JP2004055400A - Connection structure and connection method of flexible flat cable, ink jet head, and ink jet image printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-quality connection structure having a fine pitch at low cost, in a connection structure for respective electrodes of a flexible board and a flexible flat cable. <P>SOLUTION: Solder plating with a thickness of around 1-10 μm is applied to the surfaces of the respective electrodes 2 and 12 of the flexible flat cable 1 and the flexible board 10. Cover resins 3 and 4 of the flat cable 1 are formed of thermoplastic resins, and each have a softening point lower than the melting point of the plated solder. In connection, the respective electrodes 2 and 12 of the flat cable 1 and the flexible board 10 are superimposed on each other, and heated/pressed by a thermocompression tool 20 from the side of a base resin 11 of the flexible board 10 to join the electrodes 2 and 12 to each other by melting the plated solder, and at the same time, the cover resin 3 is melted to weld it to the flexible board 10 so as to cover the circumference of the electrodes 2 and 10. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a connection structure of a flexible flat cable, and a connection method, and more particularly, when connecting the flexible flat cable and each of the flexible electrodes, by soldering the electrodes together, and melting the resin of the flexible flat cable. The present invention relates to a connection structure and a connection method for a flexible flat cable that covers the periphery of each electrode. Further, the present invention relates to an inkjet head using the connection structure and an inkjet printing apparatus equipped with the inkjet head.
[0002]
[Prior art]
As a conventional example of a connection structure between a printed wiring board and each electrode of a flexible flat cable, a connection structure described in JP-A-2002-16336 is known.
The connection structure of this conventional example includes a printed wiring board including a plurality of electrodes arranged and formed along one side of one surface, and a printed wiring board arranged along one side of one surface of a flexible substrate. A flexible printed wiring board comprising a plurality of formed electrodes is held and fixed so that the plurality of electrodes of the printed wiring board and the plurality of electrodes of the flexible printed wiring board are in direct contact with corresponding pressure. An electrical connection structure for electrically connecting, from a plurality of electrode forming portions of the flexible printed wiring board, a back surface of the plurality of electrode forming surfaces of the printed wiring board via one side of the printed wiring board An electrical connection structure having a U-shaped holding and fixing member for holding and fixing the printed wiring board and the flexible printed wiring board at one side thereof by covering the printed wiring board in a U-shape.
[0003]
In general, since a flexible board is expensive, an inexpensive flexible flat cable may be connected to the flexible board for use in extending and leading the wiring. However, in this case, the electrode of the flexible flat cable connected to the flexible substrate is likely to bend because only the electrode at the tip of the conductor protrudes, and may short-circuit with the adjacent electrode during connection. For this reason, an extra cost is required for the reduction of the yield and the management of the tip of the electrode, and the current situation is that it is used only when the electrode pitch is 1 mm or more, so as to prevent short circuit.
[0004]
In this conventional example, the front end of the flexible board is extended and bent to the back at the end of the printed wiring board. However, (1) the joining direction with the printed wiring board is limited, and (2) the flexible board is printed wiring board. In general, an inexpensive flexible flat cable is used for the purpose of drawing out the wiring from the cable.However, the flexible flat cable is manufactured by arranging the wires that will be the electrodes wound on the rolls, sandwiching them with resin, and cutting them. It is difficult to extend the tip without the wire, (3) the workability is inferior due to the work of bending on the back surface of the printed wiring board, and (4) the bending to the back surface is more workable when the connection target is a flexible flexible substrate. There are problems such as inferiority.
[0005]
FIG. 4 is a cross-sectional view showing a connection structure between electrodes of a flexible substrate and a flexible flat cable of a different conventional example.
In the flexible flat cable 1, a plurality of parallel electrodes 2 are sandwiched between cover resins 3 and 4 made of an insulating coating material, and the cover resins 3 and 4 are integrated by heat welding. The flexible substrate 10 has a plurality of conductors printed on a base resin 11 and the surface is covered with a resist 13. The plurality of conductors formed on one surface of the base resin 11 are connected to the electrodes 12 arranged in the side edge direction on the side edge of the base resin 11.
[0006]
When electrically connecting the flexible substrate 10 and the flexible flat cable 1 as described above, the electrodes 12 of the flexible substrate 10 are soldered in advance, and the flexible flat cable 1 exposes only the electrode 2 at the tip of the conductor. The electrode 2 of the flexible flat cable 1 is superimposed on the electrode 12 of the flexible substrate 10 and soldered from the flexible flat cable side using a thermocompression bonding tool 20 such as thermocompression bonding or a soldering iron. A reinforcing and insulating tape (not shown) was stuck on the upper surface.
[0007]
In the case of this method, (1) the electrode 2 of the flexible flat cable 1 is easily bent and a short circuit between adjacent conductors easily occurs. (2) The electrode width and the electrode thickness are increased to prevent the bending of the electrode 2 and the fine pitch is increased. (3) It is necessary to affix a reinforcing and insulating tape after joining, resulting in an increase in cost.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the prior art as described above, and in the electrical connection between a flexible substrate and a flexible flat cable, connection is possible even at a fine pitch of about 0.5 mm pitch. Further, it is an object of the present invention to provide a connection structure and a connection method with a high yield without bending the electrode tip at a low cost.
Another object of the present invention is to provide an ink jet head and an ink jet printing apparatus which employ a fine-pitch high-quality flexible board and a flexible flat cable for electrical connection.
[0009]
[Means for Solving the Problems]
The present invention has been made to achieve the above object, and the invention of claim 1 is a flexible flat cable connection structure for connecting each electrode of a flexible substrate and a flexible flat cable, wherein at least each of the electrodes is provided. One side is subjected to solder plating, and the bottom surface of the electrode of the flexible flat cable opposite to the flexible substrate is attached to a cover resin, and the electrodes of the flexible flat cable and the flexible substrate are overlapped. The electrodes are connected to each other by melting the solder plating by thermocompression bonding from the flexible substrate side, and the molten resin is fused to the flexible substrate by covering the periphery of each electrode by melting the cover resin. It is characterized by doing.
According to a second aspect of the present invention, in the connection structure for a flexible flat cable according to the first aspect, the cover resin is made of polyethylene terephthalate.
According to a third aspect of the present invention, in the flexible flat cable connection structure of the first aspect, a total of solder plating thickness of each electrode of the flexible flat cable and the flexible substrate is 1 to 10 μm.
[0010]
According to a fourth aspect of the present invention, in the flexible flat cable connection structure of the first aspect, a reinforcing plate is provided on an outer surface of a portion of the flexible flat cable to be thermocompression-bonded.
According to a fifth aspect of the present invention, in the connection structure for a flexible flat cable according to the first aspect, the flexible substrate has a thickness of 80 μm or less. According to a sixth aspect of the present invention, in the flexible flat cable connection structure of the first aspect, the solder plating applied to each electrode of the flexible flat cable and the flexible substrate is Sn plating or SnBi plating.
[0011]
The invention according to claim 7 is that at least one electrode of the flexible substrate and the flexible flat cable is subjected to solder plating, the respective electrodes of the flexible flat cable and the flexible substrate are overlapped, and thermocompression bonding is performed from the flexible substrate side. In a method of connecting a flexible flat cable in which the solder plating is melted to connect the electrodes together and a resin cover of the flexible flat cable is welded to the flexible substrate, the thermocompression bonding includes the flexible substrate and the flexible flat cable. It is characterized in that a thermocompression bonding tool is installed inside the overlapping area.
An eighth aspect of the present invention is an inkjet head using the flexible flat cable connection structure of the first to sixth aspects.
According to a ninth aspect of the present invention, there is provided an inkjet printing apparatus including the inkjet head according to the eighth aspect.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples shown in FIGS.
FIG. 1 is a cross-sectional view illustrating a connection structure of electrodes of a flexible substrate and a flexible flat cable according to an embodiment of the present invention.
The flexible flat cable 1 is obtained by sandwiching a plurality of parallel conductors between cover resins 3 and 4 made of an insulating coating material and thermally melting the cover resins 3 and 4 to integrate the conductors. The conductor is a flexible flat cable. One end is formed on the electrode 2.
The flexible substrate 10 has a structure in which a plurality of conductors are formed on the surface of a base resin 11 by printing, and the surface on which the conductors are formed is covered with a resist 13. The ends of the plurality of conductors formed on the surface of the base resin 11 are formed on the electrodes 12 arranged on the side edge of the base resin 11 in the side edge direction. As the base resin 11, a heat-resistant polyimide resin is often used, and the surface of the electrode 12 is generally plated with solder, tin, gold, or the like.
[0013]
In the end structure of the flexible flat cable 1, the one cover resin 3 reaches the electrode 2 at the tip of the conductor of the flexible flat cable 1 and prevents the electrode 2 from breaking apart and shorting between adjacent electrodes. . The other cover resin 4 is terminated before the front end of the electrode 2, and one surface of the electrode 2 is exposed, and serves as a bonding surface with the electrode 12 of the flexible substrate 10.
The surface of the electrode 2 is plated with solder by about 1 to 10 μm.
The cover resins 3 and 4 are made of a thermoplastic resin and have a softening point lower than the melting point of solder plating.
[0014]
In the connection between the electrode 12 of the flexible substrate 10 and the electrode 2 of the flexible flat cable 1, the electrode 2 of the flexible flat cable 1 and the electrode 12 of the flexible substrate 10 are arranged on the base resin 11 side of the flexible substrate 10 so as to face each other. Heat and pressure are applied by the thermocompression bonding tool 20 to melt the solder plating applied to the surfaces of the electrodes 2 and 12 to join the electrodes 2 and 12 together.
At this time, the heat conducted through the base resin 11, the electrode 12, and the electrode 2 also melts the cover resins 3, 4 of the flexible flat cable 1 immediately below and in the vicinity of the thermocompression bonding tool 20, and the molten resins 3a, 4a The flexible substrate 10 is welded so as to cover the periphery of the electrode 12 and the electrode 2. The welding resins 3 a and 4 a reinforce the joint between the electrode 12 and the electrode 2.
[0015]
As the cover resins 3 and 4, a general covering material for a flexible flat cable can be used. However, if the cover resin is formed of polyethylene terephthalate (PET), the polyethylene terephthalate has a low softening point, so that it can be easily welded to a flexible substrate. (Claim 2)
[0016]
The solder plating is desirably applied to both the electrode 2 of the flexible flat cable 1 and the electrode 12 of the flexible substrate 10, but is applied to at least one of the electrodes.
If the thickness of the solder plating applied to the electrode 2 of the flexible flat cable 1 and the electrode 12 of the flexible substrate 10 is extremely thin, the bonding may not be performed sufficiently, and there may be a case where conduction between the electrodes cannot be obtained. Also, while the connection strength is reduced and the solder plating is easily peeled off, if the solder plating thickness is extremely large, the molten solder plating may protrude from the electrode and short-circuit with the adjacent electrode.
Therefore, by setting the total thickness of the solder plating applied to the electrode 2 of the flexible flat cable 1 and the electrode 12 of the flexible substrate 10 to 1 to 10 μm, an open or a short circuit can be prevented. (Claim 3)
[0017]
FIG. 2 is a cross-sectional view illustrating a connection structure of electrodes of a flexible substrate and a flexible flat cable according to another embodiment of the present invention.
The connection structure of the embodiment shown in FIG. 2 is different from the connection structure of the embodiment shown in FIG. 1 in that a reinforcing plate 5 is attached to the back side where the electrode 2 of the flexible flat cable 1 is exposed. .
In the connection structure of the embodiment shown in FIG. 1, the cover resin 3 melted during the thermocompression bonding spreads outside the pressurized portion of the thermocompression bonding tool 20 and adheres to a receiving stand (not shown) of the flexible flat cable, and the thermocompression bonding is repeated. Unnecessary resin accumulates on the cradle, which hinders connection.
Therefore, the reinforcing plate 5 is attached to the back side of the portion where the electrode 2 of the flexible flat cable 1 is exposed, to reduce the adhesion of the molten resin 3a to the pedestal. (Claim 4)
[0018]
Further, since the reinforcing plate 5 reduces heat radiation from the bottom surface of the flexible flat cable 1 to the cradle during thermocompression bonding, a stable connection between the electrodes 2 and 12 and a flexible substrate can be obtained regardless of the properties of the cradle. Welding between 10 and the flexible flat cable 1 is obtained.
Furthermore, after the flexible substrate 10 and the flexible flat cable 1 are connected, the presence of the reinforcing plate 5 makes it difficult for the mechanical stress of the peeling to be directly applied to the connection portion, and the flexible substrate and the flexible flat cable having the peripheral flexibility. And the connecting portion is less likely to break.
[0019]
Further, when the thickness of the flexible substrate 10 is reduced to 80 μm or less, heat is easily transmitted to the cover resin 3 of the flexible flat cable 1 and is easily welded to the flexible substrate 10.
Further, the improvement of the thermal conductivity makes it possible to easily set the heating and pressurizing conditions of the thermocompression bonding tool 20. (Claim 5)
[0020]
The solder plating applied to the electrode 2 of the flexible flat cable 1 and the electrode 12 of the flexible substrate 10 uses general solder, but by using Sn plating without using Pb or SnBi plating, the environment and the human body due to Pb are removed. Adverse effects can be prevented. (Claim 6)
[0021]
When the pressing position of the thermocompression bonding tool 20 is outside the range where the flexible flat cable 1 and the flexible substrate 10 in the direction parallel to the electrodes 2 and 12 of the flexible flat cable 1 and the flexible substrate 10 are outside, The solder plating melts in the direction of the adjacent electrode near the end of the thermocompression bonding tool 20 during thermocompression and tends to flow, and there is a possibility that adjacent electrodes may be short-circuited.
Therefore, by setting the pressing position of the thermocompression bonding tool 20 inside the overlapping margin of the flexible flat cable 1 and the flexible substrate 10, short-circuiting between adjacent electrodes can be prevented. (Claim 7)
[0022]
The connection structure of the flexible flat cable as described above has various uses such as OA devices such as printers and scanners, computer devices, audio / video devices, and robots.
In particular, in an ink jet head, many ejection channels are arranged at minute intervals, and a flexible substrate is often used. However, since it is expensive, it is made as small as possible and inexpensive. However, when wiring the signal lines from the flexible board to the outside, in the method of connecting the protruding electrodes of the flexible flat cable to the flexible board with a soldering iron or the like, the electrode spacing is as large as about 1.0 mm, It is necessary to increase the size of the flexible substrate.
Therefore, by connecting using the connection structure of the flexible flat cable as described above, the wiring can be drawn out without increasing the size of the expensive flexible substrate, so that an inexpensive inkjet head can be provided. (Claim 8)
[0023]
FIG. 3 is a perspective view showing a main part of the ink jet printing apparatus according to the embodiment of the present invention.
3, a sheet feed roller 34 driven by a sheet feed motor 35 is pivotally supported on left and right side plates 32 and 33 of a case 31, and a guide belt 36 is fixed in front of the sheet feed roller 34 in parallel thereto. ing.
A carrier 39 is slidably guided and supported on the guide belt 36, and a recording head is mounted on the carrier 39. The illustrated recording head is an inkjet head 40 having an ink tank, and an ink ejection hole for forming a flying ink droplet is provided on the front surface of the inkjet head 40.
A carrier motor 41 for reciprocating the carrier 39 is mounted on the carrier 39 itself, and moves the carrier 39 along the rack 37 by rotating a pinion 42 meshing with the rack 37.
[0024]
A support roller 43 is provided on a portion of the carrier 39 opposite to the sliding portion with the guide belt 36, and the support roller 43 rolls on a rail 38 laid on the upper surface of the case 31 as the carrier 39 moves. Therefore, the carrier 39 is guided by the guide belt 36 and the rail 38, and can correctly reciprocate in a predetermined posture. In FIG. 3, a control board 44 for controlling the ink jet printing apparatus is mounted on the case 31, and electrical connection between the control board 44 and a head drive circuit on the carrier 39 is performed by a flexible flat cable 45. The connection structure of the flexible flat cable described above can be applied to the connection between the flexible flat cable 45 and the control board 44 and the connection between the flexible flat cable 45 and the carrier 39.
[0025]
In general, the inkjet printing apparatus performs color printing, and includes a plurality of inkjet heads in the inkjet printing apparatus. For this reason, as the size of the flexible substrate increases, the cost increases according to the number of inkjet heads.
Therefore, an inexpensive inkjet printing apparatus can be provided by using an inkjet head using the flexible flat cable connection structure as described above. (Claim 9)
[0026]
【The invention's effect】
As is clear from the above description, the present invention has the following effects.
According to the first aspect of the present invention, in the connection structure of the flexible flat cable for connecting the electrode of the flexible substrate and the electrode of the flexible flat cable, the electrode is plated with solder, and the bottom surface of the electrode is attached to a cover resin. The electrode of the flexible flat cable is overlapped with the electrode of the flexible substrate, and the resin in which the cover resin is fused is formed by thermocompression bonding from the flexible substrate side to melt the solder plating and connect the electrodes. And is welded to the flexible substrate so that a fine-pitch connection structure can be easily and inexpensively provided without any complicated mechanism and structure.
[0027]
According to the second aspect of the present invention, since the cover resin of the flexible flat cable is formed of polyethylene terephthalate (PET), a softening point of the resin cover is low, and the connection structure is easily welded to the flexible substrate and has good workability. Can be.
[0028]
According to the invention of claim 3, since the total of the solder plating thickness applied to the electrode of the flexible flat cable and the solder plating thickness applied to the electrode of the flexible substrate is 1 to 10 μm, openness between the electrodes can be improved. Short circuit between adjacent electrodes can be prevented.
[0029]
According to the fourth aspect of the present invention, since the reinforcing plate is attached to the back surface of the thermocompression bonding portion of the flexible flat cable, the adhesion of the molten resin to the cradle during thermocompression bonding is reduced, and a stable connection is obtained. The stress applied to the part can be reduced.
[0030]
According to the fifth aspect of the present invention, since the thickness of the flexible substrate is 80 μm or less, the thermal conductivity is improved, the cover resin of the flexible flat cable is easily welded, and the heating and pressing conditions of the thermocompression bonding tool are easily set. Can be done.
[0031]
According to the sixth aspect of the present invention, since the solder plating applied to the electrodes of the flexible flat cable and the flexible substrate is Sn plating or SnBi plating, it is possible to prevent Pb from adversely affecting the environment and the human body.
[0032]
According to the invention of claim 7, each electrode of the flexible substrate and the flexible flat cable is plated with solder, and the electrode of the flexible flat cable in which the bottom surface of the electrode to be bonded is attached to the cover resin is connected to the flexible substrate. In the method of connecting a flexible flat cable, the cover plate of the flexible flat cable is welded to the flexible board while the electrodes are connected by melting the solder plating and connecting the electrodes together. Since the thermocompression bonding tool performs thermocompression bonding inside the area where the flexible substrate and the flexible flat cable overlap, the plating on each electrode melts in the direction of the adjacent electrode near the end of the thermocompression bonding tool 20 during thermocompression bonding. Adjacent without flowing It is possible to prevent short-circuiting of the poles.
[0033]
According to the invention of claim 8, since the connection structure between the flexible substrate and the electrodes of the flexible flat cable according to claims 1 to 6 is used for the ink jet head, the wiring can be drawn out without increasing the size of the expensive flexible substrate, so that the cost is reduced. A simple inkjet head can be provided.
[0034]
According to the ninth aspect of the present invention, since the inkjet printing apparatus uses the inkjet head of the eighth aspect, wiring can be drawn out without enlarging an expensive flexible substrate, so that an inexpensive inkjet head can be provided. An ink jet printing apparatus that generally includes a head can also be provided at low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a connection structure of electrodes of a flexible substrate and a flexible flat cable according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a connection structure of electrodes of a flexible board and a flexible flat cable according to different embodiments.
FIG. 3 is a perspective view showing a main part of the ink jet printing apparatus according to the embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a connection structure between electrodes of a conventional flexible substrate and a flexible flat cable.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Flexible flat cable, 2 ... Electrode, 3, 4 ... Cover resin, 3a, 4a ... Molten resin, 5 ... Reinforcement board, 10 ... Flexible board, 11 ... Base resin, 12 ... Electrode, 13 ... Resist, 20 ... Heat Crimping tool, 31 ... case, 32, 33 ... side plate, 34 ... sheet feed roller, 35 ... sheet feed motor, 36 ... guide belt, 37 ... rack, 38 ... rail, 39 ... carrier, 40 ... inkjet head, 41 ... carrier Motor, 42: pinion, 43: support roller, 44: control board, 45: flexible flat cable.

Claims (9)

In the connection structure of the flexible flat cable that connects each electrode of the flexible substrate and the flexible flat cable, at least one of the electrodes is plated with solder, and the other side of the electrode of the flexible flat cable is opposite to the flexible substrate. The bottom surface is attached to a cover resin, the electrodes of the flexible flat cable and the flexible substrate are overlapped, and the electrodes are connected by melting the solder plating by thermocompression bonding from the flexible substrate side, A connection structure for a flexible flat cable, wherein the resin covers the periphery of each of the electrodes and is welded to the flexible substrate by melting the cover resin. The connection structure for a flexible flat cable according to claim 1, wherein the cover resin is made of polyethylene terephthalate. The connection structure for a flexible flat cable according to claim 1, wherein the total solder plating thickness of the flexible flat cable and each electrode of the flexible substrate is 1 to 10 m. 2. The flexible flat cable connection structure according to claim 1, wherein a reinforcing plate is provided on an outer surface of a portion of the flexible flat cable to be thermocompression-bonded. The connection structure for a flexible flat cable according to claim 1, wherein the thickness of the flexible substrate is 80 µm or less. 2. The flexible flat cable connection structure according to claim 1, wherein the solder plating applied to each electrode of the flexible flat cable and the flexible substrate is Sn plating or SnBi plating. Solder plating is applied to at least one electrode of the flexible substrate and the flexible flat cable, each electrode of the flexible flat cable and the flexible substrate is overlapped, thermocompression-bonded from the flexible substrate side, and the solder plating is melted. In the method of connecting a flexible flat cable in which the electrodes are connected to each other and the cover resin of the flexible flat cable is welded to the flexible substrate, the thermocompression bonding is performed by heating the inside of a region where the flexible substrate and the flexible flat cable overlap. A method for connecting a flexible flat cable, which is performed by installing a crimping tool. An ink jet head using the flexible flat cable connection structure according to any one of claims 1 to 6. An inkjet printing apparatus comprising the inkjet head according to claim 8.

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