JPH03226590A - Formation of magnetic thin film by plating - Google Patents

Abstract

PURPOSE:To obtain an excellent soft magnetic thin film by specifying the current density at the pulse rise time, current density at the pulse suspension time and pulse duration time and further specifying the ratio of the pulse duration time to suspension time. CONSTITUTION:The magnetic thin film of an Fe-P-based alloy is formed by plating. In this case, a pulse power supply method is adopted. The current density IH at the pulse rise time in pulse power supply is controlled to 25mA/ cm<2=IH<=200mA/cm<2>. The current density IL at the pulse suspension time is adjusted to 0<=IL<=50mA/cm<2>. The pulse duration time tH is set at 10ms<=tH<=200 ms. The ratio of the pulse duration time tH to pulse suspension time tL is controlled to 0.1<=tH/tL<=10, and electrolysis is carried out. Consequently, a ferromagnetic thin film of an Fe-P-based alloy having a large area is obtained at a high film forming rate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for plating a magnetic thin film, and more specifically, to a method for plating a magnetic thin film, and more particularly, to a Fe-P system having excellent soft magnetism as a material for magnetic heads, magnetic shields, magnetic sensors, etc. This invention relates to a method for plating magnetic thin films of alloys.

Conventional plating methods for this type of magnetic thin film include the molten metal quenching method and the sputtering method. A magnetic thin film of an Fe--P alloy that is easily amorphized by the above-mentioned method exhibits excellent soft magnetism, with ferromagnetism and high saturation magnetization, but low coercive force. Therefore, it is viewed as a promising soft magnetic material for magnetic heads, magnetic shields, and the like.

In order to utilize such a magnetic thin film of an Fe--P alloy as the soft magnetic material, it is essential to establish a manufacturing technology that allows the magnetic thin film to be efficiently formed over a wide range of surfaces.

However, in the molten metal quenching method, it is technically difficult to rapidly cool the molten material of Fe or P, which is the raw material, so that the normal equilibrium state is not established, so it is difficult to obtain a magnetic thin film on a wide range of surfaces. I can't.

Furthermore, even in the sputtering method, the film formation rate is low and it is not possible to obtain a magnetic thin film over a wide area.

Therefore, the present inventor focused on an electroplating method that can obtain a large plated surface with both a large film forming rate and a large forming area. Conventional F
The electroplating method in the e-P system has been studied only for academic elucidation of the magnetic thin film structure formed and for its use as a base plating for chemical conversion treatment (Japan Institute of Metals Autumn Meeting -
Summary of the Lecture by Koku (1988, 111, "Electrodeposition of Fe-P Amorphous Alloys by Pulsed Current (213) J)". It is said that an amorphous magnetic thin film was obtained by electrolytic plating using pulsed energization.As a result of intensive study of the electroplating method for Fe-P alloys with reference to the above report, it was found that a non-crystalline magnetic thin film was obtained. We have identified the necessary and sufficient conditions to form a crystalline film,
Patent application 1986-31930 filed on December 26, 1988
We first proposed this method in issue 7.

Problems to be Solved by the Invention However, the conventional magnetic thin film plating method described above has the following problems.

■When using DC constant current energization as the energization method, Fe
The ionic molar concentration of ``Fe''] and the ionic molar concentration of P [Fe'']
[Fe2''']/[P] is 0.5 or more and 1.2
Limited to the following narrow range.

(2) In addition, with constant DC current, the upper limit of the current density that can be applied during electrolytic plating is about loomA, and there is a limit to the film formation rate.

■ In the case of the above report [electrification of Fe-P amorphous alloy @ (213) J by pulsed current, the pulse duration was fixed at 1 ms, so the pulse duration and amorphization The relationship between the two is not determined, and the magnetic properties of the obtained amorphous magnetic thin film are unknown.

(2) In the conventional example, the value of coercive force, which is a standard for measuring the soft magnetism of a magnetic thin film, is significantly larger than the value of coercive force exhibited by high-performance soft magnetic materials.

The present invention was invented in view of the above-mentioned problems, and
By using pulsed energization, Fe-
The object of the present invention is to provide a method for plating a magnetic thin film of a P-based alloy.

In order to achieve the above-mentioned object for solving the problems, the method for plating a magnetic thin film according to the present invention adopts a pulse energization method in a method for plating a magnetic thin film of an Fe-P alloy. The current A density IH at the pulse rise in pulse energization is 25 mA/c.
m2≦1. ≦200mA/cm2, and the current density during pulse rest is O≦1. ≦50 mA/cm2, the pulse duration IH is set to 10 ms≦tH≦200 ms, and the ratio tH/lL of the pulse duration tH to the pulse pause time t is set to 0.1≦tH/lL≦10. It is characterized by performing electrolytic plating.

FIGS. 1 to 4 show the results obtained by electrolytic plating using a pulse energization method in a method of plating magnetic thin films of Fe--P alloys.

In FIGS. 1 and 2, O indicates a crystalline state, (() indicates a partially amorphous state, and * indicates that a completely amorphous state was obtained.

Here, as a method for evaluating the crystallinity of the obtained magnetic thin film, X-ray diffraction was used to confirm its amorphization.

First, Figure 1 shows the setting conditions for pulse energization.
The ratio of pulse duration tH to pulse rest time tL tH/
It shows the correlation between each pulse duration tH and the current density at the pulse rise time and the precipitated phase when 1L is fixed at tH/1L=1. However, the current density at the pulse rise ■.

is variable depending on the value of the current density IL at the time of pulse rest, but this time it was fixed to IL=O. As is clear from this figure, the current density at the rise of the pulse is 1. is 25mA
/cm2≦1. The magnetic thin film was completely amorphous when the pulse duration tH was 10 ms≦tH≦200 ms at ≦150 mA/cm2.

Moreover, FIG. 2 shows the pulse duration IH as t. =100m
It shows the correlation between each t H/t L and the current density at the rise of the pulse and the precipitated phase when fixed at s. However, the current density at the time of pulse rise is 1. Although it is variable depending on the value of the current density during pulse rest, this time it was fixed at IL=0. As is clear from this figure,
Current density at pulse rise■8 is 25mA/cm”≦
t o / t L is 0 when IN≦150mA/cm2
．． The magnetic thin film was completely amorphous in the range of 1≦to/tL≦10.

Next, FIG. 3 shows the setting conditions for pulse energization, t
H/1L = tH/1L = t, o, current density during pulsed current I) Each pulse duration when l is fixed at IH = roomA/cm", and ion mole I of Fe"
Ratio of l[Fe2″″] to P molar concentration [P] [Fe”]
It shows the correlation between /[P] and the precipitated phase. As is clear from this figure, the pulse duration tH is 10ms≦t
When H≦200ms, the shaded area in the figure, that is, the plating bath composition [Fe2''] / where an amorphous magnetic thin film was obtained.
The range of [P] was significantly expanded.

In addition, FIG. 4 shows that the pulse duration to is tH=room
s, the current density IH at the pulse rise = 10
Each tH/lL and [F
e"] / [P] and the precipitated phase. As is clear from this figure, to/lL is 0.1≦t
When H/lL≦10, the shaded area in the figure, that is, the range of plating bath composition [Fe'']/[P] in which a non-quality magnetic thin film was obtained, was significantly expanded.

As described above, by employing the pulse energization method under the above conditions, the magnetic thin film was made amorphous over a wider range of plating bath compositions than in the case of the DC constant current energization method.

As mentioned above, in the method of plating magnetic thin films of Fe-P alloys, a pulse energization method is adopted, and the current density IH at the pulse rise in the pulse energization is set to 25 mA/c.
m2≦1. ≦200mA/cm2, and the current density during pulse rest is 0≦IL≦50mA/cm2,
Set the pulse duration tH to 10'ms≦1.5200ms, and set tH/lL to 0.1≦tH/lL≦
By performing electrolytic plating with a setting of
A magnetic thin film of a based alloy is formed on a metal substrate.

! EXAMPLES Example 1 Below, examples and comparative examples of the magnetic thin film plating method according to the present invention will be described.

First, ferrous sulfate (Fe504.7H
Sodium hypophosphite (Na
Add HzPOz ・Hail and write in Tables 1 and 2 below.
A pure copper cold-rolled plate (width 40 mm, length 160
One end (width 40 mm, length 40 mm) of this pure copper cold-rolled plate was prepared as a plating area, and the remaining part was covered with insulating tape, and this was used as a cathode. In this case, a platinum plate was placed on the pure copper cold-rolled plate and the copper plate between the gaps, and the edge of the platinum plate (width 40 mm, length 40 mm) was left as the plating area, and the rest was covered with insulating tape. Then, the above two electrodes were immersed in an electrolytic solution, and while the electrolytic solution was stirred at 500 to 600 revolutions per minute by a magnetic rotor, a current pattern (rectangular waveform) as shown in Fig. 5 was applied. ) Electrolysis was carried out by applying a direct current pulse having the following characteristics.The conditions for this pulsed current application were in accordance with the setting conditions listed in Tables 1 and 2 below.

(Left below) In other words, each of the above setting conditions is as described in Tables 1 and 2, and 1 to 11 in Table 1 are comparative examples where plating was performed under conditions outside the scope of the present invention. Then, the current density at the pulse rise is set to I s < 25 mA/cm2 or I s > 150 mA/cm2, the current density at the pulse rest is set to 0, and the pulse duration t is set to t, < 10 ms. Or t H > 200ms
and tH/lL is 1. /1. <01 or t, /l
L>10, and [Fe”] / [P] is O1≦
The test was carried out within the range of [F e ''] / [P]≦100. In the table, * marks specifically indicate conditions outside the scope of the present invention.

Items 12 to 24 in Table 2 were plated under conditions within the scope of the present invention.

In order to investigate the characteristics of the 6R thin film of Fe-P alloy obtained by the above method, the coercive force was measured using a simple holding camera, and the crystallinity of the magnetic thin film was determined by X-ray diffraction. I checked.

In each table, those with a coercive force of 0.50e or less are marked with a circle, indicating that a good magnetic thin film was obtained, and those with a coercive force of greater than 0.50e are marked with a circle, indicating that the desired soft magnetism was not obtained. × is marked.

Examining the results of this example and comparative examples from Tables 1 and 2, it is found that in the comparative examples shown in Table 1, amorphous was only partially formed in the obtained magnetic thin film. be. As a result, the coercive force became extremely high, and a desired magnetic thin film could not be obtained.

On the other hand, in this example shown in Table 2, the obtained magnetic thin film was completely amorphous, so the coercive force was small and good soft magnetism was exhibited.

As described above, by the magnetic thin film plating method according to this example, it is possible to obtain a magnetic thin film of a ferromagnetic Fe-P alloy that has a large deposition rate and a large formation area, and furthermore, this magnetic thin film has a low coercive force and is excellent. It exhibited soft magnetism.

Although ferrous sulfate fFeS047H201 was used as the Fe2 + source in the electrolytic solution in the above example, the present invention is not limited to this, and ferrous chloride fFe1
26H201, ferrous nitrate fFe (NO-12・6H
There is no problem in using a compound containing divalent iron ions such as 201 instead.

Although sodium hypophosphite (NaH2P02H20) was used as a P source in the above example, it is not limited to this, and phosphoric acid fhOs·nHzo;
n is an integer) phosphate (M, PO2, MH2PO4, M2
P04: M is a metal that forms a salt with phosphoric acid), phosphorous acid (H2PH03, HFO2, H2PJzOsl, phosphite (MaPH (h, MPO□M2PJaOs:
M is a metal that forms a salt with phosphoric acid), hypophosphorous acid (HP
There is no problem in using one type or a mixture of two or more of H20°) or hypophosphite (MPH20-; M is a metal that forms a salt with phosphoric acid).

However, in the case of using a mixture of two or more types, the 1 degree phosphorus used in the present invention refers to the total phosphorus concentration.

2! As is clear from the above explanation, according to the method for plating a magnetic thin film according to the present invention, a pulse energization method is adopted in the method for plating a magnetic thin film of Fe-P alloy, and in the pulse energization, Current density IH at pulse rise is 25
mA/cm2≦1. ≦200mA/cm2, and the current density IL during pulse rest is 0≦1, ≦50mA/cm”
and the pulse duration tH is 10ms≦tH≦20.
Set to 0ms, and set the ratio tH/j+ of pulse duration t14 to pulse rest time 1L to 0.1≦tH/t.
By performing electrolytic plating with L≦10, it is possible to obtain a magnetic thin film of a ferromagnetic Fe-P alloy with a large deposition rate and large formation area, and furthermore, this magnetic thin film has an excellent low coercive force. It exhibited soft magnetism.

[Brief explanation of drawings]

FIG. 1 shows the pulse duration t. Figure 2 is a graph showing the relationship between the current density □ at the pulse rise and the precipitated phase. A graph showing the relationship, Figure 3, shows the relationship between pulse duration tH and [Fe”] / [
A graph showing the relationship between P] and the precipitated phase, Figure 4 is t H/
A graph showing the relationship between t L, [Fe'']/[P] and the precipitated phase, and FIG. 5 is a waveform diagram showing the current pattern of the DC pulse used in this example. Current density...Current density at pulse rest...Pulse duration...Pulse rest time

Claims (1)

[Claims] In the method of plating magnetic thin films of Fe-P alloys, a pulse energization method is adopted, and the current density I_H at the rise of the pulse in the pulse energization is set to 25 mA/cm^2≦I_
H≦200mA/cm^2, current density I_L during pulse rest is 0≦I_L≦50mA/cm^2, and pulse duration t_H is 10ms≦t_H≦200ms.
and set the ratio t_H/t_L of pulse duration t_H to pulse rest time t_L to 0.1≦t_H/t.
A method for plating a magnetic thin film, characterized in that electrolytic plating is performed by setting _L≦10.