JPS589150B2 - Electroless copper plating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electroless copper plating apparatus used for continuous operation of an electroless copper plating solution.

Conventionally, printed wiring boards used copper-clad laminates and removed unnecessary parts by etching to form wiring patterns, but in order to save resources and energy, copper plating was performed only on the necessary patterns on the board. is now required.

Electroless copper plating was developed to meet these demands.

Electroless steel plating is an alkaline copper ion complex solution that uses formalin as a reducing agent to deposit metallic copper on a plating catalyst (such as Pd) or copper surface.

In order to operate electroless copper plating solution stably and continuously,
It is necessary to replenish the components consumed by copper precipitation with a new high-concentration replenisher to keep the composition constant.

1 to 3 show a conventional electroless copper plating apparatus (FIGS. 2 and 3 are enlarged views of section A in FIG. 1).

), In the figure, 1 is a plating tank, 2 is a circulation pump, 3 is a circulation pump, 4 is a filter, 5 is a replenisher addition pump, 6 is a replenisher introduction pipe, 7 is a mixer, 8 is a replenisher tank, and 9 is a replenisher tank. The controller, 10 is a replenisher, and 11 is a stationary interface between the replenisher and the plating solution.

Conventionally, such devices refilled the necessary amount of replenisher intermittently, so during periods when replenisher was not being discharged,
A stationary contact interface 11 between the highly concentrated replenisher and plating solution as shown in FIG. 2 is formed, and a local runaway reaction occurs, and as shown in FIG. Phenomena such as precipitation (12), copper oxide adhesion (13), or formation of copper hydroxide and clogging of the replenisher inlet pipe (14) occurred.

In addition, when such copper oxide and copper hydroxide are brought into a plating bath, they cause a runaway reaction known as copper precipitate. The present invention has been made in view of these points, and is based on A. A accumulating tank B equipped with a circulation pipe that circulates the plating solution as needed. In an electroless copper plating apparatus comprising a replenisher supply device that has a replenisher inlet pipe opened into the plating solution and intermittently supplies replenisher into the plating solution, the replenisher inlet pipe has a plating solution, This system is characterized in that a liquid that does not cause a runaway reaction even when it comes into contact with the replenisher is introduced, and the replenisher remaining in the replenisher introduction pipe is removed.

To remove the replenisher remaining in the replenisher inlet pipe by introducing a liquid that does not cause a runaway reaction when it comes into contact with the plating solution or replenisher, such as water (non-reactive liquid), into the replenisher inlet pipe. (a) The non-reactive liquid is continuously flowed into the replenisher inlet pipe, that is, the replenisher is intermittently added to the non-reactive liquid that is constantly flowing in, and a mixture of the two is added to the plating liquid. so that

(b) After adding the required amount of replenisher, flow non-reactive liquid into the replenisher inlet pipe until the next replenisher is added.

In other words, after adding the required amount of replenisher and until the next addition, a solution that does not cause a runaway reaction with the replenisher and plating solution is constantly flowed into the replenisher flow path, and the interaction between the replenisher and plating solution is maintained. Avoid static contact interface formation.

(c) After adding the required amount of replenisher, a sufficient amount of non-reactive liquid to replace the replenisher remaining in the replenisher inlet pipe is introduced into the replenisher inlet pipe.

That is, after adding the required amount of replenisher, the replenisher remaining in the replenisher flow path is replaced with a solution that does not cause a runaway reaction with the replenisher and the plating solution.

This can be done by the following methods.

FIG. 4 is a system diagram showing the piping of the replenisher supply device when removing the replenisher remaining in the replenisher introduction pipe by method (a), where 2 is a circulation pipe and 5 is a replenisher addition pump. , 6 is a replenisher inlet pipe, 8 is a replenisher tank, 9 is a controller, 15 is a water tank 16 is an addition pump, which is always switched on.

FIG. 5 is a system diagram showing the piping of the replenisher supply device in the case of methods (B) and (C), where 17 is an addition pump;
In the case of b), it is set so that it turns off and on when the replenisher addition pump 5 is on and off, respectively, and (
In case c), the replenisher pump 5 is set to be turned on for a certain period of time after being turned off.

In the above explanation, the replenisher inlet pipe opened into the plating solution in the circulation pipe, that is, the replenisher was added into the circulation pipe, but the replenisher inlet pipe The present invention can also be used when the replenisher is inserted directly into the plating solution in the plating tank and the replenisher is directly added to the plating tank.

EXAMPLE An electroless copper plating solution was continuously operated for 24 hours using the replenisher supply device shown in FIG.

The flow rate in the pipe is 100/min, and the maximum amount of replenishment liquid is 200ml.
/min total plating solution volume is 700l, plating solution composition is pH 12.0, CuSO4・5H2O 10g/lED
TA30g/l, NaCN30mg/l, GAFAC・
RE-610 (trade name, surfactant manufactured by Toho Chemical Industry Co., Ltd.) 0.25 ml/l, HCHO 6 ml/l, temperature 7
It is 2℃.

After the operation was completed, the end of the replenisher inlet pipe was examined and found that copper hydroxide, copper hydroxide,
No adhesion of copper oxide or precipitation of copper was observed at all, and no copper splatter occurred in the entire plating solution.

In the conventional replenisher addition method, copper hydroxide or copper oxide adheres to the tip of the replenisher inlet tube, or copper precipitates, resulting in clogging of the replenisher outlet or copper hydroxide. There were problems such as fine particles of copper oxide floating in the liquid and becoming the core of a runaway reaction, reducing the stability of the liquid.

However, according to the device of the present invention as explained above, there is no stationary interface between the replenisher and plating solution, and there is no local runaway reaction at the tip of the replenisher introducing tube.
This area was no longer clogged and the stability of the liquid was improved.

[Brief explanation of drawings]

Figures 1 to 3 are cross-sectional views of conventional electroless copper plating equipment.
FIGS. 4 and 5 are system diagrams of the replenisher supply system piping used in the electroless copper plating apparatus of the present invention. Explanation of symbols, 1... Plating tank, 2... Circulation pipe,
3... Circulation pump, 4... Filter, 5... Replenisher addition pump, 6... Replenisher introduction pipe, 7... Mixer, 8... Replenisher tank, ... Controller, 1
0... Replenisher, 11... Replenisher liquid static interface, 12... Precipitated copper, 13... Adhered copper oxide, 14
...Clogged copper hydroxide, 15.. Water tank, 16. Addition pump, 17.. Addition pump.

Claims (1)

[Claims] 1 A. A accumulating tank B equipped with a circulation pipe that circulates the plating solution as needed. In an electroless copper plating apparatus comprising a replenisher supply device that has a replenisher inlet pipe opened into the plating solution and intermittently supplies replenisher into the plating solution, the replenisher inlet pipe has a plating solution, An electroless copper plating apparatus characterized in that a liquid that does not cause a runaway reaction even when it comes into contact with the replenisher is introduced to remove the replenisher remaining in the replenisher introduction pipe.