ray
diffraction intensity ratio of the surface S.sub.ND is such that
0.05.ltoreq.S.sub.ND.ltoreq.0.15; [0014] in its fourth aspect, a
method of manufacturing a copper-based alloy according to any of
the first through third aspects, comprising the steps of: taking an
ingot of a copper-based alloy having the indicated elemental
composition, performing a combination process of cold rolling
followed by annealing at least one time and then performing
intermediate rolling which is a rolling process prior to a final
cold rolling process, thereby making the x-ray diffraction
intensity ratio of the sheet surface S.sub.ND such that
0.05.ltoreq.S.sub.ND.ltoreq.0.15, and thereafter performing
annealing to obtain sheet with a grain size of 20 .mu.m or less,
and then performing the final cold rolling and low-temperature
annealing at a temperature below the recrystallization temperature;
[0015] in its fifth aspect, a method of manufacturing a
copper-based alloy according to any of the first through third
aspects, comprising the steps of: taking an ingot of a copper-based
alloy having the indicated elemental composition, performing a
combination process of cold rolling followed by annealing at least
one time and then performing cold rolling at a percent reduction Z
that satisfies the following Formula (1): Z<100-10X-Y (1) [where
Z is the percent cold reduction (%), X is the Sn content (wt. %)
among the various elements, and Y is the total content (wt. %) of
all elements other than Sn and Cu; the same applies hereinafter]
followed by low-temperature annealing performed at a temperature
below the recrystallization temperature [here, Formula (1) is
preferably replaced by the following Formula (2):
0.8(100-10X-Y)<Z<100-10X-Y (2)]; and [0016] in its sixth
aspect, a method according to the fourth or fifth aspect wherein,
prior to performing the combination process, at least one process
selected in advance from among homogenization annealing and hot
rolling is performed on the ingot.
[0017] The present invention provides a copper-based alloy that has
a superior balance of conductivity, tensile strength, 0.2% yield
strength, springiness, hardness and bendability and is suitable for
use in connectors, switches, relays and the like, and thus
satisfies the demand for material that can be made into thinner
sheet and finer wire in response to recent high-density mounting in
consumer electronics, telecommunications equipment and automotive
components. Particularly, the present invention is able to improve
remarkably the bending workability of high strength/high
springiness copper based alloy.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] The present invention will now be described in detail.
[0019] The present invention achieves improved bending workability
of copper-based alloys by, with particular attention to the
material surface, performing x-ray diffraction and controlling the
strength in specific directions among the orientations thus
obtained.
[0020] First, at the time of bending, one observes surface
roughness in the surface of the bend in the material, in the form
of wrinkles appearing parallel to the axis of bending, where the
convex portions of the wrinkles maintain a smooth state that is
near that of the initial surface, while the concave portions expose
a new surface. While it is preferable for articles molded by
bending to have no wrinkles, thin sheets of copper alloy used for
the connectors and such described above are required to have
superior bending workability and from the standpoint of
reliability, it is essential not only that no cracks occur in bends
but also that the surface roughness patterns are finely dispersed.
Not only do large wrinkle-shaped areas of surface roughness
patterns appear to be cracks but also they could easily become the
starting points for cracks when the connectors are attached or
detached and when subjected to impact in use
[0021] To increase the bending workability, the material must have
good uniform elongation, namely a large n value, but thin sheets of
tempered copper alloy for use in connectors are required to have
high strength and high springiness at the time of terminal
formation and mounting, and as a result the uniform elongation is
small or roughly 1/10 of that of fully annealed material, so this
effect cannot be expected. Accordingly, the only method left in
order to improve bending workability is to disperse the
wrinkle-shaped surface roughness patterns as finely as possible.
When the surface is observed upon varying the amount of bending
deformation, as the precursor stage to wrinkles, large numbers of
fine indentations and step-like patterns occur at intervals
generally on the order of the grain size. In other words, the grain
boundaries take the role of material defects that become
opportunities for constriction or necking. With increased amounts
of deformation, portions of them become linked in the direction of
the bending axis while elongating into wrinkles that are roughly
parallel to the bending axis. When the period and amplitude of
these wrinkles are observed, the width of the convex portions of
the wrinkles is equivalent to a plurality of grains, so how readily
they grow is thought to depend on the large number of microscopic
indentations and steps that is present.
[0022] Cu-based polycrystalline materials with the FCC
(face-centered cubic) structure have a combination of slip planes
{111} and slip directions <110> (where { } indicates all
equivalent planes, and < > indicates all equivalent
directions (orientations)), or namely they have twelve
{111}<110> slip systems, with one or more slip systems
becoming active at the time of deformation.
[0023] Now, taking the surface of the sheet material to be the ND
plane, attention is focused on four main types of planes, namely
the {110} planes, {111} planes, {311} planes and the {100} planes.
At the time of bending deformation, eight slip systems out of the
twelve slip systems can be active, and the {100} plane that has the
best symmetry of slip systems has the greatest effect on bending
deformation. The {110} plane, {111} plane, {311} plane and other
orientations tend to be where strain occurs more readily in the
width direction than the thickness direction, so in polycrystalline
materials they are greatly affected by adjacent grain orientations.
On the other hand, the {100} plane is the cubic orientation
{100}<100>, and this group of orientations is well known as a
component that decreases the r value which is the plastic strain
ratio, thus, it is easy to make the strain in the thickness
direction. Specifically, at the time of bending deformation, the
critical shear stress is equal in those slip systems that are
active under conditions in which the stress is acting from tension
in a single axis to surface-strain tension in each individually
oriented grain, and moreover thickness stress readily occurs.
[0024] Accordingly, whether under single-axis tension conditions or
surface-strain tension conditions, in either the LD (Longitudinal
Direction: the direction parallel to the direction of rolling of
the material), or the TD (Transversal Direction: the direction
perpendicular to the direction of rolling of the material), there
is thought to be an orientation in which a large strain is applied
in the thickness direction, and there is a high probability of this
becoming a starting point for an indentation during bending
deformation, so suppressing the generation of grains having this
orientation or dispersing them finely, or even if generation in
this orientation is unavoidable, dispersing them uniformly at as
small as possible of interval is thought to lead to improved
bending workability.
[0025] Here, in the case of metals having the FCC (face-centered
cubic) structure such as copper-based alloys, in x-ray diffraction,
the x-ray diffraction intensities (or simply the diffraction
intensities) of the {110} plane, {111} plane, {311} plane and {100}
plane are represented by I{220}, I{111}, I{311} and I{200},
respectively.
[0026] Considering the above, as a result of extensive research in
order to solve the problems of the background art, the diffraction
intensity I{220} of the {110} plane, the diffraction intensity
I{111} of the {111} plane, the diffraction intensity I{311} of the
{311} plane and the diffraction intensity I{200} of the {100} plane
were measured and improvement of the bending workability was
achieved by introducing the parameter S.sub.ND defined as:
S.sub.ND=I{200}/[I{111}+I{220}+I{311}] and controlling texture
using this as an index. Namely, the shape of the surface of bends
was good when 0.05.ltoreq.S.sub.ND.ltoreq.0.15.
[0027] On the other hand, when S.sub.ND<0.05, the orientation
plane density of the {110} plane for a representative becomes too
high, and because these grains develop to form a group, this leads
to localization of surface wrinkles during bending deformation and
causes cracks on the surface. When S.sub.ND>0.15, coarse grains
with an orientation in the {100} plane have a spotty distribution,
leading to localization of surface wrinkles during bending
deformation and as a result wide wrinkles occur and moreover, the
tensile strength does not reach 500 N/mm.sup.2, so it is not suited
to the molding and mounting of small pins. In addition, if one
emphasizes the bending deformation characteristics, then it is
preferable that 0.1.ltoreq.S.sub.ND.ltoreq.0.15.
[0028] Next, the range of constituents in the composition of the
copper-based alloy according to the present invention is defined to
be: Ni, Sn, P and also at least one or more elements selected from
a group consisting of Zn, Si, Fe, Co, Mg, Ti, Cr, Zr and Al in a
total amount of 0.01-30 wt. % with the remainder being Cu and
unavoidable impurities. This composition is adopted because it
maintains the balance among conductivity, tensile strength and 0.2%
yield strength of the material and further increases the bending
workability.
[0029] If the total amount of the Ni, Sn, P and also at least one
or more elements selected from a group consisting of Zn, Si, Fe,
Co, Mg, Ti, Cr, Zr and Al is less than 0.01 wt. %, while the
conductivity increases, satisfactory tensile strength, 0.2% proof
tress and other properties are difficult to obtain. In addition,
while the tensile strength and 0.2% proof tress can be increased by
raising the percent reduction to 98%, the bending workability
deteriorates greatly. On the other hand, if the total amount of the
Ni, Sn, P and also at least one or more elements selected from a
group consisting of Zn, Si, Fe, Co, Mg, Ti, Cr, Zr and Al exceeds
30 wt. %, although the tensile strength and 0.2% yield strength can
be increased, the conductivity is lowered and the bending
workability also deteriorates.
[0030] Accordingly, the range of constituents in the composition of
the copper-based alloy according to the present invention is
defined to be a copper-based alloy containing: Ni, Sn, P and also
at least one or more elements selected from a group consisting of
Zn, Si, Fe, Co, Mg, Ti, Cr, Zr and Al in a total amount of 0.01-30
wt. % with the remainder being Cu and unavoidable impurities.
[0031] In addition, if the range of constituents in the composition
is defined not as above but rather as containing Ni: 0.01-4.0 wt.
%, Sn: 0.01-10 wt. % and P: 0.01-0.20 wt. % and also at least one
or more elements selected from a group consisting of Zn, Si, Fe,
Co, Mg, Ti, Cr, Zr and Al in a total amount of 0.01-30 wt. % with
the remainder being Cu and unavoidable impurities, then among the
above reasons, the grounds for and effect of the limitations on
constituent elements and their content and such still apply if "Ni,
Sn, P and also at least one or more elements selected from a group
consisting of Zn, Si, Fe, Co, Mg, Ti, Cr, Zr and Al" is read as "at
least one or more elements selected from a group consisting of Zn,
Si, Fe, Co, Mg, Ti, Cr, Zr and Al."
[0032] In addition to the elements listed above as defined by the
present invention, if at least one element selected from a group of
elements consisting of, for example, Ag, Au, Bi, In, Mn, La, Pb,
Pd, Sb, Se, Te and Y is present in a total amount of 2 wt. % or
less, and contained as an additional element as defined by the
present invention, then it may take a role in increasing the
bending workability and will not impede the meritorious effects
obtained.
[0033] An explanation will now be given regarding the main added
elements as defined according to the present invention.
(1) Sn
[0034] Sn is a mandatory element for achieving both bending
workability and strength and elasticity.
[0035] When Sn is in solid solution within a Cu matrix, it can
greatly reduce the degree of concentration of the {100} planes that
affects bending workability, and moreover it increases the degree
of concentration of the {110} planes and {311} planes in
combination with working and heat treatment, and furthermore it can
make the grains having {100} planes fine and uniformly distributed,
and as a result the bending workability can be increased. In
addition, it can increase the strength and elasticity at the same
time. However, if the Sn content is less than 0.01 wt. %, then
these meritorious effects are not sufficiently obtained but on the
other hand if the Sn content exceeds 10 wt. %, then the drop in
electrical conductivity becomes marked and this can have
deleterious effects on the ease of casting and hot workability. In
addition, Sn is expensive, so this would be disadvantageous from an
economic standpoint. Accordingly, the Sn content is set as 0.01-10
wt. %, preferably 0.3-3.0 wt. % or more preferably 0.5-2.0 wt.
%.
(2) Ni
[0036] When Ni is in solid solution within a Cu matrix, it
increases the strength, elasticity and solderability, and moreover,
forms a compound with P or Si in some cases and precipitates out,
thus increasing the electrical conductivity and increasing the
strength and elasticity. In addition, it is an element that also
contributes to improving the heat resistance and stress relaxation
characteristics. However, if the Ni content is less than 0.01 wt.
%, then these meritorious effects are not sufficiently obtained but
on the other hand if the Ni content exceeds 4.0 wt. %, then the
drop in electrical conductivity becomes marked even in the
co-presence of P or Si in certain cases and this would be
disadvantageous from an economic standpoint. Accordingly, the Ni
content is set as 0.01-4.0 wt. % or preferably 0.5-3.0 wt. %.
(3) P
[0037] P acts as a deoxidizer in the melt during melting and
casting and also forms a compound with Ni or in some cases Fe or Mg
or Co, thus increasing the electrical conductivity and increasing
the strength and elasticity. However, if the P content is less than
0.01 wt. %, then these meritorious effects are not sufficiently
obtained but on the other hand if the P content exceeds 0.20 wt. %,
then the drop in electrical conductivity becomes marked even in the
co-presence of Ni or in some cases Fe or Mg or Co, and the solder
weatherability (atmospheric resistance of soft solder) deteriorates
markedly. This would also have deleterious effects on the hot
workability. Accordingly, the P content is set as 0.01-0.20 wt. %
or preferably 0.03-0.10 wt. %.
(4) Zn
[0038] When in solid solution within a Cu matrix, Zn has the effect
of increasing the strength and elasticity and enhancing the melt
deoxidizing effect, and also has the effect of reducing the
dissolved oxygen elements in the Cu matrix, and also has the effect
of increasing the solder weatherability and migration resistance.
However, if the Zn content is less than 0.01 wt. %, then these
meritorious effects are not sufficiently obtained but on the other
hand if the Zn content exceeds 30 wt. %, then not only will the
electrical conductivity drop but solderability will drop and also
even in combination with other elements, the susceptibility to
stress-corrosion cracking becomes heightened, and this is not
preferable. Accordingly, the Zn content is set as 0.01-30 wt. %,
more preferably 0.01-10 wt. % and even more preferably 0.03-3.0 wt.
%.
(5) Si
[0039] When co-present with Ni, Si forms a compound and
precipitates out into the Cu matrix, and thus has the effect of
increasing strength and elasticity without greatly decreasing the
electrical conductivity. If the Si content is less than 0.01 wt. %,
then these meritorious effects are not sufficiently obtained but on
the other hand if the Si content exceeds 1.0 wt. %, then the hot
workability drops markedly. Accordingly, the Si content is set as
0.01-1.0 wt. %.
(6) Fe, Co, Mg, Ti, Cr, Zr, Al
[0040] When in solid solution within a Cu matrix or when
precipitating to form a compound, these elements have the effect of
increasing the strength, elasticity and heat resistance, and also
increasing the ease of press-blanking. However, if the content is
less than 0.01 wt. %, then these meritorious effects are not
sufficiently obtained but on the other hand if the content exceeds
3.0 wt. %, then the drop in electrical conductivity will be marked
and the heat treatment temperature at the time of manufacture will
become high, so this is disadvantageous from an economic
standpoint. Accordingly, the content of one or two or more of the
aforementioned elements is preferably 0.01-3.0 wt. %.
(7) Oxygen
[0041] If oxygen is present in large amounts, then oxides of Si,
Fe, Mg, P and the like are formed, and a second phase is
preferentially generated at the grain boundaries, so there is a
risk of deterioration of the plating reliability and various other
properties of the copper-based alloy according to the present
invention, so the oxygen content is set to 20 ppm or less.
[0042] Next, explanation will be made regarding the reasons why the
various processing steps including the heat treatment of the
copper-based alloy according to the present invention are limited
as above.
[0043] The material according to the present invention can be
manufactured by the following process. Namely, take an ingot of a
copper-based alloy having the indicated elemental composition, and
perform cold rolling and annealing until the prescribed sheet
thickness is obtained, and then perform a combination of cold
rolling at a percent reduction Z that satisfies the above Formula
(1) followed by low-temperature annealing performed at a
temperature below the recrystallization temperature, to obtain
material of the desired sheet thickness.
[0044] When homogenization annealing or hot rolling is performed in
advance before cold-rolling the ingot, this has the meritorious
effect of removing micro or macro segregations of the solute
elements that occurred during casting, thus homogenizing the solute
element distribution, and in particular, performing hot rolling can
make the crystal orientations of the ingot random and make the
grains fine and uniform, and moreover this is economically
advantageous because the percent rolling reduction can be greatly
increased. Accordingly, it is preferable for the ingot to be
subjected to at least one of homogenization annealing or hot
rolling in advance prior to cold rolling. The homogenization
annealing and hot rolling should preferably be performed at
750.degree. C.-900.degree. C. for 30 minutes to 2 hours.
Z<100-10X-Y (1) [Here, Z is the percent cold reduction (%), X is
the Sn content (wt. %) among the various elements, and Y is the
total content (wt. %) of all elements other than Sn and Cu.]
0.8(100-10X-Y)<Z<100-X-Y (2); [Here, Z is the percent cold
reduction (%), X is the Sn content (wt. %) among the various
elements, and Y is the total content (wt. %) of all elements other
than Sn and Cu.]
[0045] The percent cold reduction Z (%) is set as given in Formula
(1) because performing cold rolling at a percent reduction that
satisfies Formula (1) for each of the added elements reduces the
{100} planes that may become the starting points of surface
wrinkles during bending deformation in the ND plane, and also
simultaneously suppresses the degree of concentration of {110}
planes, {111} planes and {311} planes, and particularly the {110}
planes that cause deterioration of bending workability in the
surface-strain tensile stress state, and thus suppresses the
deterioration of bending workability. The S.sub.ND at this time is
such that S.sub.ND.gtoreq.0.05. In addition, the limitation as
given in Formula (2) is made because, when cold rolling is
performed with a percent reduction in a range that satisfies
Formula (2), variations in the degrees of concentration of the
{100} planes, {110} planes, {111} planes and {311} planes are small
and stable. The S.sub.ND at this time is such that it satisfies the
relation 0.05.ltoreq.S.sub.ND.ltoreq.0.15. Moreover, the tensile
strength and 0.2% yield strength are improved, while good strength,
0.2% yield strength and bending workability that typically have a
tradeoff relationship are both achieved. In addition, when
low-temperature annealing is performed below the recrystallization
temperature after the final cold rolling, there is virtually no
change in the ratio of concentration of the {100} planes, {110}
planes, {111} planes and {311} planes, and the tensile strength and
0.2% yield strength are also maintained. Moreover, improved
elongation, namely bendability, can be achieved by low-temperature
annealing.
[0046] Accordingly, it is preferable to perform cold rolling at a
percent cold reduction Z (%) that satisfies Formula (1), and even
more preferable to perform a combination of cold rolling at a
percent cold reduction Z (%) that satisfies Formula (2) and
low-temperature annealing at a temperature below the
recrystallization temperature. The low-temperature annealing
conditions at this time are that annealing be performed preferably
at a temperature 50-250.degree. C. below the recrystallization
temperature of the copper-based alloy for 30 minutes to 2 hours,
for example, at a temperature of 250-350.degree. C. for 30 minutes
to 1 hour, but even outside of these conditions, the desired
characteristics can be achieved with temperature and time
combinations that apply roughly the same amount of heat to the
material.
[0047] On the other hand, at percent cold reductions that do not
satisfy Formula (1), the degree of concentration of {100} planes
decreases greatly while the degree of concentration of {110}
markedly increases, thus causing great deterioration in the bending
workability in the surface stress state. The S.sub.ND at this time
is such that S.sub.ND.ltoreq.0.05. If one attempts to increase the
bending workability even further, then the tensile strength and
0.2% yield strength deteriorate and the balance between the two is
not maintained.
[0048] As typical examples of the phenomena described above,
consider the relationship between the percent reduction of an alloy
of Cu--1.04 wt. % Ni--0.90 wt. % Sn--0.05 wt. % P and the degree of
concentration of various crystal orientations in the ND plane, and
the relationship between the percent reduction of an alloy of
Cu--1.04 wt. % Ni--0.90 wt. % Sn--0.05 wt. % P and the tensile
strength, 0.2% yield strength and elongation. At this time, the
percent cold reduction Z (%) that satisfies Formula (1) is
Z<89.91%. Moreover, the percent cold reduction that satisfies
Formula (2) is 71.9%<Z<89.91%. At Z<89.91% and
particularly at 71.9%<Z<89.91%, the degree of concentration
of {100} planes that become the starting points of surface wrinkles
during bending deformation is virtually unchanged. At the same
time, the degree of concentration of the {110} planes, which causes
marked degradation of the bending workability in the surface-strain
tensile stress state, is nearly constant over this region. The
S.sub.ND at this time is S.sub.ND=0.10 at a percent reduction of
80%, and S.sub.ND=0.07 at 85%. In addition, improvements in the
tensile strength and 0.2% yield strength are achieved. When the
percent reduction exceeds 90%, although the elongation obtained by
tensile testing increases, when compared to bend testing, when the
width to thickness ratio W/t of the sheet is W/t.ltoreq.4 in the
single-axis tensile stress state, the bending workability improves,
but at W/t.gtoreq.10 in the surface-strain tensile stress state,
the bending workability deteriorates markedly so the results are
not comparable to the elongation obtained by tensile testing.
[0049] Next, explanation will be made regarding why the various
processing steps including the heat treatment of the copper-based
alloy according to the present invention are limited as set out
above.
[0050] The material according to the present invention can be
manufactured by the following process. Namely, take an ingot of a
copper-based alloy having the indicated elemental composition, and
perform a combination process of cold rolling followed by annealing
at least one or more times, and then perform intermediate rolling,
which is a rolling process before the final cold rolling process,
thereby making the x-ray diffraction intensity ratio of the sheet
surface S.sub.ND such that 0.05.ltoreq.S.sub.ND.ltoreq.0.15, and
thereafter perform annealing to obtain sheet with a grain size of
20 .mu.m or less, and then performing the final cold rolling and
low-temperature annealing at a temperature below the
recrystallization temperature.
[0051] When homogenization annealing or hot rolling is performed in
advance before cold-rolling the ingot, this has the meritorious
effect of removing micro or macro segregations in the solute
elements that occurred during casting, thus homogenizing the solute
element distribution, and in particular, performing hot rolling can
make the crystal orientations of the ingot random and make the
grains fine and uniform, and moreover this is economically
advantageous because the percent rolling reduction can be greatly
increased. Accordingly, it is preferable for the ingot to be
subjected to at least one of homogenization annealing or hot
rolling in advance prior to cold rolling. The homogenization
annealing and hot rolling should preferably be performed at
750.degree. C.-900.degree. C. for 30 minutes to 2 hours.
[0052] When the combination process of cold rolling (preferably
cold rolling to 50-90% reduction, and more preferably 55-85%
reduction) followed by annealing is performed at least one or more
times, and then the intermediate rolling, which is a rolling
process before the final cold rolling process, is performed,
thereafter the x-ray diffraction intensity ratio of the sheet
surface S.sub.ND is preferably 0.05.ltoreq.S.sub.ND.ltoreq.0.15. If
0.05.ltoreq.S.sub.ND.ltoreq.0.15, then in the annealing performed
immediately thereafter the grain distribution becomes uniform if
the annealing is performed above the recrystallization temperature.
Here, if the temperature and time of the annealing are controlled
(preferably to 400-700.degree. C. and 0.5 minutes to 10 hours) so
that the grain size becomes 20 .mu.m or less after the annealing,
the sheet obtained from the combination of the final cold rolling
and annealing below the recrystallization temperature has improved
bending workability while maintaining high strength.
[0053] Here, when S.sub.ND>0.15, the temperature and time
domains required to obtain the texture described above in the
subsequent annealing become narrow and control of the grain size
becomes difficult, and moreover, this increases the degree of
concentration of {100} planes that become the starting points of
indentations during bending deformation in the ND plane, and coarse
grains with this orientation have a spotty distribution. On the
other hand, when 0.05>SAD, the orientation plane density of the
{110} plane for a representative becomes too high, and because
these grains develop to form a group, this leads to localization of
surface wrinkles during bending deformation. In addition, if the
grain size after the annealing that follows intermediate rolling
exceeds 20 .mu.m, then the percent reduction in the final cold
rolling required to obtain the required strength becomes
excessively large and the bending workability deteriorates.
[0054] By the foregoing there is obtained a
precipitation-strengthened type copper-based alloy with a superior
balance of conductivity, tensile strength, 0.2% yield strength,
springiness, Vickers hardness and bending workability.
Specifically, the characteristics with superior balance are a
conductivity of 25.0% IACS or greater, or preferably 35.0% IACS or
greater, a tensile strength of 560 N/mm.sup.2 or greater, or
preferably 580 N/mm.sup.2 or greater, a 0.2% yield strength of 550
N/mm.sup.2 or greater, or preferably 570 N/mm.sup.2 or greater, a
spring deflection limit of 400 N/mm.sup.2 or greater, or preferably
460 N/mm.sup.2 or greater, a Vickers hardness of 180 or preferably
190 or greater, and a bending workability (180.degree. bendability
R/t) of 1.0 or less, preferably 0.5 or less or even more preferably
0.
EXAMPLES
[0055] The present invention will now be explained with reference
to working examples but the technical scope of the present
invention is in no way limited thereto.
Examples 1-10 and Comparative Examples 11-15
[0056] Copper-based alloys numbered 1-15 with their chemical
compositions (wt. %) presented in Table 1 were melted in an Ar
atmosphere and cast into 40 40 100 (mm) ingots using a carbon ingot
mold. The ingots thus obtained were cut into 40 40 20 (mm) slices
and then subjected to homogenization heat treatment at 900.degree.
C. for one hour. Thereafter, the slices were hot-rolled from a
sheet thickness of 20 mm to 6.0 mm and then water-quenched and
pickled after rolling. The details of the conditions for the
respective sheets numbered 1-15 thus obtained are presented
below.
[0057] Invention Example No. 1 was cold-rolled from a thickness of
6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one hour.
Thereafter, it was cold-rolled from a thickness of 2.5 mm to 1.2 mm
and heat-treated at 500.degree. C. for one hour. The sheet thus
obtained was given a finish cold-rolling from a thickness of 1.2 mm
to 0.2 mm and then heat-treated for one hour at 300.degree. C.,
which is below the recrystallization temperature.
[0058] Invention Example No. 2 was cold-rolled from a thickness of
6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one hour.
Thereafter, it was cold-rolled from a thickness of 2.5 mm to 0.8 mm
and heat-treated at 500.degree. C. for one hour. The sheet thus
obtained was given a finish cold-rolling from a thickness of 0.8 mm
to 0.2 mm and then heat-treated for one hour at 300.degree. C.,
which is below the recrystallization temperature.
[0059] Invention Example No. 3 was cold-rolled from a thickness of
6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one hour.
Thereafter, it was cold-rolled from a thickness of 2.5 mm to 1.0 mm
and heat-treated at 500.degree. C. for one hour. The sheet thus
obtained was given a finish cold-rolling from a thickness of 1.0 mm
to 0.2 mm and then heat-treated for one hour at 300.degree. C.,
which is below the recrystallization temperature.
[0060] Invention Example No. 4 was cold-rolled from a thickness of
6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one hour.
Thereafter, it was cold-rolled from a thickness of 2.5 mm to 1.2 mm
and heat-treated at 500.degree. C. for one hour. The sheet thus
obtained was given a finish cold-rolling from a thickness of 1.2 mm
to 0.2 mm and then heat-treated for one hour at 300.degree. C.,
which is below the recrystallization temperature.
[0061] Invention Example No. 5 was cold-rolled from a thickness of
6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one hour.
Thereafter, it was cold-rolled from a thickness of 2.5 mm to 1.0 mm
and heat-treated at 500.degree. C. for one hour. The sheet thus
obtained was given a finish cold-rolling from a thickness of 1.0 mm
to 0.2 mm and then heat-treated for one hour at 300.degree. C.,
which is below the recrystallization temperature.
[0062] Invention Example No. 6 was cold-rolled from a thickness of
6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one hour.
Thereafter, it was cold-rolled from a thickness of 2.5 mm to 1.2 mm
and heat-treated at 500.degree. C. for one hour. The sheet thus
obtained was given a finish cold-rolling from a thickness of 1.2 mm
to 0.2 mm and then heat-treated for one hour at 300.degree. C.,
which is below the recrystallization temperature.
[0063] Invention Example No. 7 was cold-rolled from a thickness of
6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one hour.
Thereafter, it was cold-rolled from a thickness of 2.5 mm to 0.6 mm
and heat-treated at 500.degree. C. for one hour. The sheet thus
obtained was given a finish cold-rolling from a thickness of 0.6 mm
to 0.2 mm and then heat-treated for one hour at 300.degree. C.,
which is below the recrystallization temperature.
[0064] Invention Example No. 8 was cold-rolled from a thickness of
6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one hour.
Thereafter, it was cold-rolled from a thickness of 2.5 mm to 0.6 mm
and heat-treated at 500.degree. C. for one hour. The sheet thus
obtained was given a finish cold-rolling from a thickness of 0.6 mm
to 0.2 mm and then heat-treated for one hour at 300.degree. C.,
which is below the recrystallization temperature.
[0065] Invention Examples No. 9-10 were cold-rolled from a
thickness of 6.0 mm to 2.5 mm and heat-treated at 550.degree. C.
for one hour. Thereafter, they were cold-rolled from a thickness of
2.5 mm to 0.8 mm and heat-treated at 500.degree. C. for one hour.
The sheets thus obtained were given a finish cold-rolling from a
thickness of 0.8 mm to 0.2 mm and then heat-treated for one hour at
300.degree. C., which is below the recrystallization
temperature.
[0066] On the other hand, Comparative Example No. 11 was
cold-rolled from a thickness of 6.0 mm to 2.5 mm and heat-treated
at 550.degree. C. for one hour. Thereafter, it was cold-rolled from
a thickness of 2.5 mm to 0.3 mm and heat-treated at 500.degree. C.
for one hour. The sheet thus obtained was given a finish
cold-rolling from a thickness of 0.3 mm to 0.2 mm and then
heat-treated for one hour at 300.degree. C., which is below the
recrystallization temperature.
[0067] Comparative Example No. 12 was cold-rolled from a thickness
of 6.0 mm to 1.0 mm and heat-treated at 550.degree. C. for one
hour. Thereafter, it was cold-rolled from a thickness of 1.0 mm to
0.6 mm and heat-treated at 500.degree. C. for one hour. The sheet
thus obtained was given a finish cold-rolling from a thickness of
0.6 mm to 0.2 mm and then heat-treated for one hour at 300.degree.
C., which is below the recrystallization temperature.
[0068] Comparative Example No. 13 was cold-rolled from a thickness
of 6.0 mm to 0.5 mm and heat-treated at 600.degree. C. for one
hour. The sheet thus obtained was given a finish cold-rolling from
a thickness of 0.5 mm to 0.2 mm and then heat-treated for one hour
at 300.degree. C., which is below the recrystallization
temperature.
[0069] Comparative Example No. 14 was cold-rolled from a thickness
of 6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one
hour. The sheet thus obtained was given a finish cold-rolling from
a thickness of 2.5 mm to 0.2 mm and then heat-treated for one hour
at 250.degree. C., which is below the recrystallization
temperature.
[0070] Comparative Example No. 15 was cold-rolled from a thickness
of 6.0 mm to 2.5 mm and heat-treated at 550.degree. C. for one
hour. The sheet thus obtained was given a finish cold-rolling from
a thickness of 2.5 mm to 0.2 mm and then heat-treated for one hour
at 350.degree. C., which is below the recrystallization
temperature. TABLE-US-00001 TABLE 1 Process condition Thickness
Percent Percent Thickness after reduction in Thickness reduction
Low- after rough Rough intermediate intermediate Finish after
finish in finish temperature Chemical composition (wt. %)
cold-rolling annealing cold-rolling cold-rolling annealing
cold-rolling cold-rolling Z.sub.min, Z.sub.max .sup.* anneal
Examples Sn Ni P Other Cu (mm) (conditions) (mm) (%) (conditions)
(mm) (%) (%) (conditions) Invention No. 1 0.52 1.02 0.05 Rem 2.5
550.degree. C., 1 h 1.2 52.0 500.degree. C., 1 h 0.2 83.3 75.0,
93.7 300.degree. C., 1 h No. 2 0.90 1.04 0.05 Rem 2.5 550.degree.
C., 1 h 0.8 68.0 500.degree. C., 1 h 0.2 75.0 71.9, 89.9
300.degree. C., 1 h No. 3 0.90 1.04 0.05 Rem 2.5 550.degree. C., 1
h 1.0 60.0 500.degree. C., 1 h 0.2 80.0 71.9, 89.9 300.degree. C.,
1 h No. 4 0.95 0.95 0.06 Zn:0.10 Rem 2.5 550.degree. C., 1 h 1.2
52.0 500.degree. C., 1 h 0.2 83.3 71.5, 89.4 300.degree. C., 1 h
No. 5 1.52 0.95 0.05 Rem 2.5 550.degree. C., 1 h 1.0 60.0
500.degree. C., 1 h 0.2 80.0 67.3, 84.1 300.degree. C., 1 h No. 6
0.95 0.60 0.05 Rem 2.5 550.degree. C., 1 h 1.2 52.0 500.degree. C.,
1 h 0.2 83.3 71.9, 89.9 300.degree. C., 1 h No. 7 1.95 0.55 0.06
Zn:0.08 Rem 2.5 550.degree. C., 1 h 0.6 76.0 500.degree. C., 1 h
0.2 66.7 63.8, 79.8 300.degree. C., 1 h Fe:0.05 No. 8 1.75 0.98
0.05 Rem 2.5 550.degree. C., 1 h 0.6 76.0 500.degree. C., 1 h 0.2
66.7 65.2, 81.5 300.degree. C., 1 h No. 9 1.74 1.55 0.07 Rem 2.5
550.degree. C., 1 h 0.8 68.0 500.degree. C., 1 h 0.2 75.0 64.8,
81.0 300.degree. C., 1 h No. 10 1.52 2.05 0.10 Rem 2.5 550.degree.
C., 1 h 0.8 68.0 500.degree. C., 1 h 0.2 75.0 66.1, 82.7
300.degree. C., 1 h Comparative No. 11 0.90 1.04 0.05 Rem 2.5
550.degree. C., 1 h 0.3 -- 500.degree. C., 1 h 0.2 33.3 71.9, 89.9
300.degree. C., 1 h Example No. 12 0.89 1.02 0.05 Rem 1.0
550.degree. C., 1 h 0.6 -- 500.degree. C., 1 h 0.2 66.7 72.0, 90.0
300.degree. C., 1 h No. 13 0.85 1.05 0.07 Zn:0.10 Rem 0.5
600.degree. C., 1 h -- -- -- 0.2 60.0 72.1, 90.2 300.degree. C., 1
h Fe:0.10 No. 14 0.95 0.98 0.06 Zn:0.10 Rem 2.5 550.degree. C., 1 h
-- -- -- 0.2 92.0 71.5, 89.4 250.degree. C., 1 h No. 15 0.85 1.10
0.05 Rem 2.5 550.degree. C., 1 h -- -- -- 0.2 92.0 72.3, 90.4
350.degree. C., 1 h .sup.*: Calculation formulae as recited in this
patent: Zn.sub.min 0.8 (100 - 10X - Y), Zn.sub.max 100 - 10X -
Y
[0071] Examples No. 1-10 obtained as described above had an average
grain size of 6-10 .mu.m after the 500.degree. C. 1 hour heat
treatment before the final cold rolling, and this was below 20
.mu.m, and when x-ray diffraction of the sheet surface (ND plane)
was performed prior to this heat treatment and the S.sub.ND was
measured, it was found to be 0.06-0.10, or within the range
0.05.ltoreq.S.sub.ND.ltoreq.0.15.
[0072] Here, the x-ray diffraction intensity measurement conditions
are as follows.
[0073] X-ray tube: Cu, tube voltage: 40 kV, tube current: 30 mA,
sampling interval: 0.020.degree., monochromator used, specimen
holder: Al
[0074] Note that the x-ray diffraction intensity measurement
conditions are not limited to the conditions above, but rather they
can be modified appropriately depending on the type of sample.
[0075] In addition, the grain size is calculated in the present
invention based on the JIS H 0501 standard for grains observed on
the sample surface (rolled surface) using an optical microscope at
a magnification of 200.
[0076] The samples No. 1-15 thus obtained each had dispersed and
precipitated Ni--P compounds, but first these samples No. 1-15 were
evaluated by measuring the S.sub.ND. Then their conductivity,
tensile strength and 180.degree. bendability were evaluated. The
conductivity and tensile strength were evaluated by measurements
based on the JIS H 0505 and JIS Z 2241 standards, respectively. In
addition, the bendability was evaluated based on a 180.degree. bend
test (JIS H 3110), where a 10-mm wide test piece is blanked in a
direction parallel to the rolling direction and the bend inside
radius R and sheet thickness t are measured to find the ratio R/t,
and the test pieces thus obtained are evaluated based on the
smallest value of R/t at which no cracks occurred on the surface of
the bend. The results are presented in Table 2. TABLE-US-00002
TABLE 2 Grain S.sub.ND size after 180.degree. prior to finish
anneal S.sub.ND of Tensile bendability Chemical composition (wt. %)
finish anneal (.mu.m) final sheet Conductivity strength R/t.sup.*
Examples Sn Ni P Other Cu (0.05-0.15) (.ltoreq.20 .mu.m)
(0.05-0.15) (% IACS) (N/mm.sup.2) (0.degree. direction) Invention
No. 1 0.52 1.02 0.05 Rem 0.10 10 0.09 48.2 580 0.5 No. 2 0.90 1.04
0.05 Rem 0.10 8 0.11 40.5 595 0 No. 3 0.90 1.04 0.05 Rem 0.10 8
0.09 40.2 600 0 No. 4 0.95 0.95 0.06 Zn:0.10 Rem 0.10 8 0.07 39.3
615 0.5 No. 5 1.52 0.95 0.05 Rem 0.10 8 0.07 35.4 635 0.5 No. 6
0.95 0.60 0.05 Rem 0.08 10 0.11 43.5 600 0 No. 7 1.95 0.55 0.06
Zn:0.08 Rem 0.06 6 0.10 33,8 625 0.5 Fe:0.05 No. 8 1.75 0.98 0.05
Rem 0.07 7 0.09 33.5 610 0.5 No. 9 1.74 1.55 0.07 Rem 0.07 10 0.06
29.8 645 1.0 No. 10 1.52 2.05 0.10 Rem 0.07 8 0.07 28.5 635 1.0
Comparative No. 11 0.90 1.04 0.05 Rem 0.07 8 0.16 40.5 490 0.5
Example No. 12 0.89 1.02 0.05 Rem 0.16 25 0.17 41.5 540 2 Zn:0.10
No. 13 0.85 1.05 0.07 Rem 0.03 25 0.18 41.5 540 2 Fe: 0.10 No. 14
0.95 0.98 0.06 Zn:0.10 Rem 0.14 10 0.04 40.2 645 2.5 No. 15 0.85
1.10 0.05 Rem 0.15 10 0.03 41.0 565 1.5 .sup.* : The minimum R/t at
which no cracks occur when the thickness of the test piece is t mm,
the width is W mm (W/t = 50) and the bend inside radius is R
mm.
[0077] The following is clear from the results of Table 1 and Table
2.
[0078] Alloys No. 1-10 according to the present invention have an
S.sub.ND prior to the finish annealing of 0.06-0.10, so this
satisfies the condition 0.05.ltoreq.S.sub.ND.ltoreq.0.15, and the
grain size after the subsequent annealing is 6-10 .mu.m, so this
satisfies the condition of being less than 20 .mu.m, and the final
sheet also has an S.sub.ND of 0.06-0.11, so this satisfies the
condition 0.05.ltoreq.S.sub.ND.ltoreq.0.15, and they had superior
bending workability and had a superior balance of conductivity and
tensile strength.
[0079] On the other hand, Comparative Example No. 11 had a finish
rolling percent reduction after the finish annealing that did not
satisfy the lower limit of Formula (2), and while its bending
workability was satisfactory, its tensile strength was 490
N/mm.sup.2 which was inferior to the tensile strength of Examples
No. 1-10 according to the present invention.
[0080] Comparative Examples No. 12 and 13 have a grain size after
final annealing in excess of 20 .mu.m, and their tensile strength
was low at 540 N/mm.sup.2 and their bending workability was also
inferior.
[0081] Comparative Examples No. 14 and 15 have a finish rolling
percent reduction after the finish annealing that did not satisfy
the upper limit of Formula (2), and while No. 14 exhibited a high
value of 645 N/mm.sup.2 for its tensile strength, its bending
workability is inferior. No. 15 was aiming for improved bending
workability by increasing the low-temperature annealing temperature
by 100.degree. C. over that of No. 14, but the bending workability
was not improved as much as one would think and the tensile
strength dropped to 565 N/mm.sup.2.
Example 2
[0082] Alloy No. 3 according to the present invention presented in
Table 1 of Example 1 (with a sheet thickness of 0.20 mm) and a
commercial phosphor bronze alloy (C5191, grade H, sheet thickness
0.20 mm: 6.5 wt. % Sn, 0.2 wt. % P, remainder Cu) were subjected to
an evaluation of their conductivity, tensile strength, 0.2% yield
strength, springiness, Vickers hardness and bending
workability.
[0083] The measurement of the conductivity, tensile strength, 0.2%
yield strength, spring reflection limit and Vickers hardness were
performed according to the JIS H 0505, JIS Z 2241, JIS H 3130 and
JIS Z 2241 standards, respectively. The bending workability was
evaluated based on a 180.degree. bend test (JIS H 3110), where a
10-mm wide test piece is blanked in a direction parallel to the
rolling direction and the bend inside radius R and sheet thickness
t are measured to find the ratio R/t, and the test pieces thus
obtained are evaluated based on the smallest value of R/t at which
no cracks occurred on the surface of the bend. The results are
presented in Table 3. TABLE-US-00003 TABLE 3 Tensile 0.2% yield
Spring strength strength reflection limit Minimum S.sub.ND of the
(N/mm.sup.2) (N/mm.sup.2) (N/mm.sup.2) Vickers R/t.sup.* final
sheet Conductivity 0.degree., 90.degree. 0.degree., 90.degree.
0.degree., 90.degree. hardness 0.degree., 90.degree. (0.05- (%
IACS) directions directions directions (Hv) directions 0.15) Alloy
No. 40 600, 630 590, 600 460, 560 190 0, 2.0 0.09 3 of the present
invention C5 191 H 13 638, 642 634, 575 390, 540 195 0.5 ,2.0 0.03
.sup.*: The minimum R/t at which no cracks occur in the bend
surface when subjected to 90.degree. double bending.
[0084] From the results of Table 3, one can see that in comparison
to the conventional copper-based alloy C5191H typically used for
connectors, switches and relays, the copper-based alloy according
to the present invention had a markedly higher conductivity and
superior balance of tensile strength, 0.2% yield strength, spring
bending elastic limit, Vickers hardness and bending
workability.
[0085] The copper-based alloy according to the present invention
can be used in narrow-pitch connectors for use in
telecommunications, automotive harness connectors, semiconductor
lead frames and compact switches and relays and the like.
* * * * *