JPS59116364A - Control method of electroless copper plating bath - Google Patents

Abstract

PURPOSE:To enable the use of a replenishing soln. having a high concn. of Cu ion and to improve the quality of an electroless Cu plating film by heating the replenishing soln. of Cu ion consumed in an electrolyte during the operation of electroless Cu plating to a specific temp. thereby replenishing said ion. CONSTITUTION:A Cu plate of which the surface is preliminarily catalyzed by Pd, etc. is dipped in an electroless Cu plating soln. contg. copper sulfate as a Cu ion source, formaldehyde as a reducing agent for Cu ion and NaOH as a pH adjusting agent, whereby Cu is deposited on the surface by electroless plating. The concn. of the copper sulfate, formaldehyde and NaOH in the plating soln. decreases with progression of the plating reaction and are therefore replenished respectively. The aq. copper sulfate soln. in this case is heated to 70-90 deg.C and is replenished as the aq. soln. having the higher concn. of copper sulfate, whereby the concn. of the Cu ion in the plating soln. is easily maintained at the correct concn. and the electroless plating film having excellent quality is formed.

Description

[Detailed Description of the Invention] [Technical Field to Which the Invention Pertains] The present invention relates to a method for managing non-screening steel plating, and more specifically to a method for recharging steel ions in a spent electroless copper plating bath.

[Conventional technology 01''8 and its problems] PicfiW steel plating is a chemical process in which the main mother ion in the bath liquid is reduced and precipitated on the catalytically active surface using a reducing agent. It is widely used for printed wiring.In order to obtain a plating film with good properties in such a plating bath, the concentration of each component in the plating bath, especially the concentration of the main component, must be adjusted to an appropriate concentration range. need to be maintained.

It is thought that the reaction of linear equation (1) is responsible for the precipitation of copper in electroless copper plating.

Cu"+2HCHO+40H-+ CuO+Ht+2 Hz O+2 HC00-fl) This reaction is a catalytic reaction, and the precipitated copper itself further acts as a catalyst for this reaction. Therefore, more copper is automatically deposited on top of the precipitated copper. The thickness increases and plating progresses.

In the electroless copper plating method, unlike the electrolytic copper plating method, there is no replenishment of copper ions by anodic dissolution, so the copper ion concentration in the bath gradually decreases due to copper precipitation. Furthermore, as is clear from equation (1), the concentrations of formaldehyde and sodium hydroxide also decrease.

Therefore, it is the main component of chemical steel plating solutions. In order to always maintain the concentrations of copper ions, formaldehyde, and sodium hydroxide within the normal concentration range, it is necessary to supplement the light of these three components in the plating solution.

The replenishment method is to analyze the m1 degree of each of the single ions, formaldehyde, and aqueous sodium in the plating solution and replenish the deficiencies. It is common to use a bath solution. The reason why a concentrated bath solution is used is that it is necessary to suppress an increase in the amount of plating solution that occurs due to replenishment. The replenishment method is one of the plating conditions.

It changes depending on the plating temperature. When plating at room temperature, most of the water evaporates from the plating tank, so after pumping out the plating solution,
(Ti light is used.Therefore, there is a problem that the expensive plating solution must be disposed of.On the other hand, high temperature (
In LiA, which is plated at a temperature (generally below 80°C), the amount of water evaporated increases, so the pumping h# tends to decrease.

However, when the plating speed is increased, the amount of replenisher still exceeds the amount of evaporation, making it necessary to discard the plating solution. by the way,
In particular, the value of acid copper, which is confirmed as a copper salt, is V at finger temperature.Is the solubility in water small? Bring it into the plating solution. In order to solve this problem of increasing the amount of liquid due to supplementary light, for example, Japanese Patent Publication No. 53-6934 proposes a method of adding copper salt as the main component in the form of powder or slurry. has been done.

However, this method has the drawback that the replenishment operation does not proceed smoothly because powder is used, and even though the powder is used to supplement the light, locally high concentration areas occur, which can cause the plating solution to become unstable and decompose. there were.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems and provide a copper ion replenishment method that suppresses an increase in the amount of liquid when supplementing steel ions to a high-speed electroless copper plating bath.

[Summary of the invention]

In the method of replenishing a tome-free steel plating bath comprising a C1 steel ion source, a reducing agent, a complexing agent, and a PH control agent with ion, by heating the replenishing solution to 70°C or higher,
It is characterized by reducing the concentration of copper ions in the replenisher.

In the copper ion replenisher of the present invention, conventionally used salts can be used as the 0-salt.

The temperature of the replenisher according to the present invention is in the range of 70°C or more and 90°C or less, preferably 75°C or more and 85°C or less.

Another reason for this is that below 70°C, the concentration of the copper salt is low and there is little effect in suppressing the increase in liquid volume in the plating bath due to replenishment.
This is because local heating causes problems such as the plating bath decomposing.

By using the paulownia ion replenisher of the present invention, the amount of steel ion replenisher (4) can be significantly reduced, and the amount of solution required for high-speed non-blocking copper plating bath can be reduced, thereby reducing costs. This contributes to solving the waste liquid problem.

[Embodiments of the invention]

Example 1 J'? E d l turn - Immerse the copper plate in 10% water] sodium ablation solution for 30 seconds at room temperature, wash with water, then continue to 10% nitric acid - In the evening? +: The surface of the body plate was cleaned by immersing it in warm water for 5 seconds and washing with water. Next, the copper foil was treated with tin chloride (JI) 50 g/i hydrochloric acid 1 (J
It was immersed for 2 minutes in a bath solution with the following composition: m (171 water, balance:
The sample was immersed in a solution having a composition of 0 rnl/1 water and the remainder for 1 minute, and then washed in running water for 1 minute. After that, sulfuric acid @ (5 aqueous phase) 0.03 mol N,
N,N',N-tetrakis-0,045 mol(euhydroxypropyl)ethylenediaminevalaformaldehyde 0.1 molSodium hydroxide
Bone 2.2'-dipyridyl with PI of 12.3
Plating bath 201 with a composition of 20 mfl/12-mercaptobenzothiazole l rng/l water and the remainder! A 1 mm thick T plate catalyzed as described above was immersed in this bath so that the plating area per layer was 2.5 dm2.

Plating was performed for 4 hours. This is 1 cycle, total 5
Repeated over cycles. The plating conditions are as follows:
A plating temperature of 5° C. and a plating bath P fi of 12.3 were used. At this time, the deposition rate was 10 μm/h.

In order to maintain and control each component of the plating bath at a constant level, use a plating bath conditioner) and use the copper ion replenisher, sodium hydroxide surface brightening solution, and formaldehyde brightening solution shown in Table 1. It was supplemented with light.

Figure 1 shows the relationship between the four liquids of sentinel ion + iti original solution supplemented with light at this time and the number of cycles.

Comparative Example 1 Plating solution replenishment was carried out in the same manner as in Example bIIiI+01 except that the replenisher composition shown in Table 1 Comparative Example was used.

At this time, the relationship between the application of the copper ion brightening solution that was illuminated for 4 iti and the number of cycles is also shown in FIG.

As shown in Fig. 1, in the comparative example, copper ion replenishment mydriasis was 206 after 5 cycles of plating, which is almost the same as the amount of plating bath at the time of bath preparation, whereas in the example of the present invention, the amount of plating bath was approximately 101 and 50. decrease to a certain degree.

〔Effect of the invention〕

As is clear from the above description and examples, the copper ion replenisher of the present invention can suppress an increase in the amount of plating bath when supplementing paulownia ions to a surface speed non-coating steel plating bath. I can do it,
It also has many advantages, such as facilitating the continuous operation of the plating process and reducing the cost required for waste liquid treatment.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the invention in detail. Representative patent attorney Kensuke Chika (d = 1 person) No. 1
One size picture,

Claims (1)

[Claims] The light solution is heated and added to an electroless copper plating bath consisting of a copper ion source, a reducing agent, a complexing agent, and a PH adjusting agent, using a VC that supplements steel ions. %
Characteristic electroless copper plating bath management method.