JP2007146213A - Plating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppressing components in a plating liquid from being vaporized caused by the introduction of a gas into the plating liquid. <P>SOLUTION: A plating tank is made possible to be blocked from the outside air, and the gas passing through the plating liquid is collected and introduced again into the plating tank together with a fresh gas, thereby suppressing the components from being vapourized while keeping the total flow rate of the gas and also reducing the use consumption of the gas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plating apparatus, and more particularly to an electroless copper plating apparatus, an electrolytic gold plating apparatus, and an electroless gold plating apparatus.

  In the electronic industry, the surface of an insulating material is widely coated with electroless plating. For example, in the production of a printed circuit board, electroless copper plating is performed on a through hole to make it conductive. In addition, it is increasingly used for wiring formation on a ceramic substrate or the like.

  For electroless copper plating, a plating solution containing copper, alkali, and formaldehyde is most often used. Formaldehyde is a harmful substance to the human body, and it is desired to reduce the amount used and discharged with the recent increase in environmental awareness. Glyoxylic acid has been studied as an alternative substance, but has not yet been widely used.

  In general plating, stirring is widely performed by bubbling gas in a plating solution. Agitation by gas is effective for both electroplating and electroless plating because a random agitation effect can be obtained, and the agitation effect can be large due to the high rate of bubbles rising.

  Further, it is known that it is important to keep the dissolved oxygen concentration appropriate in the electroless copper plating solution. This is because the rate of the plating reaction can be influenced by the dissolved oxygen concentration, which can cause variation, and if the dissolved oxygen concentration is too low, cuprous oxide can be generated by reducing the copper ions to promote the decomposition of the bath. It depends on something. Therefore, it is common practice to constantly bubble air through the electroless copper plating solution to maintain the dissolved oxygen concentration.

  FIG. 4 is a view showing a conventional plating apparatus. The plating tank 101 is filled with a plating solution, and foreign matter is removed by a circulation, a filtration mechanism and a temperature adjustment mechanism (not shown), and the temperature is maintained at a temperature suitable for plating. An air diffuser 103 is disposed inside the plating tank 101, and air sent from the compressor 104 is introduced into the plating solution. The flow rate of air is controlled by the regulator 112, and the dissolved oxygen concentration is monitored by the dissolved oxygen meter 113.

In addition to such a structure, the following document describes air temperature adjustment and the like.

On the other hand, gold plating is also used in various situations because of the stability of the connection of the plated wiring to the solder and the weather resistance of the surface. As the gold plating solution, electrolytic plating and electroless plating have conventionally been used with a plating solution using a cyanide compound. However, in recent years, sulfite is mainly used as a plating solution that does not contain a cyanide compound from the environmental and safety aspects. Gold plating solutions have been used. However, sulfite ions are easily combined with oxygen to become sulfate ions, and the complexing action on gold ions is lost. For this reason, nitrogen gas is bubbled to remove dissolved oxygen so that sulfite ions do not react with dissolved oxygen.

FIG. 5 is a view showing a conventional gold plating apparatus. The plating tank 101 is filled with a plating solution, and foreign matter is removed by a circulation, a filtration mechanism and a temperature adjustment mechanism (not shown), and the temperature is maintained at a temperature suitable for plating. The plating tank 101 is provided with a lid 102, and an aeration tube 103 is arranged inside the plating tank 101, and the nitrogen gas sent from the nitrogen cylinder 115 is introduced into the plating solution after the flow rate is adjusted by the regulator 112. ing.
JP-A-6-280034

  In the conventional electroless plating tank, the bubbled gas is released as it is to the atmosphere as shown in FIG. 5, or is processed as exhaust of the entire apparatus. In addition to the original gas, this gas includes hydrogen gas generated during plating and components volatilized from the plating solution.

  In electroless copper plating, a particular problem is volatilization of formaldehyde. Formaldehyde is a gas at room temperature and volatilizes easily by bubbling.

  Although the volatilization amount varies depending on the conditions, the rate of decrease of the formaldehyde concentration may reach about 0.1 to 0.2 g / L / hour. In order to prevent the characteristics of the plating solution from changing due to the decrease due to the volatilization, it was necessary to replenish periodically. In addition, since it is not appropriate to release the volatilized component as exhaust as it is to the environment, it is necessary to install equipment with sufficient processing capacity for the treatment.

  Furthermore, since the plating solution is alkaline, there is a problem that the pH is reduced by taking in carbon dioxide in the air. In order to compensate for this pH decrease, an alkali such as sodium hydroxide had to be added.

  In gold plating, handling of nitrogen to be bubbled has been a problem. In order to obtain the effect of liquid stirring by bubbling, a considerable flow rate was required, and consumption of nitrogen was intense.

This invention is made | formed in view of this point, and it aims at suppressing the increase in the chemical usage-amount by bubbling to an electroless-plating liquid, and the increase in the usage-amount of gas.

  The method for producing a plated product according to the present invention is characterized in that the gas discharged from the plating solution surface in the plating tank is collected, and the gas is supplied as a stirring gas for the plating solution in the plating tank.

  By bubbling the gas that has once passed through the plating solution with this configuration, volatilization of the components in the plating solution can be suppressed. This is because the volatilization rate from the liquid to the gas decreases when the concentration of the volatile component in the gas increases, and it becomes difficult for the gas that has already passed through the plating solution and already contains the volatile component to volatilize again. Because. In addition, components that are desired to be supplied to the plating solution by bubbling are hardly dissolved in the plating solution by one bubbling, and can be circulated for use.

  Moreover, the plating apparatus of the present invention includes a gas flow path that allows the gas discharged from the plating solution surface portion in the plating tank to pass therethrough, and a gas recovery means that is connected to the gas flow path and collects the gas in the gas flow path. And a ventilation means for supplying the gas recovered by the gas recovery means into the plating solution.

  With this configuration, the gas once passed through the plating solution can be collected and bubbled, and the volatilization of components in the plating solution can be suppressed.

  Moreover, the plating apparatus of the present invention is characterized by having an outside air blocking means that is provided above the plating solution surface portion and suppresses the outside air from being mixed into the gas flow path.

  With this configuration, it is possible to collect the gas discharged from the plating solution surface without entraining the outside air, and it is possible to suppress volatilization of active components that are not desired to be volatilized, such as formaldehyde, in copper plating, and the outside air in gold plating. It is possible to prevent components such as oxygen in the plating bath from becoming unstable.

  Moreover, the plating apparatus of the present invention is provided with a gas blocking means that is provided above the plating solution surface portion and suppresses the gas discharged from the portion directly above the object to be plated from being mixed into the gas flow path. To do.

  Since hydrogen generated during plating has a reducing power, if introduced into the plating solution, the balance of the bath may be lost, and the plating rate may vary or the plating solution may become unstable. Hydrogen is generated only from the object to be plated and is discharged upward as bubbles. For this reason, it can suppress that the gas containing much hydrogen discharged | emitted from the to-be-plated object part mixes in a gas flow path by providing a gas shielding means. Therefore, the hydrogen concentration of the gas recovered by the recovery means is reduced, and it is difficult for the situation where the balance of the plating bath is lost due to bubbling.

  Further, the plating apparatus of the present invention is provided with an exhaust port for discharging a part of the gas in the gas flow path, and this exhaust port is abolished above the gas intake port of the gas recovery means. .

  Since hydrogen is a gas with a low density, it has a property of moving upward, while formaldehyde that is desired to suppress volatilization from the plating solution has almost the same density as air and does not move upward. For this reason, hydrogen is preferentially discharged in the gas flow path by providing the exhaust port above the intake port. Therefore, the hydrogen concentration of the gas recovered by the recovery means is reduced, and it is difficult for the situation where the balance of the plating bath is lost due to bubbling.

  Further, the plating apparatus of the present invention is characterized by having a gas supply means for supplying a gas other than the gas recovered by the gas recovery means into the plating solution.

  With this configuration, it is possible to supply the plating solution by bubbling with a gas that sufficiently contains the component to be supplied to the plating solution and a gas that can be prevented from volatilizing the component once it has passed through the plating solution. It is possible to maintain the concentration of the components necessary for bubbling while suppressing the above. Moreover, it becomes possible to supply the gas which changed the density | concentration of the component to supply to a plating solution as needed of each part, such as a part which becomes high temperature, and a part with a to-be-plated object.

  Also, with this configuration, the plating solution contains a gas that does not contain any component that is desired to be removed from the plating solution by bubbling, and a gas that contains a component that is desired to be removed once through the plating solution but has a sufficiently low concentration compared to the outside air. Thus, it is possible to ensure a bubbling flow rate while suppressing the amount of gas used.

  Further, the plating apparatus of the present invention is characterized in that a gas mixing means for mixing the gas supplied from the gas recovery means and a gas other than the gas recovered by the gas recovery means and leading to the ventilation means is provided. To do.

  With this configuration, it is possible to bubble the recovered gas and a gas other than the recovered gas into the plating solution without providing a plurality of ventilation means in the plating solution.

  Moreover, the plating apparatus of the present invention is characterized in that a flow rate adjusting means capable of independently controlling the flow rate of the gas from the gas supply means and the gas recovery means is provided.

  With this configuration, it is possible to control the concentration of the component in the gas to be supplied to the plating solution.

  Moreover, the plating apparatus of the present invention provides at least one of the concentration of the gas component in the gas flow path and the concentration of the gas component dissolved in the plating solution with respect to one or more gas components contained in the gas. A gas concentration measuring means for measuring one is provided.

  With this configuration, it is possible to perform feedback control while actually measuring the concentration of the gas component, and to control the concentration of the gas component more precisely.

As described above, according to the plating apparatus of the present invention, it is possible to sufficiently suppress the volatilization of components from the plating solution while sufficiently supplying the components in the gas to be supplied to the plating solution by bubbling. It becomes possible to suppress the replenishment amount.
Moreover, according to the plating apparatus of this invention, it becomes possible to suppress the usage-amount of fresh gas, suppressing the density | concentration of the component to remove from a plating solution by bubbling low.

  Hereinafter, the present invention will be described in more detail.

  FIG. 1 is a diagram showing an example of a plating apparatus according to the present invention. The plating tank 1 is filled with an electroless copper plating solution mainly composed of copper sulfate, formaldehyde, sodium hydroxide, and a complexing agent, and foreign matter is removed by a circulation, a filtration mechanism and a temperature control mechanism (not shown). It is kept at a suitable temperature.

  The plating tank 1 can be blocked from the outside air, and the object 7 can be taken in and out from the lid 2. Inside the plating tank 1, an air diffuser 3 is disposed as a ventilation means. The ventilation means may be simply a shape in which a hole is formed in the tube or a means capable of generating fine bubbles using a porous body.

  The air sent from the supply compressor 4 as the gas supply means and the gas sent from the recovery compressor 5 as the gas recovery means are supplied to the air diffusion pipe 3 by the pipe joint 6 as the gas mixing means. It has been mixed and introduced. As the gas supply means, not only a compressor for compressing air but also an air pump, a compressed air line installed in a factory, an air cylinder, a mixed gas from a nitrogen cylinder and an oxygen cylinder, or the like can be used. As the gas recovery means, not only a compressor but also an air pump or the like can be used.

  The gas bubbled into the plating solution from the air diffuser 3 reaches the gas flow path 8 and is supplied again to the plating solution from the recovery compressor through the air intake port 9 to the gas recovery means. Moreover, the exhaust port 10 is installed above the intake port 9, and gas with low density is discharged preferentially. Further, a partition 18 as a gas blocking means is provided immediately above the object 7 to be plated, and the flow path 8 is partitioned to form a second gas flow path 8b. The gas containing hydrogen generated from the object 7 passes through the second gas flow path 8b and reaches the vicinity of the exhaust port 10 without intersecting with the gas in the other gas flow path 8a.

  Regulators 11 and 12 as flow rate control means are arranged between the supply compressor 4 and the pipe joint 6 and between the recovery compressor and the pipe joint 6, respectively. Any flow control means may be used as long as gas flow control can be performed, and a needle valve, an orifice, a mass flow controller, or the like may be used. Alternatively, the gas flow rate may be controlled by changing the outputs of the gas supply means and the gas recovery means.

  A dissolved oxygen concentration meter 13 is inserted into the plating tank 1 to measure the dissolved oxygen concentration in the plating solution. This measured value is monitored by the control device 14, and the amount of air supplied from the outside is controlled by adjusting the opening degree of the regulators 11 and 12 by feedback control, and the dissolved oxygen concentration in the plating solution is adjusted. ing.

  By performing electroless copper plating in these configurations, plating with the same quality as the conventional plating can be performed while reducing the amount of formaldehyde and sodium hydroxide added.

  Electroless plating was performed in an electroless copper plating apparatus having the configuration shown in FIG. As an average of the time required for plating, the flow rate of the gas supplied from the supply compressor 4 and the recovery compressor 5 was a ratio of 1: 2, and the amount of air introduced from the outside was 1/3. In this state, plating equivalent to the conventional plating was possible in terms of plating speed and quality. In addition, the volatilization amount of formaldehyde was reduced by about 39%, and the life of the plating solution was extended. It should be noted that the plating is performed in a state where the flow rate of the gas supplied from the supply compressor 4 and the recovery compressor 5 is 1: 1 while the regulators 11 and 12 are fixed at a predetermined opening without operating the flow rate control means. However, the volatilization amount of formaldehyde was reduced by about 23%, and the life of the plating solution was extended.

  FIG. 2 is a view showing another example of the plating apparatus according to the present invention. The plating tank 1 is filled with an electroless copper plating solution mainly composed of copper sulfate, formaldehyde, sodium hydroxide, and a complexing agent, and foreign matter is removed by a circulation, a filtration mechanism and a temperature control mechanism (not shown). It is kept at a suitable temperature.

  The plating tank 1 can be blocked from the outside air, and the object 7 can be taken in and out from the lid 2. Inside the plating tank 1, the diffuser tubes 3a and 3b are arranged, and the diffuser tube to-be-plated object 7 is arranged so that air bubbles from both of the diffuser tubes are hit.

  Air sent from a supply compressor 4 as gas supply means is sent to the air diffusion pipe 3a. The gas sent from the recovery compressor 5 as a gas recovery means is sent to the air diffuser 3b. With this configuration, while supplying fresh air to the entire plating solution, the gas flow rate can be increased in the vicinity of the object 7 and the stirring effect can be increased. Although not performed in the present embodiment, it is also possible to adopt a configuration in which fresh air is intensively sent to a place where the plating solution is easily decomposed, such as the vicinity of the plating tank wall or the heating device.

  The gas bubbled into the plating solution from the air diffuser 3 reaches the gas flow path 8 and is supplied again to the plating solution from the air intake 9 through the recovery compressor 5. Moreover, the exhaust port 10 is installed above the intake port 9, and a light gas is discharged preferentially. Further, immediately above the object 7 to be plated, the gas flow path 8 is partitioned by a partition 18 as a gas blocking means to form a second gas flow path 8b. The gas containing hydrogen generated from the object 7 passes through the second gas flow path 8b and reaches the vicinity of the exhaust port 10 without intersecting with the gas in the other gas flow path 8a.

  Regulators 11 and 12 as flow rate control means are arranged between the supply compressor 4 and the pipe joint 6 and between the recovery compressor and the pipe joint 6, respectively.

  A dissolved oxygen concentration meter 13 is inserted into the plating tank 1 to measure the dissolved oxygen concentration in the plating solution. This measured value is monitored by the control device 14, the opening degree of the regulators 11 and 12 is adjusted by feedback control, the supply amount of fresh air is controlled, and the dissolved oxygen concentration in the plating solution is adjusted.

  When the electroless copper plating is performed in the above configuration, the plating speed, quality, etc. are the same as before even when the flow rate of the gas supplied from the supply compressor 4 and the recovery compressor 5 is 1: 3.5. Plating was possible. Further, the volatilization amount of formaldehyde was reduced by 54%, and the life of the plating solution was extended. The results of Example 1 and Example 2 are summarized as shown in FIG. 6, and the effect of reducing the volatilization amount was confirmed.

  FIG. 3 is a view showing an example of a plating apparatus according to the present invention. The plating tank 1 is filled with an electrolytic gold plating solution containing gold sulfite as a main component, and foreign matters are removed by a circulation, a filtration mechanism and a temperature adjustment mechanism (not shown), and the temperature is maintained at a temperature suitable for plating.

  The plating tank 1 can be blocked from the outside air, and the object 7 can be taken in and out from the lid 2. Inside the plating tank 1, an energization means (not shown) for an object to be plated, a counter electrode 17, and an air diffuser 3 as a ventilation means are arranged.

  Nitrogen sent from the nitrogen cylinder 15 and gas sent from the recovery compressor 5 as gas recovery means are mixed and introduced into the air diffusion pipe 3 by the pipe joint 6 as gas mixing means. Yes.

  The gas bubbled into the plating solution from the air diffuser 3 reaches the gas flow path 8 and is supplied again to the plating solution from the air intake 9 through the recovery compressor 5. Moreover, the exhaust port 10 is installed above the intake port 9, and discharges light gas preferentially. Moreover, the gas flow path 8 is partitioned immediately above the workpiece 7 to form a second gas flow path 8b. The gas containing hydrogen generated from the object 7 passes through the second gas flow path 8b and reaches the vicinity of the exhaust port 10 without intersecting with the gas in the other gas flow path 8a.

  Regulators 11 and 12 as flow rate control means are arranged between the nitrogen cylinder 15 and the pipe joint 6 and between the recovery compressor and the pipe joint 6, respectively.

  Further, an oxygen concentration meter 16 is inserted between the pipe coupling portion 6 and the diffuser tube 3 to measure the oxygen concentration in the gas. This measured value is monitored by the control device 14, and the opening amounts of the regulators 11 and 12 are adjusted by feedback control to control the supply amount of nitrogen from the cylinder, and the oxygen concentration in the gas blown into the plating solution is very small. It is adjusted to keep the density low.

  As a result of performing electrolytic gold plating in the configuration as described above, the plating speed, quality, and the like were equal to or higher than those of the prior art, even though the required nitrogen gas flow rate was about ½ of the conventional one.

It is a figure which shows schematic structure of the electroless-plating apparatus which concerns on one embodiment of this invention. It is a figure which shows schematic structure of the electroless-plating apparatus which concerns on other embodiment of this invention. It is a figure which shows schematic structure of the electroplating apparatus which concerns on other embodiment of this invention. It is a figure which shows schematic structure of the conventional electroless-plating apparatus. It is a figure which shows schematic structure of the conventional electrolytic plating apparatus. It is a table | surface which shows the volatilization amount reduction effect in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plating tank 2 Lid 3 Air diffuser 3a 1st air diffuser 3b 2nd air diffuser 4 Supply compressor 5 Recovery compressor 6 Pipe connection part 7 To-be-plated object 8 Gas flow path 8a First gas flow path 8b Second 9 Gas intake port 10 Gas exhaust port 11 Regulator 12 Regulator 13 Dissolved oxygen meter 14 Control device 15 Nitrogen cylinder 16 Oxygen concentration meter 17 Counter electrode 18 Partition 101 Plating tank 102 Lid 103 Air diffuser tube 104 Supply compressor 107 110 Exhaust port 112 Regulator 113 Dissolved oxygen meter 115 Nitrogen cylinder

Claims (9)

  A method for producing a plated product, comprising collecting a gas discharged from a plating solution surface in a plating tank and supplying the gas as a stirring gas for the plating solution in the plating tank. A gas flow path for allowing the gas discharged from the plating solution surface in the plating tank to pass;
A gas recovery means connected to the gas flow path for recovering the gas in the gas flow path;
A plating apparatus comprising: a ventilation means for supplying the gas recovered by the gas recovery means into the plating solution.   The plating apparatus according to claim 2, further comprising an outside air shielding unit that is provided above the plating solution surface portion and suppresses the outside air from being mixed into the gas flow path.   The plating according to claim 2, further comprising a gas shielding means that is provided above the plating solution surface portion and suppresses mixing of gas discharged from a portion directly above the object to be plated on the plating solution surface portion into the gas flow path. apparatus. The gas flow path includes an exhaust port for discharging a part of the gas in the gas flow path,
The plating apparatus of Claim 2 arrange | positioned above the gas intake port of the gas collection | recovery means connected to the said gas flow path.   The plating apparatus according to claim 2, further comprising gas supply means for supplying a gas other than the gas recovered by the gas recovery means into the plating tank.   7. A gas mixing means for mixing a gas other than the gas recovered by the gas recovery means and a gas supplied from the gas recovery means to communicate with the ventilation means is provided. Plating equipment   The plating apparatus according to claim 6 or 7, further comprising a flow rate adjusting unit capable of independently controlling a flow rate of the gas from the gas supply unit and the gas recovery unit. Gas concentration measuring means for measuring at least one of the concentration of the gas component in the gas flow path and the concentration of the gas component dissolved in the plating solution with respect to one or more gas components contained in the gas. The plating apparatus according to claim 2, wherein:

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