JPH0216394B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) This invention relates to a method of electroplating a metal pattern on a plane of an insulating member, a method of electroplating a metal pattern on a plane of an insulating member,
This invention relates to a method and apparatus for electroplating a copper circuit pattern formed by etching.

(Conventional technology) Conventionally, when electroplating industrial products, each product was hung one by one, or all of them were placed in a basket and the basket was hung, and each product was attached to the product through a hanging device from a cathode rod along the outside of the plating solution tank. It allows current to flow through it.

Therefore, in order to plate a metal pattern on only a portion of the plane of the insulating member, it is necessary to use other plating methods instead of electroplating.

(Problem to be Solved by the Invention) For example, during the manufacturing process of printed wiring boards, if the copper foil on the surface is left in the shape of a circuit pattern by etching, then electroplating will be carried out on top of this pattern. It becomes impossible to do so.

At the edge of the circuit pattern formed by etching, the copper foil is exposed. To coat this with a corrosion-resistant metal, solder is applied to the surface of the copper foil in advance, and the temperature is raised after etching so that the solder on the surface flows down to the edges, or directly. There is a method in which the edges are also soldered by bringing them into contact with molten solder.

However, soldering causes pollution problems because it emits fluoride and lead, and countermeasures can be troublesome.
In the case of wiring boards, problems include the extra work of removing solder before gold-plating the circuit terminals, and the extra heating of the board, which tends to cause distortion.

This invention is based on the idea that by making electroplating possible even on localized metal patterns on the plane of an insulating substrate, it not only eliminates the above-mentioned problems, but also expands the applications of electroplating. be.

(Means for Solving the Problems) This invention provides (1) a method of electroplating a metal pattern on a plane of an insulating member, in which only the sliding or rolling power supply surface is exposed, and the other parts are covered with a watertight cathode. and a bare anode are immersed in a plating liquid bath, and the above member is immersed in the plating liquid bath while its metal pattern surface is in relative sliding or rolling contact with the power supply surface. Electroplating method. (2) In a device for electroplating a copper circuit pattern formed by etching on the surface of a printed wiring board, the upper and lower anode plates immersed along the liquid level and bottom of the plating bath are moved horizontally by sliding or rolling. Two cathode plates with only the dynamic power supply surface exposed and the other parts watertightly coated, the power supply surfaces of which are vertically opposed to each other, so that the substrate can pass through the gap with both surfaces in sliding or rolling contact. The pairs of substrates are sequentially arranged horizontally between the upper and lower anode plates, and the substrates are fed one after another from one end of the upper and lower cathode arrays into the gap between the upper and lower power feeding surfaces, and are discharged from the other end of the array. to do,
This is a pattern electroplating device characterized by comprising a vertical feed roller disposed between upper and lower cathode plates.

(Function) In the pattern electroplating method of the present invention, a sliding or rolling power supply surface is provided on the cathode immersed in a plating solution, and the sliding or rolling power supply surface is directly connected to the metal pattern to be plated on the insulating member. in dynamic contact to maintain the potential and current necessary for electroplating. Since plating is performed while moving, uneven plating will not occur even if the cathode is applied to the pattern itself. Then, the patterns sent one after another can be plated in succession.

Since the cathode is covered with a watertight coating with only the power supply surface exposed, even if it is immersed in a plating solution, only the power supply surface is plated, so there is little waste and replacement is easy.

Further, in the pattern electroplating apparatus of the present invention, upper and lower anode plates are immersed along the liquid level and bottom of the plating liquid tank, upper and lower cathode arrays are provided horizontally between them, and the substrate is advanced between the upper and lower power supply surfaces. Since the upper and lower feed rollers are attached, even substrates with circuit patterns on both sides can be sent one after another to the feed rollers and automatically plated evenly on both sides.

(Embodiment) Figures 1 and 2 show a basic embodiment of the present invention.
The insulating member having a metal pattern on a plane is a printed wiring board M in the following embodiments.

In the figure, 1 is the plating liquid tank, 2 is the anode, 3 is the cathode, 4
5 is a feeding roller for feeding the substrate M in the tank, and 6 and 7 are the substrate entrance and exit to the tank 1.

The plating liquid tank 1 is a conventional tank with an inlet 6 and an outlet 7 for inserting the substrate M into the tank walls at both ends.A sponge is placed around the opening edge of both the inlet 6 and the outlet 7 to prevent too much liquid from leaking out. Install and seal. The anode 2 is a normal strip-shaped plate, but the cathode 3 is a copper plate 3a with a copper wire brush 4 attached to the end face to serve as a sliding power supply surface, and the other outer periphery is watertightly covered with resin 3b, as illustrated in FIG. This is what I did.

Although it is convenient to use a commercially available brush 4 as the power supply surface of the cathode 3, it is possible to use the plane of the copper plate as it is as a sliding power supply surface and to have a structure in which it is pressed elastically against the pattern surface. Leave it to the designer's well-known technology, such as using a brush made of titanium, neodymium, etc., or a rolling power supply roller.

Slide the brush 4 directly onto the pattern surface to be plated.
However, as a result of the experiment, I was able to confirm that there was no problem with the quality of the finished matte surface.

FIG. 4 shows an example of the pattern of the printed wiring board M, in which C is a circuit, H is a conductive hole with the back pattern, and T is a terminal portion. It is no wonder that such a dispersed pattern on the surface of an insulating plate has conventionally been considered impossible to electroplat. This invention made it possible for the first time.

The problem with the conventional method is that the gold-plated terminal section mentioned earlier refers to the many T's lined up in Figure 4.
If solder gets on this part, the work to remove it increases.

5 and 6 show enlarged cross-sections of the copper on the surface of the copper-clad substrate material left behind as a pattern circuit C by etching. If the etching resist R is plated before etching, an over ring O that extends beyond the planned width of the pattern circuit C will occur as shown in the figure, and in the subsequent etching, on the contrary,
An undercut U occurs at the edge of the circuit C.
Here, the bare copper is exposed.

According to the invention, when this is coated with a final plating layer 8, a completely corrosion-resistant circuit C is obtained as shown in FIG. Etching resist R also finishing plating layer 8
Also, either Sn-Ni or Sn-Co alloy was used.

An embodiment of the pattern electroplating apparatus of the present invention is shown in FIGS. 7 and 8. Since the plating liquid tank 1 is contained in the outer tank 10, the inlet 6 and outlet 7 of the wiring board M
Even if the plating liquid flows out from the holes in the tank wall through which the drive shafts 5a of the many feed rollers 5 pass, it collects in the outer tank 10. The accumulated liquid is pumped up by a pump 9 and uniformly flows down into the plating liquid tank 1 through a large number of small holes in a distribution pipe 11.

Upper and lower anode plates 2a are arranged horizontally in the plating liquid tank 1, a frame 12 is fixed between them, and all the upper and lower cathodes 3 are attached therein to form a cathode array 13.

Each of the upper and lower cathodes 3 covers the roller 5 to isolate the anode plate 2a and the brush 4 from each other.

A vertical feed roller 5 is disposed between each of the upper and lower cathodes 3, and each drive shaft 5a extends to the outer surface of the side wall of the outer tank 10 and is supported by a bearing. is synchronously driven by.

The wires connecting the upper and lower anode plates 2a and each cathode 3 to the + and - power supplies were ordinary resin-coated wires. Although it was necessary to manually insert the substrate M into the entrance 6, it is easy to automatically feed the substrate M using a conveyor or the like in a production device, and to automatically carry it out when it comes out of the exit.

Although the illustrated embodiments have been described above, it goes without saying that the pattern to be plated is not limited to electric circuits, but can be applied to any metal pattern, and can be varied and applied in a variety of ways depending on the implementation conditions.

(Effects of the Invention) In contrast to the conventional pattern electroplating method of the present invention, in which the anode was immersed in a glazing solution and the cathode was not immersed in the solution, but was connected to the plated item via a hanging tool, etc. ,
Since the cathode itself is immersed in the plating solution, it can be electrically supplied by sliding or rolling even to a small metal pattern on a flat surface of an insulating member. This paved the way for plating hard metals.

Even if the cathode is placed on the pattern to be plated, since it is a sliding or rolling power supply surface, uneven plating will not occur. Furthermore, if the cathode is immersed bare in the plating solution, it will absorb electrolytic metal, but in the present invention, the cathode is coated with watertight coating except for the power supply surface, so there is no risk of this happening.

Furthermore, since the pattern electroplating apparatus of the present invention incorporates the upper and lower cathode arrays and the upper and lower feed rollers, if a board to be printed on both sides is inserted from one end, the circuit patterns plated one after another from the other end. This has a significant productivity improvement effect compared to the conventional substrate feeding method using a hanging tool. Since the anode plates are arranged above and below the upper and lower cathode arrays, the plating quality of the patterns on both sides of the substrate is uniform.

[Brief explanation of drawings]

Figures 1 and 2 are a longitudinal sectional view and a plan view of an embodiment of this invention, Figure 3 is an explanatory diagram of the cathode, Figure 4 is a plane view of an example of a printed wiring board, and Figures 5 and 6 are after etching. An enlarged cross-sectional view of the wiring circuit, a cross-sectional view of the finished plated state, and FIGS. 7 and 8 are a vertical cross-sectional view and a plan view of an embodiment of the device of the present invention. 2, 2a...anode, 3...cathode, 4...sliding power supply surface, 5...feeding roller, 13...cathode arrangement.

Claims (1)

[Claims] 1. In a method of electroplating a metal pattern on a flat surface of an insulating member, only the sliding or rolling power supply surface is exposed, and the other parts are coated with a watertight cathode and a bare anode using a plating solution. Pickled in a tank,
A pattern electroplating method characterized in that the member is immersed in the plating solution bath while the metal pattern surface thereof is brought into relative sliding or rolling contact with the power supply surface. 2. In an apparatus for electroplating copper circuit patterns formed by etching the surface of a printed wiring board, the upper and lower anode plates are immersed along the liquid level and bottom of the plating liquid tank, and the horizontally elongated sliding or rolling power supply surface. A pair of cathode plates with only one part exposed and the other part watertightly coated, the power supply surfaces facing each other vertically, and the substrate passing through the gap by sliding or rolling contact on both surfaces. , sequentially, upper and lower cathode arrays arranged horizontally between the upper and lower anode plates, and the substrates that are successively fed into the gap between the upper and lower power feeding surfaces from one end of the upper and lower cathode arrays, and are discharged from the other end of the array; A pattern electroplating device comprising: a vertical feed roller disposed between upper and lower cathode plates;