JPS5933666B2 - chemical copper plating liquid - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a chemical copper plating solution, and more specifically, to a new composition capable of high-speed deposition and forming a matted film with excellent mechanical properties, especially spreadability. Regarding chemical copper plating solution.

[Technical background of the invention]

Chemical copper plating solutions are known that have an autocatalytic action that allows copper to be deposited electrolessly and continuously.

Such chemical copper plating solutions usually contain copper sulfate, dichloride, etc.
Water-soluble copper salts such as copper; ethylenediaminetetraacetic acid (EDT
A) Cupric ion complexing agents such as N, N, N', N'-tetrakis(2-hydroxypropyl)monoethylenediamine, Rothsiel's salt; Reducing agents such as formaldehyde, dimethylaminoborane, sodium borohydride; Hydroxylation It is composed of a pH adjuster such as sodium and potassium hydroxide; and, if necessary, a surfactant such as polyethylene oxide, polyether, polyester, etc.
(See Publication No. 67, etc.) [Problems of the Background Art] However, the plating film obtained from the above-mentioned staining solution is generally brittle and has insufficient mechanical properties, particularly spreadability, for practical use.

For example, in the manufacture of printed wiring boards using the so-called additive method, in which the current-carrying circuit portion of the printed wiring board is formed by chemical copper plating, thermal stress and physical shock due to processing of the printed wiring board and environmental changes are important. As a result, circuit breakage is likely to occur. In order to improve the above drawbacks, polyethylene glycol, dipyridyls, phenanthrolines, or water-soluble cyanide were added to a chemical copper plating solution containing a copper salt, a cupric ion complexing agent, a reducing agent, and a pH adjuster. Attempts have been made to improve the spreadability of chemical copper plating films by further adding compounds and nitriles.

However, even if the above-mentioned components are added, the spreadability of the chemical copper plating film is only slightly improved, and the mechanical properties of the plating film are not suitable for practical use, for example, as a copper film forming the current-carrying circuit of a printed wiring board. It has not yet reached the point where it can be provided.

Moreover, when these components are added, an inconvenient situation arises in that the plating precipitation rate decreases. Therefore, if this problem is improved and the deposition rate is increased, disadvantages such as deterioration of the mechanical strength of the plating film and deterioration of the stability of the plating solution cannot be avoided. Therefore, it has been desired to develop a chemical copper plating solution that does not have the above-mentioned drawbacks.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks, enables high-speed precipitation,
The object of the present invention is to provide a chemical copper plating solution that has excellent mechanical properties, particularly spreadability, provides a copper plating film with a beautiful appearance such as gloss, and is stable.

[Summary of the Invention] The chemical copper plating solution of the present invention is characterized in that it contains a cuprous ion complexing agent containing a nitrogen ring.

That is, the chemical copper plating solution of the present invention is a chemical copper plating solution containing a water-soluble copper salt, a cupric ion complexing agent, a reducing agent, and a PH adjuster, and has the following formulas (4) to (0: (In the formula, R1 and R2 are each a hydrogen atom, a phenyl group,
Represents a substituted phenyl group; R3 to R6 each represent a hydrogen atom or a lower alkyl group; R7 and R8 each represent a hydrogen atom or an aromatic ring to which R7 and R8 are bonded, or a substituted aromatic ring; R9 and RlO each represents a lower alkyl group.

) It is characterized by containing at least one kind of cuprous ion complexing agent selected from the compounds shown in the following.

As for the functions of each component of the chemical copper plating solution in the present invention, the water-soluble copper salt serves as a supply source of copper ions, and the reducing agent for copper ions supplies electrons that reduce the copper ions to a metal state.

The cupric ion complexing agent forms a stable complex with divalent copper ions and prevents the formation of cupric hydroxide during alkaline dissolution. ...modifiers adjust the optimal deposition potential of the bath. Here, the cuprous ion complexing agent prevents the self-decomposition of the plating solution, that is, the self-precipitation due to the formation of cuprous oxide, thereby extending the life of the plating solution and improving the mechanical properties of the plating film. It is intended to improve All of these components are indispensable and important, but the cuprous ion complexing agent according to the present invention is particularly important for solving the conventional problems.

The present invention will be described in further detail below.

The water-soluble copper salt used in the chemical copper plating solution of the present invention is usually copper sulfate. The choice is primarily based on economic considerations; in addition, copper chloride, copper nitrate, copper acetate and organic and inorganic copper salts can also be used. However, since these copper salts dissolve in water to form acoions, hydroxides precipitate in alkaline regions. Therefore, a complexing agent (
Chelating agent D is required. Examples of complexing agents for divalent copper ions include Rothsiel's salt, sodium salt of ethylenediaminetetraacetic acid, nitriloacetic acid and its alkali salts, gluconic acid, triethanolamine, diethylenetriaminepentaacetic acid, etc., but from a cost standpoint Ethylenediaminetetraacetic acid salts are the most useful.

Copper ion reducing agents used in alkaline chemical copper plating solutions include formaldehyde and its condensates and derivatives, such as paraformaldehyde, glyoxal, trioxane and the like.

Other reducing agents include borohydrides such as alkali metal borohydrides, such as sodium and potassium borohydrides, or substituted borohydrides, such as sodium trimethoxyborohydride. Additionally, amine borane, sodium or potassium hypophosphites and the like can be used. P.H.
The regulator may be an acid or a base, and its selection is based on cost considerations. Usually, sodium hydroxide is used as a chemical to raise the pH, and sulfuric acid is used as a chemical to lower it. The cuprous ion complexing agent that plays the most important role in the present invention has the formula ^~(C
), specific examples of which are the following compounds:

Compounds included in formula (to) 3-(2-pyridyl)-1,2,4-triazine, 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine, 3-(2- pyridyl)
- 5,6-diphenyl-1,2,4-triazine-
P,Yy'-disulfonic acid (2Na salt), 3-(2
-pyridyl)-6-phenyl-1,2,4-triazine, 3-(2-pyridyl)-6-phenyl-1,
Sodium 2,4-triazine-P-sulfonate formula (B
) The compound 2,2'-bis(5,6-dimethyl-1,2,4-triazine)2,2'-bis(5,6
-diethyl-1,2,4-triazine)2,2'-bis(5,6-dibutyl-1,2,4-triazine)2,2
'-bis(5,6-dipropyl-1,2,4-triazine) Compound contained in formula (C) 6,7-dimethyl-2,3-di(2-pyridyl)-quinoxaline 2,3-bis( 6-methyl-2-pyridyl)
-5,6-dihydropyrazine2,3-bis[2-(
6-methylpyridyl)]-quinoxaline 2,3-bis(2-pyridyl)-quinoxaline 6,7-diethyl-
2,3-di(2-pyridyl)-quinoxaline 2,3-di(2-pyridyl)-5,6-dihydropyrazine' These are considered to be effective from the following reaction.

That is, the chemical copper plating reaction when formaldehyde is used as a reducing agent is represented by (wherein, L represents a cupric ion complexing agent).

Among these, force 1) is the main reaction in chemical plating, in which formaldehyde reduces and precipitates copper ions on a copper catalyst. Formula (2) is a CannizarO reaction, which occurs slightly. Equations (3) and (4) are natural decomposition reactions. The CU2O produced in formula (3) promotes the reaction in formula (1) by using metallic copper (Cu) in the liquid produced in formula (4) as a catalytic nucleus, and promotes the decomposition of the liquid. Furthermore, CU2O is mixed into the plating film and reduces its mechanical strength. That is, a brittle film with low tensile strength and no elongation is formed. Therefore, from the purpose of the present invention, it is important to suppress the reactions of forces 3) and (4). Here, the cuprous ion complexing agent according to the present invention has the effect of forming a stable complex with Cu and dissolving the formed CU2O.

Furthermore, the surfactant has the function of adsorbing CU2O, fending off the attack reaction caused by the reducing agent, and preventing self-decomposition. The former alone is effective, but when both are used together, the plating solution is further stabilized and the mechanical properties of the film, ie, tensile strength and elongation, are significantly improved. The cuprous ion complexing agent that exhibits such effects selectively reacts with Cu to form a stable complex having a tetrahedral structure.

This complexing agent is effective in a small amount in a chemical copper plating solution, and the amount added is preferably in the range of 1Tf19/l to 200·W9/l. If the amount added is less than 1~/l, the spreadability of the plating film will not be improved, and if it exceeds 200~/11,
The plating deposition rate and working efficiency are reduced, and the effect of improving the spreadability of the film is not improved much. In the present invention, as described above, it is preferable to add a surfactant.

The surfactant may be either nonionic or ionic as long as it is a compound applicable to ordinary chemical copper plating solutions, but nonionic surfactants are preferred. Specific examples include polyethylene oxide, polyether,
Examples include polyester. More preferably, polyethylene glycol having a molecular weight of 200 to 20,000,
or the following formula: (where m and n are integers of 1 or more,
+n>12).

These have the effect of increasing the function of the cuprous ion complexing agent. The amount added is usually 101!9/l to 10
It is in the range of 9/l. Generally, the lower the molecular weight of the compound, the higher the concentration needs to be. If the amount added is less than 10 g/l, the spreadability of the plated film will not be improved, and if the amount added is less than 10 g/l,
If it exceeds l, the precipitation rate will become slow. Further, in the present invention, it is more preferable to use compounds represented by the above formulas as the cupric ion complexing agent.

Specific examples include the following compounds. Compounds included in the formula
N'-tetraethanol 2-hydroxypropyl-ethylenediaminedi(2-hydroxypropyl triacetate)monoethylenediaminediacetic acid formula (Compound contained in D -diethylenetriaminediethylenetriamine-N,N,N',N",N"-pentaethanol 2-
Hydroxypropyl-diethylenetriaminetetraacetic acid hydroxyethyl-diethylenetriaminetetraacetic acid di(2-hydroxypropyl)-diethylenetriaminetriacetic acid di(
Hydroxyethyl)-diethylenetriaminetriacetic acid These cupric ion complexing agents form stable complexes with cupric ions and have the effect of preventing the formation of cupric hydroxide in alkaline solutions.

The amount added is preferably equal to or more than the same molar amount of cupric ion, ie, water-soluble copper salt. The reason for this is that cupric hydroxide is likely to be produced when the amount added is less than the same mole. The preferred operating temperature of the chemical copper plating solution of the present invention is 50 to 8
The temperature is preferably 0°C, more preferably 60 to 75°C.

Further, the pH used is preferably in the range of 10.8 to 13.0, more preferably in the range of 11.8 to 12.5. According to such plating conditions, the characteristics of the chemical copper plating of the present invention can be fully utilized, and as a result, high-speed deposition is possible.
It becomes possible to obtain a tamped film with excellent spreadability. [
Examples of the Invention Examples 1 to 6 An adhesive-coated laminate was used as a substrate on which a plating film was formed.

The adhesive layer has a thickness of about 40 μm and is a layer made of a mixture of nitrile rubber, phenol resin, and epoxy resin. The laminate is made of paper epoxy resin. The surface of this adhesive-coated laminate was modified as follows to make it suitable for forming a plating film. First, 50 boards C0Cr03809/1
, H2S04 for 2 minutes to roughen the surface.

Next, this was washed with water, immersed in a solution of NaHSO339/l for 3 minutes at room temperature for reduction treatment, and washed again with water.

Next, the substrate was coated with SnCl25Ofl/1, HC'10m
After sensitizing the sample by immersing it in a 1/l mixed solution at room temperature for 2 minutes, it was washed with water. After that, PdCll2O. 259/
1. It was immersed in a mixed solution of 110 ml/l of HC at room temperature for 2 minutes, and then washed under running water for 1 minute. Next, the substrate subjected to the above pretreatment was subjected to chemical copper plating.

The composition of the chemical copper plating solution is shown in Table 1. The plating conditions were PHI2.3 (prepared with NaOH) and a temperature of 70°C.
Further, as a comparative example, plating was performed using the conventional electroless copper plating solution shown in Table 1 under the same conditions as above.

Next, the obtained tough film (thickness: 30 to 35 μm) was peeled off from the substrate and subjected to a tensile test.

The measurement was performed using a tensile tester (manufactured by Shimadzu Corporation, Autograph Model PSS-5000) at 12.7×
150m7! The test piece cut into L is
0011, tensile speed 51! The test was carried out under conditions of 1/min. The results are also listed in Table 1. Examples 7 to 13, Comparative Examples 3 to 4 A stainless steel plate with a thickness of 0.3jEI was used as a substrate on which a plating film was formed.

This steel plate was treated as follows to modify the surface to be suitable for plating. First, a steel plate was polished with a cleanser and immersed in 10% sodium hydroxide solution at 80°C for 5 minutes.

Next, this was washed with water, immersed in 10% hydrochloric acid at room temperature for 5 minutes, and washed again with water to clean the surface. The steel plate was then immersed for 2 minutes in a solution consisting of the following composition:
Washed under running water for 1 minute.

Next, it was immersed in a solution having the following composition for 1 minute, and then washed in running water for 1 minute.

Next, the substrate subjected to the above pretreatment was subjected to chemical copper plating treatment.

The chemical copper plating composition consisted of the following, and the types and amounts of the cuprous ion complexing agent and cupric ion complexing agent used at this time are shown in Table 2. The plating conditions were PHL 2.3 and temperature 70°C. Further, as a comparative example, plating was performed using the conventional chemical copper plating solution shown in Table 2 under the same conditions as above.

The thus obtained copper plating film with a thickness of 30 to 35 μm was peeled off from the stainless steel plate, and a ductility test (180 μm) was performed.
℃ bending test).

First, the plating film was bent 1800 degrees in one direction to create a crease, then returned to its original position and pressure was applied to flatten the crease. This operation is counted as one bending operation. The above operation was repeated until the plating film broke at the crease, and the number of times the plating film broke was measured. On the other hand, similarly to Examples 1 to 6,
The above plated film was subjected to one tensile test.

The above results are summarized in Table 2.

In addition, in the table, PEG-1000 indicates polyethylene glycol having an average molecular weight of 1000.

Claims (1)

[Claims] 1. Water-soluble copper salt, cupric ion complexing agent, reducing agent, and pH
In a chemical copper plating solution containing a conditioning agent, the following formula (A)
~ (C): ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (A) ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼ (B) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (C) (In the formula, R^1 and R^2 represent a hydrogen atom, a phenyl group, a substituted phenyl group, respectively. :R^3 to R^8 each represent a hydrogen atom or a lower alkyl group; R^7 and R^8 each represent a hydrogen atom or R^7
and R^8 represent an aromatic ring or substituted aromatic ring;
R^9 and R^1^0 each represent a lower alkyl group. ) A chemical copper plating solution characterized by containing at least one cuprous ion complexing agent selected from the compounds represented by the following. 2 The cupric ion complexing agent has the following formulas (D) to (E):
▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (D) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (E) (In the formula, R^1^1 ~ R^
1^9 each represents a carboxyalkyl group or a hydroxyalkyl group, at least one of which represents a hydroxyalkyl group. 2. The chemical copper plating solution according to claim 1, comprising at least one compound represented by: