JPH0354140Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is used in the etching process of electric circuit boards such as printed wiring boards, in which copper dissolved in the etching solution is converted into copper sulfate crystals by cooling crystallization. The present invention relates to an etching solution transfer and circulation device for reusing the etching solution after recovery.

[Conventional technology]

When manufacturing electrical circuit boards such as printed wiring boards, an etching solution containing hydrogen peroxide or sulfuric acid as a main component is used to remove a specific amount of copper or copper alloy, and the temperature of the solution is maintained at at least 30°C. An etching process is performed. Since copper dissolves and accumulates in this etching solution during use, the surplus is recovered without decomposing the residual hydrogen peroxide, and then this solution is reused as an etching solution. Ta.

To recover the copper in the etching solution without decomposing the residual hydrogen peroxide, the etching solution should be
It is preferable to recover copper sulfate crystals by a cooling crystallization method in which the solution is cooled to 20°C or lower.In order to make it easier to reuse the subsequent solution as an etching solution with a low copper concentration, for example, As shown in the above publication, an apparatus was used in which an etching bath and a copper sulfate recovery apparatus were connected through a circulation path to transfer and circulate the etching solution.

[Problem that the invention attempts to solve]

However, when the etching solution from which copper has been recovered in the copper sulfate recovery equipment is returned to the etching tank for use, or due to a drop in outside temperature such as in winter, crystals may form in the solution in the return route, causing the route to become clogged. However, it sometimes became impossible to forcibly transfer the liquid using the pump.

The present invention is an etching solution that prevents the formation of crystals during the return of the etching solution from which excess copper is collected and is returned to the etching tank, and allows for smooth forced transfer of the solution using a pump without clogging the return path. The object is to provide a transfer circulation device.

``Means for Solving the Problems'' The present invention consists of an etching bath and a copper sulfate recovery device for reusing the etching solution after recovering the copper dissolved in the etching solution as copper sulfate crystals by a cooling crystallization method. an intermediate tank installed near the copper sulfate recovery device in the return path from the copper sulfate recovery device to the etching tank in the circulation path and equipped with heating means and stirring means; This is an etching liquid transfer/circulation device characterized in that a heating means is attached to a return path from the intermediate tank to the etching tank.

[Effect]

In the present invention, the excess copper is recovered in the copper sulfate recovery device, and the etching solution sent back to the etching tank flows out of the copper sulfate recovery device and immediately flows into the intermediate tank where it is uniformly heated. The liquid temperature is maintained in the return route from the etching tank to the etching tank, regardless of the drop in outside temperature, and the solution can be returned to the etching tank without crystals forming in the solution, without clogging the return route. The forced transfer by a pump is also carried out smoothly, and furthermore, depending on the degree of heating, the material can be reused in the etching tank without being reheated.

〔Example〕

One embodiment of the present invention will be described with reference to the drawings. 1 is a tank of a copper sulfate recovery device;
A stirring impeller 4 rotated by a motor 3 is provided in an inner cylinder 2 provided concentrically inside the
A cooling jacket 6 is provided around the outer periphery of the tank 1 into which a cooling medium such as cooling water supplied from the cooler 5 is introduced.
is provided. A copper sulfate outlet 7 is opened at the bottom of the tank 1. A screw conveyor 9 driven by a drive device 8 is provided at the copper sulfate outlet 7, and a discharge port 10 is provided near the end of the screw conveyor 9.

11 is an etching tank;
and tank 1, from etching tank 11 to pump 1.
A circulation path is formed by a transfer pipe 13 through which the etching liquid flows to the inner cylinder 2 of the tank 1 via the etching tank 2, and a return path from the tank 1 to the etching tank 11. an overflow pipe 16 that connects the liquid overflow port 14 and an intermediate tank 15 installed near the tank 1, and an intermediate tank 15;
It is comprised of a return pipe 18 having a pump 17 that connects the intermediate tank 15 and the etching tank 11.

The intermediate tank 15 is equipped with a heater such as an electric heater 19, a temperature sensor 20, an agitator 21, a liquid level gauge 22 for controlling the liquid level, and a circulation pipe 24 with a pump 23 and a return pipe 18. It is connected to the circulation pipe 25 that was used.

Note that the circulation pipe 24 is connected to the tank 1 from the middle.
It is preferable to branch the branch pipe 26 connected to the overflow pipe 16 near the connection with the overflow port 14 of the pipe.

Further, the return piping 18 between the intermediate tank 15 and the etching tank 11 is kept warm so as not to be affected by the outside temperature by using a heat insulating jacket, and a heating medium is introduced into this heat insulating jacket so that the return pipe 1
It is also preferable to be able to raise the temperature of the liquid in 8.

Therefore, the used etching solution used in the etching tank 11 and in which the excess copper has dissolved is
When the liquid is transferred to the tank 1 via the transfer pipe 13 by the pump 12 and cooled by the cooling medium fed from the cooler 5 to the cooling jacket 6, the copper dissolved in the liquid is converted into copper sulfate crystals. It crystallizes and settles to the bottom of tank 1. The precipitated copper sulfate crystals are
The copper sulfate is transported from the copper sulfate outlet 7 by the screw conveyor 9 and discharged from the discharge port 10 to the outside of the system.

On the other hand, the liquid after excess copper has been recovered as copper sulfate is replenished with hydrogen peroxide, sulfuric acid, etc., overflows from the overflow port 14, and is immediately led to the intermediate tank 15 via the overflow pipe 16.

The liquid led from the tank 1 to the intermediate tank 15 is stirred by an agitator 21 here, and is also passed through circulation pipes 24, 2.
Electric heater 1 is heated while the liquid in the tank is circulated by
9. After being uniformly heated to a predetermined temperature by the temperature sensor 20, etc., the etching liquid is returned as an etching liquid to the etching tank 11 via the return piping 18 by the pump 17, and is reused. When returning the etching solution, since the return pipe 18 is kept warm, the temperature of the solution heated in the intermediate tank 15 is maintained at almost the same temperature regardless of the drop in the outside temperature, and no crystal formation is observed in the solution. It can be smoothly returned to the etching tank 11. In some cases, it may be convenient to reheat the return pipe to a temperature suitable for etching.

In addition, a branch pipe 26 is connected to the circulation pipe 24 of the intermediate tank 15.
If the liquid heated in the intermediate tank 15 is circulated near the connection part of the overflow pipe 16 with the tank 1, it is possible to prevent crystals from adhering to the vicinity of the overflow port 14 of the tank 1. be able to.

[Effect of idea]

As described above, according to the present invention, when the surplus dissolved copper is recovered as copper sulfate crystals and recycled for reuse, the formation of crystals due to the drop in liquid temperature caused by the outside temperature, which is likely to occur during the return route, is prevented. However, the forced transfer of liquid by the pump can be made smooth, the etching process can be made efficient and economical, and productivity can be improved.

[Brief explanation of the drawing]

FIG. 1 is a system explanatory diagram showing an embodiment of the present invention. 1...tank, 2...inner cylinder, 3...motor, 4
... Stirring impeller, 5 ... Cooler, 6 ... Cooling jacket, 7 ... Copper sulfate outlet, 8 ... Drive device,
9...screw conveyor, 10...discharge port, 1
1... Etching tank, 12, 17, 23... Pump, 13... Transfer piping, 14... Overflow port, 15...
...Intermediate tank, 16...Overflow pipe, 18...Return pipe,
19...Electric heater, 20...Temperature sensor, 21
... Stirrer, 22 ... Liquid level gauge, 24, 25 ... Circulation piping, 26 ... Branch pipe.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. After recovering copper dissolved in an etching solution as copper sulfate crystals by a cooling crystallization method, an etching tank and a copper sulfate recovery device are connected in a circulation path in order to reuse this etching solution. In the connected devices, an intermediate tank installed near the copper sulfate recovery device and equipped with heating means and stirring means is interposed in the return path from the copper sulfate recovery device to the etching tank in the circulation path, and this An etching liquid transfer and circulation device characterized in that a heat retaining means is attached to a return path from an intermediate tank to the etching tank. 2. The etching liquid transfer and circulation device according to claim 1, wherein the heat retaining means includes a heating means. 3. The etching liquid transfer and circulation apparatus according to claim 1 or 2, wherein the stirring means provided in the intermediate tank includes means for circulating the liquid in the tank. 4. The etching solution transfer and circulation device according to claim 3, wherein the circulation means includes a path connecting the intermediate tank and the vicinity of the connecting portion of the return path with the copper sulfate recovery device.