JP5196303B2 - Connection part structure of flexible printed circuit board and flexible flat cable, liquid droplet ejection head and image recording apparatus using the same - Google Patents

Description

  The present invention relates to an FPC that is a flexible printed circuit board in which circuit components are formed on an insulating film on which a wiring pattern is formed, and a flexible flat cable that transmits various signals supplied from the apparatus side to the FPC on which the wiring pattern is formed. The present invention relates to a connection structure, a droplet discharge head using the connection structure, and an image recording apparatus.

  In general, a printer, a fax machine, a copier, a plotter, or a device that combines a plurality of these functions includes, for example, a droplet discharge head that discharges ink droplets. Some ink jets of black, cyan, magenta, yellow, etc. are ejected and adhered to a recording medium to form a color image. As this droplet discharge head, at least a part of wall surfaces of a plurality of individual liquid chambers individually arranged corresponding to a plurality of parallel nozzles that discharge ink droplets is formed by a diaphragm, and this diaphragm is There is known a piezoelectric liquid droplet ejection head that ejects ink droplets by changing the volume of a liquid chamber by being deformed by a piezoelectric element. The piezoelectric element that discharges the ink droplets is mechanically deformed according to a predetermined driving voltage supplied from a driving driver IC to generate pressure in the individual liquid chamber, and is generated by the main board on the main body side. Is given to a driver IC for driving on an FPC which is a flexible printed circuit board via a flexible flat cable, and detailed control is performed by the driver IC for driving.

  The FPC is a flexible substrate in which a plurality of wirings are provided on one side or both sides of an insulating film. In addition, by using a flexible flat cable to transmit drive waveforms and control signals generated on the FPC and main body side, it is possible to increase the degree of mounting freedom when mounting a droplet discharge head on an inkjet recording apparatus. In addition, there is an advantage that the ink jet recording apparatus can be downsized. In recent years, a COF (chip on film) in which a driver IC for driving is directly mounted on an FPC has been put into practical use, and this technology can shorten the distance from the driver IC to the piezoelectric element. This has the effect of reducing the attenuation and delay of the drive waveform for driving the element, making it possible to drive the piezoelectric element with high efficiency.

  Further, the COP can be mounted on the ink jet recording apparatus in a bent state, and the entire ink jet recording apparatus main body can be downsized, which has the advantage of increasing the degree of freedom in designing the apparatus. However, since the driver IC for driving is joined to the wiring of the insulating film of the COF by soldering and the FPC and the flexible flat cable are also electrically joined by soldering, the head mounting process is performed on the insulating film. When a load due to handling is applied, stress due to the load during handling is applied to the solder joint, and the pattern of the connection portion between the FPC and the flexible flat cable may be disconnected.

In order to prevent disconnection of the circuit pattern, the flexible circuit board shown in Patent Document 1 is reinforced by attaching a flexible resin thin film to the back surface of the connection portion where the circuit pattern is exposed. . Moreover, the flexible substrate shown in Patent Document 2 is provided with a band-shaped metal plate for shape retention when the substrate is bent on the same surface as the surface of the flexible substrate on which the circuit conductor is provided, and the shape to be bent is designated. And measures against disconnection. Moreover, the flexible printed wiring board shown in Patent Document 3 is provided with a slit in the vicinity of the electronic component mounting portion, and bending stress applied to the electronic component mounting portion by bending at an easily bent portion other than the electronic component mounting portion. Try to decrease.
Japanese Utility Model Publication No. 58-116270 Japanese Utility Model Publication No. 52-058757 JP 2006-140416 A

  However, the structures shown in Patent Document 1 and Patent Document 2 are intended to increase the strength of the wiring of the flexible substrate itself, and increase the strength of the connecting portion when another component is connected to the flexible substrate. The circuit pattern in the vicinity of the connection portion may be disconnected. In addition, the flexible printed wiring board disclosed in Patent Document 3 is provided with a portion that is easily bent other than the electronic component mounting portion in order to reduce bending stress applied to the electronic component mounting portion. There is a possibility that the circuit pattern in the vicinity of the connection portion is disconnected. If the circuit pattern in the vicinity of the connection portion is thus disconnected, the device itself does not operate normally.

  The present invention eliminates such problems and adds bending stress in the vicinity of the connection portion of the flexible printed circuit board on which electronic components are mounted and a flexible flat cable that transmits signals including various control signals from the apparatus main body side. However, the connection structure between the flexible printed circuit board and the flexible flat cable, which can surely prevent the circuit pattern in the vicinity of the connection portion from being broken and can prevent a short circuit due to the adhesion of the conductive material, and a droplet discharge head using the same An object of the present invention is to provide an image recording apparatus.

The connection structure of the flexible printed circuit board and the flexible flat cable according to the present invention includes a flexible printed circuit board comprising an electrode pattern formed on a flexible insulating base film, and a flexible flat cable on the surface of the flexible printed circuit board having the electrode pattern. In the connection structure in which the electrode patterns between the two are connected by solder bonding, the connection portion connected by solder bonding between the flexible printed circuit board and the flexible flat cable is exposed from one end in the longitudinal direction of the flexible flat cable. The region including the exposed portion of the electrode pattern and the exposed end surface of the solder joint adjacent to the exposed portion of the electrode pattern, and the other end of the connecting portion between the flexible printed circuit board and the flexible flat cable are opposite to each other. And a region in which a surface of the side opposed to the peripheral portion of said other, and covered with an insulating film, characterized by being reinforced with the one end and the other end portion.

Further, one end of the connecting portion, characterized in that an end portion of the flexible printed circuit board.

  Further, the flexible flat cable has a reinforcing member on a surface opposite to the surface on which the electrode pattern is formed, and the insulating film is attached to a surface opposite to the reinforcing member. .

The insulating film has an alignment hole corresponding to a reference hole for attachment provided in the flexible printed board, and the reference hole for attachment of the flexible printed board and the alignment hole of the insulating film coincide with each other. The insulating film is aligned and affixed to.

  Further, the insulating film has a convex shape.

  Furthermore, the insulating film is formed in a plurality of layers, and at least one layer is formed of a flame retardant material.

  In addition, at least one of the plurality of layers of the insulating film is a moisture-impermeable layer.

  Further, the outermost layer opposite to the adhesive layer of the insulating film is coated with a charging layer.

  A droplet discharge head according to the present invention is characterized by having a connection structure of any one of the flexible printed circuit boards and the flexible flat cable.

  The image recording apparatus according to the present invention includes the droplet discharge head.

The present invention relates to an exposed portion of an electrode pattern exposed from one end in a longitudinal direction of the flexible flat cable of a connecting portion connected by solder bonding between a flexible printed circuit board and a flexible flat cable, and adjacent to the exposed portion of the electrode pattern. A region including the exposed end surface of the solder joint portion to be performed, and a region opposite to the other end portion of the connection portion between the flexible printed circuit board and the flexible flat cable and facing the other end portion, and Is coated with an insulating film to reinforce the one end and the other end , so there is no need to change the design as a measure against pattern breakage of an expensive flexible printed circuit board, and the insulating film has a simple shape. Can be used to reduce the pattern breakage of the flexible printed circuit board.

Further, an insulating film is used to form a region including the exposed portion of the electrode pattern exposed from one end portion of the connecting portion in the longitudinal direction of the flexible flat cable and the exposed end surface of the solder joint adjacent to the exposed portion of the electrode pattern. Since it coat | covers , it can prevent that a dust and water | moisture content adhere to the electrode pattern exposed from an edge part, or a solder joint part, and short-circuit.

Furthermore, by aligning one end of the connecting portion covered by the insulating film with the end of the flexible printed circuit board, the insulating film can be accurately positioned, and the electrode pattern of the flexible printed circuit board can be reliably protected. it can.

  The flexible flat cable has a reinforcing member on the surface opposite to the surface on which the electrode pattern is formed, and the electrode pattern on the flexible printed circuit board is reinforced by attaching an insulating film to the surface opposite to the reinforcing member. It can be reinforced more reliably by being sandwiched between the member and the insulating film.

  In addition, the insulating film is provided with an alignment hole corresponding to the reference hole for attachment provided in the flexible printed circuit board, and the insulation film is aligned so that the reference hole for application of the flexible printed circuit board and the alignment hole of the insulation film coincide. Thus, the insulating film can be positioned more accurately, and the electrode pattern of the flexible printed board can be reinforced reliably.

  Furthermore, the entire surface of the flexible printed circuit board and the flexible flat cable can be reinforced by making the shape of the insulating film convex according to the flexible printed circuit board and the flexible flat cable, thereby further reinforcing the electrode pattern of the flexible printed circuit board. Can be strong.

  Further, by forming the insulating film in a plurality of layers and forming one layer with a flame retardant material, it is possible to improve safety and cope with application of a high voltage.

  Moreover, by making one layer of the plurality of layers of the insulating film into a moisture-impermeable layer, moisture resistance can be improved and safety can be improved. In addition, by coating the charging layer on the outermost layer on the side opposite to the adhesive layer of the insulating film, it is possible to reduce adhesion of dust and moisture floating on the electrode pattern and the solder joint of the flexible printed circuit board.

  The droplet discharge head having the connection structure of the flexible printed circuit board and the flexible flat cable can prevent the electrode pattern of the flexible printed circuit board from being disconnected at the time of assembly, and can discharge the droplet with stable characteristics.

  In addition, by using this droplet discharge head in an image recording apparatus, it is possible to stably form good quality images by stably discharging ink droplets without being affected by ink mist during ink droplet discharge. it can.

  FIG. 1 is a configuration diagram of an ink jet recording apparatus according to the present invention. As shown in the figure, the ink jet recording apparatus 1 has four ink cartridges 2 each containing ink of each color of cyan C, magenta M, yellow Y, and black Bk, and a plurality of nozzles. Recording paper is printed from four droplet discharge heads 3 to which ink is supplied, a carriage 4 on which the ink cartridge 2 and the liquid discharge head 3 are mounted, and paper feed trays 5a and 5b containing the recording paper and a manual feed table 6. A conveyance unit 8 that conveys the image to the unit 7 and a discharge roller 10 that discharges the printed recording paper to the discharge tray 9 are provided. When the image data sent from the host device is printed on the recording paper, the droplet discharge head 3 is applied to the recording paper sent to the printing unit 7 by the transport unit 8 while scanning the carriage 4 along the carriage guide roller 11. Ink is ejected from the nozzles in accordance with the image data to record characters and images.

  As shown in the exploded perspective view of FIG. 2, the droplet discharge head 3 includes a nozzle plate 13 provided with a plurality of nozzles 12, an electrostatic actuator 14, a flexible printed circuit board (FPC) 15, and a flexible flat. A cable (FFC) 16, a frame 17, a filter 18 and a joint portion 19 are provided. The electrostatic actuator 14 includes a pressurized liquid chamber 20 and a fluid resistance path (not shown) provided for each bit, and a common liquid chamber 21 that supplies ink to the pressurized liquid chamber 20 through each fluid resistance path. The nozzle plate 13 made of Ni electroforming or stainless steel is aligned and joined. The pressurizing liquid chamber 19 of the electrostatic actuator 14 has a diaphragm and individual electrodes provided at a predetermined interval with respect to the diaphragm. A voltage is applied between the diaphragm and the individual electrodes to apply positive or negative. Then, the vibration plate is electrostatically attracted or repelled to the individual electrode side to deform it, and the ink in the pressurized liquid chamber 20 is ejected from the nozzle 12 to print on the recording paper. A driver IC 22 is mounted on the FPC 15 and is electrically connected to the electrostatic actuator 14. The frame 17 to which the filter 18 is thermally welded and the joint portion 19 for supplying ink from the ink supply tank or ink cartridge are joined by an adhesive, and the frame 17 is aligned with the nozzle plate 13 joined to the electrostatic actuator 14. Are joined.

  As shown in the top view of FIG. 3A, the FFC 16 has a plurality of FPC-side electrode terminals 23 connected to the electrode terminals for electrical connection of the FPC 15 at one end, and the other end has And a plurality of body-side electrode terminals 24 connected to the body side of the inkjet recording apparatus 1. The FPC-side electrode terminal 23 is connected to a plurality of electrode terminals connected to the driver IC 22 of the FPC 15 as shown in the cross-sectional view showing the connection state in FIG. Various control signals necessary for printing are input from the main body side to the FPC 15 equipped with a driver IC 22 for discharging from the main body 12. The control signal input to the driver IC 22 can eject ink by being divided in time in addition to ejecting ink from all the nozzles 12 simultaneously. That is, if ink is ejected from all the nozzles 12 at the same time, there are disadvantages such as a reduction in recording quality due to the influence of crosstalk between the nozzles 12 and a large amount of power due to temporarily requiring a large current. Although this may occur, these disadvantages can be avoided by time-division driving.

  As the material of the FFC 16, an insulating material that is a flame-retardant resin is used, and the FPC side electrode terminal 23 and the main body side electrode terminal 24 are formed of a plating material, and tin is used as the plating material. The use of tin as a plating material in this way is prohibited by the RoHS Directive (European Environmental Regulations), which will be enforced in Europe from July 2007, but it is used for connectors for electrical connections. Lead is raised as one of the prohibited substances. Therefore, lead cannot be used in the electrical connection portion, and tin is used as a plating material in order to perform lead-free plating.

  As shown in the cross-sectional view of FIG. 3B, the FFC 16 is formed such that the thickness t1 of the FPC side electrode terminal 23 and the thickness t2 of the main body side electrode terminal 24 are different from each other. t <b> 1 is formed larger than the thickness t <b> 2 of the main body side electrode terminal 24. Reinforcing plates 25 are respectively provided on the surfaces of the FFC 16 opposite to the FPC side electrode terminals 23 and the body side electrode terminals 24. When connecting to the electrode terminals of the FPC 15 and the body side, the FPC side Heat is applied to the plating materials for the electrode terminals 23 and the body-side electrode terminals 24 so as to be electrically connected by thermal fusion.

  The reason why the thickness t1 of the FPC side electrode terminal 23 and the thickness t2 of the main body side electrode terminal 24 are made different in this way is to increase the connection strength. In order to increase the connection strength, the thickness t1 of the FPC side electrode terminal 23 and the thickness t2 of the main body side electrode terminal 24 may be increased. However, the thickness t1 of the FPC side electrode terminal 23 and the main body side electrode terminal When the thickness t2 of 24 is increased, it is necessary to take a whisker suppression measure. That is, if tin is used as the plating material for the FPC side electrode terminal 23 and the main body side electrode terminal 24 of the FFC 16 and tin is used for the electrode terminal for electrical connection of the FPC 15, there is a risk of whisker generation. It is known that this whisker has a high probability of occurrence in the case of joining the same metal and can suppress the whisker by reducing the tin content. In order to suppress the occurrence of this whisker, the tin plating thickness t1 of the FPC side electrode terminal 23 of the FFC 16 and the tin plating thickness t2 of the main body side electrode terminal 24 are reduced to 1 to 4 μm, and the thickness of the FPC side electrode terminal 23 is reduced. The thickness t1 and the thickness t2 of the main body side electrode terminal 24 are made different.

  As a method of making the thickness t1 of the FPC side electrode terminal 23 different from the thickness t2 of the main body side electrode terminal 24, in the actual plating process, the plating thicknesses of the FPC side electrode terminal 23 and the main body side electrode terminal 24 are set at a single step. Since it is impossible to make different plating thicknesses in step 1, first, both ends of the FFC 16 are performed with a plating thickness t2 of about 1 μm as the base plating, and further, plating at the end of the FFC 16 that performs electrical connection on the connection side with the FPC 15 In order to increase the thickness, additional plating is performed again only on one side, and the plating thickness t1 is adjusted to a thickness of 1.5 to 4 μm to adjust the main body side electrode terminal 24 with the plating thickness t2 and the FPC side electrode terminal 23 with the plating thickness t1. Form.

  Thus, the connection strength with the electrode terminal of the FPC 15 can be increased by setting the plating thickness t1 of the FPC side electrode terminal 23 to 1.5 to 4 μm. Further, it is possible to suppress the influence on adjacent electrode terminals and the generation of whiskers due to the plating material melted at the time of heat fusion, and it is possible to realize a good electrical connection.

  The electrical connection portion between the FFC 16 and the FPC 15 is a portion that transmits signals necessary for various ejections in the inkjet recording apparatus 1. If the connection resistance value increases, the signals are attenuated and stable ejection cannot be performed. . Therefore, the plating thickness t1 of the FPC-side electrode terminal 23 of the FFC 16 is changed to 2 μm, 3 μm, and 4 μm and joined to the electrode terminal of the FPC 15 to examine the change in contact resistance. As a result, the difference in the plating thickness t1 has a large connection resistance value. There was no change, and the actual connection resistance value was about 0.2Ω, so there was no problem.

  The FPC-side electrode terminal 23 of the FFC 16 in which the FPC-side electrode terminal 23 and the body-side electrode terminal 24 are formed in this way is bonded by being thermally fused to the electrode terminal 26 of the FPC 15 as shown in the sectional view of FIG. . When this FPC-side electrode terminal 23 is heat-sealed to the electrode terminal 26 of the FPC 15, there may be a problem such as a short circuit between adjacent electrode terminals due to the melted plating material, but flame retardant as a material of the FFC 16 Since an insulating material that is a resin is used, a part of the insulating material that is a flame retardant resin of the FFC 16 is melted together with the plating material at the time of heat-sealing, and a molten resin layer 27 of the flame retardant resin is provided between the electrode terminals. Enters and insulates between the electrode terminals. Therefore, when the FPC-side electrode terminal 23 of the FPC 16 is heat-sealed to the electrode terminal 26 of the FPC 15, it is possible to prevent the electrode terminals from being short-circuited by the molten plating material, and the FFC 16 can be stably connected to the FPC 15. In addition, it is possible to stably transmit signals necessary for various ejections to the droplet ejection head 3 to stably eject ink droplets, and to stably form high-quality images with the inkjet recording apparatus 1. Can do.

  Further, by increasing the plating thickness of the FPC side electrode terminal 23 of the FFC 16, excess solder flows out when the FFC 16 and the FPC 15 are joined, and becomes a solder ball and remains on the FPC 15. When head mounting is performed in the next process in this state, force is applied to the joint portion by handling in the mounting process. As a result, pattern disconnection occurs in the FPC pattern of the joint, and there may be a problem in the output image depending on the disconnected pattern.

  Therefore, a functional insulating film 28 having a convex multilayer structure as shown in the top view of FIG. 5 is used as a reinforcing member, and this insulating film 28 is used as an electrode terminal of the FPC 15 as shown in a side sectional view of FIG. Attached so as to cover the exposed end of the electrode terminal 26 on the surface opposite to that of the FPC 15, that is, the surface opposite to the component mounting surface of the FPC 15. The insulating film 28 is formed in a convex shape because the width of the FFC 16 is smaller than the width of the FPC 15 so as to match the shapes of the FFC 16 and the FPC 15. As shown in the cross-sectional view of FIG. 7, the insulating film 28 is formed by laminating a polyethylene terephthalate (PET) layer 29 and an acrylic resin layer 30 that are tough, excellent in heat resistance, and have low water absorption, and is formed on the outer surface of the PET layer 29. The charging layer 31 is coated, and an adhesive seal 32 is provided on the outer surface of the acrylic resin layer 30. The adhesive seal 32 is formed by covering with a release paper 33.

  When the insulating film 28 is attached to the joint between the FPC 15 and the FFC 16, the release paper 33 is peeled off from the insulating film 28 and attached with an adhesive seal 32. Thus, since the insulating film 28 is affixed with the adhesive seal | sticker 32, the insulating film 28 can be made to adhere | attach completely on a junction part and can be reinforced.

  Further, by reinforcing the joint portion between the FFC 16 and the FPC 15 with the insulating film 28, the FPC pattern at the joint portion can form a highly reliable joint portion without causing disconnection. Further, since the exposed portion of the end portion of the electrode terminal 26 of the FPC 15 is covered with an insulating film 28 and sealed, the ink mist adheres to the electrode portion even for the problem of ink mist peculiar to the ink jet recording apparatus 1. This can prevent the short circuit due to the ink mist of the electrode terminal 26 of the FPC 15. Further, the insulating film 28 is a completely separate component from the FPC 15 and has an advantage that the component mounting area of the FPC 15 can be widened by being attached to the surface opposite to the component mounting surface of the FPC 15.

  The position where the insulating film 28 is pasted, particularly the position of the edge, is a very important issue. However, the shape is examined at the design stage, and the foot portion of the component mounted by soldering on the FPC 15 (disconnection) It is necessary to make it a shape that avoids the part that is likely to occur, and to place it at an accurate position. Therefore, the FPC 15 is provided with two sticking reference holes 34 as shown in FIG. 5, and the insulating film 28 is provided with an alignment hole 35 corresponding to the sticking reference hole 34 of the FPC 15 as shown in FIG. The insulating film 28 can be disposed at a predetermined position by providing and attaching the insulating film 28 so that the reference hole 34 for attaching the FPC 15 and the alignment hole 35 of the insulating film 28 coincide with each other.

  Furthermore, the bonding strength between the FPC 15 and the FFC 16 can be further increased by attaching the insulating film 28 to the FPC 15 and the FFC 16 in a convex shape as shown in FIG.

  Further, in consideration of component tolerance at the shape design stage of the insulating film 28, a shape that completely covers the entire surfaces of the FPC 15 and the FFC 16 is impossible, and therefore, several electrodes may be exposed at both ends of the joint portion. . However, by coating the outermost layer of the insulating film 28 with the charging layer 31 for adsorbing the ink mist, the ink mist flying in the vicinity thereof is forcibly absorbed and the ink to the exposed electrode part is absorbed. Mist adhesion can be reduced.

  In the above description, the FPC 15 in which the driver IC 22 that drives the electrostatic actuator 14 of the ink jet recording apparatus 1 is mounted and the FFC 16 that connects the main body side are described. However, an image forming apparatus such as an electrophotographic copying machine, various electrical devices, The present invention can be similarly applied to a flexible flat cable for connecting electrical equipment of a mechanical device.

It is a block diagram of the inkjet recording device of this invention. It is a disassembled perspective view which shows the structure of a droplet discharge head. It is a block diagram which shows the electrode terminal of FFC. It is a layout diagram showing the connection state of the FPC and FFC. It is a top view which shows the state which joined the electrode terminal of FPC and FFC by heat sealing | fusion. It is side surface sectional drawing which shows the state which reinforced the junction part of FPC and FFC with the insulating film. It is sectional drawing which shows the structure of the insulating film which is a reinforcement member.

Explanation of symbols

1; inkjet recording apparatus; 2; ink cartridge; 3; droplet discharge head;
4; carriage, 5; paper feed tray, 6; manual feed table, 7; printing unit, 8;
9; discharge tray, 10; discharge roller, 11; carriage guide roller,
12; Nozzle, 13; Nozzle plate, 14; Electrostatic actuator,
15; flexible printed circuit board (FPC), 16; flexible flat cable (FFC),
17; Frame, 18; Filter, 19; Joint part, 20; Pressurized liquid chamber,
21; Common liquid chamber, 22; Driver IC, 23; FPC side electrode terminal,
24; body side electrode terminal, 25; reinforcing plate, 26; electrode terminal, 27; molten resin layer,
28; insulating film, 29; PET layer, 30; acrylic resin layer, 31; charged layer,
32; Adhesive seal, 33; Release paper, 34; Reference hole for application, 35;

Claims (8)

Connection structure for connecting a flexible printed circuit board made of the electrode pattern formed on a flexible insulating base film, the electrode pattern between the solder joint between the flexible flat cable to a surface having an electrode pattern of the flexible printed circuit board In
The exposed portion of the electrode pattern exposed from one end in the longitudinal direction of the flexible flat cable of the connecting portion connected by soldering the flexible printed circuit board and the flexible flat cable, and the solder adjacent to the exposed portion of the electrode pattern A region including the exposed end surface of the joint portion, and a region opposite to the other end portion of the connection portion between the flexible printed circuit board and the flexible flat cable and facing the other end portion; A flexible printed circuit board-flexible flat cable connection structure characterized in that the one end and the other end are reinforced by covering with an insulating film. The connection structure of the flexible printed circuit board and the flexible flat cable according to claim 1, wherein one end of the connection part is an end of the flexible printed circuit board.   The flexible flat cable has a reinforcing member on a surface opposite to a surface on which an electrode pattern is formed, and the insulating film is attached to a surface opposite to the reinforcing member. The connection structure of the flexible printed circuit board of 1 or 2, and a flexible flat cable.   The insulating film has an alignment hole corresponding to a reference hole for attachment provided in the flexible printed board, and the reference hole for attachment of the flexible printed board and the alignment hole of the insulating film coincide with each other. The connecting structure for a flexible printed circuit board and a flexible flat cable according to any one of claims 1 to 3, wherein the insulating film is aligned and pasted. The connection structure of the flexible printed circuit board and the flexible flat cable according to any one of claims 1 to 4, wherein the insulating film has a convex shape . Adhesive layer opposite the flexible printed circuit board and the connection structure of the flexible flat cable according to any one of claims 1 to 5 charge layer in the outermost layer is characterized in that it is coated in the prior Symbol insulating film.   A droplet discharge head comprising the connection structure of the flexible printed circuit board and the flexible flat cable according to claim 1.   An image recording apparatus comprising the droplet discharge head according to claim 7.

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