0001 Japanese Patent Application No. 2000-19125(P), filed Jan. 27, 2000, is hereby incorporated by reference in its entirety. 0002 1. Technical Field 0003 The present invention relates to high-density mounting, and more particularly, preferred embodiments relate to a manufacturing method and a plating apparatus for a film carrier tape that uses an elongated flexible substrate. 0004 2. Related Art 0005 Mounting a semiconductor chip on a film carrier is conventionally known as one of the high-density mounting methods. After a semiconductor chip is mounted on a film carrier, an area surrounding the semiconductor chip in the film carrier is punched out to form a TAB (tape automated bonding) package, which is widely used for, for example, drivers for driving liquid crystal panels and the like. 0006 FIG. 4 shows a configuration of a conventional film carrier tape. As shown in the figure, a film carrier tape 1 is formed from an elongated flexible substrate 2. Holes and the like are punched out in the elongated substrate 2, and then wiring patterns are formed thereon. The elongated substrate 2 is formed from a polyimide material and has sprocket holes on both sides thereof (formed in areas a) continuously formed along the longitudinal direction. Sprockets are provided in the transfer path and engage the sprocket holes to enable transfer of the elongated substrate 2 in a transfer direction (in the direction of an arrow in the figure). 0007 Film carriers 3 are punched out from the elongated substrate 2. For this purpose, the elongated substrate 2 defines punch-out regions 4 each corresponding to the shape of the film carrier 3. The punch-out regions 4 are provided in plurality at equal intervals along the transfer path of the elongated substrate 2. A device hole 5 having a sufficient size to contain a semiconductor chip and an input terminal hole 6 adjacent to the device hole 5 are punched out within the punch-out region 4. 0008 Wiring patterns 7 (a forming region therefor is shown in the figure) composed of a copper material are formed between the device hole 5 and the input terminal hole 6 in the number corresponding to the number of terminals of the semiconductor chip. One end of the wiring patterns protrude from one edge of the device hole 5 as inner leads 9 (a forming region therefor is shown in the figure) to establish conduction with the terminals of the semiconductor chip. On the opposite side of the inner leads 9 in the wiring patterns 7, the wiring patterns 7 are led out across the input terminal hole 6. The portions of the wiring patterns 7 that extend across the input terminal hole 6 define input terminals 8 that are to be connected to terminals formed on an external substrate. 0009 Wiring patterns 7 are led out from the device hole 5 on the opposite side of the area where the input terminal hole 6 is formed in the number corresponding to the number of terminals of the semiconductor chip. Output terminals 10 are formed on tips of the wiring patterns 7 for contact with another external substrate. 0010 The film carrier tape 1 is made in the following manner. First, holes such as the device holes 5 and the input terminal holes 6 are punched out in the elongated substrate 2. Then a copper foil is adhered to the elongated substrate 2 with an adhesive, and the wiring patterns 7 and the like are formed by exposure and etching. After the wiring patterns 7, the input terminals 8 and the inner leads 9 are formed, solder resist for protecting the wiring patterns 7 is coated on the wiring patterns 7. Then the film carrier tape 1 is placed in a tin plating bath to plate surfaces of the input terminals 8 and the inner leads 9. 0011 FIG. 6 shows a structure of a plating apparatus for plating tin on the film carrier tape 1. A plating apparatus 11 shown in the figure has a plating bath 12. A plurality of follower-side sprockets 13 are provided on the inside of the plating bath 12, and driver-side sprockets 14 are provided before and the after the plating bath 12. With the plating bath 12 having the structure described above, the driver-side sprockets 14 are driven to successively dip the film carrier tape 1 in plating liquid 15 in the plating bath 12, such that surfaces of the input terminals 8 and the inner leads 9 are plated. For the plating process, electroless plating (i.e., chemical plating) is conducted in order to obtain a uniform film thickness. 0012 After the plating process is completed and the film carrier tape 1 is completed, semiconductor chips are positioned within the respective device holes 5, and gold bumps (i.e., connection terminals) provided on the semiconductor chips and the inner leads 9 are subject to a thermocompression bonding such that they are bonded together through a eutectic reaction.

Summary 0013 One embodiment relates to a method for manufacturing a film carrier tape in which a wiring pattern is formed on a flexible substrate. The method includes dipping the film carrier tape in a first temperature plating liquid to form a plated layer in an exposed portion of the wiring pattern by a substitution reaction. Then the film carrier tape is dipped in a second temperature plating liquid having a higher temperature than the first temperature plating liquid, to increase the thickness of the plated layer. 0014 Another embodiment relates to a method for manufacturing a film carrier tape in which a wiring pattern is formed on an elongated flexible substrate. The method includes transferring the film carrier tape in a longitudinal direction thereof and dipping the film carrier tape in a first temperature plating liquid to form a plated layer in an exposed portion of the wiring pattern by a substitution reaction. Then, the method includes dipping the film carrier tape in a second temperature plating liquid to increase the thickness of the plated layer, wherein the second temperature plating liquid has a higher temperature than the first temperature plating liquid. In one aspect of certain embodiments, the plated layer comprises tin. 0015 Another embodiment relates to a plating apparatus including a first plating bath containing a plating liquid at a first temperature level and a second plating bath containing a plating liquid at a second temperature level that is higher than the first temperature level. The plating apparatus also includes a transfer path for a film carrier tape in which a wiring pattern is formed on an elongated flexible substrate wherein the transfer path passes through the first plating bath and the second plating bath. 0016 Another embodiment relates to a plating apparatus comprising means for delivering a film carrier tape to a first plating bath at a first temperature along a transfer path, and means for delivering the film carrier tape along the transfer path to a second plating bath at a second temperature that is higher than the first temperature, wherein the first plating bath and the second plating bath have the same composition.

BRIEF DESCRIPTION OF THE DRAWINGS 0017 Embodiments of the invention are described with reference to the accompanying drawings which, for illustrative purposes, are schematic and not necessarily drawn to scale. 0018 FIG. 1 is an explanatory view for describing steps of manufacturing a film carrier tape using a plating apparatus in accordance with one embodiment of the present invention. 0019 FIG. 2 is an explanatory view of one form of a film carrier tape that is processed in the plating apparatus in accordance with an embodiment of the present invention. 0020 FIG. 3 is an expanded view of a main portion taken along lines B-B of FIG. 2. 0021 FIG. 4 is an expanded view of one form of a conventional film carrier tape. 0022 FIG. 5 is an expanded view of a main portion taken along lines B-B of FIG. 4. 0023 FIG. 6 is an explanatory view for describing a conventional structure of a plating apparatus for plating a film carrier tape with tin.

DETAILED DESCRIPTION 0024 In the plating process described above with reference to FIGS. 4-6, the deposition amount per unit time is relatively small. The plating liquid is normally heated to a temperature that does not decompose the plating liquid. However, troubles may occur in the wiring patterns composed of the copper foil when the film carrier tape is subject to a plating process with the plating liquid temperature being raised, although the substitution reaction is improved and the deposition rate is increased. (For example, when the film carrier tape is dipped in the plating liquid at temperatures of 65-70 C. for 3-4 minutes, a plating thickness of about 0.5-0.8 m is obtained.) 0025 FIG. 5 shows an enlarged cross-sectional view of a main area taken along lines A-A of FIG. 4, including wiring pattern 7 attached by adhesive 17 to elongated substrate 2. As shown in the figure, hollowed-out portions 18 are formed in the wiring patterns 7 at an end section of the solder resist 16 that is formed on the wiring patterns 7 or at a base section of the input terminals 8 where the substitution reaction is accelerated several times more than other parts. (It is noted that, although a plated layer 19 is also formed at the hollowed-out portions 18 by the substitution reaction, the plated layer 19 does not cohere to but is separated from the hollowed-out portions 18.) 0026 When the hollowed-out portions 18 are created in the wiring patterns 7, the resistance value of the wiring patterns 7 may increase. Also, when an external force is applied to the wiring patterns 7, the hollowed-out portions 18 may act as cracks and break the wiring patterns 7. 0027 It is empirically known that the magnitude of the hollowed-out portions 18 is reduced when impurities that may be present at an end section of the solder resist 16 formed on the wiring patterns 7 or at a base section of the input terminals 8 are removed. However, even when a washing step is provided before the plating step, the problem described above is not completely removed because it is difficult to completely remove the impurities, and the hollowed-out portions 18 still remain. Moreover, a new problem occurs in that the washing step increases the number of manufacturing steps. 0028 It is an object of preferred embodiments of the present invention to provide a manufacturing method and a plating apparatus for film carrier tapes, in which the plating process does not cause hollowed-out portions in a copper foil at end sections of the solder resist or of the adhesive, and the troubles such as an increased resistance value, breakage of wires and the like are inhibited. 0029 Certain embodiments of the present invention have been made based on discoveries that dipping a film carrier tape in plating liquids of different temperatures can change deposition rates, prevent the generation of hollowed-out portions in the copper foil, and form a plated layer having a sufficient film thickness. 0030 For example, a method for manufacturing a film carrier tape in accordance with one embodiment pertains to a method for manufacturing a film carrier tape in which a wiring pattern is formed on a flexible substrate. The method is characterized in that the film carrier tape is dipped in a lower temperature plating liquid to form a plated layer in an exposed portion of the wiring pattern by a substitution reaction, and then the film carrier tape is dipped in a higher temperature plating liquid to increase the thickness of the plated layer. According to the method for manufacturing a film carrier tape set forth in claim 1, the film carrier tape is first dipped in a plating liquid at a lower temperature. As exposed portions of the wiring pattern contact the plating liquid, the wiring patterns are dissolved into the plating liquid, and a eutectic reaction occurs with the plating liquid to thereby form a plated layer on surfaces of the wiring patterns. In this step, the deposition rate per unit time in the plating liquid is small and the substitution reaction is minimal because the plating liquid is set to a lower temperature. As a result, the substitution reaction is suppressed in corner sections of the exposed portions of the wiring patterns, in other words, in areas of the wiring patterns that are located at end sections of a coating member that covers the wiring patterns. Accordingly, the substitution reaction takes place at a rate similar to those in the other areas of the wiring patterns, and a plated layer preferably having a uniform thickness is formed on the exposed portions of the wiring patterns. 0031 After the plated layer having a uniform thickness is formed on the exposed portions of the wiring patterns, the film carrier tape is dipped in a plating liquid set at a higher temperature. In the plating liquid at the higher temperature, the deposition amount per unit time is greater. Accordingly, the plating material may newly deposit in the thickness direction of the plated layer through pinholes in the plated layer formed by the plating liquid set at the lower temperature level, and the thickness of the plated layer increases. When the plated layer reaches a predetermined thickness (which is normally controlled by the dipping time), the film carrier tape is pulled out from the plating liquid set at the higher temperature level. In this manner, by dipping the film carrier tape in the plating liquids that are set at different temperatures, a plated layer preferably having a uniform thickness is formed on the exposed portions of the wiring patterns. As a result, the formation of hollowed-out portions is inhibited in corner sections of the exposed portions of the wiring patterns, and an increase in the resistance value of the wiring patterns and breakage of the wiring patterns can be prevented. 0032 Also, a method for manufacturing a film carrier tape in accordance with another embodiment pertains to a method for manufacturing a film carrier tape in which a wiring pattern is formed on an elongated flexible substrate. The method is characterized in that the film carrier tape is transferred in a longitudinal direction thereof, the film carrier tape is dipped in a lower temperature plating liquid to form a plated layer in an exposed portion of the wiring pattern by a substitution reaction, and then the film carrier tape is dipped in a higher temperature plating liquid to increase the thickness of the plated layer. This method for manufacturing a film carrier tape provides an effect in that the film carrier tape can be continuously brought in the lower temperature plating liquid and the higher temperature plating liquid, in addition to the effects described above in connection with the embodiment described in the immediately preceding paragraph. Accordingly, an effective plating process can be performed for wiring patterns that are continuously formed along the elongated substrate. 0033 In another aspect of certain embodiments, the exposed portion of a film tape defines an input terminal or an inner lead. Input terminals protruding from an edge of an input terminal hole or inner leads protruding from an edge of a device hole for containing a semiconductor chip can be plated to provide erosion protections on the input terminals or the inner leads. 0034 In another aspect of certain embodiments, the plated layer is composed of tin. The tin and gold may undergo a eutectic reaction to achieve a sufficient bonding strength. Accordingly, the inner leads achieve a sufficient bonding strength with portions of a semiconductor chip, such as, for example, connection terminals thereof that are generally plated with gold, and the bonding reliability is improved. Also, it goes without saying that the tin plating can resist a variety of organic acids. 0035 In another aspect of certain embodiments, the lower temperature plating liquid is set at a temperature of about 10-40 C. and the higher temperature plating liquid is set at a temperature of about 65-70 C. A plated layer composed of fine deposition particles is formed on an exposed surface in the lower temperature plating liquid. Furthermore, in the higher temperature plating liquid, particles having large grain sizes may be deposited above the plated layer formed in the lower temperature plating liquid, and the plated layer can be formed to a predetermined thickness in a short time. 0036 Another embodiment relates to a plating apparatus comprising a first plating bath containing a plating liquid with temperatures thereof being set at a lower level, a second plating bath containing a plating liquid with temperatures thereof being set at a higher level, and a transfer path for a film carrier tape in which a wiring pattern is continuously formed on an elongated flexible substrate wherein the transfer path is provided to pass the first plating bath and the second plating bath. As the film carrier tape is transferred along the transfer path, the film carrier tape is first brought in the first plating bath. Since the plating liquid in the first plating bath is set at a lower temperature, the deposition amount is restricted, and a plated layer having a uniform thickness can be formed on exposed portions of the wiring pattern that is formed on the film carrier. After the plated layer is formed on the exposed portions of the wiring pattern, the film carrier tape is brought in the second plating bath. The plating liquid in the second plating bath is set to a higher temperature than that of the plating liquid in the first plating bath, such that a new plated layer can be formed in a short time in an upper layer of the plated layer that is formed on the exposed portions of the wiring pattern. When the plated layer is formed to a predetermined film thickness, the film carrier tape is pulled out from the second plating bath, and transferred to a succeeding stage. In this manner, the first and second plating baths are provided in the transfer path for film carriers, such that a plated layer can be formed on exposed portions of wiring patterns by simply transferring the film carriers. 0037 A manufacturing method and a plating apparatus for film carrier tapes in accordance with preferred embodiments of the present invention are described below in detail with reference to the accompanying drawings. 0038 FIG. 2 shows one configuration of a film carrier tape that is brought in a plating apparatus. As shown in the figure, a film carrier tape 20 is formed from an elongated flexible substrate 22. Device holes and outer lead holes are punched out in the elongated substrate 22, and then wiring patterns are provided around these holes. 0039 The elongated substrate 22 is made of polyimide in the form of a film, and has a plurality of sprocket holes on both sides thereof, (formed in areas a in the) continuously formed at equal intervals along a longitudinal direction of the elongated substrate 22. Sprockets are provided in the transfer path and engage the sprocket holes to enable transfer of the elongated substrate 22 in a transfer direction (in the direction of an arrow in the figure). 0040 The elongated substrate 22 defines a plurality of punch-out regions 26 for film carriers 24 formed at equal intervals along the longitudinal direction. Each of the punch-out regions 26 corresponds to a punch-out shape of each of the film carriers 24. 0041 A device hole 28 having a sufficient size to contain a semiconductor chip and an input terminal hole 30 adjacent to the device hole 28 are provided within each of the punch-out regions 26. Wiring patterns 32 (a region where they are formed is shown in the figure) are formed between the device hole 28 and the input terminal hole 30. One ends of the wiring patterns 32 protrude from one edge of the device hole 28 as input inner leads 34 (a region where they are formed is shown in the figure) to establish connection with connection terminals to be formed on a surface of a semiconductor chip. On the opposite side of the input inner leads 34 in the wiring patterns 32, the wiring patterns 32 are led out across the input terminal hole 30. Areas of the wiring patterns 32 that extend across the input terminal hole 30 define input terminals 36 (a region where they are formed is shown in the figure) that are to be connected to connection terminals formed on an external substrate. 0042 Output inner leads 38 (a region where they are formed is shown in the figure) are formed along an opposite edge of the device hole 28 on the opposite side of the edge where the input inner leads 34 are formed. The output inner leads 38 may also be also formed in the number corresponding to the number of connection terminals of a semiconductor chip. 0043 Wiring patterns 40 (a region where they are formed is shown in the figure) having the output inner leads 38 defining one end sections thereof extend to an opposite side of the area where the input terminal hole 30 is formed. The other end sections of the wiring patterns 40 are plated with solder to define output terminals 42 that are to be connected to another external substrate. 0044 FIG. 1 is an illustration to describe a process for manufacturing a film carrier tape using a plating apparatus in accordance with one embodiment of the present invention. As shown in the figure, a plating apparatus 44 for performing a plating process for the film carrier tape 20 has two plating baths and a transfer path that is set to pass through the two plating baths. 0045 The plating apparatus 44 has a first plating bath 46 and a second plating bath 48. These plating baths may be formed by dividing one container 50 using a partition 52. Vinyl chloride or rubber may preferably be coated on internal surfaces of the first plating bath 46 and the second plating bath 48 in order to prevent corrosion by the plating liquid. The first plating bath 46 and the second plating bath 48 are preferably provided with independent heaters that function as independent temperature controller means. The heaters are operated to control the temperatures of the plating liquids in the plating baths. 0046 A transfer path 54 for transferring the film carrier tape 20 is provided in a manner to pass the plating baths thus constructed. The transfer path 54 preferably has driver-side sprockets 56 that are disposed before and after the container 50, and follower-side sprockets 58 that are disposed on the inside of the container 50, in other words, inside the first plating bath 46 and the second plating bath 48 (and above the partition 52). These sprockets engage the sprocket holes provided on the elongated substrate 22 on both sides in the width direction thereof such that the film carrier tape 20 can be transferred along locations where the sprockets are disposed. 0047 The plural follower-side sprockets 58 are preferably alternately disposed in the plating baths so that they are disposed up, down, up, down and so on, in order to increase the area of the film carrier tape 20 that is dipped in plating liquid 60. The plating liquid 60 is preferably a solution for electroless tin plating. The inner leads and outer leads composed of copper may be dipped in the solution to plate their surfaces with tin. A follower-side sprocket 58 is also provided over the top portion of the partition 52 such that the follower-side sprocket 58 facilitates the transfer from the first plating bath 46 to the second plating bath 48. The partition 52 defines plating baths containing portions of the plating liquid 60 having different temperatures. Therefore, the partition 52 may preferably be formed with a heat-insulation material such that the heat is not conducted from one to the other. 0048 Furthermore, since the first plating bath 46 is used to form only a thin plated layer on the exposed portions of the wiring patterns 32 on the film carrier tape 20, a few of the follower-side sprockets 58 (three of them in FIG. 1) are provided therein, and the volume of the plating bath is small. On the other hand, the second plating bath 48 is used to form a thick plated layer of the same material on an upper surface of the plated layer formed in the first plating bath 46. Therefore, the number of the follower-side sprockets is greater (eleven of them in the figure), and the volume of the plating bath 48 is greater than that of the first plating bath 46. 0049 One example of a plating process is conducted for the film carrier tape 20 using the plating apparatus 44 in the following manner. 0050 The same plating liquid 60 is filled in the first plating bath 46 and the second plating bath 48, and the heaters that are provided in the respective plating baths are operated to set the plating liquid 60 at predetermined temperatures, respectively. The temperature of the plating liquid 60 in the first plating bath 46 is lower than the temperature of the plating liquid 60 in the second plating bath 48. The temperatures of the plating liquid 60 in the first plating bath 46 and the second plating bath 48 are independently determined in view of factors, such as, for example, the length of the film carrier tape 20 that is dipped in the plating liquid 60, the transfer speed, and the like. Various conditions were considered and it was discovered that good results can be obtained when the plating liquid 60 in the first plating bath 46 is set at temperatures of 10-40 C. and the plating liquid 60 in the second plating bath 48 is set at temperatures of 65-70 C. 0051 After filling the plating baths with the plating liquid 60 and setting the temperatures of the plating liquid 60, the film carrier tape 20 is transferred along the transfer path 44. The film carrier tape 20 is first brought in the first plating bath 46 and dipped in the plating liquid 60 whose temperature is set at a lower level. Portions for the input inner leads 34, the input terminals 36 and the output inner leads 38 (hereafter referred to as lead sections) in the wiring patterns of the film carrier tape 20 are exposed. When the exposed portions are dipped in the plating liquid 60 in the first plating bath 46, a substitution reaction takes place on their surfaces. As a result, copper is dissolved from the lead sections and tin is deposited on the surfaces of the lead sections to form a plated layer. As described above, the plating liquid 60 is set to a lower temperature, the deposition amount is small and the substitution reaction is minimal. As a result, the plated layer formed in the first plating bath 46 is substantially thin as compared to a predetermined thickness of the plated layer. (When the dipping lasts 20 seconds, a layer having a film thickness of about 0.1 m is formed.) 0052 FIG. 3 shows an enlarged view of a main portion taken along lines B-B in FIG. 2. The input inner leads 34 protrude from the input terminal hole 30 formed in the elongated substrate 22. Base sections of the input inner leads 34 define wiring patterns 32 that are adhered to the elongated substrate 22 by an adhesive 62. In the first plating bath 46, the substitution reaction is suppressed at the base sections of the input terminals 36 and the substitution reaction becomes similar to those at the other portions, such that a plated layer having a uniform thickness is formed on the input terminals 36. In other words, in the first plating bath 46, the substitution reaction rate is low, and the substitution reaction at the bases of the input terminals does not become excessive. Therefore the occurrence of hollowed-out portions at the base sections of the input terminals 36 is inhibited. Referring to FIG. 3, solder resist 64 is coated over the wiring patterns 32. In this case, hollowed-out portions are not formed and a plated layer having a uniform thickness in a manner similar to the other regions is formed at end sections (border sections) of the solder resist 64. 0053 After the plated layer having a uniform thickness is formed on the exposed portions in the first plating bath 46, the film carrier tape 20 is brought in the second plating bath 48. As described above, the plating liquid 60 in the second plating bath 48 is set to a higher temperature than that of the plating liquid 60 in the first plating bath 46, and thus the deposition amount per unit time is greater. The same plating material is newly deposited through pinholes in a plated layer formed in the first plating bath 46, such that a plated layer 66 is formed. Since the plated layer that has already been formed in the first plating bath 46 is present as a lower layer when the plated layer 66 is formed, the base sections of the input terminals 36 or the end sections (border sections) of the solder resist 46 are prevented from forming hollowed-out portions. When the film carrier tape 20 comes closer to a last stage of the transfer path 54 in the second plating bath 48, the plated layer 66 reaches the predetermined thickness. Then, the film carrier tape 20 is pulled out from the second plating bath 48. (The plated layer formed in the second plating bath 48 reaches, for example, a thickness of about 0.5-0.8 m, and the dipping time in the second plating bath 48 is about 3-4 minutes.) In the film carrier tape 20 manufactured through the steps described above, the plated layer 66 formed on the input terminals 36 and the like shown in the figure has a uniform thickness. As a result, problems such as an increase in the wiring resistance value, breakage of wirings and the like can be inhibited. 0054 In the manner described above, the plating apparatus 44 is disposed in the transfer path 54 for the film carrier tape 20. As a result, a plating process can be continuously performed by simply transferring the film carrier tape 20, and therefore the process efficiency is improved. 0055 In the embodiment described above, the single container 50 is divided by the partition 52 to form the first plating bath 46 and the second plating bath 48. However, the present invention is not limited to this embodiment. For example, these plating baths can be formed from independent baths, and the transfer path may be set to pass through the baths. 0056 As described above, one method embodiment for manufacturing a film carrier tape pertains to a method in which a wiring pattern is formed on a flexible substrate. The film carrier tape is dipped in a lower temperature plating liquid to form a plated layer in an exposed portion of the wiring pattern by a substitution reaction, and then the film carrier tape is dipped in a higher temperature plating liquid to increase the thickness of the plated layer. As a result, hollowed-out portions are not formed at the exposed portion of the wiring pattern, and problems such as an increase in the wiring resistance value, breakage of the wirings and the like can be prevented. 0057 Also, in an aspect of certain embodiments, the elongated substrate is transferred along its longitudinal direction and is continuously processed, with the result that an effective plating process can be performed. 0058 Furthermore, a plating apparatus according to certain embodiments has a first plating bath containing a plating liquid with temperatures thereof being set at a lower level, a second plating bath containing a plating liquid with temperatures thereof being set at a higher level, and a transfer path for a film carrier tape in which wiring patterns are continuously formed on an elongated flexible substrate, wherein the transfer path is provided to pass the first plating bath and the second plating bath. As a result, a uniform plated layer is formed on exposed portions of the wiring patterns in the film carriers. 0059 While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. For example, embodiments may include variations in the temperature and time for carrying out the plating operations and a variety of plating chemicals used may be used in addition to those described above.