JPH0319307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for electroplating nickel, cobalt, iron, or alloys thereof using an insoluble anode, and more specifically, for plating electronic components, etc. In particular, the present invention relates to an electroplating method that is suitably adopted for high-speed plating and partial plating.

Conventional techniques and problems to be solved by the invention Conventionally, in electroplating of nickel, cobalt, iron, or their alloys, soluble anodes have been mainly used as anodes, and insoluble anodes have rarely been used. Someone was there. For this reason, these electroplating solutions such as Nickel are considered to be suitable for use with soluble anodes, and little thought has been given to the composition of electroplating solutions such as Nickel that are suitable for use with insoluble anodes. It was hot.

However, in recent years, there has been an increasing demand for high-speed partial electroplating of nickel, etc. for functional plating of electronic components, etc., but in this case, insoluble anodes are used due to limitations in plating equipment. Therefore, there is a need to develop electroplating solution compositions such as nickel suitable for use with insoluble anodes.

The present invention has been made in view of the above circumstances, and is directed to the electroplating of nickel, cobalt, iron, or alloys thereof, which can provide a hardened film with excellent physical properties even when used continuously for a long period of time when an insoluble anode is used. The purpose is to provide a method.

Means and Effects for Solving the Problems In order to achieve the above object, the present invention contains a sulfate of one or more metals selected from nickel, cobalt, and iron as a source of metal ions, and o- The object to be plated is immersed in an electroplating solution containing additives and surfactants selected from sulfobenzoic acid imide salts, coumarin, acetylene alcohol, and their derivatives, and which does not contain halogen ions. The object of the present invention is to provide an electroplating method characterized in that the object to be plated is electroplated by passing electricity between the object and the anode.

That is, as a result of various studies on electroplating liquids such as nickel suitable for insoluble anodes, the present inventors have determined that sulfates of one or more metals selected from the above-mentioned nickel, cobalt, and iron can be used as metal ions. An electroplating solution containing as a supply source, an additive selected from salts of o-sulfobenzoic acid imide, coumarin, acetylene alcohol, and derivatives thereof, and a surfactant, and containing no halogen ions is insoluble. It was found that this method is effective for electroplating using an anode.

To explain this point in more detail, nickel plating solutions for decorative plating that use ordinary soluble anodes, such as Watt-type nickel plating solutions, contain chlorides, which are directly used in applications that use insoluble anodes. When used for plating, chlorine gas is generated at the anode during the electrolysis process, which not only makes the working environment worse, but also causes problems such as erosion of insoluble anodes such as platinum. In addition, when plating with a nickel sulfamic acid plating solution using an insoluble anode, the sulfamic acid undergoes anodic oxidation and decomposes, or undergoes hydrolysis to produce ammonium salts, so as electrolysis progresses, There are problems such as increased stress and hardness, decreased flexibility, and finally cracks in fitting, and there are many problems in using the insoluble anode continuously over a long period of time.

In addition, additives such as brighteners and surfactants are often added to ordinary plating solutions for nickel and other materials in order to impart gloss and improve the physical properties of the plating film. If this is directly plated using an insoluble anode, the additive will be decomposed in the insoluble anode, resulting in increased consumption of the additive, reduction in gloss and physical properties of the film, and increase in bits and pinholes. According to studies by the present inventors, many of the known brighteners for nickel plating are not suitable for insoluble anodes. However, if a brightener or a surfactant is not added, the plated film may have an uneven appearance, considerable stress is generated, causing problems in terms of physical properties, and even bits are generated.

As a result of such studies, the present inventor has developed an electric lamp using an insoluble anode that does not generate chlorine gas, etc., and does not deteriorate the properties of the plating film or cause pits or pinholes even after long-term electrolysis. When a sulfate of a metal such as nickel is used as a source of metal ions, no gas harmful to the human body is generated and the insoluble anode is not eroded, so it can be used stably over a long period of time. It is possible to obtain a flexible plating film with low stress, and when using o-sulfobenzoic acid imide salt, coumarin, acetylene alcohol, or their derivatives as additives, it is possible to obtain a plating film with long-term electrolysis. It has been found that it is difficult for decomposition products that have an adverse effect on the surface to accumulate, and that it is possible to provide a film with good physical properties, and furthermore, when these additives and a surfactant are used in combination, pits and pinholes are less likely to occur. In particular, as an additive
- When using a metal salt of sulfobenzoic acid imide,
This is because it is difficult to accumulate decomposed products that adversely affect plating even when decomposed by oxidation, and these decomposed products can be easily removed by treatment with activated carbon. Even if the plating bath is used electrolytically for a long time, the plating internal stress will be -10 to 10.
It has low stress of less than Kg/mm ² , does not increase hardness or become inflexible, has good physical properties with almost constant hardness and flexibility, and has a whitish semi-finish color. The present invention was based on the discovery that a plating film having a glossy appearance and a uniform appearance can be obtained over high and low current density areas or regardless of the size of the diffusion layer.

The present invention will be explained in more detail below.

In the electroplating method using an insoluble anode of the present invention, the electroplating solution contains a sulfate of one or more metals selected from nickel, cobalt, and iron as a source of metal ions, and o-sulfobenzoic acid A material containing a surfactant and an additive selected from imide salts, coumarin, acetylene alcohol, and derivatives thereof, and containing no halogen ions is used.

Here, the sulfates include nickel sulfate, cobalt sulfate, ferrous sulfate, and hydrated compounds thereof, and these sulfates are preferably used at a concentration of 400 to 600 g/, particularly 450 to 550 g/. . Note that there is no particular restriction on the alloy composition when obtaining an alloy coating, and sulfates of nickel, cobalt, and iron may be used in any ratio.

In addition, as additives, salts of o-sulfobenzoic acid imide, coumarin, acetylene alcohol, and one or more types of these derivatives are used.
-Metal salts of sulfobenzoic acid imide such as sodium, potassium, nickel, and cobalt are mentioned, and the amount used is 0.1 to 3 g/, especially 0.1 to 1
g/, and especially when gold plating or silver plating is applied to the plating film, o
- From the viewpoint of adhesion, it is desirable that the amount of the metal salt of sulfobenzoic acid imide added be small. Furthermore, when coumarin or its derivatives are used, the amount used is preferably 0.01 to 0.5 g/, particularly 0.05 to 0.2 g/, and the amount of acetylene alcohol such as butynediol or its derivatives used is 0.01 to 0.5 g/.
g/, particularly preferably 0.02 to 0.2 g/.

Among these, salts of o-sulfobenzoic acid imide are particularly preferred. In other words, compared to other additives, o-sulfobenzoic acid imide salts are less likely to accumulate decomposition products that have a negative effect on plating when decomposed by oxidation, and the oxidation decomposition products are almost completely eliminated by treatment with about 10 g of dry activated carbon. It can be removed and the condition will return to the same as the new solution. Therefore, a plated film with good physical properties can be provided. That is, when a salt of o-sulfobenzoic acid imide is used, it is possible to obtain a plated film with low stress, constant flexibility and hardness, and uniform appearance even after long-term electrolysis.

In addition, when a semi-gloss uniform appearance is required, coumarin, acetylene alcohol, or a derivative thereof can be used together with or in place of the o-sulfobenzoic acid imide salt. can.

In addition, the plating film is used as a post-treatment for 300 to 600
In the case of heat treatment at about ℃, it is preferable to obtain a sulfur-free plating film.
It is desirable to perform plating without adding sulfobenzoic acid imide. In this case, if the appearance or physical properties of the film are not a problem, plating can be carried out by adding only a surfactant without adding any additives.

A surfactant is further added to the plating solution of the present invention, and the surfactant is preferably an anionic surfactant such as sodium lauryl sulfate or sulfosuccinate, and the concentration thereof is 0.001 to 0.2 g/
It is particularly preferable to set the amount to 0.01 to 0.05 g/.

It is preferable to further add a buffer to the plating solution of the present invention. As the buffering agent, boric acid is preferable, and the amount used is 25 to 50 g/, especially 30 to 40 g/
It is preferable that

Furthermore, the pH of the electroplating solution according to the present invention is 2 to 2.
5, particularly preferably 2.5 to 4.8. In this case, sulfuric acid can be used to lower the pH, and nickel carbonate can be used to raise it.

The electroplating method of the present invention uses the electroplating solution described above, immerses the object to be plated in the electroplating solution, and conducts plating by passing electricity between the insoluble anodes.

In this case, there are no particular restrictions on the insoluble anode, and the material may be lead alloy, carbon, stainless steel, titanium, platinum, etc., and the shape may be a rod, plate, net, etc.
A wire, spherical, or oval shape may be selected and used, but it is especially preferable that the material of the insoluble anode is platinum or platinum-plated titanium.

When plating using the plating solution of the present invention, the plating conditions can be the same as those for known Ni, Co, Fe, or their alloy plating, and the upper limit of the plating solution temperature is the plating temperature. Although it varies depending on the material of the tank and plating equipment, the temperature is 10 to 80℃, preferably 40 to 65℃.
℃, cathode current density, the maximum current density that can be applied varies depending on the plating solution temperature, solution flow rate, moving speed of the object to be plated, metal ion concentration in the plating solution, etc.
Usually conditions of 7 to 50 A/dm ² may be adopted. The plating solution may be circulated using air agitation, cathode locking, pumps, etc. as necessary.
Propeller stirring, other methods using moving or vibrating the plated items can be used.

There are no particular restrictions on the material of the product to be plated using the electroplating method of the present invention, and any material that can be electroplated can be plated, such as metals, conductive plastics, ceramics, etc. I get scolded. In this case, these can be plated using the electroplating method of the present invention after being subjected to a known pretreatment and a desired base plating,
Further, after plating by the electroplating method of the present invention, chrome plating, gold plating, silver plating, or other desired plating can be applied thereon, or known post-treatment can be performed thereon.

The electroplating method of the present invention is particularly suitable for high-speed, partial plating of printed circuit board terminals, and can be effectively used as a base for gold plating.
It is used for hoop plating for silver and plating bases, for plating lead frames, and for plating IC and LSI package leads and pattern parts.

Effects of the Invention According to the electroplating method according to the present invention, a plated film with excellent physical properties can be stably obtained over a long period of time using an insoluble anode, and therefore high-speed partial plating on electronic components, etc. It is suitable for use in applications such as

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples.

Example 1, Comparative Example High-speed partial plating was carried out on the following objects to be plated using the following plating solution, plating apparatus, and plating conditions.

Plating liquid NiSO ₄ 6H ₂ O 550g / H ₃ BO ₃ 35g / o-sulfobenzoic acid imide sodium salt
2g / Sodium lauryl sulfate 0.01g / PH 2.5 Plating device A jet of plating solution is applied to the object to be plated, and the plating solution is sent from the storage tank to the jet-type plating cell using a pump and circulated.

Plating object (cathode) Printed circuit board terminal: 25 terminals of 2 mm width and 23 mm length on one side (50 terminals on both sides) Effective plating area: 0.2 dm ² (both sides) Anode 10 x 70 x 1 mm platinum plated A titanium plate (2μm) is placed on both sides at a distance of 15mm from the terminal plating surface.

Plating conditions D _K : 25A/dm ² D _A : Approx. 3.6A/dm ² liquid Temperature: 55℃ Liquid flow rate: 770/hr Plating time: 1 minute Plating film thickness: Approx. 4μm After forming the nickel plating film, known acidic gold plating was electrodeposited on the nickel plating film to a thickness of about 2 μm to obtain a terminal Ni-Au plating film.

For comparison, in Example 1, 1,3,6
- Sodium naphthalene trisulfonate 2g/
A terminal Ni-Au plating film of a comparative example was obtained in the same manner as in Example 1, except that .

The nickel plating film of the comparative example had a severe increase in tensile stress as the electrolysis progressed, an uneven appearance, many pits, an increase in hardness, and a decrease in flexibility. However, the nickel plating film of Example 1 satisfied all required performances such as hardness, stress, flexibility, appearance, corrosion resistance, shearing test, and porosity, and was suitable for nickel metal parts. Although the deposition was carried out at high speed using an insoluble anode, it was found that it could be used satisfactorily for electronic parts.

Example 2 In order to repeatedly perform the nickel plating of Example 1 over a long period of time, the sodium salt of o-sulfobenzoic acid imide and nickel ions, which decrease with electrolysis in the plating solution of Example 1, are replenished. Ta. In this case, sodium salt of o-sulfobenzoic acid imide and nickel sulfate were added as appropriate depending on the amount of electrolysis, and at the same time nickel carbonate was added to adjust the pH of the plating solution. Also, use the above plating liquid.
After each 20AH/electrolysis, treatment is performed with 10g/dry activated carbon to remove decomposition products, and freshly added 20g/sodium salt of o-sulfobenzoic acid imide.
A nickel plating film was obtained in the same manner as in Example 1 by adding 100 g/g/g/ and carrying out long-term electrolysis up to 600 AH/g/g/.

Comparing the physical properties of the nickel plating film obtained from the new solution at the time of preparing the above plating solution and the physical properties of the nickel plating film after 600AH/electrolysis, they are almost the same, and are suitable for terminal plating. It was found to be very effective as a nickel plating.

Specifically, a plated film with the following characteristics was obtained by electrolysis at 0 to 600 AH/.

Hardness (microbits): Hv = 450 to 580 Stress: -10 to 10 Kg/mm ² Bending: As a result of a qualitative bending test of the coating, all coatings were found to be flexible.

Shearing test: Printed circuit board terminals with approximately 5 μm nickel plating were cut by shearing, and all results were passed.

Porosity: Similarly, a test similar to the feroxyl test was conducted on a nickel plated film of about 5 μm, and the result was that the porosity was less than 2 pores/cm ² , with an average of 0.5 pores/cm It was about ² .

Example 3 NiSO ₄ 6H ₂ O 550g / H ₃ BO ₃ 35g / Coumarin 0.5ml / Sodium lauryl sulfate 0.01g / PH 3.0 Using the above plating solution, solution temperature 60℃, Dk20A /
Nickel plating (3 μm) was applied to a copper hoop material with a width of 3.8 mm and a thickness of 0.5 mm under conditions of dm ² . in this case,
The anode is 10mm in diameter with 2μm platinum plating.
A titanium rod was used.

The obtained plating film had a uniform appearance and good physical properties, and as in Example 2, there was no decrease in the plating physical properties even after long-term electrolysis, and the plating properties were 0 to 600 AH/
In electrolysis, it has a uniform semi-gloss appearance,
Hv300~450, stress 30~50Kg/ ^mm2 , flexible against bending, and no problem with shearing. When the porosity was measured, it was less than 2 pores/ ^cm2 , with an average of 0.5 pores/cm2.
It was about ^cm2 .

Furthermore, when we cut the nickel-plated hoop described above and conducted a solderability test on the nickel-plated part, we found that the nickel-plated area remained intact despite the heat treatment during soldering. Good solderability was obtained with almost no deterioration in physical properties.

Claims (1)

[Claims] 1 Contains a sulfate of one or more metals selected from nickel, cobalt, and iron as a source of metal ions, and an additive selected from salts of o-sulfobenzoic acid imide, coumarin, acetylene alcohol, and derivatives thereof. The object to be plated is immersed in an electroplating solution containing a surfactant and a surfactant and does not contain halogen ions, and the object to be plated is electroplated by passing electricity between the electroplating solution and an insoluble anode. An electroplating method characterized by: