JPH0748681A - Plating method using both electroless plating and electroplating - Google Patents

Abstract

(57) [Abstract] [Purpose] Over the entire surface of the work material having a special shape such as a corrugated shape having a cylindrical shape or a bent portion, it has a gloss as good as a normal flat material, a beautiful appearance, and excellent corrosion resistance. It is an object of the present invention to provide a plating technique capable of forming a uniform metal film having good adhesion. [Structure] When plating various shapes such as cylindrical and corrugated shapes, after pretreatment to adjust the surface condition of the material to be processed, the surface of the material is processed by electroless plating.
A plating method using both electroless plating and electroplating, which comprises depositing metal ions on the entire back surface to form a metal film, followed by electroplating and further final finishing treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating method using both electroless plating and electrolytic plating.

[0002]

2. Description of the Related Art Electroplating has been carried out for a long time and is roughly classified into anticorrosion, decoration and industrial use depending on its use.
There are many platings used for both, platinum, gold,
There are platings of silver, copper, nickel, chromium, lead, tin, etc.

For example, nickel plating is nickel sulfate-
Matte plating using ammonium chloride-boric acid bath,
Brightness plating with nickel sulfate-nickel chloride-boric acid-brightener bath.

[0004] Recently, strike plating has been carried out by electroplating in various special solution baths to form a thin film on the surface of the material to be processed of various shapes, but with this method also, the inner surface of the pipe-shaped material and the corrugated material are For bent deep areas, there are areas where current does not flow well or areas where current does not flow at all, which results in poor adhesion of the plating, no metal ions are deposited, and no metal film is formed. In some cases, the substrate remains exposed. When such a part comes into contact with the treatment liquid in the next process, there are drawbacks such as the elution of the material, the deterioration of the plating liquid, and the corrosion of the base material. However, there were fatal defects such as a large number of defective products, resulting in a decrease in product yield.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art and, in contrast to a material having a special shape such as a cylindrical shape or a corrugated shape having a bent portion, a normal flat material. Similarly to the above, the present invention proposes a plating method capable of forming a uniform metal film having gloss, a beautiful appearance, excellent corrosion resistance, and good adhesion.

[0006]

[Means for Solving the Problems] As a result of various experiments and studies to eliminate the drawbacks of the prior art, the present applicant has performed electroless plating (chemical plating) before electroplating to obtain a special shaped material. The present invention was found to be able to completely eliminate the conventional defects by precipitating metal ions over the entire front and back surfaces to form a uniform metal film, and then performing ordinary electroplating and finishing treatment. It came to the point that

That is, according to the present invention, when a material to be processed in various shapes such as a plate shape, a cylinder shape, and a corrugated shape is plated, no electric energy is used after a pretreatment for adjusting the surface condition of the material to be processed. After performing electroless plating to uniformly deposit metal ions in the aqueous metal salt solution on the entire front and back surfaces of the material to be processed by a substitution reaction to form a metal film, then activate as necessary, and then After applying normal electroplating,
The present invention relates to a plating method that uses both electroless plating and electroplating, which is characterized by performing a final finishing treatment.

The material to be processed is preferably aluminum or its alloy, copper or its alloy, or iron or its alloy, and the electroless plating bath composition is composed of a metal salt, a reducing agent and a buffering agent. It is preferably composed of three kinds.

For example, in the case of electroless plating (chemical plating) of nickel, nickel sulfate, nickel chloride or the like is used as the metal salt, sodium hypophosphite or the like is used as the reducing agent, and sodium acetate is used as the buffering agent. ,Boric acid,
There are tartaric acid, sodium citrate, sodium succinate, etc., and may also contain various other brighteners.

The liquid composition of the plating bath can be appropriately determined by preliminary experiments depending on the material of the material to be processed. Usually, in the case of iron or its alloys, an acidic bath is used, and in the case of nonmetals such as plastics. Uses a basic bath.

Regarding the metal ion concentration, the electroless plating bath is different from the electroplating bath, and since the metal ions are supplied from these metal salts, adjusting the concentration of these metal salts is one of the bath management. It is an important factor.

Next, in addition to the metal salt, a reducing agent is an important element constituting the bath. The reducing agent is most important in the process of metal precipitation. For example, when the metal salt is a nickel salt and the reducing agent is hypophosphite, 2 [H ₂ PO ₂ ⁻ ] + 2H ₂ O + [Ni ²⁺ ] → 2 [H ₂ PO ₃ ⁻ ] + Ni ↓ + H ₂ ↑ .. (1), but in actual operation, the equivalence ratio of the two is not the same as in the above reaction formula (1), and is slightly different.

As the buffering agent, as described above, organic acids are mainly used, but stabilizers and brighteners are also included, and these chemicals naturally have the optimum ratios, and these adjustments are sufficiently performed during the plating operation. I need to do it.

Further, since it is related to the thickness and adhesion of the plating, it is necessary to sufficiently control the fluctuation of PH in the plating bath, the time, the temperature and the like.

As described above, in the case of electroless plating, it goes without saying that the replenishment of chemicals, the relationship between the processing surface area and the bath capacity, the life of the bath, etc. are important for management.

The method of the present invention is characterized in that electroless plating is performed before electroplating in place of conventional strike plating in the plating process, whereby a metal film is formed on the entire surface of the substrate, and electroplating is performed. Not only the plated surface, but also the overall appearance of the product can be improved, and at the same time, corrosion resistance can be improved.

That is, by performing electroless plating before electroplating, even deep parts of the inner surface and the bent portion of a material having a special shape such as a cylindrical shape or a corrugated shape, which cannot be formed by the strike plating, can be formed. , In other words, metal ions can be deposited on the entire surface where the plating solution comes into contact to form a metal film, so that the elution of the base material in the bath in the next step can be prevented, and further, the conductivity can be improved. Since the distribution of the electric current is made more uniform, the covering power and adhesion of the electroplated film can be improved.

After the above electroless plating treatment, an activation treatment is applied if necessary. Subsequent electroplating is performed by a known technique. Next, examples of the present invention will be described.

[0019]

【Example】

Example-1 FIG. 1 is a schematic flow sheet showing a nickel plating treatment process on an aluminum material according to the method of the present invention, and the method of the present invention will be described with reference to the drawing.

A corrugated plate-shaped aluminum material having a bent portion is first made into Alclean 101 (trade name) 50 g / l.
(Phosphate: 20 g / l, carbonate: 25 g / l, surfactant: 5 g / l) Immersed in a degreasing bath having a bath composition of 60 ° C. for 10 minutes for alkaline degreasing, followed by washing with water, then arsatin PRE (trade name) 300 ml / l (phosphoric acid: 300 g
/ L, additive: 40 g / l), nitric acid: 200 ml / l in an etching bath having a bath composition of 90 ° C. for 90 seconds for micro-etching treatment, followed by washing with water, and then Substar Zn
-111 (trade name) 500 g / l (sodium hydroxide:
140 g / l, zinc metal: 38 g / l) A zincate treatment bath having a bath composition of 140 g / l) was soaked at 22 ° C. for 30 seconds for zincate treatment (improving adhesion), followed by washing with water, and nitric acid 500 ml / l
After being immersed in the bath for 20 seconds for zincate peeling treatment and again subjected to the above zincate treatment (at 22 ° C. for 30 seconds), the following electroless plating treatment was performed.

The electroless plating bath composition is Top Nicolon B
LM (trade name) 100 ml / l and Top Nicolon BL
-I (trade name) 60 ml / l (nickel salt: 20 g /
l, hypophosphite: 20 g / l, additives (stabilizer, brightener, etc.): 20 g / l), the temperature of the bath is kept at 90 ° C., electroless plating is performed for 13 minutes, and the thickness is A 3μ nickel plating film was formed over the entire surface of the aluminum material. As a result, the obtained product was completely plated up to the bent deep part.

Next, since the nickel coating surface is likely to become non-conductive, 60% in a 10% sulfuric acid solution is used to improve the adhesion.
After activating for seconds, nickel sulfate 280 g / l, nickel chloride 45 g / l, boric acid 40 g / l, brightener A:
15 ml / l, brightener B: 0.75 ml / l, pH 4.
Hold the plating bath having the bath composition of No. 2 at 50 ° C., and perform electroplating for 25 minutes while stirring in air under the conditions of cathode current density of 3 A / dm ² and positive current density of 1.5 A / dm ² , and aluminum material After forming a nickel plating film having a thickness of about 13 μ on the surface, it was washed with water.

The product obtained has no pinholes or the like,
The nickel plating film was formed uniformly not only on the flat surface portion but also on the deep portion of the bent portion.

Next, chrome plating was applied as finish plating under the following conditions to obtain a final product. That is, the nickel electroplated aluminum material as described above is thoroughly washed with water, then activated for 20 seconds in a 10% chromium recovery bath, and then washed with water to give 250 g / l of chromic anhydride and 1.6 g of trivalent chromium. / 1, sulfuric acid 2.3g / l bath composition of chromium plating bath kept at 45 ℃, cathode current density (DK): 20A
And 2 minutes plating under conditions of / dm ^2, a thickness of 0.3μ
Formed a chromium film. After thoroughly washing with water until chromium ions are no longer detected, dry at 55 ° C for 6 minutes,
The final product.

As a result, the product obtained is glossy,
It had a chrome color and a beautiful appearance, and was excellent in adhesion and corrosion resistance.

Example 2 As in Example 1, the aluminum material having the glossy nickel plating film obtained by the pretreatment → electroless plating → electroplating process was treated with white as a finishing treatment. Alloy finish was applied under the following conditions.

First, after thoroughly washing with water, stannous pyrophosphate 20 g / l, cobalt chloride 20 g / l, potassium pyrophosphate 250 g / l, brightener 10 ml / l, a white alloy plating bath having a bath composition of pH 8.7 50. The temperature was maintained at 0 ° C., and the plating was performed for 2 minutes under the condition of the cathode current density (DK) of 0.7 A / dm ² to form a bright tin-cobalt alloy film having a thickness of 0.3 μm. After thoroughly washing this with water, chromate treatment for 30 seconds to improve corrosion resistance and gloss finish,
It was dried at 5 ° C. for 6 minutes.

The obtained final product has excellent corrosion resistance,
It had a color tone similar to that of chrome and had a unique and beautiful appearance in place of chrome plating.

Example 3 In the same manner as in Example 1, the aluminum material on which the bright nickel-plated film obtained by the treatments of pretreatment → electroless plating → electroplating was formed was subjected to a black alloy finish as a finishing treatment. It was applied under the following conditions.

After washing with water beforehand, stannous pyrophosphate 10 g / l, cobalt chloride 30 g / l, potassium pyrophosphate 320 g / l, brightener 20 ml / l, pH 8.7
The black alloy plating bath having the bath composition of
The black tin-cobalt alloy plating layer having a thickness of 0.3 μm was formed by performing treatment for 2 minutes under the condition of the cathode current density (DK) of 1.0 A / dm ² . This was thoroughly washed with water, chromated for 30 seconds to improve the corrosion resistance, and dried at 55 ° C. for 6 minutes.

As a result, the final product obtained was excellent in corrosion resistance and had a unique beautiful black appearance.

[0032]

As described above, according to the present invention, when a material to be processed having various shapes is plated, a pretreatment for adjusting the surface condition of the material is performed, and then the entire front and back surfaces of the material are electroless plated. Metal ions are deposited to form a metal film, which is then subjected to publicly known electroplating and then final finishing treatment. It is possible to deposit metal ions to the deep part of the corrugated plate, that is, the entire surface of the electroless plating that comes into contact with the plating solution, to form a metal film, so elution of the base material in the bath in the next step It is possible to completely prevent corrosion, discoloration, etc. inside, and to improve the current carrying property to make the current distribution more uniform, so that it is possible to improve the covering power and adhesion of the electroplating film. Corrosion resistance can be greatly improved Te.

Further, according to the method of the present invention, it is possible to form a uniform metal film having various shapes on the surface of the material to be processed, which has a gloss, a beautiful appearance, excellent corrosion resistance, and good adhesion. The effect is further improved by applying finish plating such as chrome plating, white plating or black plating. Needless to say, the method of the present invention can be applied to the case where various metals are plated on various materials to be processed.

[Brief description of drawings]

FIG. 1 is a schematic flow sheet showing a nickel plating treatment process on an aluminum material according to the method of the present invention.

Claims (2)

[Claims] 1. A metal salt that does not use electric energy after plating a material to be processed in various shapes such as a plate shape, a cylindrical shape, and a corrugated shape, after performing a pretreatment for adjusting the surface condition of the material to be processed. After performing electroless plating for uniformly depositing metal ions in the aqueous solution on the front and back surfaces of the material to be processed by a substitution reaction to form a metal film, an activation treatment is carried out if necessary, and then the usual A plating method that uses both electroless plating and electroplating, which comprises performing electroplating and then final finishing. 2. The material to be processed is aluminum or an aluminum alloy, copper or a copper alloy, iron or an iron alloy, and the electroless plating bath composition is a metal salt,
The plating method using both electroless plating and electroplating according to claim 1, comprising three kinds of a reducing agent and a stabilizer, and a buffer containing a brightening agent.