U.S. patent application number 10/713795 was filed with the patent office on 2004-06-03 for electrolyte solution for manufacturing electrolytic copper foil and electrolytic copper foil manufacturing method using the same.
This patent application is currently assigned to ILJIN COPPER FOIL Co., Ltd.. Invention is credited to Kim, Ki-Jung, Kim, Sang-Beom, Lim, Seung-Lin, Yang, Jeom-Sik.
Application Number | 20040104117 10/713795 |
Document ID | / |
Family ID | 29578347 |
Filed Date | 2004-06-03 |
United States Patent
Application |
20040104117 |
Kind Code |
A1 |
Yang, Jeom-Sik ; et
al. |
June 3, 2004 |
Electrolyte solution for manufacturing electrolytic copper foil and
electrolytic copper foil manufacturing method using the same
Abstract
The present invention generally relates to an electrolyte
solution used to manufacture an electrolytic copper foil for a
secondary battery electrode collector and a printed circuit, and
based on a 1-liter electrolyte solution, the present invention
contains: 0.5 to 40 mg of at least one sulfur compound selected
from a disulfur compound, dialkylamino- T-oxomethyl- thioalkan
sulfonic acid, and thioalkan sulfonic acid salt; 1 to 1000 mg of at
least more than one kind of an organic compound selected from a
group consisting of a poly aklylene glycol-type surfactant and low
molecular gelatin; and 0.1 to 80 mg of chlorine ion. The
electrolytic copper foil in accordance with the present invention
has a roughness Rz is less than 2.0 .mu.m, if the electrolytic
copper foil is in a thin film state, and has the roughness Rz value
of the rough surface within a range of 1.0.about.3.5 .mu.m if the
surface of the electrolytic copper foil is treated. Since a
roughness value of a polished surface is changed according to
polishing of a cathode surface, there is no special
restriction.
Inventors: |
Yang, Jeom-Sik; (Seo-gu,
KR) ; Lim, Seung-Lin; (Yeongi-gun, KR) ; Kim,
Sang-Beom; (Yuseong-gu, KR) ; Kim, Ki-Jung;
(Iksan-si, KR) |
Correspondence
Address: |
GARDNER CARTON & DOUGLAS LLP
ATTN: PATENT DOCKET DEPT.
191 N. WACKER DRIVE, SUITE 3700
CHICAGO
IL
60606
US
|
Assignee: |
ILJIN COPPER FOIL Co., Ltd.
Iksan-si
KR
|
Family ID: |
29578347 |
Appl. No.: |
10/713795 |
Filed: |
November 13, 2003 |
Current U.S.
Class: |
205/76 ;
205/291 |
Current CPC
Class: |
C25D 7/0635 20130101;
C25D 3/38 20130101; C25D 1/04 20130101 |
Class at
Publication: |
205/076 ;
205/291 |
International
Class: |
C25D 001/04; C25D
003/38 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 14, 2002 |
KR |
2002-70802 |
Claims
What is claimed is:
1. In an electrolyte solution containing at least selected one of
sulfuric acid and copper sulfate used to manufacture an
electrolytic copper foil by electrolysis, the electrolyte solution
for manufacturing the electrolytic copper foil, based on the
1-liter electrolyte solution, comprising: 0.5 to 40 mg of at least
one sulfur compound selected from a disulfur compound,
dialkylamino- T-oxomethyl- thioalkan sulfonic acid, and thioalkan
sulfonic acid salt; 1 to 1000 mg of at least more than one kind of
an organic compound selected from a group consisting of a poly
aklylene glycol-type surfactant and low molecular gelatin; and 0.1
to 80 mg of chlorine ion added.
2. The electrolyte solution of claim 1, wherein the dialkylamino-
T- oxomethlyl- thioalkan sulfonic acid or the salt thereof is
dithiocarbamic acid compound or salt thereof.
3. The electrolyte solution of claim 1, wherein additives of the
electrolyte solution further include 0.1 to 8 mg/L of thiourea
derivative, a nitrogen compound.
4. The electrolyte solution of claim 1, wherein the disulfur
compound is SPS (Bis-(3-sulfopropyl)-disulfide, disodium
salt)).
5. The electrolyte solution of claim 1, wherein the organic
compound is a poly aklylene glycol-type surfactant.
6. A method of manufacturing an electrolytic copper foil, said
method comprising steps of: A) preparing an electrolyte solution
added with 0.5 to 40 mg of at least one sulfur compound selected
from a disulfur compound, dialkylamino- T-oxomethyl- thioalkan
sulfonic acid, and thioalkan sulfonic acid salt, 1 to 1000 mg of at
least more than one kind of an organic compound selected from a
group consisting of a poly aklylene glycol-type surfactant and low
molecular gelatin, and 0.1 to 80 mg of chlorine ion, based on the
1-liter electrolyte solution; B) generating the electrolytic copper
foil on a cathode by flowing electricity after impregnating an
anode and the cathode with the electrolyte solution.
7. The method of claim 6, wherein the dialkylamino-
T-oxomethyl-thioalkan sulfonic acid is dithiocarbamic acid
compound, and the thioalkan sulfonic acid salt is dithiocarbamic
salt.
8. The method of claim 6, wherein 0.1 to 8 mg/L of thiourea
derivative, a nitrogen compound is further included in the
electrolyte solution.
9. The method of claim 6, wherein the disulfur compound is SPS
(Bis-(3-sulfopropyl)-disulfide, disodium salt).
Description
BACKGROUND OF THE INVENTION
[0001] This application claims the priority of Korean Patent
Application No. 2002-70802 filed on 14 Nov. 2002 in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to an electrolyte
solution used to manufacture an electrolytic copper foil for a
printed circuit and an electrolytic copper foil for an electrode
collector of a secondary battery, the electrolytic copper foil
using the same, and an electrolytic copper foil manufacturing
method thereof.
SUMMARY OF THE INVENTION
[0003] A printed circuit board using the electrolytic copper foil
is widely used as a precise control circuit of various electric,
electronic communication apparatuses such as radios, TVs,
computers, telephone exchanges, wireless transceivers, etc.
Recently, as a degree of integration of the printed circuit board
increases, circuits of the board get minute and multilayered.
Particularly, the electrolytic copper foil is highly demanded in
terms of COF (Chip On Flex) and TAB (Tape Automatic Bonding)
aspects, and is broadly used as an electrode collector of a
secondary battery by improving its physical properties.
[0004] Generally, the electrolytic copper foil is created by
electrolytic methods, and is manufactured from a cylinder-shaped
cathode (also, called a drum) consisting of titanium, an anode
consisting of a lead alloy keeping certain intervals or titanium
covered by an iridium oxide, and an electrolytic cell including an
electrolyte solution and current power. The electrolyte solution is
composed of sulfuric acid and/or a copper sulfate. When DC flows
between the cathode and the anode as rotating the cylinder-shaped
cathode, copper is electrodeposited on the cathode, thereby
consecutively producing the electrolytic copper foil. Thus, a
process of restoring a copper ion to metal with the electrolytic
methods is called a thin film process.
[0005] Next, when necessary, to improve an adhesive force with an
insulating substrate, the copper foil obtained from the thin film
process can pass through additional surface treatment processes
including a roughness treatment process (also, called a nodule
treatment process), a nonproliferation process to prevent the
copper ion from being proliferated, an anticorrosive process to
prevent oxidation from outside, a chemical adhesive force improving
process to complement an adhesive force with the insulating
substrate, and so on. If passing through the surface treatment
process, the copper foil is made for a low profile printed circuit.
And, if only an anticorrosive process of the surface treatment
process is performed, the copper foil is made for the secondary
battery.
[0006] In case the electrodeposited copper foil is used for the
printed circuit, the copper foil is supplied to a PCB (Printed
Circuit Board) process manufacturer while being adhered (laminated)
to the insulating substrate after the surface treatment process.
However, if used for the secondary battery, the copper foil is
supplied to a secondary battery manufacturer via the anticorrosive
process only.
[0007] For the copper foil appropriate for a minute and highly
integrated PCB circuit, the surface of the copper foil contacted
with the insulating substrate should have a small roughness. In
addition, while coupling the electrolytic copper foil with the
insulating substrate, if the copper foil gets stress by thermal
expansion or heat-shrink and moreover, the copper foil is laminated
in multilayer way, it may have scratches due to friction with a
neighboring copper foil. More seriously, the copper foil can be
exfoliated from the insulating substrate or have circuit damage, or
a PCB may get bent or distorted. To protect the copper foil from
these problems, it is necessary to have a proper elongation without
suddenly deteriorating mechanical intensity at high temperature.
When the electrolytic copper foil is used as the collector for the
secondary battery, electrode materials should cover both sides of
the copper foil. In this case, if both sides of the electrolytic
copper foil have a different roughness, battery characteristics
differ from each side. Therefore, it is required to have the same
or a similar roughness on both sides of the electrolytic copper
foil. Furthermore, to reduce weight and a manufacturing cost of the
battery and increase energy density of the battery, the
electrolytic copper foil should be manufactured in thin type. Even
though the copper foil is thin, it is necessary to have sufficient
mechanical intensity and an elongation at high temperature, without
being bent in a future treatment process.
[0008] To satisfy the above requirements, the prior art has
suggested a method of making an electrolytic copper foil by adding
various organic additives to an electrolyte solution. As a
representative example, the U.S. Pat. No. 5,431,803 has been
suggested to lower a surface roughness, providing a method of
manufacturing an electrolytic copper foil that maintains
concentration of a chlorine ion less than 1 mg in a 1-liter
electrolyte solution. However, the electrolytic copper foil
manufactured by a technology suggested in the U.S. Pat. No.
5,431,803 has 61 kgf/mm.sup.2 to 84 kgf/m .sup.2 of mechanical
intensity at room temperature as well as 17 kgf/mm.sup.2 to 25
kgf/mm.sup.2 at 180.degree. C., and has about 6 .mu.m of the
maximum value of the surface roughness: Rmax for a surface
treatment. Thus, it is not appropriate for the secondary battery.
Also, it is difficult to carry out a consecutive operation as
maintaining the concentration of the chlorine ion less than 1 mg in
the electrolyte solution.
SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
provide an electrolyte solution for a printed circuit, an
electrolytic copper foil produced using the same, and a
manufacturing method thereof for controlling a roughness on both
sides of the electrolytic copper foil in the same or similar way
according to electrolyte solution additives and for preventing
sudden intensity changes even at high temperature compared to room
temperature by controlling the amount of the electrolyte solution
additives.
[0010] It is another object of the present invention to provide an
electrolyte solution used to manufacture an electrolytic copper
foil, the electrolytic copper foil produced using the same, and an
electrolytic copper foil manufacturing method thereof for having a
roughness Rz value of a rough surface is less than 2.0 pun in a
thin film state and for preventing sudden intensity changes even at
high temperature compared to room temperature.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0011] To accomplish the above objects, as an electrolyte solution
for manufacturing an electrolytic copper foil, the present
invention provides the electrolyte solution, the electrolytic
copper foil produced by using the electrolyte solution, and an
electrolytic copper foil manufacturing method thereof. In an
electrolyte solution containing at least selected one of sulfuric
acid and copper sulfate used to manufacture an electrolytic copper
foil by electrolysis, the electrolyte solution for manufacturing
the electrolytic copper foil, based on the 1-liter electrolyte
solution, comprising: 0.5 to 40 mg of at least one sulfur compound
selected from a disulfur compound, dialkylamino- T-oxomethyl-
thioalkan sulfonic acid, and thioalkan sulfonic acid salt; 1 to
1000 mg of at least more than one kind of an organic compound
selected from a group consisting of a poly aklylene glycol-type
surfactant and low molecular gelatin; and 0.1 to 80 mg of chlorine
ion added.
[0012] A solution comprising i) sulfuric acid and copper salt
rather than copper sulfate, or ii) copper sulfate and acid rather
than sulfuric acid may be also used as the electrolyte.
[0013] The organic compound comprising low molecular gelatin
without polyalkylene gulycol type surfactant may be also used as
the organic compound.
[0014] Generally, a process of manufacturing an electrolytic copper
foil for a printed circuit is divided into a thin film process and
a surface treatment process.
[0015] The thin film process is generally performed by using an
electroforming cell. Within an electrolytic cell, a semi-cylinder
type anode and a cylinder-type rotating cathode are located at
certain intervals, and the electrolyte solution is consecutively
supplied between the anode and the cathode. By flowing DC between
the anode and the cathode, a copper ion of the electrolyte solution
is restored to metal having predetermined thickness from the
cathode. Next, a copper foil (undisposed) that does not pass
through a future treatment process is exfoliated from the surface
of the cathode. A lead alloy is widely used for the anode, but
recently, intervals are changed by corrosion of a lead oxide.
Therefore, titanium covering an iridium oxide is more used. The
cathode is used by plating iron with chromium, however recently,
stainless materials are covered with titanium to lengthen the span
of life.
[0016] Next, to provide requested characteristics when necessary,
an additional treatment process of passing the undisposed copper
foil through a processor can be performed. This treatment process
includes a roughness treatment process to improve an adhesive force
when laminated on an insulating substrate, a nonproliferation
process to prevent a copper ion from being proliferated, and an
anticorrosive process to prevent oxidation during storage,
transportation or a lamination forming process of the copper foil
and the insulating substrate. Hereinafter, the above processes will
be more fully described. The above processes are performed in the
processor having the anode, and a surface treatment copper foil is
finally obtained through these processes.
[0017] The electrolyte solution supplied between the anode and the
cathode is a copper sulfate solution, and its blending based on 1
liter is as follows:
[0018] Copper concentration is between 50 g and 110 g, and
desirably, between 60 g and 100 g. Sulfuric acid concentration is
between 80 g and 200 g, and desirably, between 90 g and 120 g.
Temperature of the electrolyte solution is between 40.degree. C.
and 80.degree. C. Current density is between 400A/cm.sup.2 and
10000A/dm.sup.2, and desirably, between 50A/dm.sup.2 and
85A/dm.sup.2. If the copper concentration is less than 50 g, the
surface of an electrodeposited copper foil is rough and powder is
formed, lowering productivity. However, if more than 110 g, the
electrolyte solution is crystallized, deteriorating working
efficiency. If the sulfuric acid concentration is less than 80 g,
an electrolytic voltage rises, resulting in an increase of
production cost. Also, temperature of the electrolyte solution
rises, causing deterioration of mechanical intensity of the copper
foil. If the sulfuric acid concentration is more than 200 g, the
electrolyte solution is highly apt to be corrosive even though the
electrolytic voltage lowers, thereby quickly corroding an electrode
electrolyzing the copper foil.
[0019] At this time, the electrolyte solution contains a sulfur
compound having 0.5 to 40 mg of concentration and at least more
than one kind of an organic compound selected from a group
consisting of a poly alkylene glycol-type surfactant having 1 to
1000 mg of concentration and low molecular gelatin as additives. In
addition, a chlorine ion having a range of 0.1 mg to 80 mg is
added.
[0020] More desirably, to increase intensity of the electrolytic
copper foil produced by the electrolyte solution, it is possible to
use a nitrogen compound. For a thiourea derivative, which is the
nitrogen compound, IM(2-imidazolidiniethionie) is used within a
range of 0.1 mg to 8 mg. As for the poly alkylene glycol-type
surfactant, it is available to use poly ethylene-type, poly
propylene-type, and poly butylenes-type surfactants. Particularly,
poly ethylene glycol can be representative of the poly
ethylene-type surfactant.
[0021] A disulfur compound and dialkylamino- T-oxomethyl- thioalkan
sulfonic acid or thioalkan sulfonic acid salt are included in the
sulfur compound. The disulfur compound includes SPS
(Bis-(3-sulfopropyl)-disulfi- de, disodium salt)), and
dialkylamino- T-oxomethyl- thioalkan sulfonic acid or salt thereof
can contain dithiocarbamic acid or salt thereof, and DPS
(N,N-Dimethyldithiocarbamic acid (3-sulfopropyl) ester, sodium
salt) is representative. A formula of the dialkylamino-
T-oxomethyl- thioalkan sulfonic acid or the salt thereof is shown
in a chemical formula 1, and a formula of the DPS as a
representative example is shown in a chemical formula 2, then a
formula of the SPS is shown in a chemical formula 3. 1
[0022] `R` in the chemical formula 1 means an alkyl group (carbon
atom 1.about.6), `n` is 2.about.3 (ethane, propane), and `X` means
hydrogen atom or alkali metal atom. 2
[0023] Among the above additives, the roles of the sulfur compound
and the surfactant are very important, since these compounds give
direct influence on a surface roughness and tensile strength.
Compared to a general electrolytic copper foil added with glue or
gelatin, the sulfur compound generally has a small size of grains
and functions as a grain refiner or a brightener. The added
surfactant functions as a carrier or an electrodeposition leveler
lowering a surface roughness of a mat surface of the electrolytic
copper foil, influencing electroposition. In this case, the
surfactant is absorbed into a protruded part of an electrode
surface as carrying the sulfur compound, which is a brightener, to
a cathode surface, and suppresses growth of the protruded part,
thereby interrupting the growth firstly. And the sulfur compound,
which is the grain refiner, firstly functions in a minute valley
part of an electroposition surface, and enables a copper ion to be
restored and grow up in this part first of all, thereby controlling
a roughness of the electrodeposition surface.
[0024] The thiourea derivative, the nitrogen compound used in the
present invention suppresses crystal growth of copper at room
temperature or high temperature by eutectoid-processing nitrogen on
an electrodeposition layer, and also restrains strength
deterioration. Thus, when the nitrogen compound, the thiourea
derivative is added, it is possible to prevent the strength
deterioration, which occurs otherwise. So, a defective proportion
caused when dealing with the electrolytic copper foil or
manufacturing the printed circuit can be reduced. Moreover, the
strength can be changed by controlling an amount of the additives,
thereby adjusting physical properties of the electrolytic copper
foil.
[0025] For the electrolytic copper foil in accordance with the
present invention, if it is undisposed, it seems that a roughness
of a rough surface (mat surface) has an Rz value having a range of
2.0 .mu.m. RZ has been measured by an IPC TM 650 2.2.17A method.
For other copper foil passing through surface treatment, it seems
that the roughness of the rough surface (mat surface) has an Rz
value having a range of 1.0.about.3.5 .mu.m. Since a roughness
value of a drum surface (bright surface) of the copper foil
contacted with the drum surface is produced according to polishing
of the drum surface, there is no particular restriction.
[0026] In order to improve an adhesive force with an insulating
substrate, if necessary, the above undisposed copper foil can pass
through additional surface treatment processes including a
roughness treatment process (also, called a nodule treatment
process), a nonproliferation process to prevent a copper ion from
being proliferated, and an anticorrosive process to prevent
oxidation from outside. If passing through the surface treatment
process, the copper foil is made for a low profile printed circuit,
however, if passing through the anticorrosive process only, the
copper foil is for a secondary battery.
[0027] The roughness treatment process consists of two steps or
three steps. In a first step, a core of minute powder is made, and
the powder is coupled with the copper foil in a second step because
the powder does not have an adhesive force with the copper foil. In
a third step, a minute protrusion is given to the coupled powder
again. The first step is as follows. Based on a 1-liter electrolyte
solution, copper concentration is between 10 g and 40 g, and
desirably, between 15 g and 25 g. Sulfuric acid concentration is
between 40 g and 150 g, and desirably between 60 g and 100 g, and
temperature of the electrolyte solution is between 20.degree. C.
and 40.degree. C.
[0028] Current density is between 20 A/dm.sup.2 and 100 A/dm.sup.2,
and desirably, between 40 A/dm.sup.2 and 80 A/dm.sup.2. The second
step is as follows. Copper concentration is between 50 g and 110 g,
and desirably, between 55 g and 100 g. Sulfuric acid concentration
is between 80 g and 200 g, and desirably, between 90 g and 120 g.
Temperature of the electrolyte solution is between 40.degree. C.
and 80.degree. C. Current density is between 20 A/dm.sup.2 and 100
A/dm.sup.2, and desirably, between 40 A/dm.sup.2 and 80 A/dm.sup.2.
The nonproliferation process is as follows. To prevent the copper
ion from being proliferated, a barrier layer is formed with various
single metal such as zinc, nickel, iron, cobalt, molybdenum,
tungsten, tin, indium, and chrome, or with 2 or 3 kinds of
alloys.
[0029] Then, to prevent oxidation during storage, transportation,
or a lamination forming process of the copper foil and the
insulating substrate, the anticorrosive process is carried out. The
anticorrosive process performs chromate passivation with chromic
acid, sodium dichromate, potassium dichromate, chromic anhydride,
etc. Next, a process for increasing chemical cohesion is
executed.
[0030] Also, a chemical adhesive force improving process can be
carried out to complement an adhesive force with the insulating
substrate. For this, there are usable adhesion accelerators such as
a silane coupling agent (RSiX.sub.3), silicon peroxygen
(R.sub.4-nSi(OOR').sub.n), a chromium-based adhesion accelerator
((RCO.sub.2H.sub.3OHCrOHCrHOH.sub.2).- sub.2OH), an organic
titanium based adhesion accelerator
((C.sub.4H.sub.9CHC.sub.2H.sub.5CH.sub.2O).sub.4Ti), an organic
phosphate based adhesion accelerator (RO.sub.2P(OH).sub.2), and
others.
[0031] Embodiments
[0032] Hereinafter, the present invention will be described in
reference to the embodiments and compared examples. Here, a symbol
`g/L` means a content of a corresponding material based on a
1-liter electrolyte solution.
[0033] For a thin film process, the electrolyte solution having
blending like described in Table 1 is prepared. Copper
concentration of the electrolyte solution is 80 g/L, sulfuric acid
concentration is 90 g/L, and temperature of the electrolyte
solution is 45.degree. C. Additives like described in Table 1 have
been added. Current density was electrodeposited in 60 A/dm.sup.2,
and chlorine ion was maintained in 25 mg/L.
[0034] For embodiment 1, 6 mg/L of DPS(N,N-Dimethyldithiocarbamic
acid (3-sulfopropyl) ester, sodium salt) was used as a sulfur
compound, and 1 mg/L of PEG (Poly Ethylene Glycol) was used as a
poly alkylene glycol-type surfactant.
[0035] For embodiment 2, 1 mg/L of SPS
(Bis-(3-sulfopropyl)-disulfide, disodium salt) was used as a sulfur
compound, and 30 mg/L of PEG (Poly Ethylene Glycol) was used as a
poly alkylene glycol-type surfactant.
[0036] For embodiment 3, 30 mg/L of DPS(N,N-Dimethyldilhiocarbamic
acid (3-sulfopropyl) ester, sodium salt) was used as a sulfur
compound, and 30 mg/L of PEG (Poly Ethylene Glycol) was used as a
poly alkylene glycol-type surfactant.
[0037] For embodiment 4, 5 mg/L of SPS
(Bis-(3-sulfopropyl)-disulfide, disodium salt) was used as a sulfur
compound, and 1 mg/L of PEG (Poly Ethylene Glycol) was used as a
poly alkylene glycol-type surfactant.
[0038] For embodiment 5, 3 mg/L of DPS(N,N-Dimethyldilhiocarbamic
acid (3-sulfopropyl) ester, sodium salt) was used as a sulfur
compound, and 800 mg/L of PPG (Poly Propylene Glycol) and 5 mg/L of
low molecular gelatin less than molecular weight 6000 were added as
a poly ethylene glycol surfactant.
[0039] For embodiment 6, 5 mg/L of SPS
(Bis-(3-sulfopropyl)-disulfide, disodium salt) was used as a sulfur
compound, 0.5 mg/L of IM (2-imiidazolidinetihione), which was a
thiourea derivative, was as a nitrogen compound, and 25 mg/L of PEG
(Poly Ethylene Glycol) was used as a poly ethylene glycol-type
surfactant.
[0040] For embodiment 7, 3 mg/L of SPS
(Bis-(3-sulfopropyl)-disulfide, disodium salt) and 5 mg/L of
DPS(N,N-Dimethyldithiocarbamic acid (3-sulfopropyl) ester, sodium
salt) were as a sulfur compound, and 30 mg/L of PEG (Poly ethylene
glycol) and 30 mg/L of PPG (Poly Propylene Glycol) were used as a
poly ethylene glycol-type surfactant.
[0041] By using the electrolyte solution prepared like above, a
titanium anode covering an iridium oxide, and a rotating
cylinder-type titanium cathode, the undisposed copper foil
corresponding to the embodiments 1 to 7 was obtained, respectively,
under an electrolytic condition like described in Table 1.
[0042] In case of the sulfur compound, an Rz value tended to exceed
2.0 .mu.m by an increase of a surface roughness of a rough surface
in a range of exceeding 40 mg/L. When used less than 0.5 mg/L, the
surface roughness did not lower, rather the roughness increased as
lowering an elongation. As for the poly ethylene glycol-type
surfactant, it was possible to confirm a function of lowering the
surface roughness of the rough surface within a range of 1 mg/L to
1000 mg/L. More desirably, a desirable surface roughness could be
obtained within a range of 1 mg/L to 300 mg/L. However, in this
case, it was required to control using current density in higher or
lower way according to its amount. For the sulfur compound and the
poly ethylene glycol-type surfactant, if concentration was higher
than an upper limit above, the surface got rough and burning
phenomenon (electrodeposited into powder) occurred. Thus, they
might not be usable for manufacturing a satisfactory electrolytic
copper foil.
[0043] So as to control hardness of the manufactured electrolytic
copper foil, it was proper to have a range of 0.1 mg/L to 8 mg/L
for the nitrogen compound additionally included to form the
electrolyte solution. If an amount of an additive was too little,
the hardness got slightly improved, and if too much, the hardness
got higher but a surface roughness rose, thereby lowering an
elongation.
[0044] For each of the undisposed copper foil, a surface roughness
Rz was measured according to an IPC TM 650 2.2.17A method, and an
elongation and tensile strength of the copper foil have been
measured at room temperature (25.degree. C.) and 180.degree. C.
according to an IPC TM 650 standard processing method. The results
are shown in Table 2.
[0045] Next, a surface treatment process was carried out for the
undisposed copper foil in accordance with the embodiments 1 to 7.
First, for a nonproliferation process, 110 g/L of sodium cyanide,
60 g/L of sodium hydroxide, 90 g/L of copper cyanide, and 5.3 g/L
of zinc cyanide have been electrodeposited with pH 11.0 to 11.5 at
50.degree. C., having 5 A/dm.sup.2 of current density for 10
seconds. For an anticorrosive process, 10 g/L of sodium dichromate
has been measured with pH 4.5, having 0.5 A/dm.sup.2 of current
density for 2 seconds.
COMPARED EXAMPLES
[0046] The composition of the electrolyte solution and the chlorine
ion concentration are the same as the above embodiments. For a
compared example 1, 2 mg/L of low molecular gelatin less than 6000
molecular weight has been added as an additive. For a compared
example 2, 1 mg/L of TU (thiourea) has been added with 2 mg/L of
low molecular gelatin less than 6000 molecular weight. For a
compared example 3, 50 mg/L and 30 mg/L of SPS and PEG,
respectively, have been added. And for a compared example 4, 3 mg/L
and 1500 mg/L of DPS and PPG, respectively, have been added.
[0047] Under the electrolytic condition described in Table 1, the
undisposed copper foils corresponding to the compared examples 1 to
4 have been obtained, as well as a surface roughness Rz for the
undisposed copper foils, and an elongation and tensile strength
were measured at room temperature (25.degree. C.) and 180.degree.
C. by an IPC IM 650 2.4.18A method. The results are shown in Table
2. Next, a surface treatment process has been carried out for the
undisposed copper foils in accordance with the compared examples 1
to 4.
[0048] Table 2 shows the results of comparing physical properties
of the copper foil tentatively manufactured through the embodiments
and the compared examples under the condition suggested in Table
1.
[0049] Like displayed in Table 2, according to the embodiments in
accordance with the present invention, a roughness (Rz) of a rough
surface is controlled less than 2.0 by the sulfur compound. Thus,
it is possible to maintain similarly to a roughness (Rz) of a drum
surface and change strength by controlling an amount of the
thiourea derivative, the nitrogen compound, thereby enabling the
electrolytic copper foil to be manufactured for various
purposes.
1 TABLE 1 Additives Solution Low Composition Molecular Copper
Sulfur SPS DPS IM PEG PPG Gelatin TU Cl- (g/L: Acid (mg/L) (mg/L)
(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Ion) (g/L) Embodiment 1
-- 6 -- 1 -- -- -- Embodiment 2 1 -- -- 30 -- -- -- Embodiment 3 --
30 -- 30 -- -- -- Embodiment 4 5 -- -- 1 -- -- -- Embodiment 5 -- 3
-- -- 800 5 -- Embodiment 6 5 -- 0.5 25 -- -- -- Embodiment 7 3 5
-- 30 30 -- -- Compared -- -- -- -- -- 2 -- 25 80 90 Example 1
Compared -- -- -- -- -- 2 1 Example 2 Compared 50 -- -- 30 -- -- --
Example 3 Compared -- 3 -- -- 1500 -- -- Example 4
[0050] Current density: 60 A/dm.sup.2, Solution temperature:
45.degree. C.
[0051] DPS: N-Dimethyldithiocarbamic acid (3-sulfopropyl) ester,
sodium salt
[0052] SPS: Bis-(3-sulfopropyl)-disulfide, disodium salt
[0053] IM: 2-imidazolidinethione
[0054] PEG: Poly Ethylene Glycol
[0055] PPG: Poly Propylene Glycol
[0056] Low molecular gelatin: gelatin less than 6000 molecular
weight
[0057] TU: thiourea
2 TABLE 2 Surface Surface Tensile Roughness Roughness Strength
Elongation Tensile of Rough of Drum (Room (Room Strength Elongation
Surface Surface Temperature) Temperature) (180.degree. C.)
(180.degree. C.) (Rz:.mu.m) (Rz:.mu.m) (kgf/mm.sup.2) (%)
(kfg/mm.sup.2) (%) Embodiment 1 1.52 1.68 33.2 8.9 22.5 7.6
Embodiment 2 1.83 1.76 29.5 9.6 20.9 8.0 Embodiment 3 1.42 1.84
33.4 12.9 22.2 14.4 Embodiment 4 1.88 1.91 30.4 12.9 20.6 10.6
Embodiment 5 1.81 1.79 31.4 4.1 18.4 3.1 Embodiment 6 0.50 1.75
33.2 11.4 23.6 6.0 Embodiment 7 1.14 1.55 32.0 8.8 20.6 4.2
Compared 3.53 1.81 37.1 5.6 22.8 2.2 Example 1 Compared 1.9 1.85
49.0 1.5 22.0 1.9 Example 2 Compared 2.23 1.88 34.2 1.9 22.2 3.5
Example 3 Compared 2.38 1.79 13.9 0.23 16.9 1.2 Example 4
[0058] Like shown in the embodiments 1 to 7 suggested in Table 2,
the electrolytic copper foil manufactured in the embodiments in
accordance with the present invention has a surface roughness Rz
value of a rough surface within a range of 2.0 .mu.m in a thin film
state. It is also confirmed that tensile strength at room
temperature is not rapidly changed even at high temperature
(180.degree. C.) as well.
RESULTS OF THE INVENTION
[0059] An electrolytic copper foil in accordance with the present
invention has a roughness Rz value of a rough surface (mat surface)
with a range of less than 2.0 .mu.m, if undisposed. However, if the
copper foil passes through a surface treatment process, it has a
roughness Rz value of a rough surface (mat surface) within a range
of 1.0.about.3.5 .mu.m. Therefore, the electrolytic copper foil in
accordance with the present invention has a relatively lower
roughness on the rough surface, and both sides of the electrolytic
copper foil have a similar roughness.
[0060] An electrolytic copper foil manufactured in prior art has a
problem of rapidly causing strength deterioration at high
temperature (180.degree. C.), though good strength is maintained at
room temperature. However, the electrolytic copper foil in
accordance with the present invention does not show any sudden
strength change even at high temperature. Accordingly, the
electrolytic copper foil in accordance with the present invention
is appropriate for a minute and highly integrated PCB circuit.
[0061] Furthermore, when used as a collector for a secondary
battery, a more reliable battery characteristic can be obtained,
since a roughness on both sides of the electrolytic copper foil is
similar. The electrolytic copper foil in accordance with the
present invention prevents tensile strength from suddenly
deteriorating owing to a temperature rise, having excellent
elongation characteristics at room temperature and high
temperature. Thus, it would not get bent or distorted in a future
treatment process nor generate a short circuit. The electrolytic
copper foil in accordance with the present invention is proper to
be used as the collector for the secondary battery or a printed
circuit board.
[0062] It is to be understood that changes and modifications to the
embodiments described above will be apparent to those skilled in
the art, and are contemplated. It is therefore intended that the
foregoing detailed description be regarded as illustrative rather
than limiting, and that it be understood that it is the following
claims, including all equivalents, that are intended to define the
spirit and scope of this invention.
* * * * *