Method of manufacturing a magnetic head

Two soft magnetic core halves of amorphous metal are connected together via a non-magnetic gap and the core halves are supported bilaterally by two core supports. The core supports have a connection member at the gap area and at the short-circuit area of the head block thus constructed on both sides of the head gap. The parts of the head are welded by means of the connection members to form a mechanically stable unit.

BACKGROUND OF THE INVENTION 
The invention relates to a method of manufacturing a magnetic head in which 
two soft magnetic core halves of amorphous metal are connected together 
via a non-magnetic gap. The core halves which are bilaterally supported by 
two core supports, are combined to a head block. The core supports have a 
connection member at the gap area and at the short-circuit area, whilst 
coil turns are wound around at least one core half and in which 
furthermore a head block is split up into two connected half blocks. 
In consumer electronics video magnetic tape recorders magnetic heads having 
small trackwidths and extremely small gap lengths are used in large piece 
numbers. This results in the volume of such a head being very small. The 
main problem of manufacturing such a small magnetic head in large series 
is that the annular core provided with a gap is to be given a sufficient 
mechanical stability and that the magnetic head is to have a wear 
resistant long lifetime. 
Methods of manufacturing a magnetic head with a small trackwidth are known 
whose mechanical stability is achieved by a supporting member provided 
unilaterally or bilaterally on the annular core. The parts are joined by 
means of bonding layers of low-melting point glass or of silicon resin. 
A drawback of this method is that due to the small bonding faces and due to 
the partly insufficient bonding of the materials the stability of the 
connection between the annular core (core halves) and the supporting 
members supporting these halves is inadequate. 
SUMMARY OF THE INVENTION 
A magnetic head having amorphous metallic core halves with a small 
trackwidth and an extremely small gap length is provided. All head parts 
(core halves and core support) are mechanically connected together in a 
stable manner by means of a sealed connection of the separate parts and 
the stable connection is suitable for a method of manufacturing magnetic 
heads in large piece numbers, which can be carried out automatically.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows the way in which two connected half blocks 1a, 1b are formed. 
Firstly each block half is laminated, that is to say, an amorphous metal 
foil is each time provided as a core half 2a, 2b between each two core 
supports 3a, 3b. The core supports 3a and 3b are each provided with 
connection members 4a, 4b both at the gap area 5 and at the short-circuit 
area 6. When stacking the single components 2a, 3a in block 1a and 2b, 3b 
in block 1b it is additionally possible to provide them with a glass 
interface in advance which, by the effect of pressure and temperature, 
additionally hardens the half block. In any case, however, the connection 
members 4a and 4b, which are preferably a low melting point glass, connect 
the components in an adequate manner. According to a further step the 
surfaces of each half block provided as gap faces are ground, lapped and 
polished to an optimum surface smoothness. Each second half block 1b is 
provided with a channel as a free space for the coil turns. Subsequently 
the non-magnetic gap material 12 is provided in known manner, for example 
by vapour deposition. The processed surfaces of the two half blocks 1a, 1b 
are then pressed together in a device and the half blocks are welded 
together both at the gap area 5 and at the short-circuit area 6 by means 
of a laser weld 7 at each area of a single head block to be separated at a 
later stage. The overall block which is thus bonded mechanically is 
finally separated by means of sawing along the indicated lines c into 
single head blocks 8 (FIG. 3). 
FIG. 2 shows a detail of FIG. 1 on a larger scale, namely a laser weld spot 
7 at the gap area between the two half blocks 1a and 1b. Two weld spots 7 
are formed in the front surfaces for each gap, one on either side thereof 
as shown. 
FIG. 3 shows a single head block 8 separated from the overall block, whose 
parts are connected together by means of laser weld 9 on the two surface 
sides at the gap area 5 and at the short-circuit area 6 via the connection 
members 4a and 4b. The separate parts of the block 8 are now mechanically 
bonded in such a rigid manner that it is possible, by means of processing 
the face on the side of the gap area and the short-circuit area, to 
substantially remove the welding spots provided on the overall block. The 
tape contact face 10 is simultaneously given the ultimate arched form. The 
parts on the separate head block 8 are again bonded at the areas where 
critical heating of the amorphous metal 2a, 2b is avoided. Due to the 
removal of the frontal faces in the gap and short-circuit areas it is 
achieved, in addition to the formation of the tape contact face with the 
desired gap height, that the welding-affected areas on the overall block 
in the amorphous metal of the core halves are removed. Finally the single 
head block 8 is provided with coil turns 11 as shown in FIG. 4.