JP2010059512A - Ni-Fe-P-BASED ELECTROLESS-PLATED FILM, AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an Ni-Fe-P-based electroless-plated film which can form an oxidation prevention film of several nanometers on the surface side, by controlling the concentration of sodium potassium tartrate in particular, and to provide a method for producing the same. <P>SOLUTION: The Ni-Fe-P-based electroless-plated film 1 has an oxidation prevention film 2 with a film thickness of several nanometers containing COOH, FeO<SB>2</SB>, FeO and NiO formed on its surface 1a side. Thereby, the electroless-plated film can control oxidation occurring on the plated film, can reduce a change of magnetic properties with elapsed time, and can acquire the stable magnetic properties. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a NiFeP-based electroless plating film capable of forming an anti-oxidation film of several nm on the surface side and a method for manufacturing the same.

  As described in the following patent document, it is known to use potassium sodium tartrate as a complexing agent for electroplating. In particular, Ni-based plating films have generally used potassium sodium tartrate as a complexing agent.

  The complexing agent is used for the purpose of not causing precipitation in the plating solution, and for incorporating an appropriate amount of Ni or Fe into the plating film, and has not been used for any other purpose.

Conventionally, in order to form an antioxidant film on the surface of the NiFeP-based electroless plating film, after forming the NiFeP-based electroless plating film, an antioxidant film is formed again on the surface of the NiFeP-based electroless plating film. It was necessary.
JP 2002-57031 A JP 2006-185692 A

  Therefore, the present invention is for solving the above-described conventional problems, and in particular, a NiFeP-based electroless plating capable of forming a several nm antioxidant film on the surface side by adjusting the concentration of sodium potassium tartrate. It aims at providing a film | membrane and its manufacturing method.

The present invention relates to a NiFeP-based electroless plating film,
In the depth direction from the surface side, COOH, is characterized in that the FeO _2, FeO and several nm thickness antioxidant film containing NiO is formed. Thereby, the oxidation in a plating film can be suppressed, the time-dependent change of a magnetic characteristic can be made small, and the stable magnetic characteristic can be acquired.

The present invention also relates to a method for producing a NiFeP-based electroless plating film,
The plating bath contains Ni ions, Fe ions and phosphite ions or hypophosphite ions and 1.06 mol / L to 1.7 mol / L of sodium potassium tartrate. Thereby, an antioxidant film having a thickness of several nanometers including COOH, FeO ₂ , FeO, and NiO can be appropriately and easily formed in the depth direction from the surface side of the plating film.

  Moreover, in this invention, it is preferable to set Fe ion to a value smaller than the boundary line of 0.0001 mol / L or more and Fe ion concentration = 0.005 / sodium potassium tartrate concentration. Thereby, sodium potassium tartrate can be dissolved appropriately, and precipitation in the plating solution can be suppressed.

According to the present invention, by adjusting the concentration of sodium potassium tartrate, an antioxidant film having a thickness of several nm containing COOH, FeO ₂ , FeO and NiO is formed in the depth direction from the surface side of the NiFeP electroless plating film. I can do it. Therefore, the oxidation in the plating film can be suppressed, the change over time in the magnetic characteristics can be reduced, and stable magnetic characteristics can be obtained.

  FIG. 1 is a schematic view of the NiFeP electroless plating film of this embodiment. The illustrated X direction indicates the width direction, and the illustrated Z direction indicates the height direction (film thickness direction).

  The NiFeP electroless plating film 1 shown in FIG. 1 is formed, for example, within a range where the Ni concentration is 83 to 87 wt%, the Fe concentration is 6 to 9 wt%, and the P concentration is 4 to 10 wt%.

  As shown in FIG. 1, an antioxidant film 2 having a film thickness H1 of several nm is formed on the surface 1a side. The anti-oxidation film 2 is formed not only in the form of several nm in the depth direction from the surface 1a but also in the depth direction from the position entering the depth direction to some extent (several tens of millimeters) from the surface 1a. Also includes form.

The antioxidant film 2 is formed including COOH, FeO ₂ , FeO and NiO. COOH, FeO ₂ , FeO, and NiO are all contained in the antioxidant film 2 more than in regions other than the antioxidant film 2. Specifically, in the antioxidant film 2, the outermost surface (around 0 to 4 nm in the depth direction from the surface) and the inside (depth from the surface to the depth) by time-of-flight secondary ion mass spectrometry (TOF-SIMS). The strength ratio (internal strength / outermost surface strength) is 0.16 or less for COO (CHO ₂ ), 0.34 for FeO ₂ , 0.9 or less for FeO, and 1 for NiO. .15 or less.

  The antioxidant film 2 is not composed of only the above four components. The antioxidant film 2 is formed on the surface side which is the last plating growth of the NiFeP electroless plating film 1. The antioxidant film 2 includes simple substances such as Ni, Fe, and P.

  The thickness H1 of the antioxidant film 2 is preferably 0.1 nm to 5 nm, and more preferably 4 nm or less.

As described above, in the present embodiment, the antioxidant film 2 having a thickness of several nanometers including COOH, FeO ₂ , FeO, and NiO is formed in the depth direction from the surface 1a side of the NiFeP-based electroless plating film 1. Is formed. Therefore, the oxidation in the plating film can be suppressed, the change with time of the magnetic characteristics can be reduced, and the stable magnetic characteristics can be maintained. According to experiments described later, it is known that the change with time of the coercive force Hc can be reduced. Further, the film thickness H1 of the antioxidant film 2 is about several nanometers, and does not deteriorate the magnetic characteristics.

  The plating bath in the NiFeP-based electroless plating film 1 of the present embodiment includes Ni ions, Fe ions and phosphite ions or hypophosphite ions, and 1.06 mol / L to 1.7 mol / L sodium potassium tartrate. Including.

  Here, in the plating bath, Fe ions are contained, for example, as a Mole salt (iron (II) sulfate. Heptahydrate). Ni ions are included, for example, as nickel sulfate hexahydrate.

  In the present embodiment, Fe ions are set to a value smaller than 0.0001 mol / L and smaller than the boundary line of Fe ion concentration = 0.005 / sodium potassium tartrate concentration. Here, since the sodium potassium tartrate concentration is within the range of 1.06 mol / L to 1.7 mol / L as described above, the upper limit value of the Fe ion concentration can be obtained from the above formula.

  In the present embodiment, the Ni ions contain a concentration that is 0.03 mol / L added to the Fe ion concentration, and include phosphite ions or hypophosphite ions in the range of 0.06 mol / L to 0.18 mol / L. Is preferred. In addition, it is preferable that 0.2 to 0.50 mol / L of ammonium sulfate is contained.

  Next, as plating conditions, the pH of the plating bath is 7.0 to 10.0, and the temperature of the plating bath is 60 to 90 ° C.

  Then, the substrate is immersed in a plating bath, and a NiFeP electroless plating film 1 having a thickness of about 2 to 3 μm is formed on the surface of the substrate by plating.

In this embodiment, as described above, the sodium potassium tartrate concentration is defined as 1.06 mol / L to 1.7 mol / L. When the sodium potassium tartrate concentration is less than 1.06 mol / L, the antioxidant film 2 having a thickness of several nm containing COOH, FeO ₂ , FeO and NiO cannot be effectively formed on the surface 1a side. Moreover, 1.7 mol / L is the upper limit of dissolution of sodium potassium tartrate.

In the present embodiment, by defining the sodium potassium tartrate concentration as 1.06 mol / L to 1.7 mol / L, COOH, FeO ₂ , in the depth direction from the surface 1a side of the NiFeP-based electroless plating film 1 The antioxidant film 2 having a thickness of several nm containing FeO and NiO can be formed appropriately and easily. That is, in this embodiment, the antioxidant film 2 can be formed on the surface side which is the last plating growth of the NiFeP-based electroless plating film 1. Therefore, it is not necessary to form the antioxidant film 2 again after the NiFeP-based electroless plating film 1 is formed.

  Further, as described above, in this embodiment, the Fe ions are set to 0.0001 mol / L or more and smaller than the boundary line of Fe ion concentration = 0.005 / sodium potassium tartrate concentration. Thereby, sodium potassium tartrate can be dissolved appropriately, and precipitation in the plating solution can be suppressed.

A NiFeP-based electroless plating film was formed by electroless plating using the following plating bath.
(1) Example (plating bath composition)
Iron (II) sulfate heptahydrate 0.001 (mol / L)
Nickel sulfate hexahydrate 0.029 (mol / L)
Sodium hypophosphite 0.120 (mol / L)
Sodium potassium tartrate 1.06 (mol / L)
Ammonium sulfate 0.35 (mol / L)
(Bath conditions)
Bath temperature 80 ° C
pH 8.0
(2) Comparative example (plating bath composition)
Iron (II) sulfate heptahydrate 0.001 (mol / L)
Nickel sulfate hexahydrate 0.029 (mol / L)
Sodium hypophosphite 0.120 (mol / L)
Sodium potassium tartrate 0.27 (mol / L)
Ammonium sulfate 0.35 (mol / L)
(Bath conditions)
Bath temperature 80 ° C
pH 7.8

  Using the plating baths of the above-described examples and comparative examples, each of the NiFeP-based electroless plating films was electrolessly plated, and then analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). It was. For the time-of-flight secondary ion mass spectrometer, TOF-SIMS V manufactured by ION-TOF was used.

Bi ⁺ (1 pA, 25 keV) was used for the excitation ION beam, and Cs ⁺ (500 eV) was used for the sputter-etched ions, and negatively charged secondary ions were detected.

  The depth profile in FIG. 2 (a) is the measurement result of the NiFeP-based electroless plating film (Example) obtained by electroless plating by adding 1.06 mol / L of sodium potassium tartrate, and the depth profile in FIG. 2 (b) is tartaric acid. It is a measurement result of the NiFeP type electroless-plating film (Example) which added sodium potassium 0.27 mol / L and electrolessly plated.

  FIG. 3A is a three-dimensional schematic diagram showing the state of each component based on the depth profile of FIG. 2A, and shows that there are many components in bright portions. FIG. 3B is a three-dimensional schematic diagram showing the state of each component based on the depth profile of FIG.

  Table 1 below shows the intensity ratio of each component in FIGS. 3 (a) and 3 (b). 0 to 50 sec is near 0 to 4 nm in the depth direction from the surface, and 150 to 200 sec is near 13 to 17 nm in the depth direction from the surface.

  Further, after 50 days, the depth profiles of the NiFeP-based electroless plating films of Examples and Comparative Examples were measured again. FIG. 3 (c) shows the state of each component in a three-dimensional schematic diagram based on the depth profile of the example after 50 days. Based on the depth profile of the comparative example after 50 days, each component FIG. 3D shows this state in a three-dimensional schematic diagram.

As shown in FIG. 2A, FIG. 3A, and Table 1, in the example, a large amount of COOH, FeO ₂ , FeO, and NiO is included in the range of about 4 nm in the film depth direction from the vicinity of the surface. all right. Intensity ratio between outermost surface (near 0 to 4 nm from surface to depth) and inside (near 13 to 17 nm from surface to depth) by depth profile by time-of-flight secondary ion mass spectrometry (TOF-SIMS) (intensity of internal strength / outermost surface) of the CHO ₂ 0.16 or less, the FeO ₂ 0.34, the FeO 0.9 or less, was found to be a NiO in 1.15 or less.

Next, as shown in FIG. 2 (b), FIG. 3 (b), and Table 1, in the comparative example, COOH, FeO ₂ , FeO, and NiO are not concentrated in the vicinity of the surface. In the vicinity of the surface, it has been found that there is no antioxidant film having a film thickness of several nm containing COOH, FeO ₂ , FeO and NiO. In the comparative example, the outermost surface (near 0 to 4 nm from the surface to the depth direction) and the inside (near 13 to 17 nm from the surface to the depth direction) by the depth profile by time-of-flight secondary ion mass spectrometry (TOF-SIMS) intensity ratio (internal strength / intensity of the outermost surface) in the CHO ₂ 0.18 with, the FeO ₂ 0.51, the FeO 1.35, has a 1.79 in NiO, as compared with examples It turned out to be extremely high.

  3 (c) and FIG. 3 (a) in the example are not so much changed, and in the example, the oxidation into the film does not progress so much even after 50 days. I understood. On the other hand, in FIG. 3D of the comparative example showing 50 days later, it was found that the oxidation into the film further progressed compared to FIG. 3B.

  Next, FIG. 4 and FIG. 5 are graphs showing the change in intensity ratio according to the depth profile of each component in Examples and Comparative Examples after 50 days as a percentage. The intensity ratio of each component was measured at a depth position of about 15 nm from the surface. The rate of change in the strength ratio of each component was indicated by [(strength ratio after 50 days−strength ratio immediately after plating formation) / (strength ratio immediately after plating formation)]. That is, in the graphs of FIGS. 4 and 5, the closer to 0%, the smaller the change in the intensity ratio and the less the oxidation.

  As shown in FIGS. 4 and 5, it was found that the change in the strength ratio of the components was larger in the comparative example than in the example.

  Next, as shown in Tables 2 and 3 below, a plurality of NiFeP-based electroless plating films formed by electroless plating from plating baths having different sodium potassium tartrate addition amounts were prepared, and each NiFeP-based electroless plating was performed. The coercivity and saturation magnetization of the film were measured.

  As shown in Tables 2 and 3, the amount of sodium potassium tartrate added was 0.27 (mol / L) and 1.06 (mol / L).

  The plating bath composition and conditions other than the sodium potassium tartrate addition amount were set to be the same as in the above experiment.

  In the experiment, the coercive force and saturation magnetization of each sample were measured both immediately after plating and after 50 days.

  As shown in Tables 2 and 3, in the sample to which 0.27 (mol / L) of sodium potassium tartrate was added, the decrease in the coercive force after 50 days was larger than that of the other samples and the oxidation progressed. I found out.

Finally, the concentration range of sodium potassium tartrate and the Fe ion concentration range are defined.
FIG. 6 (a) is a graph showing the solubility limits of tartaric acid, sodium tartrate, and sodium potassium tartrate. As shown to Fig.6 (a), the solubility limit of sodium potassium tartrate was 1.7 (mol / L).

  Subsequently, it was found that precipitation may occur depending on the concentration of sodium potassium tartrate and Fe ions. In order not to cause precipitation, it was found that the sodium potassium tartrate concentration and the Fe ion concentration must be defined as follows.

  First, it was found that when [sodium potassium tartrate concentration] / [Fe ion concentration] was 15 or less, precipitation of iron hydroxide was observed, and it was necessary to make it larger than 15. The relational expression [potassium sodium tartrate concentration] / [Fe ion concentration]> 15 is shown in FIG. 6 (b) (1).

  Next, it was found that when [potassium sodium tartrate concentration] · [Fe ion concentration] is 0.005 or more, precipitation of iron tartrate was observed, and it was necessary to make it smaller than 0.005. The relational expression [potassium sodium tartrate concentration] · [Fe ion concentration] <0.005 is shown in FIG. 6 (b) (2).

  The range surrounded by the relational expressions (1) and (2) in FIG. 6B is shown in a dark color. When this result is combined with the solubility limit of the sodium potassium tartrate concentration in FIG. 6 (a) and the experimental result of the sodium potassium tartrate concentration described above, the preferred sodium potassium tartrate concentration range and Fe ion concentration range are as shown in FIG. 6 (c). It was found to be within the range shown in white.

  That is, sodium potassium tartrate is included in the range of 1.06 mol / L to 1.7 mol / L, and Fe ions are 0.0001 mol / L or more, Fe ion concentration = 0.005 / sodium potassium tartrate concentration ( It was found that it is preferable to set a value smaller than the boundary line of the equation (2), which is a modified equation.

Schematic diagram of the NiFeP electroless plating film of this embodiment, The depth profile of (a) is a measurement result of a NiFeP-based electroless plating film (Example) obtained by electroless plating by adding 1.06 mol / L of sodium potassium tartrate, and the depth profile of (b) is 0 for sodium potassium tartrate. Measurement result of NiFeP-based electroless plating film (Example) electrolessly plated with addition of 27 mol / L, (A) is a three-dimensional schematic diagram showing the state of each component based on the depth profile of FIG. 2 (a) (Example, immediately after plating), and (b) is based on the depth profile of FIG. 2 (b). The three-dimensional schematic diagram showing the state of each component (comparative example, immediately after plating), (c) is a three-dimensional schematic diagram showing the state of each component based on the depth profile of the example after 50 days, (d) Is a three-dimensional schematic diagram showing the state of each component based on the depth profile of the comparative example after 50 days, A graph showing the change in the intensity ratio of each component in Examples and Comparative Examples after 50 days, A graph showing the change in the intensity ratio of each component in Examples and Comparative Examples after 50 days, A graph for defining the concentration range of sodium potassium tartrate and the Fe ion concentration range;

Explanation of symbols

1 NiFeP-based electroless plating film 1a Surface 2 Antioxidation film

Claims (3)

In the NiFeP-based electroless plating film,
An NiFeP-based electroless plating film, wherein an antioxidant film having a thickness of several nanometers containing COOH, FeO ₂ , FeO, and NiO is formed in the depth direction from the surface side. In the manufacturing method of the NiFeP-based electroless plating film,
NiFeP-based electroless characterized in that the plating bath contains Ni ions, Fe ions and phosphite ions or hypophosphite ions and 1.06 mol / L to 1.7 mol / L of sodium potassium tartrate. A method for producing a plating film.   The method for producing a NiFeP-based electroless plating film according to claim 2, wherein Fe ions are set to a value that is 0.0001 mol / L or more and is smaller than a boundary line of Fe ion concentration = 0.005 / sodium potassium tartrate concentration.

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