JPH0314911B2 - - Google Patents

Description

[Detailed description of the invention]

B. Purpose of the invention a. Industrial application field The present invention is directed to applying solder, tin, silver, copper, or other metals to plate-like objects such as IC lead frames and printed circuit boards, or objects to be plated such as rod-like objects. This relates to a device for plating the entire surface. b. Prior Art A rasping method is generally used as a conventional means for applying full-surface plating to an object to be plated, such as a plate-like object or a rod-like object as described above. This is, for example, ``Metsukimanial'' (written by Rihei Tomono, published by Ohmsha Co., Ltd. in 1972).
As described on pages 57 to 78 of the issue published on October 25th, a plate-shaped or rod-shaped object to be plated is hung on a rack (jig) that has a hooking part while being in contact with the cathode part. Then, electrolytic treatment is performed in a plating solution. In addition, especially when plating the entire interior of an IC lead frame, plating the exterior after resin molding, or plating the entire surface of a printed circuit board with copper, it is easy to process a large number of sheets by hooking them into one for mass production. Common. c. Problems to be Solved by the Invention When the entire surface of an object to be plated, such as a plate-shaped object or a rod-shaped object, is plated by the above-mentioned conventional rasping method, the following problems arise. (i) Due to the so-called edge phenomenon in Metsuki,
The closer to the side of the object to be plated, the more likely it is to be plated. Therefore, when we look at a large number of objects to be plated that are easily hooked, we can see that the more the objects are hooked toward the sides, the thicker the plating will be. The plating thickness becomes smaller as the thickness increases. Also, when looking at a single object to be plated, the plating thickness is larger toward the side edges, and smaller toward the center, although this is not the same overall difference as described above. Even if a shielding plate is provided between the anode and the anode, this phenomenon still causes a difference in the plating film thickness in the gap between the shielding plate and the anode. This variation in plating thickness is simply unacceptable, especially in IC lead frames and printed circuit boards that require high precision, and often results in rejection. (ii) It is necessary to change the size of the rack and the position and shape of the cathode contact depending on the length, width, etc. of the object to be plated, and it is time consuming to prepare a dedicated rack or contact and replace it. It was. In addition, IC lead frames and printed circuit boards that are to be plated are
It is difficult to automatically rack a large number of sheets easily. Furthermore, the structure of the treatment tank makes it difficult to exchange and stir the liquid, resulting in a low current density, making it impossible or difficult to increase the plating speed. The present invention aims to solve the problems associated with the above-mentioned conventional full surface plating means. In other words, the object of the present invention is to provide a method for full-surface plating that makes the thickness of the plating film uniform on the object to be plated, eliminates the need for a dedicated rack, enables automation of holding the object with a jig, and enables high-speed plating processing. The goal is to provide equipment. B. Arrangement of the Invention a Means for Solving the Problems The entire surface plating device of the present invention has a plating tank 2 containing:
An endless conveying means 4 that can move horizontally inside is provided, and a holding jig 5 capable of holding the object 1 to be plated in a horizontally long vertical shape is continuously provided on the outer periphery of the conveying means 4, and a cathode contact 7 is provided endlessly. Shielding plates 10, 10 are provided movably in the conveying part 6 above the holding jig 5, and have anode openings 9, 9 on both sides of the conveying part 6 at regular intervals in the direction of movement. , parallel anodes 11, 11 are provided outside the respective anode openings 9, 9 on both sides of the object to be plated, and the conveying means 4
, the longitudinal center of the object 1 to be plated is the shielding plate 1
When it comes to the 0, 10 anode opening 9, 9 position,
It is designed to allow intermittent movement that stops for a certain period of time. The above configuration will be explained in more detail. The endless conveyance means 4 is, for example, an endless roller chain type, and is moved horizontally to form a conveyance path 8 by means of foils 12 provided at the front and rear of the plating tank 2 and rotating on a horizontal axis. The conveying means 4 is arranged such that the longitudinal center portion of the object 1 is connected to the shielding plate 1.
When it comes to the 0, 10 anode opening 9, 9 position,
It should be possible to perform intermittent motion that stops for a certain period of time. In addition, the intermittent movement is determined by the time it takes for the object to be plated to pass between the shielding plates 10 and 10, and the time it takes for the object to be plated to pass between the shielding plates 10 and 10, in order to adjust the plating film thickness distribution over the entire surface of the object to be plated to a desired state. To make it possible to appropriately adjust the pause time. The holding jig 5 for the object to be plated 1 has a frame shape capable of holding the object to be plated 1 horizontally and vertically, for example, a semicircular shape when viewed from the front (see Fig. 1), and a dogleg shape when viewed from the side. It has a frame shape in which frame members in the shape of an inverted dogleg are arranged side by side so that the top and bottom are narrow (see FIG. 3), and are continuously provided around the outer periphery of the conveying means 4. The endless cathode contact 7 is, for example, chain-type endless, and is movable together within the transport portion 6 above the holding jig 5. As described above, the shielding plates 10, 10 are arranged in parallel on both sides with the conveyance path 8 in between.
0 and 10, anode openings 9 and 9 are formed at regular intervals along the conveyance direction, that is, along the conveyance path 8. The constant interval between the openings 9, 9 may be made larger than at least the width of the object 1 to be plated. The anodes 11, 11 are provided outside the respective openings 9, 9 of the shielding plates 10, 10 in parallel with both side surfaces of the object 1 to be plated. It may be housed in an anode case or may be shaped like a plate. Furthermore, depending on the type of the object 1 to be plated, the thickness of the plating film may not be required to be so uniform, so the conveyance means 4 may be configured to be capable of continuous movement for that case. In the figure, reference numeral 3 denotes a contact stripping tank, which is placed at the bottom of the plating tank 2 as shown in FIGS. It is a good idea to add a stripping solution that uses some of the ingredients of the plating solution, excluding the above. Further, when the conveying means 4 and the holding jig 5 are returned to the front position of the plating tank 2, the endless cathode contact 7 is moved further forward by the holding jig 5, as shown in FIG. separated from the front wall 13
The liquid is guided to the outside of the plating tank 2 and passed through the peeling tank 3 via the roll 17, and then the rear wall 1
It is desirable to be able to circulate the plating tank 2 from the plating tank 4 to the plating tank 2 again. Reference numerals 15 and 15 indicate liquid drain plates, and reference numerals 16 and 16 indicate circulation pipes for stirring the plating liquid between the shielding plates. b. Function The working state of the present invention is as follows. Electrodes in a plating tank 2 containing a plating solution are energized, and a conveying means 4 capable of intermittent movement is driven to sequentially send short objects 1 to be plated at equal intervals. The object to be plated 1 is transported within a conveying section 6 located above a holding jig 5 provided on the outer periphery of the conveying means 4, and an endless cathode contact 7 that moves together with the holding jig 5.
They are held horizontally and vertically at equal intervals on the top. By the movement of the conveyance means 4, the object to be plated 1 in the conveyance section 6 above the holding jig 5 is conveyed on the horizontal conveyance path 8 from the rear to the front of the plating tank 2. The shaped cathode contact 7 is also moving together with the holding jig 5 while contacting the object 1 to be plated as described above. On both sides of the conveyance path 8 along which the object to be plated 1 moves, there are shielding plates 10 having anode openings 9 at regular intervals.
10, and anodes 11, 11 are provided in parallel on the outside of each anode opening 9, 9. For the object to be plated 1,
A plating film is formed while moving on the conveyance path 8, but when passing between the shielding plates 10, 10, the plating is more likely to break out near the side edges of the object 1 due to the edge phenomenon. The plating film tends to become thick. However, in the present invention, the conveying means 4 is arranged so that the central part of the object to be plated 1 that has been conveyed is connected to the anode opening 9,
When it reaches the position corresponding to 9, it is made to stop for a certain period of time by intermittent movement. Therefore, during the stoppage, the plating is more likely to break out in the central part of the object to be plated 1 at the position corresponding to the anodes 11, 11 than in the part closer to the side edges, contrary to when it passes between the shielding plates 10, 10. It is easy to form a thick plating film. Therefore, while the object 1 to be plated is moving in the plating tank 2 as described above, the anode openings 9, 9
By passing through the plate while stopping for a certain period of time, the plating film is sufficiently repeatedly formed on the central part of the object 1 to be plated. As a result, at the stage when the object 1 to be plated has finished moving in the plating tank 2, the plating film on the object 1 to be plated will have a substantially uniform thickness both in the center and near the side edges. . Furthermore, in the present invention, the anodes 11, 11 are
The openings 9 for anodes on both sides are provided on the outside of the anode openings 9, 9 in parallel with both side surfaces of the object to be plated 1 in the holding jig 5. Therefore, even when the distance between the anodes 11, 11 and the cathode contact 7 is short, the object to be plated and the anodes 11, 11
The shortest distance to the plating object 1 is approximated by the height of each part of the object 1 to be plated. Therefore, the thickness of the plating film in the height direction of the object 1 to be plated is also easily made uniform. In addition, the endless cathode contact 7 and the contact stripping tank 3
If the configuration is as shown in FIGS. 1 and 3 as described above, the cathode contact 7 is placed close to the front of the plating tank 2 during the above-mentioned operating state, and when the conveying means 4 returns, the conveying means 4 It is separated from the plating tank 2 and the holding jig 5, goes out of the plating tank 2, passes through the contact stripping tank 3, and returns to the plating tank 2. By passing through the contact stripping tank 3, the electrodeposited plating on the cathode contact 7 is removed by the electrolytic stripping solution in the stripping tank 3. At this time, only the cathode contact 7 passes through the stripping tank 3, and the conveyance means 4 and holding jig 5 only move within the plating tank 2, so the amount of plating solution taken out and brought in is extremely small. ing. The stripping solution in the stripping tank 3 is a plating solution or an electrolytic stripping solution containing a plating solution as a component. Therefore, even if the plating solution is brought into the stripping tank 3 through the cathode contact 7, the electrolytic stripping solution, which is the same as the plating solution, will not change in quality, and conversely, bringing the stripping solution into the plating tank 2 will not cause any problems. Furthermore, it is no longer necessary to wash the cathode contact 7 with water after electrolytic stripping. c. Example In order to confirm the effects of the present invention, an experiment was conducted under the following conditions using the entire surface plating apparatus shown in FIGS. 1 to 5 as an example. Plating solution 9:1 solder slott KB bath (manufactured by Maxx Schulator, West Germany), radio wave density 5A/dm ² , bath temperature 20C, set film thickness value 7 μm, distance between electrodes 40 to 50 mm, IC to be plated
Lead frame (Dip28 pin 220×45mm, Flat84
(pin 188 x 55 mm), shielding plate length 600 mm, time 3.5 minutes (content stop time 35 seconds, each movement time 52.5 seconds),
Film thickness measuring machine Fluorescent X-ray film thickness measuring machine (manufactured by Seiko)
The film thickness of each part of the object to be plated 1 was measured using a model SFT-158. The table below shows a comparison of those plated under the same conditions using the conventional racking method.

【table】

[Table] As is clear from the above table, when the entire surface is plated according to the present invention, the difference between the maximum film thickness and the minimum film thickness becomes extremely small compared to when the conventional rasping method is used. C. Effects of the Invention As is clear from the above, the entire surface plating device of the present invention has the following effects. a. The thickness of the plating film on the object to be plated can be made uniform. In other words, in the conventional rucking method,
Due to the edge phenomenon, the plating tends to break out closer to the side edges of the plated object, making the film thicker than the center. This variation in plating thickness is particularly acceptable for IC lead frames and printed circuit boards that require high precision. There were many cases where the test was not completed and the test was rejected. However, in the present invention, as described above, shielding plates having anode openings are provided at equal intervals on both sides of the conveyance path in the plating tank, and when the central part of the object to be plated comes to the position corresponding to the openings, , and is transported intermittently so as to stop for a certain period of time. Therefore, plating is likely to occur in the center of the object to be plated, resulting in a plating film thickness similar to that near the side edges. Furthermore, in the present invention, the anodes are provided outside the anode openings on both sides of the conveyance path and parallel to both sides of the object to be plated in the holding jig, so even when the distance between the anode and the cathode is short. The shortest distance between the object to be plated and the anode is approximated at each height of the object to be plated.
Therefore, the thickness of the plating film can be easily made uniform at each position in the height direction of the object to be plated. Therefore, in the present invention, a substantially uniform plating film thickness can be formed over the entire surface of the object to be plated. b. Depending on the length, width, and other shapes of the object to be plated, there is no need to change the size of the rack, the position and shape of the cathode contact, and high-speed plating processing can be performed. In other words, in the conventional racking method, it takes time and effort to prepare special racks and contacts according to the length and width of the object to be plated, and to replace them depending on the object to be plated, resulting in poor workability. . Due to the structure of the plating tank, it was difficult to stir the liquid at high speed, resulting in a low current density. On the other hand, in the present invention, the object to be plated can be thrown into the holding jig which is intermittently moving, and the object to be plated can be automatically engaged and held, regardless of the length, width, etc. of the object to be plated. Furthermore, since the inside of the plating tank can be stirred as a whole parallel to the longitudinal direction (transportation direction) of the objects to be plated, high-speed stirring and high current density are possible, and high-speed plating can be achieved. c In addition, as in the plating device shown in the figure, if only the endless cathode contact is taken out from the rear of the plating tank and circulated through the plating solution or an electrolytic stripping solution containing the plating solution as a component, the plating will not occur. When moving between the tank and the contact/jig stripping tank, the amount of plating liquid carried out can be extremely reduced. That is, in the conventional racking method, the processing liquid adheres to both the object to be plated and the rack and moves.
Therefore, a lot of processing liquid is pumped out and brought in between adjacent processing tanks, which is uneconomical, deteriorates the quality of the plating, and lengthens the processing time. In contrast, in the illustrated plating apparatus, only the cathode contact is moved from one plating tank to the next, and the conveying means and jig are circulated only within the plating tank. Therefore, the amount of Metsuki liquid taken out and brought in is extremely small. In addition, if the stripping solution in the contact stripping tank is a plating solution or an electrolytic stripping solution containing plating solution as a component, even if the plating solution is brought in by the cathode contact, the plating solution will not be removed. There is no deterioration because the and electrolytic stripper are of the same quality. Therefore, there is no need to wash the cathode contact with water after electrolytic stripping, which is economical, improves the quality of plating, and shortens processing time.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main parts of the plating device, and FIG. 2 is a partial perspective view showing the positional relationship between the shielding plate, the anode opening, and the anode. , Fig. 3 is a cross-sectional view of Fig. 1, Fig. 4 is a schematic plan view showing the positional relationship with the shielding plate when the object to be plated is moving, and Fig. 5 is a diagram for the anode when the object to be plated is temporarily stopped. FIG. 3 is a schematic plan view showing the positional relationship with the opening. Drawing code, 1... object to be plated, 2... plating tank, 4... conveying means, 5... holding jig, 6... conveying part, 7... cathode contact, 8... conveying path, 9...
Opening, 10...shielding plate, 11... anode.

Claims (1)

[Claims] 1. In the plating tank 2, an endless conveying means 4 that can move horizontally inside is provided, and on the outer periphery of the conveying means 4,
A holding jig 5 capable of holding the object 1 to be plated in a horizontally long vertical shape is provided continuously, and the cathode contact 7 is endless.
A shielding plate 1 is provided movably within the transport section 6 above the holding jig 5 and has anode openings 9, 9 on both sides of the transport section 6 at regular intervals in the direction of movement.
0 and 10, and parallel anodes 11 and 11 are provided outside the respective anode openings 9 and 9 to both sides of the object to be plated, and the conveying means 4 is connected to the object to be plated so that the central part in the longitudinal direction of the object to be plated is A full-surface plating device characterized in that it is capable of intermittent movement, stopping for a certain period of time when the anode openings 9, 9 of the shielding plates 10, 10 are reached.