Note: Descriptions are shown in the official language in which they were submitted.
~47~6~L
"Magnetic head using a magne-tic field-sensitive element and method of
manufacturing same".
The invention relates generally to a magnetic head for use in a
magnetic reproductlon device. The magnetic head comprises in particular a
substrate on which a magnetic field-sensitive element is provided in the form
of a thin film, the necessary leads being present to provide electric con-
nections to external circuits.
In the manufacture of magnetic heads of the annular core type
which so far has been the most usual type, the front face of the head is
ground away, while the height of the gap is measured optically so as to de-
termine the quantity of the material of the head which has still to be ground
away or removed. The more time-consuming and hence expensive character
makes such a method unfit for use in the series production of magnetic heads
comprising magnetic field-sensitive elements, for example, Hall elements or
magnetoresistance elements, in the form of thin films.
In the prior art series production process for heads of the above-
described type, a number of magnetic field-sensitive elements in the form of
thin films are provided, for example, by vapour deposition in vacuo, on sub-
strates of a uniform size which form part of the ultimate head construction;
electric leads for the elements are formed on each substrate by vapour depos-
iting a metal thereon; by adhering the substrates each on a glass plate with
the side having a thin film, the fundamental construction of a head is ef-
fected. When the method conventionally used in manufacturing heads of the
annular core type were used, the front face of the head, that is to say the
surface which is destined to be coupled to a magnetic recording medium, must
then be ground away until a desired uniform height of the magnetic field-
sensitive elements has been achieved. Due to the very small dimensions of
the elements, the grinding away down to the required height is a very accur-
ate and time-consuming job, while in the case of larger numbers of elements
on a substrate it is very difficult to ma~e the height of the elements
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~147~L6~
uniform. Consequently, heads manufactured in this manner often have un-
equal characteristics relative to each other, that is to say, the reprod-
ucibility factor of the known method of manufacturing large numbers of uni-
form heads of the present type is low.
It is the object of the invention to provide a new and improved
magnetic head, as well as a method of manufacturing came, which eliminates
the drawbacks of the prior art. The invention provides in particular a head
construction in which the grinding away of the front face of the head is no
longer necessary.
For that purpose, the magnetic head according to the invention is
characterized in that the magnetic field-sensitive element is provided on a
side wall of a groove extending in a surface of the substrate.
The invention also relates to a method of manufacturing 1 magnetic
head having a magnetic field-sensitive element. Said method is characterized
in that a groove having a defined shape is provided in a surface of a sub-
strate, that an auxiliary layer is vapour-deposited at a first angle with the
substrate on the surface of the substrate on either side of the groove and on
a wall of the groove, that a layer of magnetic field-sensitive material is
vapour-deposited at a second angle with the substrate on the auxiliary layer
on either side of the groove and on the wall of the groove present opposite
to the said wall, that the auxiliary layer with the magnetic field-sensitive
material present thereon is etched away, and that the remaining layer of mag-
netic field-sensitive material is connected to electric leads.
The invention will be described in greater detail, by way of example,
with reference to the drawing.
Fig. 1 is a perspective view of a first embodiment of a substrate
for a magnetic head according to the invention.
Figs. 2, 3 and 4 are cross-sectional views taken on the line A-B
of the substrate shown in Fig. 1 during three successive stages of the method
according to the invention.
Fig. 5 is a plan view of a second embodiment of a substrate for a
magnetic head according to the invention.
In Fig. 1, a groove 2 having a readily defined shape is provided
in a substrate 1. When a detrition-resistant substrate is required, sapphire
or a carbide may be chosen for that purpose and sputter etching is a suitable
method of providing the groove 2. If on the contrary silicon is used as a
substrate, a groove whose walls extend normal to the surface can be manufactur-
ed by means of anisotropic etching. Said normal position is to be preferred
because the magnetic field-sensitive element to be provided will in that case
also be normal to the surface.
In Fig. 2, an auxiliary layer 3 having a thickness between 500 and
lo,ooo R of, for example, Al or Cu is vapour-deposited on the surface of the
substrate 1 and on the wall 5 of the groove 2 at an angle ~ with the substrate
1. Due to the shadow effect of sald vapour deposition method, an auxiliary
layer is produced only in the places denoted in the Figure.
In Fig. 3 a layer 4 having a thickness of 1000 R of a magnetic
field-sensitive material, for example, a material having magnetoresistive
properties (like Ni-Fe~, is vapour-deposited on the wall 6 o~ the groove 2
at an angle ~ with the substrate surface.
In Fig. ~, the auxiliary layer 3 with the part of the layer ~ pre-
sent thereon is etched away, the layer 4 being broken off at the area of the
surface so that only the part of the layer ~ on the wall 6 remains. The
height _ hereof is dependent only on the vapour deposition angle and on the
place of the edge 7 and can be adjusted accurately. Dimensions of h of, for
example, 5 microns t 0.5 can be reali~ed in this manner. Grinding away of
the substrate so as to adjust the height is hence not necessary in the
method according to the invention.
As has been already stated above, the material of the auxiliary
layer 3 may be, for example, Al or Gu. Generally, said layer should consist
of a material which can be e-tched away in the presence of a layer ~ which
7~
may not be attacked. In the case in which the layer 4 consists of NiFe, Al
is a very suitable material for the auxiliary layer 3.
In Fig. 5, a groove 8 in the form of an open loop has been etched
in the substrate 9. In the above-described manner, a layer of magnetoresis-
tive material is provided on the outer wall 11 at least in the part of the
groove 8 on the right-hand side of the line G-H, via vapour-deposition at a
first angle of an auxiliary layer, vapour-deposition at a second angle of a
layer of magnetoresistive material, and etching away the auxiliary layer in-
cluding the layer of magnetoresistive material present thereon. A layer of
lacquer 10 (shaded area) is then provided which covers the part of the groove
between C and D which corresponds to the groove 2 in Fig. 1. The remaining
part of the groove 8 is then filled up to the surface of the substrate with
a conductive mater:ial, for example Au. Due to the oblique transition of the
groove at C and D, said conductive material readily contacts the magnetoresis-
tive material present on the wall 11. At the points E and F the conductive
material can be connected to an external circuit by means of "beam leads"
or a "through hole plating" technique.
If desired it is also possible to fill the groove between C and D
with, for example, SiO for further p-rotection of the magnetoresistive layer
provided on the wall 11 thereof. An extra step for building the magneto-
resistive element in, as is necessary in the prior art, is not necessary in
this case.
