U.S. patent application number 11/902238 was filed with the patent office on 2008-06-12 for method for manufacturing copper nanoparticles and copper nanoparticles manufactured using the same.
This patent application is currently assigned to SAMSUNG ELECTRO-MECHANICS CO., LTD.. Invention is credited to Jae-Woo Joung, Byung-Ho Jun, Kwi-Jong Lee, Young-Il Lee.
Application Number | 20080138643 11/902238 |
Document ID | / |
Family ID | 39296408 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080138643 |
Kind Code |
A1 |
Lee; Kwi-Jong ; et
al. |
June 12, 2008 |
Method for manufacturing copper nanoparticles and copper
nanoparticles manufactured using the same
Abstract
The present invention relates to a method for manufacturing
copper nanoparticles and copper nanoparticles thus manufactured, in
particular, to a method for manufacturing copper nanoparticles,
wherein the method includes producing mixture by mixing one or more
copper salt selected from a group consisting of CuCl.sub.2,
Cu(NO.sub.3).sub.2, CuSO.sub.4, (CH.sub.3COO).sub.2Cu and
Cu(acac).sub.2 (copper acetyloacetate) with fatty acid and
dissociating; and reacting the mixture by heating and copper
nanoparticle. According to the present invention, copper
nanoparticles can be synthesized in a uniform size and a high
concentration using general copper salt as a copper precursor
material in non-aqueous system without designing precursor
material. The present invention is not only environment-friendly,
but also economical as highly expensive equipment is not
demanded.
Inventors: |
Lee; Kwi-Jong; (Suwon-si,
KR) ; Joung; Jae-Woo; (Suwon-si, KR) ; Lee;
Young-Il; (Anyang-si, KR) ; Jun; Byung-Ho;
(Seoul, KR) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
SAMSUNG ELECTRO-MECHANICS CO.,
LTD.
|
Family ID: |
39296408 |
Appl. No.: |
11/902238 |
Filed: |
September 20, 2007 |
Current U.S.
Class: |
428/570 ;
75/343 |
Current CPC
Class: |
Y10T 428/12181 20150115;
B22F 1/0018 20130101; B22F 9/30 20130101; B22F 9/24 20130101; B82Y
30/00 20130101 |
Class at
Publication: |
428/570 ;
75/343 |
International
Class: |
B22F 1/02 20060101
B22F001/02; B22F 9/16 20060101 B22F009/16 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 10, 2006 |
KR |
10-2006-0098315 |
Claims
1. A method for manufacturing copper nanoparticles, the method
comprising: producing a mixture by dissociating one or more copper
salt selected from a group consisting of CuCl.sub.2,
Cu(NO.sub.3).sub.2, CuSO.sub.4, (CH.sub.3COO).sub.2Cu and
Cu(acac).sub.2 (copper acetyloacetate) into fatty acid; and
reacting the mixture by heating.
2. The method of claim 1, wherein the fatty acid is selected from a
group consisting of saturated fatty acids (C.sub.nH.sub.2nO.sub.2),
oleic acids (C.sub.nH.sub.2n-2O.sub.2), lynolic acid
(C.sub.nH.sub.2n-4O.sub.2), lynolene acids
(C.sub.nH.sub.2n-6O.sub.2) and high unsaturated acids
(C.sub.nH.sub.2n-3O.sub.2, C.sub.nH.sub.2n-10O.sub.2,
C.sub.nH.sub.2n-12O.sub.2) (n is an integer of 10-18).
3. The method of claim 2, wherein the fatty acid is one or more
selected from a group consisting of dodecarnoic acid
(C.sub.11H.sub.23COOH), oleic acid (C.sub.17H.sub.33COOH),
hexadecanoic acid (C.sub.15H.sub.33COOH) and tetradecanoic acid
(C.sub.13H.sub.27COOH).
4. The method of claim 1, wherein the fatty acid is mixed in a mole
ratio of 2 to 10 with respect to the copper salt.
5. The method of claim 1, wherein a primary aliphatic amine having
carbon numbers of 3 to 18 is further added to the mixture.
6. The method of claim 5, wherein the primary aliphatic amine is
oleylamine or butylamine.
7. The method of claim 5, wherein the primary aliphatic amine is
further added in a mole ratio of 1 to 10 with respect to copper
salt.
8. The method of claim 1, one or more nonpolar solvents selected
from a group consisting of toluene, xylene, chloroform,
dichloromethane, hexane, tetradecane and octadecene is further
added to the mixture.
9. The method of claim 8, the nonpolar solvent is added in 200 to
1000 parts by weight with respect to 100 parts by weight of the
copper salt.
10. The method of claim 1, the heating temperature is 50 to
300.degree. C.
11. The method of claim 1, the heating temperature is 150 to
300.degree. C.
12. The method of claim 1, further comprises: after reacting the
mixture, adding at least one reducing agent selected from group
consisting of NaBH.sub.4, LiBH.sub.4, KBH.sub.4, tetrabutylammonium
borohydride, N.sub.2H.sub.4, PhHNNH.sub.2, NH.sub.3--BH.sub.3,
(CH.sub.3).sub.3N--BH.sub.3, formate and NaHPO.sub.2 into the
mixture; and reacting the mixture by heating.
13. The method of claim 12, prior to adding the reducing agent, the
heating temperature of the mixture is 50 to 110.degree. C.
14. The method of claim 12, the reducing agent is added in a mole
ratio of 1 to 6 with respect to the copper salt.
15. The method of claim 12, the heating temperature is 50 to
150.degree. C.
16. The method of claim 1, the cooper nanoparticles has a size of 5
to 40 nm.
17. Copper nanoparticles manufactured by a method of claim 1,
wherein surface of the copper nanoparticles comprises fatty acid as
a capping molecule.
18. The copper nanoparticles according to claim 17, the fatty acid
is 5 to 40 weight % with respect to whole weight.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Korean Patent
Application No. 10-2006-0098315 filed on Oct. 10, 2006, with the
Korea Intellectual Property Office, the contents of which are
incorporated here by reference in their entirety.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a method for manufacturing
copper nanoparticles and copper nanoparticles manufactured using
the same.
[0004] 2. Description of the Related Art
[0005] Noncontact direct writing technology applying inkjet offers
advantages of material and manufacturing time reduction since it
allows discharging an exact amount of ink on an exact position. To
introduce this inkjet method in industrial applications,
corresponding inks should be developed. However, to the present,
there is no metal ink for metal wiring, except a silver
nanoink.
[0006] Silver nanoparticles, which is a major component for the
silver nanoink, has not only a chemical stability but also an
excellent electrical conductance so that it has got paid attention
as an ink material for the metal wiring. Also, noble metal
nanoparticles including silver nanoparticles are easy to be
synthesized and their industrial applicability is enhanced as many
synthetic methods are known. In spite of these advantages, it is
known that, in case of silver, atomic migration or ion migration or
electrochemical migration is easily occurred. This ion migration is
affected by temperature, humidity, and strength of electric field,
etc. In general, ion migration is occurred in high temperature,
high humidity, which further induces short circuit between wires
and increases defect rate. As strength of electric field is
enhanced by micro-wiring, possibility of ion migration is
increased.
[0007] Experimentally, tendency of ion migration is
Ag.sup.+>Pb.sup.2+>Cu.sup.2+>Sn.sup.2+>Au.sup.+.
Considering the tendency of ion migration, gold can be the best
alternative, but its cost is very high. On the other hand,
considering electrical conductivity and cost, copper can be another
good alternative. Presently, wires of electrical units consist of
bulk cooper. Therefore, the ion migration of silver nanoink can be
solved if cooper nanoink is developed.
[0008] Conventional synthetic methods of copper nanoparticles
provide several tens of nm particles. These synthetic methods use
mainly high temperature vapor-phase processes such as thermal
evaporation or thermal plasma. Even though they easily synthesize
copper and other metals, the surface of synthesized copper
particles cannot be treated with an organic dispersing agent. Thus,
it requires re-dispersion and results in a lowered dispersibility
so that it cannot be used as nanoink. Also, the high temperature
vapor-phase method can synthesize only particles with the size more
than several tens of nm and a broad range of size distribution of
particles.
[0009] Recently, a copper nanoparticle synthetic method using
solution synthesis has been suggested. In case of aqueous system,
this method includes methods using micelles or PVP. However, in
case of using micelles, it is impossible to produce copper
nanoparticles in mass production since a copper precursor
concentration which can be used per batch is low.
[0010] As methods of preparing copper nanoparticles with the size
less than several tens of nm, TDMA (thermal decomposition of metal
acetate) suggested by O'Brein et al. has been well-known. This
method is a thermal decomposition of metal acetates such as
Mn(CH.sub.3CO.sub.2).sub.2, Cu(CH.sub.3CO.sub.2) in an oleic acid,
in which the oleic acid functions as a solvent and a capping
molecule. In case of copper nanoparticles, the example using
trioctylamine simultaneously was published in J. Am. Chem. Soc.
2005. Also, Hyeon group published that copper particle synthesis
using the thermal decomposition of copper acetyloacetate
(Cu(acac).sub.2) in oleylamine. These methods are examples that use
the high temperature thermal decomposition in solution.
[0011] Recently, methods for manufacturing copper nanoparticles
using the thermal decomposition have been reported after designing
a copper precursor using the CVD precursor design technique (KR
Patent No. 10-2005-35606). It has an advantage that copper
nanoparticles can be synthesized by the thermal decomposition at a
low temperature of less than 200.degree. C. It, however, requires a
new precursor design and high manufacturing costs.
[0012] Conventional high temperature vapor-phase process is
advantageous for particle synthesis with several tens of nm,
however, particles having dispersing ability cannot be synthesized
and high-cost vacuum equipment is also required. Also, conventional
liquid-phase method requires bulk energy consumption through high
temperature process so that it is not proper in mass production. In
case of using CVD system precursor, commercialized metal salts
cannot be used which is further disadvantage in mass production as
high-cost precursor is used.
SUMMARY
[0013] The present invention was accomplished taking into account
of the problems as described above. The present invention provides
a method for manufacturing copper nanoparticles including:
producing a mixture by dissociating one or more copper salt
selected from a group consisting of CuCl.sub.2, Cu(NO.sub.3).sub.2,
CuSO.sub.4, (CH.sub.3COO).sub.2Cu and Cu(acac).sub.2 (copper
acetyloacetate) in fatty acid; and reacting the mixture by
heating.
[0014] According to an embodiment of the invention, the fatty acid
may include one or more compounds selected from a group consisting
of saturated fatty acids (C.sub.nH.sub.2nO.sub.2), oleic acids
(C.sub.nH.sub.2n-2O.sub.2), lynolic acid
(C.sub.nH.sub.2n-4O.sub.2), lynolene acids
(C.sub.nH.sub.2n-6O.sub.2), and high unsaturated acids
(C.sub.nH.sub.2n-3O.sub.2, C.sub.nH.sub.2n-10O.sub.2,
C.sub.nH.sub.2n-12O.sub.2) (n is an integer of 10-18).
[0015] Also here, the fatty acid may include one or more compounds
selected from a group consisting of dodecarnoic acid
(C.sub.11H.sub.23COOH), oleic acid (C.sub.17H.sub.33COOH),
hexadecanoic acid (C.sub.15H.sub.33COOH), and tetradecanoic acid
(C.sub.13H.sub.27COOH).
[0016] Here, the fatty acid may be mixed in a mole ratio of 2 to 10
with respect to the copper salt.
[0017] According to an embodiment of the invention, a primary
aliphatic amine having carbon numbers of 3 to 18 may be further
added to the mixture. Here, the primary aliphatic amine may be
oleylamine or butylamine. Also here, the primary aliphatic amine
may be added in a mole ratio of 1 to 10 with respect to the copper
salt.
[0018] According to an embodiment of the invention, one or more
nonpolar solvents selected from a group consisting of toluene,
xylene, chloroform, dichloromethane, hexane, tetradecane and
octadecene may be further added to the mixture. Here, the nonpolar
solvent may be added in 200 to 1000 parts by weight with respect to
100 parts by weight of the copper salt.
[0019] Here, the heating temperature may be 50 to 300.degree. C.
Also here, the heating temperature may be 150 to 300.degree. C.
when a thermo-reduction is performed without using a reducing
agent.
[0020] Here, after the reaction of the mixture, adding at least one
reducing agent selected from group consisting of NaBH.sub.4,
LiBH.sub.4, KBH.sub.4, tetrabutylammonium borohydride,
N.sub.2H.sub.4, PhHNNH.sub.2, NH.sub.3--BH.sub.3,
(CH.sub.3).sub.3N--BH.sub.3, formate and NaHPO.sub.2 into the
mixture, and reacting the mixture by heating may be further
included.
[0021] Here, prior to adding the reducing agent, the heating
temperature may be 50 to 110.degree. C.
[0022] Here, the reducing agent may be added in a mole ratio of 1
to 6 with respect to the copper salt.
[0023] Here, the heating temperature of the final mixture may be 50
to 150.degree. C.
[0024] Here, the cooper nanoparticles has size of 5 to 40 nm.
[0025] Another aspect of the invention may provide copper
nanoparticles manufactured by the method for manufacturing copper
nanoparticles set for the above, wherein the surface of the copper
nanoparticles includes fatty acid as a capping molecule.
[0026] Here, the fatty acid may be 5 to 40 weight % with respect to
the total weight.
[0027] Additional aspects and advantages of the present invention
will be set forth in part in the description which follows and, in
part, will be obvious from the description, or may be learned by
practice of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] These and/or other aspects and advantages of the present
invention will become apparent and more readily appreciated from
the following description of the embodiments, taken in conjunction
with the accompanying drawings of which:
[0029] FIG. 1 is a graph representing PXRD (powder X-ray
diffraction) of the copper nanoparticles manufactured according to
example 1 of the invention;
[0030] FIG. 2 is a graph representing PXRD (powder X-ray
diffraction) of the copper nanoparticles manufactured according to
example 2 of the invention; and
[0031] FIG. 3 is a TEM image of the copper nanoparticles
manufactured according to example 2 of the invention.
DETAILED DESCRIPTION
[0032] Hereinafter, preferred embodiments will be described in
detail of the method for manufacturing copper nanoparticles and the
copper nanoparticles thus manufactured according to the present
invention.
[0033] In the invention, to produce copper nanoparticles without
designing a precursor material, copper nanoparticles is synthesized
in a high concentration and a uniform size of copper nanoparticles
using a general copper salt as a copper precursor material in a
non-aqueous system.
[0034] According to an embodiment of the present invention, the
present invention provides a method for producing copper
nanoparticles including: producing a mixture by dissociating one or
more copper salts selected from a group consisting of CuCl.sub.2,
Cu(NO.sub.3).sub.2, CuSO.sub.4, (CH.sub.3COO).sub.2Cu and
Cu(acac).sub.2 (copper acetyloacetate) in fatty acid; and reacting
the mixture by heating.
[0035] The copper precursor material in the present invention may
be a commercialized CuCl.sub.2, Cu(NO.sub.3).sub.2, CuSO.sub.4,
(CH.sub.3COO).sub.2Cu, or Cu(acac).sub.2, etc.
[0036] The fatty acid in the present invention may be a component
that functions as a dispersion stabilizer or a capping molecule and
control the size of copper nanoparticles produced finally and
further guarantee the dispersion stability. The fatty acid may be
saturated fatty acid system (C.sub.nH.sub.2nO.sub.2), oleic acid
system (C.sub.nH.sub.2n-2O.sub.2), linoleic acid system, linolenic
acid system, or high degree unsaturated system
(C.sub.nH.sub.2n-2O.sub.2, C.sub.nH.sub.2n-10O.sub.2,
C.sub.nH.sub.2n-12O.sub.2). Here, n in the above formula is a
positive number of 10-18. Examples of the fatty acid may be one or
more selected from a group consisting of dodecanoic acid
(C.sub.11H.sub.23COOH), oleic acid (C.sub.17H.sub.33COOH),
hexadecanoic acid (C.sub.15H.sub.33COOH) and tetradecanoic acid
(C.sub.13H.sub.27COOH), however, it is not limited to these
examples.
[0037] In the dissociation after adding the copper salt to the
fatty acid, the fatty acid may be mixed in a mole ratio of 2 to 10
with respect to the copper salt. If the content of the fatty acid
is less than 2 mole ratio, the copper salt cannot be perfectly
dissociated. If the content of the fatty acid is more than 10 mole
ratio, productivity is reduced.
[0038] According to one embodiment of the present invention, in the
dissociation of the copper salt, amine compounds can be further
added.
[0039] In the forming of the mixture, examples of the amine
compounds may be a primary aliphatic amine having carbon numbers of
3 to 18. The oleyl amine is used in an example of the present
invention, however, it is not limited to this. The primary
aliphatic amine may be used in a molar ratio of 1 to 10 with
respect to the copper salt. If the content of the primary aliphatic
amine is less than 1 mole ratio, it cannot dissociate the copper
salt efficiently. If the content is more than 10 mole ratio, it may
not isolated and remains with the capping molecule. The amine
compounds dissociate the copper salt in the organic-phase, as well
as, control a reaction velocity.
[0040] According to one embodiment of present invention, in the
dissociation step, the copper salt is mixed directly to the fatty
acid by dissociating without using another organic solvent,
however, a nonpolar solvent may be further added for stable
reaction. The nonpolar solvent may be added independently or as a
mixture of two solvents or more of toluene, xylene, chloroform,
dichloromethane, hexane, tetradecane and octadecene etc. The
nonpolar solvent is added 200 to 1000 parts by weight with respect
to 100 parts by weight of the copper salt. If the content of the
nonpolar solvent is less than 200 parts by weight, the effect of
stable reaction cannot be obtained. If the content of the nonpolar
solvent is more than 1000 parts by weight, productivity is not
preferable.
[0041] The mixture of the copper salt dissociated into the fatty
acid has a green color system.
[0042] After preparing the mixture in which the copper salt is
dissociated, the mixture was heated.
[0043] In the present invention, the reaction temperature and
reaction time can be properly controlled according to the desired
oxidation state of nanoparticles, size of nanoparticles and
reaction condition. The reaction temperature of the mixture in the
heat-reacting is 50 to 300.degree. C. If the temperature is less
than 50.degree. C., reduction of copper ions cannot be properly
performed. If the temperature is more than 300.degree. C.,
available fatty acids are limited. Furthermore, if the reaction
temperature is low, reaction time is excessively elongated. So,
heat reduction is performed in a high temperature, if a reducing
agent is not used, which will be mentioned later. In other words,
among the above range of temperature, high temperature, 150 to
300.degree. C., is preferable. In case of less than 150.degree. C.,
a reaction time cannot be reduced efficiently.
[0044] In the method for manufacturing copper nanoparticles
according to the present invention, to facilitate reduction of
copper ions, a reducing agent can be further added. If the reaction
is performed using the reducing agent, copper ions can be reduced
in a lower temperature within a short period of time.
[0045] According to one embodiment of present invention, the
present invention further includes, after reacting the mixture by
heating, adding at least one reducing agent selected from a group
consisting of NaBH.sub.4, LiBH.sub.4, KBH.sub.4, tetrabutylammonium
borohydride, N.sub.2H.sub.4, PhHNNH.sub.2, NH.sub.3--BH.sub.3,
(CH.sub.3).sub.3N--BH.sub.3, formate and NaHPO.sub.2; and reacting
the mixture by heating.
[0046] When the reducing agent is further added, before adding the
reducing agent, the reaction is heated at a lower temperature, 50
to 110.degree. C., and stirred gently sufficient to dissociate the
copper salt.
[0047] The available reducing agent in the present invention may be
borohydrazines, boranes, hydrazines, formate, sodium
hydrophosphate, etc. More specifically, it may be at least one
compound selected from group consisting of NaBH.sub.4, LiBH.sub.4,
KBH.sub.4, tetrabutylammonium borohydride, N.sub.2H.sub.4,
PhHNNH.sub.2, NH.sub.3--BH.sub.3, (CH.sub.3).sub.3N--BH.sub.3,
formate and NaHPO.sub.2, however, it is not limited to these.
[0048] After preparing the mixture in which the copper salt is
dissociated, the reducing agent is added to it and the mixture is
heated. The content of the reducing agent is 1 to 6 mole ratio with
respect to the copper salt. If the content of the reducing agent is
less than 1 mole ratio, reducing power is too weak to obtain the
desired effect. If the content of the reducing agent is more than 6
mole ratio, the reaction is too explosive to control the reaction.
The content of reducing agent may be determined according to
reaction time, reaction temperature, desirable oxidation state of
copper nanoparticles.
[0049] The temperature in heat reaction after adding the reducing
agent may be 50 to 150.degree. C.
[0050] If the reaction temperature is less than 50.degree. C., it
is difficult to reduce a reaction time. If the reaction temperature
is more than 150.degree. C., the reaction cannot be controlled.
[0051] As the copper ions in the mixture is reduced, color has
changed. The reaction is completed when the color of the mixture
turns to brown or dark red.
[0052] The copper nanoparticles thus manufactured may be obtained
in powder by general filtration, washing and drying processes. For
example, after methanol, acetone or mixture of methanol/acetone is
added, the copper nanoparticles may be obtained by centrifugation.
According to the present invention, the size of copper
nanoparticles is 5 to 40 nm.
[0053] The copper nanoparticles according to another aspect of the
present invention may be manufactured by the above method and the
surface of the copper nanoparticle may include fatty acid as a
capping molecule. The fatty acid forms 5 to 40 weight % among the
total weight.
[0054] The method for manufacturing copper nanoparticles and copper
nanoparticles thus manufactured were set forth above in detail, and
hereinafter, explanations will be given in greater detail with
specific examples. While the embodiment of the present invention
provides the production of copper nanoparticles, the invention is
not limited to the examples stated below and may be used for
production of another copper nanoparticles. It is also apparent
that more changes may be made by those skilled in the art without
departing from the principles and spirit of the present
invention.
EXAMPLE 1
[0055] After Cu(NO.sub.3).sub.2 0.5 mol was added to 2 mol of oleic
acid, 1 mol of butylamine was further added to dissociate. The
color of the reaction solution was changed to green. The reaction
solution was heated to 200.degree. C. with stirring. Then reduction
reaction was processed and color of the reaction solution was
further changed to brown, and copper metal color was appeared at
the wall of a glass reactor. After 2 hours of the reaction,
re-precipitation was performed using a polar solvent a mixture of
acetone and methanol. The copper nanoparticles was recovered using
centrifugation.
EXAMPLE 2
[0056] After 0.5 mol of Cu(CH.sub.3CO.sub.2).sub.2 was added to 1
mol of oleic acid and 300 g of xylene, the mixture was heated to
90.degree. C. while stirring. The color of the reaction solution
was changed to green color. After 1 mol of oleylamine was added to
it and the mixture was further gently mixed, 1 mol of formic acid
was added to it. The mixture was heated to 130.degree. C. and as
the reduction reaction processed, the color of the solution was
changed to brown, and the copper metal color was appeared at the
wall of glass reactor.
[0057] PXRD (powder X-ray diffraction) of the copper nanoparticles
prepared in Example 1 was shown in FIG. 1. From Scherrer-Debye
formula, FIG. 1 ensures that copper nanoparticle with a size of 30
nm was generated.
[0058] PXRD (powder X-ray diffraction) results of the copper
nanoparticles prepared in Example 2 was shown in FIG. 2 and TEM
photo is shown in FIG. 3. From Scherrer-Debye formula, FIG. 2
ensures that the copper nanoparticles with a size of 10 nm was
generated. TEM analysis of FIG. 3 also ensures it.
* * * * *