Plating bath, plating device, and electroplating method

Abstract

A plating tank of one embodiment of the present disclosure is a plating tank for electroplating a substrate for a flexible printed wiring board, and includes: a container configured so that the substrate is inserted in the vertical direction as a cathode; an anode disposed in the container so as to face the substrate; a supply portion configured to supply a plating solution to the container from the side or the top of the container; and a discharge portion configured to discharge the plating solution below the substrate in the container. The distance between the outer surfaces of the two opposing side portions of the container in the direction perpendicular to the substrate is 100 mm or less.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a plating bath, a plating device, and a plating method. This application claims priority based on Japanese Patent Application No. 2020-091691 filed on May 26, 2020, and all the recitations described in the above Japanese Patent Application are incorporated by reference. BACKGROUND

[0002] A plating bath described in Patent Literature 1 is configured in such a manner that a plating solution is supplied from the lower side or the side of a container to the inside of the container and stored, and at the same time, the supplied plating solution is caused to overflow from the upper end of the container (hereinafter, sometimes referred to as "overflow method"), while the above-mentioned substrate is electroplated (see Japanese Patent Application Publication No. 2004-143478).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2004-143478 SUMMARY

[0006] One embodiment of the present disclosure relates to a plating bath for electroplating a substrate for a flexible printed wiring board, comprising: a container configured in such a manner that the above-mentioned substrate is inserted as a cathode in the vertical direction; an anode disposed in the above-mentioned container in such a manner as to oppose the above-mentioned substrate which is inserted; a supply portion capable of supplying a plating solution to the inside of the above-mentioned container from the side or the upper side of the above-mentioned container; and a discharge portion disposed below the above-mentioned substrate with respect to the above-mentioned container, capable of discharging the above-mentioned plating solution, wherein the distance between the outer surfaces of the two opposing side surface portions of the above-mentioned container in the direction perpendicular to the above-mentioned substrate is 100 mm or less.

[0007] Another embodiment of the present disclosure relates to a plating device comprising: a plating bath for electroplating a substrate for a flexible printed wiring board; a storage portion capable of storing a plating solution supplied to the above-mentioned plating bath; and a liquid delivery portion capable of delivering the above-mentioned plating solution from the above-mentioned storage portion to the above-mentioned plating bath, wherein the above-mentioned plating bath comprises: a container configured in such a manner that the above-mentioned substrate is inserted as a cathode in the vertical direction; an anode disposed in the above-mentioned container in such a manner as to oppose the above-mentioned substrate which is inserted; a supply portion capable of supplying a plating solution to the inside of the above-mentioned container from the side or the upper side of the above-mentioned container; and a discharge portion disposed below the above-mentioned substrate with respect to the above-mentioned container, capable of discharging the above-mentioned plating solution, wherein the distance between the outer surfaces of the two opposing side surface portions of the above-mentioned container in the direction perpendicular to the above-mentioned substrate is 100 mm or less, the above-mentioned storage portion is capable of storing the above-mentioned plating solution discharged from the above-mentioned discharge portion, and the above-mentioned liquid delivery portion is capable of delivering the above-mentioned plating solution from the above-mentioned storage portion to the above-mentioned supply portion.

[0008] Another aspect of the present disclosure relates to a plating method for plating a substrate for a flexible printed wiring board, including a plating step of plating the substrate using a plating bath, the plating bath including a container configured to have the substrate as a cathode and to have the substrate inserted in a vertical direction, an anode disposed in the container in opposition to the inserted substrate, a supply portion configured to supply a plating solution into the container from a side or an upper side of the container, and a discharge portion configured to discharge the supplied plating solution from a lower side of the container than the substrate, wherein a distance between outer surfaces of two opposing side portions of the container in a direction perpendicular to the substrate is 100 mm or less, and wherein, in the plating step, the substrate and the anode are electrified while the plating solution is supplied into the container from the supply portion and the supplied plating solution is discharged from the discharge portion, thereby plating the substrate. BRIEF DESCRIPTION OF DRAWINGS

[0009] [ Figure 1 ] Figure 1 FIG. 1 is a schematic cross-sectional view showing a plating bath according to an embodiment of the present disclosure.

[0010] [ Figure 2 ] Figure 2 FIG. 2 is a schematic side view showing a configuration of a plating device according to an embodiment of the present disclosure.

[0011] [ Figure 3 ] Figure 3 FIG. 3 is a graph showing a result of simulation of a relationship between a distance between a substrate and an anode (inter-electrode distance) and a thickness of a plated body, in a case where a deflection of the substrate is set to 0 mm.

[0012] [ Figure 4 ] Figure 4 FIG. 4 is a graph showing a result of simulation of a relationship between a distance between a substrate and an anode (inter-electrode distance) and a thickness of a plated body, in a case where a deflection of the substrate is set to 3 mm.

[0013] [ Figure 5 ] Figure 5 FIG. 5 is a graph showing a result of simulation of a relationship between a distance between a substrate and an anode (inter-electrode distance) and a standard deviation of a thickness of a plated body, in a case where a deflection of the substrate is set to 3 mm. DETAILED DESCRIPTION

[0014] In the field of electronic devices, flexible printed wiring boards are used in many cases. A flexible printed wiring board is obtained, for example, by forming a plated body (plated layer) on an outer surface of a conductive base layer (thin conductive layer having a thickness of about several nm) of a substrate for a printed wiring board having a base film and the conductive base layer laminated on a surface of the base film, and further patterning the conductive base layer and the plated body.

[0015] Generally, a plating device for forming the plated body described above has a plating bath having a container that stores a plating solution, an anode that is disposed opposite the substrate and is immersed in the plating solution, and a mechanism that applies a voltage to the substrate and the anode.

[0016] As such a plating bath, for example, the plating bath described in the above-described Patent Document 1 is proposed.

[0017] [Problems to be Solved by the Disclosure]

[0018] Here, in the electroplating described above, it is desirable to reduce the plating usage amount, and it is also desirable to save space.

[0019] However, in the plating bath described in the above-described Patent Document 1, the smaller the size of the container in the direction perpendicular to the substrate becomes, the more likely it is that the thickness of the plated body formed will deviate.

[0020] Therefore, an object is to provide a plating bath, a plating device, and an electroplating method that can form a plated body that has a suppressed deviation in thickness on a substrate for a flexible printed wiring board in a manner that uses a relatively small amount of plating and saves space.

[0021] [Effects of the Disclosure]

[0022] The plating bath, the plating device, and the electroplating method according to one embodiment of the present disclosure can form a plated body that has a suppressed deviation in thickness on a substrate for a flexible printed wiring board in a manner that uses a relatively small amount of plating and saves space.

[0023] [Explanation of Embodiments of the Disclosure]

[0024] First, an embodiment of the present disclosure is described.

[0025] The plating bath for a printed wiring board according to one embodiment of the present disclosure is a plating bath for electroplating a substrate for a flexible printed wiring board, and includes a container that has the substrate as a cathode and is configured so that the substrate is inserted in the vertical direction, an anode that is disposed in the container so as to be opposite the inserted substrate, a supply portion that can supply a plating solution to the container from the side or the top of the container, and a discharge portion that is disposed below the substrate in the container and can discharge the plating solution, and in the direction perpendicular to the substrate, the distance between the outer surfaces of the two opposing side portions of the container is 100 mm or less.

[0026] Here, the present inventors have made intensive studies, and as a result, have obtained the following findings. That is, as a means for achieving reduction in plating usage amount in electroplating and space saving, it is considered to reduce the size of the container of the plating bath. More specifically, it is considered to reduce the distance between the outer surfaces of the two side surface portions opposite to each other of the above container in the direction perpendicular to the substrate. However, the present inventors have found that, as shown in the following examples, in the case where the plating solution is supplied to the container of the plating bath in the overflow manner as described in the above Patent Document 1, when the above distance is reduced, the thickness of the plated body formed on the substrate can possibly be deviated. The reason why the thickness is deviated in this way is not certain, but it is presumed that, for example, under the overflow manner, irregular flow such as convection of the plating solution is easily generated inside the above container, and due to this irregular flow, the flexible substrate which is originally more easily bent is bent, and the thickness of the plated body formed on the substrate is deviated due to this bending. Further, the smaller the above distance is, the smaller the space where the plating solution can flow becomes, and thus it is difficult to eliminate the irregularity of the flow, and as a result, the above deviation further becomes larger.

[0027] On the contrary, by providing the plating bath with the above supply portion and discharge portion, and by making the above distance of the above container within the above range, the plating solution can be sequentially supplied into the above container, stored inside the above container, and discharged from the above discharge portion while not overflowing from the upper end of the above container, and electroplating can be performed on the above substrate. In this way, by sequentially discharging the plating solution from inside the container, the plating solution can exist in the container in a state where the irregularity (degree of irregularity) of the flow of the plating solution is smaller compared to the above overflow manner. Due to this, even if the above distance is a small distance such as 100 mm or less, the deviation of the thickness of the plated body can be suppressed. Further, by reducing the above distance, the capacity of the above container becomes smaller, and thus the plating usage amount can be reduced, and space saving can be achieved. Therefore, the plating bath can form a plated body on a substrate for a flexible printed wiring board in a manner where the plating usage amount is relatively small and space saving is achieved, and can suppress the deviation of the thickness of the formed plated body.

[0028] The above supply portion can supply the above plating solution into the above container from the upper side of the above container.

[0029] By making the above supply portion supply the plating solution into the above container from the upper side of the above container, the irregularity of the flow of the plating solution inside the above container can be further reduced. Due to this, the deviation of the thickness of the plated body formed on the above substrate can be easily suppressed.

[0030] Another aspect of the present disclosure relates to a plating device including: a plating bath for electroplating a substrate for a flexible printed wiring board; a storage portion capable of storing a plating solution supplied to the plating bath; and a solution delivery portion capable of delivering the plating solution from the storage portion to the plating bath, the plating bath including: a container configured such that the substrate is inserted in the container along a vertical direction with the substrate serving as a cathode; an anode disposed in the container so as to face the inserted substrate; a supply portion capable of supplying the plating solution to the container from a side or an upper side of the container; and a discharge portion disposed below the substrate with respect to the container and capable of discharging the plating solution, a distance between outer surfaces of two opposing side portions of the container in a direction perpendicular to the substrate being 100 mm or less, the storage portion being capable of storing the plating solution discharged from the discharge portion, and the solution delivery portion being capable of delivering the plating solution from the storage portion to the supply portion.

[0031] The plating device includes the plating bath described above, and thus, as described above, is capable of forming a plated body on the substrate with a relatively small amount of plating and in a space-saving manner, and is capable of suppressing a variation in thickness of the formed plated body.

[0032] Another aspect of the present disclosure relates to a plating method for electroplating a substrate for a flexible printed wiring board, including an electroplating step of electroplating the substrate using a plating bath, the plating bath including: a container configured such that the substrate is inserted in the container along a vertical direction with the substrate serving as a cathode; an anode disposed in the container so as to face the inserted substrate; a supply portion capable of supplying a plating solution to the container from a side or an upper side of the container; and a discharge portion disposed below the substrate with respect to the container and capable of discharging the plating solution, a distance between outer surfaces of two opposing side portions of the container in a direction perpendicular to the substrate being 100 mm or less, and in the electroplating step, the substrate and the anode are electrified while the plating solution is supplied from the supply portion to the container and the supplied plating solution is discharged from the discharge portion, thereby electroplating the substrate.

[0033] The plating method uses the plating bath described above, and thus, as described above, is capable of forming a plated body on the substrate for a flexible printed wiring board with a relatively small amount of plating and in a space-saving manner, the plated body having a suppressed variation in thickness.

[0034] [Details of Embodiments of the Present Disclosure]

[0035] Hereinafter, a plating bath, a plating device, and a plating method according to an embodiment of the present disclosure will be described with reference to appropriate drawings.

[0036] [First Embodiment]

[0037] <Plating Bath>

[0038] Figure 1 The plating bath 1 is a plating bath for electroplating a substrate X for a flexible wiring board. The plating bath 1 has a vessel 3 (refer to Figure 2 ) configured in such a manner that the substrate X is inserted in the vessel 3 along the vertical direction with the substrate X serving as a cathode; two anodes 5 disposed in the vessel 3 opposite the substrate X inserted; a supply portion 7 capable of supplying a plating solution Y2 into the vessel 3 from the side or the upper side (in Figure 1 , the upper side) of the vessel 3; and a discharge portion 9 disposed below the substrate X inserted in the vessel 3 and capable of discharging the plating solution Y2. The plating bath 1 further has a shielding film 11 in contact with the surface of each anode 5 on the substrate X side and disposed opposite the substrate X. The plating bath 1 further has a mechanism (also referred to as "voltage application mechanism", not shown) for applying a voltage to the substrate X and the two anodes 5 inserted, respectively.

[0039] The plating bath 1 is used, for example, in such a state that the outer surfaces of the two conductive base layers (also referred to as seed layers) of the printed substrate X having a base film and the surfaces laminated on both sides of the base film are disposed opposite one anode 5, respectively. The plating bath 1 causes metal ions dissolved in the plating solution Y2 to be reduced on the outer surfaces of the respective conductive base layers constituting the cathode by supplying electric current from the voltage application mechanism to the substrate X and the anodes 5, respectively, so that plating bodies can be formed on the outer surfaces of the respective seed layers, respectively.

[0040] (Vessel)

[0041] The vessel 3 has the substrate X inserted therein, supplies and discharges the plating solution Y2 without overflowing the plating solution Y2 used for electroplating the substrate X inserted, and is capable of storing the plating solution Y2 with the substrate X immersed therein during a period required for electroplating the substrate X.

[0042] In Figure 1 , the vessel 3 is formed in such a manner that a cross-sectional shape (longitudinal cross section, refer to Figure 1 ) obtained by cutting along the vertical direction is rectangular, a cross-sectional shape (transverse cross section) obtained by cutting along the horizontal direction (direction perpendicular to the substrate X, left-right direction of Figure 1 ) is rectangular, and the upper side is open.

[0043] The substrate X is inserted in the vessel 3. The plating solution Y2 is supplied from the supply portion 7 into the vessel 3. The discharge portion 9 for discharging the plating solution Y2 in the vessel 3 is provided at the bottom surface portion 3b of the vessel 3. The two anodes 5 are disposed in the vessel 3 opposite the surfaces on both sides of the substrate X inserted, respectively.

[0044] The container 3 is formed in such a way that the distance (first distance) L between the outer surfaces of the two opposite side portions 3a of the container 3 in the direction perpendicular to the substrate X is 100 mm or less.

[0045] Here, as described above and as will be said later, in a conventional plating bath where the plating solution is supplied in an overflow manner, the smaller the aforementioned distance L becomes, the more likely the thickness of the plating formed on the substrate X will deviate.

[0046] However, in this embodiment, by viewing the container from above or the side (in...) Figure 1 Electroplating is performed simultaneously by supplying plating solution Y2 into container 3 (from the top) and discharging the plating solution Y2 from container 3 through discharge section 9 without overflowing. Even when the distance L is reduced to, for example, 100 mm or less, deviations in the thickness of the plating body can be suppressed. Furthermore, electroplating can be performed with less plating material than before and in a space-saving manner. In addition, the smaller the distance L is than 100 mm, the greater the advantage of this plating tank 1.

[0047] The upper limit of the aforementioned distance L is 100 mm, more preferably 80 mm, and even more preferably 60 mm. The lower limit of the aforementioned distance L is not particularly limited; for example, it can be appropriately set in a way that allows electroplating to proceed without causing a short circuit. For example, the lower limit of the aforementioned distance L is preferably 30 mm, and even more preferably 40 mm. If the distance L exceeds the aforementioned upper limit, an excess of plating solution Y2 compared to the amount required for electroplating may be wasted and supplied to the container 3. On the other hand, if the distance L does not meet the aforementioned lower limit, a short circuit may occur, and the amount of plating solution Y2 required for electroplating may not be present in the container 3.

[0048] There is no particular limitation on the thickness (wall thickness) of container 3; it can be set appropriately. For example, the thickness of container 3 can be set to approximately 10 mm.

[0049] The spacing between the substrate X and each anode 5, i.e., the shortest distance connecting the substrate X and each anode 5 (the second distance, hereinafter also referred to as the "inter-electrode spacing"), is not particularly limited and can be appropriately set according to the aforementioned distance L of the container, the thickness of the substrate X, the thickness of the anode 5, the thickness of the shielding film 11, etc. For example, generally, the smaller the aforementioned distance L becomes, the smaller the aforementioned inter-electrode spacing can become. When this aspect is taken into consideration, the smaller the aforementioned inter-electrode spacing, the greater the advantage of the plating tank 1. For example, as the upper limit of the aforementioned inter-electrode spacing, 50 mm is preferred, and more preferably 45 mm is preferred. As the lower limit of the aforementioned inter-electrode spacing, 30 mm is preferred, and more preferably 35 mm is preferred. If the aforementioned inter-electrode spacing exceeds the aforementioned upper limit, an excess of plating solution Y2 compared to the amount of plating solution Y2 required for electroplating may be wastedly supplied into the container 3. On the other hand, if the aforementioned inter-electrode spacing does not meet the aforementioned lower limit, a short circuit may occur, and the amount of plating solution Y2 required for electroplating may not be present in the container 3.

[0050] (anode)

[0051] Each anode 5 has a constant thickness and is formed in a plate shape. Furthermore, in a plan view, i.e., viewed in a direction perpendicular to the substrate X, each anode 5 is formed as a rectangle. Each anode 5 can be, for example, a soluble anode with metals such as copper, nickel, or silver as its main component, or an insoluble anode using platinum or iridium-coated titanium. However, an insoluble anode is preferred, as it easily prevents shape changes of the anode itself and achieves uniform thickness of the plating formed on the substrate X. Here, in this disclosure, "main component" refers to the component with the highest content, for example, a component that accounts for 50% or more by mass in the forming material.

[0052] There is no particular limitation on the thickness of anode 5; it can be set appropriately. For example, the thickness of anode 5 can be set to approximately 5 mm.

[0053] (Supply Department)

[0054] exist Figure 1 In this container, the supply unit 7 is positioned above the container 3. The supply unit 7 is configured to dispense plating solution Y2 downwards into the container 3. Examples of such a supply unit 7 include, for instance, a known sprayer or similar device with multiple nozzles along the extending direction of the substrate X capable of spraying plating solution Y2 into the container 3. The speed at which plating solution Y2 is supplied from the supply unit 7 can be appropriately set such that the substrate X is completely immersed in the plating solution Y2 within the container 3 without the plating solution Y2 overflowing from the upper end of the container 3. By supplying plating solution Y2 from above the container 3 via the supply unit 7, the irregularity of the flow of plating solution Y2 within the container 3 can be further reduced. This makes it easier to suppress variations in the thickness of the plating formed on the substrate X.

[0055] (Discharge section)

[0056] As described above, the discharge portion 9 is provided at the bottom surface portion 3b of the container 3. As the discharge portion 9, for example, a discharge port capable of discharging the plating solution Y2 from the inside of the container 3, a known discharge mechanism capable of adjusting the discharge amount, and the like can be cited. The speed of discharging the plating solution Y2 from the discharge portion 9 can be appropriately set in a manner that the substrate X is completely immersed in the plating solution Y2 in the container 3 and the plating solution Y2 does not overflow from the upper end portion of the container 3.

[0057] (shielding film)

[0058] Each of the shielding films 11 is a film for achieving uniformization of the current density, thereby achieving uniformization of the film thickness of the plating body. As the shielding film 11, a known shielding film can be used. The thickness of the shielding film 11 is not particularly limited and can be appropriately set. The thickness of the shielding film 11 can be set to about 1 mm, for example.

[0059] (plating solution)

[0060] As the plating solution Y2, there is no particular limitation and a known plating solution containing copper sulfate, copper pyrophosphate, or the like can be used, for example.

[0061] <Advantages>

[0062] By providing the plating bath 1 with the above-described supply portion 7 and the discharge portion 9 and setting the above-described distance L of the container 3 within the above-described range, the plating solution Y2 can be stored in the container 3 without overflowing from the upper end of the container 3, the plating solution Y2 can be sequentially supplied into the container 3 to store the plating solution in the container 3 in a manner that the substrate X is immersed in the plating solution Y2, and the plating solution can be moved from the supply portion 7 to the discharge portion 9 by gravity, thereby electroplating the substrate X while discharging the plating solution from the discharge portion 9. In this way, by electroplating without overflowing the plating solution, even if the distance L is a small distance such as 100 mm or less, the thickness deviation of the plating body can be suppressed. In addition, by setting the distance L to 100 mm or less, the plating usage amount in electroplating can be reduced, and space can be saved.

[0063] Therefore, the plating bath 1 can form a plating body on the substrate X for a flexible printed wiring board in a manner that the plating usage amount is relatively small and space is saved, and the thickness deviation of the formed plating body can be suppressed.

[0064] [Second Embodiment]

[0065] <Plating method>

[0066] Next, a plating method using the plating bath 1 will be described. The plating method is a method of electroplating the above-described substrate X for a flexible printed wiring board, and includes a plating step of electroplating the above-described substrate X using the above-described plating bath 1.

[0067] (plating step)

[0068] In the above plating process, the plating solution Y2 is supplied from the supply portion 7 of the plating bath 1 into the container 3, and the supplied plating solution Y2 is discharged from the discharge portion 9, while the substrate X and each anode 5 are electrified, thereby performing electroplating.

[0069] Specifically, in the above plating process, the substrate X is inserted into the container 3, the plating solution Y2 is supplied from the supply portion 7 into the container 3, and the supplied plating solution Y2 is discharged from the above discharge portion 9, thereby becoming a state in which the plating solution Y2 is stored in the container 3 in a manner that the plating solution Y2 does not overflow and the substrate X is entirely immersed in the plating solution Y2. In this state, the above substrate X and the above anode 5 are electrified by the above voltage application device. In the case where the electroplating method is performed in the manufacture of a flexible printed wiring board using a subtractive method, in the above plating process, the substrate X on which a resist pattern is not formed on a conductive base layer is used. On the other hand, in the case where the electroplating method is performed in the manufacture of a flexible printed wiring board using a semi-additive method, in the above plating process, the substrate X on which a resist pattern is formed on a conductive base layer is used.

[0070] As a main component of the plated body formed in the above plating process, copper, nickel, silver, and the like can be listed. Among them, copper is preferable in that it is excellent in conductivity and easily forms a plated body of a uniform thickness at relatively low cost.

[0071] In the above plating process, as an upper limit of the distance between the substrate X and each anode 5, 50 mm is preferable, and 45 mm is more preferable, as described above. As a lower limit of the above interval, 30 mm is preferable, and 35 mm is more preferable.

[0072] <Advantages>

[0073] The electroplating method uses the above plating bath 1, and thus, as described above, can form a plated body in which the thickness deviation is suppressed on the substrate X for a flexible printed wiring board in a manner that the plating usage amount is relatively small and the space is saved.

[0074] [Third Embodiment]

[0075] <Plating Device>

[0076] Next, a plating device provided with the above plating bath 1 of the first embodiment will be described. The plating device is configured in such a manner that a plurality of processes including an electroplating process (step) can be performed on one substrate X in the above plating bath 1.

[0077] In the above plating process, the substrate X is inserted into the container 3, the plating solution Y2 is supplied from the supply portion 7 into the container 3, and the supplied plating solution Y2 is discharged from the above discharge portion 9, thereby becoming a state in which the plating solution Y2 is stored in the container 3 in a manner that the plating solution Y2 does not overflow and the substrate X is entirely immersed in the plating solution Y2. In this state, the above substrate X and the above anode 5 are electrified by the above voltage application device. In the case where the electroplating method is performed in the manufacture of a flexible printed wiring board using a subtractive method, in the above plating process, the substrate X on which a resist pattern is not formed on a conductive base layer is used. On the other hand, in the case where the electroplating method is performed in the manufacture of a flexible printed wiring board using a semi-additive method, in the above plating process, the substrate X on which a resist pattern is formed on a conductive base layer is used. Figure 2In the plating device 20, the plating tank 1, the first storage portion 21, the second storage portion 23, and the third storage portion 25 capable of storing the liquid discharged from the discharge portion 9 of the container 3 of the plating tank 1, the first valve 27 configured to be capable of switching the storage site of the liquid discharged from the discharge portion 9 of the container 3 to the first storage portion 21, the second storage portion 23, and the third storage portion 25, and the second valve 29 for delivering any one of the liquids Y delivered from the first storage portion 21, the second storage portion 23, and the third storage portion 25 to the supply portion 7 are provided.

[0078] The plating device 20 further includes the first pipe 31 configured to form a liquid delivery path for delivering the liquid from the discharge portion 9 of the container 3 to the first valve 27, the second pipe 33 configured to form a liquid delivery path for delivering the liquid from the first valve 27 to the first storage portion 21, the third pipe 35 configured to form a liquid delivery path for delivering the liquid from the first valve 27 to the second storage portion 23, and the fourth pipe 37 configured to form a liquid delivery path for delivering the liquid from the first valve 27 to the third storage portion 25.

[0079] The plating device 20 further includes the fifth pipe 41 configured to form a liquid delivery path for delivering the liquid from the first storage portion 21 to the second valve 29, the sixth pipe 43 configured to form a liquid delivery path for delivering the liquid from the second storage portion 23 to the second valve 29, and the seventh pipe 45 configured to form a liquid delivery path for delivering the liquid from the third storage portion 25 to the second valve 29.

[0080] The plating device 20 further includes the first liquid delivery portion 51 provided to the fifth pipe 41 and capable of delivering the liquid from the first storage portion 21 to the second valve 29 by a driving force, the second liquid delivery portion 53 provided to the sixth pipe 43 and capable of delivering the liquid from the second storage portion 23 to the second valve 29 by a driving force, and the third liquid delivery portion 55 provided to the seventh pipe 45 and capable of delivering the liquid from the third storage portion 25 to the second valve 29 by a driving force.

[0081] The plating device 20 further includes the eighth pipe 47 configured to form a liquid delivery path for delivering the liquid from the second valve 29 to the supply portion 7.

[0082] (Plating tank)

[0083] The constitution of the plating bath 1 is as described in detail in the first embodiment described above, and thus detailed description thereof is omitted. In the present embodiment, the plating bath 1 is used not only for plating processing but also for other processing. That is, in the container 3 of the plating bath 1, not only the plating solution Y2 but also other liquids (here, the degreasing solution Yl and the cleaning solution Y3) are supplied from the supply section 7. More specifically, any one of the degreasing solution Yl, the plating solution Y2, and the cleaning solution Y3 is switched from the supply section 7 and delivered into the container 3.

[0084] (First storage section)

[0085] The degreasing solution Yl described above is stored in the first storage section 21, for example. The first storage section 21 is disposed at a position at which the degreasing solution Yl from the discharge section 9 in the container 3 can be delivered. The first storage section 21 is disposed below the container 3, for example. The degreasing solution Yl stored in the first storage section 21 is delivered to the second valve 29 via the fifth pipe 41 by the driving force of the first liquid delivery section 51, further delivered from the second valve 29 to the supply section 7, and supplied into the container 3 from the supply section 7. The degreasing solution Yl supplied into the container 3 is delivered to the first valve 27 from the discharge section 9 of the container 3 via the first pipe 31, further delivered from the first valve 27 to the first storage section 21 (returned) via the second pipe 33. In this way, the degreasing solution Yl circulates between the first storage section 21 and the container 3.

[0086] (Second storage section)

[0087] The plating solution Y2 described above is stored in the second storage section 23, for example. The second storage section 23 is disposed at a position at which the plating solution Y2 from the discharge section 9 in the container 3 can be delivered. The second storage section 23 is disposed below the container 3, for example. The plating solution Y2 stored in the second storage section 23 is delivered to the second valve 29 via the sixth pipe 43 by the driving force of the second liquid delivery section 53, further delivered from the second valve 29 to the supply section 7, and supplied into the container 3 from the supply section 7. The plating solution Y2 supplied into the container 3 is delivered to the first valve 27 from the discharge section 9 of the container 3 via the first pipe 31, further delivered from the first valve 27 to the second storage section 23 (returned) via the third pipe 35. In this way, the plating solution Y2 circulates between the second storage section 23 and the container 3.

[0088] (Third storage section)

[0089] The cleaning solution Y3 is stored in the third storage portion 25, for example. The third storage portion 25 is disposed at a position at which the cleaning solution Y3 discharged from the discharge portion 9 in the container 3 can be supplied. The third storage portion 25 is disposed below the container 3, for example. The cleaning solution Y3 stored in the third storage portion 25 is supplied to the second valve 29 via the seventh pipe 45 by a driving force of the third liquid supply portion 55, further supplied from the second valve 29 to the supply portion 7, and supplied from the supply portion 7 into the container 3. The cleaning solution Y3 supplied into the container 3 is supplied from the discharge portion 9 of the container 3 to the first valve 27 via the first pipe 31, further supplied from the first valve 27 to the third storage portion 23 (return) via the fourth pipe 37. In this way, the cleaning solution Y3 is circulated between the third storage portion 23 and the container 3.

[0090] (First Valve)

[0091] The first valve 27 is a switching valve that can switch a liquid supply path so that one kind of liquid discharged from the container 3 can be supplied to any one of the three storage portions. Specifically, in a case where the degreasing solution Yl discharged from the container 3 is supplied to the first storage portion 21, the first valve 27 is switched so that only the degreasing solution Yl is supplied to the first storage portion 21 and not supplied to the second storage portion 23 and the third storage portion 25. In a case where the plating solution Y2 discharged from the container 3 is supplied to the second storage portion 23, the first valve 27 is switched so that only the plating solution Y2 is supplied to the second storage portion 23 and not supplied to the first storage portion 21 and the third storage portion 25. In a case where the cleaning solution Y3 discharged from the container 3 is supplied to the third storage portion 25, the first valve 27 is switched so that only the cleaning solution Y3 is supplied to the third storage portion 25 and not supplied to the first storage portion 21 and the second storage portion 23. As such a first valve 27, a publicly known four-way switching valve or the like can be cited.

[0092] (Second Valve)

[0093] The second valve 29 is a switching valve capable of switching the liquid delivery path so that the liquid from any one of the above three storage sections can be delivered to the supply section 7. Specifically, in the case where the degreasing liquid Yl is delivered from the first storage section 21 to the supply section 7, the second valve 29 is switched so that only the degreasing liquid Yl from the first storage section 21 is delivered to the supply section 7, and the plating liquid Y2 and the cleaning liquid Y3 from the second storage section 23 and the third storage section 25 are not delivered to the supply section 7. In the case where the plating liquid Y2 is delivered from the second storage section 23 to the supply section 7, the second valve 29 is switched so that only the plating liquid Y2 from the second storage section 23 is delivered to the supply section 7, and the degreasing liquid Yl and the cleaning liquid Y3 from the first storage section 21 and the third storage section 25 are not delivered to the supply section 7. In the case where the cleaning liquid Y3 is delivered from the third storage section 25 to the supply section 7, the second valve 29 is switched so that only the cleaning liquid Y3 from the third storage section 25 is delivered to the supply section 7, and the degreasing liquid Yl and the plating liquid Y2 from the first storage section 21 and the second storage section 23 are not delivered to the supply section 7. As such a second valve 29, a publicly known four-way switching valve or the like can be cited.

[0094] (First to eighth pipes)

[0095] Each of the above first to eighth pipes can use a publicly known pipe, for example.

[0096] (First to third liquid delivery sections)

[0097] As each of the above first to third liquid delivery sections, a publicly known pump capable of delivering a liquid can be used.

[0098] (Degreasing liquid)

[0099] The above degreasing liquid Yl is a liquid for removing a fatty component or the like adhering to the surface of the substrate X. As such a degreasing liquid Yl, a publicly known degreasing liquid can be used.

[0100] (Plating liquid)

[0101] As the above plating liquid Y2, the above plating liquid Y2 can be used.

[0102] (Cleaning liquid)

[0103] The above cleaning liquid Y3 is a liquid for cleaning the substrate X on which a plated body is formed. As such a cleaning liquid Y3, a publicly known cleaning liquid can be used.

[0104] (Processing of substrate using plating device)

[0105] The processing of the substrate X using the plating apparatus 20 (the operation of the plating apparatus 20) will be described. In the present embodiment, for example, the plating apparatus 20 is used to sequentially perform a degreasing process of the substrate X, an electroplating process of the substrate X, and a cleaning process of the substrate X on which a plated body is formed.

[0106] In the above-described degreasing process, first, the substrate X is inserted into the container 3. Next, the degreasing liquid Yl is supplied from the first liquid storage portion 21 to the supply portion 7 via the first liquid feeding portion 51, the fifth pipe 41, the second valve 29, and the eighth pipe 47, and is supplied from the supply portion 7 into the container 3. The supplied degreasing liquid Yl is stored in the container 3 in such a manner that the substrate X is completely immersed in the degreasing liquid Yl, and is discharged from the discharge portion 9 in such a manner that it does not overflow from the upper end of the container 3. The degreasing liquid Yl discharged from the discharge portion 9 is transported to the first liquid storage portion 21 via the first pipe 31, the first valve 27, and the second pipe 33 due to gravity or the like. In this way, the degreasing liquid Yl is circulated between the first liquid storage portion 21 and the container 3. During this circulation, the surface of the substrate X is degreased by contact between the degreasing liquid Yl in the container 3 and the substrate X.

[0107] After the above-described degreasing process, the degreasing liquid Yl in the container 3 is completely discharged to the first liquid storage portion 21. The substrate X in the container 3 is disposed as it is in the container 3. Then, as necessary, the container 3, the first pipe 31, the first valve 27, the second valve 29, and the eighth pipe 47 are appropriately cleaned using a known method.

[0108] In the above-described electroplating process, the substrate X has been inserted into the container 3. Next, the plating liquid Y2 is supplied from the second liquid storage portion 23 to the supply portion 7 via the second liquid feeding portion 53, the sixth pipe 43, the second valve 29, and the eighth pipe 47, and is supplied from the supply portion 7 into the container 3. The supplied plating liquid Y2 is stored in the container 3 in such a manner that the substrate X is completely immersed in the plating liquid Y2, and is discharged from the discharge portion 9 in such a manner that it does not overflow from the upper end of the container 3. The plating liquid Y2 discharged from the discharge portion 9 is transported to the second liquid storage portion 23 via the first pipe 31, the first valve 27, and the third pipe 35 due to gravity or the like. In this way, the plating liquid Y2 is circulated between the second liquid storage portion 23 and the container 3. During this circulation, as described in the first embodiment and the second embodiment described above, the surfaces of both sides of the substrate X in the container 3 are electroplated by applying a voltage to the substrate X and each anode 5, so that a plated body is formed on each of the above-described surfaces.

[0109] After the above plating treatment, the plating solution Y2 in the container 3 is entirely discharged to the second storage section 23. The substrate X (laminate) on which the plated body is formed is disposed in the container 3 as it is. Then, as necessary, the inside of the container 3, the first pipe 31, the first valve 27, the second valve 29, and the eighth pipe 47 are appropriately cleaned by a publicly known method.

[0110] In the above cleaning treatment, the above laminate has been inserted into the container 3. Next, the cleaning solution Y3 is supplied from the third storage section 25 to the supply section 7 through the third liquid feeding section 55 via the seventh pipe 45 and the second valve 29, and is supplied from the supply section 7 into the container 3. The supplied cleaning solution Y3 is stored in the container 3 in such a manner that the substrate X is completely immersed in the cleaning solution Y3, and is discharged from the discharge section 9 in such a manner that it does not overflow from the upper end of the container 3. The cleaning solution Y3 discharged from the discharge section 9 is transported to the third storage section 25 via the first pipe 31, the first valve 27, and the fourth pipe 37 by gravity or the like. In this way, the cleaning solution Y3 is circulated between the third storage section 25 and the container 3. During this circulation, the surface of the above laminate is cleaned by contact of the cleaning solution Y3 in the container 3 with the above laminate.

[0111] In this way, by using the plating apparatus 20, a plurality of treatments can be performed on the substrate X in the container 3 without taking the substrate X out of the container 3. Thus, the apparatus can be miniaturized. In addition, since the above plating bath 1 is used in the above plating treatment, the thickness deviation of the plated body formed on the substrate X can be suppressed.

[0112] <Advantages>

[0113] The plating apparatus 20 is provided with the plating bath 1, and thus, as described above, can form a plated body having a suppressed thickness deviation on the substrate X for a flexible printed wiring board in a manner that uses a relatively small amount of plating and saves space.

[0114] In addition, the plating apparatus 20 can perform a plurality of treatments on the substrate X with the substrate X disposed in the container 3 as it is by switching the liquid supplied to the plating bath 1. Thus, compared with a plating apparatus provided with a plurality of baths for performing a plurality of treatments, the plating apparatus 20 can be miniaturized and can shorten the processing time.

[0115] Further, the plating apparatus 20 can perform a plurality of treatments on the substrate X with the substrate X disposed in the container 3 of the plating bath 1 as it is without taking it out. Thus, the substrate X, which is relatively easy to bend, can be further prevented from being bent during each treatment.

[0116] The plating bath, plating device, and electroplating method according to the embodiments of the present disclosure can form a plated body with suppressed thickness deviation on a substrate for a flexible printed wiring board in a manner that uses less plating solution and saves space, and thus are suitable for manufacturing of high-quality flexible printed wiring boards.

[0117] [Other Embodiments]

[0118] It should be understood that the embodiments of the present disclosure are exemplary in all aspects and are not limiting. The scope of the present invention is not limited to the configurations of the above-described embodiments, but is indicated by the claims, and is intended to include all modifications within the meaning and range equivalent to the claims.

[0119] For example, in the first embodiment described above, the case where the plating bath is provided with a supply portion 7 for supplying the plating solution Y2 into the container 3 from the upper side of the container 3 is described, but in addition thereto, a mode where the plating bath is provided with a supply portion for supplying the plating solution Y2 from the side of the container 3 can be adopted.

[0120] For example, in the first embodiment described above, the case where the plating bath is provided with a discharge portion 9 at the bottom surface portion 3b of the container 3 is described, but in addition thereto, a mode where the plating bath is provided with a discharge portion at the side surface portion 3a of the container 3 below the substrate X can be adopted.

[0121] For example, in the first embodiment described above, the case where the plating bath is provided with two anodes 5 in the container 3 is described, but in addition thereto, a mode where the plating bath is provided with one anode in the container can be adopted. In correspondence thereto, a mode where the plating bath is provided with one shielding film in the container can be adopted. In addition, a mode where the plating bath is not provided with a shielding film can be adopted.

[0122] For example, in the third embodiment described above, the case where the plating device is provided with three storage portions 21, 23, 25 is described, but a mode where the plating device is provided with only one storage portion (i.e., the second storage portion 23) can be adopted, and in addition, a mode where the plating device is provided with four or more storage portions can be adopted. In addition, as the liquid stored in the storage portion other than the storage portion for the plating solution, not only a degreasing solution and a cleaning solution, but also a publicly known liquid for processing the substrate X can be used. In addition, the order in which the plurality of liquids are supplied to the plating bath (the order in which a plurality of processes are performed) is not particularly limited, and can be appropriately set as needed.

[0123] Embodiments

[0124] Hereinafter, the present disclosure will be described more specifically by embodiments, but the present invention is not limited to the following embodiments.

[0125] As a model experiment, the influence of the interval between the substrate and one anode (inter-electrode distance) on the thickness of the plated body formed on the substrate was investigated by simulation using the following method, conditions, and analysis software by changing the degree of flexure of the substrate (substrate flexure and no flexure). Note that the above inter-electrode distance depends on the distance L between the outer surfaces of the two side portions of the container in the direction perpendicular to the substrate. Therefore, in the present experiment, a smaller above inter-electrode distance corresponds to a smaller above distance L.

[0126] <Method / Conditions>

[0127] • Model used: 2D simple model

[0128] As the 2D simple model, a model in which plating concentration does not occur at the both end portions in the horizontal direction of the substrate was designed in order to investigate only the influence of the inter-electrode distance.

[0129] • Length of substrate: 250 mm

[0130] • Flexure of substrate: 0 mm (no flexure), 3 mm (with flexure)

[0131] • Inter-electrode distance: The following 7 levels

[0132] 200 mm, 150 mm, 100 mm, 50 mm, 30 mm, 20 mm, 10 mm

[0133] • Analysis software: Film Thickness Guide

[0134] • Current condition: 2.0 A / dm 2

[0135] • Thickness of plated body (target value): 40 μm

[0136] <Results>

[0137] The results are shown in Figs. Figure 3 , Figure 4 , and Figure 5 . In Figs. Figure 3 and Figure 4 , the center of the substrate is set as x = 0 (origin), the x axis indicates the distance from the origin in the above horizontal direction on the substrate, and the y axis indicates the thickness of the plated body. In Fig. Figure 5 , the x axis indicates the inter-electrode distance, and the y axis indicates the standard deviation of the thickness of the plated body and the deterioration rate (increase rate) of the standard deviation at each inter-electrode distance when the standard deviation at the inter-electrode distance of 200 mm is set as 1.

[0138] As shown in Fig. Figure 3 , it can be seen that even in the case where the substrate is assumed not to be flexed (flexure of 0 mm), the smaller the inter-electrode distance, the smaller the thickness of the plated body. As shown in Figs. Figure 4As shown, it can be seen that, in a case where the substrate is assumed to generate a relatively large deflection (deflection of 3 mm), the inter-electrode distance becomes smaller, and the deviation of the thickness due to the difference in position on the substrate becomes very large. That is, it can be seen that, in a case where the inter-electrode distance is 200 mm or less, the inter-electrode distance becomes smaller, and the deviation of the thickness due to the difference in position on the substrate (deviation of the thickness distribution) becomes larger. From Figure 5 It can be understood that the smaller the distance L, the more significantly the deviation of the thickness distribution increases.

[0139] Thus, it is conjectured that, in a case where the plating solution is supplied from the bottom surface portion of the container of the plating bath in an overflow manner, the thickness of the plating body formed on the substrate can have a large deviation. In contrast, the plating bath shown in the above embodiment can supply the plating solution from the upper portion or the side portion of the container and discharge it from the discharge portion of the bottom surface portion of the container in a manner not to overflow. Thus, it is conjectured that, in a case where the plating bath is used for plating a substrate for a flexible printed wiring board which is relatively easy to deflect, even if the inter-electrode distance is reduced, that is, even if the distance L of the container is reduced (100 mm or less), the deviation of the thickness of the plating body formed on the substrate can be suppressed.

[0140] Explanation of symbols

[0141] 1 plating bath

[0142] 3 container

[0143] 3a side surface portion

[0144] 3b bottom surface portion

[0145] 5 anode

[0146] 7 supply portion

[0147] 9 discharge portion

[0148] 11 shielding film

[0149] 20 plating device

[0150] 21 first storage portion

[0151] 23 second storage portion

[0152] 25 third storage portion

[0153] 27 first valve

[0154] 29 second valve

[0155] 31 first pipe

[0156] 33 second pipe

[0157] 35 third pipe

[0158] 37 4th pipe

[0159] 41 5th pipe

[0160] 43 6th pipe

[0161] 45 7th pipe

[0162] 47 8th pipe

[0163] 51 1st liquid feeding section

[0164] 53 2nd liquid feeding section

[0165] 55 3rd liquid feeding section

[0166] X substrate

[0167] Y liquid

[0168] Y1 degreasing liquid

[0169] Y2 plating liquid

[0170] Y3 cleaning liquid

Claims

1. A plating tank for electroplating a substrate for flexible printed circuit boards, comprising: A container constructed with the substrate as the cathode and the substrate inserted in a vertical direction; The anode is positioned within the container in a manner opposite to the inserted substrate; A supply unit capable of supplying plating solution into the container from the side or top; as well as A discharge section is disposed below the substrate in the container, which allows the plating solution to be discharged without overflowing from the top of the container. In a direction perpendicular to the substrate, the distance between the outer surfaces of two opposite side portions of the container is 30 mm to 100 mm. The distance between the substrate and the anode is more than 30 mm and less than 50 mm.

2. The plating tank according to claim 1, wherein, The supply unit is capable of supplying the plating solution into the container from above.

3. A plating apparatus, comprising: A plating tank used for electroplating substrates for flexible printed circuit boards. A storage unit capable of storing the plating solution supplied to the plating tank; as well as It is capable of transporting the plating solution from the storage section to the plating tank's delivery section. The plating tank includes: A container constructed with the substrate as the cathode and the substrate inserted in a vertical direction; The anode is positioned within the container in a manner opposite to the inserted substrate; A supply unit capable of supplying plating solution into the container from the side or top; and A discharge section is disposed below the substrate in the container, which allows the plating solution to be discharged without overflowing from the top of the container. In a direction perpendicular to the substrate, the distance between the outer surfaces of two opposite side portions of the container is 30 mm to 100 mm. The distance between the substrate and the anode is 30mm to 50mm. The storage section is capable of storing the plating solution discharged from the discharge section. The liquid delivery unit is capable of delivering the plating solution from the storage unit to the supply unit.

4. An electroplating method for electroplating a substrate for a flexible printed circuit board, comprising an electroplating step of electroplating the substrate using a plating bath, wherein... The plating tank has the following features: A container constructed with the substrate as the cathode and the substrate inserted in a vertical direction; The anode is positioned within the container in a manner opposite to the inserted substrate; A supply unit capable of supplying plating solution into the container from the side or top; as well as A discharge section is disposed below the substrate in the container, which allows the plating solution to be discharged without overflowing from the top of the container. In a direction perpendicular to the substrate, the distance between the outer surfaces of two opposite side portions of the container is 30 mm to 100 mm. The distance between the substrate and the anode is 30mm to 50mm. In the electroplating process, electroplating is performed by simultaneously supplying plating solution from the supply section into the container and discharging the supplied plating solution from the discharge section onto the substrate and the anode.

Images