JPS63484A - Method and apparatus for regenerating electroless copper plating solution - Google Patents

Abstract

PURPOSE:To efficiently recover an electroless copper plating soln. by placing a chamber between a plating soln. regenerating chamber and an anode chamber and keeping a soln. in the placed chamber alkaline so as to prevent deterioration in the function of an anion exchange membrane by the deposition of a copper ion chelating agent. CONSTITUTION:An aqueous NaOH soln. 11, 14 is poured into a cathode chamber 30 and a second intermediate chamber 40b and an aqueous H2SO4 soln. 12 is poured into an anode chamber 50. An exhausted electroless copper plating soln. 13 is then poured into a first intermediate chamber 40a and DC voltage is applied between the cathode 1 and anode 2 from a DC power source E to regenerate the plating soln. 13. The NaOH soln. 11 in the cathode chamber 30 and the NaOH soln. 14 in the second intermediate chamber 40b are circulated with pumps P1, P2 during dialysis.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method and apparatus for regenerating electroless copper plating solution,
In particular, the present invention relates to a method and apparatus for regenerating an electroless copper plating solution for removing harmful ions that interfere with plating reactions in the electroless copper plating solution.

[Conventional technology]

Copper ion, copper ion chelating agent, copper ion reducing agent,
PL (electroless copper plating solution containing alkali metal hydroxide as a regulator as a product accumulates harmful ions that interfere with the plating reaction with long-term use. Generally, to replenish copper ions, Formaldehyde is used as a reducing agent for copper sulfate and copper ions.

Since sodium hydroxide is used as a PL+ regulator, harmful ions such as sulfate ion, which is the counteranion of copper ion, formate ion, which is an ion produced by the oxidation reaction of formaldehyde, and sodium ion, which is an alkali metal ion, accumulate. .

When these ions accumulate and increase, the plating solution becomes unstable and causes decomposition of the plating solution.

It also reduces the mechanical properties of the plating film.

A method and apparatus for removing these accumulated ions in a plating solution and regenerating the plating solution are disclosed in U.S. Patent Nos. 4 and 2.
89,597 (September 15, 1981). According to this patent, one electrodialysis cell can be
Anode chamber by two anion exchange resin membranes.

Divided into a plating solution regeneration chamber and a cathode chamber, each containing a sulfuric acid aqueous solution, a plating solution to be regenerated, and a sodium hydroxide aqueous solution.
Electrodes are immersed in the anode and cathode chambers, and a DC voltage is applied between the two electrodes to remove sulfate and formate ions accumulated in the plating solution in the plating solution regeneration chamber and regenerate the plating solution. Ru.

[Problem that the invention seeks to solve]

In the conventional regeneration technology described above, looking at the electrode reactions at the anode and cathode, the following reactions also occur at the anode, but when formate ions enter the anode chamber.

At the cathode HzO" e-→OH-" Hz ↑.

Therefore, hydrogen ions are generated in the anode chamber, and hydroxide ions are generated in the cathode chamber. During electrodialysis, hydroxide ions are responsible for the transfer of charge from the cathode chamber to the plating solution regeneration chamber, and approximately the same amount of hydroxyl ions as those generated by the electrode reaction at the cathode are transferred. In addition, the substances responsible for the transfer of charge from the plating solution regeneration chamber to the anode chamber are mainly sulfate ions and formate ions, with only a few copper ion chelate compounds, copper ion chelating agents, and anionic additives. agents, hydroxide ions, etc. Therefore, the concentration of hydroxide ions in the solution in the cathode chamber hardly changes, but the concentration of hydrogen ions in the solution in the anode chamber increases. By the way, as mentioned above, sulfate ions exist as anions in the plating solution.

There are formate ions, copper ion chelate compounds, copper ion chelating agents, anionic additives, hydroxide ions, etc. However, when an aged plating solution is regenerated in a batch manner, for example, sulfate ions and Because the amount of formate ions is overwhelmingly larger than other anions, when electrodialysis is performed, sulfate ions and formate ions mainly pass through the anion exchange resin membrane from the plating solution in the plating solution regeneration chamber to the solution in the anode chamber. However, long-term regeneration progresses in the removal of sulfate and formate ions, and when the concentration of these ions decreases, other anions such as copper ion chelating compounds, copper ion chelating agents, and anions Chemical additives, hydroxyl ions, etc. are involved in migration.

In addition, during continuous regeneration in which electrodialysis is performed simultaneously with plating, there are almost no formate ions in the plating solution when it is prepared, but the concentration of copper ion chelating compounds and copper ion chelating agents is In many cases, the concentration of harmful ions such as sulfate ions and formate ions can be removed selectively only after 1.2 cycles of plating.
If the accumulation rate and removal rate of harmful ions are not well balanced, copper ion chelating compounds, copper ion chelating agents, anionic additives, hydroxide ions, etc. Components necessary for the plating reaction, such as the following, may also be removed.

Further, when replenishing copper ions as a chelate compound of copper ions, the chelating agent of copper ions will be accumulated in the plating solution like harmful ions.

For example, when ethylenediaminetetraacetic acid (hereinafter referred to as EDTA) is used as a chelating agent for copper ions.

In the plating solution, a chelate compound is created with copper ions (E
DTA-Cu)", (EDTA((ltl)Cu)'
It exists in the form of ``'', and the rest exists in the form of EDTA'-. When these components are involved in movement due to the reasons mentioned above when electrodialysis is performed, the concentration of hydrogen ions is high in the anode chamber, so EDTA'- becomes EDTA-4H, and the connection between the plating solution regeneration chamber and the anode chamber is It adheres to the anion exchange resin membrane placed in the interchamber, causing a decline in the function of the anion exchange resin membrane.

In addition, when cyanide compounds are used as additives,
If cyanide ions move into the anode chamber, cyanide gas generation may occur, which is very dangerous.

Moreover, sodium ions cannot be removed by the above-mentioned conventional techniques.

An object of the present invention is to provide an electroless copper plating solution regeneration device and a method for regenerating the same, which eliminate the drawbacks of the prior art.

[Differences between the invention and the prior art]

In contrast to the conventional electroless copper plating solution regeneration technology mentioned above,
The present invention provides one chamber between the plating solution regeneration chamber and the anode chamber, and by keeping the solution in the chamber alkaline, it prevents the deterioration of the function of the anion exchange resin membrane due to the adhesion of a copper ion chelating agent. .

Even in a plating solution containing a cyanide compound, no cyan gas is generated even if cyanide ions move, and furthermore, it has the original content of being able to remove alkali metal ions from the plating solution.

[Means for resolving the gap]

The present invention uses one anion exchange resin membrane placed in the center and a pair of cation exchange resin membranes placed opposite to each other with the anion exchange resin membrane in between to form a cathode chamber, a first intermediate chamber, and a second intermediate chamber. Copper ions, a chelating agent for copper ions, a reducing agent for copper ions, and an alkali metal hydroxide as a pHau agent are mainly contained in the first intermediate chamber of the electrodialysis tank, which is divided into four chambers: a chamber and an anode chamber. An electroless copper plating solution containing a stabilizer that maintains the stability of the plating solution and an additive that improves the physical properties of the plating film is filled, and the cathode chamber and the second intermediate chamber are filled with an alkaline electrolyte solution. Then, fill the anode chamber with an acidic electrolyte solution.

A solution circulation mechanism provided between the cathode chamber and the second intermediate chamber circulates the solution in both chambers, and after immersing the cathode electrode and the anode electrode in the cathode chamber and anode chamber, respectively, a direct current is applied between the two electrodes. An electroless copper plating solution that removes counteranions of copper ions, ions produced by the oxidation reaction of a reducing agent, and alkali metals by applying a voltage. How to play and.

A cathode chamber, a first intermediate chamber, a second intermediate chamber, an electrodialysis tank partitioned into four anode chambers, and a mechanism for circulating the solution in the cathode chamber and the solution in the second intermediate chamber between the cathode chamber and a second intermediate chamber;
The electroless copper plating solution regeneration apparatus is characterized in that a cathode electrode is disposed in the cathode chamber and an anode electrode is disposed in the anode chamber, and a DC power source is provided for applying a DC voltage between the two electrodes.

[Principle/effect]

The cathode chamber and the second intermediate chamber are filled with an alkaline electrolyte solution, such as an aqueous sodium hydroxide solution, and the first intermediate chamber is filled with a regenerated electroless copper plating solution using EDTA as a chelating agent for copper ions, or a cyanide compound. The anode chamber is filled with an electroless copper plating solution containing 1, and the anode chamber is filled with an acidic electrolyte solution 1, such as an aqueous sulfuric acid solution. A mechanism for circulating the solutions in both chambers, such as a circulation pipe and a pump, is provided between the cathode chamber and the second intermediate chamber to circulate the solutions in both chambers.

An electrode, for example, a platinum-plated titanium electrode, is immersed in each of the solutions in the cathode chamber and the anode chamber, and a DC voltage is applied between the two electrodes. Hydroxyl ions are generated in the solution in the cathode chamber by an electrode reaction. Between the cathode chamber and the first intermediate chamber, sodium ions are transferred from the plating solution in the first intermediate chamber to the solution in the cathode chamber, and between the first intermediate chamber and the second intermediate chamber, the plating solution in the first intermediate chamber is transferred to the solution in the cathode chamber. Mainly sulfate ions and formate ions move from the solution to the solution in the second intermediate chamber. Furthermore, plating solutions that use EDTA as a chelating agent for copper ions use EDTA.

(EDTA-CoF2- also moves. In a plating solution containing a cyanide compound, cyanide ions also move. In the anode chamber, hydrogen ions are generated by an electrode reaction, and approximately the same amount of hydrogen ions as the generated hydrogen ions are transferred to the anode. The solution in the chamber moves to the solution in the second intermediate chamber.A mechanism is provided between the cathode chamber and the second intermediate chamber to circulate the solution in both chambers. The hydroxide ions generated in the anode chamber and the hydrogen ions moving from the solution in the anode chamber to the solution in the second intermediate chamber cause a neutralization reaction, and the solution in the second intermediate chamber is kept alkaline. EDTA moving from the plating solution in the chamber to the solution in the second intermediate chamber does not adhere to the anion exchange resin membrane disposed between the first intermediate chamber and the second intermediate chamber, and does not reduce its function. The cyanide ions moving from the plating solution in the first intermediate chamber to the solution in the second intermediate chamber can safely regenerate the plating solution without turning into cyan gas.Furthermore, sodium in the plating solution can also be removed.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

(Example 1) FIG. 1 is a sectional view of an electroless copper plating solution regenerating apparatus showing an example of the present invention. In the figure, 10 is an electrodialysis tank made of synthetic resin such as polypropylene.
Inside is cation exchange resin membrane 20a, 20c, ¥3
．． The ion exchange resin membrane 20b is arranged to form the cathode chamber 30, the first
It is partitioned into four rooms: an intermediate chamber 40a, a second intermediate chamber 40b, and an anode chamber 50. Cathode chamber 30 and second intermediate chamber 40b
A distribution pipe M60 for circulating the solution in the cathode chamber 30 and the solution in the second intermediate chamber 40b is provided between the pumps Pi and P2.
Circulate the solution. E is a DC power supply connected by a lead wire 3 led out from a cathode electrode 1 using, for example, a platinum-plated titanium electrode and an anode electrode 2 such as a platinum-plated titanium electrode.

Next, a method for regenerating an electroless copper plating solution according to the present invention will be explained with reference to FIG. First, the cathode chamber 30 and the second intermediate chamber 40b
A 4 g H1 aqueous sodium hydroxide solution 11°14 is placed in the anode chamber 50, and a 10 g/Q sulfuric acid aqueous solution 12 is placed in the anode chamber 50.

Then p
1 (=12) of the pseudo-aged electroless copper plating solution 13 is put into the first intermediate chamber 40a.

A DC voltage was applied between the cathode electrode 1 and the anode electrode 2 using a DC source E, and regeneration was performed for 18 hours.

During dialysis, the sodium hydroxide aqueous solution 11 in the cathode chamber 30 and the sodium hydroxide aqueous solution 14 in the second intermediate chamber 40b were circulated by pumps Pi and P2. Note that the cation exchange resin membranes 20a and 20c, the anion exchange resin membrane 2
0b each has a cation exchange resin membrane C manufactured by Tokuyama Soda ■.
LE-E and anion exchange resin membrane ACLE-5P were used, and the contact area of these ion exchange resin membranes with the solution in each chamber was 100 d, and the electrolytic current density was 30 mA/a (in each chamber of the electrodialysis tank 10). The capacity of was set to 1.5Q.The hydroxide ion concentration of the sodium hydroxide aqueous solution 14 in the second intermediate chamber 40b before the start of regeneration and after the end of regeneration was analyzed and found to be O, Imo.
It was confirmed by Q/Q that there was no change and the alkalinity was maintained, and no EDTA was observed to adhere to the anion exchange resin membrane 20b. In addition, when the sodium ion concentration of the sodium hydroxide aqueous solution 11 in the cathode chamber 30 was analyzed, it was 0.1 moQ/Q before the start of regeneration, but it was 0.77 moQ#t after the end of regeneration, and the sodium ions were removed. It was confirmed that

(Embodiment 2) FIG. 2 shows a system flow of Embodiment 2 of the present invention.

The electroless copper plating solution regeneration apparatus of Example 1 described above was connected to the plating bath 70 via pumps P3 and P4 and heat exchangers 80a and 80b to perform continuous regeneration.

Similarly to the regeneration method of Example 1 described above, a 4 g/Q aqueous sodium hydroxide solution is placed in the cathode chamber 30 and the second intermediate chamber 40b, and a log/fl aqueous sulfuric acid solution is placed in the anode chamber 50. Copper sulfate Log/Q, ethylenediaminetetraacetic acid 40g
#l, 20 IQ of sodium cyanide was added to an electroless copper plating solution of pH=12 containing 2 g IQ of formaldehyde.

It was put into the plating tank 70 and the first intermediate chamber 40a, and regeneration was performed simultaneously with plating. During plating, pump PL, P2
The solution in the cathode chamber 30 and the solution in the second intermediate chamber 40b were circulated. Further, the plating solution in the plating tank 70 is pumped up by the pump P3, cooled by the heat exchanger 80a, and put into the first intermediate chamber 40a, and the plating solution in the first intermediate chamber 40a is pumped up by the pump P4, heated by the heat exchanger 80b, and then plating It was placed in a tank 70 and constantly circulated. The capacity of the plating tank 70 is 2Q, the plating temperature is 70℃, and the load factor is 10.
0a&/fi, one cycle was performed by depositing up to 351 m, and three cycles were performed. PHy copper, formaldehyde, and cyanide were analyzed and replenished every hour. The copper replenisher is copper sulfate 150g #I.

An alkaline aqueous solution containing 175 g/Q of ethylenediaminetetraacetic acid, formaldehyde replenisher is 37% formalin, PL (a preparation is 28% sodium hydroxide aqueous solution).

The cyanide replenisher was an alkaline aqueous solution containing 40 g IQ of sodium cyanide. The conditions for dialysis are that the electrolytic current density is l
omA/cJ, dialysis temperature is 25-30℃, capacity of each chamber of electrodialysis tank IO is 1.5Q, cation exchange resin membrane 20
a, 20c, and the anion exchange resin membrane 20b are cation exchange resin membrane CLE-E and anion exchange resin membrane ACLE-5P manufactured by Tokuyama Soda ■, respectively, and these ion exchange resin membranes and the solution in each room are used. The contact area with is 100aJ
And so.

During the regeneration, the hydroxide ion concentration of the solution in the second intermediate chamber 40b was analyzed every hour, and it remained alkaline with no change at approximately O. was not observed, nor was the generation of cyan gas confirmed.

〔Effect of the invention〕

As explained above, the present invention is an electroless copper plating solution that uses a chemical that precipitates in an acidic solution such as ethylenediaminetetraacetic acid as a chelating agent for copper ions, or an electroless copper plating solution that contains a cyanide compound. When regenerating alkali metals, it is possible to prevent the deterioration of the function of the anion exchange resin membrane due to the adhesion of copper ion chelating agents, and it is possible to safely perform long-term regeneration without generating cyan gas. It also has the effect of removing sodium ions.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of an electroless copper plating solution regeneration apparatus according to Examples 1 and 2 of the present invention. DESCRIPTION OF SYMBOLS 1... Cathode electrode, 2... Anode electrode, 3... Lead wire, 10... Electrodialysis tank, -11, 14... Sodium hydroxide aqueous solution, 12... Sulfuric acid aqueous solution, 13...・・・
Electroless copper plating solution, 20a, 20C...Cation exchange resin membrane, 20b...Anion exchange resin membrane, 30.
...Cathode chamber, 40a...First intermediate chamber, 40b...
Second intermediate chamber, 50... Anode chamber, 60... Piping, 70
...Plating tank, 80a, 80b, heat exchanger, PI
, P2. P3. P4-...Pump, E...DC power supply

Claims (2)

[Claims] (1) A cathode chamber, a first intermediate chamber, a second Copper ions, a chelating agent for copper ions, a reducing agent for copper ions, and an alkali metal hydroxide as a pH adjusting agent are placed in the first intermediate chamber of the electrodialysis tank, which is divided into four chambers: an intermediate chamber and an anode chamber. The cathode chamber and the second intermediate chamber are filled with an electroless copper plating solution containing a stabilizer that maintains the stability of the plating solution and an additive that improves the physical properties of the plating film, and an alkaline electrolyte solution is filled in the cathode chamber and the second intermediate chamber. The anode chamber is filled with an acidic electrolyte solution, and the cathode chamber and the second
A solution circulation mechanism provided between the intermediate chamber circulates the solution in the cathode chamber and the solution in the second intermediate chamber, and after immersing the cathode electrode and the anode electrode in the cathode chamber and the anode chamber, respectively, A direct current voltage is applied between the electroless copper plating solution to remove counter anions of copper ions, ions produced by the oxidation reaction of the reducing agent, and alkali metal ions, which are harmful ions of the plating reaction in the electroless copper plating solution. Method for regenerating electrolytic copper plating solution. (2) A cathode chamber, a first intermediate chamber, a second It has an electrodialysis tank partitioned into four chambers, an intermediate chamber and an anode chamber, and a mechanism is provided between the cathode chamber and a second intermediate chamber to circulate the solution in the cathode chamber and the solution in the second intermediate chamber. An apparatus for regenerating an electroless copper plating solution, characterized in that a cathode electrode is disposed in the cathode chamber, an anode electrode is disposed in the anode chamber, and a DC power supply is provided for applying a DC voltage between the two electrodes.