U.S. patent application number 12/935688 was filed with the patent office on 2011-02-03 for cu-ni-si-co-cr system alloy for electronic materials.
This patent application is currently assigned to JX Nippon Mining & Metals Corporation. Invention is credited to Naohiko Era, Hiroshi Kuwagaki.
Application Number | 20110027122 12/935688 |
Document ID | / |
Family ID | 41135511 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110027122 |
Kind Code |
A1 |
Era; Naohiko ; et
al. |
February 3, 2011 |
Cu-Ni-Si-Co-Cr System Alloy for Electronic Materials
Abstract
The problem to be solved by the present invention is to provide
a significant improvement in the properties in Cu--Ni--Co--Si alloy
by adding Cr, i.e., to provide Corson alloys having high strength
and high electrical conductivity. There is provided a copper alloy
for electronic materials comprising 1.0 to 4.5 mass % of Ni, 0.50
to 1.2 mass % of Si, 0.1 to 2.5 mass % of Co, 0.003 to 0.3 mass %
of Cr, with the balance being Cu and unavoidable impurities, the
mass concentration ratio of the total mass of Ni and Co to Si
([Ni+Co]/Si ratio) satisfies the formula:
4.ltoreq.[Ni+Co]/Si.ltoreq.5, and with regard to Cr--Si compound
whose size is 0.1 to 5 .mu.m dispersed in the material, atomic
concentration ratio of Cr to Si in the dispersed particle is 1-5,
and area dispersion density thereof is more than
1.times.10.sup.4/mm.sup.2, and not more than
1.times.10.sup.6/mm.sup.2.
Inventors: |
Era; Naohiko; ( Ibaraki,
JP) ; Kuwagaki; Hiroshi; (Ibaraki, JP) |
Correspondence
Address: |
DRINKER BIDDLE & REATH;ATTN: INTELLECTUAL PROPERTY GROUP
ONE LOGAN SQUARE, SUITE 2000
PHILADELPHIA
PA
19103-6996
US
|
Assignee: |
JX Nippon Mining & Metals
Corporation
Ibaraki
JP
|
Family ID: |
41135511 |
Appl. No.: |
12/935688 |
Filed: |
March 30, 2009 |
PCT Filed: |
March 30, 2009 |
PCT NO: |
PCT/JP2009/056537 |
371 Date: |
September 30, 2010 |
Current U.S.
Class: |
420/473 ;
420/481; 420/488 |
Current CPC
Class: |
C22C 9/06 20130101; C22C
9/10 20130101; H01L 2924/0002 20130101; H01L 2924/0002 20130101;
C22F 1/08 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
420/473 ;
420/481; 420/488 |
International
Class: |
C22C 9/06 20060101
C22C009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2008 |
JP |
2008-093780 |
Claims
1. A copper alloy for electronic materials comprising 1.0 to 4.5
mass % of Ni, 0.50 to 1.2 mass % of Si, 0.1 to 2.5 mass % of Co,
0.003 to 0.3 mass % of Cr, with the balance being Cu and
unavoidable impurities, the mass concentration ratio of the total
mass of Ni and Co to Si ([Ni+Co]/Si ratio) satisfies the formula:
4.ltoreq.[Ni+Co]/Si.ltoreq.5, and with regard to Cr--Si compound
particles whose size is 0.1 to 5 .mu.m dispersed in the material,
the atomic concentration ratio of Cr to Si in the dispersed
particle is 1-5, and area dispersion density thereof is more than
1.times.10.sup.4/mm.sup.2, and not more than
1.times.10.sup.6/mm.sup.2.
2. The copper alloy for electronic materials according to claim 1
wherein area dispersion density of the Cr--Si compound particles
whose size is more than 5 .mu.m dispersed in the material is not
more than 50/mm.sup.2.
3. The copper alloy for electronic materials according to claim 1
wherein the alloy further comprises one or more of Sn and Zn at
0.05-2.0 mass %.
4. The copper alloy for electronic materials according to claim 1
wherein the alloy further comprises one or more of Mg, Mn, Ag, P,
As, Sb, Be, B, Ti, Zr, Al and Fe at 0.001-2.0 mass %.
5. A wrought copper alloy product made of the copper alloy
according to any one of claims 1-4.
6. Electronic components comprising the copper alloy according to
any one of claims 1-4.
7. Electronic components comprising a wrought copper alloy product
according to claim 5.
Description
TECHNICAL FIELD
[0001] The present invention relates to precipitation hardening
copper alloys, in particular, to Cu--Ni--Si--Co--Cr system alloys
suitable for use in a variety of electronic components.
BACKGROUND ART
[0002] A copper alloy for electronic materials that are used in a
lead frame, connector, pin, terminal, relay, switch, and various
other electronic components is required to satisfy both high
strength and high electrical conductivity (or thermal conductivity)
as basic characteristics. In recent years, as high integration and
reduction in size and thickness of an electronic component have
been rapidly advancing, requirements for copper alloys used in
these electronic components have been increasingly becoming
severe.
[0003] Recently, because of considerations related to high strength
and high electrical conductivity, the amount in which
precipitation-hardened copper alloys are used has been increasing,
replacing conventional solid-solution strengthened copper alloys
typified by phosphor bronze and brass as copper alloys for
electronic components. With a precipitation-hardened copper alloy,
the aging of a solution-treated supersaturated solid solution
causes fine precipitates to be uniformly dispersed and the strength
of the alloys to increase. At the same time, the amount of solved
elements in the copper is reduced and electrical conductivity is
improved. For this reason, it is possible to obtain materials
having excellent strength, spring property, and other mechanical
characteristics, as well as high electrical and thermal
conductivity.
[0004] Among precipitation hardening copper alloys, Cu--Ni--Si
copper alloys commonly referred to as Corson alloys are typical
copper alloys having relatively high electrical conductivity,
strength, stress relaxation property, and bending workability, and
are among the alloys that are currently being actively developed in
the industry. In these copper alloys, fine particles of Ni--Si
intermetallic compounds are precipitated in the copper matrix,
thereby increasing strength and electrical conductivity.
[0005] It is known that characteristics of Cu--Ni--Si copper alloys
are improved by adding Co and Cr. Co and Cr are similar to Ni in
forming a compound with Si and increasing mechanical strength.
[0006] Japanese Patent Application Publication No. 2006-283120
(Patent Document 1) discloses that a dramatic improvement in the
properties (especially, the strength and electrical conductivity)
of a Co and Cr-containing Cu--Ni--Si alloy is achieved when the
size, composition and distribution of inclusion are controlled
under certain compositional and manufacturing condition.
Specifically, a Cu--Ni--Si--Co--Cr copper alloy for electronic
components is described in which the composition is 0.5 to 2.5 mass
% of Ni, 0.5 to 2.5 mass % of Co, and 0.30 to 1.2 mass % of Si,
0.09 to 0.5 mass % of Cr with the balance being Cu and unavoidable
impurities, the mass concentration ratio of the total mass of Ni
and Co to the mass of Si ([NH+Co]/Si ratio) in the alloy
composition satisfies the formula: 4.ltoreq.[Ni+Co]/Si.ltoreq.5,
the mass concentration ratio of Ni and Co (Ni/Co ratio) in the
alloy composition satisfies the formula 0.5.ltoreq.Ni/Co.ltoreq.2,
and with regard to the number of inclusion (P) whose size is 1
.mu.m or more dispersed in the material and the number of said
inclusion containing 10 mass % or more of carbon (Pc), Pc is 15 per
1000 .mu.m.sup.2 or less and the ratio (Pc/P) is 0.3 or less.
[0007] Japanese Patent Application Publication No. 2005-113180
(Patent Document 2) aims at the compound of Cr and Si which
precipitates in a copper alloy while it is not a Cu--Ni--Si copper
alloy. The Document says that when CrSi compound having a given
size and area number density is finely precipitated in Cu matrix
and the size of Cr compound other than CrSi is restricted,
etchability may be ensured while the punching quality is improved.
Further, a copper alloy having good etchability and punching
quality for electric components is described in which the
composition is 0.1 to 0.25 weight % of Cr, 0.005 to 0.1 weight % of
Si, 0.1 to 0.5 weight % of Zn, and 0.05 to 0.5 weight % of Sn, with
the balance being Cu and unavoidable impurities, the weight ratio
of Cr and Si is 3-25, CrSi compounds whose size is 0.05 .mu.m to 10
.mu.m are present in a copper matrix at area number density of
1.times.10.sup.3 to 5.times.10.sup.5/mm.sup.2, and the size of Cr
compounds (other than CrSi compound) is 10 .mu.m or less. The
Document discloses that for preparing said copper alloy, it is
necessary that the temperature for heating treatment before hot
working is 850 to 980.degree. C., and after said working, a process
comprising a cold working and a heat treatment at 400 to
600.degree. C. is performed one or more times.
[0008] [Patent Document 1] Japanese Patent Application Publication
No. 2006-283120
[0009] [Patent Document 2] Japanese Patent Application Publication
No. 2005-113180
DISCLOSURE OF INVENTION
Problem to be Solved by the Invention
[0010] In recent years, as high integration and reduction in size
and thickness of an electronic component have been rapidly
advancing, a dramatic improvement in properties of
Cu--Ni--Si--Co--Cr system alloy which is the alloy system according
to the present invention, is also required.
[0011] However, Patent Document 1 does not describe Cr--Si
compounds.
[0012] Patent Document 2 describes that controlling the area number
density and size of Cr--Si compounds improves the working
properties for etching and press-punching. However, in this
Document, Ni is not added, and therefore, it is merely required to
consider the conditions for preparing Cr--Si without considering
formation of Ni--Si compounds and Co--Si compounds. Therefore, in
this Document, it is not discussed how Cr--Si compounds should be
controlled in Cu--Ni--Si--Co--Cr system alloy.
[0013] Accordingly, the problem to be solved by the present
invention is to improve the properties of Cu--Ni--Si--Co--Cr system
alloy by controlling the state of precipitation of Cr--Si compounds
in said alloy.
Means for Solving the Problem
[0014] The present inventors conducted thoroughgoing research in
order to solve the above-described problems, and have found the
following inventions. The present invention provides
Cu--Ni--Si--Co--Cr system alloy in which Si is in excess of Ni and
Co to ensure the precipitation of Ni silicide in the corresponding
amount of added Ni and Co silicide in the corresponding amount of
added Co for increasing the strength, while the excessive Si forms
compound with added Cr for obtaining high electric conductivity.
The important point of the present invention is to control the
growth of the compound from Cr and Si, in order to prevent the
shortage of Si, which is to be combined with Ni and Co, by
overgrowth of Cr--Si compound. Specifically, the present inventors
turned our attention to the composition and size of the Cr--Si
compound and area number density thereof, and thus, found that the
effect can be increased by controlling the temperature during the
heat treatment and rate of cooling.
[0015] Namely, the present inventions are as follows:
(1) A copper alloy for electronic materials in which the
composition is 1.0 to 4.5 mass % of Ni, 0.50 to 1.2 mass % of Si,
0.1 to 2.5 mass % of Co, 0.003 to 0.3 mass % of Cr, with the
balance being Cu and unavoidable impurities, the mass concentration
ratio of the total mass of Ni and Co to Si ([Ni+Co]/Si ratio)
satisfies the formula: 4.ltoreq.[Ni+Co]/Si.ltoreq.5, and with
regard to Cr--Si compound whose size is 0.1 to 5 .mu.m dispersed in
the material, atomic concentration ratio of Cr to Si in the
dispersed particle is 1-5, and area dispersion density thereof is
more than 1.times.10.sup.4/mm.sup.2, and not more than
1.times.10.sup.6/mm.sup.2 (2) The copper alloy for electronic
materials described in (1) wherein area dispersion density of the
Cr--Si compound whose size is more than 5 .mu.m dispersed in the
material is not more than 50/mm.sup.2 (3) The copper alloy for
electronic materials described in (1) or (2) wherein the alloy
further comprises one or more selected from Sn and Zn at 0.05-2.0
mass % (4) The copper alloy for electronic materials described in
any of (1)-(3) wherein the alloy further comprises one or more
selected from Mg, Mn, Ag, P, As, Sb, Be, B, Ti, Zr, Al and Fe at
0.001-2.0 mass % (5) A wrought copper alloy product made of the
copper alloy described any of (1)-(4). (6) Electronic components
comprising the copper alloy described any of (1)-(5).
EFFECT OF THE INVENTION
[0016] In accordance with the present invention, a
Cu--Ni--Si--Co--Cr system alloy for electronic materials having
improved strength and electrical conductivity can be obtained
because the effect of addition of Cr which is an element for alloy
is more effectively exerted.
PREFERRED EMBODIMENTS OF THE INVENTION
(1) Addition Amount of Ni, Co and Si
[0017] Ni, Co and Si form an intermetallic compound with
appropriate heat-treatment and make it possible to increase
strength without adversely affecting electrical conductivity.
Addition amount of Ni, Co and Si will be examined below,
respectively.
[0018] As for Ni and Co, it is necessary for the copper alloy for
electronic materials to include 1.0 to 4.5 mass % of Ni and 0.1-2.5
mass % of Co so that the alloy may satisfy an appropriate strength
and electrical conductivity. Preferably, the alloy should include
1.0 to 2.0 mass % of Ni and 1.0 to 2.0 mass % of Co, and more
preferably, 1.2 to 1.8 mass % of Ni and 1.2 to 1.8 mass % of Co.
However, when the addition amounts of Ni and Co are such that Ni is
less than 1.0 mass % and Co is less than 0.1 mass %, respectively,
the desired strength cannot be achieved, and conversely, the
addition amounts are such that Ni is greater than 4.5 mass % and Co
is greater than 2.5 mass %, respectively, higher strength can be
achieved, but electrical conductivity is dramatically reduced and
hot workability is furthermore impaired.
[0019] As for Si, it is necessary for the copper alloy for
electronic materials to include 0.30 to 1.2 mass % of Si so that
the alloy may satisfy an objective strength and electrical
conductivity. Preferably, the alloy should include 0.5 to 0.8 mass
% of Si. However, when the addition of Si is such that Si is less
than 0.3 mass %, the desired strength cannot be achieved, and
conversely, when the addition amount is such that Si is greater
than 1.2 mass %, higher strength can be achieved, but electrical
conductivity is dramatically reduced and hot workability is
furthermore impaired.
[0020] In the present invention, the weight concentration ratio of
the total amount of Ni and Co to Si ([Ni+Co]/Si) in the alloy
composition is further defined.
[0021] In the present invention, Ni/Si ratio is set at lower side
of specified range 3.ltoreq.Ni/Si.ltoreq.7 previously reported,
namely, Si is added slightly more than usual, and thereby, Ni and
Co are converted into Ni silicide and Co silicide thoroughly, and
thus, reduction of electrical conductivity caused by solid solution
of excess Ni and Co which do not contribute the precipitation may
be reduced. However, in the case where the weight concentration
rate satisfies [Ni+Co]/Si<4, the electrical conductivity reduces
by solved Si due to too high rate of Si, and further, solderability
deteriorates due to formation of oxide layer of SiO.sub.2 on the
surface of the material during annealing process. The alloy tends
to form coarse Ni--Co--Si particles which do not contribute to
strengthening, and in fact said particles have a tendency to give a
starting point from which cracks are generated during a bending
process and parts where a metal plating cannot be well deposited.
On the other hand, in the case where the rate of Ni and Co to Si is
increased, and [Ni+Co]/Si>5 is satisfied, the electrical
conductivity is dramatically reduced, and therefore, it is not
desirable for an electronic material.
[0022] Therefore, in the present invention, [Ni+Co]/Si ratio in the
alloy composition is controlled so that
4.ltoreq.[Ni+Co]/Si.ltoreq.5 is satisfied.
[0023] The [Ni+Co]/Si ratio preferably satisfies
4.2.ltoreq.[Ni+Co]/Si.ltoreq.4.7.
[0024] It is believed that both of Ni and Co not only contribute to
generation of compound but also associate mutually, so that they
improve the properties of the alloy. It is also possible to further
improve the properties by controlling the weight concentration
ratio of Ni and Co (Ni/Co ratio) in the alloy composition.
Preferably, the Ni/Co ratio should be set within the range
0.5.ltoreq.N/Co.ltoreq.2 in which a remarkable improvement of
strength can be observed. The range 0.8.ltoreq.N/Co.ltoreq.1.3 is
more preferable.
Addition Amount of Cr
[0025] In the Cu--Ni--Si--Co alloy, when the concentrations of Ni,
Si and Co are increased, the total number of precipitated particles
increases, and therefore, higher strength can be achieved by
precipitation strengthening. On the other hand, with the increases
of concentration by addition, the amount of solid solution which
does not contribute to the precipitation also increases, and
therefore the electrical conductivity reduces and though peak
strength of age-precipitation is increased, the electrical
conductivity finally reduces at the peak strength. However, when
0.003-0.3 mass % of Cr, preferably 0.01-0.1 mass % of Cr is added
into said Cu--Ni--Si--Co alloy, the electrical conductivity can be
finally increased without sacrificing strength as compared with
Cu--Ni--Si--Co alloy containing Ni, Si and Co at the same
concentration and further, hot workability is improved, and thus
yield becomes high.
[0026] While the particle which is precipitated when Cr is added
into Cu--Ni--Si--Co alloy tends to be precipitated as particles of
simple substance having bcc structure primarily composed of Cr,
compounds with Si also tend to be precipitated. As for Cr, chromium
silicide (Cr.sub.3Si and the like), which is a compound of Cr with
Si, can be easily precipitated in the copper matrix by an
appropriate heat treatment. Therefore, solid solved Si component
which has not been precipitated as Ni.sub.2Si, CoSi.sub.2 and the
like can be precipitated as Cr--Si compound during the process in
which the properties of alloy are tailored using combination of
solution treatment, cold rolling, and aging treatment. Therefore,
reduction of the electrical conductivity by solid solved Si can be
suppressed, and it is possible to increase the electrical
conductivity without adversely affecting strength.
[0027] In this process, when Si concentration in Cr particle is
low, Si remains in the matrix, and therefore the electrical
conductivity reduces. On the other hand, when the concentration of
Si in the Cr particle is high, Si concentration is reduced which is
required for precipitating Ni--Si particle and Co--Si particle, and
therefore strength is reduced. Further, when Si concentration in Cr
is high, coarse Cr--Si compounds increase and thus bending
workability, fatigue strength and the like are deteriorated.
Further, when the rate of cooling after solution treatment is slow
or aging heat treatment is excessively prolonged, coarse Cr--Si
compound is produced and thus the concentration of Si required for
forming Ni--Si compound reduces. Therefore, Ni--Si compound which
contributes to strengthening becomes insufficient. This occurs due
to the fact that diffusion rates of Si and Cr in Cu are faster than
that of Ni or Co, and thus Cr--Si compound tends to become a coarse
one, and therefore precipitation rate of Cr--Si compound is faster
than that of Ni--Si compound or Co--Si particle.
[0028] Accordingly, when the cooling rate after solution treatment
is controlled and the condition that the temperature and time are
higher and longer than the aging condition which gives the maximum
strength is avoided, the composition, size and density of Cr--Si
compound can be controlled. Therefore, Cr concentration is set at
0.003 mass % or more, and 0.3 mass % or less, and the atomic
concentration ratio of Cr to Si is set at 1-5.
[0029] Further, Cr preferentially precipitates along crystal grain
boundaries in the cooling process at the time of casting. Therefore
the grain boundaries can be strengthened, cracking during hot
working is less liable to occur, and a reduction in yield can be
suppressed. In other words, Cr that has precipitated along the
grain boundaries during casting is solved by solution treatment or
the like, but forms suicide in the subsequent aging precipitation.
With an ordinary Cu--Ni--Si alloy, the portion of the added Si
solved in the matrix, which has not contributed to aging
precipitation, suppresses an increase in electrical conductivity.
However, by adding Cr as a silicide-forming element that causes
silicide to further precipitate, the Si content solved in the
matrix can be reduced as compared with the conventional
Cu--Ni--Si--Co alloy and electrical conductivity can be increased
without compromising strength.
Size and Dispersion Density of Cr--Si Compounds
[0030] Size of Cr--Si compounds affects bending workability,
fatigue strength and the like. In the case where dispersion density
of Cr--Si compounds larger than 5 .mu.m is more than 50/mm.sup.2 or
in the case where dispersion density of Cr--Si compounds the size
of which is 0.1-5 .mu.m is more than 1.times.10.sup.6/mm.sup.2,
bending workability, and fatigue strength remarkably deteriorate.
Further, area number density affects excess and deficiency of Si
concentration in the matrix, and therefore, desired strength
characteristics cannot be obtained in the state where many large
particles are dispersed. Therefore, it is preferable to make the
dispersion density of Cr--Si compounds having the size of over 5
.mu.m not more than 50/mm.sup.2, preferably, not more than
30/mm.sup.2, and more preferably, not more than 10/mm.sup.2. As for
Cr--Si compounds having the size of 0.1-5 .mu.m, dispersion density
should be not more than 1.times.10.sup.6/mm.sup.2, preferably, not
more than 5.times.10.sup.6/mm.sup.2, more preferably, not more than
1.times.10.sup.6/mm.sup.2. Further, when the dispersion density is
1.times.10.sup.4/mm.sup.2 or less, the improvement effect by Cr
addition is small, and therefore it is desired to exceed it. In the
typical embodiment, it is 1.times.10.sup.6/mm.sup.2 or more.
Sn and Zn
[0031] One or more elements selected from Sn and Zn can be added in
a total amount of 0.05-2.0 mass % for improving stress relaxation
characteristics and the like without considerably compromising
strength and electrical conductivity. The addition amount thereof
is preferably 0.05-2.0 mass %, because the effect is insufficient
when it is less than 0.05 mass %, and when it exceeds 2.0 mass %,
manufacturability such as casting properties, electrical
conductivity of the product are compromised.
Other Elements for Addition
[0032] The addition of Mg, Mn, Ag, P, As, Sb, Be, B, Ti, Zr, Al and
Fe exhibits a variety of effects. These elements complement
mutually and improve not only strength and electrical conductivity
but also bending workability, plating characteristic, and
productivities such as hot workability due to the miniaturization
of cast structure. Therefore, one or more elements selected from
them can be optionally added in a total amount of not more than 2.0
mass % into the Cu--Ni--Si--Co--Cr system alloy related to the
present invention according to the properties required. The
addition amount is preferably 0.001-2.0 mass % in total, more
preferably, 0.01-1.0 mass %, because when the total amount of these
elements is less than 0.001 mass %, the desired effect cannot be
obtained, and when it exceeds 2.0 mass %, the electrical
conductivity and manufacturability are remarkably reduced.
[0033] Further, any element which is not described concretely in
the specification of the present application may be added within
the range in which no adverse effect occurs.
[0034] Next, manufacturing method of the present invention is
explained. Cu--Ni--Si--Co--Cr system alloy related to the present
invention can be manufactured by the conventional manufacturing
method, except the condition of solution-treatment and aging
treatment for controlling Ni--Si compound, Co--Si and Cr--Si
compound.
[0035] Firstly, electrolytic cathode copper, Ni, Si, Co, and other
raw materials are melted in an atmospheric melting furnace to
obtain molten metal having the desired composition. The molten
metal is then cast into an ingot. Hot rolling is carried out
thereafter, cold rolling and heat treatment are repeated, and a
strip or a foil having a desired thickness and characteristics are
finished. The heat treatment includes solution treatment and aging
treatment. In the solution treatment, material is heated at a high
temperature of about 700 to about 1000.degree. C., the Ni--Si
compound, Co--Si compound and Cr--Si compound are solved in the Cu
matrix, and the Cu matrix is simultaneously caused to
re-crystallize. Hot rolling sometimes serves as the solution
treatment.
[0036] During the solution treatment, heating temperature and
cooling rate are important. Previously, the cooling rate after
heating was not controlled. Therefore, water cooling using a tank
equipped at the outside of the outlet of a heating furnace, or air
cooling with atmosphere was conducted. In this case, cooling rate
is variable according to the setting of heating temperature, and
therefore, previously, the cooling rate fluctuates in the range of
1.degree. C./sec or less and in the range of 10.degree. C./sec or
more. Accordingly, the control of the alloy as shown in embodiments
of the present invention was difficult.
[0037] It is preferable that the cooling rate is within the range
from 1 to 10.degree. C./sec. In an aging treatment, material is
heated for 1 hour or more, typically 3 to 24 hours in a temperature
range of 350 to 550.degree. C., and Ni--Si compound and Cr--Si
compound are precipitated as microparticles. The aging treatment
results in increased strength and electrical conductivity. Cold
rolling is sometimes performed before and/or after the aging
treatment in order to obtain higher strength. Also, stress relief
annealing (low-temperature annealing) is sometimes performed after
cold rolling in the case where the cold rolling is carried out
after aging.
[0038] In one embodiment, with Cu--Ni--Si--Co--Cr copper alloy
related to the present invention, it is possible that 0.2% yield
strength is 750 MPa or more, and electrical conductivity is 50%
IACS or more, and further it is also possible that 0.2% yield
strength is 800 MPa or more, and electrical conductivity is 50%
IACS or more, and further it is also possible that 0.2% yield
strength is 850 MPa or more, and electrical conductivity is 50%
IACS or more.
[0039] The Cu--Ni--Si--Co--Cr system alloy related to the present
invention can be used to manufacture various wrought copper alloy
products, e.g., plates, strips, tubes, rods, and wires. The
Cu--Ni--Si--Co--Cr system alloy according to the present invention
can be used in lead frame, connectors, pins, terminals, relays,
switches, foil material for secondary batteries, and other
electronic components or the like which are required to satisfy
both high strength and high electrical conductivity (or thermal
conductivity).
EXAMPLES
[0040] Examples of the present invention are described below. The
examples are provided for facilitating understanding of the present
invention and the advantages thereof, and not intended to limit the
scope of the invention.
[0041] Copper alloys used in Examples of the present invention have
the composition in which Sn, Zn, Mg, Mn, Co and Ag are optionally
added into the copper alloy in which several contents of Ni, Si, Co
and Cr are varied as shown in Table 1. Each of copper alloys used
in comparative examples is Cu--Ni--Si--Co--Cr system alloy having a
parameter which is out of range of the present invention.
[0042] Copper alloys having various compositions shown in Table 1
were melted in a high-frequency melting furnace at 1300.degree. C.
and then cast into an ingot having a thickness of 30 mm. Next, the
ingot was heated to 1000.degree. C., hot rolled thereafter to a
plate thickness of 10 mm, and then rapidly cooled. Next, the metal
was faced to a thickness of 8 mm in order to remove scales from the
surface, and sheets having a thickness of 0.2 mm were then formed
by cold rolling. Solution treatment was subsequently carried out by
maintaining the sheets for 120 seconds in Ar gas atmosphere at
800-1000.degree. C. according to the addition amounts of Ni and Cr,
and then cooling them to the room temperature at various cooling
rates. The cooling rate was controlled by varying gas flow rate
blowing against the sample after heating. The cooling rate was
determined by measuring the time required for cooling the sample
from the highest temperature to 400.degree. C. The cooling rate was
5.degree. C./s when the gas was not blown. In a certain embodiment
where the cooling rate was further slower, the cooling rate was
1.degree. C./s when the temperature was reduced with controlling
the heating power. The sheets were then cold rolled to 0.1 mm, and
lastly subjected to the aging treatment in inert atmosphere at
400-550.degree. C. for 1-12 hours according to the addition amount
to manufacture the samples.
[0043] Each alloy thus obtained was evaluated for its strength and
electrical conductivity. As for strength, 0.2% yield strength (YS:
MPa) was measured using a tensile test in the direction paralleling
the rolling. Electrical conductivity (EC; % IACS) was obtained by
measuring volume resistivity using double bridge.
[0044] As for the evaluation of bending workability, 90.degree.
bending processing was performed under the condition in which a
ratio of the thickness of sample sheet to bending radius is 1 using
a W-shaped metal mold. The evaluation was carried out by observing
the surface of the bended portion with an optical microscope, and
the case where crack was not observed is considered to be "good"
since there is practically no problem, and the case where crack was
observed is considered to be "bad". As for fatigue test,
alternating stress was loaded according to JIS Z 2273, and stress
(MPa) with which repeat number until break is 10.sup.7 was
found.
[0045] As for the observation of Cr--Si compound, after
electropolishing, by using FE-AES observation (Nihon-Denshi KK,
JUMP-7800F), particles whose size is 0.1 .mu.m or more were
observed at many positions. Actually, in order to remove the
adsorbed elements (C, O) on the surface, sputtering with Ar.sup.+
was performed, and Auger spectrum of each particle was analyzed.
Detected elements were subjected to sensitivity factor method for
weight-concentration conversion as semi-quantitative value. The
particles in which Cr and Si were detected were chosen for the
evaluation below. "Composition (Cr/Si)", "Size", and "Area
dispersion density" of Cr--Si compound were analyzed by observing
Cr--Si particles whose size is 0.1 .mu.m or more at many positions
with FE-AES and were respectively evaluated as an average
composition, a diameter of the smallest circle, and an average
number in each observation field.
[0046] The results are shown in Table 1 and 2.
TABLE-US-00001 TABLE 1 Solution Cooling Aging Aging Temperature
Rate Temperature Time Ni Si Cr Co Sn Zn Others [Ni + Co]/Si
(.times.120 s) (.degree. C./s) (.degree. C.) (h) Example 1 1.8 0.6
0.005 1.0 4.7 800 4 450 6 2 1.8 0.6 0.05 1.0 4.7 800 4 450 6 3 1.8
0.6 0.1 1.0 4.7 800 4 450 6 4 1.8 0.6 0.1 1.0 0.3 0.5 4.7 800 4 450
6 5 1.8 0.6 0.1 1.0 0.3 0.5 0.1Mg 4.7 800 4 450 6 6 1.8 0.6 0.005
1.0 4.7 900 4 450 6 7 1.8 0.6 0.05 1.0 4.7 900 4 450 6 8 1.8 0.6
0.1 1.0 4.7 900 4 450 6 9 1.8 0.6 0.1 1.0 0.3 0.5 4.7 900 4 450 6
10 1.8 0.6 0.1 1.0 0.3 0.5 0.1Mg 4.7 900 4 450 6 11 1.8 0.6 0.005
1.0 4.7 800 10 450 6 12 1.8 0.6 0.05 1.0 4.7 800 10 450 6 13 1.8
0.6 0.1 1.0 4.7 800 10 450 6 14 1.8 0.6 0.1 1.0 0.3 0.5 4.7 800 10
450 6 15 1.8 0.6 0.1 1.0 0.3 0.5 0.1Mg 4.7 800 10 450 6 16 1.8 0.6
0.005 1.0 4.7 900 10 450 6 17 1.8 0.6 0.05 1.0 4.7 900 10 450 6 18
1.8 0.6 0.1 1.0 4.7 900 10 450 6 19 1.8 0.6 0.1 1.0 0.3 0.5 4.7 900
10 450 6 20 1.8 0.6 0.1 1.0 0.3 0.5 0.1Mg 4.7 900 10 450 6 21 4 1.2
0.2 2.0 5.0 1000 10 450 6 22 1.2 0.6 0.3 1.5 4.5 950 10 450 6 23
2.5 1 0.1 1.5 4.0 950 10 450 6 24 4 1 0.1 0.2 4.2 950 10 450 6 Area
dispersion Area dispersion Density of Density of Cr--Si particles
Cr--Si particles of greater than Composition 0.1-5 micrometers 5
micrometers of Bending (.times.10.sup.6/mm.sup.2) (/mm.sup.2)
Cr--Si particle YS EC Workability Fatigue Example 1 0.26 8 3.1 740
53 Good 270 2 0.40 12 3.1 745 54 Good 280 3 0.87 26 2.9 745 55 Good
275 4 0.87 26 2.9 770 53 Good 280 5 0.87 26 2.9 790 52 Good 280 6
0.22 7 3.0 790 50 Good 285 7 0.34 10 3.0 795 51 Good 290 8 0.75 22
2.8 795 52 Good 295 9 0.75 22 2.8 820 50 Good 300 10 0.75 22 2.8
840 49 Good 305 11 0.20 6 2.7 780 51 Good 270 12 0.32 10 2.7 785 52
Good 280 13 0.70 21 2.5 785 53 Good 280 14 0.70 21 2.5 810 51 Good
280 15 0.70 21 2.5 830 50 Good 305 16 0.18 5 2.6 820 48 Good 300 17
0.28 8 2.6 825 49 Good 305 18 0.60 22 2.4 825 50 Good 305 19 0.60
18 2.4 850 48 Good 310 20 0.60 18 2.4 870 47 Good 315 21 0.96 31
2.8 963 43 Good 330 22 0.87 28 3.2 805 53 Good 290 23 0.91 30 2.4
855 50 Good 310 24 0.67 22 2.4 863 44 Good 310
TABLE-US-00002 TABLE 2 Solution Cooling Aging Aging Temperature
Rate Temperature Time Ni Si Cr Co Sn Zn Others [Ni + Co]/Si
(.times. 120 s) (.degree. C./s) (.degree. C.) (h) Comparative 1 1.8
0.6 0.005 3.0 800 4 450 6 Examples 2 1.8 0.6 0.05 3.0 800 4 450 6 3
1.8 0.6 0.1 3.0 800 4 450 6 4 1.8 0.6 0.1 0.3 0.5 3.0 800 4 450 6 5
1.8 0.6 0.1 0.3 0.5 0.1Mg 3.0 800 4 450 6 6 1.8 0.6 0.005 3.0 800
10 450 6 7 1.8 0.6 0.05 3.0 800 10 450 6 8 1.8 0.6 0.1 3.0 800 10
450 6 9 1.8 0.6 0.1 0.3 0.5 3.0 800 10 450 6 10 1.8 0.6 0.1 0.3 0.5
0.1Mg 3.0 800 10 450 6 11 1.8 0.6 -- 3.0 800 4 450 6 12 1.8 0.6 --
1.0 4.7 900 4 450 6 13 1.8 0.6 0.05 1.0 4.7 900 0.5 450 6 14 1.8
0.6 0.1 1.0 4.7 900 0.5 450 6 15 1.8 0.6 0.05 1.0 4.7 900 15 450 6
16 1.8 0.6 0.1 1.0 4.7 900 15 450 6 17 1.8 0.6 0.1 1.0 4.7 900 10
600 6 18 1.8 0.6 0.1 1.0 4.7 900 10 600 6 19 1.8 0.6 0.5 1.0 4.7
900 10 450 6 20 1.8 0.6 0.5 1.0 4.7 900 4 450 6 Area dispersion
Area dispersion Density of Density of Cr--Si particles Cr--Si
particles of greater than Composition 0.1-5 micrometers 5
micrometers of Bending (.times. 10.sup.6/mm.sup.2) (/mm.sup.2)
Cr--Si particle YS EC Workability Fatigue Comparative 1 0.10 3 3.3
730 47 Good 265 Examples 2 0.13 4 3.3 735 48 Good 270 3 0.17 5 3.1
735 49 Good 270 4 0.17 5 3.1 750 47 Good 275 5 0.17 5 3.1 770 46
Good 280 6 0.08 2 2.8 760 44 Good 270 7 0.10 3 2.8 765 45 Good 265
8 0.14 4 2.7 765 46 Good 265 9 0.14 4 2.7 780 44 Good 270 10 0.14 4
2.7 800 43 Good 275 11 -- -- -- 730 43 Good 290 12 -- -- -- 785 45
Good 290 13 13 55 3.0 705 55 Bad 205 14 17 72 2.8 715 54 Bad 210 15
0.03 0 23.0 770 46 Good 275 16 0.09 0 26.0 780 45 Good 280 17 16 66
6.0 685 57 Bad 245 18 20 87 7.0 695 56 Bad 250 19 11 47 3.1 765 46
Bad 275 20 15 64 3.1 735 52 Bad 260
[0047] In Examples 1-24 of the present invention, as a suitable
range of cooling rate was employed, and therefore area dispersion
density of Cr--Si compound is 1.times.10.sup.6 or less, and Cr/Si
is 1-5, and therefore, excellent properties were obtained.
[0048] On the other hand, Co was not included in Comparative
Examples 1-10, and Cr was not included in Comparative Examples 11
and 12, and therefore, the strength and electrical conductivity
could not be achieved at high level. In Comparative Examples 13 and
14, sufficient strength was not obtained because Cr--Si was
overgrown due to too slow coding rate, and further, bending
workability was also poor.
[0049] In Comparative Examples 15 and 16, strength and electrical
conductivity were deteriorated because excessive Si remained in the
alloy since Cr--Si compound did not grow due to fast cooling rate.
In Comparative Examples 17 and 18, sufficient strength could not be
obtained because Cr--Si compound was overgrown since aging
temperature was high, and bending workability was also poor.
Further, Cu, Ni and the like diffused into the coarse particles,
and thus Si concentration decreased in the particles, and therefore
Cr/Si rate relatively increased. In Comparative Examples 19 and 20,
as Cr concentration was too high, Cr--Si compound was overgrown,
and therefore sufficient strength could not be obtained and bending
workability was also poor.
* * * * *