JPS6117212A - Joining of head groove part in magnetic head core - Google Patents

Abstract

PURPOSE:To obtain adequate hardness and to make the wear resistance of an adhesive agent equal to the wear resistance of a base metal by forming an adequate amt. of oxide in the adhesive agent. CONSTITUTION:The silver solder adhesive agnet prepd. by compounding alloy components of 1 or >=2 kinds selected from Mn, In, Sn, and Sb as the substitution type components with Ag-Cu-Zn-Cd silver solder in a manner as to satisfy a 1-10wt% range on the entire compsn. of the ashesive agent is embedded in a cavity part and is heated in a non-oxidative atmosphere to braze the cavity part. The brazed part is thereafter heated to 350-600 deg.C in an oxidative amt. to oxidize partly the silver solder components. The adequate range exists in the amt. of the solute elements to be compounded. The effect of improving the wear resistance is weakened at <1% and the deposited state of the oxide is made defective and the improving effect is unstable when the amt. exceeds 10%. The oxidation of the solute elements is not enough if the heating temp. is below 350 deg.C and the base components (solvent alloy) of the Ag-Cu-Zn-Cd alloy soften and the elements constituting the adhesive agent diffuse into the base metal when said temp. exceeds 600 deg.C. The deterioration in the recording and reproducing characteristics and further defective adhesion are then resulted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in the adhesion process in the manufacturing process of a magnetic head core, and more specifically, to improving the abrasion behavior of the base material portion and the adhesive portion in the head portion of the magnetic head core. This invention relates to an improved manufacturing method that can achieve uniformity.

[Prior Art] There is a strong desire to record information signals in a narrow track with high density in magnetic recording media for video or audio.In order to meet this demand, a medium using sendust alloy was developed. As a result, magnetic head cores with narrow gap widths and narrow track widths are being provided. Metallic magnetic materials such as sendust alloys have a characteristic of having a higher saturation magnetic flux density than conventional ferrite-based materials, and are attracting attention for this reason, but the manufacturing method established for ferrite-based materials remains unchanged. There are some aspects that cannot be applied to the production of heads made of metal magnetic materials, and for example, new methods have been developed that use silver solder for fixing block plates.

FIG. 4 is an explanatory diagram showing a conventional manufacturing procedure using a Sendust alloy (hereinafter simply referred to as Sendust in this specification) as a material. First, in step (A), a block plate 2 is cut out from a rectangular block 1 of sendust. Next, in step (B) (generally referred to as wafer processing), the block plate is divided into a groove processing block plate 2a and a non-groove processing block plate 2b, and a straight line is formed on the plate surface (especially one side surface) of the former 2a. A groove 3 is formed. The straight groove 3 is for forming a coil winding window W (see FIG. 4(H)), which will be described later, and is used as a groove machining block plate 2a.
It is common to form it parallel to the side edge S and to one side of the side edge S. The narrower bank with the straight groove 3 in between is called the front part 4, and the wider bank is called the back part 5.

In step (C), the surface of the front part 4 is subjected to non-adhesive processing (a process in which a non-magnetic substance is applied in a thin film form, also referred to as non-magnetic film adhesion processing) 4a, and a non-grooved The surface of the processing block plate 2b facing the front portion 4b [see FIG. 4(E)] is comb-cut in a direction perpendicular to the straight groove 3 to create a narrow track Ill! A T-shaped comb blade 6 is formed. In step (D), the track width T
A comb blade 7 is formed on the front part 4 so that the comb blades 7 are completely matched with each other.

In this specification, the four parts sandwiched between these comb blades 6 and 7 are referred to as head grooves 9. It will be referred to as lO.

Next, in step (E), two block plates 2a are formed.

2b are stacked so as to face each other, and both are joined. For joining, silver solder or the like is interposed between the surface of the back part 5 and the surface of the block 2b facing it, but the front part 4 is treated with non-adhesive treatment as described above (for example, a silica vapor deposited film). Since only the back part 5 is joined and the front part 4 is in opposing contact with each other. In the main (E) process, head grooves 9, 1
A cavity 11 is formed by the two facing each other. Then, in step (F), adhesive 8 is embedded in this cavity 11,
The contact surfaces of the comb blades 6 and 7 are reinforced from both sides. Furthermore ('G
) process, cutting and dividing [the cutting line is shown as a broken line in the diagram showing the (F) process, and each angle α is called an azimuth angle is performed, and finally, in the (H) process, the front part 4
The top surface of the side is polished into a spherical shape to produce a magnetic core 12.

Incidentally, FIG. 5 shows a plan view of the magnetic head core, and FIG. 6 shows an enlarged cross-sectional view taken along the line VI-Vl in FIG. , in FIG. 6, the tape runs in the direction penetrating the page. Figure 6 shows the state of wear due to sliding with the tape.The comb blade 6 is made of base material (sendust) and has high hardness, so the amount of wear is extremely small, while the adhesive 8 has silver solder. The amount of wear is extremely high due to its low hardness. As a result, polarization (depth D) as shown in FIG. 6 occurs, which has a significant influence on the output characteristics of the magnetic head core.

[Problems to be Solved by the Invention] In conventional magnetic head cores, there is a significant difference in strength between the base material and the adhesive that make up the sliding surface with the tape. ``The uneven wear described above appears in a relatively short period of time, and its depth D is also quite large.Therefore, as long as an adhesive with high hardness is selected, the uneven wear described above can be significantly suppressed. However, the current challenge is to develop an adhesive that satisfies all of these conditions, as it must not reduce adhesive strength or embedding workability. This invention was developed in view of the above circumstances, and the present invention was completed by discovering that all of the above conditions could be satisfied by using a silver solder with a special composition and by subjecting it to a special treatment.

[Means for solving the problem] An adhesive embedded part that exhibits abrasion resistance comparable to the base material without adversely affecting adhesive strength or embedding workability can be formed by the following method. We were able to. That is, in the present invention, AjH, Cu, Zn, and Cd are used to bond the head grooves by embedding an adhesive in the cavity formed by the opposing head grooves by placing the block plates with the head grooves facing each other. A g -Cu-Z n -Cd as the basic component
Rouni Kikan, M n , I n , S n and Sb
A silver solder adhesive comprising one or more alloy components selected from the following as substitutional components in an amount of 1 to 10% by weight (hereinafter simply referred to as %) of the total adhesive composition. The agent is embedded in the cavity, heated in a non-oxidizing atmosphere and waxed, and then heated to 350 to 600 in an oxidizing atmosphere.
The gist of this method is that it includes a step of oxidizing a part of the silver solder component by heating at .degree.

[Operation] The basic characteristic of the present invention is that the adhesive for embedding into the cavity formed by the opposing head grooves (hereinafter simply referred to as adhesive) can be improved. Therefore, to explain this adhesive, Ag-Cu-Zn-Cd silver solder containing Ag, Cu, Zn, and Cd is used as the base, and solute elements as described below are blended as substitutional elements. The abrasion resistance of the adhesive part is improved by adjusting the conditions of the bonding process.

First, the basic composition of the Ag-Cu-Zn-Cd based silver solder is not particularly limited in terms of composition as long as it can exhibit the properties as a brazing material. However, the most typical and widely used are JIS silver solder BAg-1°BAg-IA and BAg-2. The compositions of these alloys are shown in Table 1.

Table 1 (%) Therefore, the content of each of Ag, Cu, Zn, and Cd in the Ag-Cu-Zn-Cd silver solder of the present invention may be determined with reference to Table 1 above. In the explanation, BA
The case where the basic composition is silver solder g-1 will be described as a representative example. That is, the component composition of BAg-1 is A
g:44~46%, Cu:14~16%, Zn:14~
18%, Cd: 2.3-25%, so AgO,4
The average composition is 5° u0.152" 0.16 cdo, 24, which will hereinafter be representatively used to mean Ag-Cu-Zn-Cd based silver solder.

The adhesive of the present invention is one in which solute elements are substituted as described above, and if the solute element is Y and the blending ratio is X%, it can be expressed as follows.

(Ag O, 45Cu0.15ZnO, 16cd0.2
4〕(100-x)/] 0OYx/100 solute element Y
Examples include Mn, In, Sn, and Sb, and one or more of these may be selected and blended. The solute element Y is blended to convert the solute element into a highly hard oxide through oxidation treatment after brazing, thereby improving the wear resistance of the adhesive to a level comparable to that of the base material. Therefore, there is an appropriate range for the blending amount of solute element Y (if there are two or more types of solute element Y, their blending amounts), and if it is less than 1%, the amount of solute element oxide produced is small, so it is resistant to wear. The effect of improving sex becomes weaker. Therefore, a content of 1% or more is required, but the effect of improving wear resistance due to the production of oxides is stably exhibited at up to 10%.
If it exceeds 0%, the precipitation state of the oxide becomes poor and the improvement effect becomes unstable.

The adhesive having the above composition is filled into the cavity in step (F) of FIG. 4, where the oxidation step of step CB) of the brazing treatment of (A) is performed. The brazing process (A) is carried out according to standard brazing conditions, but the important point is that the solute elements, which are rich in non-oxidizing properties, are excessively oxidized at this stage and form complex oxides, which inhibit the performance of adhesive strength. The objective is to prevent any undesirable adverse effects from occurring, and for this purpose, it is required that the brazing process be performed in a non-oxidizing atmosphere (for example, a vacuum or an inert gas atmosphere). Under these conditions, not only the oxidation of the adhesive but also the oxidation of the sendust, which is the base material, is prevented, and a magnetic head core of good quality can be obtained. The temperature for brazing must naturally be above the melting point.

However, if the temperature exceeds 750° C., the elements constituting the adhesive will diffuse into the base material, changing the alloy composition of the sendust, causing a problem that the recording and reproducing characteristics of the magnetic head will deteriorate. Furthermore, it also causes poor adhesion. It is preferable that the heating time be 5 minutes or longer to completely melt and promote wetting with the base material. The longer the heating time, the better the wetting becomes and the better the adhesion effect becomes. However, this overgrowth reaches saturation in about 2 hours, and diffusion of alloy components is observed as in the case of high heating temperatures, so The upper limit should be . Regarding the formation of a non-oxidizing atmosphere, especially when performing brazing under vacuum, the degree of vacuum must be maintained at 10-' torr or less, otherwise the wetting gas may not be present sufficiently, resulting in poor adhesion. Caution is required.

When the brazing (A) is completed, the oxidation step (B) begins, and it is advantageous from a thermoeconomic standpoint to carry out the oxidation while the brazing temperature is decreasing. The oxidation process naturally needs to be carried out in an oxidizing atmosphere, and it is recommended that the oxygen content in the atmosphere at this time be in the range of 5 to 40% by volume, with the remaining gas being nitrogen, argon, etc. Inert gas power (desired. Heating temperature in the oxidation step is 35
Must be selected from the range of 0 to 600℃, 350℃
If it is less than that, the oxidation of the solute element will be insufficient. But 600
If the temperature exceeds ℃, the poisonous components of Ag-Cu-Zn-Cd alloy (
Solvent alloy) begins to soften, and defects similar to those caused when the brazing temperature in (A) becomes too high occur. The heating time is preferably 10 minutes to 2 hours; if it is less than 10 minutes, the oxidation of the solute element may be insufficient. On the other hand, regarding the upper limit, the above range is recommended because the oxidation reaction is sufficiently completed within 2 hours. If the time exceeds 3 hours, oxidation of the surface may progress excessively, resulting in coloration and a decrease in commercial value.

The operation of the present invention has been clarified above by explaining the essential configurations of the present invention and stating the preferred range.
The magnetic head core manufacturing process to which the adhesive of the present invention is applied is not limited to that shown in FIG. This method can be applied to all other methods of embedding adhesives in manufacturing processes that have been considered.

[Example] [Ago, 45cuO, 15ZnO, 16cd0.24
-' o, 960.04 (However, Y is Mn, In, Sn,
An adhesive (granular alloy) represented by one or more solute elements selected from Sb is shown in FIG. 4 (F).
It was embedded in the cavity 11 during the process. First l O-' t
Brazing treatment was performed at 700° C. for 30 minutes in a vacuum of orr or less, and then, during cooling, oxidation treatment was performed at 500° C. for 30 minutes (in air). As a result, the adhesive and the base material were firmly bonded, and fine oxides of solute elements were precipitated in the adhesive. When a coated metal tape running test was conducted using the magnetic head core obtained by performing all the steps shown in FIG. 4, the results shown in FIG. 1 were obtained. In addition, in FIG. 1, a product that did not undergo the oxidation process (marked with φ) is shown as a comparative example.

(Tape running test conditions) Coercive force Hc: 1450 oersted, ai density 145
Use tape coated with emu/g iron powder.

A commercially available video deck (1/2 inch, VH3 system) was used and run for 1000 hours at 40±2° C. and RH 70%.

As seen in Figure 1, uneven wear of 2.5 to 3 pm was observed in the case without solute elements added regardless of whether or not oxidation treatment was performed, whereas in the case of the case in which solute elements were added and oxidation treatment was performed. In the case of the adhesive, the amount of uneven wear was less than 1pm, and it can be seen that the wear resistance of the adhesive portion was significantly improved. In an example in which oxidation treatment was performed without adding a solute element, the example of the present invention did not show any effect, but the amount of uneven wear was considerably smaller than in an example in which no solute element was added and no oxidation treatment was performed. It is believed that this is because some of the Zn and Cd in the solvent elements were oxidized and precipitated, which gave the adhesive some high hardness and slightly contributed to improving the wear resistance.

Next, a running test was conducted while changing the type and amount of the solute element little by little while keeping the other conditions the same as in the case of FIG. 1. The results are as shown in FIG. 2, and uneven wear was common in cases where the solute element addition was less than 1% (0% in the figure) and in cases where it exceeded 10% (15% in the figure). In other words, with 0% adhesive, the adhesive was soft and uneven wear was likely to occur, while with 15% adhesive, there were too many oxides, so these were likely to peel off due to the sliding pressure of the running tape, causing uneven wear. Ta.

Next, similar tests were conducted with the solute element added at 0% or 4% and the heating temperature in the oxidation step varied (heating time was 30 minutes). Figure 3 is.

This shows the results below 350℃ (5 in the figure).
At temperatures above 750°C (600°C in the figure), the oxides of the solute elements become coarse and the solvent element Ag
As the oxidation of Cu and Cu progressed, the adhesive became brittle and uneven wear occurred.

[Effects of the Invention] Since the present invention is configured as described above, appropriate hardness is imparted by forming an appropriate amount of oxide in the adhesive, and as a result, the wear resistance of the adhesive is improved depending on the base material. It became. Therefore, even when used as a magnetic disk core for a long time, uneven wear of the adhesive portion is reduced, making it possible to exhibit good recording and reproducing characteristics over a long period of time.

[Brief explanation of drawings]

Figures 1 to 3 are graphs showing the degree of influence of each factor on uneven wear depth, Figure 4 is an explanatory diagram showing the manufacturing process of the magnetic head core, Figure 5 is a plan view of the magnetic head core, and Figure 6 is a graph showing the influence of each factor on uneven wear depth. 5 is an enlarged cross-sectional view taken along the line Vl-VI in FIG. 5. FIG.

Claims (1)

[Claims] Ag, Cu, Z
1 selected from Mn, In, Sn and Sb to Ag-Cu-Zn-Cd based silver solder having n and Cd as basic components.
One or more types or two or more types of alloy components in the total adhesive composition.
A silver solder adhesive compounded as a substituted component to satisfy the range of ~10% by weight is embedded in the cavity, heated and brazed in a non-oxidizing atmosphere, and then soldered in an oxidizing atmosphere. A method for joining a head groove in manufacturing a magnetic head core, the method comprising the step of oxidizing a part of a silver solder alloy component by heating at 350 to 600°C.