JPH06122993A - Method for plating amorphous alloy film - Google Patents

Abstract

PURPOSE:To provide a plating method capable of controlling the composition of an amorphous alloy film contg. plural kinds of metals and metalloid elements, formed from an electroless plating bath. CONSTITUTION:A shaft is dipped in an electroless plating bath contg. plural kinds of metal ions, a reducing agent and metalloid elements and plated. In this case, as the amt. of metalloid elements to be added is increased, the metalloid element content of the film to be formed increases, the film is further made amorphous, and the contents of the plural metals are significantly changed. Accordingly, a current is applied with a base material as the cathode in electroless plating to change the contents of plural metals in the amorphous alloy film, and hence the contents of metals are not fluctuated when the metalloid elements are increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for plating an amorphous alloy film. The amorphous alloy film of the present invention is suitable as a soft magnetic film used for magnetic heads, transformers, sensors and the like.

[0002]

2. Description of the Related Art Magnetostriction in which a crystalline or amorphous soft magnetic film is adhered to a shaft, magnetic anisotropy is given to the soft magnetic film, and a change in magnetic characteristics of the soft magnetic film due to twisting of the shaft is magnetically detected. Type torque sensors are known. For example, the following method has been proposed as a method for manufacturing a soft magnetic film used in such a magnetostrictive torque sensor.

Japanese Unexamined Patent Publication No. 59-164931 proposes to form a crystalline soft magnetic film by nickel electroplating. In addition, for example, sodium hypophosphite is used as a reducing agent and Fe ions are used. An electroless plating method is known in which a crystalline Fe—Ni—P soft magnetic film is formed by immersing a pretreated substrate in an ammonia alkaline tartaric acid bath containing nickel ions for several hours.
Compared to the crystalline soft magnetic film, the amorphous soft magnetic film formed by the sputtering method or the vacuum quenching method has no crystal defects that hinder the domain wall movement, and thus is more excellent as the soft magnetic film of the magnetostrictive torque sensor. Is known to exist.

Further, it is known that by increasing the concentration of boron (or metalloid element) in the electroless plating bath, boron atoms inhibit crystal growth, and the crystal structure of the film can be made finer and amorphous. There is.

[0005]

However, it is conceivable to add boron when the soft magnetic film is formed by the above-mentioned conventional electroless plating method to make the crystal fine.
It was not known whether an Fe-Ni-B amorphous soft magnetic film suitable as a soft magnetic film could be actually manufactured by this method.

According to experiments conducted by the present inventor, when boron is added to an electroless plating bath to form an amorphous soft magnetic film (for example, containing 3 wt% of boron), the iron content in the obtained amorphous film is roughly the same. Since it is as small as 20 wt% or less,
It has a low saturation magnetic flux density and has a drawback that it causes a decrease in output sensitivity as a soft magnetic film for a magnetostrictive torque sensor as compared with a crystalline soft magnetic film.

Further, if the amount of boron added in the plating bath is reduced, an amorphous soft magnetic film (for example, 0.5 wt% boron) is formed.
Iron content (about 35%) can be increased, saturation magnetic flux density can be improved, and output sensitivity can be improved, but the soft magnetic film is crystallized because the amount of boron in the soft magnetic film is small. was there. The present invention has been made in view of the above problems, and provides a plating method capable of composition control in an alloy film having a microcrystalline structure or an amorphous structure containing a plurality of types of metals and metalloid elements formed from an electroless plating bath. The task to be solved is to do.

[0008]

The plating method of the present invention comprises:
A method of immersing a base material in an electroless plating bath containing a plurality of types of metal ions and a reducing agent containing a metalloid element, and plating an amorphous alloy film containing the plurality of metals and the metalloid element on the surface of the base material. In the above, the composition of the alloy film is adjusted by energizing the base material as a cathode.

In a preferred embodiment, the energization enriches the metal having a smaller affinity with the metalloid element. As the reducing agent, sodium borohydride, dimethylamine borane, sodium hypophosphite and the like can be used. Iron is suitable as one type of the metal ions in the amorphous soft magnetic film.

Nickel or cobalt is suitable as another type of the above metal ions in the amorphous soft magnetic film.

[0011]

[Operation] According to the experiment, when electroless plating is performed by immersing the shaft in an electroless plating bath containing a plurality of kinds of metal ions, a reducing agent and a metalloid element, a substance containing a metalloid element (called a metalloid compound) As the addition amount of is increased, the composition ratio of the metalloid element in the formed film increases, and along with that, the crystal structure becomes finer and amorphous. It is considered that this is because the crystal growth is hindered because the affinity between atoms of other species (particularly with the metalloid element) is larger than the affinity between atoms of the same species. In particular, a metalloid element having a relatively small atomic weight such as boron has a large strain in a unit cell formed between a metal atom having a large atomic weight and inhibits crystal growth. However, it has been found that such an increase in the amount of the metalloid compound added remarkably changes the composition ratio of the above-described plurality of kinds of metals to be electroless plated.

This is because there is a difference in affinity between the metalloid element and the above-mentioned plurality of kinds of metals, and for this reason, for example, due to an increase in the metalloid element on the film surface or the like, a large number of metal atoms having a strong affinity with it are deposited (adsorption). Because
It is considered that the composition of the formed alloy film changes.
For example, when electroless plating of an Fe-Ni-B amorphous soft magnetic film is performed, when the amount of B added is increased, Ni in the amorphous film is remarkably increased and Fe is remarkably decreased. Therefore, when electricity is applied, that is, when an electrolytic reaction is performed with the shaft on which the amorphous film is to be formed as a cathode, the metal ion having a relatively low affinity with the metalloid element is also accelerated by the electric field, and the affinity with the metalloid element is relatively low. It was found that the composition ratio of the other metal was improved. That is, it has been found that the composition of the amorphous soft magnetic film formed of the metalloid element for forming the microcrystalline structure or the amorphous structure can be changed to a suitable ratio by energization.

[0013]

According to the experiment, the shaft is immersed in an electroless plating bath containing ions of a plurality of kinds of metals, a reducing agent and a metalloid element, and the surface of the shaft is made of an amorphous soft metal containing the plurality of metals and the metalloid element. It has been found that the composition of the amorphous soft magnetic film can be adjusted by energizing the shaft with the shaft as a cathode when forming the magnetic film.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples. Figure 1
And as shown in FIG. 2, the material is S45C and the diameter is 20 m.
m, a helical spline groove (see FIG. 2) 2 is previously formed on the surface of a shaft 1 having a length of 150 mm,
After degreasing with an alkaline degreasing liquid or the like, activation was performed with dilute hydrochloric acid. The lead angles of the helical spline grooves 2 are opposite to each other.

Next, after washing with water, electroless plating is performed to obtain about 2 μm.
Amorphous underlayer nickel film (Ni-P
A film (not shown) is formed, and then electric current and electroless plating are performed to form iron, nickel and boron (Fe-Ni-
Amorphous soft magnetic film 3 of B) having a thickness of about 20 μm
Was formed. The underlying nickel film is provided to prevent the crystal structure of the shaft 1 from adversely affecting the amorphous soft magnetic film 3 formed by electrolytic plating. The film of the unnecessary portion is masked before plating to prevent the film from adhering to the surface of the shaft 1.

The plating conditions are shown below. The electroless plating for forming the underlying nickel film is carried out at a bath temperature of 80 ° C., a dipping time of 15 minutes, and a top electroless plating bath N-47-
1 (manufactured by Okuno Seiyaku KK) was diluted 5 times with distilled water and used. The energization and electroless plating for forming the Fe-Ni-B amorphous soft magnetic film 3 are carried out at a bath temperature of 60 ° C., an energization time of 6 hours, a bath PH of 9.2, and a current density of 0.43 A / on the film forming surface of the shaft 1 surface. The composition of dm ² and the plating bath was as shown in Table 1.

[0017]

[Table 1]

The composition of the amorphous soft magnetic film 3 thus manufactured is iron, nickel, and boron in a weight ratio of 3.
It was 0, 68.5, 0.5. The contents of iron and nickel were measured by the fluorescent X-ray method, and the contents of boron were measured by the ICP method. Hereinafter, the magnetostrictive characteristic of the amorphous soft magnetic film 3 was examined using the detection circuit of FIG. In this detection circuit, coils 4 and 4 are wound around a pair of amorphous soft magnetic films 3 and 3 with a minute gap therebetween, and one end of each of the coils 4 and 4 is connected to a high power source V.
The voltage V ₀ between the emitters was detected by connecting to H and connecting the other ends to both collectors of a multivibrator which oscillates at a predetermined cycle. The voltage V ₀ between the emitters is proportional to the difference in reactance between the coils 4 and 4, that is, the difference in relative permeability between the amorphous soft magnetic films 3 and 3. Since the multivibrator type detection circuit itself of FIG. 1 is well known and is not an essential part of the present invention, its detailed description is omitted.

The thickness 70 produced by the plasma spraying method
0 μm amorphous soft magnetic film (40Fe-56Ni-
4Cr) and other conditions were the same, and Comparative Example product 1 was prepared. Further, iron, nickel, and silicon were added in a weight ratio of 17,
81 and 2, an amorphous soft magnetic film made of an amorphous ribbon (by a liquid quenching method) having a thickness of 20 μm was adhered to the shaft, and other conditions were the same, and comparative example product 2 was prepared.
Similarly, the voltage across the coil was detected. The results are shown in FIG.

From FIG. 3, it was found that the amorphous soft magnetic film 3 of the present example has an excellent output sensitivity as compared with the comparative products 1 and 2. Next, the linearity of the torque-output voltage characteristic of the torque sensor using the amorphous soft magnetic film 3 of the present embodiment was examined. In addition, as a comparative example product 3, a torque sensor using a crystalline soft magnetic film of the same thickness composed of 40Fe-56Ni-4Cr was also examined. The results are shown in FIG.

From FIG. 4, it was found that the soft magnetic film 3 of the present example has an excellent output sensitivity as compared with the comparative product 3. Hereinafter, the characteristics of the amorphous soft magnetic films of the above-described examples were examined by making test pieces. First, the direct current magnetic characteristics were examined. Therefore, an 80 × 20 × 2 (mm) aluminum plate is prepared as a base material, and 35 × 2 is provided on one side of the base material.
An exposure window was provided by 0 (mm), masking was performed thereafter, and the amorphous soft magnetic film 3 was plated by the same method as described above to prepare a test piece. Further, the amorphous soft magnetic film used as the comparative example product 2 was adhered to the aluminum plate to prepare a comparative example product 4, and its DC magnetic characteristics were also examined. Figure 5
The results are shown in.

From FIG. 5, it was found that the maximum magnetic flux density of the soft magnetic film of this example was large and it was effective for improving the output.
Next, the composition change of the amorphous soft magnetic film formed when the amount of Fecl ₂ added in the plating bath was changed was examined. The result is shown in FIG. From FIG. 6, it was found that even if the Fe / Ni molar ratio in the plating bath was increased, the Fe ratio in the amorphous soft magnetic film was saturated at 40 and several wt%. It was also found that the increase in the Fe / Ni molar ratio in the plating bath linearly decreases the boron ratio in the amorphous soft magnetic film. It is estimated that such a decrease in the boron ratio in the amorphous soft magnetic film is due to an increase in Fe, which has a relatively low affinity for boron.

Next, X-ray diffraction was performed on the amorphous soft magnetic film with the Fe ratio changed. The X-ray diffraction was performed using a fluorescent X-ray analyzer manufactured by Rigaku KK under the conditions of a sampling angle of 0.01 °, a scan speed of 1 ° / min, a tube voltage-tube current of 50 kV-150 mA. Was carried out without peeling from the shaft 1. The result is shown in FIG. As a result, it was confirmed that the distribution of the diffraction current of the amorphous soft magnetic film of the present example has a sufficiently flat characteristic as compared with the soft magnetic film of the comparative example 2 product and that it has an amorphous structure.

Further, the integrated width of the diffraction peak obtained by X-ray diffraction of the amorphous soft magnetic film of this embodiment is Sher.
The crystallite diameter was determined by substituting it into the Rerr equation. FIG. 8 shows the relationship between the Fe composition ratio and the crystallite diameter of the amorphous soft magnetic film. From FIG. 8, it was found that a good amorphous film can be obtained when the Fe composition ratio is 20 to 40 wt%. In this specification, a film having a crystallite diameter of 20 Å or less is an amorphous film.

Next, using the above plating bath, the change in composition of the amorphous soft magnetic film when the amount of applied current was changed was examined. As a result, when the applied current amount is 0.2 A / dm ² or less, the Fe ratio in the amorphous soft magnetic film coating is 40 w.
It could not be set to t% or more. Further, in order to secure a sufficient amount of boron (preferably 2 wt%) in the amorphous soft magnetic film for amorphization, the amount of Fe in the plating bath must be reduced, and as a result, plating is performed by energization. It is preferable to increase the Fe content in the amorphous soft magnetic film without increasing the Fe content in the bath.

As a result of the above, the following was found out. That is, the composition of the amorphous soft magnetic film can be adjusted by controlling the ratio of iron ions, nickel ions, and boron added to the plating bath, or by adjusting the energizing current. It is effective to conduct electricity by using the shaft as a cathode in order to reduce the iron content having a relatively weak affinity with.

It is considered that in the above-mentioned examples, boron is adsorbed at the crystal growth points and hinders the crystal growth, which causes iron-nickel as a magnetostrictive alloy to become amorphous. Therefore, it is sufficient to add boron within the range in which FeNi as a magnetostrictive metal can be made amorphous, and addition of more boron is not preferable because it decreases the iron content. This is also the case with cobalt, which has a relatively weak affinity with boron as with iron.

After all, the excellent magnetic characteristics as described above are
The amount of Fe in the film is 10 to 45 wt%, the amount of B is 1.0 to 5 wt%, the balance is Ni, and more preferably the amount of Fe in the film is 20.
-40 wt%, B content 1.5-3.5 wt%, balance N
It is preferably i.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a torque sensor using an amorphous soft magnetic film according to an embodiment of the present invention,

2 is an enlarged cross-sectional view of a cross section of the shaft of FIG. 1,

3 is a characteristic diagram showing frequency-output voltage characteristics of the soft magnetic film of FIG.

FIG. 4 is a characteristic diagram showing torque-output voltage characteristics of the soft magnetic film of FIG.

FIG. 5 is a characteristic diagram showing a DC magnetization characteristic of the amorphous soft magnetic film of Example 2.

6 is an X-ray diffraction diagram of the amorphous soft magnetic film of Example 2, FIG.

7 is a characteristic diagram showing the relationship between the Fe composition ratio, the crystallite size, and the coercive force of the amorphous soft magnetic film of Example 2, FIG.

FIG. 8 Fe / Ni of the amorphous soft magnetic film of Example 2
A characteristic diagram showing the relationship between the composition ratio and the Fe / Ni composition ratio in the plating bath,

[Explanation of symbols]

Reference numeral 1 is a shaft, and 3 is an amorphous soft magnetic film.

Claims (2)

[Claims] 1. An amorphous alloy containing a plurality of metals and a metalloid element on the surface of the base material by immersing the base material in an electroless plating bath containing a plurality of types of metal ions and a reducing agent containing a metalloid element. In the method for plating a film, a method for plating an amorphous alloy film, characterized in that the composition of the alloy film is adjusted by energizing the base material as a cathode. 2. The metal having a smaller affinity with the metalloid element is enriched by the energization.
Method for plating amorphous alloy film described