JPH09300629A - Production of ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the resistance component generated in a common electrode part without damaging the insulating properties between adjacent terminals in a method for connecting an FPC substrate to the substrate terminal of an ink jet head. SOLUTION: In a method for producing an ink jet head by thermally bonding a flexible substrate to an ink jet head having a large number of nozzles and equipped with a large number of pressure generating means for emitting ink droplets from the respective nozzles corresponding to recording content under pressure, a large number of individual terminals connected to one electrodes of the respective pressure generating means and the common terminal 17 connected to the other electrodes thereof in common are formed at mutually approaching positions and the heating quantity or pressure quantity applied to the part of the common terminal 17 after the terminals 102a, 102b of the flexible substrate are positioned on the terminals is set to a value larger than the heating quantity or pressure quantity applied to the parts of the individual terminals to thermally bond both terminals under pressure at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a flexible substrate to terminals of an inkjet head substrate.

[0002]

2. Description of the Related Art As an application example of an electrostatic actuator, it has been proposed that an ink jet head uses a vibrating plate for attracting force due to static electricity.
Japanese Patent No. 9351 discloses such an inkjet head. From page 4, line 14 to page 5, line 11 of JP-A-2-289351, as stated,
This inkjet head has a nozzle, an ink flow path communicating with the nozzle, a vibration plate formed in a part of the flow path,
It has an electrode formed opposite to the diaphragm, and a forward electric pulse is applied between the diaphragm and the electrode to deform the diaphragm by electrostatic force and eject ink droplets from the nozzle. It is the one.

[0003]

By the way, JP-A-2-
As described in Japanese Patent No. 289351, an electric pulse in a quasi-direction is applied between a diaphragm and an electrode formed so as to face the diaphragm so that an electrostatic force generated between the diaphragm and the electrode is applied. In the method of ejecting ink droplets using the above, the displacement speed of the diaphragm when a voltage is applied between the electrodes is determined by the capacitance C and the wiring resistance R of the capacitor composed of the common electrode and each individual electrode.
Governed by a time constant consisting of the product of

In particular, when a large resistance component is generated in the portion connecting the common electrode and the external drive circuit, the voltage applied to each capacitor also changes with the change in the number of nozzles to be driven, and therefore the displacement speed of the diaphragm also. When a large number of nozzles are driven at the same time, the displacement speed for ejecting ink droplets may not be obtained. Therefore, it is necessary to suppress the resistance component on the common electrode side in particular.

On the other hand, an ink jet head using an electrostatic actuator uses silicon as a substrate to form a flow path,
An extremely small and high density inkjet head can be manufactured at low cost by applying a semiconductor process to the electrode wiring. In order to take advantage of these advantages, signals are sent to the inkjet head and power is supplied. It is also necessary to form the terminals for the external drive circuit and the terminals for the external drive circuit with high density.

As a method of connecting the terminals arranged in such a high density, two adherends are thermocompression-bonded by using an anisotropic conductive adhesive to be flexible with the terminals on the electrostatic actuator side. A method of connecting between boards (hereinafter also referred to as FPC, Flexible Print Circuit) is effective, but in the existing method, in order to achieve both conductivity between connecting terminals and insulation performance between adjacent terminals, a common electrode is used. It was difficult to sufficiently suppress the resistance component generated on the side.

The present invention has been made to solve the above problems, and provides a method for connecting an FPC board to a board terminal of an ink jet head so as to satisfy desired characteristics. is there.

[0008]

According to a method of manufacturing an ink jet head of a first aspect of the present invention, a plurality of nozzles are provided, and a plurality of pressure generating means for ejecting ink droplets from the respective nozzles according to recording contents. In a method for manufacturing an ink-jet in which a flexible substrate is thermocompression-bonded to an ink-jet head provided with, a plurality of first terminals connected to one pole of each pressure generating means and the other pole of each pressure generating means are commonly used. The second terminal to be connected is formed at a position close to each other,
A terminal of a flexible substrate having at least two terminals,
After positioning on the first and second terminals respectively, the heating amount applied to the second terminal portion is set to a value larger than the predetermined heating amount applied to the first terminal portion, The feature is that the terminals are pressed simultaneously and thermocompression bonded.

Further, according to the method of manufacturing an ink jet head described in claim 2, the ink jet head has a plurality of nozzles, and a plurality of pressure generating means for ejecting ink droplets from the respective nozzles according to recording contents. In a method of manufacturing an inkjet in which a flexible substrate is thermocompression bonded to a head,
A plurality of first terminals connected to one pole of each pressure generating means and a second terminal commonly connected to the other pole of each pressure generating means are formed at positions close to each other, and at least 2
After positioning the terminals of the flexible substrate having the above terminals on the first and second terminals, respectively, the amount of pressure applied to the second terminal portion is applied to the first terminal portion. It is characterized in that both terminals are thermocompressed at the same time by setting a value larger than a predetermined pressurization amount.

As described above, with respect to the terminals on the individual electrode side, the amount of heat and the amount of pressurization at the time of thermocompression bonding satisfying all of sufficient adhesive strength, conductivity between terminals to be connected, and insulation performance between adjacent terminals. For the terminal on the common electrode side, the amount of heating or the amount of pressurization is set to a larger value than for the individual side, and thermocompression bonding is performed, resulting in the connection part of the terminal on the common electrode side. The resistance component can be reduced. Even in this case, the pitch between the terminals on the common electrode side is sufficiently wider than that on the individual side, so that it is possible to sufficiently maintain the insulation performance from the terminals adjacent to the terminals on the common electrode side.

Further, as described in the invention described in claim 3, by providing the notch between the common terminal and the individual terminal of the flexible substrate, stress is applied to the flexible substrate after thermocompression bonding. Since it does not remain, sufficient connection strength can be obtained.

Further, in order to bond the substrate terminal on the side of the electrostatic actuator and the terminal on the side of the flexible substrate, an adhesive layer made of an anisotropic conductive adhesive is previously formed on the terminal of the flexible substrate. Is desirable.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an ink jet head manufacturing method according to the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view of an ink jet head according to an embodiment of the present invention, which is a partial sectional view. 2 is an enlarged view of part A of FIG. 1, FIG. 3 is a perspective view of the inkjet head of the embodiment of FIG. 1 after assembly, and FIG. 4 is a cross-sectional side view of the inkjet head of the embodiment of FIG. FIG. 5 is a sectional view taken along line AA of FIG. Although the present embodiment shows an example of an edge eject type in which ink droplets are ejected from nozzle holes provided at the end of the substrate, ink droplets are ejected from nozzle holes provided at the upper surface of the substrate. The face eject type may be used.
The inkjet head 10 of the present embodiment has a laminated structure in which three substrates 1, 2 and 3 having the structure described in detail below are stacked and joined.

The intermediate second substrate 2 is a silicon substrate, and a plurality of nozzle grooves 1 are formed on the surface of the substrate 2 in parallel from one end at equal intervals so as to form a plurality of nozzle holes 4.
1 and a recess 12 communicating with each nozzle groove 11 and forming a discharge chamber 6 having a diaphragm 5 as a bottom wall;
2 is a narrow groove 13 provided at the rear part of the second ink inlet
And a recess 14 that will form a common ink cavity 8 for supplying ink to each ejection chamber 6. The ink inlet 13a is provided behind the recess 14.
Is provided, which has a size smaller than the nozzle hole 4 and also functions as a filter for preventing dust in the ink from entering the head. In addition,
The narrow groove 13 will form the orifice 7 when the substrate 2 and the third substrate 3 are joined.

Regarding the provision of the common electrode 17 (second terminal) to the second substrate 2, it is important that the work function of the metal material of the semiconductor and the electrode is large and small. As the electrode material, titanium is used as an undercoat and platinum is used, or chromium is used as an undercoat, and gold is used, but the present invention is not limited to this embodiment, and another combination may be used depending on the characteristics of the semiconductor and the electrode material. . The vibrating plate 5 is formed by doping the second substrate 2 with boron and stopping the etching, and a thin and uniform thickness is obtained.

Further, as shown in FIG. 2, the oxide film 2 having a thickness of about 1 μm is formed on the entire surface of the second substrate 2 excluding the common electrode 17.
4 is formed, which is caused when the vibrating plate 5 comes into contact with an individual electrode 21 described later when the inkjet head is driven,
It functions as an insulating layer to prevent dielectric breakdown and short circuits.

Borosilicate glass is used for the lower first substrate 1 bonded to the lower surface of the second substrate 2, and a vibration chamber 9 is formed on the upper surface of the first substrate 1. A concave portion 15 having an elongated pillar 35 is provided near the center.
If the diaphragm 5 has a large thickness and a predetermined rigidity necessary for ink ejection can be obtained, the column 35 may not be provided. In the present embodiment, the distance between the diaphragm 5 and the individual electrode 21 arranged to face the diaphragm 5 is
That is, the gap maintaining means is provided on the second substrate so that the length G of the gap portion 16 (see FIG. 3, hereinafter referred to as “gap length”) becomes the difference between the depth of the recess 15 and the thickness of the individual electrode 21. Two
It is composed of a vibration chamber recess 15 formed on the upper surface of the. As another example, the recess may be formed on the lower surface of the second substrate 2. Here, the depth of the recess 15 is set to 0.3 μm by etching. The pitch of the nozzle grooves 11 is 0.2 mm and the width thereof is 80 μm.

A vibration chamber 9 is formed by bonding the first substrate 1 to the second substrate 2, and gold is added to each position on the first substrate 1 corresponding to the vibration plate 5. 1
μm is sputtered, and a gold pattern is formed in the same shape as that of the vibrating plate 5 so as to surround the column 35 to form the individual electrode 21. The individual electrode 21 includes a lead portion 22 and a terminal portion 23.
(First terminal). These electrodes, etc.
The material of Nos. 2 and 23 may be an acidic conductive film such as ITO instead of gold.

The upper third substrate 3, which is bonded to the upper surface of the second substrate 2, uses the same borosilicate glass as the first substrate 1. By joining the third substrate 3, the nozzle hole 4, the ejection chamber 6, the orifice 7, and the ink cavity 8 are formed. Then, the convex portion 3 is provided in the ink cavity 8 so as to have strength so that the concave portion is not crushed when the second substrate 2 and the third substrate 3 are joined.
6 are provided.

Next, the first substrate 1 and the second substrate 2 are anodically bonded by applying a temperature of 270 to 400 ° C. and a voltage of 500 to 800 V, and under the same conditions, the second substrate 3 and the third substrate 3 are joined. And are joined together to assemble the inkjet head as shown in FIG. The gap length G formed between the diaphragm 5 and the individual electrode 21 on the second substrate 2 after the anodic bonding is the difference between the depth of the recess 15 and the thickness of the individual electrode 21, as described above,
In this embodiment, the thickness is 0.2 μm.

After the ink jet head is assembled as described above, as shown in FIG. 3 or 4, wiring (F) is provided between the common electrode 17 and the terminal portion 23 of the individual electrode 21.
A drive circuit 102 is connected by a PC (flexible printed circuit) 101.

An anisotropic conductive film is used in the present embodiment as a means for joining the wiring 101 and the electrodes 17 and 23 (details of this point will be described later). Vibration chamber 9
Nitrogen gas is fed into and is hermetically sealed by an insulating sealant 30. In the present embodiment, sealing is performed in the vicinity of the terminal portion 23, and the volume of the actuator includes not only the vibration chamber 9 but also the volume of the groove formed by the lead portion 22.

The ink 103 is supplied to the inside of the first substrate 1 from an ink tank (not shown) via an ink supply pipe 33 and an ink supply container 32 fitted outside the ink jet head, and the ink cavity 8, the ejection chamber 6 and the like. Meets Then, as shown in FIG. 3, the ink in the ejection chamber 6 is repeatedly charged and discharged at a predetermined timing with respect to the electrostatic actuator composed of the diaphragm 5 and the individual electrodes 21 facing the diaphragm 5, so that the diaphragm 5 becomes The ink is vibrated by the electrostatic force generated between the vibrating plate 5 and the individual electrodes, ejected as ink droplets 104 from the nozzle holes 4 of the inkjet head 10 and printed on the recording paper 105.

Next, referring to FIGS. 6 and 7, a preferred embodiment of the terminal connecting device according to the present invention will be described.

FIG. 6 is a schematic view showing an inter-terminal connecting device according to an embodiment of the present invention, in which the terminals 23 formed on the first substrate of the above-mentioned ink jet head 10 and
This is applied to the case where the common electrode 17 formed on the second substrate 2 and the terminals 102a and 102b formed on the FPC are connected. FIG. 7 is a plan view showing the FPC bonded to the inkjet head 10 in FIG.

In the figure, reference numeral 110 denotes an anisotropic conductive adhesive in which conductive particles such as carbon and nickel are dispersed in the adhesive, which is previously applied to the surfaces of the terminals 102a and 102b of the FPC 101 with a predetermined thickness. Has been done.

A heater 202 is inserted inside the first heater block 201 fixed to the first pressure mechanism 204. The thermocouple 203 for temperature control is installed and fixed in the central portion of the heater block 201, is connected to the temperature controller 205, and controls the current value or ON / OFF of the heater 202 according to the set temperature to supply power to the heater 202.
As a result, the heater block 201 is heated to a constant set temperature.

Similarly, the heater 20 is also attached to the first heater block 206 fixed to the second pressurizing mechanism 209.
7, a thermocouple 208 for temperature control is installed and fixed in the central portion of the heater block 209, and is heated to a constant set temperature by the temperature controller 205. The temperatures of the first and second heat blocks and the heating time, the pressures of the first and second pressurizing mechanisms, and the pressurizing time can be set individually.

The terminal connecting device 20 having the above-mentioned structure
The inkjet head 10 is set to 0, and the FPC 101 is set so that the terminal 102a overlaps the first terminal 23 and the terminal 102b overlaps the second terminal 17. At this time, the heat blocks 201 and 207 are in a state of being retracted to a position above the position shown in FIG. 6 so that the inkjet head 10 and the FPC 101 can be easily set.

The position of the FPC with respect to each terminal of the ink jet head 10 is adjusted by using a microscope so that alignment marks (not shown) previously provided on both sides are aligned with each other.

In this embodiment, the depth G of the concave portion of the first substrate 1 on which the terminals 23 are arranged in a row is 0.25 μm.
m, the second substrate has a thickness of 100 μm, and the terminals 17 and 23 have a thickness of 0.1 μm. Therefore, 100.25 is provided between the first terminal 23 and the second terminal 17.
There is a step of μm.

After the ink jet head 10 and the FPC 101 are set in the inter-terminal connection device 200, the temperature and pressure of the heat block 206 applied to the terminals 17, 102b from the control panel (not shown) provided in the inter-terminal connection device. Pressurization amount of mechanism 209, pressurization time, terminals 23, 1
The temperature of the heat block 201 applied to the 02a side, the amount of pressure applied by the pressure mechanism 204, and the pressure time are set. After setting, thermocompression bonding is started by the switch etc. provided on the control panel. When heating of each heater block is started, and the temperature controller detects that the temperature of the heater block has reached the set temperature and is stable, each heater block is pushed down toward the inkjet head 10 by the pressurizing mechanism and set. Pressure is applied to the FPC 101 with a pressurizing amount.

After the set pressurizing time ends, each heat block retreats upward and the thermocompression bonding ends.

In this embodiment, the terminals 23, 10
The heating temperature on the 2a side is 270 ° C, the heating temperature on the terminals 17 and 102b side is 400 ° C, and both terminals have a pressing force of 150 g.
When f was applied and thermocompression bonding was performed for 20 seconds, good results were obtained.

The temperature of the terminals 17 and 102b is set higher than that of the individual side, because the terminals 17 are common electrodes and it is desirable to obtain sufficient conductivity. Further, even in this case, the pitch between the terminals on the common electrode side is sufficiently wider than that on the individual side, so that it is possible to sufficiently maintain the insulation performance from the terminals adjacent to the terminals on the common electrode side. .

On the other hand, the terminals 23 and 102a are individual electrodes arranged in a row at a fine pitch, and if the installation temperature is increased, the insulation between adjacent terminals may not be sufficient, so the set temperature is low. Is set to. For the same reason, it is desirable to set the pressurization amount of the terminals on the fine pitch side to be slightly lower even when it becomes necessary to make a difference in the pressurization amount.

In this way, when there is a step between the terminals even with a slight amount, or when the terminals are thermocompression bonded under different conditions, as shown in FIG.
It is desirable to provide the notch 103 between the terminals of the PC.

As a result, even if the terminals on the common electrode side and the terminals on the individual electrode side are joined with different amounts of heat and pressure,
The stress can be absorbed by the cut portion in the flexible substrate after thermocompression bonding, and sufficient connection strength can be obtained.

As described above, according to the present invention, regarding the terminals on the individual electrode side, thermocompression bonding satisfying all of sufficient adhesive strength, conductivity between terminals to be connected, and insulation performance between adjacent terminals. Set the heating amount and pressurizing amount at the time, and for the common electrode side terminal, set the heating amount or pressurizing amount to a larger value than the individual side and perform thermocompression bonding It is possible to reduce the resistance component generated in the connection portion of the side terminal.

As a result, the change in the voltage applied to each capacitor due to the change in the number of nozzles to be driven can be suppressed small, more nozzles can be driven at the same time, and a higher printing speed can be obtained.

The present invention is not limited to the above-mentioned embodiment, and various modifications can be made.

For example, in the above-described embodiment, the case where the invention is applied to the ink jet head using the electrostatic actuator as the pressure generating means has been described, but the present invention is not limited to this, and the bubble method and the piezo method are used. Even when various print heads such as the above are used, when the terminal resistance on the common electrode side becomes a problem, the same effect can be obtained by applying the manufacturing method of the present invention.

In the above embodiment, the silicon substrate is used as the second substrate, but the present invention is not limited to this, and may be a conductor such as a metal,
It may be an insulator in which electrodes are wired. However, since the surface of the silicon substrate can be finely processed, it is optimal as a substrate for an inkjet head.

[0045]

As described above, according to the first aspect of the present invention, a plurality of nozzles are provided, and a plurality of pressure generating means for ejecting ink droplets from the respective nozzles are provided according to the recording content. In the inkjet manufacturing method in which a flexible substrate is thermocompression-bonded to an inkjet head, the terminals on the individual electrode side all satisfy sufficient adhesive strength, conductivity between connected terminals, and insulation performance between adjacent terminals. The amount of heat applied to the common electrode side is set to a value larger than the amount of heat applied to the individual side, and thermocompression bonding is performed so that the insulation performance from the terminals adjacent to each terminal is not compromised. It is possible to reduce the resistance component generated at the connection portion of the terminals on the common electrode side.

Further, as in the invention described in claim 2, even if the pressurization amount is set to a predetermined value instead of the heating amount,
The same effects as those of the described invention can be obtained.

Further, as described in the invention described in claim 3, by providing the notch between the common terminal and the individual terminal of the flexible substrate, stress is applied to the flexible substrate after thermocompression bonding. Since it does not remain, sufficient connection strength can be obtained.

[Brief description of drawings]

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

FIG. 2 is an enlarged view of a portion A in FIG.

3 is a perspective view of the inkjet head of the embodiment of FIG. 1 after assembly.

4 is a cross-sectional side view of the inkjet head of FIG.

5 is a cross-sectional view taken along the line AA of FIG.

FIG. 6 is a schematic view of an inter-terminal joining device according to an embodiment of the present invention.

FIG. 7 is a plan view of an FPC board according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st board 2 2nd board 3 3rd board 4 Nozzle hole 5 Vibration plate 10 Inkjet head 17 2nd terminal (common terminal) 21 Counter electrode 23 1st terminal (individual terminal) 101 Flexible wiring Substrate (FPC) 102 terminals 200 terminals bonding equipment

Claims (4)

[Claims] 1. A method for manufacturing an ink jet, wherein a flexible substrate is thermocompression-bonded to an ink jet head having a plurality of nozzles and having a plurality of pressure generating means for ejecting ink droplets from the nozzles according to recording contents. In, a plurality of first terminals connected to one pole of each pressure generation means and a second terminal commonly connected to the other pole of each pressure generation means are formed at positions close to each other, and at least The terminals of the flexible substrate having two or more terminals are respectively referred to as the first and second terminals.
After positioning on the terminals, the amount of heat applied to the second terminal portion is set to a value larger than the predetermined amount of heat applied to the first terminal portion, and both terminals are simultaneously pressed to generate heat. A method for manufacturing an inkjet head, which comprises press-bonding. 2. A method of manufacturing an ink jet, wherein a flexible substrate is thermocompression-bonded to an ink jet head having a plurality of nozzles, and a plurality of pressure generating means for ejecting ink droplets from the nozzles according to recording contents. In, a plurality of first terminals connected to one pole of each pressure generation means and a second terminal commonly connected to the other pole of each pressure generation means are formed at positions close to each other, and at least The terminals of the flexible substrate having two or more terminals are respectively referred to as the first and second terminals.
After being positioned on the terminal of the first terminal, the amount of pressure applied to the second terminal portion is set to a value larger than the predetermined amount of pressure applied to the first terminal portion, and both terminals are thermocompression-bonded at the same time. A method for manufacturing an inkjet head, comprising: 3. The method of manufacturing an inkjet head according to claim 1, wherein a cut is provided between the terminals of the flexible substrate. 4. The method of manufacturing an inkjet head according to claim 1, wherein an adhesive layer made of an anisotropic conductive adhesive is formed on the terminals of the flexible substrate. Method.