U.S. patent application number 10/341895 was filed with the patent office on 2003-08-21 for high-strength and high-conductivity cu-(ni, co, fe)-si copper alloy for use in leadframes.
This patent application is currently assigned to INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE. Invention is credited to Jean, Ren-Der, Lee, I-Ching, Liu, Jin-Yaw, Liu, Ray-Iun, Sha, Yu-Lian, Teng, Mao-Ying.
Application Number | 20030155050 10/341895 |
Document ID | / |
Family ID | 27735068 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030155050 |
Kind Code |
A1 |
Liu, Jin-Yaw ; et
al. |
August 21, 2003 |
High-strength and high-conductivity Cu-(Ni, Co, Fe)-Si copper alloy
for use in leadframes
Abstract
A high-strength and high-conductivity copper alloy is disclosed
which contains essentially of: (a) from 0.5 to 2.5 wt % of Ni; (b)
from 0.5 to 2.5 wt % of Co; (c) from 0.5 to 0.8 wt % of Si; (d).
from 0.05 to 0.15 wt % of either Mg or P or both; and (e) the
balance of Cu. The amounts of Co, Ni, and Si satisfy the following
equations: 2%.ltoreq.(Ni+Co).ltoreq.- 4%, and
0.8.ltoreq.(Ni/4+Co/6)/Si.ltoreq.1.2. The new copper alloy exhibits
substantially improved electrical conductivity, greater than 65%
IACA, than the commercially available C7025 copper alloy, while
maintaining a satisfactory tensile strength (greater than 600 MPa),
and, thus, can be most advantageously used for preparing leadframes
for use in high pin-number (greater than 100 pins) IC
application.
Inventors: |
Liu, Jin-Yaw; (Hsinchu,
TW) ; Sha, Yu-Lian; (Yeong-Ho City, TW) ; Lee,
I-Ching; (Hua-Lien City, TW) ; Teng, Mao-Ying;
(Hsinchu, TW) ; Liu, Ray-Iun; (Hsinchu, TW)
; Jean, Ren-Der; (Hsinchu, TW) |
Correspondence
Address: |
LAW OFFICE OF LIAUH & ASSOC.
4224 WAIALAE AVE
STE 5-388
HONOLULU
HI
96816
|
Assignee: |
INDUSTRIAL TECHNOLOGY RESEARCH
INSTITUTE
Hsinchu Hsien
TW
|
Family ID: |
27735068 |
Appl. No.: |
10/341895 |
Filed: |
April 21, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10341895 |
Apr 21, 2003 |
|
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09961481 |
Sep 21, 2001 |
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6506269 |
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Current U.S.
Class: |
148/554 ;
420/485 |
Current CPC
Class: |
C22F 1/08 20130101; C22C
9/06 20130101 |
Class at
Publication: |
148/554 ;
420/485 |
International
Class: |
C22F 001/08; C22C
009/06 |
Claims
What is claimed is:
1. A copper alloy consisting essentially of: (a) from 0.5 to 2.5 wt
% of Ni; (b) from 0.5 to 2.5 wt % of Co; (c) from 0.5 to 0.8 wt %
of Si; (d) from 0.05 to 0.15 wt % of either Mg or P or both; and
(e) the balance of Cu; (f) wherein the amounts of Co, Ni, and Si
satisfy the following equations: 2%.ltoreq.(N+Co).ltoreq.4%, and
0.8.ltoreq.(Ni/4+Co/6)/Si.ltor- eq.1.2.
2. The copper alloy according to claim 1 which consists essentially
of: from 0.5 to 2.5 wt % of Ni, from 0.5 to 2.5 wt % of Co, from
0.4 to 0.8 wt % of Si, from 0.05 to 0.15 wt % of (Mg and/or P), and
the balance of Cu, wherein the sum of Ni and Co is between 2.0 and
4.0 wt %.
3. The copper alloy according to claim 1 which is formed from a
process comprising the following steps: (a) melting constituting
metals using a high frequency induction furnace followed by rapid
cooling to form ingots of desired sizes; (b) homogenizing said
ingots at about 800 to 950.degree. C. for about 1/2 to 5 hours; (c)
hot working said homogenized ingots to form copper alloy plate at a
hot reduction ratio of 70% or greater in thickness, followed by
water quenching and then milled to remove oxide and scales; (d)
cold rolling said copper alloy plate to a thickness reduction of
50% or greater, followed by annealing at about 800 to 950.degree.
C. for 30 seconds to 30 minutes then rapidly cooling said copper
alloy plate; (e) cold rolling said copper alloy plate to a
thickness reduction of 50% or greater; and (f) aging said copper
alloy plates at about 300 to 600.degree. C. for 30 minutes to 5
hours.
4. The copper alloy according to claim 3 wherein said process for
making said copper alloy further comprises the step of subjecting
said copper alloy plate to additional cold rolling after aging.
5. The copper alloy according to claim 1 wherein said process for
making said copper alloy further comprising the following steps:
(a) melting constituting metals using a high frequency induction
furnace followed by rapid cooling to form ingots of desired sizes;
(b) homogenizing said ingots at about 800 to 950.degree. C. for
about 1/2 to 5 hours; (c) hot working said homogenized ingots to
form copper alloy plates at a reduction ratio of 70% or greater in
thickness, followed by water quenching and then milled to remove
oxide and scales; (d) cold rolling said copper alloy plates to a
cold reduction of 50% or greater; and (e) aging said copper alloy
plates at about 300 to 600.degree. C.
6. The copper alloy according to claim 5 wherein said process for
making said copper alloy further comprises the step of subjecting
said copper alloy plate to additional cold rolling after aging.
7. The copper alloy according to claim 1 which has a tensile
strength of at least 600 MPa and an electrical conductivity of at
least 65% IACS.
8. A process for preparing copper alloy comprising the following
steps: (a) preparing a metal mixture consisting essentially of (i)
from 0.5 to 2.5 wt % of Ni; (ii) from 0.5 to 2.5 wt % of Co; (iii)
from 0.5 to 0.8 wt % of Si; (iv) from 0.05 to 0.15 wt % of either
Mg or P or both; and (v) the balance of Cu; (vi) wherein the
amounts of Co, Ni, and Si satisfy the following equation:
2%.ltoreq.(Ni+Co).ltoreq.4%, and
0.8.ltoreq.(Ni/4+Co/6)/Si.ltoreq.1.2. (b) melting constituting
metals using a high frequency induction furnace followed by rapid
cooling to form ingots of desired sizes; (c) homogenizing said
ingots at about 800 to 950.degree. C. for about 1/2 to 5 hours; (d)
hot working said homogenized ingots to form copper alloy plate at a
hot reduction ratio of 70% or greater in thickness, followed by
water quenching and then milled to remove oxide and scales; (e)
cold rolling said copper alloy plate to a thickness reduction of
50% or greater, followed by annealing at about 800 to 950.degree.
C. for 30 seconds to 30 minutes then rapidly cooling said copper
alloy plate; (f) cold rolling said copper alloy plate to a
thickness reduction of 50% or greater; and (g) aging said copper
alloy plates at about 300 to 600.degree. C. for 30 minutes to 5
hours.
9. The process for preparing copper alloy according to claim 8
wherein said metal mixture consists essentially of: from 0.5 to 2.5
wt % of Ni, from 0.5 to 2.5 wt % of Co, from 0.4 to 0.8 wt % of Si,
from 0.05 to 0.15 wt % of (Mg and/or P), and the balance of Cu,
wherein the sum of Ni and Co is between 2.0 and 4.0 wt %.
10. process for preparing copper alloy according to claim 8 which
further comprises the step of subjecting said copper alloy plate to
additional cold rolling after aging.
11. A process for preparing copper alloy comprising the following
steps: (a) preparing a metal mixture consisting essentially of: (i)
from 0.5 to 2.5 wt % of Ni; (ii) from 0.5 to 2.5 wt % of Co; (iii)
from 0.5 to 0.8 wt % of Si; (iv) from 0.05 to 0. 15 wt % of either
Mg or P or both; and (v) the balance of Cu; (vi) wherein the
amounts of Co, Ni, and Si satisfy the following equations:
2%.ltoreq.(Ni+Co).ltoreq.4%, and
0.8.ltoreq.(Ni/4+Co/6)/Si.ltoreq.1.2. (b) melting constituting
metals using a high frequency induction furnace followed by rapid
cooling to form ingots of desired sizes; (c) homogenizing said
ingots at about 800 to 950.degree. C. for about 1/2 to 5 hours; (d)
hot working said homogenized ingots to form copper alloy plates at
a reduction ratio of 70% or greater in thickness, followed by water
quenching and then milled to remove oxide and scales; (e) cold
rolling said copper alloy plates to a cold reduction of 50% or
greater; and (f) aging said copper alloy plates at about 300 to
600.degree. C.
12. The process for preparing copper alloy according to claim 11
wherein said metal mixture consists essentially of: from 0.5 to 2.5
wt % of Ni, from 0.5 to 2.5 wt % of Co, from 0.4 to 0.8 wt % of Si,
from 0.05 to 0.15 wt % of (Mg and/or P), and the balance of Cu,
wherein the sum of Ni and Co is between 2.0 and 4.0 wt %.
13. The process for preparing copper alloy according to claim 11
which further comprises the step of subjecting said copper alloy
plate to additional cold rolling after aging.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an improved copper alloy
for use in the integrated-circuit (IC) industry. More specifically,
the present invention relates to an improved copper alloy which
exhibits high strength as well as high conductivity so that it can
be most advantageously utilized in many task specific applications
such as making leadframes and other thin conducting components for
high pin-number IC applications.
BACKGROUND OF THE INVENTION
[0002] Copper alloys are one of the most important and ubiquitous
elements in the fabrication of integrated-circuits (IC). With the
rapid development of the computer and communication technology, the
IC industry is experiencing an unprecedented expansion. This leads
to increased demand on the quantity and quality of IC packaging
technology. One of the key elements in the IC packaging technology
is to develop improved leadframes to provide high quality
electrical communication into and out of the semiconductor devices
contained in the IC chip.
[0003] Leadframes are bridges that provide communications for
electrical signals among different parts of an IC board. In
addition to transporting electrical signals, leadframes also
provide an important function allow efficient dissipation of heat
that will be generated during the busy flow of electrons. As the
trend in the IC industry is to become more highly integrated, the
lines become finer, the frequency gets higher, and the cost
continues to be lowered, many associated changes are also taking
place. For example, plastics has taken the place of ceramics and
the leadframe materials are changed from Fe--Ni alloys to copper
alloys.
[0004] A number of copper alloys have been developed for
fabricating leadframes and various other applications. At the
present time, there are at least sixty different commercially
available copper alloys for making leadframes. Generally speaking,
the copper alloys can be divided into three categories: (1) high
conductivity, typically with a conductivity greater than 80% IACS,
but with a tensile strength lower than 400 MPa; (2) medium-to-high
conductivity and medium strength, typically with a conductivity
greater than 50% IACS and a tensile strength between 400 and 500
MPa; and (3) high strength, typically for use in making leadframes
for IC's with 100 or more pins. The third type copper alloys
typically have a tensile strength greater than 600 MPa but
electrical conductivity of 35% IACS or higher.
[0005] The first type is commonly used in making leadframes for use
in transistors. Examples of the first type copper alloys include C
19210 (KFK, TAMAC4), C 15100 (HCL-151, Mitsubishi C151, ZC2, etc.),
C18030 (EFTEC6), etc. Examples of the second type include C19400
(Olin C194, TAMAC194, HCL194, KLF194), C18040 (EFTEC64), C19500,
C19600, TAMAC5, EFTEC5, etc.; the constitute the bulk of copper
alloys for making leadframes for ICs. And examples of the third
type include C7025 and KLF125. Several patents discussed the C7025
alloys, these include: U.S. Pat. Nos. 4,594,221, and 4,729,372, and
Taiwan Patent No. 120,435.
[0006] The following U.S. patents provide some background
information on copper alloys.
[0007] U.S. Pat. No. 4,950,451 discloses and claims a copper alloy
for an electronic device consisting essentially of 1.0 wt %-4.0 wt
% of Ni, more than 0.2 wt % and less than 0.8 wt % of P, 0.5 wt
%-6.0 wt % of Zn, 0.05 wt %-1.0 wt % of Mg, and the rest being
copper and unavoidable impurties.
[0008] U.S. Pat. No. 5,064,611 discloses an claims a method for
producing a copper alloy, which comprises steps of: quenching to
solidify, at a cooling rate in the range from 100.degree. C./sec to
100,000.degree. C./sec, a molten metal consisting essentially of
1.0 to 8 wt % of Ni, 0.1 to 0.8 wt % of P, 0.06 to 1.0 wt % of Si,
and a remainder of Cu and unavoidable impurities; and continuously
cooling in succession said solidified metal to normal temperature
to cause an inteirmetallic compound of Ni--P and Ni--Si to be
finely and uniformed into the matrix material.
[0009] U.S. Pat. No. 5,215,711 discloses and claims an
age-hardening copper alloy consisting of: (1) copper; (2) 1-2.5 wt
% of Ni; (3) from more than 0.01 wt % to less than 7 wt % of Si;
(4) from more than 0.01 wt % to less than 10 wt % of Fe; (5) from
more than 0.01 wt % to less than 7 wt % of Ti; and (6) from more
than 0.001 wt % to less than 1 wt % of B; wherein the amount of
copper constitutes the balance of the weight of the alloy.
[0010] U.S. Pat. No. 5,248,351 discloses and claims a copper alloy
for an electronic device which consists essentially of 2.0 wt %-8
wt % of Ni, 0.1 wt %-0.8 wt % of P, 0.06-I wt % of Si, and the rest
being Cu and unavoidable impurties, wherein the weight of Ni, P+Si
is within the range fo from 4.12:1 to 6.06:1; and wherein
Ni.sub.5P.sub.2nd Ni.sub.2Si intermetallic compounds are
present.
[0011] U.S. Pat. No. 5,250,256 discloses and claims a high-tensile
copper alloy for current conduction consisting essentially of: (1)
from 2.0 wt % to 4.0 wt % of Ni; (2) from 0.4 wt % to 1.0 wt % of
Si; (3) 0.05 wt % to 0.3 wt % of In; (4) from 0.01 wt % to 0.2 w t%
of Co; and (5) the balance of Cu.
[0012] U.S. Pat. No. 5,334,346 discloses and claims a copper alloy
having high strength, enhanced ductility, and good electrical
conductivity consisting essentially of (1) from about 0.5 wt % to
2.4 wt % nickel; (2) from 0.1 wt % to 0.5 wt % silicon; (3) from
0.02 wt % to 0.16 wt % phosphorus; (4) from 0.02 wt % to 0.2 wt %
magnesium; and (5) the balance copper.
[0013] A number ofJapanese patents also discussed copper alloys.
These include JP-7-18356, JP-4-356284, JP-7-18355, JP-2522629,
JP-2705875, JP-6-299275, JP-6-172895, JP-5-331574, JP-6-128708,
JP-8-503022, JP-7-62504.
[0014] As discussed earlier, C7025 alloy provides medium
conductivity as well as high strength. A typical C7025 alloy, as
disclosed in Taiwan Pat. No.120435, can exhibit the same kind of
strength as Fe-42 Ni alloy, however, its electrical conductivity is
more than 10 times better than the 42 alloy. However, its
electrical conductivity can only reach 35 to 50% IACS at the
maximum Because of the significance of leadframes and other
electric current conducting devices in the IC industry, both
commercially and technologically speaking, it is important to
continue the development of other types of copper alloys which can
further improve the performance and lower the cost of electronic
devices.
SUMMARY OF THE INVENTION
[0015] The primary object of the present invention is to develop an
improved copper alloy for use in preparing IC devices. More
specifically, the primary object of the present invention is to
develop an improved copper alloy with both improved strength and
improved conductivity, so as to satisfy today's need for
high-conductivity and high-strength leadframes which have become a
critical element in today's IC packaging applications.
[0016] The copper alloy disclosed in the present invention consists
essentially of Ni, Co, Si, (Mg and/or P), and Cu. The amount of Ni
is from 0.5 to 2.5 wt %, the amounts of Co, Ni, and Si satisfy the
following equation: 0.8.ltoreq.(Ni/4+Co/6)/Si.ltoreq.1.2, the
amount of (Mg and/or P) is from 0.05 to 0.15 wt %, with the balance
being Cu. Furthermore, it is preferred that
2%.ltoreq.Ni+Co.ltoreq.4%. The copper alloy of the present
invention is classified, similar to C7025 alloy, as belonging to
the third type copper alloy with high electrical conductivity and
high strength. However, the copper alloy of the present invention
exhibits unexpected superior results in that its electrical
conductivity exceeds the values of 35 to 50% IACS provided by
C7025, while providing the same or even better tensile
strength.
[0017] In the preferred embodiment of the present invention, the
copper alloy consists essentially from 0.5 to 2.5 wt % of Ni, from
0.5 to 2.5 wt % of Co, from 0.4 to 0.8 wt % of Si, from 0.05 to
0.15 wt % of (Mg and/or P), and the balance of Cu, wherein the sum
of Ni and Co is between 2.0 and 4.0 wt %.
[0018] There are two alternative approaches to fabricate the copper
alloy plates or strips of the present invention: a high-temperature
approach and a cold-temperature.
[0019] With the high-temperature approach, copper alloys having
appropriate compositions are melt using a high frequency induction
furnace and then cast by rapid cooling to form ingots of desired
sizes. The hot ingots are homogenized at 800 to 950.degree. C. for
about 1/2 to 5 hours, then are immediately subjected to hot working
to a rate of 70% or greater (i.e., its thickness is reduced by 70%
or greater), followed by water quenching and then milled to remove
oxide and scales. The alloy plates so obtained are subject to cold
rolling (cold working) to a thickness reduction of 50% or greater,
followed by annealing at 800 to 950.degree. C. for 30 seconds to 30
minutes, then they are rapidly cooled. Thereafter, the alloy plates
are cold rolled again to 50% or above. The steps of annealing and
cold rolling can be repeated if necessary. After the cold rolling,
the alloy plates are subjected to heat aging treatment at 300 to
600.degree. C. for 30 minutes to 5 hours, to obtain the desired
strength and current conductivity. If necessary, the aged copper
alloy strips can be further subject to a small amount of cold
working; however, the amount of the additional cold working should
be less than 40%.
[0020] With the low-temperature approach, copper alloys having
appropriate compositions are melt using a radio frequency oven and
then cast by rapid cooling to form ingots of desired sizes. The hot
ingots are homogenized at 800 to 950.degree. C. for about 1/2 to 5
hours, then are immediately subjected to hot working to a reduction
ratio of at least 70% in thickness, followed by water quenching and
then milled to remove oxide and scales. Thereafter, the copper
plates are cold rolled a cold reduction ratio of 50% of greater in
thickness, followed by aging at 300 to 600.degree. C. The steps of
cold working and aging may be repeated so as to obtain the desired
strength and current conductivity. If necessary, the aged copper
alloy strips can be further subject to a small amount of cold
working; however, the amount of the additional cold working should
be less than 40%.
[0021] The copper alloys prepared from either process exhibits
excellent electrical conductivity and tensile strength, and thus,
can be advantageously used for the fabrication of leadframes for
use in semiconductor industries.
BRIEF DESCRIPTION OF THE DRAWING
[0022] The present invention will be described in detail with
reference to the drawing show preferred embodiment of the present
invention, wherein:
[0023] FIG. 1A is schematic flowchart diagram showing the main
steps according to the high-temperature approach of the present
invention.
[0024] FIG. 1B is schematic flowchart diagram showing the main
steps according to the low-temperature approach of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0025] The present invention discloses an improved copper alloy
which exhibits excellent tensile strength as well as current
conductivity thus can be advantageously used for fabricating
leadframes which have become a critical element in today's IC
packaging applications. Unexpected results were observed when the
copper alloy was prepared according to a specific formulation. The
tensile strength of the new copper alloy of the present invention
compares favorably relative to that of C7025, a type III copper
alloy, while it provides substantially improved electrical
conductivity.
[0026] The copper alloy disclosed in the present invention consists
essentially of:
[0027] (a) from 0.5 to 2.5 wt % Ni;
[0028] (b) from 0.5 to 2.5 wt % Co;
[0029] (c) from 0.5 to 0.8 wt % Si;
[0030] (d) from 0.05 to 0.15 wt % of either Mg or P or both;
and
[0031] (e) the balance Cu;
[0032] (f) wherein the amounts of Co, Ni, and Si satisfy the
following equations:
2%.ltoreq.(Ni+Co).ltoreq.4%, and
0.8.ltoreq.(Ni/4+Co/6)/Si.ltoreq.1.2.
[0033] In the preferred embodiment of the present invention, which
is designated as the Cu--Ni--Co series, the copper alloy consists
essentially from 0.5 to 2.5 wt % of Ni, from 0.5 to 2.5 wt % of Co,
from 0.4 to 0.8 wt % of Si, from 0.05 to 0.15 wt % of (Mg and/or
P), and the balance of Cu, wherein the sum of Ni and Co is between
2.0 and 4.0 wt %.
[0034] Depending on the type of applications, the copper alloys of
the present invention can be fabricated using either a
high-temperature approach or a cold-temperature approach. With the
high-temperature approach, copper alloys having appropriate
compositions are melt using a high frequency induction furnace and
then cast by rapid cooling to form ingots of desired sizes. The hot
ingots are homogenized at 800 to 950.degree. C. for about 1/2 to 5
hours, then are immediately subjected to hot working to a rate of
70% or greater (i.e., its thickness is reduced by 70% or greater),
followed by water quenching and then milled to remove oxide and
scales. The alloy plates so obtained are subject to cold rolling
(cold working) to a thickness reduction of 50% or greater, followed
by annealing at 800 to 950.degree. C. for 30 seconds to 30 minutes,
then they are rapidly cooled. Thereafter, the alloy plates are cold
rolled again to 50% or above. The steps of annealing and cold
rolling can be repeated if necessary. After the cold rolling, the
alloy plates are subjected to heat aging treatment at 300 to
600.degree. C. for 30 minutes to 5 hours, to obtain the desired
strength and current conductivity. If necessary, the aged copper
alloy strips can be further subject to a small amount of cold
working; however, the amount of the additional cold working should
be less than 40%.
[0035] With the low-temperature approach, copper alloys having
appropriate compositions are first similarly melt using a radio
frequency oven and then cast by rapid cooling to form ingots of
desired sizes. The hot ingots are homogenized at 800 to 950.degree.
C. for about 1/2 to 6 hours, then are immediately subjected to hot
working to a rate of at least 70%, followed by cold working (i.e.,
cold rolling) to achieve a cold reduction of at least 40%, and then
precipitate hardening and again at 300 to 600.degree. C. The steps
of cold working and aging may be repeated so as to obtain the
desired strength and current conductivity. If necessary, the aged
copper alloy strips can be further subject to a small amount of
cold working; however, the amount of the additional cold working
should be less than 40%.
[0036] The present invention will now be described more
specifically with reference to the following examples. It is to be
noted that the following descriptions of examples, including the
preferred embodiment of this invention, are presented herein for
purposes of illustration and description, and are not intended to
be exhaustive or to limit the invention to the precise form
disclosed.
EXAMPLES 1-6
Cu--Ni--Co Series Copper Alloys
[0037] Copper alloys containing the compositions described in Table
IA were prepared using both the high-temperature approach (I) and
the low-temperature approach (II). The amounts of individual atoms
are expressed in weight percent (wt %).
1 TABLE 1A Cu Ni Co Si Mg P Example 1 Bal. 1.86 0.66 0.56 0.09 --
Example 2 Bal. 0.99 1.16 0.55 -- 0.096 Example 3 Bal. 1.99 0.99
0.62 -- 0.11 Example 4 Bal. 1.49 1.46 0.58 -- 0.10 Example 5 Bal.
0.60 2.37 0.62 -- 0.099 Example 6 Bal. 0.98 1.48 0.52 -- 0.096
[0038] The copper alloy plates so obtained were tested for their
hardness, current conductivity, tensile strength, elongation. The
test results are reported for the copper alloys before and after
the additional 10% cold working, in Tables 1B and 1C, respectively;
in both cases the copper alloys had been subject to aging heat
treatment.
2 TABLE 1B Tensile Hardness Conductivity Strength Elongation (Hv)
(% IACS) (MPa) (%) Process I II I II I II I II Example 1 212 257
46.8 51.5 708 851 8.80 4.45 Example 2 190 210 46.3 53.7 604 677
9.07 4.24 Example 3 216 204 47.2 63.2 641 635 7.16 7.035 Example 4
201 200 48.1 68.7 629 624 8.44 6.465 Example 5 179 202 54.9 63.8
589 668 6.26 5.994 Example 6 187 211 51.0 58.6 614 669 11.1
7.54
[0039]
3 TABLE 1 C Tensile Hardness Conductivity Strength Elongation (Hv)
(% IACS) (MPa) (%) Process I II I II I II I II Example 1 211 233
51.9 5303 709 905 10.81 3.07 Example 2 193 212 46.5 49.7 623 727
8.32 3.49 Example 3 209 203 48.4 56.5 704 705 7.16 4.00 Example 4
197 194 49.2 65.3 682 705 5.69 4.41 Example 5 181 209 52.5 66.5 600
651 6.73 3.25 Example 6 183 205 50.8 55.4 623 730 6.125 4.11
[0040] For comparable commercial products, such as C7025 and
KLF125, the hardness, conductivity, tensile Strength, and
elongation would be 190-200 Hv, 35-50 % IACS, 600-660 Mpa, and 6%
elongation, respectively. Thus, the copper alloys of the present
invention clearly exhibit superior conductivity and tensile
strength than those of commercial products.
COMPARATIVE EXAMPLE
[0041] The copper alloy plate was prepared from C7025 alloy, a
commercially available copper alloy commonly used in the
fabrication of high pin-number ICs. The copper alloy plate was for
its hardness, current conductivity, tensile strength, elongation.
The composition of the C7025 alloy is listed in Table 2A, and the
test results are reported in Table 2B. The specimens of the test
materials shown in Table 2B were cold rolled 30% after the final
aging treatment.
4 TABLE 2A Cu Ni Co Fe Si Mg P Comp. Exam. Bal. 3.03 -- -- 0.71
0.17 --
[0042]
5 TABLE 2B Tensile Hardness Conductivity Strength Elongation (Hv)
(% IACS) (MPa) (%) Process I II I II I II I II Comp. Exam. -- --
46.1 38.7 696 970 2 2
[0043] The above results show that the copper alloy of the present
invention provides substantially higher conductivity (better than
45% IACS) than the commercially available type 3 copper alloy,
while maintaining satisfactory tensile strength (greater than 600
MPa) for high-pin-number ICs.
[0044] The foregoing description of the preferred embodiments of
this invention has been presented for purposes of illustration and
description. Obvious modifications or variations are possible in
light of the above teaching. The embodiments were chosen and
described to provide the best illustration of the principles of
this invention and its practical application to thereby enable
those skilled in the art to utilize the invention in various
embodiments and with various modifications as are suited to the
particular use contemplated. All such modifications and variations
are within the scope of the present invention as determined by the
appended claims when interpreted in accordance with the breadth to
which they are fairly, legally, and equitably entitled.
* * * * *