Method of manufacturing flying magnetic heads

A method of manufacturing a flying magnetic head of composite type using a magnetic thin film layer as a head core. The flying magnetic head comprises a slider, an I core bar bonded via a high-melting-point bonding glass layer to one end face of the slider and a C core bonded via a high-melting-point bonding glass layer serving as a gap spacer to the I core bar. The I core bar and C core have respective magnetic thin film layers, which are aligned to each other and mated with an ABS of the slider. I core bar is formed at a position corresponding to a wiring groove of the C core with a window groove. Such flying magnetic heads having a smooth ABS can be readily and massively manufactured.

BACKGROUND OF THE INVENTION 
Field of the Invention 
This invention relates to techniques for flying magnetic heads used with 
magnetic disk drives and, more particularly, to a method of manufacturing 
flying magnetic heads of a composite type using a thin-film-laminated core 
as a head core (or a head chip). 
Recently, composite type flying magnetic heads, which use as a head core a 
thin-film-laminated core obtained by laminating on a substrate a magnetic 
thin film comprising an Fe-Si-Al alloy (Sendust), an amorphous magnetic 
material, an iron nitride type alloy, etc., have attracting attention 
because they can be used for magnetic disk drives and the like, permit 
high density recording and permit track width reduction. 
FIG. 13 shows a flying magnetic head commonly called a composite type, 
which has been proposed earlier by the present applicant as Japanese 
Patent Application No. 84441/1991. This flying magnetic head comprises a 
head 1 and a slider 2 and, although not shown, is connected to an actuator 
of an associated apparatus via a leaf spring support mechanism. 
This flying magnetic head uses a bonding glass m having a high melting 
point in lieu of a low-melting molding glass which has hitherto been used 
for bonding the head core 1 to the slider 2. Thus, it can greatly reduce 
the exposed area of the glass layer m on an air-bearing-surface 
(hereinafter referred to simply as "ABS") 4 and extremely improve the CSS 
(contact start characteristic, thus extremely improving the reliability as 
a whole. 
However, even the composite type flying magnetic heads using such a 
thin-film-laminated core are required to provide improved performance. 
Particularly, it is desired to increase the number of turns of a winding 
200 provided in the head core 1 from 40 turns at present to turns, for 
instance. 
To this end, it is necessary to expand a wiring groove 20 formed in a C 
core 18. 
To meet this aim, the inventors produced a head core 1 with expanded wiring 
groove 20 by forming a transversal window groove 19A in an I bar 19, as 
shown by phantom lines. In this case, however, the corresponding end 
portion of the head core 1, bonded to the slider 2, popped during the 
processing of the ABSs such as a processing to form edge grooves 100 and a 
top center groove 101 and also a processing to form inclined surfaces 102 
and 103. It was thus impossible to obtain smooth ABSs. This seems to be 
due to a reduction of the mechanical strength of the head 1 itself and 
hencereduction of the resistance of the ABS surfaces againstgrinding, 
caused by the formation of the transversal window groove 19A in the I bar 
19. 
In order to provide a composite type flying magnetic head, which permits 
increase of the turns number of the head core winding to enhance 
performance without reducing the mechanical strength of the head core, 
facilitates the processing of the ABS, permits a smooth ABS to be obtained 
and uses a thin-film-laminated core as the head core, the inventors 
produced a flying magnetic head of composite type, as shown in FIG. 1, 
which comprises a slider having an ABS, an I core bar having a magnetic 
thin film layer, one end face of the I core bar being bonded to the entire 
area of one end face of the slider such that the magnetic thin film layer 
of the I core is mated with the ABS, and a C core having a magnetic thin 
film layer, the C core being bonded to the other end face of the I core 
bar such that the magnetic thin film lamyer of the C core bar is mated 
with the magnetic thin film layer of the I core bar, the I core bar being 
formed at a position thereof corresponding to a wiring groove with an 
inclined window groove having a predetermined inclination angle .theta.. 
SUMMARY OF THE INVENTION 
The present invention relates to a method of manufacturing such flying 
magnetic head. 
According to the invention, the above flying magnetic head is manufactured 
by a method, which comprises: 
(a) forming a magnetic thin film layer on each of a plurality of 
substrates; 
(b) bonding together said plurality of substrates each provided with said 
magnetic thin film layer with intervening high-melting-point laminate 
glass layers to form a magnetic thin film lamination; 
(c) slicing said magnetic thin film lamination in the direction of the 
thickness of said lamination to obtain a plurality of core plates; 
(d) grooving one of the principal surfaces of some of said core plates in a 
direction perpendicular to said magnetic thin film layer to form wiring 
grooves and apex glass molding grooves, thus obtaining C core plates 
formed with said wiring grooves and said apex glass molding grooves at 
predetermined positions; 
(e) slicing other ones of said core plates in a direction parallel to said 
magnetic thin film layers to obtain I core bars; 
(f) forming each of said I core bars with a given number of window grooves; 
(g) depositing at least a high-melting-point bonding glass layer on the 
surface of each said C core plate formed with said wiring grooves and on 
the surface of each said I core bar formed with said window grooves; 
(h) overlapping the bonding glass layer formation surfaces of each of a 
given number of said I core bars and each said C core plate, overlapping a 
dummy plate with a high-melting-point bonding glass layer formed thereon 
and the other surface of said I core bars and bonding together said I core 
bars, said C core plate and said dummy plate with intervening bonding 
glass layers to form a magnetic head block; 
(i) grooving said magnetic head block on the side of said C core plate to 
form C cores having a predetermined head core thickness; 
(j) subsequently, slicing said magnetic head block in a direction parallel 
to said C cores to obtain a given number of magnetic head bars; 
(k) forming each said magnetic head bar with edge grooves and a center 
groove, thus forming ABSs and then slicing the resultant magnetic head bar 
to obtain a given number of flying magnetic heads; 
(l) obliquely chamfering front and rear portions of said ABSs of each said 
separated flying magnetic head to form inclined surfaces; and 
(m) providing a winding on the C core of each said flying magnetic head. 
The softening point of the high-melting-point laminate glass is set to 
650.degree. to 800.degree. C. The softening point of the 
high-melting-point bonding glass is set to 550.degree. to 650.degree. C. 
The substrate and dummy plate are formed of a non-magnetic material or 
ferrite. The magnetic thin film layer is formed of an Fe-Si-Al alloy, an 
amorphous magnetic material or an iron nitride type alloy.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Now, the method of manufacturing flying magnetic heads according to the 
invention will be described in detail in conjunction with an embodiment 
thereof with reference to the drawings. 
FIG. 1 shows a flying magnetic head of a composite type. In this flying 
magnetic head, a head core (or head chip) 1 and a slider 2 are bonded 
together, and this slider 2 with the head core is connected to an actuator 
of a magnetic disk drive via a leaf spring mechanism (not shown). 
More specifically, this flying magnetic head, like the flying magnetic head 
disclosed in Japanese Patent Application No. 84441/1991 filed by the 
present applicant and described before in connection with FIG. 13, 
comprises, in addition to the slider 2, an I core bar 19 bonded by a 
high-melting-point bonding glass layer m to the entire area of one end 
face of the slider 2 and a C core 18 bonded via a gap spacer 21 such as 
the high-melting-point bonding glass layer m to the I core bar 19. The I 
core bar 19 and C core 18 have respective magnetic thin films 14, which 
are aligned to each other and mated with the ABS 4 of the slider 2. 
Further, the I core bar 19 has an inclined window groove 22 formed in a 
position corresponding to wiring groove 20. The inclination angle .theta. 
of the inclined window groove 22 may be selected as desired. Together with 
the wiring groove 20 of the C core 18, the inclined window groove 22 can 
provide a winding space. 
Now, the method of manufacturing the flying magnetic head according to the 
invention will be described. 
First, a method of manufacturing a thin-film-laminated head core used as 
the head core 1 by laminating magnetic thin films on a substrate will be 
described. For the magnetic thin film, Fe-Si-Al alloy magnetic materials, 
amorphous magnetic materials, iron nitride type alloys and so forth may be 
used. According to the preferred embodiment of this invention, an Fe-Si-Al 
alloy magnetic material is used. 
In this method, a non-magnetic substrate 11 of a ceramic or the like is 
prepared (FIG. 2(A)). On the substrate 11 an Fe-Si-Al alloy film 12 is 
deposited to a thickness of 1 to 20 .mu.m by a spattering process. Then, 
on the Fe-Si-Al alloy film 12 a non-magnetic insulating film 13 is 
deposited to a thickness of 0.03 to 0.5 .mu.m by a spaterring process 
(FIG. 2(B)). The non-magnetic film 13 may be formed of SiO.sub.2, Al.sub.2 
O.sub.3, etc. 
The above sequence of operations is repeated to laminate necessary numbers 
of the Fi-Si-Al alloy and non-magnetic insulating films 12 and 13, thus 
forming a magnetic alloy thin film layer 14 having a thickness t on the 
substrate 11 as shown in (FIG. 2(C)). 
Then, on the magnetic thin film layer 14 a high-melting-point laminate 
glass 15 having a softening point of 650.degree. C. or above, preferably 
650.degree. to 800.degree. C., is formed to a thickness of 0.05 to 1.0 
.mu.m by a spattering process or the like (FIG. 2(D)). The laminate glass 
15 may be formed suitably by using an SiO.sub.2 -Al.sub.2 O.sub.3 
-Na.sub.2 O type glass or an SiO.sub.2 -B.sub.2 O.sub.3 -Na.sub.2 O type 
glass. 
Subsequently, as shown in FIG. 3, a plurality of substrates 11 each with 
the magnetic thin film layer 14 formed in the above way are stacked 
together with a top dummy plate 16, and then pressed together in a jig or 
the like under heating. Thus, the individual stack members are bonded 
together by the laminate glass layers 15 to obtain a magnetic thin film 
lamination 30 (FIG. 3(A)). The dummy plate 16 is of the same material as 
the substrate 11. The lamination 30 is sliced in the thickness direction 
of lamination as shown by phantom lines in FIG. 3(A) to obtain core plates 
40 for manufacturing C cores 18 and I core bars 19 (FIG. 3(B)). 
Some of the core plates 40 thus obtained are then each formed on one side 
and at predetermined positions thereof with wiring grooves 20 and grooves 
for receiving apex glass moldings ma, these grooves extending 
perpendicular to the magnetic thin film layer 14, thus obtaining C core 
plates 18'. 
Other core plates 40 are each cut in a direction parallel to the magnetic 
thin film layer 14 as shown by phantom lines in FIG. 3(B) to obtain 
eventual I core bars 19 (FIG. 3(C)). Each I core bar 19 is then formed 
with inclined window grooves 22 having a predetermined inclination angle 
.theta. by incline-grooving or spot facing, as shown in FIG. 5. The pitch 
P.sub.c of wiring grooves 20 in the C core plate 18' and the pitch P.sub.I 
of the inclined window grooves 22 in the I core bar 19 are made equal. The 
width W.sub.c of the wiring groove 20 and the width W.sub.I of the 
inclined window groove 22 are not limited but usually made equal. The 
depths h.sub.c and h.sub.I of the grooves 20 and 22 are appropriately 
selected as desired. 
After the formation of the wiring grooves and inclined window grooves, the 
surface 18'a of the C core plate 18' formed with the wiring grooves 20 and 
the surface 19a of the I core bar 19 formed with the inclined window 
grooves 22 are polished. Then, on the polished surfaces 18'a and 19a a 
non-magnetic gap material, for instance SiO.sub.2, is formed by 
spattering, and then the bonding glass layer m is formed by means of the 
spattering process. Where no gap material is provided, the bonding glass 
layer m itself also serves as a gap spacer 21. The bonding glass layer m 
suitably comprises a high-melting glass with a melting point of 
550.degree. C. or above, preferably 550.degree. to 650.degree. C., for 
instance, an SiO.sub.2 -Al.sub.2 O.sub.3 -Na.sub.2 O type glass or an 
SiO.sub.2 -B.sub.2 O.sub.3 -Na.sub.2 O type glass. 
Then, as shown in FIG. 6, each C core plate 18' and a corresponding number 
of the I core bars 19 are overlapped with their bonding glass layer 
surfaces 18'a and 19a face to face by aligning the wiring grooves 20 of 
the C core plate 18' and inclined window grooves 22 of the I core bars 19 
and also aligning the magnetic thin film layers 14, i.e., by carrying out 
track alignment. Then, as shown in FIG. 7, a dummy plate 25 is overlapped 
over the other surface of the I core bars 19. Of course at this time, the 
bonding glass layer m is formed by means of spattering on the but surface 
of the I core bars 19 and/or the dummy plate 25. The thickness of the 
bonding glass layer m for the bonding of the I core bars 19 and dummy 
plate 25, may be set to be substantially equal to the gap to be obtained, 
for instance 0.1 to 0.7 .mu.m. The dummy plate 25 comprises a ceramic or 
like non-magnetic material and has a rectangular sectional profile. It 
constitutes eventual slider 2. The bonding glass layer m, as noted above, 
suitably comprises a high-melting-point glass with a melting point of 
550.degree. C. or above, preferably 550.degree. to 650.degree. C., for 
instance an SiO.sub.2 -Al.sub.2 O.sub.3 -Na.sub.2 O type glass or an 
SiO.sub.2 -B.sub.2 O.sub.3 -Na.sub.2 O type glass. 
The C core plate 18', I core bars 19 and dummy plate 25 thus overlapped 
over one another, are then bonded to one another via the bonding glass 
layer m in a jig or the like under heating and pressing, thus obtaining a 
magnetic head block 50. 
It is to be appreciated that by the manufacturing method according to the 
invention the bonding of the C core plate 18', I core bars 19 and dummy 
plate 25, i.e., the formation of the gap 21 in the head core 1 and the 
bonding of the head core 1 and slider 2, can be attained simultaneously 
using the high-melting-point bonding glass layer m. FIG. 8 shows the 
magnetic head block 50 obtained in the above way with the dummy plate 25 
down. 
Then, as shown in FIG. 9, the magnetic head block 50 has its side of the C 
core plate 18' formed with grooves to form eventual C cores 18 with a head 
core thickness T. The magnetic head block 50 is then cut to obtain 
magnetic head bars 60 as shown in FIG. 10. 
Each magnetic head bar 60 is then subjected to the processing of the ABS 4 
such as the formation of the edge and center grooves 100 and 101, as shown 
in FIG. 11, and then cut apart to obtain eventual flying magnetic heads 
each comprising the head core 1 and the slider 2, as shown in FIG. 12. 
Regarding the processing of the ABS, referring to FIG. 1, usually the edge 
grooves 100 each have a width of 50 to 100 .mu.m and a depth from the ABS 
of 20 .mu.m or above. The width 4.sub.w of the ABS is usually 200 to 500 
.mu.m. Each separated flying magnetic head then has front and rear corners 
of its ABS 4 chamfered obliquely to form inclined surfaces 102 and 103 as 
its inlet and outlet end portions. 
It has been found that with the above method of manufacture according to 
the invention the ABS 4 can be processed without any problem of the 
popping of the end portion of the head core 1, that is, the ABS can be 
processed very smoothly and readily to obtain smooth ABS. 
Further, while in the above embodiment window grooves were shown to be 
inclined, it is possible to apply not-inclined window grooves. 
Furthermore, while in the above embodiment the substrate 11 and slider 2 of 
the head core 11 were shown to be made of a ceramic or like non-magnetic 
material, it is possible to use ferrite or various other materials as 
well; for instance, ferrite may be used for both the substrate 11 and 
slider 2 of the head core 1. Further, while in the above description an 
Fe-Si-Al alloy magnetic material was used for the magnetic thin film layer 
14 of the head core 1, it is possible to use an amorphous magnetic 
material or an iron nitride type alloy as well as noted before. 
Further, while in the above embodiment the C core 18 of the head core 1 was 
provided in correspondence to a single ABS, it is possible to provide a C 
core in correspondence to each of the two ABSs 4 as well. 
The invention will be described in further detail in connection with an 
example. 
EXAMPLE 1 
As the non-magnetic substrate 11 was used a non-magnetic ceramic substrate 
principally composed of CoO-NiO, and the magnetic thin film layer 14 was 
formed on the substrate 11 by depositing suitable numbers of Fe-Si-Al 
alloy films 12 and non-magnetic insulating films 13 alternately by the 
spattering process in the manner as described before in connection with 
FIG. 2. In this example, SiO.sub.2 was used for the non-magnetic 
insulating films 13, and the thickness of the magnetic thin film layer 14 
was set to 10 .mu.m as the track width. 
Subsequently, on the magnetic thin film layer 14 a laminate glass film 15 
having a high melting point (with a softening point of 700.degree. C.) was 
deposited to a thickness of 0.25 .mu.m by spattering. The 
high-melting-point laminate glass film (with a softenig point of 
700.degree. C.) was also deposited to a thickness of 0.25 .mu.m by 
spattering on the dummy plate 16 of the same material as the substrate 15. 
For the laminate glass 15 was used an SiO.sub.2 -Al.sub.2 O.sub.3 
-Na.sub.2 O type glass. 
Then, eight substrates 11 each with the magnetic thin film lamination 14 
were stacked together with the dummy plate 16 at the top such that the 
laminate glass 15 of the dummy plate 16 is face to face with the magnetic 
thin film layer 14 on the uppermost substrate 11, and the stack was 
pressed in a thermal press at 730.degree. C. to obtain the magnetic thin 
film lamination 30. 
The magnetic thin film lamination 30 was then sliced in the thickness 
direction of stacking to obtain the core plates 40. The opposite surfaces 
of each of these core plates 40 were then mirror surface finished. 
One of the core plates 40 thus obtained then was formed on one side thereof 
with glass molding grooves extending perpendicular to the magnetic thin 
film layer 14, and apex glass moldings ma were fusion bonded along the 
glass molding grooves. Then, portions of the core plate, in which the apex 
glass moldings were provided, were formed with the wiring grooves 20. In 
this way, the C core plate 18' with the wiring grooves 20 and apex glass 
moldings ma formed at predetermined positions was obtained. 
Meanwhile, another core plate 40 was sliced in a direction parallel to the 
magnetic thin film layer 14 to obtain the eventual I core bars 19. Each of 
these I core bars 19 was then formed with the inclined window grooves 22 
having an inclination angle (.theta.) of 30.degree. by spot facing. 
In this example, the pitch P.sub.c of the wiring grooves 20 in the C core 
plate 18' and the pitch P.sub.I of the inclined grooves 22 of the I core 
bar 19 were set to 0.994 mm, the width W.sub.c and W.sub.I of the wiring 
grooves 20 and inclined grooves 22, respectively, were set to 0.35 mm, and 
the depths h.sub.c and h.sub.I of the wiring grooves 20 and inclined 
grooves 22, respectively, were set 0.27 and 0.57 mm, respectively. 
After the formation of the wiring grooves and inclined grooves, the surface 
18'a of the C core plate 18' with the wiring grooves 20 formed therein 
and the two surfaces of the I core bar 19 were polished. Then, on the 
polished surfaces, i.e., on the surface 18'a of the C core plate 18' with 
the wiring grooves 20 formed therein and the two surfaces of the I core 
bar 19, a bonding glass layer m having a high melting point (i.e., a 
softening point of 580.degree. C.) was deposited by spattering. The 
thickness of the bonding glass layer m was set to 0.15 .mu.m. For the 
bonding glass m was used an SiO.sub.2 -Al.sub.2 O.sub.3 -Na.sub.2 O type 
glass. 
Then, a predetermined number of the I core bars 19 were overlapped one by 
one over the C core plate 18' by effecting track alignment, i.e., by 
aligning the inclined grooves 22 of the I core bars 19 to the wiring 
grooves 20 of the C core plate 18' and also aligning the magnetic thin 
film layers 14, and then the dummy plate 25 is overlapped over the other 
surface of the I core bars 19. The overlapped I core bars 19, dummy plate 
25 and C core plate 18' were then fusion bonded together in a jig at 
600.degree. C. and by application of a pressure, thus obtaining the 
magnetic head block 50. 
Subsequently, the head blocks 50 each were grooved on the side of the C 
core plate 18' to form the C core 18 having a head core thickness (T) of 
0.2 mm. Then, the magnetic head block 50 was sliced to obtain magnetic 
head bars 60. 
Subsequently, the magnetic head bar 60 had its opposite surfaces ground and 
then formed with the edge grooves 100 and center groove 101, thus forming 
the ABS 4 with a width (4.sub.w) of 0.34 mm. Then, it was cut at positions 
of 0.25 mm from the center of the magnetic thin film layer (track) 14, 
thus obtaining flying magnetic heads each comprising the head core 1 and 
slider 2 and having a head width and thickness of 2.24 and 0.61 mm, 
respectively. 
Then, front and rear corners of the ABSs 4 were chamfered obliquely to form 
the inclined surfaces 102 and 103, then the ABSs 4 and inclined surfaces 
102 and 103 were finish polished, and the winding is provided on the C 
core 18. In this example, a 60-turn winding could be attained without any 
problem. 
As has been described in the foregoing, with the manufacturing method 
according to the invention a flying magnetic head having a smooth ABS can 
be readily and massively manufactured.