JP2002216872A - Print head for ink jet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a print head for ink jet having a structure of press-welded FPC board and PCB board, which can prevent conduction failure between electrodes when a FPC board and a PCB board are press welded, and surely press-weld them within a short time, by using a relatively simple split structure of the electrode part of the FPC board print head. SOLUTION: For the print head for ink jet, an electrode part of a FC board is made to have a horizontally split structure in order to release a mismatch of relative position between electrode of the FPC board and a PCB board. And a plurality of electrode parts of the PCB board are made to have a structure having a difference of levels in vertical direction. Further, the level difference of the electrodes of the FPC board are made to have a structure of arranging them in staggered-shape. By those FPC board structure, the conduction failure between the electrodes when the FPC board is press-welded to the PCB board is prevented, and both boards can be surely press-weld within a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet printhead having an FPC board for connecting an electric signal and a PCB board having a function of generating a control signal, for example, applied to a printing unit or an ink-jet printing apparatus. In particular, the present invention relates to an FPC structure that eliminates a relative displacement between electrodes of an FPC board and a PCB board.

[0002]

2. Description of the Related Art In recent years, ink jet print heads have become P
ZT actuator section, PCB board having a function of generating an electric signal for driving the ZT actuator section, and FP connecting both of them
Many products having a C substrate have been commercialized. In these ink jet print heads, a PZT actuator having many fine electrodes is driven by an electric signal from a PCB substrate having many fine electrodes. Patterns and electrodes are formed. Details will be described below.

FIG. 1 shows a conventional FPC board structure used in the present invention, and FIG. 2 shows a corresponding conventional PCB board structure. First, a conventional FPC structure will be described. As shown in FIG. 1, the conventional FPC board 4 has a Cu (18 μm) bus line formed by etching on a polyimide substrate 1 (25 μm). The line is composed of Ni (3 to 9 μm) and Au.
(0.03 to 0.05 μm). Further, a resist is formed on the bus lines other than the electrode section 2 and the electrode section 3 to form an integrated FPC board 4. The electrode section 2 will be described. The central electrode is used as a reference for crimping in order to disperse the elongation of the electrode part 2 to the left and right. Although not shown, this is called a crimping reference. Then, from this crimping standard, the width is 100 μm left and right and the length is 2.7.
256 mm-shaped electrodes are formed at a constant pitch of 180 μm. At this time, the electrode pitch is designed to be as small as possible in order to achieve high-density wiring. The electrode width is designed to be as small as possible in order to minimize the relative displacement between the PCB substrate 7 and the electrode portion 8 shown in FIG. The electrode section 3 will be described. The electrode portion 3 at the other end of the FPC board 4 is pressed against an electrode on the surface of the PZT actuator for an inkjet head. However, the electrode portion 3 is formed as a series of electrode portions instead of a divided structure in which the electrode portion 3 is divided and pressed in sequence due to the restriction of the electrode structure on the surface of the PZT actuator to be crimped.

Next, the conventional PCB substrate 7 will be described with reference to FIG. As shown in FIG.
An electrode pattern of Cu (35 μm) is formed thereon by etching, and this electrode pattern is plated with Au. The electrode section 8 will be described. Electrode part 8
Is used as a reference for crimping. Although not shown, this is called a crimping reference. An electrode having a width of 50 μm and a length of 3.5 mm is arranged at a constant pitch 180
256 pieces are formed at an interval of μm. At this time, the electrode pitch is designed to be as small as possible in order to achieve high-density wiring.

As for the electrode width, the FP shown in FIG.
It is designed to be as large as possible in order to minimize the relative displacement between the C substrate 4 and the electrode portion 2.

Here, the above-mentioned conventional FPC board 4 is susceptible to the ambient environmental temperature and humidity, and particularly when the humidity changes greatly, expansion and contraction occur with the change.
When pressure-bonding to the CB substrate 7, a relative displacement between the electrodes may occur.

The situation will be described below. When the ambient temperature / humidity at the time of crimping is 25 ° C. and 60%, there is no particular problem, but when the ambient temperature / humidity changes to 25 ° C. and about 80% and is maintained for 4 hours or more, the FPC board 4 expands. Occurs.

FIG. 3 is a schematic view of electrode displacement (temperature: 25 ° C., humidity: 80%) when a conventional FPC board structure is used. This figure shows a conventional FPC in an environment with a temperature of 25 ° C and a humidity of 80%.
This schematically shows how much displacement occurs when a plurality of electrodes formed on the electrode portion 2 on the substrate 4 are pressed against a plurality of electrodes formed on the electrode portion 8 on the PCB substrate 7. Things. Although the electrode portion 8 and the electrode portion 2 originally overlap each other, they are shown vertically separated for convenience of explanation. As shown in FIG. 3, when the crimping criterion of the electrode portion 8 and the electrode portion 2 is a crimping criterion 9 and a crimping criterion 5, respectively, the maximum relative positions of the electrodes 51 and 52 located at the ends of the PCB board 7 and the FPC board 4 are shown. Misalignment occurs. Since the external dimensions of the FPC board 4 are designed based on the case where the ambient temperature is 25 ° C. and 60%, the relative positional deviation increases in a humid environment such as 25 ° C. and 80%, and the horizontal electrode Gap 56
Occur about 0.037 mm. When pressure bonding is performed in this state, the protruding amount 72 of the electrode is about 0.012 mm, which causes a problem of poor conduction. In addition, there is a problem that it takes a long time to temporarily fix in the crimping process. However, the conduction failure here means that the protrusion amount 72 of the electrode becomes 0 mm or more.

The calculation result of the electrode displacement amount 56 is shown below.

The longitudinal dimension of the electrode portion of the FPC board 4 is 70 = 92.
Dimensional change rate at 0.025% at 25 ° C. and 80% (see FIG. 4 FIG. 4 showing the relationship between temperature and humidity and FPC board size). Between the electrode 51 and the electrode 52 when the
Is the amount of electrode displacement 56 = (92 mm × 0.08%) / 2 =
0.037 mm.

Conventionally, in order to solve the problem caused by the temperature and humidity, the electrode width of the FPC board electrode portion is designed to be as small as possible with respect to the PCB board electrode width, and the FPC board is determined by the resulting difference in width (allowable dimension). Proposals have been made to absorb the expansion and contraction of.

The allowable dimensions will be described with reference to FIG.

As shown in FIG. 3, assuming that the width of the electrodes formed on the conventional PCB substrate 7 is the electrode width 60 and the width of the electrodes formed on the FPC substrate 4 is the electrode 61, the temperature of the conventional FPC substrate 4 becomes lower. The amount of elongation (allowable dimension) of the FPC board 4 at which the electrodes can overlap each other even if they expand under the influence of humidity
Is expressed as allowable dimension = (electrode width 60/2) − (electrode width 61/2).

In this conventional example, the ambient temperature at the time of pressing the substrate is 0 ° C.
If the humidity is within the range of ± 10% based on the range of 40% to 60%, no inter-electrode conduction failure occurs.

[0015]

However, according to this conventional method, if there is a change in the ambient temperature and humidity at which the expansion of the FPC board exceeds the allowable dimension, the electrodes are not formed when the PCB board and the FPC board are crimped. This causes a relative displacement between them. As a result, poor electrical conduction between the electrodes has occurred, and the efficiency of the pressure bonding operation has been significantly reduced.

In view of such circumstances, the present invention uses a relatively simple structure for dividing an FPC board into an electrode portion.
It is an object of the present invention to provide an ink-jet printhead which prevents poor conduction between electrodes when a substrate is press-bonded to a PCB substrate and which can surely press-bond both in a short time.

[0017]

The actuator of the ink jet print head according to the present invention is made of PZT. The electrodes of the actuator section and the PCB substrate having a function of generating an electric signal for driving the electrodes are formed of an FPC.
In order to eliminate the relative displacement between the electrodes caused by the influence of the surrounding temperature and humidity when the FPC board and the PCB board are pressure-bonded in the ink jet print head having the structure connected by the board, The electrode portion was divided into a plurality of electrode groups in the electrode arrangement direction. Further, the plurality of electrode groups of the FPC board are arranged so as to have a step in a direction perpendicular to the direction in which the electrodes are arranged.
Further, a structure is provided in which the steps of the electrode group of the FPC board are provided in a staggered manner.

According to such an FPC board structure, the FPC
Provided is an ink-jet printhead which prevents poor conduction between electrodes when a substrate is press-bonded to a PCB substrate and which can surely press-bond both in a short time.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents of the present invention will be described below.

FIG. 5 is a first embodiment of the FPC board of the present invention.
FIG. 2 shows an example of an FPC board 15 in which an electrode portion on the side connected to the PCB board is divided into four parts in the horizontal direction. The same components as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. First, FIG. 5 will be described. The FPC board 15 is formed by etching a Cu (18 μm) bus line on a polyimide substrate 1 (25 μm) by etching.
(3 to 9 μm) and Au (0.03 to 0.05 μm). Further, a resist is formed on the bus lines other than the plurality of electrode portions to form an integrated F
A PC board 15 is formed.

Here, the number of divisions of the electrode portion of the FPC board 15 of the present invention will be described with reference to FIG. 3 schematically showing electrode misalignment (temperature: 25 ° C., humidity: 80%) when the conventional FPC board structure is used. As shown in FIG. 3, assuming that the width of the electrodes formed on the conventional PCB substrate 7 is the electrode width 60 and the width of the electrodes formed on the FPC substrate 4 is the electrode 61, the conventional FPC substrate 4 is affected by the temperature and humidity. Limit of length that can be extended by (allowable dimension)
Is the permissible dimension = (electrode width 60/2)-(electrode width 61/2)
It is expressed as This allowable dimension and the conventional FPC board 4 (25
(° C., 60%), the following relationship holds for the electrode portion longitudinal dimension 70.

(Longitudinal dimension 70 of the electrode portion of the conventional FPC board 4)
* 0.08%) / 2 ≤ permissible dimension However, the conventional FP obtained from this formula is that the average change rate of the FPC board at a temperature of 25 ° C and a humidity of 85% is 0.08%.
The electrode section longitudinal dimension 70 of the C substrate 4 (25 ° C., 60%) is 2
The figure shows the maximum electrode part longitudinal dimension value of the FPC board 4 which does not cause the inter-electrode continuity failure even when the FPC board 4 is stretched in an environment of 5 ° C. and 80%.

According to the current specifications, the electrode width 60 = 0.1 mm,
Since the electrode width 61 is 0.05 mm and the electrode part longitudinal dimension 70 of the FPC board 4 is 70 mm, the maximum electrode part longitudinal dimension value of the FPC board 4 allowed at a temperature of 25 ° C. and a humidity of 60% is set in this design dimension. The maximum electrode portion longitudinal dimension value of the FPC board 4 ≤ 62.5 mm.

In the case of the FPC board 15 of the present invention, the design values of the electrode widths are the same as those described above, so that an FPC board (25 ° C., 60
%) Is 62.5 mm. As can be seen from the results, the FPC board 15 of the present invention must be divided so that the dimensions of the individual electrode portions are 62.5 mm or less. The number of divisions reduces the number of steps for temporarily fixing the FPC board. It is desirable to set it to a minimum.

As described above, the following two conditions are considered when determining the number of divisions of the FPC board according to the present invention.

The longitudinal dimension of one of the divided electrode portions satisfies the following expression. (Longitudinal dimension of one divided electrode part * 0.08%) /
2 ≦ Allowable dimension but allowable dimension = (PCB board electrode width /
2)-(FPC board electrode width / 2).

0.08% is the FP used in the present invention.
The FPC dimensional average change rate of the C base material at 25 ° C. and 80% environment. When the FPC base material has another configuration, this value is obtained by an experiment or the like in accordance with each configuration and applied. A base material having a large expansion coefficient has a relationship in which this value increases, but the longitudinal dimension of one of the divided electrode portions decreases accordingly.

It is desirable that the number of divisions be minimized as far as possible.

In the present embodiment, the electrode portion is divided into four parts for the sake of explanation and for convenience of description. In this case, one electrode part length satisfies the condition that it is 23 mm (92 mm / 4).

Next, the details of the four divided electrode portions will be described. The electrode portion at one end of the FPC board 15 which is pressed against the PCB board is formed by a narrow groove from the middle of the polyimide substrate 1, and the electrode portion 11, the electrode portion 12, the electrode portion 13, and the electrode portion 1 are formed.
4 is divided into four. Electrode part 11, electrode part 12,
The width of the elongated groove dividing the electrode portions 13 and 14 was set to a minimum distance such that the divided electrode portions did not overlap with each other during crimping. In this embodiment, the thickness is set to 0.2 mm in consideration of the expansion of the polyimide substrate 1. The length of the elongated groove is set as long as possible so as not to impair the strength of the FPC board 15, and is set to 15 mm in this embodiment. Since the configurations of the electrode unit 11, the electrode unit 12, the electrode unit 13, and the electrode unit 14 are the same, the electrode unit 11 will be described as a representative. The central electrode is used as a reference for crimping in order to disperse the elongation of the electrode portion 11 right and left. Although not shown, this is called a crimping reference. From the crimping reference, 64 electrodes having a width of 100 μm and a length of 2.7 mm are formed on the left and right at intervals of a constant pitch of 180 μm. At this time, the electrode pitch is designed to be as small as possible in order to achieve high-density wiring.

As for the electrode width, the PC shown in FIG.
It is designed to be as small as possible to minimize the relative displacement between the B substrate 7 and the electrode portion 8. With reference to FIG. 8, a description will be given of the relative displacement when the electrodes of the FPC board 15 and the conventional PCB board 7 are crimped together.

FIG. 8 is a schematic diagram of electrode misalignment (temperature: 25 ° C., humidity: 80%) when the FPC board structure of the present invention is used.
This figure shows how much displacement occurs when a plurality of electrodes formed on the electrode portion 11 on the FPC board 15 of the present invention are pressed against a plurality of electrodes formed on the electrode portion 8 on the PCB substrate 7. This is a schematic representation. Although the electrode portion 8 and the electrode portion 11 originally overlap each other, they are shown vertically separated for convenience of explanation. The misalignment of the other divided electrode portions is the same as in the present case, and a description thereof will be omitted.

As shown in FIG. 8, the electrode portions 8 and 1
Assuming that the crimping criterion 1 is the crimping criterion 31 and the crimping criterion 10, respectively, the maximum relative displacement between the electrodes 51 and the electrodes 40 located at the ends of the PCB board 7 and the FPC board 15 is the same as in the related art. However, the length of the electrode portion 11 is one obtained by dividing the electrode portion 2 of the conventional FPC board 4 of FIG.
About / 4. As a result, the PCB substrate 30
And the electrode 51 and the electrode 4 located at the end of the FPC board 15.
The relative displacement of 0 can be reduced to about 1/4. Therefore, even in a humid environment such as a humidity of 80%, the horizontal displacement between the electrodes can be extremely reduced, and the gap 57 between the electrodes can be reduced to about 0.0092 mm. When pressure bonding is performed in this state, no protrusion between the electrodes occurs.

The calculation result of the electrode gap 57 is shown below.

The electrode portion longitudinal dimension 71 of the electrode portion 71 = 92 /
4 = 23 mm Dimensional change rate at 25 ° C. and 80% = 0.08% (Refer to FIG. 4 showing the relationship between the temperature and humidity and the size of the FPC board.) Therefore, from 25 ° C. and 60% to 25 ° C. and 80% % Of the electrode 51 and the electrode 40 when the ratio changes to%, the electrode deviation 57 = (23 mm × 0.08%) / 2 =
0.0092 mm.

According to such an FPC structure, expansion and contraction can be sufficiently absorbed even when the temperature and humidity greatly change during storage or in a pressure bonding environment, and the relative displacement between the electrodes of the FPC board and the PCB board can be eliminated. it can. Further, it is possible to realize an ink-jet print head having an FPC board structure capable of preventing conduction failure between electrodes and reliably performing pressure bonding in a short time.

FIG. 6 is a view showing a second embodiment of the FPC board of the present invention. This figure shows an FPC board 2 in which four electrode portions divided in the first embodiment are arranged with a step in the vertical direction.
1 shows an example. The same components as those in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted. FIG. 6 will be described. Electrode part 1
7. The step of the electrode section 18 is set to a minimum step that does not overlap the electrode section 18 when the FPC pressure head used for the press bonding presses the electrode section 17. This form is 3.0
mm. Step between electrode section 18 and electrode section 19, electrode section 1
The step between the electrode 9 and the electrode section 20 is set in the same manner.
The horizontal spacing between the electrode portions 17 and 18 will be described. The horizontal dividing interval is set so that the interval between the electrode located at the rightmost end of the electrode portion 17 and the electrode located at the leftmost end of the electrode portion 18 is 180 μm, that is, the same electrode pitch as that of the conventional FPC board. It was set. The horizontal intervals between the electrode portions 18 and 19 and between the electrode portions 19 and 20 are set in the same manner. Of course, the outer shapes of the divided portions are set so that they do not overlap with each other during crimping. The outer shape of the FPC board 21 is not limited as illustrated.

FIG. 8 shows the relative positional shift when the electrodes of the FPC board 21 and the conventional PCB board 7 are crimped together.
The description is omitted because it is the same as that shown in FIG.

According to such an FPC structure, expansion and contraction can be sufficiently absorbed even when the temperature and humidity greatly change during storage or in a pressure bonding environment, and the relative displacement between the electrodes of the FPC board and the PCB board can be eliminated. . Further, it is possible to realize an ink-jet print head having an FPC board structure capable of reliably performing pressure bonding in a short time by eliminating conduction failure between electrodes.

Further, if the FPC board 21 is constructed by such means, the electrode portions 17 and 18 of the divided FPC 21
An empty space without FPC base material is always formed on the right side of the electrode section 19 and the electrode section 20. Even if the length of the pressure head used for the pressure bonding is extremely longer than the divided electrode portion 17, the pressure can be easily eliminated by releasing the head into the above-mentioned empty space to eliminate the relative displacement.
A PC structure is provided.

Therefore, it is not necessary to manufacture the pressurizing head exclusively, and cost can be saved.

FIG. 7 is a diagram showing Embodiment 3 of the FPC board of the present invention. FIG. 7 shows an example of an FPC board 27 in which four electrode portions divided in the second embodiment are arranged in a staggered manner in the vertical direction. The same components as those in FIG. 5 are denoted by the same reference numerals and description thereof is omitted. FIG. 7 will be described. The step between the electrode section 23 and the electrode section 24 is set to a minimum step that does not overlap with the electrode section 24 when the FPC pressurizing head presses the electrode section 23. This embodiment is 3.0 mm. Electrode part 24
The step between the electrode section 25 and the step between the electrode section 25 and the electrode section 26 is set in the same manner. On the other hand, the horizontal distance between the electrode unit 23 and the electrode unit 24 will be described. The horizontal division interval is set such that the interval between the electrode located at the rightmost end of the electrode portion 23 and the electrode located at the leftmost end of the electrode portion 24 is 180 μm, that is, the same electrode pitch as that of the conventional FPC board. It was set. The horizontal distance between the electrode part 24 and the electrode part 25 and the horizontal distance between the electrode part 25 and the electrode part 26 are set in the same manner. Of course, the outer shapes of the divided portions are set so that they do not overlap with each other during crimping. This FPC
The outer shape of the substrate 27 is not limited as illustrated.

FIG. 8 shows the relative positional shift when the electrodes of the FPC board 27 and the conventional PCB board 7 are crimped together.
The description is omitted because it is the same as that shown in FIG.

According to such an FPC structure, expansion and contraction can be sufficiently absorbed even when the temperature and humidity greatly change during storage or in a pressure bonding environment, and the relative displacement between the electrodes of the FPC board and the PCB board can be eliminated. it can. Further, it is possible to realize an ink-jet print head having an FPC board structure capable of reliably performing pressure bonding in a short time by eliminating conduction failure between electrodes. Further, if the FPC board 27 is formed by such means, an empty space without FPC base material is always formed on the right or left side of the divided electrode part 23, electrode part 24, electrode part 25, and electrode part 26. . Even if the length of the pressure head used for the pressure bonding is slightly longer than the divided FPC electrode portion 23, the FPC structure is provided which allows the head to be released into this space to easily eliminate the relative displacement and perform the pressure bonding. Is done. Therefore, it is not necessary to manufacture the pressurizing head exclusively, and cost can be saved. Further, if the FPC board 27 is formed by such means, the electrode size 41 (about 12 mm) (see FIG. 6) generated in the second embodiment is reduced to about half the electrode size 42 (6 mm) (see FIG. 7). Thus, it is possible to reduce the area of the electrode portion of the PCB substrate to be pressed. Therefore, the PCB substrate can be effectively used.

In the ink jet print head manufactured using the above-described FPC board, the rate of occurrence of inter-electrode conduction failure due to relative positional deviation between the electrodes is 0%. In addition, the time required for the pressure bonding step at that time was reduced to about 1/2 as compared with the case where a conventional FPC board was used. Manufacturing costs were also reduced.

In the above description, the embodiments have been described in order for each embodiment, but the present invention also includes a configuration using three types of combinations among the two types.

[0047]

According to the present invention, there is provided an ink-jet printhead having a structure in which an electrode of an actuator portion of an ink-jet printhead and a PCB substrate having a function of generating an electric signal for driving the same are connected by an FPC substrate. The ambient temperature when crimping the PCB board,
The relative positional deviation between the two electrodes caused by the influence of humidity can be eliminated with a relatively simple FPC electrode part division structure. Further, it is possible to realize an ink jet print head having an FPC board structure capable of preventing poor conduction between electrodes and reliably performing pressure bonding in a short time.

[Brief description of the drawings]

FIG. 1 is a structural view of a conventional FPC board

FIG. 2 is a structural diagram of a conventional PCB substrate.

FIG. 3 is a schematic diagram of electrode displacement when a conventional FPC board structure is used (25 ° C., 80%).

FIG. 4 is a diagram showing a relationship between temperature and humidity and dimensions of an FPC board;

FIG. 5 is a diagram showing a first embodiment of the FPC board of the present invention.

FIG. 6 is a view showing an FPC board according to a second embodiment of the present invention;

FIG. 7 is a diagram showing a third embodiment of the FPC board of the present invention.

FIG. 8 is a schematic view of electrode displacement when the FPC board structure of the present invention is used (25 ° C., 80%).

[Explanation of symbols]

1 ····· Polyimide substrate 2, 3, 8, 11, 12, 13, 14, 17, 18, 1
9, 20, 23, 24, 25, 26 ... electrode part 4, 15, 21, 27 ... FPC board 5, 9, 10, 31 ... crimping standard 6 ... · Glass epoxy base material · · · · · · PCB substrate 40, 51, 52 · · · Electrodes 41, 42 · · · · Electrode dimensions 56, 57 · · · · The amount of electrode misalignment 60, 61 · · · · Electrode width 70, 71 ····· Electrode section longitudinal dimension 72 ··· Electrode protrusion

Continued on front page F term (reference) 5E077 BB31 BB32 BB38 CC06 DD14 HH08 HH10 JJ11 JJ18 JJ30 5E317 AA04 AA07 BB03 GG03 GG14 GG20 5E344 AA01 AA22 BB02 BB04 CC03 CC05 CC07 CC17 CC23 DD10 EE16 EE23

Claims (3)

[Claims] 1. An ink jet print head comprising a PZT actuator section, a PCB board for generating an electric signal for driving the PZT actuator section, and an FPC board for connecting both of the PZT actuator section, wherein each of the FPC boards has a plurality of electrodes. Are arranged, one of which is connected to the PZT actuator, and the other of which is divided into a plurality of electrode groups in the direction in which the electrodes are arranged, and is crimped to the PCB substrate. A printhead for inkjet printing, characterized in that: 2. The ink jet print head according to claim 1, wherein the plurality of electrode groups are arranged with a step in a direction orthogonal to an arrangement direction of the electrodes. 3. The ink-jet printhead according to claim 2, wherein the electrode groups are arranged in a staggered manner.