KR101499852B1 - Method for surface treatment of aluminum or aluminum alloy - Google Patents

Abstract

A step of forming a first electroless nickel plating film by removing an aluminum oxide film formed on a surface layer of aluminum or an aluminum alloy and a step of forming a second electroless nickel plating film on the surface of the first electroless nickel plating film An electroless nickel plating film is formed on the aluminum or aluminum alloy.

When an electroless nickel plating film is formed on aluminum or an aluminum alloy so as to prevent the generation of cracks in the plating film and the warpage of the silicon wafer is suppressed as much as possible to prevent aluminum or aluminum alloy The surface can be treated.

Aluminum, an oxide coating, electroless plating, nickel plating, silicon wafer,

Description

METHOD FOR SURFACE TREATMENT OF ALUMINUM OR ALUMINUM ALLOY

The present invention relates to a surface treatment method of aluminum or an aluminum alloy, particularly to a method of surface treatment of aluminum or an aluminum alloy when UBM (under bump metal) or bump is formed on a wafer by plating.

Conventionally, as a method of forming a UBM or a bump on a silicon wafer, there has been known a method of forming a zinc film by performing a zinc substitution treatment on an aluminum thin film electrode patterned on a wafer and then forming bumps by electroless nickel plating, A bump is formed by electroless nickel plating after the palladium treatment is performed in place of the zinc substitution treatment or a bump is formed by electroless nickel plating by autocatalytic electroless nickel plating after the surface of the aluminum thin film electrode is directly substituted with nickel Method and the like are used.

However, in the electroless nickel plating film formed by such a method, cracks are generated in the plating film due to the internal stress of the electroless nickel plating film, or the silicon wafer on which the electroless nickel plating film is formed is warped .

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and has an object of providing an electroless nickel plating film on an aluminum or aluminum alloy, Which can suppress the warping of the aluminum or aluminum alloy as much as possible.

The inventors of the present invention have made intensive investigations in order to achieve the above object and have found that when an electroless nickel plating film is formed on aluminum or an aluminum alloy to treat the surface of aluminum or an aluminum alloy, By sequentially forming electroless nickel plating films in a multilayer by electroless nickel plating baths of different types, cracks are not generated in the plating film, and the warpage of the silicon wafer is reduced to treat the surface of aluminum or aluminum alloy And the present invention has been accomplished.

Accordingly, the present invention provides a method for surface treatment of aluminum or an aluminum alloy described below.

(One):

A surface treatment method of an aluminum or aluminum alloy for forming an electroless nickel plating film on an aluminum or aluminum alloy of an object to be processed having at least aluminum or an aluminum alloy on its surface,

Removing the aluminum oxide film formed on the surface of the aluminum or aluminum alloy of the object to be treated and then removing the water soluble nickel salt, the hypophosphoric acid and / or its salt and the organic carboxylic acid other than the aminocarboxylic acid A first nickel plating step of forming a first electroless nickel plating film by using a first electroless nickel plating bath comprising a complex oxide and / or a salt thereof, and

Wherein the surface of the first electroless nickel plating film contains a water-soluble nickel salt, a hypophosphoric acid and / or a salt thereof, an aminocarboxylic acid and / or a salt thereof, and an organic carboxylic acid other than an aminocarboxylic acid And a second nickel plating step of forming a second electroless nickel plating film by using a second electroless nickel plating bath not containing the salt, characterized in that the surface treatment of aluminum or an aluminum alloy Way.

(2):

Wherein the first nickel plating process immerses the object to be treated in a removing solution for an aluminum oxide film containing a metal substitutable for aluminum to remove the aluminum oxide film and remove a substitution metal layer of aluminum and substitutable metal contained in the removing solution Forming process,

A step of removing the substituted metal layer with an acidic liquid having an oxidation action, and

And a step of forming a first electroless nickel plating film on the aluminum or aluminum alloy from which the replacement metal layer is removed and exposed.

(3):

The surface treatment method according to (2), wherein the aluminum oxide film removing liquid comprises a salt of a metal capable of substituting aluminum and an acid.

(4):

The surface (2) according to (2), wherein the aluminum oxide film removing liquid contains a salt or an oxide of a metal capable of substitution with aluminum, a solubilizing agent for the metal ion, and an alkali and has a pH of 10 to 13.5 Processing method.

(5):

The surface treatment method according to (3) or (4), wherein the aluminum oxide film removing liquid further contains a surfactant.

According to the present invention, when an electroless nickel plating film is formed on aluminum or an aluminum alloy to treat the surface of aluminum or an aluminum alloy, cracks are not generated in the plating film, and the warpage of the silicon wafer is suppressed as much as possible, Or the surface of the aluminum alloy can be treated.

DETAILED DESCRIPTION OF THE INVENTION [

Hereinafter, the present invention will be described in more detail.

A surface treatment method of the present invention is a surface treatment method of aluminum or an aluminum alloy which forms an electroless nickel plating film on an aluminum or aluminum alloy of an object to be treated having at least aluminum or an aluminum alloy on its surface, Or an aluminum oxide film formed on a surface layer of an aluminum alloy is removed and a water-soluble nickel salt, a hypophosphoric acid and / or a salt thereof and an organic carboxylic acid other than an aminocarboxylic acid and / or a salt thereof A first nickel plating step of forming a first electroless nickel plating film by using a first electroless nickel-phosphorus plating bath comprising

Wherein the surface of the first electroless nickel plating film contains a water-soluble nickel salt, a hypophosphoric acid and / or a salt thereof, an aminocarboxylic acid and / or a salt thereof, and an organic carboxylic acid other than an aminocarboxylic acid And a second nickel plating step of forming a second electroless nickel plating film by using a second electroless nickel plating bath not containing the salt. Hereinafter, each step will be described.

[First Nickel Plating Process]

In the present invention, a first electroless nickel plating film is first formed on aluminum or an aluminum alloy by removing an aluminum oxide film formed on a surface layer of aluminum or aluminum alloy to be processed. In removing the aluminum oxide film, A known method can be applied, and the aluminum oxide film is removed to form a first electroless nickel plating film on the exposed aluminum or aluminum alloy.

In this case, the object to be treated is immersed in a removing solution for an aluminum oxide film containing a metal capable of substituting aluminum, a replacement metal layer of a substitutable metal, which is contained in the removing solution, is formed while removing the aluminum oxide film, The first electroless nickel plating film may be formed on the exposed aluminum or aluminum alloy by removing the substitution metal layer with an acidic liquid having an oxidizing action.

As the removing solution for aluminum oxide film, a solution containing a salt of a metal capable of substitution with aluminum, an acid, preferably a surfactant (acidic removing solution), or a salt or oxide of a metal substitutable with aluminum, Of a solubilizing agent, an alkali, preferably a surfactant, and having a pH of 10 to 13.5 (an alkaline removing solution) can be suitably used.

(Acidic solution)

The metal constituting the metal salt contained in the acidic removing liquid is not particularly limited as long as it is a metal which can be substituted with aluminum. However, it is preferably a metal having a lower ionization tendency than aluminum. Examples thereof include zinc, iron, cobalt, nickel, , Mercury, silver, platinum, gold, and palladium. Examples of the metal salt include water-soluble salts such as nitrates and sulfates of these metals. Particularly, the sulfate is preferable because of the stability of the remover and the less aggressiveness against the aluminum or aluminum alloy material. These may be used singly or in combination of two or more. Among them, silver, nickel and copper are less likely to be deposited on other regions, and copper and silver have a significantly lower ionization tendency than aluminum. Therefore, the substitution reaction is more likely to proceed and the etching process time can be shortened Suitable.

The concentration of the metal salt used in the acid-removing liquid is not particularly limited, but it is usually 1 ppm or more, preferably 10 ppm or more, and usually 10,000 ppm or less, preferably 5,000 ppm or less, as the metal amount. If the concentration of the metal salt is too small, it may be necessary to substitute the aluminum with the base aluminum or to replenish the metal salt. On the other hand, when the concentration is excessively large, when the aluminum or the aluminum alloy is an electrode patterned on the wafer, the member other than the aluminum or the aluminum alloy is infiltrated, or the aluminum or the aluminum alloy comes out of the member other than the aluminum or aluminum alloy And there is a case where precipitation occurs.

The acid to be contained in the acidic removing solution is not particularly limited, but it is required to be an acid which dissolves the oxide film, and examples thereof include sulfuric acid, phosphoric acid, hydrochloric acid and hydrofluoric acid. These acids may be used singly or in combination of two or more kinds. Or may be used in combination. Of these, sulfuric acid is preferable from the viewpoints of stability of the liquid to be removed and aggressiveness against aluminum or aluminum alloy materials.

The concentration of the acid in the removal liquid is not particularly limited, but is usually 10 g / L or more, preferably 15 g / L or more, and usually 500 g / L or less, preferably 300 g / L or less. If the concentration of the acid is too small, the oxide film may not melt and the effect may not be obtained. On the other hand, if the concentration is too large, the aluminum or aluminum alloy may be impregnated into the member other than the substrate.

(Alkaline removing liquid)

The metal constituting the metal salt or metal oxide contained in the alkaline removing liquid is not particularly limited as long as it is a metal substitutable with aluminum. However, it is preferably a metal having a lower ionization tendency than aluminum. For example, manganese, zinc, iron, cobalt, nickel , Tin, lead, copper, mercury, silver, platinum, gold, and palladium. Examples of the metal salt include water-soluble salts such as nitrates and sulfates of these metals. Among them, manganese and zinc are preferable because a reduction potential difference with aluminum, which is a base, is small.

The concentration of the metal salt or metal oxide to be used in the alkaline removing solution is not particularly limited, but it is usually at least 1 ppm (mg / L), preferably at least 10 ppm (mg / L) ) Or less, preferably 5,000 ppm (mg / L) or less. If the concentration of the metal salt or the metal oxide is too small, it may be necessary to replenish the metal or metal oxide in a case where it is not sufficiently substituted with the underlying aluminum. On the other hand, when the concentration is excessively large, when the aluminum or the aluminum alloy is an electrode patterned on the wafer, the member other than the aluminum or the aluminum alloy is infiltrated, or the aluminum or the aluminum alloy comes out of the member other than the aluminum or aluminum alloy And there is a case where precipitation occurs.

The solubilizing agent of the metal ion contained in the alkaline removing solution is not particularly limited, but ordinary chelating agents and chelating agents can be used. Specific examples thereof include hydroxycarboxylic acids and salts thereof such as glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid and heptogluconic acid, glycine, amino dicarboxylic acid, nitrilotriacetic acid, EDTA, Aminocarboxylic acids and salts thereof such as ethylenediamine diamine triacetic acid, diethylenetriaminepentaacetic acid, and polyaminopolycarboxylic acid; amine-based cheating agents such as HEDP, aminotrimethylphosphonic acid and ethylenediaminetetramethylphosphonic acid; Amine chelating agents such as salts, ethylenediamine, diethylenetriamine, triethylenetetramine and the like can be used.

The concentration of the solubilizing agent used in the alkaline removing solution is not particularly limited, but the total concentration of the solubilizing agent with respect to the metal salt to be used is preferably 0.5 to 10 (molar ratio), preferably 0.8 to 5 (molar ratio).

The alkali to be contained in the alkaline removing solution is not particularly limited, but it is required to be an alkali (base) which dissolves the oxide film. For example, alkaline metals such as LiOH, NaOH and KOH or trimethylammonium hydroxide (TMAH) And hydroxides of quaternary ammonium can be used. The amount of alkali to be added is an amount to bring the pH of the removed liquid into a prescribed range, that is, the pH is 10 to 13.5, preferably 11 to 13. If the pH is less than 10, the dissolution rate may significantly decrease. If the pH is more than 13.5, the dissolution rate may become too fast to be controlled.

It is preferable that the surfactant is included in the removal liquid for oxidation film in terms of imparting wettability to both the acidic removal liquid and the alkaline removal liquid. The surfactant to be used is not particularly limited, and examples thereof include nonionic surfactants such as polyethylene glycol, polyoxyethylene-oxypropylene block copolymer type surfactant, and anionic and cationic surfactants. In addition, Of these, nonionic and anionic types are preferable from the viewpoint of uniform processability. These may be used singly or in combination of two or more.

For example, in the case of using polyethylene glycol as the surfactant, the molecular weight is not particularly limited, but is usually 100 or more, preferably 200 or more, and usually 20,000 or less, preferably 6,000 or less. If the molecular weight is too large, the solubility may deteriorate. On the other hand, if the molecular weight is too small, wettability may not be imparted. As the polyethylene glycol, commercially available products can be used.

(Mg / L), preferably 10 ppm (mg / L) or higher as an upper limit and usually 5,000 ppm (mg / L) or lower as an upper limit, 2,000 ppm (mg / L) or less. If the concentration of the surfactant in the remover is excessively small, the effect of wettability obtained by adding the surfactant may be low. On the other hand, if the concentration is excessively large, the replacement metal is precipitated on a member other than aluminum or aluminum alloy .

It is preferable that the acidic removing solution and the alkaline removing solution are prepared in the form of an aqueous solution from the viewpoint of operational safety. However, it is preferable to use other solvents such as methanol, ethanol, IPA, It is also possible to use a solvent. These solvents may be used singly or in combination of two or more.

The immersing condition in immersing the object to be treated having aluminum or an aluminum alloy in the removing liquid is not particularly limited and may be set appropriately in consideration of the thickness of the aluminum oxide film to be removed and the like. 2 minutes or more, and usually not more than 20 minutes, preferably not more than 15 minutes, as an upper limit. On the other hand, if the immersion time is too long, the removal liquid enters the small hole of the replacement metal layer, and aluminum or aluminum alloy is eluted therefrom There is a risk of discarding.

The temperature for immersion is not particularly limited, but is usually 20 ° C or higher, preferably 25 ° C or higher, and usually 100 ° C or lower, preferably 95 ° C or lower as an upper limit. If the immersion temperature is too low, the oxide film may not be dissolved. On the other hand, if the immersion temperature is excessively high, members other than aluminum or an aluminum alloy may be invaded. In addition, when immersing, it is preferable to perform liquid agitation and rocking of the object to be treated from the viewpoint of uniform treatment.

In the case of using the above-mentioned removing liquid for the oxide film, the aluminum oxide film is removed, and a replacement metal layer of a metal substitutable with aluminum is formed. This replacement metal layer can be removed by an acidic liquid having an oxidizing action, Alternatively, the plating may be performed directly on the aluminum alloy or after the zinc substitution treatment or the palladium treatment.

When removing the substitution metal layer with an acidic liquid having an oxidizing action, an acidic liquid having an oxidizing action is used from the viewpoint of alleviating the reactivity with the underlying aluminum or aluminum alloy. In this case, as the acidic solution having an oxidizing action, an acid having an oxidizing action such as nitric acid or an aqueous solution thereof, an acid having no oxidizing action such as sulfuric acid, hydrochloric acid or the like or an aqueous solution thereof may contain an oxidizing agent such as hydrogen peroxide, sodium persulfate, Ammonium sulfate, potassium persulfate, and the like are preferably used. In this case, the acid has a function of dissolving the substituted metal, and the oxidizing agent has an action of alleviating the reactivity to the aluminum or aluminum alloy substrate. Hydrogen peroxide is preferable in that it is composed of hydrogen and oxygen in the oxidizing agent and becomes water when it is reduced, and sodium persulfate and potassium persulfate are preferable in view of stability and ease of handling.

Here, when nitric acid is used as the acid (and oxidizing agent), the amount of nitric acid in the solution (aqueous solution) is usually 200 ml / L or more, preferably 300 ml / L or more and usually 1,000 ml / Is not more than 700 ml / L. If the amount of nitric acid is too small, the oxidizing power is low and the reaction may not be stopped. Also, the case where the total amount of nitric acid is 1,000 ml / L is nitric acid.

When the oxidizing agent is used, the amount of the oxidizing agent in the solution is usually 50 g / L or more, preferably 75 g / L or more, and usually 500 g / L or less, preferably 300 g / L or less. If the amount of the oxidizing agent is too small, the oxidizing power is low and the reaction does not stop. On the other hand, if the amount is too large, the economical efficiency may be poor. The concentration of the acid such as hydrochloric acid or sulfuric acid used together with the oxidizing agent is usually 10 g / L or more, preferably 15 g / L or more, and the upper limit is usually 500 g / L or less, preferably 300 g / L or less. If the concentration of the acid is too small, the substitution metal layer may be difficult to dissolve. On the other hand, if the concentration is too large, there is a risk of erosion of members other than aluminum or aluminum alloy. The acid used herein is preferably non-oxidizing, but may be an oxidizing acid such as nitric acid, or an oxidizing acid may be mixed with a non-oxidizing acid.

In the dissolution treatment, the treatment time is not particularly limited. For example, the dissolution treatment may be performed for 5 to 300 seconds, and the dissolution treatment temperature may be, for example, 10 to 40 占 폚. During the dissolving treatment, the object to be plated may be oscillated even when stopped, and liquid stirring may be performed.

A first electroless nickel plating film is formed on the exposed aluminum or aluminum alloy by removing the aluminum oxide film. The first electroless nickel plating includes an electroless nickel-phosphorus plating bath containing a water-soluble nickel salt, a hypophosphoric acid and / or a salt thereof, and an organic carboxylic acid other than an aminocarboxylic acid and / or a salt thereof use.

Examples of the water-soluble nickel salt in the first electroless nickel-phosphorus plating bath include nickel sulfate, nickel chloride and nickel nitrate. The concentration of the water-soluble nickel salt in the plating bath is preferably 4 to 7 g / L as nickel.

Examples of salts of hypophosphorous acid include sodium hypophosphite, potassium hypophosphite and nickel hypophosphite. In this case, the concentration of hypophosphoric acid and / or its salt in the plating bath is preferably 0.1 to 0.3 mol / L.

On the other hand, the first electroless nickel-phosphorus plating bath is an organic carboxylic acid other than an aminocarboxylic acid and / or a salt thereof, that is, an organic carboxylic acid having a carboxyl group in the molecule but not having an amino group, Typically, it includes citric acid, acetic acid, succinic acid, malic acid and salts thereof, which are used as a complexing agent and a pH buffer in an electroless nickel-phosphorus plating bath. The concentration of the organic carboxylic acid and / or salt thereof other than the aminocarboxylic acid in the plating bath is preferably 1 to 50 g / L.

The first electroless nickel-phosphorus plating bath may contain an amino carboxylic acid and / or a salt thereof having an amino group and a carboxyl group in the molecule such as glycine, alanine, leucine, aspartic acid and glutamic acid. Examples of the salt thereof include a sodium salt, a potassium salt, an ammonium salt and a calcium salt. In this case, the concentration of the aminocarboxylic acid and / or its salt in the plating bath is preferably 0.05 to 2 mol / L.

The pH of the first electroless nickel-phosphorus plating bath is preferably 4.0 to 6.5. The pH can be adjusted with an alkali such as ammonia water or sodium hydroxide, or an acid such as sulfuric acid, hydrochloric acid or nitric acid.

The thickness of the first electroless nickel plating film to be formed is usually about 0.05 to 5 占 퐉 and the plating temperature and the plating time are selected in accordance with the film thickness of the plating film to be formed. The plating time is 1 to 30 minutes.

The first electroless nickel plating can be carried out directly on the surface of aluminum or an aluminum alloy and the surface of the aluminum or aluminum alloy is subjected to an activation treatment by zinc substitution treatment or palladium treatment or the like, A nickel plating treatment may be performed. As such an activation treatment, it is particularly preferable to form a zinc coating on the surface of aluminum or aluminum alloy by performing a zinc substitution treatment, in particular an alkaline zinc substitution treatment, from the viewpoint of improving the adhesion of the plating coating.

Here, as the zinc substitution treatment, specifically, a solution containing a zinc salt is used, and zinc is substituted and precipitated. In the case of the alkaline zinc substitution treatment, an alkaline alkaline solution is used. As the acidic zinc substitution treatment, a treatment for substituting zinc by using a solution containing an acidic zinc salt is carried out. . The palladium treatment can also be carried out by a known method in which palladium is substituted by precipitation using a solution containing a palladium salt.

[Second Nickel Plating Process]

In the present invention, a second electroless nickel plating film is formed on the surface of the first electroless nickel plating film formed in the first nickel plating process using a second electroless nickel-phosphorus plating bath. The second electroless nickel plating includes a water-soluble nickel salt, a hypophosphoric acid and / or a salt thereof, an aminocarboxylic acid and / or a salt thereof, an organic carboxylic acid other than the aminocarboxylic acid and a salt thereof Is used as an electroless nickel-phosphorus plating bath.

The water-soluble nickel salt and the hypophosphoric acid and / or the salt thereof in the second electroless nickel-phosphorus plating bath can be the same as those of the first electroless nickel-phosphorus plating bath described above.

On the other hand, examples of the aminocarboxylic acid include aminocarboxylic acids having an amino group and a carboxyl group in molecules such as glycine, alanine, leucine, aspartic acid and glutamic acid, and their salts include sodium salts, potassium salts, ammonium salts, . In this case, the concentration of the aminocarboxylic acid or its salt in the plating bath is preferably 0.2 to 1 mol / L. If the concentration of the aminocarboxylic acid or its salt is lower than 0.2 mol / L, the bath is cloudy, and if the concentration is higher than 1 mol / L, cracks may be generated in the plating film. Further, if the concentration is out of the range of 0.2 to 1 mol / L, the second electroless nickel-plated film can not be stably obtained.

In addition, the second electroless nickel-phosphorus plating bath does not contain an organic carboxylic acid other than an aminocarboxylic acid and a salt thereof. Namely, an organic carboxylic acid having a carboxyl group in the molecule but not having an amino group, for example, citric acid, acetic acid, succinic acid, malic acid or a salt thereof, which is usually used as a complexing agent or a pH buffer in an electroless nickel- Salts and the like.

In the second electroless nickel-phosphorus plating bath, it is more preferable to contain phosphorous acid and / or its salt, and the concentration of phosphorous acid and / or its salt in the plating bath is preferably 0.1 to 1 mol / L.

The pH of the second electroless nickel-phosphorus plating bath is preferably 5 to 6. The pH can be adjusted with an alkali such as ammonia water or sodium hydroxide, an acid such as sulfuric acid, hydrochloric acid or nitric acid, but no carboxylic acid other than aminocarboxylic acid is used as the pH adjusting agent.

The thickness of the second electroless nickel plating film to be formed is usually about 1 to 10 mu m and the plating temperature and the plating time are selected in accordance with the film thickness of the plating film to be formed, , And the plating time is 1 to 60 minutes.

After the second electroless nickel plating film is formed in this way, other plating films such as a gold plating film can be formed by a known method if necessary.

(For example, silicon, FRA (a substrate of a printed substrate)) may be used as the object to be processed which has aluminum or an aluminum alloy on at least the surface to which the present invention is applied, even if the entire object to be processed is formed of aluminum or an aluminum alloy. May be covered with aluminum or an aluminum alloy. The shape of the aluminum or aluminum alloy is not particularly limited, and can be suitably applied to, for example, a blank material, a rolled material, a cast material, and a coating film. When a coating film of aluminum or an aluminum alloy is formed on the surface of a non-aluminum material, the method of forming the coating film is not particularly limited. Examples of the method for forming the coating film include a vapor deposition method such as a vacuum vapor deposition method, a sputtering method, Is suitable.

The thickness of the coating film is usually not less than 0.5 mu m, preferably not less than 1 mu m, from the viewpoint of reliably retaining the aluminum or aluminum alloy substrate. The upper limit of the thickness is not particularly limited, but is usually 100 占 퐉 or less.

Aluminum or an aluminum alloy is not particularly limited as long as it is a component of the coating, but an alloy coating such as Al-Si (Si content 0.5 to 1.0 wt%) and Al-Cu (Cu content 0.5 to 1.0 wt% As shown in FIG.

(Example)

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. The epitaxial NPR used in the following examples is as follows.

EpiTas NPR-18

An electroless nickel plating bath containing 20 g / L of nickel sulfate, 25 g / L of sodium hypophosphite as a water soluble nickel salt, and 35 g / L of succinic acid as an organic carboxylic acid salt,

EpiTas NPR-22

An electroless nickel plating bath containing 25 g / L of nickel sulfate, 20 g / L of sodium hypophosphite, and 25 g / L of glycine as aminocarboxylic acids as a water soluble nickel salt, pH 5.6.

EpiTas NPR-29

An electroless nickel plating bath containing 20 g / L of nickel sulfate, 30 g / L of sodium hypophosphite as a water-soluble nickel salt, and 50 g / L of citric acid as an organic carboxylic acid salt,

Epithas NPR-28

An electroless nickel plating bath containing 20 g / L of nickel sulfate as a water-soluble nickel salt, 15 g / L of sodium hypophosphite, and 30 g / L of malic acid as an organic carboxylic acid salt.

[Example 1]

As the material to be plated, a silicon plate (thickness 0.15 mm) in which an aluminum layer with a thickness of 5 탆 was covered by a sputtering method was used, and this aluminum layer was subjected to the treatment shown in Table 1 in sequence. Table 2 shows the evaluation results of the warpage of the obtained plating film and the silicon plate.

process Chemical solution Condition (One)  Cleaner / Surface cleaning EpiTas MCL-16 ^*  50 ℃ for 5 minutes (2)  Remove oxide film  The following oxide film remover  50 ° C for 1 minute (3)  Remove smut 50% HNO ₃  20 ℃ for 30 seconds (4)  First kinetics treatment EpiTas MCT-17 ^*  20 ℃ for 10 seconds (5)  Remove Ginckite Film 50% HNO ₃  20 ℃ for 60 seconds (6)  Secondary kinetics treatment EpiTas MCT-17 ^*  20 ℃ for 30 seconds (7)  The first electroless nickel plating Epithas NPR-18 ^*  Thickness 1 탆 (8)  The second electroless nickel plating Epithas NPR-22 ^*  Film thickness 4 탆 (9)  Electroless gold plating (gold sulfite) EpiTas TDS-20 ^*  Film thickness 0.04 mu m

*: Manufactured by Uemura Kogyo K.K.

Loss of oxidation film: 2 g / L of zinc sulfate as a metal salt, 10 g / L of EDTA · 2Na as a solubilizing agent, 1 g / L of PEG (polyethylene glycol) -1000 as a surfactant, NaOH as an alkali, Adjusted aqueous solution

[Example 2]

Except that the first electroless nickel plating of Example 7 was conducted under the condition of a thickness of 1 탆 using a phosphorous type epitax NPR-29 (manufactured by Uemura Kogyo K.K.) Respectively. Table 2 shows the evaluation results of the warpage of the obtained plating film and the silicon plate.

[Example 3]

The procedure of Example 1 was repeated except that the first electroless nickel plating of Example 7 was carried out under the condition of a thickness of 1 mu m using a low-phosphorus type epitaxy NPR-28 (manufactured by Uemura Kogyo K.K.) Treatment. Table 2 shows the evaluation results of the warpage of the obtained plating film and the silicon plate.

[Comparative Example 1]

The treatment was carried out in the same manner as in Example 1 except that the first electroless nickel plating of (7) was not carried out. Table 2 shows the evaluation results of the warpage of the obtained plating film and the silicon plate.

[Comparative Example 2]

Except that the order of the first electroless nickel plating in (7) and the second electroless nickel plating in (8) were changed. Table 2 shows the evaluation results of the warpage of the obtained plating film and the silicon plate.

evaluation
Example Comparative Example One 2 3 One 2 Appearance of the second floor plating Good Good Good - Bad Crack in plating film none none none has exist has exist Warpage of silicon plate littleness littleness littleness - ^* - ^*

*: Unmeasured due to cracking

· Appearance of two-layer plating: It is good that there is no unadjustment and unevenness, and it is bad that there is not attachment or unevenness.

Crack of plating film: Observed by visual observation and stereoscopic microscope.

- Warping of the silicon plate: The wafer (silicon plate) after plating is cut to a size of 15 mm x 100 mm and the warp side is downward, and the warpage in the state where one side of the 15 mm side is grounded is measured with a digital vernier caliper Respectively. Smaller than 0.01 mm in height from the ground plane of the other 15 mm side was defined as " small "

Claims (10)

A surface treatment method of aluminum or an aluminum alloy for forming an electroless nickel plating film on an aluminum or aluminum alloy of an object to be treated having at least a surface of aluminum or an aluminum alloy, Removing the aluminum oxide film formed on the surface of the aluminum or aluminum alloy of the object to be treated and then removing the water soluble nickel salt, the hypophosphoric acid and / or its salt and the organic carboxylic acid other than the aminocarboxylic acid A first nickel plating step of forming a first electroless nickel plating film by using a first electroless nickel plating bath comprising a complex oxide and / or a salt thereof, and Wherein the surface of the first electroless nickel plating film contains a water-soluble nickel salt, a hypophosphoric acid and / or a salt thereof, an aminocarboxylic acid and / or a salt thereof, and an organic carboxylic acid other than an aminocarboxylic acid And a second nickel plating step of forming a second electroless nickel plating film by using a second electroless nickel plating bath not containing the salt, characterized in that the surface treatment of aluminum or an aluminum alloy Way. The surface treatment method according to claim 1, wherein the film thickness of the first electroless nickel plating film is 0.05 to 5 탆. The surface treatment method according to claim 1, wherein the pH of the first electroless nickel-phosphorus plating bath is 4.0 to 6.5. The method according to claim 1, wherein the first electroless nickel-phosphorus plating bath further comprises at least one selected from the group consisting of aminocarboxylic acids and salts thereof. The method according to claim 1, wherein the first nickel plating step comprises immersing the object to be treated in a removing solution for an aluminum oxide film containing a metal capable of replacing aluminum to remove the aluminum oxide film and replacing aluminum contained in the removing solution A step of forming a substitution metal layer of a possible metal, A step of removing the substituted metal layer with an acidic liquid having an oxidation action, and And a step of forming a first electroless nickel plating film on the exposed aluminum or aluminum alloy after the replacement metal layer is removed. The surface treatment method according to claim 5, wherein the aluminum oxide film removing liquid contains a salt of a metal capable of substituting aluminum and an acid. The surface treatment method according to claim 6, wherein the metal is zinc, iron, cobalt, nickel, tin, lead, copper, mercury, silver, platinum, gold or palladium. The method according to claim 5, wherein the aluminum oxide film removing liquid contains a salt or oxide of a metal capable of substituting aluminum, a solubilizing agent for the metal ion, and an alkali, and has a pH of 10 to 13.5 Surface treatment method. The surface treatment method according to claim 8, wherein the metal is manganese, zinc, iron, cobalt, nickel, tin, lead, copper, mercury, silver, platinum, gold or palladium. The surface treatment method according to claim 6 or 8, wherein the aluminum oxide film removing liquid further contains a surfactant.