TWI419995B - Method for surface treatment of aluminum or aluminum alloy - Google Patents

Description

Surface treatment method of aluminum or aluminum alloy

The invention relates to a surface treatment method for aluminum or aluminum alloy, in particular to a surface treatment method for aluminum or aluminum alloy when a UMB (metal underlayer) or a bump is formed by electroplating on a wafer.

Conventionally, as a method of forming a UMB or a bump on a circle, an aluminum film electrode for patterning on a wafer can be subjected to zinc substitution treatment to form a zinc film, and then a bump is formed by electroless plating. The method, in place of the above zinc substitution treatment, after palladium treatment, forming a bump by electroless nickel plating, or directly replacing the surface of the aluminum thin film electrode with nickel, forming a bump by self-catalytic type electroless nickel plating Method, etc.

Further, UMB or bumps of the electroless nickel-plated film are formed by such a method, and in order to improve electrical characteristics, particularly to lower the electric resistance, electroless copper plating is applied to the electroless nickel plating film. At this time, since the electroless nickel plating film has no catalytic property and cannot be directly electrolessly plated on the electroless nickel plating film, a copper substitution treatment for imparting catalytic properties to the electroless nickel plating film has conventionally been applied.

However, this copper substitution treatment easily erodes the electroless nickel plating film, and as a result, the underlayer (aluminum or aluminum alloy) attacks (erosion), and the adhesion of the electroless copper plating film formed by the copper substitution treatment becomes low.

Invention disclosure

In view of the above, the present invention provides an electroless nickel plating film formed on aluminum or an aluminum alloy, and further forms an electroless copper plating film on the electroless nickel plating film to treat the surface of the aluminum or aluminum alloy. However, it is intended to etch the electroless nickel-plated film to impart good catalytic properties, form an electroless copper plating film, and provide a surface treatment method for aluminum or aluminum alloy having high adhesion to the electroless copper plating film.

In order to achieve the above object, the inventors of the present invention have found that an electroless nickel plating film is formed on aluminum or an aluminum alloy, and an electroless copper plating film is formed on the electroless nickel plating film to treat the surface of the aluminum or aluminum alloy. When an electroless copper plating film is formed on the surface of the electroless nickel plating film by substitution plating or electroless plating to form Ag, Au, Pd, Pt, Rh or an alloy thereof, an electroless copper plating film can be provided. The electrocatalytic copper plating film having good catalytic properties and the resulting electroless copper plating film have high adhesion, and the present invention has been completed.

Accordingly, the present invention provides a surface treatment method of the following aluminum or aluminum alloy.

(1): forming an electroless nickel-plated film on at least the aluminum or aluminum alloy having a treated object of aluminum or aluminum alloy on the surface, and further forming an electroless copper-plated film of aluminum or aluminum on the electroless nickel-plated film The surface treatment method of the alloy includes an aluminum oxide film formed on the surface layer of the aluminum or aluminum alloy on which the object to be treated is removed, and an electroless nickel plating film is formed on the aluminum or aluminum alloy. Nickel plating step, Forming an intermediate plating step of Ag, Au, Pd, Pt, Rh or an intermediate plating film of the alloy on the surface of the electroless nickel-plated film by substitution plating or electroless plating, and surface of the intermediate plating film A surface treatment method for forming an aluminum or aluminum alloy characterized by a copper plating step of an electroless copper plating film.

(2) The nickel plating step includes a removal liquid for immersing the object to be treated in an aluminum oxide film containing a metal which can replace aluminum, removing the aluminum oxide film, and forming a metal which can replace aluminum in the removal liquid. The step of replacing the metal layer, the step of removing the substituted metal layer by an acidic liquid having oxidation, and the step of removing the aluminum or aluminum alloy exposed by the substituted metal layer to form an electroless nickel plating film (1) The surface treatment method described.

(3) The surface treatment method described in (2), wherein the aluminum oxide film removal liquid contains a salt of a metal which can replace aluminum and an acid.

(4): The above-mentioned aluminum oxide film removal liquid contains a salt of a metal which can replace aluminum Or a surface treatment method according to (2) characterized by having an oxide, a solubilizing agent for the metal ion, and a base, and having a pH of 10 to 13.5.

(5): The surface treatment method described in (3) or (4), wherein the aluminum oxide film removal liquid system further contains a surfactant.

According to the present invention, an electroless nickel plating film is formed on aluminum or an aluminum alloy, and an electroless copper plating film is formed on the electroless nickel plating film, and when the surface of the aluminum or aluminum alloy is treated, good catalytic properties can be imparted. The electroless copper plating film is formed, and the obtained electroless copper plating film is a film having high adhesion.

The best form for implementing the invention

The invention is illustrated in more detail below.

The surface treatment method of the present invention forms an electroless nickel plating film on at least the aluminum or aluminum alloy having a treated object of aluminum or aluminum alloy on the surface, and further forms an electroless copper plating film on the electroless nickel plating film. a surface treatment method for aluminum or aluminum alloy, comprising the step of forming an aluminum oxide film formed on the surface layer of the aluminum or aluminum alloy of the object to be treated, and forming a nickel plating film on the aluminum or aluminum alloy to form an electroless nickel plating film, The surface of the electroless nickel-plated film is formed by substitution plating or electroless plating to form an intermediate plating step of Ag, Au, Pd, Pt, Rh or an intermediate plating film of the alloys, and forming a surface of the intermediate plating film. Electroless copper plating film Copper plating stepper. The following is a description of each of the above steps.

[Ni plating step]

In the present invention, the aluminum oxide film formed on the surface layer of the aluminum or aluminum alloy of the object to be treated is removed, and an electroless nickel plating film is formed on the aluminum or aluminum alloy to remove the aluminum oxide film, and the aluminum oxide can be removed by a conventionally known method. The film is formed on the exposed aluminum or aluminum alloy to form an electroless nickel plating film.

At this time, the object to be treated is immersed in a removal liquid for an aluminum oxide film containing a metal which can replace aluminum, and the aluminum oxide film is removed, and a substituted metal layer containing a metal which can replace aluminum in the removal liquid is formed to have an acidity of oxidation. The liquid is removed from the substituted metal layer, and an electroless nickel plating film may be formed on the aluminum or aluminum alloy exposed by the replacement metal layer.

As the removal liquid for the aluminum oxide film, a salt containing a metal which can replace aluminum, an acid, a salt-containing compound (acid removal liquid), or a metal which can replace aluminum can be suitably used or oxidized. The material, the metal ion solubilizing agent, the alkali, and the surfactant are preferably used, and the pH is 10 to 13.5 (alkaline removing liquid).

(acidic removal solution)

The metal constituting the metal salt contained in the acid removal liquid is not particularly limited as long as it can replace the metal of aluminum. However, a metal having a smaller ionization tendency than aluminum is preferable, and examples thereof include zinc, iron, and cobalt. And nickel, tin, lead, copper, mercury, silver, platinum, gold, palladium, etc., as the above-mentioned metal salt, a water-soluble salt such as a nitrate or a sulfate of the metal can be exemplified. In particular, remove the liquid Sulfate is preferred for reasons of stability or less aggressiveness to aluminum or aluminum alloy materials. These may be used alone or in combination of two or more. Among them, silver, nickel, and copper are less likely to precipitate in other parts, and therefore, copper and silver have a much smaller ionization tendency than aluminum. Therefore, it is easier to carry out the substitution reaction and shorten the etching treatment time.

The metal salt concentration to be used as the acid removal liquid is not particularly limited, and the amount of the metal is usually 1 ppm or more, preferably 10 ppm or more, and the upper limit is usually 10,000 ppm or less, and preferably 5,000 ppm or less. When the concentration of the metal salt is too small, it cannot be sufficiently substituted with the aluminum of the underlying layer, and metal salt replenishment must occur. On the other hand, when the concentration is too large, when aluminum or an aluminum alloy is applied to the electrode patterned on the wafer, the member other than the aluminum or aluminum alloy underlayer is eroded, or the member other than the aluminum or aluminum alloy underlayer is precipitated.

The acid contained in the acid-removing liquid is not particularly limited, and is an acid which dissolves the oxide film, and examples thereof include sulfuric acid, phosphoric acid, hydrochloric acid, and hydrofluoric acid. These may be used alone or in combination of two or more. Among them, sulfuric acid is preferred from the viewpoints of the stability of the removal liquid or the less aggressiveness to 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 5 g/L or more, and the upper limit is usually 500 g/L or less, and preferably 300 g/L or less. When the concentration of the acid is too small, the oxide film cannot be dissolved and the effect is not obtained. On the other hand, when the concentration is too large, the member other than the aluminum or aluminum alloy underlayer is eroded.

(alkaline removal solution)

The metal constituting the metal salt or the metal oxide contained in the alkaline removal liquid is not particularly limited as long as it can replace the metal of aluminum, but it is preferably a metal having a smaller ionization tendency than aluminum. Manganese, zinc, iron, cobalt, nickel, tin, lead, copper, mercury, silver, platinum, gold, palladium, etc., as the metal salt, for example, a water-soluble salt such as a metal nitrate or a sulfate. Among them, the reduction potential difference between manganese, zinc and aluminum of the bottom layer is preferably small.

The concentration of the metal salt or the metal oxide used as the alkaline removal liquid is not particularly limited, and the metal amount is usually 1 ppm (mg/L) or more, preferably 10 ppm (mg/L) or more, and the upper limit is usually It is preferably 10,000 ppm (mg/L) or less and 5,000 ppm (mg/L) or less. When the concentration of the metal salt or the metal oxide is too small, it cannot be sufficiently substituted with the aluminum of the underlayer, and it is necessary to supply the metal salt or the metal oxide. On the other hand, when the concentration is too large, when the electrode is patterned on an aluminum or aluminum alloy wafer, the member other than the aluminum or aluminum alloy underlayer is eroded, or the member other than the aluminum or aluminum alloy underlayer is precipitated.

The solubilizing agent for the metal ion contained in the alkaline removing liquid is not particularly limited, and a usual complexing agent or a chelating agent can be used. Specifically, a hydroxycarboxylic acid such as glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, heptanoic acid or the like and the salt, glycerin, aminodicarboxylic acid, nitrogen triacetic acid, EDTA can be used. (Ethylenediaminetetraacetic acid), hydroxyethyl-ethylidene diamine triacetic acid, di-ethyltriamine pentaacetic acid, polyaminopolycarboxylic acid, and the like, and the salt, HEDP (hydroxyethylidene II) a phosphorous acid-based chelating agent such as phosphoric acid), aminotrimethylsulfonic acid, ethyldiaminetetramethylsulfonic acid, etc., and the salt, ethylidene diamine An amine-based chelating agent such as diethyltriamine or tri-ethyltetramine.

The concentration of the solubilizing agent used as the alkaline removing liquid is not particularly limited, but the total concentration of the solubilizing agent is 0.5 to 10 (mole ratio) with respect to the metal salt to be used, and is 0.8 to 5 ( Moerby) is appropriate.

The alkali contained in the alkaline removal liquid is not particularly limited, but it is preferably an alkali which dissolves the oxide film, and examples thereof include alkali metals such as LiOH, NaOH, and KOH, or ammonium trimethylammonium hydroxide (TMAH). a hydroxide of a quaternary ammonium such as a base or the like. Further, the amount of the base added is such that the pH of the removal liquid is within a predetermined range, that is, the pH is 10 to 13.5, and preferably 11 to 13. If the pH is less than 10, the dissolution rate is significantly lowered. If the pH exceeds 13.5, the dissolution rate is too fast to be controlled.

In the above-mentioned oxide film-removing liquid, it is preferable to use a surfactant in the viewpoint of imparting water wettability to any of the acid-removing liquid and the alkaline-removing liquid. The surfactant to be used is not particularly limited, and examples thereof include polyethylene glycol and polyethylene oxide. The nonionic surfactant of the polypropylene oxide block copolymerization type active agent, and other anionic and cationic surfactants are preferred in terms of uniform treatment properties, and nonionic and anionic types are preferred. These may be used alone or in combination of two or more.

For example, polyethylene glycol is used as the surfactant, and the molecular weight is not particularly limited, but is usually 100 or more, preferably 200 or more, and the upper limit is usually 20,000 or less, and preferably 6,000 or less. When the molecular weight is too large, the solubility is deteriorated. On the other hand, if the molecular weight is too small, water wettability cannot be imparted. Further, as the polyethylene glycol, a commercially available product can be used.

In addition, the concentration in the removal liquid as a surfactant is not particularly The amount is usually 1 ppm (mg/L) or more, preferably 10 ppm (mg/L) or more, and the upper limit is usually 5,000 ppm (mg/L) or less, and preferably 2,000 ppm (mg/L) or less. When the concentration of the surfactant in the removal liquid is too small, the obtained water wettability is low. On the other hand, when the concentration is too large, a substitution metal is precipitated on a member other than aluminum or aluminum alloy.

Further, in the above-mentioned oxide film removal liquid-based acid removal liquid and alkaline removal liquid, it is preferable to prepare an aqueous solution from the viewpoint of handling safety, but other solvents such as methanol, ethanol, and IPA may be used. Propanol), etc., or a mixed solvent with water. Further, these solvents may be used alone or in combination of two or more.

The immersion conditions in the case of immersing the object to be treated having aluminum or an aluminum alloy in the removal liquid are not particularly limited, but may be appropriately set in consideration of the thickness of the aluminum oxide film to be removed, etc., but usually 1 minute or longer and 2 minutes. The above is suitable, and the upper limit is usually 20 minutes or less, preferably 15 minutes or less. When the immersion time is too short, the oxidized film is not sufficiently removed. On the other hand, when the immersion time is too long, the removal liquid is infiltrated from the pores of the substituted metal layer, and the aluminum or aluminum alloy is eluted.

Further, the temperature at the time of immersion is not particularly limited, but is usually 20° C. or higher, preferably 25° C. or higher, and the upper limit is usually 100° C. or lower, and particularly preferably 95° C. or lower. When the immersion temperature is too low, the oxide film cannot be dissolved. On the other hand, if the immersion temperature is too high, the member other than aluminum or aluminum alloy is invaded. Further, in the case of immersion, it is preferred to carry out liquid agitation or shaking of the object to be treated from the viewpoint of uniform treatment.

When the above oxide film removing liquid is used, the aluminum oxide film is removed, and Forming a substituted metal layer which can replace the metal of aluminum. The substituted metal layer can be removed by an acidic liquid having an oxidation effect, and is directly or subjected to a zinc substitution treatment or a palladium treatment on the aluminum or aluminum alloy from which the substituted metal layer is removed. .

When the substituted metal layer is removed by an acidic liquid having an oxidizing action, an acidic liquid for oxidation can be used from the viewpoint of alleviating the reactivity of the aluminum or aluminum alloy of the underlayer. In this case, an acid having an oxidizing action is used for an acid having an oxidizing action such as nitric acid or an acid having no oxidizing action such as the aqueous solution, sulfuric acid or hydrochloric acid, or one or more of the aqueous solution. An oxidizing agent such as hydrogen peroxide, sodium persulfate, ammonium persulfate or potassium persulfate is preferred. At this time, the acid has an effect of dissolving the substituted metal, and the oxidizing agent has a function of alleviating the reactivity with the aluminum or aluminum alloy underlayer. Further, the oxidizing agent is formed of hydrogen and oxygen, and it is preferable to use hydrogen peroxide as a water, and it is preferable to use hydrogen peroxide, and it is preferable to use sodium persulfate or potassium persulfate from the viewpoint of stability and easy 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 mI/L or more, preferably 300 mI/L or more, and the upper limit is usually 1,000 mI/L or less, and 700 mI/ Below L is appropriate. If the amount of nitric acid is too small, the oxidizing power is low and the reaction does not stop. In addition, the so-called nitric acid of 1,000 mI/L means that the total amount is nitric acid.

Further, when an 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 the upper limit is usually 500 g/L or less, and preferably 300 g/L or less. When 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 economy is poor. In addition, 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 is preferably 15 g/L or more, and the upper limit is usually 500 g/L or less, and preferably 300 g/L or less. If the concentration of the acid is too small, it is difficult to dissolve the substituted metal layer. On the other hand, if the concentration is too large, the member other than aluminum or aluminum alloy is eroded. Further, the acid used herein is preferably non-oxidizing, but it may be an oxidizing acid such as nitric acid, or may be used by mixing an oxidizing acid or a non-oxidizing acid.

The dissolution treatment is not particularly limited as the treatment time. For example, the dissolution treatment may be carried out for 5 to 300 seconds, and the dissolution treatment temperature may be, for example, 10 to 40 ° C. Further, in the dissolution treatment, the electroplated treated material may be stationary, or may be shaken, or may be stirred by liquid.

The aluminum oxide film is removed, and the exposed aluminum or aluminum alloy forms an electroless nickel plating film. As the electroless nickel plating, a known electroless nickel plating bath may be used, and for example, an electroless nickel plating bath containing nickel sulfate, an organic acid (succinic acid, malic acid, citric acid, etc.) or sodium hypophosphite may be used. A commercially available electroplating bath can be used.

The film thickness of the electroless nickel plating film is usually about 1 to 20 μm, and the film thickness of the plating film is selected, and the plating temperature and the plating time are selected. Usually, the plating temperature is 50 to 95 ° C, and the plating time is 5 to 120 minutes.

Further, the electroless nickel plating may be applied directly to the surface of the aluminum or the aluminum alloy, or may be subjected to an electroless nickel plating treatment by subjecting the surface of the aluminum or aluminum alloy to activation treatment by a zinc substitution treatment or a palladium treatment. As such an activation treatment, in particular, a zinc substitution treatment in which a zinc coating film is formed on the surface of aluminum or an aluminum alloy by applying an alkali zinc substitution treatment is preferable from the viewpoint of improving the adhesion of the plating film.

Here, as the zinc substitution treatment, specifically, a treatment in which a zinc-containing salt solution is used and a zinc is substituted for precipitation is used. In the case of the alkali zinc substitution treatment, an alkaline zinc acid solution is used, and when the acid zinc substitution treatment is used, a solution containing an acidic zinc salt is used to carry out the treatment of zinc precipitation, and these methods can be carried out by a known method. Further, as a treatment for palladium, a solution in which palladium salt is used as a substitute for precipitation of palladium can be carried out by a known method.

[Intermediate plating step]

In the present invention, Ag, Au, Pd, Pt, Rh or an intermediate plating film of these alloys is formed on the surface of the electroless nickel plating film formed by the above nickel plating step by substitution plating or electroless plating. For the substitution plating or electroless plating, a known substitution plating bath or an electroless plating bath containing Ag, Au, Pd, Pt or Rh may be used, and for example, a metal (Ag, Au, Pd, Pt, Rh) salt may be contained. a substitutional plating bath of an inorganic acid (sulfuric acid, hydrochloric acid, etc.), an organic acid (succinic acid, malic acid, citric acid, etc.), a metal (Ag, Au, Pd, Pt, Rh) salt, a complexing agent (organic acid, An electroless plating bath such as EDTA or the like, a reducing agent (formic acid, sodium hypophosphite, hydrazine, etc.) may be used, and a commercially available electroplating bath may also be used.

The film thickness of the intermediate plating film is usually 0.005 to 1.0 μm, preferably about 0.01 to 0.5 μm, and the film thickness of the plating film is matched, and the plating temperature and the plating time are selected. Usually, the plating temperature is 30 to 80 ° C, and the plating time is 10 seconds to 10 minutes. The intermediate plating film of Ag, Au, Pd, Pt, Rh or these alloys is formed, and an electroless copper plating film is formed by a copper plating step to be described later, whereby good catalytic properties can be imparted, and an electroless copper plating film can be formed.

[copper plating step]

In the present invention, the surface of the film is plated in the middle of the intermediate plating step to form an electroless copper plating film. For the electroless copper plating, a known electroless copper plating bath can be used, and for example, an electroless copper plating bath containing copper sulfate, a complexing agent (tartaric acid, EDTA, etc.), formal water or the like can be used, and a commercially available one can also be used. Electroplating bath.

The film thickness of the formed electroless copper plating film is usually about 0.05 to 10 μm, and the film thickness of the plating film is matched, and the plating temperature and the plating time are selected. Usually, the plating temperature is 20 to 75 ° C, and the plating time is 5 minutes to 6 hours.

The object of the present invention having at least an object having aluminum or an aluminum alloy on the surface may be formed of aluminum or an aluminum alloy as a whole, or may be coated with aluminum or aluminum alloy in a non-aluminum material (for example, FRA, FRA). All or part of the surface of the substrate (printed substrate). In addition, the form of the aluminum or the aluminum alloy is not particularly limited, and can be suitably applied to, for example, a green material, a rolled material, a cast material, a film, or the like. In addition, when a film of aluminum or an aluminum alloy is formed on the surface of a non-aluminum material, the method of forming the film is not particularly limited, but as the method of formation, for example, a vacuum evaporation method, a sputtering method, an ion plating method, or the like is used. Gas phase plating is suitable.

The thickness of the film is preferably 0.5 μm or more and 1 μm or more from the viewpoint of reliably leaving the aluminum or aluminum alloy underlayer. Further, the upper limit of the thickness is not particularly limited, but is usually 100 μm or less.

Further, the film component is not particularly limited as long as it is aluminum or an aluminum alloy, and for example, A1-si (Si content is 0.5 to 1.0). An alloy film such as wt%) or A1-Cu (Cu content: 0.5 to 1.0% by weight) may be used.

Example

The following are examples and comparative examples, which are specifically described in the present invention, but the present invention is not limited to the following examples.

[Example 1]

As the electroplated material, a crucible having a thickness of 5 μm in the aluminum layer was sputter-coated, and the aluminum layer was treated as shown in Table 1 in that order. Regarding the characteristics of the obtained plating film, the evaluation results are shown in Table 2.

Oxidation film removal liquid: containing 2 g/L of zinc sulfate as a metal salt, 10g/L EDTA as a solubilizing agent. 2Na, PEG (polyethylene glycol)-1000 as a surfactant, 1 g/L, NaOH as a base, adjusted to an aqueous solution of pH 12.4

[Embodiment 2]

In addition to gold plating (gold sulfite) instead of (8), gold plating (gold cyanide) (medicine solution: Epitas TDL-20 (manufactured by Uemura Industrial Co., Ltd.), condition: film thickness: 0.05 μm) Example 1 was treated in the same manner. Regarding the characteristics of the obtained plating film, the evaluation results are shown in Table 2.

[Example 3]

In the same manner as in the first embodiment except that the gold plating (gold sulfite) was replaced by (8), electroless plating Pd (chemical liquid: Epitas TFP-30 (manufactured by Uemura Kogyo Co., Ltd.), condition: film thickness: 0.06 μm) The ground is treated. Regarding the characteristics of the obtained plating film, the evaluation results are shown in Table 2.

[Comparative Example 1]

The treatment was carried out in the same manner as in Example 1 except that the gold plating (gold sulfite) was not carried out in (8). Regarding the characteristics of the obtained plating film, the evaluation results are shown in Table 2.

[Comparative Example 2]

In addition to (8) substituted gold plating (gold sulfite) as a copper substitution treatment (chemical solution: copper sulfate is 0.5g / L sulfuric acid (62.5%) 10g / L, conditions: 20 ° C 30 The treatment was carried out in the same manner as in Example 1 except for the second. Regarding the characteristics of the obtained plating film, the evaluation results are shown in Table 2.

. Appearance of electroless copper plating film: Observed by visual inspection and stereoscopic microscope, no non-adhesion and unevenness were good, and unattached and unevenness was not preferable. . Adhesiveness: The enamel plate was broken by the plating film, and the plated film was not peeled off and was broken, and the Ni/Cu peeling was not good. . Erosion of the bottom layer: no erosion of the bottom layer is "none", and erosion of the bottom layer is "have".

Claims (7)

An aluminum or aluminum alloy surface treatment method for forming an electroless nickel plating film on the aluminum or aluminum alloy having at least a processed object of aluminum or aluminum alloy on the surface, and further forming an electroless plating on the electroless nickel plating film A surface treatment method for aluminum or aluminum alloy of a copper-plated film, comprising: removing a liquid for etching an aluminum oxide film containing a metal which can replace aluminum, and removing the surface of the aluminum or aluminum alloy surface of the object to be treated a step of forming the aluminum oxide film, forming a substituted metal layer of the metal substituted for aluminum in the removal liquid, a step of removing the substituted metal layer by the acidic liquid having oxidation, and exposing the layer of the replacement metal a nickel plating step of forming an electroless nickel plating film on the aluminum or aluminum alloy, forming Ag, Au, Pd, Pt, Rh or the like on the surface of the electroless nickel plating film by substitution plating or electroless plating The intermediate plating step of the intermediate plating film of the alloy, and the surface of the intermediate plating film form a copper plating step of the electroless copper plating film. The surface treatment method according to the first aspect of the invention, wherein the aluminum oxide film removal liquid contains a salt of a metal which can replace aluminum and an acid. The surface treatment method according to the first aspect of the invention, wherein the aluminum oxide film removal liquid contains a salt or an oxide of a metal which can replace aluminum, a solubilizing agent for the metal ion, and a base, and has a pH of 10 ~13.5. For example, in the surface treatment method of claim 2 or 3, The aluminum oxide film-removing liquid system further contains a surfactant. The surface treatment method of claim 2, wherein the metal which can replace aluminum is zinc, iron, cobalt, nickel, tin, lead, copper, mercury, silver, platinum, gold, palladium. For example, in the surface treatment method of claim 3, the metal which can replace aluminum is manganese, zinc, iron, cobalt, nickel, tin, lead, copper, mercury, silver, platinum, gold, palladium. The surface treatment method according to claim 1, wherein the electroless nickel plating film is formed by directly or after a zinc substitution treatment on the aluminum or aluminum alloy exposed by removing the substitution metal layer.