JPS6241317B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in electroless composite nickel plating equipment.

There is an electroless composite nickel plating method, which uses non-conductive powder such as carbon random (SiC) or diamond as a composite material and performs plating while dispersing them so that the composite material is included in the plating layer. . In the electroless nickel plating method, impurities such as iron mixed into the plating solution for some reason or composite materials such as the above-mentioned SiC serve as nuclei and grow grains, forming so-called spherical nickel precipitates, and sometimes these occur in large quantities. They may aggregate into plate-like nickel precipitates.

In the electroless nickel plating method using composite materials such as SiC, the generation of the above-mentioned spherical nickel precipitates is unavoidable, but in view of the management of the plating solution, that is, workability and efficiency, the generation of spherical nickel precipitates should be avoided. There is a strong demand in the process to reduce or separate the composite material and the spherical nickel precipitates. In addition, when discarding plating solution that has become unusable due to the formation of spherical nickel precipitates, all of the used solution must be extracted and replaced. For this reason, all plating solution is treated with a nitric acid solution and the plating solution containing Nickel ions had to be discarded as nitrates. Such a situation is not desirable from the viewpoint of resource saving, and also poses a heavy burden on the process.

The present invention has been made to eliminate the drawbacks of the conventional electroless nickel plating method described above, and includes a means for attenuating the air stirring force to retain spherical nickel deposits that have grown to a predetermined diameter or more at the bottom of the plating tank. The present invention also provides an electroless composite nickel plating device which is capable of selectively removing spherical nickel precipitates having a diameter larger than the predetermined diameter.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a side view illustrating an electroless composite nickel apparatus according to the present invention, in which 1 is an object to be plated, 2 is a plating tank, 3 is an air stirring device, 4 and 6 are discharge ports, and 5 is the above-mentioned predetermined This is a damping plate for separating spherical nickel precipitates larger than the diameter.

In the above apparatus, when spherical nickel precipitates grow using composite materials such as SiC or iron mixed in the plating solution as nuclei, the larger the diameter, the stronger the tendency for them to stagnate in the lower layer of the plating tank 2. The distribution map in Figure 2 shows this situation. As shown in the figure, the larger the particle size of the spherical nickel precipitates, the more they stay in the lower layer. In addition, the 4μ particles are SiC
Composite materials such as

In the plating liquid, the force acting on the composite material such as SiC or the spherical nickel precipitate is composed of three factors: A, the weight of the particles, B the buoyancy in the plating liquid, and the buoyancy due to air agitation, with the buoyancy due to air agitation being particularly large.

The air agitation force in this example was sufficient to uniformly disperse composite particles of 4 μ in size in the plating solution, and spherical nickel precipitates of about 20 μ in size were found near the middle layer, especially those that had grown to 500 μ in size or more were buoyant. As a result, the amount of water decreases significantly and becomes stagnant in the lower part of the plating tank 2.

In this embodiment, the damping plate 5 almost completely prevents the spherical nickel precipitates that have grown to a predetermined diameter from moving back to the upper layer, making it possible to separate such particles. This effect can be obtained because the presence of the damping plate 5 causes a change in the air agitation force between the lower layer and the upper layer, and the lower layer of the damping plate 5 becomes the same as without the damping plate 5. Board 5
This is because the air stirring force in the upper layer is attenuated by the presence of the attenuation plate 5. This makes it possible to confine spherical nickel precipitates that have grown to a predetermined diameter or more in the lower layer of the damping plate 5.

In this way, the plating liquid discharged from the discharge port 6 becomes a plating liquid in which only the composite material is dispersed, with almost no spherical nickel precipitates, and can be used continuously. Furthermore, the plating liquid discharged from the discharge port 5 contains spherical nickel precipitates, has a high content concentration, and has a small amount of liquid, making it extremely easy to remove the spherical nickel precipitates. Therefore, compared to the conventional technique, which required the entire amount of plating solution to be scorched and discarded, the number of steps is significantly reduced.

FIGS. 3a and 3b are plan views of embodiments of the damping plate 5, showing a wire mesh type and a lattice type, respectively. Note that the mesh should preferably be 5 to 20 mm so as not to interfere with air agitation. Note that the shapes of the embodiments are merely examples, and the shape is not limited thereto.

FIG. 4 is a side view illustrating another embodiment of the present invention, in which the same parts as in FIG. 1 are designated by the same reference numerals. In this embodiment, a second air agitation device 7 is provided above the damping plate 5. By controlling the first air stirring device 3 and the second air stirring device 7, the spherical nickel precipitates can be better contained in the lower layer of the damping plate 5.

FIG. 5 is a side view illustrating still another embodiment of the present invention, in which the same parts as in FIG. 1 are designated by the same reference numerals, and 8 is a magnet. In this embodiment, the presence of the magnet 8 prevents the spherical nickel precipitates that have once entered the lower layer of the damping plate 5 from entering the upper part of the damping plate 5 again.

Note that a synergistic effect can be expected by providing the second air stirring device 7 in the embodiment shown in FIG. 4 and the magnet 8 in the embodiment shown in FIG. 5 together and using them in combination.

The electroless composite nickel plating apparatus according to the present invention has the above-described configuration, thereby preventing the spherical nickel precipitates from dispersing to the upper part of the plating tank in the plating solution, and preventing the spherical nickel precipitates from dispersing onto the object to be plated. It reduces adhesion, is favorable for managing the attenuated plating solution, and improves the finished state of the object to be plated. Furthermore, by separating and recovering the plating liquid on the upper and lower parts of the attenuation plate, only the lower plating liquid with a high concentration of spherical nickel precipitates needs to be discarded, resulting in process and resource savings, as well as pollution prevention. It is very suitable from the viewpoint of , and its effects are great.

[Brief explanation of the drawing]

Figures 1, 4, and 5 are side views of an embodiment of the electroless composite nickel plating device according to the present invention, Figure 2 is a distribution diagram of spherical nickel precipitates in the plating tank, and Figures 3a and b FIG. 2 is a plan view of an embodiment of a damping plate used in the present invention. 1...Object to be plated, 2...Plating tank, 3, 7...
...Air stirring device, 4, 6...Discharge port, 5...Dampening plate, 8...Magnet.

Claims (1)

[Scope of Claims] 1. In an electroless composite nickel plating device in which an air stirring device is provided at the bottom of the plating tank, air stirring is used to separate spherical nickel precipitates that have grown to a predetermined diameter or more into the lower layer of the plating tank. An electroless composite nickel plating device characterized in that a force damping means is provided at a position spaced apart from the bottom of the plating tank. 2. The electroless composite nickel plating apparatus according to claim 1, wherein the air stirring force damping means comprises a damping plate having a mesh of 5 to 20 mm. 3. The damping means for the air stirring force comprises the damping plate set forth in claim 2 and a second air stirring device provided above the damping plate, as set forth in claim 1. electroless composite nickel plating device. 4. The electroless composite nickel plating device according to claim 1, wherein the air stirring force damping means comprises a damping plate having a mesh of 5 to 20 mm and equipped with a magnet.