Method of bonding a magnetic head element to a supporting beam

A connecting pad of a magnetic head element is bonded to a signal conductor of a supporting beam. As a result of the bonding, the magnetic head element is mechanically coupled to the supporting beam and the connecting pad is electrically connected to the signal conductor. Also an auxiliary pad of the magnetic head element is bonded to the signal conductor. This bonding improves the mechanical coupling strength of the magnetic head element to the supporting beam. When the magnetic head element is to be bonded to the supporting beam, one of the pads is bonded to the signal conductor, and thereafter the other pad is bonded to the signal conductor. During the process of the latter bonding, a groove which is previously disposed in the signal conductor blocks heat given for the bonding from being transmitted to the former bonding portion in which bonding has been already completed, thereby preventing the bonding of the former bonding portion from being broken.

TECHNICAL FIELD 
The invention relates to a method of bonding a magnetic head element to a 
supporting beam in a contact-type magnetic head during a process of 
producing the magnetic head. 
BACKGROUND ART 
A contact-type thin film magnetic head is used in the manner shown in FIG. 
4A. Referring to FIG. 4A, 1 designates a magnetic disk, and 2 designates a 
supporting arm which supports a magnetic head and has a basal portion 2a 
connected to an actuator for moving the head. The reference numeral 3 
designates the contact-type thin film magnetic head which is attached to 
the tip portion of the supporting arm 2, 4 designates a supporting beam in 
a magnetic head 3 and the beam is elastic and has a basal portion 4a 
attached to the supporting arm 2, 5 designates a contact-type thin film 
magnetic head element which is disposed at the tip portion of the 
supporting beam 4, and 6 designates a contact tip of the head element 5. 
The contact face 6a of the contact tip is caused to contact with the 
surface 1a of the magnetic disk 1 by the elasticity of the supporting beam 
4 and performs recording and reproducing on the magnetic disk 1. For 
example, the magnetic head element 5 has a sectional structure shown in 
FIG. 4B. The reference numeral 7 designates the body made of an insulating 
material such as aluminum oxide, 8 designates a pole for performing 
recording and reproducing on a magnetic disk, 9 designates a return yoke, 
10 designates a magnetic core, 11 designates a yoke, 12 designates a coil, 
and 13 designates a connecting pad for performing mechanical and 
electrical connections to the supporting beam 4. The connecting pad is 
mechanically fixed to the body 7 and electrically connected to the coil 12 
(for example, Japanese Published Unexamined Patent Application No. 
6-274829). 
When the magnetic head 3 is to be produced, the magnetic head element 5 is 
bonded to the supporting beam 4. The bonding is conducted by soldering the 
connecting pad 13 of the magnetic head element 5 to a signal conductor 
disposed in the supporting beam 4 (for example, Japanese Published 
Unexamined Patent Application No. 6-150250). 
In the above-mentioned method, the mechanical coupling of the magnetic head 
element 5 to the supporting beam 4, and the electrical connection of the 
connecting pad 13 of the magnetic head element 5 to the signal conductor 
of the supporting beam 4 are conducted at one time, and hence the working 
efficiency is excellent. 
In the bonding by means of only the connecting pad, however, there is a 
limit in bonding force. To comply with this, it is desired that the 
mechanical coupling strength of the magnetic head element to the 
supporting beam is enhanced with the result that the stability of the 
state of attaching the magnetic head element to the supporting beam is 
further improved. 
SUMMARY OF THE INVENTION 
The method of bonding a magnetic head element to a supporting beam 
according to the invention is provided in order to satisfy the demand. 
It is an object of the invention, as a result of bonding a connecting pad 
of a magnetic head element to a signal conductor of a supporting beam, to 
enable both mechanical coupling of the magnetic head element to the 
supporting beam and an electrical connection of the connecting pad of the 
magnetic head element to the signal conductor of the supporting beam to be 
conducted at one time. 
It is another object of the invention to, in addition to the bonding of the 
connecting pad to the signal conductor, allow an auxiliary pad to be 
bonded to the signal conductor, whereby the mechanical coupling strength 
of the magnetic head element to the supporting beam is enhanced so that 
the stability of the state of attaching the magnetic head element to the 
supporting beam is improved. 
It is a further object of the invention to, even in the case where a 
connecting pad and an auxiliary pad are separately bonded to a signal 
conductor, enable a work of bonding a portion in which bonding is lately 
done, to be conducted under the state where heat of the portion to be 
bonded is prevented from affecting another bonding portion in which 
bonding has been already completed. 
The method of bonding a magnetic head element to a supporting beam 
according to the invention is a method in which a connecting pad for 
mechanical and electrical connections and an auxiliary pad for increasing 
a mechanical coupling strength in said magnetic head element are bonded to 
a signal conductor in said supporting beam, said method comprising the 
steps of: previously forming a groove for blocking heat transmission 
between bonding portions in said signal conductor to which portions said 
pads are to be bonded, respectively, said groove being disposed between 
said bonding portions; contacting one of said pads with one of said 
bonding portions and heating the contact portion, thereby bonding the one 
pad with the one bonding portion; and contacting the other pad with the 
other bonding portion and heating the contact portion, thereby bonding the 
other pad with the other bonding portion under a state where heat 
transmission from the other bonding portion to the one bonding portion is 
blocked by said groove. 
According to the invention, when a magnetic head element is to be bonded to 
a supporting beam, a connecting pad is bonded to a signal conductor. 
Consequently, a mechanical coupling of the magnetic head element to the 
supporting beam, and an electrical connection of the connecting pad to the 
signal conductor can be simultaneously conducted so that the working 
efficiency is high. 
In addition to the connecting pad, furthermore, an auxiliary pad also is 
bonded to the signal conductor. Therefore, the mechanical coupling 
strength of the magnetic head element to the supporting beam is improved. 
As a result, an effect that the stability of the state of attaching the 
magnetic head element to the supporting beam is very enhanced is attained. 
In the invention, moreover, two pads, i.e., the connecting pad and the 
auxiliary pad are bonded to the signal conductor as described above. In 
order to obtain a large bonding strength in each bonding portion, it is 
preferable to sufficiently heat the contact portion between each of the 
pads and the respective bonding portion of the signal conductor. In this 
case, when the heating is sufficiently done for a long period, its heat is 
transmitted to another bonding portion in which bonding has been already 
completed, thereby breaking the bonding of the other bonding portion and 
the respective pad. By contrast, in the invention, a groove which is 
disposed between a bonding portion and another bonding portion blocks the 
transmission of heat. As a result, even when the heating is sufficiently 
done in a portion where the bonding is lately conducted, its heat is 
blocked from being transmitted to another portion in which bonding has 
been already completed, thereby preventing the bonding in the other 
portion from being broken. This enables a large bonding strength to be 
obtained by sufficient heating. Furthermore, a bonding portion is 
prevented from erroneously broken, so that the bonding operation correctly 
proceeds. 
Other objects and advantages of the invention will become apparent during 
the following discussion of the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Hereinafter, FIGS. 1 to 3 showing an embodiment of the invention will be 
described. In the figures, the same reference numerals as those of FIG. 4 
designate functionally equivalent components and their description may be 
duplicated. Therefore, the duplicated description is omitted. Referring to 
the figures, connecting pads 13 of the head element 5 are used for 
mechanically coupling the head element 5 to the supporting beam 4 and 
electrically connecting a signal circuit of the head element 5 to the 
signal conductor of the supporting beam 4. For example, both the length 
and width W1 and W2 of the connecting pads 13 have a dimension of about 75 
.mu.m. The upper face 13a of each connecting pad 13 serves as a bonding 
face in the bonding which will be described later. In order to allow the 
upper faces 13a to surely contact with the signal conductors of the 
supporting beam 4, the upper faces 13a are slightly protruded (for 
example, by about 0.5 .mu.m) with respect to the upper face 7a of the body 
7 of the head element 5. The upper faces 13a are configured by a material 
which is hardly oxidized, such as gold so that the surface control is 
facilitated (the formation of an oxide film is suppressed). For example, 
the upper face 13a configured by gold may be realized by forming the whole 
of the connecting pad 13 by gold. Alternatively, the upper face may be 
provided with gold by plating or forming a thin film on the connecting pad 
13 made of another material. The reference numeral 12a in FIG. 2 
designates a signal circuit connected to the connecting pads 13. Terminals 
of a coil are shown as an example of the circuit. The reference numeral 14 
designates auxiliary pads which are disposed in an auxiliary manner in 
order to further strengthen the mechanical coupling of the head element 5 
to the supporting beam 4. The auxiliary pads 14 are fixed to the body 7, 
but, unlike the connecting pads 13, are not electrically connected to the 
inside of the head element 5. For example, the auxiliary pads 14 are made 
by the same material as the connecting pads 13 and have the same size as 
the connecting pads. When the connecting pads 13 are formed by thin film 
forming means, for example, the auxiliary pads 14 may be formed together 
with the connecting pads. 
The supporting beam 4 has a structure in which three layers: a base 17 
configured by, for example, a stainless steel spring plate; an insulating 
layer 18; and signal conductors 19 made of, for example, copper are 
integrally stacked. The base 17 and the signal conductors 19 contribute to 
the resilience of the supporting beam 4. The reference numeral 19a 
designates a face of each signal conductor 19 on the side where the signal 
conductor is to be bonded to the pads 13 and 14. Each face 19a is formed 
by gold with the same object as that of the upper faces 13a of the 
connecting pads 13. The reference numeral 21 designates bonding portions 
to which the connecting pads 13 of the magnetic head 5 are to be bonded, 
respectively. In order to realize a signal transmission between the 
connecting pads 13 and the signal conductors 19, each bonding portion 21 
is disposed in the respective signal conductor 19. As illustrated, each 
bonding portion 21 is formed so as to have a small width so that the heat 
capacity of the bonding portion itself is reduced. Grooves 22 and 23 which 
are respectively formed on the both sides of each bonding portion are used 
for blocking heat transmission from each bonding portion 21 to the area 
surrounding the bonding portion. The reference numeral 24 designates 
bonding portions to which the auxiliary pads 14 are to be bonded, 
respectively. In the same manner as the bonding portions 21, the bonding 
portions 24 are formed so as to have a small width and grooves 22 and 23 
are respectively formed on the both sides of each bonding portion 24. 
Among the grooves 22 and 23, particularly, the grooves positioned between 
the bonding portions 21 and 24 are disposed also with a further object of 
blocking heat transmission between the bonding portions 21 and 24. The 
portions 25 in the base 17 are through holes which are formed so as to 
allow the tip end of a presser for the bonding operation which will be 
described later, to pressingly contact with the bonding portions 21 and 24 
without touching the base 17. In order to suppress the lowering in 
strength of the base 17, the through holes 25 are preferably formed so as 
to have a size which is as small as possible but in the range where the 
presser is prevented from contacting with the base. The reference numeral 
26 designates through holes which are formed in the insulating layer 18 
with the same object as those of the through holes 25. 
Next, the operation of bonding the head element 5 to the supporting beam 4 
will be described. At first, the supporting beam 4 and the head element 5 
are supported by respective jigs. The jigs are then operated so that, as 
shown in FIG. 2, the bonding faces 21a and 24a of the bonding portions 21 
and 24 of the signal conductors 19 contact in an overlapping manner with 
the bonding faces 13a and 14a of the connecting pads 13 and the auxiliary 
pads 14 of the head element 5. In this contact, the bonding faces 13a and 
14a are caused to surely contact with the faces 21a and 24a because the 
bonding faces 13a and 14a are protruded. As shown in FIG. 3, the 
connecting pads 13 and the auxiliary pads 14 can be observed through the 
grooves 22 and 23. Therefore, the operation of positioning the bonding 
portions 21 and 24 with respect to the connecting pads 13 and the 
auxiliary pads 14 can be facilitated. As shown in FIG. 2, the tip of a 
thermal-compression bonding presser 27 is then pressed against one of the 
bonding portions 21 via the through holes 25 and 26 and heat generated by 
a heater 28 is supplied to the bonding portion 21. The thermal-compression 
bonding presser 27 is used for applying a pressing force to an area where 
the bonding is to be conducted and transmitting heat for the bonding, 
generated by the heater 28, to the area. The pressing is conducted by 
applying a predetermined contact pressure. The pressing and heating of the 
presser 27 supply a pressure and heat to the contact portion 29 between 
the faces 21a and 13a so that the contact portion is subjected to the 
thermal-compression bonding, with the result that the bonding portion 21 
and the connecting pad 13 are integrally bonded to each other. This 
bonding causes the bonding portion 21 and the connecting pad 13 to be 
mechanically coupled to each other. As a result, a state in which the 
magnetic head element 5 is mechanically fixed to the supporting beam 4 is 
obtained. This bonding causes also the bonding portion 21 and connecting 
pad 13 to be electrically connected each other so that a state in which 
the signal circuit of the magnetic head element 5 is electrically coupled 
to the signal conductor 19. For example, the tip end face of the 
thermal-compression bonding presser 27 has a rectangular shape in which 
one edge is equal to or shorter than about 100 .mu.m. Alternatively, the 
end face may have a circular shape the diameter of which is equal to or 
shorter than about 100 .mu.m. In order to ensure an adequate bonding 
state, preferably, the period when the pressing of the thermal-compression 
bonding presser 27 is done is previously determined in accordance with 
results of tests which are conducted with using samples of the supporting 
beam 4 and the head element 5. 
In the thermal-compression bonding of the bonding portion 21, a phenomenon 
that the temperature of the bonding portion 21 is rapidly raised occurs 
because the portion 21 has a small width so as to have a reduced heat 
capacity. Furthermore, the presence of the grooves 22 and 23 restricts the 
path of heat transmission to the signal conductor 19 surrounding the 
bonding portion 21, to end portions 21b and 21c of the bonding portion 21. 
Therefore, heat of the bonding portion 21 hardly enters the surrounding 
signal conductor 19. Also this phenomenon enhances the rapid temperature 
rise of the bonding portion 21. These phenomena enable the bonding 
operation to be rapidly completed. Such rapid completion of the bonding 
operation reduces the possibility that the heat is transmitted to the 
interior of the head element 5, thereby preventing the properties of the 
head element from being impaired. Moreover, the reduced amount of 
heat-transmitted to the surrounding signal conductor 19 inhibits the 
signal conductor 19 from being raised in temperature and hence prevents 
the spring properties of the conductor from being degraded. 
When the above-mentioned bonding between the bonding portion 21 and the 
connecting pad 13 is ended, the thermal-compression bonding presser 27 is 
then pressed against one of the bonding portions 24 and the bonding 
between the bonding portion 24 and one of the auxiliary pads 14 is 
conducted in the same manner as that for the bonding portion 21. It is a 
matter of course that also the bonding of the bonding portion 24 can 
attain the same effects as those of the bonding of the bonding portion 21. 
In addition, the bonding can attain a further effect that the grooves 22 
and 23 block the heat of the bonding portion 24 from being transmitted to 
the bonding portion 21 via the signal conductor 19 surrounding the bonding 
portion. Particularly, the groove 22 blocks the heat from being directly 
transmitted from the bonding portion 24 to the bonding portion 21. 
Consequently, an accident such as that the temperature of the bonding 
portion 21 in which the bonding has been already completed is raised and 
the bonding is broken does not occur at all. As a result of the bonding 
between the bonding portion 24 and the auxiliary pad 14, the state of 
mechanically coupling the magnetic head element 5 to the supporting beam 4 
becomes very strong. 
When the operations of bonding all the connecting pads 13 and the auxiliary 
pads 14 are ended, the supporting beam 4 and the head element 5 are 
detached from the jigs, thereby completing the bonding of the head element 
5 to the supporting beam 4. In the bonding described above, the bonding 
portions 21 and 24 are directly (without interposition) bonded with the 
connecting pads 13 and the auxiliary pads 14. In the completed head 3 
which is obtained after the bonding, therefore, the dimension L (see FIG. 
5) between the reference face 4b and the contact face 6a is highly 
accurate. The reference face 4b is a face for conducting attachment of the 
basal portion 4a of the supporting beam 4 to the supporting arm 2. The 
dimension L is a dimension obtained when the supporting beam 4 is in the 
free state as shown in FIG. 5. The high accuracy of the dimension L allows 
the contact face 6a to contact with the surface 1a of a disk with a 
predetermined contact pressure in a use state such as shown in FIG. 4. 
Either of the bonding portions 21 and 24 may be first subjected to the 
bonding operation. The upper faces 13a and 14a of the connecting pads 13 
and the auxiliary pads 14 of the head element 5 may be configured so as to 
be equal in level to or slightly lower than the upper face 7a of the body 
7. In this case, the faces 21a and 24a of the bonding portions 21 and 24 
of the signal conductor 19 which respectively oppose the upper faces may 
be formed so as to be protruded, thereby enabling the faces 21a and 24a 
and the faces 13a and 14a to contact with each other. The width W3 of each 
of the bonding portions 21 and 24 may be greater than the dimension in the 
same direction of the connecting pads 13 and the auxiliary pads 14. 
Alternatively, the aforementioned bonding may be conducted in the following 
manner in order that an adverse effect due to heat on the signal 
conductors and the head element is reduced and the bonding is further 
rapidly conducted. In place of the thermal-compression bonding presser 27, 
an ultrasonic presser is pressed against each bonding portion in the same 
manner as the presser 27. An ultrasonic presser is a part of an ultrasonic 
machine which is used for transmitting ultrasonic vibration generated by 
an ultrasonic transducer to a workpiece. Ultrasonic wave energy is applied 
from the ultrasonic presser to the contact face 29. The bonding may be 
conducted by this method. The bonding may be conducted by so-called 
ultrasonic bonding means. In the case of the ultrasonic bonding, the faces 
21a and 13a of the contact portion 29 are caused to diffuse into each 
other by the applied ultrasonic wave energy. When the application of the 
ultrasonic wave from the ultrasonic presser is then halted, the diffusion 
is stopped. This stop of the diffusion causes the contact portion 29 to 
which the ultrasonic wave energy has been applied, to instantaneously 
solidify, thereby realizing the bonding of the bonding portion 21 and the 
connecting pad 13. In this case, the diffusion occurs in a very restricted 
area, or only in the contact portion 29. Even when a small amount of 
ultrasonic wave energy is given, therefore, gold in the faces 21a and 13a 
of the contact portion can surely diffuse, with the result that the 
bonding can be surely performed. Since the bonding is done by applying 
ultrasonic wave energy, the generation of heat is restricted only to the 
contact portion 29 so that the portions of the signal conductor 19 other 
than the contact portion 29 and the interior of the head element 5 other 
than the contact portion 29 are hardly raised in temperature. 
Consequently, these properties of the components are prevented from being 
impaired. Since the contact portion 29 is caused to diffuse by locally 
applying ultrasonic wave energy to only the contact portion 29 as 
described above, the diffusion can be immediately stopped by halting the 
application of the ultrasonic wave. This can attain an effect that the 
bonding operation can be conducted very rapidly so as to improve the 
bonding efficiency. 
FIG. 6 shows another example of a shape of the groove for blocking heat 
transmission in a signal conductor. Grooves 31 for blocking heat 
transmission are formed around bonding portions 21e and 24e or in the 
three sides of each bonding portion including the side 21' or 24' on the 
side of the other bonding portion, respectively. When the grooves 31 are 
formed into such a shape, heat transmission from the bonding portions 21e 
and 24e to the surrounding signal conductor 19e can be further reduced. As 
a result, the above-mentioned rapidity of the bonding operation and 
reduction of the adverse effect on the surrounding can be further 
enhanced. The components which may be functionally identical or equivalent 
to those shown in the previous figures and description of which may be 
duplicated are designated by the same reference numerals as those used in 
the figures and affixed by letter "e", and their duplicated description is 
omitted. (Similarly, also such components shown in the succeeding figures 
are designated by the same reference numerals affixed by letter "f" or "g" 
and their duplicated description is omitted.) 
FIG. 7 shows a further example of a shape of the groove for blocking heat 
transmission between bonding portions 21f and 24f in a signal conductor 
19f. A sole groove 32 for blocking heat transmission is laterally formed 
between the bonding portions 21f and 24f. Also in this configuration, the 
groove 32 blocks heat applied in the bonding of one of the bonding 
portions (e.g., the bonding portion 24f) from being linearly transmitted 
to the other bonding portion 21f. Consequently, heat must be transmitted 
to the other bonding portion while detouring the groove 32, whereby heat 
transmission to the other bonding portion is suppressed. 
FIG. 8 shows another embodiment in which the bonding of the magnetic head 
element 5 to the supporting beam 4 is realized by other means. In addition 
to the bonding by means of the bonding portions 21 and 24, the bonding of 
the magnetic head element 5 to the supporting beam 4 is further done by 
means of an adhesive agent 33 in order to further strengthen the bonding 
of the head element 5 to the supporting beam 4. The adhesive agent 33 
makes adhesion of an overlapped area between the supporting beam 4 and the 
magnetic head element 5, for example, the lower face of the supporting 
beam 4 (in the embodiment, the lower face 19a of the signal conductor 19) 
and the upper face 7a of the body 7. The adhering by means of the adhesive 
agent 33 is conducted after the aforementioned bonding operation of the 
bonding portions 21 and 24. The adhesive agent 33 can be filled into the 
space between the upper and lower faces 7a and 19a while, for example, the 
through holes 25 and 26 are used as filling holes. This filling causes the 
upper and lower faces 19a and 7a to adhere to each other by means of the 
adhesive agent 33 so that the bonding of the head element 5 to the 
supporting beam 4 becomes very strong. Preferably, an agent which is 
excellent in permeability and electrical insulation property may be used 
as the adhesive agent. 
FIG. 9 shows an example in which a supporting beam 4g is configured in a 
different manner. A hole 34 for filling the adhesive agent is disposed in 
an area where the supporting beam 4g overlaps with the head element 5. The 
filling hole 34 is formed so as to communicate with a gap 35 between a 
pair of signal conductors 19g so that the adhesive agent surely flows into 
the space between the lower face of the signal conductor 19g and the upper 
face of the body 7. Consequently, the adhesive agent filled through the 
filling hole 34 can be impregnated into the whole space between the lower 
face of the signal conductor 19g and the upper face of the body 7, whereby 
the adhering can be ensured. 
As many apparently widely different embodiments of this invention may be 
made without departing from the spirit and scope thereof, it is to be 
understood that the invention is not limited to the specific embodiments 
thereof except as defined in the appended claims.