JPS589148B2 - Electroless plating device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electroless plating apparatus.

Conventionally, printed wiring boards use copper-clad laminates and remove unnecessary parts to form wiring patterns, but in order to save resources and energy, copper is plated only on the necessary patterns on the board. is now required.

Electroless copper plating solution was developed to meet these demands.

The electroless copper plating solution is an alkaline copper ion complex solution, which serves as an HCH brazing agent to deposit metallic copper on a plating catalyst (such as PD) or on a copper surface.

Electroless copper plating solution is a relatively unstable solution, so in order to obtain deposited copper with stable performance, it is necessary to control elements such as composition, temperature, and specific gravity. The removed components must be replenished with a new high-concentration replenisher.

FIGS. 1 and 2 show an example of a conventional replenisher adding device.

FIG. 2 is an enlarged sectional view of section A in FIG. 1.

In the figure, 1 is a plating tank, 2 is a pipe, 3 is a circulation pump, and 4
5 is a filter, 5 is a replenisher addition pump, 6 is a replenisher introducing pipe, 7 is a replenisher tank, 8 is a plating solution, and 9 is a replenisher.

In such a device, even if the flow rate in the circulation pipe is increased, it is difficult for the added replenisher to diffuse and mix in a direction perpendicular to the flow.

Therefore, a point where the concentration is abnormally high occurs in the plating solution, and a runaway reaction (runaway reaction) occurs in which metallic copper is formed not only on the object to be plated but also in the solution.
(copper free).

In particular, when only copper ions are used as a replenisher, complexation is slow and copper hydroxide and copper oxide are formed, which tends to cause copper staleness.

In this way, in the conventional device, as shown in Figure 2, the flow inside the tube is substantially laminar flow or plug flow, so the streamlines are parallel to the flow, and the replenisher flowing out from the center of the tube flows through a narrow introduction. The slight turbulence created by the tubes causes only vertical mixing.

The present invention has been made in view of these points, and is an electroless plating device that connects a plating bath, a replenisher adding device, a circulation pump, and a filter with a pipe and circulates the plating solution. It is characterized by the provision of a turbulent flow former.

That is, in the plating apparatus of the present invention, a turbulence former fixed in the tube is installed to speed up the mixing and diffusion of the introduced high-concentration replenisher into the plating solution.

Example 1 Turbulence former shown in Fig. 3 (a is a front view, b is a side view)
10 was inserted into the flange connection part of a PVC pipe having an inner diameter of 5 cm as shown in FIG. 4, and the replenisher was introduced from just before the turbulence former.

The flow rate in the pipe is 100 l/min, and the maximum amount of replenisher added is 20 l/min.
0ml/min, replenisher addition amount up to 200ml/min
n. The total plating solution volume is 700 liters.

Using this equipment, PH120, CuSO4・5H2O1
0g/l, EDTA30g/l, NaCN30mg/l
, GAFAC-RE610 (surfactant, trade name manufactured by Toho Chemical Co., Ltd.) 0.25ml/l, HCHO 6ml/l
When the electroless copper plating solution was operated at 72°C, no copper flaking occurred and the performance of the deposited copper foil was sufficient.

Example 2 Turbulence former shown in Fig. 5 (a is a front view, b is a side view)
Immediately after that, a replenisher was introduced using No. 11.

The plating solution was operated under the same conditions as in Example 1, but there was no copper loss and sufficient amount of copper was deposited.

In the conventional replenisher introduction method, mixing and diffusion of the replenisher was poor, and a runaway reaction (copper removal) of the plating solution was likely to occur.

Therefore, the runaway reaction of the plating solution could be suppressed by providing a turbulence former between immediately before and after the replenisher introduction point to promote mixing and diffusion of the replenisher.

In addition to the turbulent flow generator shown in the drawings, it is also possible to use a turbulent flow generator such as a board with a width half the diameter of the pipe, a slit, or a drainboard shape.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a conventional electroless plating apparatus, FIG. 2 is an enlarged sectional view of section A in FIG. FIG. 4 is a cross-sectional view of the turbulence shaper attachment point, and FIG. 5 is another turbulence shaper, with a being a front view and b being a side view. Explanation of symbols 1... plating tank, 2... pipe, 3...
・Circulation pump, 4... Filter, 5... Replenisher addition pump, 6... Replenisher introduction pipe, 7... Replenisher tank, 8... Plating solution, 9... Replenisher, 10... Turbulence former, 11... Turbulence former.

Claims (1)

[Claims] 1. In an electroless plating device in which a plating tank, a replenisher adding device, a circulation pump, and a filter are connected by a pipe and a plating solution is circulated, a turbulence former is provided inside the pipe. Electroless plating equipment featuring: 2. The electroless plating apparatus according to claim 1, characterized in that a turbulence former is provided inside the pipe immediately after the location where the replenisher is added into the pipe from the replenisher adding device. 3. The electroless plating apparatus according to claim 1, characterized in that a turbulence former is provided inside the pipe immediately before the location where the replenisher is added into the pipe by the replenisher adding device.