Metal working – Method of mechanical manufacture – Electrical device making
Patent
1984-04-10
1987-06-09
Czaja, Donald E.
Metal working
Method of mechanical manufacture
Electrical device making
29416, 51281R, 65 36, 65 42, 65 591, 65 602, 156154, 156235, 156632, 156634, 156636, 156645, 156656, 156657, 2041922, 20419223, 360122, G11B 5127
Patent
active
046709720
DESCRIPTION:
BRIEF SUMMARY
TECHNOLOGICAL FIELD
The present invention relates to a method for making magnetic heads.
TECHNOLOGICAL BACKGROUND
In recent years advances in high coercive metalized tape have stimulated research into magnetic heads which comprises high magnetic density core material. Promising materials for such magnetic cores can be found in Sendust (Tradename) and amorphous alloys. However, the method currently used in forming magnetic gaps in ferrite cores cannot readily be applied to the formation of magnetic gaps in such high magnetic density core materials. More specifically, in the current method use is made of glass which is sandwiched between ferrite core halves and bonded thereto by fusion at elevated temperatures. Advantages reside in the fact that in the fusion process the glass partially diffuses into the core material and increases the bonding strength and that a suitable glass material can be easily found to match the thermal expansion coefficient of the core material used. However, Sendust and amorphous alloys have a considerably low bonding strength to glass, and in addition the thermal expansion coefficient of Sendust is typically 170.times.10.sup.-7 which is considerably greater than that of glass that ranges between 50.times.10.sup.-7 and 120.times.10.sup.-7. Mismatch in thermal expansion coefficient presents a serious problem. The low bonding strength is considered to arise from the fact that glass is less capable of diffusing into such materials than it is with ferrite materials. In the case of amorphous alloys, the difficulty is that their crystalization temperature, which is around 500.degree. C., requires that glass fusion be effected at temperatures lower than this crystalization temperature. Otherwise, amorphous alloys would lose their required magnetic properties. Thus, fusion bonding is more difficult to achieve in the case of amorphous alloys than in the case of Sendust. Although the use of resinous materials can be considered as a gap filling material, their pronounced characteristic in thermal expansion and contraction renders them unsuitable for such applications where the gap length is required to meet the tolerance range of .+-.0.1 micrometers.
SUMMARY OF THE INVENTION
The present invention is therefore to eliminate the above-mentioned problems and has for its object the provision of a method whereby a magnetic gap is formed with a higher degree of precision.
According to the present invention, a magnetic gap is formed by the use of a sputtering method and supplementarily with the use of a bonding method in which glass or resin is employed as a strengthening material. The method of the present invention ensures high precision and ease with which magnetic heads are fabricated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1a-1h and 2a-2c are perspective views illustrating a method for making a magnetic head according to the present invention; and
FIGS. 3a-3f and 4a-4e are perspective views illustrating another method of the present invention which is an improvement over the method of FIGS. 1 and 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates the steps 1a to 1h of making a magnetic head according to an embodiment of the present invention.
A substrate 1 is cut off along a central portion 2, forming substrate halves 3 and 7. On the surface of a substrate half 3 a magnetic layer 4 is formed by a sputtering method as shown in FIG. 1. An end face 5 is polished to a mirror finish and a nonmagnetic gap filling layer 6 is sputtered thereon. The substrate half, thus obtained, is aligned end-to-end with the other substrate half 7 as shown in FIG. 1d and bonded together. This bonding can be effectively made by cutting out a portion 8 as indicated by a broken line in the step d and pouring fused low-melting-point glass into the cut-out portion 8. On the upper surface of the recombined subtrate 9 is a magnetic layer 10 which is similar in material to layer 4 and which is formed by the sputtering technique, as illustrated in FIG. 1e. Since the subtrate halves 3 and 7 are magnetica
REFERENCES:
patent: 3629519 (1971-12-01), Hanak
Abstract of Japanese Document 55-73913 (Takehara), Jun. 4, 1980, Technical Library-Foreign Patent Publications.
Bokan Thomas
Czaja Donald E.
Matsushita Electric - Industrial Co., Ltd.
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