JPH0323634B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a chemical copper plating bath that provides a chemical copper plating film with high mechanical properties such as elongation and tensile strength, and in particular those mechanical properties are improved by heat treatment. Conventional technology and its problems Traditionally, in the production of printed wiring boards using the full additive method, after forming a circuit with a chemical copper plating film on an adhesive-coated laminate, the chemical copper plating film and the adhesive-coated laminate are formed. Heat treatment (usually at about 150°C) is carried out to improve the adhesion with other materials. Various baths have been proposed as chemical copper plating baths used in the production of printed wiring boards by such fully additive methods, but the chemical copper plating film obtained from the conventional chemical copper plating baths is Although the above-mentioned heat treatment improves the elongation of the copper film, there is a problem that the tensile strength decreases, and for this reason, the quality of printed wiring boards produced by the fully additive method in which circuits are formed using this chemical copper plating film cannot be fully satisfied. It was hot. SUMMARY OF THE INVENTION In view of the above circumstances, the present inventors have conducted intensive research on a chemical copper plating bath that can form a chemical copper plating film that provides good mechanical properties and does not deteriorate in mechanical properties, especially through heat treatment. As a result, copper ions and
In a chemical copper plating bath containing a complexing agent for complexing copper ions and a reducing agent, ethylenediaminetetraacetic acid or its salt is used as the complexing agent, and ethylenediamine and α,α′-
It has been found that a bath to which dipyridyl is added achieves the above objective. That is, the plated film obtained from a chemical copper plating bath in which ethylenediaminetetraacetic acid or its salt (hereinafter referred to as EDTA) is used as a complexing agent and ethylenediamine and α,α'-dipyridyl are added has low elongation and tensile strength. Not only did it have good mechanical properties, but it also had an excellent appearance.Moreover, when this plated film was heat treated, its tensile strength and elongation improved. As mentioned above, the elongation of plating films from conventional chemical copper plating baths improves through heat treatment, but the tensile strength decreases; Although it was thought that heat treatment would reduce the
A new finding that the elongation and tensile strength of plating films made from chemical copper plating baths using EDTA as a complexing agent and adding ethylenediamine and α,α'-dipyridyl are unexpectedly improved by heat treatment. This is what I got. Furthermore, it has been found that when α,α'-dipyridyl is used in combination with ethylenediamine, the concentration range in which α,α'-dipyridyl can be used is expanded. In other words, when α,α'-dipyridyl is added to conventional chemical copper plating baths in an amount of 0.00025 mol or more, the precipitation rate decreases, and a film of cuprous oxide is formed on the plating film, which significantly deteriorates its physical properties. Therefore, α,α′-dipyridyl is usually 0.00015 to 0.00025
The problem was that the range of concentration used was narrow, as it was used in a concentration range of mol/molar. However,
When α,α′-dipyridyl is used in combination with ethylenediamine, the upper limit of its usage concentration range increases, e.g.
The present invention was made based on the unexpected discovery that it can be used without any problem even at a concentration of about 0.025 mol/mol. The present invention will be explained in more detail below. Structure of the Invention The chemical copper plating bath according to the present invention includes copper ions,
As a complexing agent for complexing copper ions, it contains ethylenediaminetetraacetic acid or its salt in an amount equal to or more than the copper ion, a formaldehyde reducing agent, ethylenediamine, and α,α′-dipyridyl. . Here, copper ions are supplied by copper sulfate, etc., which give divalent copper ions, and the concentration of copper ions is from 0.01 to
It is preferably 1 mol/, particularly 0.02 to 0.5 mol/. Further, as the copper complexing agent, ethylenediaminetetraacetic acid or its salt is used as described above, and its concentration is equimolar to or higher than that of copper ions. Further, in the present invention, formaldehydes such as formaldehyde are used as the reducing agent, and the concentration thereof is preferably 0.02 to 1 mol/, particularly 0.05 to 0.5 mol/. In addition to the above components, ethylenediamine is added to the chemical copper plating bath of the present invention. In this case, ethylenediamine alone can act as a complexing agent for the copper ions, but in the presence of the above-mentioned copper ion complexing agents, that is, EDTA, it essentially acts as a copper ion complexing agent. It doesn't work. Here, the amount of ethylenediamine used as an additive is not particularly limited, but it is preferably 0.001 to 0.5 mol/, particularly 0.005 to 0.1 mol/. In this case, ethylenediamine can be added in an amount of 0.002 to 2 mol per 1 mol of the reducing agent (formaldehyde), and even if the amount used is less than 0.1 mol per 1 mol of the reducing agent (formaldehyde), the effect is sufficient. . The chemical copper plating bath of the present invention further contains α,α′-dipyridyl, and as mentioned above,
By adding ethylenediamine and α,α'-dipyridyl together to a chemical copper plating bath using EDTA as a complexing agent, a chemical copper plating film whose tensile strength improves through heat treatment can be obtained for the first time. Furthermore, the range of concentrations in which α,α'-dipyridyl can be used can be expanded. On the other hand, even when cyanogens, which are conventionally known as stabilizers for chemical copper plating baths like α,α'-dipyridyl, are used in combination with ethylenediamine, the tensile strength of chemical copper plating films due to heat treatment increases. The purpose of the invention is not achieved. In this case, the amount of α,α′-dipyridyl used is not necessarily limited, but is 0.00001 to 0.025 mol/particularly
The amount is preferably 0.00005 to 0.01 mol/. The chemical copper plating bath of the present invention contains the above-mentioned copper ions, EDTAs, formaldehydes, ethylenediamine and α,α'-dipyridyl as essential components, and further contains various other components as necessary. For example, compounds that form addition products with formalin, stabilizers such as cyanides, ferrocyans, and the like may be added. The chemical copper plating bath of the present invention is preferably alkaline, particularly at pH 11 to 13.5. The method of using the chemical copper plating bath according to the present invention is the same as that of a normal chemical copper plating bath, in which the object to be plated is pretreated by a conventional method and then immersed in the bath. The plating temperature is preferably room temperature to 80°C, particularly 45 to 75°C. Further, the plating time is appropriately set depending on the required film thickness, the deposition rate of the plating bath, etc. The deposition rate of the chemical copper plating bath of the present invention can be controlled in various ways by changing the bath composition, plating temperature, etc., but it is generally preferable to control it within the range of 1 to 6 μm/h. There are no particular restrictions on the objects that can be plated using the plating bath of the present invention, but substrates for producing printed wiring boards, plastic molded products, ceramics, etc. that have been pretreated by conventional methods can be suitably plated. It is particularly effective for forming circuits on printed wiring boards using the full additive method, and for plating parts that require heat treatment. In this case, it is preferable that the parts plated with the plating bath of the present invention be subjected to heat treatment as a post-treatment.
This makes it possible to improve the elongation and tensile strength of the chemical copper plating film compared to the state in which it is deposited. Note that the heat treatment conditions are not necessarily limited, but the heat treatment temperature can be 50 to 900°C, especially 100 to 300°C, and the heat treatment time varies depending on the heat treatment temperature, etc., and is preferably 0.5 to 24 hours or more. ~3 hours, for example at 50℃
If the temperature is 600°C for 24 hours or more, it can be about a few minutes. Note that the atmosphere is not limited either, and any atmosphere such as a normal atmospheric atmosphere (oxidizing atmosphere), a reducing atmosphere, an inert gas atmosphere, a vacuum atmosphere, etc. can be adopted. Effects of the Invention As explained above, the chemical copper plating bath of the present invention has excellent mechanical properties such as elongation and tensile strength, has a good appearance, and has improved elongation and tensile strength through heat treatment. A chemical copper plating film can be obtained. Furthermore, the controlled concentration of α,α'-dipyridyl can be expanded. EXAMPLES Hereinafter, the present invention will be specifically explained by showing examples and comparative examples, but the present invention is not limited to the following examples. Examples and Comparative Examples A chemical copper plating bath with the following composition was manufactured, and a stainless steel plate (5 x 10 cm) degreased by a conventional method and catalyzed with an acid-activated catalyst solution containing palladium ions was plated under the following plating conditions. Then, a plating sample was created. Note that the plating film thickness was 30 μm.

[Table] Next, the elongation and tensile strength of the copper-plated foil of the above-mentioned plated sample were measured, and the results shown in Table 1 were obtained. Further, each plated sample was placed in a constant temperature dryer and heat treated at 160°C for a predetermined time, and then elongation and tensile strength were measured. FIG. 1 shows the results of a flash sample obtained using the bath of the example, and FIG. 2 shows the results of a flash sample obtained using the bath of the comparative example. Furthermore, after each plated sample was heat treated at various temperatures for 3 hours, the elongation and tensile strength were measured.
FIG. 3 shows the results of the plating samples from the bath of the example, and FIG. 4 shows the results of the plating sample from the bath of the comparative example. In addition, in the drawing, E is elongated,
UTS stands for tensile strength. Here, elongation and tensile strength were each measured using a Shimadzu tensile tester MP100.

[Table] From the results shown in Table 1 and FIGS. 1 to 4, it was found that the elongation and tensile strength of the fried film obtained from the bath of the present invention were both increased by heat treatment. Examples and Comparative Examples A chemical copper plating bath having the following composition was manufactured, and Examples and Comparative Examples were prepared.
Plating was carried out in the same manner as in the comparative example.

[Table] Figure 5 shows the deposition rate when plating was carried out in the above bath with varying amounts of α,α'-dipyridyl. In the figure, A indicates the precipitation rate of the example bath, and B indicates the precipitation rate of the ethylenediamine-free bath among the comparative baths. From the results shown in Figure 5, in Comparative Example Bath B, which uses EDTA/4Na as a complexing agent but does not add ethylenediamine, when the amount of α,α'-dipyridyl exceeds 0.25 mmol/(0.00025 mol/), The precipitation rate was significantly reduced and the plating was uneven, but in Example Bath A, which used ethylenediamine in combination with the EDTA/4Na complexing agent, the precipitation rate remained constant even when the amount of α,α'-dipyridyl was increased. The degree of decrease in
It was found that the amount of α,α'-dipyridyl had an allowable range of about 10 times that of Comparative Example Bath B. In addition, without using EDTA/4Na as a complexing agent,
A comparative example bath in which ethylenediamine was used instead did not cause plating to precipitate at a plating temperature of 60°C. In this case, precipitation was possible by raising the plating temperature to 90°C, but the odor of ethylenediamine was so pronounced that it was impractical.

[Brief explanation of the drawing]

Figure 1 shows the fritted film obtained from the bath of the present invention.
A graph showing the changes in elongation and tensile strength after heat treatment at 160℃ for a predetermined time. Figure 2 shows the changes in elongation and tensile strength after heat treatment at 160℃ for a predetermined time on a damped film obtained from a comparison bath. The graph shown in FIG.
Figure 4 is a graph showing the elongation and tensile strength after heat treatment for 3 hours. Figure 4 is a graph showing the elongation and tensile strength after heat treatment of the tamped films obtained from the comparative baths at various temperatures for 3 hours. Figure 5 is a graph showing the elongation and tensile strength after heat treatment for 3 hours at various temperatures. 2 is a graph showing the relationship between the amount of α,α'-dipyridyl added and the precipitation rate in a bath with and without ethylenediamine.

Claims (1)

[Claims] 1 Contains copper ions, ethylenediaminetetraacetic acid or its salt in an amount equal to or more than the equimolar amount of copper ions, a formaldehyde reducing agent, ethylenediamine, and α,α′-dipyridyl as a complexing agent for copper ions. A chemical copper plating bath that is characterized by