JP2002067337A - Ink jet head and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To join an actuator electrode to FPC electrodes by heating in a state they are aligned with high accuracy when an ink jet head of drop-on-demand type is to be manufactured. SOLUTION: As to a method for arranging in parallel a plurality of FPC electrodes (electrode pattern) 10b on a base film 11 of an FPC 10 and joining by heating the FPC electrodes to the actuator electrode 51b corresponds to them, an expansion cumulation of the base film in heating and joining is divided by forming openings 22 on both sides of the FPC electrodes of the base film (an expansion of the base film is absorbed by the openings 22) and they are joined with high accuracy. Preferably the openings 22 have a length longer than a width of a joining regions (heating regions) R3 and the width of the joining regions R3 may be set within the length of the openings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet head (recording) for a drop-on-demand type ink-jet recording apparatus which forms and discharges ink droplets only when recording is required and performs ink recording on a desired recording medium. More particularly, the present invention relates to an electrostatic inkjet head for discharging ink using electrostatic force and a method for manufacturing the same. An application field of the present invention is a recording head of an image forming apparatus such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art An ink jet recording apparatus does not require processes such as development and fixing, and can perform non-contact recording, so that noise during recording is extremely low, high-speed printing is possible, and ink flexibility is high. It has many advantages, such as being able to use inexpensive plain paper. Among them, the so-called drop-on-demand type, which ejects ink droplets only when recording is necessary, does not require collection of ink droplets unnecessary for recording, so maintenance is easy and the device configuration is small. Because it is cheaper, it is currently attracting attention.

An ink jet head constituting an ink jet recording apparatus has a nozzle plate in which a plurality of nozzle holes are formed, and a pressurized liquid chamber (ink liquid chamber) in which the nozzle holes communicate.
And an actuator (driving means). The actuator pressurizes the ink in the pressurized liquid chamber to discharge ink droplets from the nozzle holes.

The drop-on-demand type ink jet head is provided with an electrostatic actuator,
There is known a device which discharges ink by driving the electrostatic actuator by an electrostatic force to vibrate a diaphragm. This method using an electrostatic actuator has advantages of small size, high density, high printing quality, and long life.

A technique relating to a thermal head using an FPC (flexible printed cable, also called a flexible printed wiring board or a flexible printed board) for forming an image recording apparatus such as a facsimile is disclosed in Japanese Unexamined Patent Publication (Kokai) No. H08-0849. JP 230224 and JP-A-9
No. 183245.

The former JP-A-8-230224 discloses a bonding method and a connecting method which aims to provide a reliable thermal head by reliably and firmly connecting a conductor layer of a head substrate and a wiring of an FPC. A thermal head according to this joining method is disclosed. That is, the above-mentioned joining method is based on filling the resin adhesive around the solder for joining the conductor layer and the wiring.
This is a method for joining a PC wiring board. The thermal head includes a head substrate having a plurality of heating elements and a plurality of conductor layers electrically connected to the heating elements, and an FPC having a plurality of wirings. In a thermal head in which each wiring of an FPC is joined to a conductor layer via solder, a resin adhesive is filled between the head substrate and the FPC so as to surround the solder for joining the conductor layer and the wiring. It is characterized by having.

Japanese Patent Application Laid-Open No. Hei 9-183245 discloses a resin sealing material for sealing an FPC joint of a thermal head and a method for manufacturing a thermal head using the same. The method of manufacturing a thermal head includes a head substrate having a plurality of heating elements and a plurality of conductor layers electrically connected to the heating elements, and an FPC having a plurality of wirings. FP for conductor layer
C. A method of manufacturing a thermal head in which each wiring of C is joined via solder, wherein a predetermined resin sealing is provided between the head substrate and the FPC so as to surround the solder for joining the conductor layer and the wiring. A method for manufacturing a thermal head, comprising: a step of filling a stopper; and a step of heating and thermally curing the resin sealing agent.

Japanese Patent Application Laid-Open No. 7-52491 discloses that
A so-called serial type recording apparatus that performs recording by moving a carriage on which a recording head is mounted and that detects the position of the carriage by a magnetic linear encoder is disclosed. Further, this patent publication describes a structure in which a conductor of an FPC for outputting a detection result of a magnetoresistive element (MR element) constituting a magnetic head is soldered on an electrode. In this soldering structure, a lower solder is applied on an electrode, a solder layer is formed thereon, and the conductor is soldered.

In a drop-on-demand type ink jet head, a vibrating plate is provided on one side of a pressurized liquid chamber, and the vibrating plate is vibrated by driving an actuator to discharge ink liquid in the pressurized liquid chamber from a nozzle. It is configured to make it. Further, as this ink jet head, a type in which an electrode portion of an actuator is joined to an electrode portion of an FPC and the actuator is driven by a voltage applied via the FPC is widely known.

However, the actuator electrode and the F
In the connection with the PC electrode portion, if the electrodes are not properly aligned, conduction failure occurs, and as a result, a problem arises in that the head does not function properly.

The causes of the displacement between the two electrodes can be roughly divided into (1) a dimensional error of the actuator electrode portion, (2) a dimensional error of the FPC electrode portion, (3) a positioning error of the two electrodes, and ( 4) "Position shift" at the time of joining
One.

The above (1) to (3) must be dealt with by increasing the precision of the parts and the precision of the joining device. Regarding the above (4), in the heating type joining method, there is a problem that the material expands due to heat. That is, if a long FPC is heated and joined, even if one end is aligned with high accuracy, the FPC is stretched due to thermal expansion, and "position displacement" occurs on the other side. Although there is a method of determining the size of the FPC in consideration of the amount of elongation in advance, a satisfactory solution cannot be obtained with this alone in terms of mass production due to variations in materials, variations in bonding conditions, and the like.

In a conventional electrostatic ink jet head,
FIG. 7 shows the joint structure between the actuator electrode and the FPC electrode.
(Plan view). FIG. 8 is an enlarged view of a portion B in FIG. In these figures, reference numeral 54 denotes an FPC,
Reference numeral 54b denotes an FPC electrode (electrode pattern), reference numeral 54c denotes a base film, and an elongated rectangular region denoted by reference numeral R3 denotes a bonding region for electrically connecting the actuator electrode 51b and the FPC electrode 54b. Other configurations are
This is the same as the electrostatic inkjet head according to the present invention shown in FIGS. 1 and 2 described later.

However, as the number of nozzle holes in the ink jet head increases, the number of electrode patterns 54b also increases, and the width of the FPC 54 (the width of the base film 54c: the vertical dimension in FIG. 8) naturally increases. Then, as described above, it is difficult to accurately align the actuator electrode 51b and the FPC electrode 54b when joining the actuator electrode 51b and the FPC electrode 54b due to several factors. In particular, when the electrodes are joined by heating, the thermal expansion of the base film (usually, polyimide, which is a resin material having high heat resistance) due to heating is not negligible depending on the type of the material. In severe cases, the electrodes may not hit each other. This is because the thermal expansion of the base film is accumulated.

[0015]

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a drop-on-demand type ink jet head in which an actuator electrode and an FPC electrode are accurately aligned and joined with a simple structure. It is an object of the present invention to provide an electrode bonding structure that can be used. A second object of the present invention is to manufacture a drop-on-demand type ink jet head by heating and joining an actuator electrode and an FPC electrode with these electrodes positioned with high precision. It is to provide an electrode bonding method.

[0016]

According to a first aspect of the present invention, there is provided an ink jet head having a plurality of nozzle holes, a pressurized liquid chamber and an actuator provided corresponding to each of the nozzle holes. A plurality of electrodes (F) of an FPC for transmitting a drive signal from a drive circuit to an actuator
PC electrodes) are connected to the electrodes of the corresponding actuators (actuator electrodes), respectively.
The actuator electrode is joined to the FPC electrode in a state where a notch is formed in a region between the electrodes.

According to a second aspect of the present invention, in the ink jet head according to the first aspect, the notch is a slit formed at an end of an FPC base film.

According to a third aspect of the present invention, in the ink jet head according to the first aspect, the cutout portion is an opening formed at an end of an FPC base film.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an ink jet head, comprising: a plurality of nozzle holes; a pressurized liquid chamber and an actuator provided corresponding to each of the nozzle holes; In the method of manufacturing an inkjet head in which a plurality of electrodes (FPC electrodes) of the FPC that transmit the drive signals of the FPC to the actuators are respectively joined to the electrodes (actuator electrodes) of the corresponding actuators, the adjacent FPC base film F
After forming the notch in the region between the PC electrodes, the heat bonding between the actuator electrode and the FPC electrode is performed separately at a different timing for each FPC base film portion divided by the notch. And

According to a fifth aspect of the present invention, there is provided a method of manufacturing an ink jet head according to the fourth aspect, wherein the heating and joining of the actuator electrode and the FPC electrode is performed by heating only the joining region.

According to a sixth aspect of the present invention, in the method for manufacturing an ink jet head according to the fourth or fifth aspect, the length of the cutout portion is made longer than a joining region between the actuator electrode and the FPC electrode, and the joining region is made longer. Is formed within the length of the notched portion.

According to a seventh aspect of the invention, there is provided a method of manufacturing an ink jet head according to the sixth aspect, wherein the notch is a slit formed at an end of an FPC base film.

According to a eighth aspect of the present invention, in the method for manufacturing an ink jet head according to the sixth aspect, the notch is an opening formed at an end of an FPC base film.

In the ink-jet head according to the first aspect and the method for manufacturing an ink-jet head according to the fourth aspect, a slit or an opening is formed as an opening in the FPC base film between adjacent FPC electrodes.
Since the heat bonding region in the base film of the FPC is divided, the accumulation of expansion at the time of bonding is divided by the lacking portion, and the heat bonding between the actuator electrode and the FPC electrode can be performed with a high degree of positioning accuracy. it can.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment The structure of an electrostatic ink jet head and the principle of ink ejection will be described. FIG. 1 is an exploded perspective view of an inkjet head utilizing electrostatic force, and FIG. 2 is a cross-sectional view showing a main structure of the inkjet head. FIG. 3 is a plan view showing a joint structure between an actuator electrode and an FPC electrode in the electrostatic ink jet head, and FIG. 4 is an enlarged view of a portion A in FIG.

As shown in FIGS. 1 and 2, the electrostatic type ink jet head includes an electrostatic actuator 51, a nozzle plate 52, a driver IC 53, an FPC 10, and a frame 5.
5, a filter 56 and a joint 57.
Reference numeral 52a is a nozzle hole. Electrostatic actuator 51
Are formed by a silicon process, and the nozzle plate 52 is formed by a nickel electroforming process. A description of a method of manufacturing the electrostatic actuator 51 and the nozzle plate 52 will be omitted.

Next, an example of a method of assembling the above-mentioned electrostatic ink jet head will be described with reference to FIGS.
First, the electrostatic actuator 51 and the FPC 10 are electrically connected by an anisotropic conductive film (actuator electrode 5).
1b and FPC electrode 10b). In FPC10,
The driver IC 53 is mounted by wire bonding.

Then, in order to join the nozzle plate 52 and the electrostatic actuator 51, an adhesive (not shown) is applied to the upper surface of the pressurized liquid chamber (silicon liquid chamber) 61. When the pressurized liquid chamber 61 and the nozzle plate 52 are joined by the above-mentioned adhesive, since the protrusion of the adhesive affects the ink ejection characteristics from the nozzle holes 52a, the adhesive applied film thickness is 1
It needs to be around μm. Therefore, the pressurized liquid chamber 61
It is desirable to apply the adhesive to the upper surface by a transfer method. For example, an adhesive is applied to the roller surface with a doctor blade to make it thinner, the adhesive is transferred from the roller by a transfer pad, and the adhesive is further transferred from the transfer pad to the upper surface of the pressurized liquid chamber. Further, an adhesive, that is, a diaphragm gap sealing agent 62a is applied to seal the gap (the entrance of the vibration chamber) of the diaphragm 62. If moisture enters the inside of the vibration chamber, the diaphragm 62 will not be displaced. In order to position the nozzle plate 52 and the pressurized liquid chamber 61, an ultraviolet-curing adhesive for temporary joining or an instant adhesive is applied to the corner of the pressurized liquid chamber 61.

Then, the nozzle plate 52 formed by nickel electroforming and the electrostatic actuator 51 coated with an adhesive are aligned and pre-pressed. here,
In the case of an ultraviolet-curable adhesive, the adhesive is cured by irradiating ultraviolet rays, and then the main pressure is applied to cure the adhesive. If the electrostatic actuator 51 is long, the pressurized liquid chamber 61 and the nozzle plate 52 (made of Ni or SUS) are used for heating and joining.
Are warped due to the difference in linear expansion coefficient. When warpage occurs, the electrostatic actuator 51 is broken by internal stress. As described above, it is preferable that the curing temperature of the adhesive is lower. Therefore, it is desirable to use, for example, a two-component mixed type (room temperature curing type) epoxy adhesive. The curing temperature is preferably as low as possible, but 40 to 100 ° C. is practical and desirable.

The joint 57 for supplying ink from an ink supply tank (not shown) or an ink cartridge (not shown) is bonded to the frame 55 to which the filter 56 is heat-welded. An adhesive is applied to the frame 55 to bond the electrostatic actuator 51 and the nozzle plate 52 together, and the electrostatic actuator is aligned and bonded.

In FIG. 1, reference numeral 51a denotes a step formed on both sides of the upper portion of the electrostatic actuator 51. On the step 51a, as shown in FIG.
1b is formed. The electrode 51b includes a common electrode and an individual electrode. The FP patterned as shown in FIGS. 2 and 4 is provided on the lower surface of the top 10a of the FPC 10.
A C electrode (electrode pattern) 10b is formed. Then, the electrical connection between the actuator electrode 51b and the FPC electrode 10b is performed by an anisotropic conductive film (anisotropic conductive film). 1 and 2, reference numeral 11 denotes an FPC.
Reference numeral 63 denotes a nozzle plate sealant, reference numeral 64 denotes a fluid resistance, and reference numeral 65 denotes a common liquid chamber flow path.

In such a configuration, by applying a pulse voltage to the individual electrode, the diaphragm 62 is deformed toward the individual electrode by an electrostatic force. Then, the ink flows from the common liquid chamber (not shown) to the common liquid chamber flow path 65 and the fluid resistance 6.
4 and flows into the pressurized liquid chamber (pressure generating chamber) 61, and its volume increases. Here, the release of the pulse voltage eliminates the electrostatic force, and the diaphragm 62 returns to the original state. The pressure of the pressurized liquid chamber 61 is increased by the elastic force of the vibration plate 62, and ink is ejected from the nozzle holes 52a.

As shown in FIGS. 3 and 4, a slit 21 extending in the length direction (the left-right direction in FIG. 4) is provided at the center of the width direction (the vertical direction in FIG. 4) of the base film 11 of the FPC 10. Articles are formed. The elongated rectangular area indicated by the reference symbol R3 is a joining area where the actuator electrode 51b and the FPC electrode 10b are electrically connected. Although FIG. 3 simplifies the description of the FPC electrode 10b and shows only the two sides, the FPC electrode 10b is actually formed over the entire width of the base film 11 and a driver IC is formed.
2, and the left end of FIG. 2, that is, the end (not shown) on the opposite side to the above-mentioned joining area, is connected to a connector part which contacts the transmitted signal.

By the way, when the number of nozzle holes of the ink jet head increases, the number of the electrode patterns 10b also increases, and the width of the FPC 10 (the width of the base film 11) naturally increases. Then, as described above, the actuator electrode 51b and the electrode pattern 10b
It becomes difficult to accurately align with As already described, in the case of heat joining, the thermal expansion of the base film 11 due to heating is large, and in severe cases, the electrodes may not be able to contact each other. In view of the above, the present invention prevents the above-mentioned problem by applying a means for preventing the thermal expansion of the base film from accumulating.

That is, in the present embodiment, as shown in FIGS.
A slit 21 is formed at a position between 0b and 10b from the end of the base film 11 in parallel with the FPC electrode 10b.
By providing the slits 21, the joining region portion of the base film 11 is divided into the first divided portion 11 a (the base film portion divided by the slit) and the second divided portion 1.
1b (base film part divided by slit)
And the cumulative expansion at the time of joining
The number can be divided by one. Although an effect can be obtained even if the slit 21 is a mere notch having a width of almost zero, a slit (a band) having a little width is more effective. From what the width of the base film,
Whether these factors need to be considered depends on the required accuracy, the constituent material of the base film, the heating temperature, etc., but generally the accuracy is several μm to several tens μm, polyimide film, soldering or anisotropic conductive In the case of the heat bonding of the films, when the width of the base film exceeds about 20 mm, it is necessary to take measures against the displacement of the electrodes.

As shown in FIG. 4, it is preferable that the length of the slit 21 be longer than the width of the joining region R3, and that the width of the joining region R3 be located within the length of the slit 21. In the FPC 10 of FIG. 4, a region R1 on the right side of the alternate long and short dash line indicates a portion where the bonding surface side of the electrode pattern for bonding is exposed. A region R2 on the left side of the dashed line indicates a portion where the electrode pattern 10b is covered on both sides with a polyimide film. Although one slit 21 is formed in FIG. 4, a plurality of slits 21 may be formed.

When the joining region R1 is divided into two by the slits 21 as shown in FIGS. 3 and 4, when the plurality of FPC electrodes are respectively joined to the corresponding actuator electrodes, the timing of the electrode joining in the first dividing portion 11a is determined. In addition, it is preferable that the timing of the electrode joining in the second divided portion 11b be made different, which is effective when higher joining accuracy is desired. For example, after the electrode joining in the first division 11a is completed, the electrode joining in the second division 11b is performed. In this case, after the electrodes are aligned (positioned) for the first division 11a and joined, the second division 11b may be again aligned and joined.

The greater the number of slits 21, the greater the effect of dividing the accumulation of expansion during electrode joining, so that highly accurate joining can be performed. When a large number of slits 21 are formed, the timing may be shifted for each divided portion, or the electrodes may be joined together at several divided portions. If the number of slits is too large, the number of narrow band-shaped portions formed at one end of the base film increases. In this case, the movement of the one end of the band-shaped portion is free. In some cases, difficulties may occur in the dimensional accuracy and handleability of the device.

Second Embodiment In the base film 11 shown in FIG. 4, when a large number of slits are provided, there is a problem that the handleability of the base film is reduced. In contrast, the base film 11 shown in FIG.
By forming the openings 22 on both sides of each of the electrode patterns 10b, the effect of dividing the accumulation of expansion at the time of electrode bonding can be improved, and high-precision bonding can be performed, and the above-mentioned problem is solved. . This opening 22
In the same manner as in the case of FIG. 4, the length is changed to the joining region (heating region).
It is preferable that the width is larger than the width of R3 and that the width of the joining region R3 is located within the length of the opening 22. With this base film, high-precision bonding is possible even when electrode bonding is performed at once for the entire FPC. In addition, since one ends of the base film are connected to each other, a decrease in dimensional accuracy and a decrease in handleability of the base film in FIG. 4 do not occur.

Third Embodiment A joint structure between an actuator electrode and an FPC electrode shown in FIG. 6 is a modified example of FIG. That is, while a large number of small openings 22 are formed independently in FIG. 5, FIG.
In this example, one large rectangular opening 23 is formed in a form in which these openings are connected to each other. As a result, FIG.
The same effect as that of the above joint structure can be obtained.

As described above, the embodiment of the present invention has been described with respect to the case where soldering is used. However, it is needless to say that the present invention can be applied to other joining methods involving heating and using an anisotropic conductive film or the like.

[0042]

As is apparent from the above description, claim 1
According to the inkjet head according to the first aspect and the manufacturing method of the inkjet head according to the fourth aspect, the notch is formed in the portion between the adjacent FPC electrodes of the FPC base film, so that the heat bonding region in the FPC base film is divided. Since the cumulative expansion at the time of bonding is divided by the above-described cutout portion (the cumulative dimensional error due to the thermal expansion of the FPC base film at the time of thermal bonding is divided), the thermal bonding between the actuator electrode and the FPC electrode can be advanced. Can be performed with a positioning accuracy of

In the method for manufacturing an ink jet head according to the fifth aspect, the heating and joining of the actuator electrode and the FPC electrode are performed by heating only these joining regions, so that the influence of heating at the time of joining is minimized. As compared with the manufacturing method of the fourth aspect, more accurate electrode bonding can be performed.

According to a sixth aspect of the present invention, in the method of manufacturing an ink jet head, the length of the cut-out portion is made longer than the joining region between the actuator electrode and the FPC electrode, and the joining region is formed in the cut-out portion. Since the notch portion is formed so as to be positioned within the length of the heat-bonded portion, the heat bonding region in the FPC base film has a shape divided by the notch portion (slit or opening).
It is no longer affected by thermal expansion during heat bonding. In particular, in the manufacturing method according to claim 8, since an opening is formed as the cutout portion, unlike the FPC base film according to claim 7, in which a slit is formed as the cutout portion, the end portion is divided. Since it is not performed, there is no decrease in the accumulation accuracy due to the film division. Furthermore, in the manufacturing method according to the eighth aspect, since openings are formed on both sides of all the FPC electrodes, high-precision bonding can be performed even when electrode bonding is performed at once for the entire FPC.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electrostatic inkjet head according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a main structure of the inkjet head of FIG.

FIG. 3 is a diagram illustrating the electrostatic inkjet head of FIG. 1;
FIG. 3 is a plan view showing a joint structure between an actuator electrode and an FPC electrode.

FIG. 4 is an enlarged view of a portion A in FIG. 3;

FIG. 5 is an enlarged plan view showing a joint structure between an actuator electrode and an FPC electrode according to a second embodiment of the present invention.

FIG. 6 is an enlarged plan view showing a joint structure between an actuator electrode and an FPC electrode according to a third embodiment of the present invention.

FIG. 7 shows a conventional electrostatic inkjet head.
FIG. 3 is a plan view showing a joint structure between an actuator electrode and an FPC electrode.

FIG. 8 is an enlarged view of a portion B in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 FPC 10a Top part 10b FPC electrode (electrode pattern) 11 Base film 11a 1st division part 11b 2nd division part 21 Slit 22 Opening 23 Opening 51 Electrostatic actuator 51a Step (electrode arrangement part) 51b Actuator electrode 52 Nozzle plate 52a Nozzle Hole 53 driver IC 54 FPC 54b FPC electrode (electrode pattern) 54c base film 55 frame 56 filter 57 joint 61 pressurized liquid chamber 62 diaphragm 62a diaphragm gap sealant 63 nozzle plate sealant 64 fluid resistance 65 common liquid chamber Channel R1 Electrode pattern exposed area R2 Electrode pattern covered area R3 Join area

Claims (8)

[Claims] A plurality of FPCs having a plurality of arranged nozzle holes, a pressurized liquid chamber and an actuator provided corresponding to each of the nozzle holes, and transmitting a drive signal from a head drive circuit to the actuator. Electrode (FPC
Electrodes) are connected to the electrodes (actuator electrodes) of the corresponding actuators, and the actuator electrodes are connected to the FPC electrodes in a state in which a notch is formed in a portion between adjacent FPC electrodes of the FPC base film. An ink jet head, which is joined to the ink jet head. 2. The ink jet head according to claim 1, wherein the notch is a slit formed at an end of an FPC base film. 3. The apparatus according to claim 1, wherein the cutout portion is an opening formed at an end of the FPC base film.
2. The inkjet head according to item 1. 4. A plurality of FPCs having a plurality of arrayed nozzle holes, a pressurized liquid chamber and an actuator provided corresponding to each of the nozzle holes, and transmitting a drive signal from a head drive circuit to the actuator. Electrode (FPC
In the method for manufacturing an ink jet head in which each of the actuator electrodes and the FPC are connected to the corresponding actuator electrode (actuator electrode), a notch is formed at a portion between adjacent FPC electrodes of the FPC base film. A method for manufacturing an ink jet head, wherein the heat bonding with an electrode is separately performed at a different timing for each FPC base film portion divided by the cutout portion. 5. The method for manufacturing an ink jet head according to claim 4, wherein the thermal bonding between the actuator electrode and the FPC electrode is performed by heating only the bonding region. 6. The length of the notch portion is made longer than the joining region between the actuator electrode and the FPC electrode, and the notch is formed so that the joining region is located within the length of the notch portion. The method for manufacturing an ink jet head according to claim 4, wherein a portion is formed. 7. The method according to claim 6, wherein the notch is a slit formed at an end of an FPC base film. 8. The method according to claim 6, wherein the notch is an opening formed at an end of an FPC base film.