EP0491163B1

EP0491163B1 - Method and apparatus for producing electrolytic copper foil

Info

Publication number: EP0491163B1
Application number: EP91119338A
Authority: EP
Inventors: Toyoshige C/O Nikko Gould Foil Co. Ltd. Kubo; Katsuhiko C/O Nikko Gould Foil Co.Ltd. Fujishima; Narito C/O Nikko Gould Foil Co.Ltd. Yamamoto
Original assignee: Nikko Materials Co Ltd
Current assignee: Nippon Mining Holdings Inc
Priority date: 1990-12-19
Filing date: 1991-11-13
Publication date: 1996-02-14
Anticipated expiration: 2011-11-13
Also published as: KR940007609B1; EP0491163A1; DE69117155T2; DE69117155D1; MY138622A; KR920012488A

Description

Field of the Invention

This invention relates to a method and apparatus of producing an electrolytic copper foil. More particularly, this invention relates to a method and apparatus of producing an electrolytic copper foil characterized by the provision of a plurality of foil thickness-controlling sub-anodes for uniformizing the thickness of the electrolytic copper foil being made and by the individual control of the quantities of electricity being supplied to the individual foil thickness-controlling sub-anodes. Under this invention, a high-quality electrolytic copper foil with a uniform thickness in the direction of the width or the length or in the directions of both of them is obtained.

Background of the Invention

Electrolytic copper foil is produced by passing a stream of electrolyte between an anode of insoluble metal and a metallic cathode drum mirror-polished on the surface and supplying a potential between the anode and the cathode drum, thereby causing electrodeposition of copper on the cathode drum surface, and, when the electrodeposit has attained a predetermined thickness, peeling the same from the cathode drum. The copper foil thus obtained, called as untreated foil, is thereafter variously surface-treated to be final products.
In the apparatus for manufacturing electrolytic copper foil, the anode after operation for a given time period is worn, above all, to be of no use because it produces an ununiformity in the spacing between itself and the cathode drum. Especially it causes variation in thickness in the direction of the width or the length or both of the foil according to the characteristics peculiar to the apparatus used. FIG. 1 illustrates the relative position of a cathode drum and an anode as divided here into two anode sheets conventionally used for the manufacture of copper foil. In an electrolytic cell (not shown) containing an electrolyte, the cathode drum 1 is installed to be rotatable (clockwise in this case) as partly submerged in the electrolyte. The anode, e.g., two anode sheets 3, is disposed to cover generally the submerged lower half of the cathode drum 1 in spaced relation with a given clearance from the drum surface. Inside the electrolytic cell, the electrolyte is supplied at 6 o'clock position (of the hour hand, the same applying hereinafter) between the two anode sheets 3. It flows upward along the space between the cathode drum and the anode and overflows the upper edges of the anode for circulation. A rectifier 5 maintains a given current between the cathode drum and the anode.
As the cathode drum 1 rotates, the electrodeposit of copper from the electrolyte becomes thicker, and becomes a desired thickness around 9 o'clock position and an untreated foil that has attained a desired thickness is peeled off by suitable peeler means and wound up.
Such an apparatus is known from US-A-3 799 847, wherein a cathode drum is positioned in an electrolythic bath. A first, second, third and fourth anode plate are positioned about the periphery of the cathode drum and radially spaced therefrom. The first anode plate which is the first one in the direction of the progress of electrolytic deposition is secured on a first one of two semi-cylinders making up a housing, while the other anode plates are secured in succession on the other one ofthe two semi-cylinders. The first and the second anode plate are connected to a common source of power supply, and the other anode plates are connected, respectively, to their individual different sources of power supply. In the direction of the progress of the deposition each successive anode plate has a surface area which is smaller than that of the preceding anode plate. The first and the scond anode plate are intended for the formation of a metal band. The third anode plate is intended to ensure sufficient roughness of the surface of this metal band, while the fourth anode plate is intended to ensure formation of an adhesive layer with a highly developed surface on the rough side of the band. For this purpose the current density is successively varied.
In the apparatus for manufacturing electrolytic copper foil, when operation has continued for a given time period, among others, the anode is locally worn with use. Consequently,the space between the cathode drum and the anode sheets varies and the resulting untreated foil becomes uneven particularly in thickness in the direction of the width between side portions and a central portion.
There are produced also variation in thickness along its length due to the lack of uniformity of the factors such as the distance between the anode and the cathode, flow velocity of the electrolyte being supplied, and the quantity of electricity supplied.
Thus, the untreated copper foil so produced varied in its thickness widthwise, lengthwise or in both of them as shown in FIG. 1.
With electrolytic copper foil, one of the important qualitative requirements is that it is uniform in thickness.
To uniformize the thickness of electrolytic copper foil widthwise, the following steps have hitherto been taken:

(1): Anode milling : - With an apparatus for the production of electrolytic copper foil, it has been common that anode after runs for a certain length of time is worn out of use because it makes the space between itself and the cathode drum uneven. As used herein, the expression "out of use" means an abnormal rise of the electrolytic voltage or serious unevenness in thickness of the copper foil produced. In order to avoid this, the anode after service for a given time period is cylindrically reformed on the surface by a special cutting tool.
(2): Partial anode cutting : - After anode milling, variation of thickness in the direction of the width of the resulting copper foil is determined. According to the data thus obtained, the anode surface is partially cut off to correct the thickness of the copper foil properly.

On the other hand, as to the variation in thickness of the length of an electrolytic copper foil produced, little consideration has hitherto been paid.
As stated above, in a conventional countermeasure, the production line must be stopped for correcting the surface of an anode for the purpose of uniformizing the thickness of a copper foil produced and even when the above steps are taken, they could not adequately prevent the variations in thickness of the copper foil produced.
Needless to say, it is in fact impossible to locally control the thickness of the copper foil as desired.
Copper foil is mostly used in printed-circuit boards. The modern tendency with those boards is toward higher density, with finer circuit patterns and thinner layers for higher degrees of multilayer integration. This has not only induced the development of thinner copper foils but has brought increasingly exacting requirements for the uniformity of foil thickness.
Accompanied with this, uniformizing the thickness in the direction of the length that has been overlooked has become a major problem to be solved, needless to mention the uniformity of the thickness in the direction of the width.
The two methods of the prior art described above for uniformizing the thickness in the direction of the width are disadvantageous in that neither permits the correction during the course of operation. They cannot cope with the variations in thickness of the foil in the direction of the width due to uncertain factors originating from causes other than anode, e.g., the thickness variations attributable to the cathode drum or to changes or lack of uniformity of the flow of the electrolyte. Among other shortcomings is the fact that the partial cutting of the anode is time-consuming and cumbersome and renders it not always easy to achieve the end.
FR-A-2 271 306 discloses an apparatus for producing electrolytic metal foils comprising a plurality of anode sections disposed one behind another in the circumferential direction of a rotable cathode drum. The current density of these anode sections connected to a common current source is individually controllable by variable resistances in order to provide a better uniformity of the foil features over the whole thickness the foil.
There is also a need for locally changing or modifying as desired the thickness of a copper foil being produced, but it is in fact impossible to satisfy such need with the production technique presently conducted as already stated.

Object of the Invention

The object of the present invention is to develop a novel method and apparatus of producing electrolytic copper foil which permits the control in thickness of a copper foil including the uniformity of thickness in the directions of width, length or both of the foil during operation and also the correction of thickness variation owing to indefinite and uncertain factors.
An aspect of the subject invention is an apparatus for producing an electrolytic copper foil comprising:

(a): a rotatable cathode drum,
(b): a sheet-shaped anode structure facing the drum and being disposed in spaced relation thereto with a given clearance from the drum surface, said anode structure comprising a main anode portion which is undivided widthwise, and a plurality n of thickness-controlling sub-anodes which are electrically insulated from each other and which are formed by widthwise dividing an end portion of the anode structure at the foil withdrawal side thereof;
(c): means for passing an eletrolyte between the cathode drum and the anode structure.
(d): means for supplying quantities of electricity to said main anode portion and to said sub-anodes thereby electrolytically depositing copper on the drum surface;
(e): means for peeling off the resulting copper deposition as a copper foil from the cathode drum,
(f): means for measuring variations of thickness in the direction of the width of the resulting copper foil as n thicknesses corresponding to the n sub-anodes, and
(g): means for individually increasing or decreasing the quantities of electricity supplied to the n sub-anodes in response to the measured thicknesses so as to uniformize the foil thickness throughout the width thereof.

A further aspect of the subject invention is a method of producing an electrolytic copper foil comprising the steps of:

(a): passing a stream of electrolyte between a rotating cathode drum and a sheet-shaped anode structure facing the drum and being disposed in spaced relation thereto with a given clearance from the drum surface, said anode structure comprising a main anode portion which is undivided widthwise, and a plurality n of thickness-controlling sub-anodes which are electrically insulated from each other and which are formed by widthwise dividing an end portion of the anode structure at the foil withdrawal side thereof;
(b): electrolytically depositing copper on the drum surface by supplying electricity to the main anode and to the sub-anodes independently of one another;
(c): peeling off the resulting copper deposition as a copper foil from the cathode drum,
(d): measuring variations of thickness in the direction of the width of the resulting copper foil as n thicknesses corresponding to the n sub-anodes and
(e): individually increasing or decreasing the quantities of electricity being supplied to the n sub-anodes in response to the measured thicknesses so as to uniformize the foil thickness throughout the width thereof.

Still further aspects of the subject invention are a method of producing an electrolytic copper foil comprising the steps of:

(a): passing a stream of electrolyte between a rotating cathode drum and a sheet-shaped anode structure facing the drum and being disposed in spaced relation thereto with a given clearance from the drum surface, said anode structure comprising a main anode portion which is undivided widthwise, and a plurality n of thickness-controlling sub-anodes which are electrically insulated from each other and which are formed by widthwise dividing an end portion of the anode structure at the foil withdrawal side thereof;
(b): electrolytically depositing copper on the drum surface by supplying electricity to the main anode and to the sub-anodes independently of one another;
(c): peeling off the resulting copper deposition as a copper foil from the cathode drum,
(d): dividing the copper foil area produced per revolution of the cathode drum into n sections widthwise and into m sections lengthwise thus forming n x m sections;
(e): measuring variations of thickness of the resulting copper foil in the n x m sections; and
(f): individually increasing or decreasing the quantities of electricity being supplied to the n sub-anodes in response to the measured thicknesses in the n x m sections so as to uniformize the foil thickness throughout the width and length thereof;

(a): a rotatable cathode drum,
(b): a sheet-shaped anode structure facing the drum and being disposed in spaced relation thereto with a given clearance from the drum surface, said anode structure comprising a main anode portion which is undivided widthwise, and a plurality n of thickness-controlling sub-anodes which are electrically insulated from each other and which are formed by widthwise dividing an end portion of the anode structure at the foil withdrawal side thereof;
(c): means for passing an eletrolyte between the cathode drum and the anode structure;
(d): means for supplying quantities of electricity to said main anode portion and to said sub-anodes thereby electrolytically depositing copper on the drum surface;
(e): means for peeling off the resulting copper deposition as a copper foil from the cathode drum;
(f): means for dividing the copper foil area produced per revolution of the cathode drum into n sections widthwise and into m sections lengthwise thus forming n x m sections;
(g): means for measuring variations of the thickness of the resulting copper foil in the n x m sections; and
(h): means for individually increasing or decreasing the quantities of electricity supplied to the n sub-anodes in response to the measured thicknesses in the n x m sections so as to uniformize the foil thickness throughout the width and length thereof.

Brief Description of the Drawings

FIG. 1 is a diagrammatic perspective view of a main portion of a conventional apparatus for producing electrolytic copper foil.
FIG. 2 is a diagrammatic perspective view of an embodiment of the invention having two anode sheets one of which, on the copper foil-recovering side, is partly divided to provide sub-anodes for controlling the foil thickness widthwise;
FIG. 3 is a perspective view of the anode sheets of FIG. 2;

Description of embodiments

With respect to several embodiments of this invention, explanation will be made with the reference to the drawings wherein common elements are designated by same reference numerals.

(A) Control in the direction of the width:

In accordance with the invention, at least a part of one, preferably at least one on the copper foil-recovering side, of the anode sheets already described with reference to FIG. 1 is divided widthwise into a plurality of sub-anodes for controlling foil thickness widthwise. It is, of course, possible to provide such sub-anodes as auxiliary anodes in addition to an existing anode.
Referring to FIGs. 2 and 3, there is illustrated an embodiment of the invention with a construction such that one of anode sheets, on the copper foil-recovering side, is partly divided into sub-anodes for controlling foil thickness.
The larger the number of sub-anodes the more appropriately the control can be exercised. Greater difficulties will be involved, however, in fabrication and maintenance. Generally, depending on the width of the copper foil to be made and on the conditions of the foil-production equipment used, one anode is divided into from 10 to 40 sub-anodes.
Some apparatus for producing electrolytic copper foil show the tendency of producing a foil especially thin in the central zone or conversely along at least one edge portion. To cope with this, it may be found expedient to split only the central zone or along at least one edge portion, as the case may be, of at least one, or a part of one, of the anode sheets, on the copper foil-recovering side, in the direction of the width, into a plurality of sub-anodes for controlling foil thickness.
Now the operation for the manufacture of electrolytic copper foil will be explained in conjunction with the embodiment shown in FIGs. 2 and 3.
In an electrolytic cell (now shown) which contains an electrolyte such as a sulfuric acid solution of copper sulfate, a cathode drum 1 which is a rotatable cylinder, e.g., of stainless steel or titanium, is held in place by support means, as partly submerged in the electrolyte and made rotatable clockwise in the embodiment shown. There are provided a plurality of, say two, arcuate insoluble anode sheets 3, covering approximately the submerged, lower half part of the cathode drum 1 and spaced a predetermined distance from the drum surface. The anode 3 preferably consists of two anode sheets disposed along at least lower quarter, each, of the cathode drum 1 as shown. According to the necessity, it may be replaced by a single anode sheet or by three, four, or more sheets.
In the embodiment being described, a part of the anode sheet on the copper foil-recovering side is comprised of sub-anodes 4 for controlling foil thickness widthwise, as described above. A suitable number of sub-anodes, 4', 4", 4'", and so forth, are thus provided.
The space between the cathode drum and the anodes is kept constant, usually in the range from 2 to 100 mm. The narrower the space the less the electricity consumption but the more difficult will be the control of the film thickness and quality.
This space between the cathode drum and the anode sheets constitutes a flow passage for the electrolyte. The electrolyte is supplied at 6 o'clock position between two anode sheets 3 by way of a proper pump in the cell (not shown). It passes as divided streams in both directions along the space and overflows the both upper edges of the anode sheets for circulation.
A rectifier 5 maintains a given current between the cathode drum and the anode.
As the cathode drum 1 rotates, electrodeposition of copper from the electrolyte starts, approximately at 3 o'clock position, and the deposit thickness increases until it attains a desired thickness at about 9 o'clock position where the electrodeposition comes to an end. The foil of the desired thickness is peeled off by suitable peeler means at about 12 o'clock position and wound up. The anode, especially of the lead type, is locally worn with use. This results in variation in space between the cathode drum and the anode. In addition, the cathode drum can be responsible for some variation in foil thickness, and the electrolyte stream can undergo a certain deflection or irregularity in flow. Altogether, they tend to cause localized variation in thickness in the direction of the width of the foil.
An explanation is made taking the case where variation in the direction of the width is caused under the above condition of production as an example.
With the embodiment being described, the thickness in the direction of the width of the untreated foil is determined after the peeling and, when a thickness variation beyond a permissible limit has been detected, electrical currents supplied to the specific sub-anodes 4 corresponding to the specific sections in the direction of the width are controlled independently of one another. To permit this individual control of the sub-anodes 4, sub-rectifiers 7 are connected between the individual sub-anodes 4 and the cathode drum 1.
The thickness values at different points in the direction of the width of the copper foil can be simply determined by suitable sampling, in terms of the weight per unit area. Alternatively, a thickness measuring instrument, such as of the static capacity detection type, may be installed in the winding route to monitor the thickness, cooperatively with the sub-rectifiers via feedback means.
Between adjacent sub-anodes is preferably interposed an insulating seal. Useful insulating materials for this purpose include sheets of PVC and cold curable rubber (for example, one marketed under the trade designation "RTV"). Insulation is provided instead by bonding adjacent sub-anodes with an insulating adhesive or integrally joining the sub-anodes with an insulating film therebetween.
Under this embodiment, as described above, an electrolytic copper foil being manufactured can be controlled in thickness including uniformity and local change as desired in thickness by the use of sub-anodes for controlling foil thickness widthwise, through the control of the electric supplies to the individual sub-anodes.
General technical matters explained in the above (A) in detail are applicable to (B) -(C) mentioned below. Accordingly, in (B) -(C) mentioned below, explanations overlapping (A) will be omitted.

(B) Control in the direction of the length:

Referring to FIGs. 2 and 3 there is illustrated an embodiment of the invention with a construction such that one of anode sheets, on the copper foil-recovering side, is partly divided into sub-anodes for controlling foil thickness lengthwise (hereinafter simply called "sub-anodes") 4. As an alternative, the sub-anodes may be replaced by a single sub-anode not divided in the width direction. It is possible to provide such sub-anode(s) as auxiliary anode(s) in addition to an existing anode.
Similarly in the (A), an explanation is made taking the case where the variation in the direction of the length is caused as an example. The operational manner of electrolytic copper foil production is similar to that explained in (A). As the cathode drum 1 rotates, electrodeposition of copper from the electrolyte starts, approximately at 3 o'clock position, and the deposit thickness increases until it attains a desired thickness at about 9 o'clock position where the electrodeposition comes to an end. The foil of the desired thickness is peeled off by suitable peeler means at about 12 o'clock position and wound up.
However, as stated above, localized variation in thickness in the direction of the length of the untreated foil results from factors such as the lack of uniformity of the flow velocity of the electrolyte being fed or of the supply of electricity.
In this embodiment the thickness pattern per revolution of the cathode drum of a sample of the actually formed copper foil is measured at some points in the directions of the length and width. In response to the measured results, a plurality of sub-rectifiers 7 adjust the current supplied between the individual sub-anodes 4 and the cathode drum 1.
For the purposes of the invention the expression "the thickness pattern per revolution of the cathode drum" is used to mean the variation in thickness of the copper foil formed upon one complete turn of the cathode drum measured, e.g., at 720 points chosen by dividing the copper foil area by 36 lengthwise and by 20 widthwise, and then calculating as 36× 20 = 720.
Thus, an electrolytic copper foil being manufactured can be controlled in thickness lengthwise by the use of sub-anodes for controlling foil thickness lengthwise, through the individual control of the quantities of electricity being supplied to the sub-anodes. The copper foil may be uniformized in thickness.

(C) Control in the directions of the width and length:

The operational manner of electrolytic copper foil production is according to the previous explanations.
As the cathode drum rotates, electrodeposition of copper from the electrolyte starts, approximately at 3 o'clock position, and the deposit thickness increases until it attains a desired thickness at about 9 o'clock position where the electrodeposition comes to an end. The foil of the desired thickness is peeled off by suitable peeler means at about 12 o'clock position and wound up.
Taking the case where variation in thickness is caused as an example also herein, an explanation is made. As stated above, localized variation in thickness in the directions of the length and the width of the untreated foil results from factors such as the lack of uniformity of the flow velocity of the electrolyte being fed or of the supply of electricity.
In the embodiments being described, the thickness in the direction of the width of the untreated foil is determined after the peeling and, when the thickness variation has exceeded a permissible limit in any sections, electric currents supplied to the specific sub-anodes 4 in the direction of the width corresponding to the specific sections are controlled independently of one another so as to correct the variation widthwise.
As for the control in the direction of the length, the thickness patterns per revolution of the cathode drum of a sample of the actually formed copper foil is measured at some points lengthwise and widthwise. According to the measured results, a plurality of sub-rectifiers 7 adjust the current supplied between the individual sub-anodes and the cathode drum.
For the purposes of the invention the expression "the thickness pattern per revolution of the cathode drum" is used to mean the variation in thickness of the copper foil formed upon one complete turn of the cathode drum measured, e.g., at 720 points chosen by dividing the copper foil area by 36 lengthwise and by 20 widthwise, and then calculating as 36× 20 = 720.
The variation in thickness of the copper foil is decreased as the number of the division in the directions of the length and the width is increased. When the maintenance of the control means and other considerations for the above purpose are taken into account, a number in the range from 10 to 40 is usually satisfactory.
To permit the individual control of the sub-anodes 4, sub-rectifiers 7 are connected between the individual sub-anodes 4 and the cathode drum 1.
Thus, under this embodiment, an electrolytic copper foil being manufactured can be made controlled in thickness widthwise and lengthwise including uniformity in thickness and any local change as desired in thickness by the use of sub-anodes for controlling the foil thickness widthwise and sub-anodes for controlling the foil thickness lengthwise, through the individual control of the quantities of electricity supplied to the sub-anodes.
As be apparent from the foregoing, this invention permits to effectively uniformize the thickness of a copper foil.
Examples of this invention are set forth below. It is noted that these examples do not intend to restrict this invention.

[Example A-1]

A 35 µm-thick copper foil was made using a copper sulfate solution and a combination of a cathode drum 2.0 m in diameter and 1.3 m in width and two 1.3 m-wide sheets of anode arranged arcuately along substantially the lower half of the cathode drum as shown. The anode structure according to the invention was as depicted in FIGs. 2 and 3 and comprised 20 sub-anodes. On the basis of the weight values per unit area of the peeled copper foil, the electric currents supplied to the individual sub-anodes were adjusted within the range of 0.1 to 10 A/dm. Thus, the method of the invention made it possible to reduce the variation in thickness widthwise, from the usual level of about 3% down to 0.5% or less.

[Example A-2]

The anode structure embodying the invention comprised, 20 sub-anodes arranged on the existing anode sheet as shown in FIG. 1 on the copper foil-recovering side. Otherwise in the same way as in Example A-1, a 35µm-thick copper foil was made. The variation in thickness widthwise of the copper foil thus obtained was 0.5% or less.

[Example B-1]

A 35 µm-thick copper foil was made using a copper sulfate solution and a combination of a cathode drum 2.0 m in diameter and 1.3 m in width and two 1.3 m-wide sheets of anode arranged arcuately along substantially the lower half of the cathode drum as shown. The anode structure according to the invention was as depicted in FIGs. 2 and 3 and a longitudinally divided anode comprised 20 sub-anodes.
On the basis of a lengthwise thickness pattern per revolution of the cathode drum that had been determined beforehand (at 20 widthwise × 36 lengthwise = 720 points), the electric currents supplied to the individual sub-anodes were calculated with a personal computer and adjusted within the range of 0.1 to 10 A/dm. Thus, the method of the invention made it possible to reduce the variation in thickness lengthwise, from the usual level of about 3% down to 0.5% or less.

[Example B-2]

The anode structure embodying the invention comprised, a longitudinally divided anode sheet consisting of 20 sub-anodes arranged on the existing anode sheet as shown in FIG. 1 on the copper foil-recovering side. Otherwise in the same way as in Example B-1, a 35µm-thick copper foil was made. The variation in thickness lengthwise of the copper foil thus obtained was 0.5% or less.

[Example C-2]

The anode structure embodying the invention comprised, a longitudinally divided anode sheet consisting of sub-anodes in the directions of the width and the length, 20 each, arranged on the existing anode sheet as shown in FIG. 1 on the copper foil-recovering side. Otherwise in the same way as in Example C-1, a 35 µm thick copper foil was made. The variation in thickness in the direction of the length and in the direction of the width of the copper foil thus obtained was 0.5% or less.

[Example D-1]

A 35 µm-thick copper foil was made using a copper sulfate solution and a combination of a cathode drum 2.0 m in diameter and 1.3 m in width and two 1.3 m-wide sheets of anode arranged arcuately along substantially the lower half of the cathode drum as shown. The anode structure according to the invention, as depicted in FIGs. 2 and 3 comprised 20 sub-anodes.
On the basis of the combination of thickness patterns in the directions of the length and the width per revolution of the cathode drum that had been determined beforehand (at 20 widthwise × 36 lengthwise = 720 points), the electric currents supplied to the individual sub-anodes were calculated with a personal computer and adjusted within the range of 0.1 to 10 A/dm. Thus, the method of the invention made it possible to reduce the variation in thickness lengthwise and widthwise, from the usual level of about 3% down to 0.5% or less.

[Example D-2]

The anode structure embodying the invention comprised, 20 sub-anodes arranged on the existing anode sheet as shown in FIG. 1 on the copper foil-recovering side. Otherwise in the same way as in Example D-1, a 35µm-thick copper foil was made. The variation in thickness in the direction of the length and in the direction of the width of the copper foil thus obtained was 0.5% or less.

Advantage of the invention

The present invention permits to uniformize or change or modify as desired the thickness of an electrolytic copper foil using foil thickness-controlling sub-anodes in the direction of the width by individually controlling the quantities of electricity supplied to the sub-anodes. Thus, the present invention can accommodate the requirements for electrolytic copper foils for electronic devices and others in future.

Claims

A method of producing an electrolytic copper foil comprising the steps of:
(a) passing a stream of electrolyte between a rotating cathode drum (1) and a sheet-shaped anode structure (3, 4) facing the drum and being disposed in spaced relation thereto with a given clearance from the drum surface, said anode structure comprising a main anode portion (3) which is undivided widthwise, and a plurality n of thickness-controlling sub-anodes (4) which are electrically insulated from each other and which are formed by widthwise dividing an end portion of the anode structure (3, 4) at the foil withdrawal side thereof;

(b) electrolytically depositing copper on the drum surface by supplying electricity to the main anode (3) and to the sub-anodes (4) independently of one another;

(c) peeling off the resulting copper deposition as a copper foil from the cathode drum (1);

(d) measuring variations of thickness in the direction of the width of the resulting copper foil as n thicknesses corresponding to the n sub-anodes (4); and

(e) individually increasing or decreasing the quantities of electricity being supplied to the n sub-anodes (4) in response to the measured thicknesses so as to uniformize the foil thickness throughout the width thereof.
A method of producing an electrolytic copper foil comprising the steps of:
(a) passing a stream of electrolyte between a rotating cathode drum (1) and a sheet-shaped anode structure (3, 4) facing the drum and being disposed in spaced relation thereto with a given clearance from the drum surface, said anode structure comprising a main anode portion (3) which is undivided widthwise, and a plurality n of thickness-controlling sub-anodes (4) which are electrically insulated from each other and which are formed by widthwise dividing an end portion of the anode structure (3, 4) at the foil withdrawal side thereof;

(b) electrolytically depositing copper on the drum surface by supplying electricity to the main anode (3) and to the sub-anodes (4) independently of one another;

(c) peeling off the resulting copper deposition as a copper foil from the cathode drum (1);

(d) dividing the copper foil area produced per revolution of the cathode drum into n sections widthwise and into m sections lengthwise thus forming n x m sections;

(e) measuring variations of thickness of the resulting copper foil in the n x m sections; and

(f) individually increasing or decreasing the quantities of electricity being supplied to the n sub-anodes (4) in response to the measured thicknesses in the n x m sections so as to uniformize the foil thickness throughout the width and length thereof.
The method of claim 1 or 2 wherein the number n of thickness-controlling sub-anodes (4) is from 10 to 40.
The method of claim 2 wherein the number m of lengthwise sections into which the copper foil produced per revolution of the cathode drum is divided, is from 10 to 40.
An apparatus for producing an electrolytic copper foil comprising:
(a) a rotatable cathode drum (1);

(b) a sheet-shaped anode structure (3, 4), facing the drum and being disposed in spaced relation thereto with a given clearance from the drum surface, said anode structure comprising a main anode portion (3) which is undivided widthwise, and a plurality n of thickness-controlling sub-anodes (4) which are electrically insulated from each other and which are formed by widthwise dividing an end portion of the anode structure (3, 4) at the foil withdrawal side thereof;

(c) means for passing an eletrolyte between the cathode drum (1) and the anode structure (3, 4);

(d) means (5, 7) for supplying quantities of electricity to said main anode portion (3) and to said sub-anodes (4), thereby electrolytically depositing copper on the drum surface;

(e) means for peeling off the resulting copper deposition as a copper foil from the cathode drum (1);

(f) means for measuring variations of thickness in the direction of the width of the resulting copper foil as n thicknesses corresponding to the n sub-anodes (4); and

(g) means for individually increasing or decreasing the quantities of electricity supplied to the n sub-anodes (4) in response to the measured thicknesses so as to uniformize the foil thickness throughout the width thereof.
An apparatus for producing an electrolytic copper foil comprising:
(a) a rotatable cathode drum (1);

(b) a sheet-shaped anode structure (3, 4), facing the drum and being disposed in spaced relation thereto with a given clearance from the drum surface, said anode structure comprising a main anode portion (3) which is undivided widthwise, and a plurality n of thickness-controlling sub-anodes (4) which are electrically insulated from each other and which are formed by widthwise dividing an end portion of the anode structure (3, 4) at the foil withdrawal side thereof;

(c) means for passing an eletrolyte between the cathode drum (1) and the anode structure (3, 4);

(d) means (5, 7) for supplying quantities of electricity to said main anode portion (3) and to said sub-anodes (4), thereby electrolytically depositing copper on the drum surface;

(e) means for peeling off the resulting copper deposition as a copper foil from the cathode drum (1);

(f) means for dividing the copper foil area produced per revolution of the cathode drum into n sections widthwise and into m sections lengthwise thus forming n x m sections;

(g) means for measuring variations of the thickness of the resulting copper foil in the n x m sections; and

(h) means for individually increasing or decreasing the quantities of electricity supplied to the n sub-anodes (4) in response to the measured thicknesses in the n x m sections so as to uniformize the foil thickness throughout the width and length thereof.
The apparatus of claim 5 or 6 wherein the number n of thickness-controlling sub-anodes (4) is from 10 to 40.
The apparatus of claim 6 wherein the number m of lengthwise sections into which the copper foil produced per revolution of the cathode drum is divided, is from 10 to 40.