Metal foil production device and electrode

Abstract

A metal foil production device for producing a metal foil via electroplating comprises: an electrolytic bath that holds an electrolytic solution; a drum-like first electrode (3) that is rotatably provided in the electrolytic bath; and a second electrode (4) that is provided in the electrolytic bath so as to face an outer peripheral surface of the first electrode (3). The second electrode (4) includes a base (40), an electrode plate (50) that is provided on the base (40), and a fixture (60) that fixes the base (40) and the electrode plate (50). The gap dimension (G1) between an upper surface (60a) of the fixture (60) and a surface (3a) of the first electrode (3) is less than a gap dimension (G2) between a surface (50a) of the electrode plate (50) and the surface (3a) of the first electrode (3).

Description

Metal Foil Manufacturing Apparatus and Electrode

[0001] The present invention relates to a metal foil manufacturing apparatus and an electrode.

[0002] Metal foils are widely used industrially, for example, as printed circuit materials in the electrical and electronic fields, and as current collectors for batteries in the electrochemical field. Such metal foils are often manufactured using electroplating, since this method can relatively easily obtain continuous metal foils with excellent surface smoothness. An example of a metal foil manufacturing apparatus for producing a metal foil (electrolytic metal foil) by electroplating is disclosed in Utility Model Registration No. 3239183 (Patent Document 1).

[0003] The metal foil manufacturing apparatus of Patent Document 1 comprises an electrolytic cell (cell body 102) holding an electrolytic solution, a drum-shaped first electrode (cathode 103) rotatably provided in the electrolytic cell, and a second electrode (anode 104) provided in the electrolytic cell so as to face the outer peripheral surface of the first electrode. The second electrode includes a base (electrode base 3), an electrode plate (thin-plate electrode 7) provided on the base, and a fixture (flathead screw 5) for fixing the base and the electrode plate together. In the metal foil manufacturing apparatus of Patent Document 1, the upper surface of the fixture is flush with the surface of the electrode plate.

[0004] Utility Model Registration No. 3239183

[0005] However, when the upper surface of the fixture is flush with the surface of the electrode plate, the thickness of the obtained metal foil may become non-uniform. Non-uniform thickness of the metal foil is not preferable in terms of product quality.

[0006] Therefore, it is desired to realize a metal foil manufacturing apparatus capable of manufacturing a metal foil with small thickness variation with a relatively simple configuration, and an electrode used therefor.

[0007] The metal foil manufacturing apparatus according to the present invention is a metal foil manufacturing apparatus for manufacturing metal foil by electroplating, comprising: an electrolytic cell for holding an electrolyte; a drum-shaped first electrode rotatably mounted in the electrolytic cell; and a second electrode provided in the electrolytic cell so as to face the outer circumferential surface of the first electrode, wherein the second electrode includes a base body, an electrode plate provided on the base body, and a fixing device for fixing the base body and the electrode plate, wherein the gap dimension between the upper surface of the fixing device and the surface of the first electrode is smaller than the gap dimension between the surface of the electrode plate and the surface of the first electrode.

[0008] The inventors hypothesized that the reason the thickness of the metal foil obtained by electroplating is uneven is that the ease with which current flows differs depending on the position of the second electrode. They then reasoned that the reason the ease with which current flows differs depending on the position of the second electrode is that current does not flow as easily through the fixing device, which also constitutes the second electrode, compared to the electrode plate that constitutes the second electrode.

[0009] In view of this, the present invention makes the gap between the upper surface of the fixing device and the surface of the first electrode smaller than the gap between the surface of the electrode plate and the surface of the first electrode. By doing so, the electrical resistance between the first electrode and the fixing device is made smaller than the electrical resistance between the first electrode and the electrode plate, thereby improving the resistance of current flow at the position of the fixing device. As a result, the difference between the current flowing at the electrode plate and the current flowing at the fixing device can be minimized, and as a result, the variation in the thickness of the resulting metal foil can be reduced. Moreover, the above effect can be obtained simply by adjusting the gap between the surface of the first electrode at each position of the electrode plate and the fixing device. Therefore, a metal foil manufacturing apparatus can be provided that can manufacture metal foil with less variation in thickness with a relatively simple configuration.

[0010] Preferred embodiments of the present invention will be described below. However, the scope of the present invention is not limited by the examples of preferred embodiments described below.

[0011] In one embodiment, the fixing device has a shaft portion that penetrates the electrode plate and is fastened to the base body, and a head portion connected to the upper end of the shaft portion that holds down the electrode plate, wherein the ratio of the head portion's protrusion height from the surface of the electrode plate to the head portion's diameter is preferably 1 / 20 to 1 / 5.

[0012] This configuration allows for a moderate reduction in electrical resistance between the first electrode and the fixing device, minimizing the difference between the current flowing through the electrode plate and the current flowing through the fixing device. Therefore, variations in the thickness of the resulting metal foil can be minimized.

[0013] In one embodiment, the fixing device has a head that is operated by a fixing tool, and a shaft that extends downward from the head, penetrates the electrode plate, and is fastened to the base, the head has an enlarged diameter portion that gradually increases in diameter relative to the diameter of the shaft, and a thickened portion that extends above the enlarged diameter portion, the electrode plate has a frustoconical surface around a through hole through which the shaft penetrates, which has a shape complementary to the enlarged diameter portion, and it is preferable that the frustoconical surface and the enlarged diameter portion are in contact with each other when the fixing device is fixed to the base and the electrode plate, and the thickened portion protrudes from the surface of the electrode plate.

[0014] With this configuration, a simple modification to a so-called countersunk screw, which has a head consisting of an enlarged diameter portion and a shaft portion extending downward from that head, is made by adding a thickened portion to the head that extends above the enlarged diameter portion. This makes it possible to reduce the gap between the upper surface of the fastener and the surface of the first electrode. Therefore, the difference between the current flowing through the electrode plate and the current flowing through the fastener can be minimized, and variations in the thickness of the resulting metal foil can be reduced.

[0015] In one embodiment, it is preferable that the ratio of the thickness of the increased-walled portion to the thickness of the enlarged-diameter portion is 1 / 5 to 1 / 2.

[0016] This configuration allows for a moderate reduction in electrical resistance between the first electrode and the fixing device, minimizing the difference between the current flowing through the electrode plate and the current flowing through the fixing device. Therefore, variations in the thickness of the resulting metal foil can be minimized.

[0017] In one embodiment, the fixing device has a head formed with a locking hole into which a fixing tool is locked, a catalyst layer is provided on the upper surface of the head, and it is preferable that the ratio of the minimum opening width of the locking hole to the depth of the locking hole is 1 / 2 or more.

[0018] With this configuration, the opening width of the locking hole formed in the head of the fixing device is sufficiently large, making it easier to properly form the catalyst layer on the inner surface (bottom and sides) of the locking hole. Therefore, the difficulty of current flow at the position of the fixing device can be improved, including the inner surface of the locking hole. As a result, variations in the thickness of the resulting metal foil can be minimized.

[0019] In one embodiment, it is preferable that the locking hole is formed in a regular polygonal shape when viewed from above.

[0020] This configuration allows for the proper formation of locking holes with a minimum opening width-to-depth ratio of 1 / 2 or greater, and facilitates the proper formation of a catalyst layer on the inner surface (bottom and sides) of the locking holes. Furthermore, the substrate and electrode plate can be fixed together using a fixing device with wrenches of various commonly available shapes as fixing tools.

[0021] The electrode according to the present invention is an electrode used in the manufacture of electrolytic metal foil, and includes a substrate, an electrode plate provided on the substrate, and a fixing device for fixing the substrate and the electrode plate, and is arranged opposite a rotatably mounted drum-shaped counter electrode, wherein the gap between the upper surface of the fixing device and the surface of the counter electrode is smaller than the gap between the surface of the electrode plate and the surface of the counter electrode.

[0022] In this configuration, when the fixing device is positioned opposite the drum-shaped counter electrode, the gap between the top surface of the fixing device and the surface of the counter electrode becomes smaller than the gap between the surface of the electrode plate and the surface of the counter electrode. Therefore, the electrical resistance between the counter electrode and the fixing device can be made smaller than the electrical resistance between the counter electrode and the electrode plate, improving the resistance of current flow at the position of the fixing device. This minimizes the difference between the current flowing at the electrode plate and the current flowing at the fixing device, and as a result, the variation in the thickness of the resulting electrolytic metal foil can be reduced. Moreover, the above effect can be obtained simply by adjusting the gap between the surface of the counter electrode at each position of the electrode plate and the fixing device. Therefore, an electrode that can be used for manufacturing electrolytic metal foil with less variation in thickness can be provided with a relatively simple configuration.

[0023] Further features and advantages of the present invention will become clearer through the following description of exemplary and non-limiting embodiments, with reference to the drawings.

[0024] Schematic cross-sectional view of the metal foil manufacturing apparatus of the embodiment Schematic perspective view of the metal foil manufacturing apparatus Schematic cross-sectional view of the area where the first electrode and the second electrode face each other Schematic cross-sectional view of the second electrode with the fixing device removed Schematic front view of the fixing device Schematic cross-sectional view of the area where the first electrode and the second electrode face each other (partially enlarged view of Figure 3) Schematic plan view of the fixing device of the first embodiment Schematic cross-sectional view of the fixing device of the first embodiment Schematic plan view of the fixing device of the second embodiment Schematic cross-sectional view of the fixing device of the second embodiment Pseudo Schematic perspective view of the manufacturing apparatus Schematic diagram showing cell division of electrolytic metal foil generated on a pseudo-cathode Contour diagram showing the weight distribution of electrolytic metal foil when using countersunk screws with cross holes Contour diagram showing the weight distribution of electrolytic metal foil when using countersunk screws with hexagonal holes Contour diagram showing the weight distribution of electrolytic metal foil when using the fixing device of the first embodiment Electron microscope image of the bottom surface of the cross hole when using countersunk screws with cross holes Electron microscope image of the bottom surface of the hexagonal hole when using countersunk screws with hexagonal holes

[0025] An embodiment of the metal foil manufacturing apparatus will be described with reference to the drawings. The metal foil manufacturing apparatus 1 of this embodiment is an apparatus for manufacturing metal foil by electroplating (i.e., manufacturing electrolytic metal foil 9). As shown in Figures 1 and 2, the metal foil manufacturing apparatus 1 comprises an electrolytic cell 2, a first electrode 3, and a second electrode 4.

[0026] The electrolytic cell 2 is a tank for holding the electrolyte 25. The electrolytic cell 2 is formed in a box shape having a bottom portion 21 and side wall portions 22 surrounding the bottom portion 21. The electrolyte 25 is held in this box-shaped electrolytic cell 2 while flowing. In addition, a pair of opposing side wall portions 22 are each provided with shaft support portions 23. A drum-shaped first electrode 3 is rotatably mounted in the electrolytic cell 2 by the shaft support portion 23, and a second electrode 4 is provided so as to face the outer surface of the first electrode 3. The electrolyte 25 in the electrolytic cell 2 also enters the gap between the first electrode 3 and the second electrode 4.

[0027] The first electrode 3 is rotatably mounted in the electrolytic cell 2. The first electrode 3 has a substantially cylindrical drum-shaped electrode 31 and a pair of shaft portions 32 positioned at the rotation axis of opposing end faces of the drum-shaped electrode 31. The first electrode 3 is rotatable relative to the electrolytic cell 2 with the pair of shaft portions 32 each supported by corresponding shaft support portions 23. The first electrode 3 is also rotatable relative to the second electrode 4, which is fixed to the electrolytic cell 2. In this embodiment, the first electrode 3 is the cathode.

[0028] The second electrode 4 is provided in the electrolytic cell 2 so as to face the outer circumferential surface (surface 3a) of the first electrode 3. The second electrode 4 is formed in a substantially arc shape in cross-section so as to face the surface 3a of the drum-shaped first electrode 3. In this embodiment, two second electrodes 4 with a substantially arc shape in cross-section and a central angle of approximately 90° are provided side by side so as to face the lower half surface 3a of the drum-shaped first electrode 3. The second electrode 4 is provided at a distance of, for example, 2 to 30 mm from the surface 3a of the first electrode 3. In this embodiment, the second electrode 4 is the anode, and an insoluble anode can be used.

[0029] By connecting one terminal of the power supply (the negative side of the DC power supply) to the first electrode 3 and the other terminal of the power supply (the positive side of the DC power supply) to the second electrode 4, and applying a voltage while rotating the first electrode 3, an electrolytic metal foil 9 is generated on the surface 3a of the first electrode 3 according to the principle of electroplating. The metal foil manufacturing apparatus 1 of this embodiment can adjust the thickness and particle coarseness (fineness) of the resulting electrolytic metal foil 9 by controlling the magnitude and current density of the current. The generated electrolytic metal foil 9 is transported outside the electrolytic cell 2 and, for example, wound up. The electrolytic metal foil 9 may be a metal foil containing at least one selected from the group consisting of copper, nickel, and iron, and is typically copper foil.

[0030] In this embodiment, the term "electrolytic metal foil 9" is used to mean metal foil manufactured using the principle of electroplating. In other words, in this embodiment, the electrolytic metal foil 9 corresponds to "metal foil".

[0031] Furthermore, focusing on the second electrode 4 which constitutes part of the metal foil manufacturing apparatus 1, in this embodiment, the second electrode 4 corresponds to the "electrode," and the drum-shaped first electrode 3 facing it corresponds to the "counter electrode."

[0032] As shown in Figures 2 and 3, the second electrode 4 is composed of a base body 40, an electrode plate 50 provided on the base body 40, and a fixing device 60 for fixing the base body 40 and the electrode plate 50. In this embodiment, a plurality of strip-shaped electrode plates 50 are provided, and these plurality of electrode plates 50 are fixed on the base body 40 in an arranged state. In addition, each individual electrode plate 50 is fixed on the base body 40 by a plurality of fixing devices 60.

[0033] The base body 40 is a base member that supports the electrode plate 50, and is preferably made of a metallic material. The metallic material constituting the base body 40 may include at least one selected from the group consisting of tantalum, niobium, titanium, hafnium, zirconium, tungsten, bismuth, and antimony. The metallic material constituting the base body 40 preferably includes titanium or a titanium alloy. The thickness of the base body 40 is not particularly limited, but may be, for example, about 10 to 40 mm. The base body 40 has a plurality of fastening holes 41 formed therein for fastening the fastener 60. In addition, as shown in Figure 4, a frustoconical surface 42 is formed around each of the plurality of fastening holes 41. The frustoconical surface 42 is formed in an inverse taper shape, gradually widening in diameter from the fastening hole 41 side toward the first electrode 3 side.

[0034] The electrode plate 50 is a plate-shaped member fixed on the substrate 40 and functions substantially as an anode during electroplating. The electrode plate 50 is made of a metallic material. Preferably, the metallic material constituting the electrode plate 50 includes at least one selected from the group consisting of tantalum, niobium, titanium, hafnium, zirconium, tungsten, bismuth, and antimony. Preferably, the metallic material constituting the electrode plate 50 includes titanium or a titanium alloy. The thickness of the electrode plate 50 is not particularly limited, but may be, for example, about 2 to 20 mm.

[0035] The electrode plate 50 has multiple through holes 51 for inserting the shaft portion 61 of the fixing device 60. The through holes 51 are formed in positions that overlap with the fastening holes 41 when the electrode plate 50 is placed on the base body 40. As shown in Figure 4, the electrode plate 50 of this embodiment has a frustoconical surface 52 around the through holes 51. The frustoconical surface 52 is formed in an inverse taper shape, gradually widening in diameter from the fastening hole 41 side of the base body 40 toward the first electrode 3 side. This frustoconical surface 52 is formed in a shape complementary to the frustoconical surface 42 of the base body 40, and is also formed in a shape complementary to the widened diameter portion 63 of the head 62 of the fixing device 60, which will be described later.

[0036] As shown in Figures 3 and 5, the fastener 60 has a shaft portion 61 and a head portion 62 connected to the upper end of the shaft portion 61. The outer surface of the shaft portion 61 is threaded. The shaft portion 61 passes through the through hole 51 of the electrode plate 50 and enters the fastening hole 41 of the base body 40, and is fastened to the base body 40.

[0037] The head portion 62 is formed to have a larger diameter than the shaft portion 61. Furthermore, the head portion 62 is formed to have a larger diameter than the through hole 51 in the electrode plate 50 through which the shaft portion 61 passes. When the shaft portion 61 is fastened to the base 40, the head portion 62 holds the electrode plate 50 between itself and the base 40.

[0038] The head portion 62 of this embodiment has an enlarged diameter portion 63 that gradually increases in diameter relative to the diameter of the shaft portion 61, and a thickened portion 64 that extends above the enlarged diameter portion 63. The enlarged diameter portion 63 is integrated with the upper part of the shaft portion 61, and the thickened portion 64 is integrated further above the enlarged diameter portion 63.

[0039] The enlarged diameter portion 63 is formed in the shape of a frustoconical pyramid. The enlarged diameter portion 63 has an inverse tapered surface 63a that gradually widens as it moves away from the shaft portion 61 (i.e., toward the upper surface 60a of the fixing device 60). The inverse tapered surface 63a of the enlarged diameter portion 63 is complementary in shape to the frustoconical surface 52 of the electrode plate 50, and with the fixing device 60 fixing the base 40 and the electrode plate 50, the frustoconical surface 52 and the enlarged diameter portion 63 (inverse tapered surface 63a) are in full contact.

[0040] Furthermore, the combination of the shaft portion 61 and the enlarged diameter portion 63 of the head portion 62 (in other words, the portion of the fastener 60 in this embodiment excluding the thickened portion 64) is equivalent to a commonly used "countersunk screw".

[0041] The thickened portion 64 can be considered as a part with increased thickness relative to the head of a commonly used "countersunk screw." As shown in Figure 6, with this thickened portion 64, when the fixing device 60 is fixing the base 40 and the electrode plate 50, the thickened portion 64 protrudes from the surface 50a of the electrode plate 50. As a result, in this embodiment, the gap dimension G1 between the upper surface 60a of the fixing device 60 and the surface 3a of the first electrode 3 is smaller than the gap dimension G2 between the surface 50a of the electrode plate 50 and the surface 3a of the first electrode 3.

[0042] With this configuration, the electrical resistance between the first electrode 3 and the fixture 60 via the electrolyte solution 25 can be made smaller than the electrical resistance between the first electrode 3 and the electrode plate 50 via the electrolyte solution 25. Therefore, the difficulty of current flow at the position of the fixture 60 can be improved. This makes it possible to minimize the difference between the current flowing at the position of the electrode plate 50 and the current flowing at the position of the fixture 60, and as a result, reduces variation in the thickness of the obtained electrolytic metal foil 9.

[0043] The thickness-increased portion 64 of the present embodiment is formed to have a substantially constant thickness, and has a tapered surface 64a that gradually decreases in diameter as it moves away from the enlarged diameter portion 63 (that is, toward the upper surface 60a side of the fixture 60). The tapered surface 64a of the thickness-increased portion 64 smoothly continues to the upper surface 60a and the reverse tapered surface 63a of the enlarged diameter portion 63.

[0044] In the present embodiment, the thickness-increased portion 64 is formed thinner than the enlarged diameter portion 63. The ratio of the thickness T2 of the thickness-increased portion 64 to the thickness T1 of the enlarged diameter portion 63 (T2 / T1) is not particularly limited, but is preferably 1 / 5 to 1 / 2, for example. If the ratio of the thickness T2 of the thickness-increased portion 64 to the thickness T1 of the enlarged diameter portion 63 (T2 / T1) is less than 1 / 5, the significance of the existence of the thickness-increased portion 64 is diminished, and the improvement effect on the difficulty of current flow at the position of the fixture 60 may be limited. Conversely, if the ratio of the thickness T2 of the thickness-increased portion 64 to the thickness T1 of the enlarged diameter portion 63 (T2 / T1) exceeds 1 / 2, there is a possibility that excessive current easily flows at the position of the fixture 60. By setting the ratio of the thickness T2 of the thickness-increased portion 64 to the thickness T1 of the enlarged diameter portion 63 (T2 / T1) to 1 / 5 to 1 / 2, the electrical resistance between the first electrode 3 and the fixture 60 can be appropriately reduced, and the difference between the current flowing at the position of the electrode plate 50 and the current flowing at the position of the fixture 60 can be minimized. Therefore, variation in the thickness of the obtained electrolytic metal foil 9 can be reduced as much as possible.

[0045] The ratio of the thickness T2 of the thickness-increased portion 64 to the thickness T1 of the enlarged diameter portion 63 (T2 / T1) is more preferably 1 / 5 to 2 / 5, further preferably 9 / 40 to 1 / 3, and even more preferably 9 / 40 to 3 / 10.

[0046] Furthermore, the ratio (H / D) of the protrusion height H (see Fig. 6) of the head 62 protruding from the surface 50a of the electrode plate 50 to the diameter D of the head 62 (see Figs. 7 to 10) is not particularly limited, but is preferably 1 / 20 to 1 / 5, for example. If the ratio (H / D) of the protrusion height H of the head 62 protruding from the surface 50a of the electrode plate 50 to the diameter D of the head 62 is less than 1 / 20, the improvement effect on the difficulty of current flow at the position of the fixture 60 may be limited. Conversely, if the ratio (H / D) of the protrusion height H of the head 62 protruding from the surface 50a of the electrode plate 50 to the diameter D of the head 62 exceeds 1 / 5, excessive current may easily flow at the position of the fixture 60. By setting the ratio (H / D) of the protrusion height H of the head 62 protruding from the surface 50a of the electrode plate 50 to the diameter D of the head 62 to 1 / 20 to 1 / 5, the electrical resistance between the first electrode 3 and the fixture 60 can be appropriately reduced, and the difference between the current flowing through the position of the electrode plate 50 and the current flowing through the position of the fixture 60 can be minimized. Therefore, variation in the thickness of the obtained electrolytic metal foil 9 can be reduced as much as possible.

[0047] The ratio (H / D) of the protrusion height H of the head 62 protruding from the surface 50a of the electrode plate 50 to the diameter D of the head 62 is more preferably 1 / 20 to 1 / 8, further preferably 3 / 40 to 1 / 8, and even more preferably 3 / 40 to 1 / 10.

[0048] The head 62 also serves as a portion to be operated by a fixing tool (for example, a screwdriver, a wrench, etc.). As shown in Figs. 7 to 10, a locked hole 66 locked by the fixing tool is formed on the upper surface 60a of the fixture 60 while being recessed downward. The fixture 60 can be fastened to the base body 40 by operating the fixing tool in a state where the tip end of the fixing tool is locked in the locked hole 66.

[0049] In this embodiment, a catalyst layer 68 is provided on the upper surface of the head 62 (see Figures 8 and 10). The catalyst layer 68 is also provided on the inner surface (bottom and side) of the locking hole 66. The catalyst layer 68 may contain at least one material selected from the group consisting of platinum, palladium, ruthenium, rhodium, iridium, osmium, titanium, and tin. The catalyst layer 68 can be formed, for example, by applying a processing solution containing these materials from the upper surface of the head 62.

[0050] The locking hole 66 formed in the fixing device 60 can take on various shapes, as long as it is a shape that can be operated with a fixing tool. Typical plan view shapes of the locking hole 66 include, for example, a cross shape as shown in Figures 7 and 8, and a regular hexagon shape as shown in Figures 9 and 10. The former first embodiment of the fixing device 60 is applicable when a Phillips screwdriver is used as the fixing tool, and the latter second embodiment of the fixing device 60 is applicable when a hex wrench is used as the fixing tool.

[0051] The plan view shape of the locking hole 66 is preferably a regular hexagon. By adopting such a shape, it is possible to ensure a sufficiently large opening width for the locking hole 66 formed in the head 62 of the fixing device 60. The ratio of the minimum opening width W of the locking hole 66 to the depth E of the locking hole 66 (W / E) is not particularly limited, but is preferably 1 / 2 or more. The minimum opening width W is the smallest opening width when the locking hole 66 has multiple opening widths that differ depending on the position. By setting the ratio of the minimum opening width W of the locking hole 66 to the depth E of the locking hole 66 (W / E) to 1 / 2 or more, it is possible to ensure a larger opening width for the locking hole 66.

[0052] By ensuring a large opening width for the locking holes 66, when the processing solution containing the catalyst metal is applied from the upper surface of the head 62, the processing solution can sufficiently penetrate into the interior of the locking holes 66. As a result, the catalyst layer 68 can be properly formed not only on the upper surface of the head 62 but also on the inner surfaces (bottom and sides) of the locking holes 66. Therefore, from this point of view as well, the difference between the current flowing through the electrode plate 50 and the current flowing through the fixing device 60 can be minimized, and as a result, variations in the thickness of the resulting electrolytic metal foil 9 can be reduced.

[0053] The ratio of the minimum opening width W of the locking hole 66 to the depth E of the locking hole 66 (W / E) is more preferably 2 / 3 or more, even more preferably 1 / 1 or more, and even more preferably 6 / 5 or more. There is no particular upper limit to the ratio of the minimum opening width W of the locking hole 66 to the depth E of the locking hole 66 (W / E), but in practice it is, for example, 5 / 2 or less.

[0054] Three types of pseudo-anodes 104 were created using Phillips-head countersunk screws, hexagonal-head countersunk screws, and the first type of fixing device 60 shown in Figures 7 and 8. A pseudo-manufacturing apparatus 101 incorporating these was created for each type, as shown in Figure 11. This pseudo-manufacturing apparatus 101 has a structure in which opposing pseudo-cathodes 103 and pseudo-anodes 104 are fixed via spacers 107. The pseudo-anode 104 also has a pseudo-substrate 104A, a pseudo-electrode plate 104B, and a pseudo-fixing device 104C. These were immersed in a pool of electrolyte, and a voltage was applied (with feedback control to keep the current value constant) to generate electrolytic metal foil 9 on the surface of the pseudo-cathode 103 on the pseudo-anode 104 side (see Figure 12). The test conditions were as follows. • Electrolyte: 200 g / L CuSO4 + 150 g / L H2SO4 • Temperature: 50°C • Current: 20 A • Electrolysis time: 10 minutes

[0055] The electrolytic metal foil 9 deposited on the pseudo-cathode 103 was divided and cut into multiple standardized metal foil pieces (30 pieces in total, arranged in 5 rows and 6 columns in the illustrated example) as shown in Figure 12. The portion indicated by the dashed line in Figure 12 is the portion facing the pseudo-electrode plate 104B. The size of each metal foil piece was set to 4 cm² (20 mm × 20 mm). The weight of each metal foil piece was measured, and the thickness distribution of the electrolytic metal foil 9 was estimated from its weight distribution. The results are shown in Figures 13 to 15. Figure 13 shows the results when using Phillips head countersunk screws, Figure 14 shows the results when using hexagonal head countersunk screws, and Figure 15 shows the results when using the fixing device 60 of the first embodiment.

[0056] As shown in Figure 13, when Phillips-head countersunk screws were used, the metal foil pieces at positions 2B, 4B-5B, 2D, and 4D-5D were heavier than the others, while the metal foil piece at position 3C was lighter than the surrounding area. This suggests that a thickness peak appears at positions 2B, 4B-5B, 2D, and 4D-5D, and a deep valley (a portion with thinner thickness than the surrounding area) occurs at position 3C. The position of cell 3C corresponds to the position where the pseudo-fixing device 104C (in this example, a Phillips-head countersunk screw) is fastened to the opposing pseudo-anode 104. Thus, when Phillips-head countersunk screws are used, a relatively large recess occurs, particularly at the position of the countersunk screw, and the overall thickness of the electrolytic metal foil 9 is suggested to be non-uniform. Statistical analysis revealed a standard deviation of 13.4 mg and a coefficient of variation of 12.0%.

[0057] As shown in Figure 14, when hexagonal socket countersunk screws were used, the metal foil pieces at positions 1B-4B, 1C-2C, and 1D-4D were slightly heavier than the others, while the metal foil pieces at positions 3C-5C were slightly lighter than the surrounding areas. This suggests that a relatively gentle thickness peak appears at positions 1B-4B, 1C-2C, and 1D-4D, while a valley (a thinner area compared to the surrounding area) occurs at positions 3C-5C. The position of cell 3C corresponds to the position where the pseudo-fixing device 104C (hexagonal socket countersunk screw in this example) is fastened to the opposing pseudo-anode 104. Thus, although a depression occurred in the region including the position of the countersunk screw when hexagonal socket countersunk screws were used, it was suggested that the thickness of the electrolytic metal foil 9 was somewhat more uniform overall compared to when Phillips socket countersunk screws were used. The standard deviation was 11.8 mg and the coefficient of variation was 8.0%, which was also supported by the results of statistical analysis.

[0058] As shown in Figure 15, when the fixing device 60 of the first embodiment was used, there was no significant difference in the weight of each metal foil piece over a wide range of cells 1B to 5B, 1C to 5C, and 1D to 5D. This suggests that a gentle thickness peak occurs over a wide range of cells 1B to 5B, 1C to 5C, and 1D to 5D. At the position of cell 3C corresponding to the position where the pseudo-fixing device 104C (fixing device 6 of the first embodiment in this example) is fastened on the opposing pseudo-anode 104, a slight valley (a part with a thinner thickness compared to the surrounding area) occurs, but it is suggested to be very shallow. Thus, when the fixing device 60 of the first embodiment is used, it is suggested that the thickness of the electrolytic metal foil 9 is made uniform over a wide area including the position of the fixing device 60. The standard deviation was 7.0 mg and the coefficient of variation was 5.0%, which was also supported by the results of statistical analysis.

[0059] To investigate the effects of different shapes of the locking holes 66, the surface structure of the bottom surface of the locking holes 66 (Phillips head / hexagonal socket) was observed using an electron microscope for both Phillips head countersunk screws and hexagonal socket countersunk screws. When Phillips head countersunk screws were used, relatively large irregularities were observed as shown in Figure 16, suggesting that the countersunk screws and the catalyst layer 68 were not in sufficient contact at the bottom surface of the Phillips head. In contrast, when hexagonal socket countersunk screws were used, the irregularities were less pronounced as shown in Figure 17, suggesting that the catalyst layer 68 was properly formed on the bottom surface of the hexagonal socket as well. In the above example, the slightly more uniform thickness of the electrolytic metal foil 9 when using hexagonal socket countersunk screws compared to when using Phillips head countersunk screws is thought to be due to the formation state of the catalyst layer 68 at the bottom surface of the locking holes 66.

[0060] Furthermore, considering these results together, it can be easily inferred that when the second embodiment of the fixing device 60 shown in Figures 9 and 10 is used, the thickness of the electrolytic metal foil 9 will be made uniform to the same extent as or even better than when the first embodiment of the fixing device 60 is used.

[0061] [Other Embodiments] (1) In the above embodiment, the reinforced portion 64 of the fastener 60 was described as having a tapered surface 64a that gradually decreases in diameter as it moves away from the enlarged portion 63. However, the embodiment is not limited to such a configuration, and for example, the reinforced portion 64 may be formed to have a uniform diameter throughout the entire height direction.

[0062] (2) In the above embodiment, a configuration in which the head 62 of the fastener 60 has an enlarged diameter portion 63 and further has a thickened portion 64 was described as an example. However, the configuration is not limited to such a configuration, and the head 62 does not have to have an enlarged diameter portion 63. In this case, the fastener 60 can be a screw with a larger head 62, such as a round screw, a pan head screw, or a flat head screw. In these configurations, when the fastener 60 is fastened while the head 62 is housed in a counterbore hole formed in the electrode plate 50, the upper part of the head 62 should protrude from the surface 50a of the electrode plate 50. Alternatively, if a thin flat head screw or the like is used as the fastener 60, the entire head 62 may protrude from the surface 50a of the electrode plate 50.

[0063] (3) In the above embodiment, a configuration in which the catalyst layer 68 is provided on the upper surface of the head 62 of the fixing device 60 was described as an example. However, the configuration is not limited to such a configuration, and the catalyst layer 68 does not have to be provided on the upper surface of the head 62.

[0064] (4) In the above embodiment, the locking hole 66 formed in the head 62 of the fastener 60 was described as being formed in a cross shape in plan view to correspond to a Phillips screwdriver as a fastening tool, or in a regular hexagonal shape in plan view to correspond to a hex wrench as a fastening tool. However, the configuration is not limited to such a configuration, and for example, the locking hole 66 may be formed in a straight line in plan view, and a flathead screwdriver may be used as the fastening tool. Alternatively, the locking hole 66 may be formed in other regular polygonal shapes in plan view (for example, an equilateral triangle, a square, a regular pentagon, and a regular octagon, etc.), and a wrench with the corresponding cross-sectional shape may be used as the fastening tool.

[0065] (5) The configurations disclosed in each of the above-described embodiments (including the above-described embodiments and other embodiments; the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as this does not cause a conflict. With respect to other configurations, the embodiments disclosed herein are illustrative in all respects and can be modified as appropriate without departing from the spirit of this disclosure.

[0066] 1 Metal foil manufacturing apparatus 2 Electrolytic cell 3 First electrode (counter electrode) 3a Surface 4 Second electrode (electrode) 9 Electrolytic metal foil (metal foil) 25 Electrolyte 40 Substrate 50 Electrode plate 50a Surface 60 Fixing device 60a Top surface 61 Shaft portion 62 Head portion 63 Enlarged diameter portion 64 Thickened portion 66 Locking hole 68 Catalyst layer G1 Gap dimension between the top surface of the fixing device and the surface of the first electrode G2 Gap dimension between the surface of the electrode plate and the surface of the first electrode D Diameter of the head H Protrusion height of the head from the surface of the electrode plate T1 Thickness of the enlarged diameter portion T2 Thickness of the thickened portion E Depth of the locking hole W Minimum opening width of the locking hole

Claims

1. A metal foil manufacturing apparatus for manufacturing metal foil by electroplating, comprising: an electrolytic cell for holding an electrolyte; a drum-shaped first electrode rotatably mounted in the electrolytic cell; and a second electrode provided in the electrolytic cell so as to face the outer circumferential surface of the first electrode, wherein the second electrode includes a base, an electrode plate provided on the base, and a fixing device for fixing the base and the electrode plate, and the gap dimension between the upper surface of the fixing device and the surface of the first electrode is smaller than the gap dimension between the surface of the electrode plate and the surface of the first electrode.

2. The metal foil manufacturing apparatus according to claim 1, wherein the fixing device has a shaft portion that penetrates the electrode plate and is fastened to the base body, and a head portion connected to the upper end of the shaft portion and pressing down on the electrode plate, and the ratio of the height of the head portion protruding from the surface of the electrode plate to the diameter of the head portion is 1 / 20 to 1 / 5.

3. The metal foil manufacturing apparatus according to claim 1, wherein the fixing device has a head that is operated by a fixing tool, and a shaft that extends downward from the head, penetrates the electrode plate, and is fastened to the base, the head has an enlarged diameter portion that gradually increases in diameter relative to the diameter of the shaft, and a thickened portion that extends above the enlarged diameter portion, the electrode plate has a frustoconical surface with a shape complementary to the enlarged diameter portion around a through hole through which the shaft penetrates, and the frustoconical surface and the enlarged diameter portion are in contact with each other when the fixing device is fixed to the base and the electrode plate, and the thickened portion protrudes from the surface of the electrode plate.

4. The metal foil manufacturing apparatus according to claim 3, wherein the ratio of the thickness of the thickened portion to the thickness of the enlarged portion is 1 / 5 to 1 / 2.

5. The metal foil manufacturing apparatus according to any one of claims 1 to 4, wherein the fixing device has a head formed with a locking hole into which a fixing tool is locked, a catalyst layer is provided on the upper surface of the head, and the ratio of the minimum opening width of the locking hole to the depth of the locking hole is 1 / 2 or more.

6. The metal foil manufacturing apparatus according to claim 5, wherein the locking hole is formed in a regular polygonal shape in plan view.

7. An electrode for use in the manufacture of electrolytic metal foil, comprising a substrate, an electrode plate provided on the substrate, and a fixing device for fixing the substrate and the electrode plate, wherein the electrode is positioned opposite a rotatably mounted drum-shaped counter electrode, and the gap between the upper surface of the fixing device and the surface of the counter electrode is smaller than the gap between the surface of the electrode plate and the surface of the counter electrode.

Images