Film-like circuit and method for connecting printed circuit board and film-like circuit

Abstract

To accurately align a film circuit with two printed circuit boards when the film circuit for connecting wires of the two printed circuit board is warped.SOLUTION: A film-like circuit (40) for connecting wirings of two printed circuit boards includes a wiring section (43) that is formed of a conductive material and has connection portions (43a) arranged to be nearer to both ends in a predetermined direction, and an insulating section (41) that is formed of an insulating material in a film-like shape and covers the wiring section so as to expose the connection side of each connection section. The film-like circuit is warped such that the connection sides of the connection portions are arranged on the inside and the connection portions near both ends in the predetermined direction approach each other, and at least two through-holes (46, 47) that pass through a center (C1) in a predetermined direction and are spaced apart from each other are formed in a portion of the insulating section where the insulating section does not overlap with the wiring section.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a film-like circuit such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable). [Background technology]

[0002] For example, there is an FFC in which a plurality of conductors arranged in parallel in the conductor width direction are integrated by adhesively covering them with an insulating film in the conductor thickness direction, and exposed portions are formed at both ends of the conductor in the longitudinal direction where the conductors are exposed from the insulating film, and these exposed portions are connected to electrodes provided on a printed circuit board (PCB) (see Patent Document 1). The FFC described in Patent Document 1 has a positioning conductor, and the end exposed from the insulating film is bent so as to protrude from the plane on which the plurality of conductors are arranged in parallel, and a fitting portion that fits into a hole in the printed circuit board is provided between the bent position of the end and the tip of the end. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-49297 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the electrodes (wiring) of the two printed circuit boards are connected by an FFC (film-like circuit). In such a structure, if the FFC is warped, it is difficult to fit the fitting parts of the positioning conductors into the holes in both printed circuit boards, that is, to accurately align the FFC with both printed circuit boards. In particular, when the printed circuit boards and the film-like circuit are automatically aligned by a device, it is even more difficult to accurately align the film-like circuit with both printed circuit boards.

[0005] The present invention has been made to solve these problems, and its main objective is to accurately align a film circuit connecting the wiring of two printed circuit boards with both printed circuit boards when the film circuit is warped. [Means for solving the problem]

[0006] The first means for solving the above problem is A film-like circuit that connects the wiring of two printed circuit boards, a wiring portion formed of a conductive material and having connection portions near both ends in a predetermined direction; an insulating portion formed in a film shape from an insulating material and covering the wiring portion so as to expose a connection side of each of the connection portions; the film-shaped circuit is warped so that the connection sides of the connection parts are inward and the connection parts near both ends in the predetermined direction approach each other, At least two through holes are formed in the insulating portion in a portion not overlapping with the wiring portion, the through holes passing through the center in the predetermined direction and spaced apart from each other.

[0007] According to the above configuration, the film-shaped circuit connects the wiring of two printed circuit boards. The film-shaped circuit includes a wiring section formed of a conductive material and having connection sections near both ends in a predetermined direction, and an insulating section formed in a film shape from an insulating material and covering the wiring section so as to expose the connection sides of the connection sections. Therefore, the wiring of the two printed circuit boards can be connected by connecting the connection sides of the connection sections exposed from the insulating section to the wiring of the two printed circuit boards. When connecting, it is necessary to accurately align the film-shaped circuit with both printed circuit boards.

[0008] In this regard, at least two through holes spaced apart from each other are formed in the insulating portion in a portion that does not overlap with the wiring portion. Therefore, for example, when two printed circuit boards are fixed to a positioning jig having a positioning pin, the film circuit can be aligned with respect to both printed circuit boards by inserting the positioning pin into the through hole of the insulating portion of the film circuit. Furthermore, by inserting the positioning pin into each of at least two through holes spaced apart from each other, the rotation of the film circuit with respect to both printed circuit boards can be restricted. Therefore, the connection portions near both ends of the wiring portion can be accurately aligned with respect to the wiring of both printed circuit boards.

[0009] When connecting, the film circuit and the positioning pin can be brought close to each other so that the positioning pin is inserted from the surface of the connection side of the connection part in the film circuit. Here, warping may occur in the film circuit due to the asymmetry of the configuration in the thickness direction of the film circuit. The film circuit is warped so that the connection side of the connection part is on the inside and the connection parts near both ends in the predetermined direction approach each other. In contrast, the inventor of the present application has focused on the fact that the strength of the part in the insulating part where the through hole is formed is lower than that of the other parts, so that the film circuit is likely to warp from the through hole as a starting point. That is, by adjusting the position where the through hole is formed in the insulating part, the warping of the film circuit can be controlled with high reproducibility. At least two through holes spaced apart from each other pass through the center in the predetermined direction in the insulating part. This allows the film circuit to be warped so that the range including the center in the predetermined direction in the film circuit becomes the apex. For this reason, when a force is applied pressing the film circuit and the positioning pin with the positioning pin and the through hole of the insulating part being slightly misaligned, the film circuit is automatically guided by the warp so that the positioning pin approaches the center in the specified direction. Therefore, even when the printed circuit board and the film circuit are automatically aligned by a device, the film circuit can be accurately aligned with both printed circuit boards.

[0010] In the second embodiment, the through holes are formed at both ends of the insulating part in a direction perpendicular to the predetermined direction. With this configuration, the starting points for warping of the film-shaped circuit can be formed at both ends of the insulating part in a direction perpendicular to the predetermined direction. This makes it easier to warp the entire film-shaped circuit so that the apex is in a range including the center in the predetermined direction.

[0011] In a third aspect, the through hole is formed in a circular shape, and the center of the through hole is located at the center of the insulating part in the predetermined direction. With this configuration, it is easy to warp the entire film circuit so that the center in the predetermined direction becomes the apex.

[0012] The fourth means includes reinforcing terminals formed of a conductive material with a width wider than that of the wiring portion and arranged at both ends of the film-shaped circuit in a direction perpendicular to the specified direction and at both ends of the film-shaped circuit in the specified direction, and the through holes are formed at both ends of the insulating portion in a direction perpendicular to the specified direction and between the reinforcing terminals.

[0013] According to the above configuration, the reinforcing terminals are formed of a conductive material with a width wider than the width of the wiring portion, and are disposed on both ends of the film-like circuit in a direction perpendicular to the predetermined direction and on both ends of the film-like circuit in the predetermined direction. Therefore, by forming connected terminals on the printed circuit board at positions corresponding to the reinforcing terminals of the film-like circuit and connecting the connected terminals of the printed circuit board and the reinforcing terminals of the film-like circuit, the connection strength between the printed circuit board and the film-like circuit can be improved.

[0014] The through holes are formed at both ends of the insulating part in a direction perpendicular to the predetermined direction and between the reinforcing terminals. Therefore, the through holes can be formed by utilizing the portions of the insulating part that do not overlap with the reinforcing terminals at both ends in a direction perpendicular to the predetermined direction. Therefore, in the film circuit in which the reinforcing terminals and the through holes are formed, it is possible to prevent the length of the film circuit in the direction perpendicular to the predetermined direction from becoming long.

[0015] In a fifth aspect, the through holes formed at both ends of the insulating part in a direction perpendicular to the predetermined direction are different in size. With this configuration, it is possible to prevent the film circuit from being oriented in the wrong direction when connecting the film circuit to two printed circuit boards.

[0016] The sixth measure is: A method for connecting the film circuit according to the first aspect and the two printed circuit boards, comprising: Fixing the two printed circuit boards to a positioning jig having at least two positioning pins; a step of bringing the film-like circuit and the positioning pin closer to each other so that the positioning pin is inserted into the through hole from the connection side surface of the connection portion in the film-like circuit; and guiding the film circuit by warping so that the positioning pin approaches the center in the predetermined direction.

[0017] According to the above process, the two printed circuit boards are fixed to a positioning jig having at least two positioning pins. Therefore, the positions of the two printed circuit boards can be aligned with respect to the positioning jig. Then, the film circuit and the positioning pin are brought close to each other so that the positioning pin is inserted into the through hole from the connection side surface of the connection part in the film circuit. Here, the film circuit is warped so that the connection side of the connection part is on the inside and the connection parts near both ends in the predetermined direction approach each other. And, at least two through holes spaced apart from each other pass through the center in the predetermined direction in the insulating part. Therefore, when a force is applied to press the film circuit and the positioning pin with the positioning pin and the through hole of the insulating part being slightly misaligned, the film circuit is automatically guided by the warping so that the positioning pin approaches the center in the predetermined direction. Therefore, even when the printed circuit board and the film circuit are automatically aligned by a device, the film circuit can be accurately aligned with respect to both printed circuit boards.

[0018] Specifically, as in the seventh means, the positioning jig includes a first fixing part for fixing one of the two printed circuit boards and a second fixing part for fixing the other of the two printed circuit boards, the positioning pin is disposed between the first fixing part and the second fixing part, and the method includes a step of fixing one of the two printed circuit boards to the first fixing part and fixing the other of the two printed circuit boards to the second fixing part. According to such a step, the film-like circuit can be easily aligned with respect to the one printed circuit board fixed to the first fixing part and the other printed circuit board fixed to the second fixing part.

[0019] In an eighth method, the film-like circuit is formed of a conductive material with a width wider than the width of the wiring portion, and is provided with reinforcing terminals arranged at both ends of the film-like circuit in a direction perpendicular to the specified direction and at both ends of the specified direction, the reinforcing terminals including a first positioning mark, and on the two printed circuit boards, connected terminals are respectively formed of a conductive material at positions corresponding to the reinforcing terminals of the film-like circuit, the connected terminals including a second positioning mark corresponding to the first positioning mark, and the method includes a step of aligning the first positioning mark with the second positioning mark when the positioning pin is inserted into the through hole.

[0020] According to the above process, the first positioning mark and the second positioning mark are aligned with each other when the positioning pin is inserted into the through hole, and therefore, after the film circuit is aligned with respect to both printed circuit boards by the positioning pin, the position of the film circuit with respect to the printed circuit boards can be fine-tuned using the first positioning mark and the second positioning mark.

[0021] Furthermore, since the first positioning mark is included in the reinforcing terminal of the film-like circuit, the first positioning mark can be formed at the same time when the reinforcing terminal is formed on the film-like circuit. Moreover, since the second positioning mark is included in the connected terminal of the printed circuit board, the second positioning mark can be formed at the same time when the connected terminal is formed on the printed circuit board. Moreover, by connecting the connected terminal of the printed circuit board and the reinforcing terminal of the film-like circuit, the connection strength between the printed circuit board and the film-like circuit can be improved.

[0022] In a ninth method, wiring is formed from a conductive material on each of the two printed circuit boards at a position corresponding to the connection portion of the film-like circuit, and the method includes a step of using a heater tool to press and heat the connection portion and reinforcing terminal of the film-like circuit to connect the wiring of the printed circuit board to the connection side of the connection portion of the film-like circuit, while simultaneously connecting the connected terminal of the printed circuit board to the reinforcing terminal of the film-like circuit.

[0023] According to the above process, the connection portion and the reinforcing terminal of the film-shaped circuit are pressed together and heated by a heater tool, so that the wiring of the printed circuit board and the connection side of the connection portion of the film-shaped circuit are connected, and at the same time, the connected terminal of the printed circuit board and the reinforcing terminal of the film-shaped circuit are connected. Therefore, the connection between the printed circuit board and the film-shaped circuit can be efficiently performed. Furthermore, since the through hole is formed in a part of the insulating part that does not overlap with the wiring portion, even if the heat of the heater tool is transmitted along the wiring portion, the through hole can be prevented from being deformed by heat. Therefore, when the wiring of the printed circuit board and the connection side of the connection portion of the film-shaped circuit are connected by the heater tool, the film-shaped circuit can be prevented from being misaligned with respect to the printed circuit board on the opposite side to the heater tool. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram showing how to connect the wiring of a printed circuit board and the wiring of an FFC. [Diagram 2] FIG. 4 is a plan view showing two printed circuit boards and a positioning jig. [Diagram 3] FIG. 2 is a plan view showing how two printed circuit boards and an FFC are aligned. [Figure 4] FIG. 13 is a partial side view showing two printed circuit boards and an FFC aligned by positioning pins. [Diagram 5] (a) Plan view of the FFC, (b) side view of the FFC. [Figure 6]FIG. 2 is a schematic diagram showing how the FFC is guided by its warpage. [Figure 7] 13 is a plan view showing how the blank portion of the reinforcing terminal and the circular portion of the connection terminal are aligned. FIG. [Figure 8] 13 is an enlarged plan view showing how the blank portion of the reinforcing terminal and the circular portion of the connection terminal are aligned. FIG. [Figure 9] 13 is a diagram showing how the wiring connection portions and reinforcing terminals of the FFC are pressed and heated by a heat tool. [Figure 10] FIG. 1 is a schematic diagram showing how the connection parts of the wiring on the printed circuit board and the wiring on the FFC are connected by a heat tool. [Figure 11] FIG. 1 is a schematic diagram showing an embodiment in which two printed circuit boards and an FFC are mounted on a PLC. [Figure 12] (a) Plan view of a modified FFC, (b) side view of a modified FFC. [Figure 13] (a) Plan view of another modified example of the FFC, (b) Side view of another modified example of the FFC. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment embodied in a printed circuit board and an FFC mounted on a PLC (Programmable Logic Controller) will be described with reference to the drawings.

[0026] As shown in FIG. 1, the printed circuit board 10 includes a substrate 11, an internal pattern portion 12, wiring 13, an insulating layer 14, solder 15, and the like. The substrate 11 is formed in a rectangular plate shape from, for example, epoxy resin, and the like. The internal pattern portion 12 is configured by alternately laminating circuit patterns formed from a conductive material and insulating layers formed from an insulating material. The internal pattern portion 12 is covered with an insulating layer 14. A plurality of wirings 13 are formed on (outside of) the insulating layer 14 from a conductive material (for example, copper) (exposed from the insulating layer 14). Solder 15 is provided on (outside of) each wiring 13. Note that the solder 15 may be omitted, and the plurality of wirings 13 may be exposed on the surface of the printed circuit board 10. Similarly to the printed circuit board 10, the printed circuit board 20 (see FIG. 2) also includes a substrate 11, an internal pattern portion 12, wiring 13, an insulating layer 14, solder 15, and the like.

[0027] The FFC 40 (film-shaped circuit) includes wiring 43, adhesive 42, insulating portion 41, solder 45, etc. The wirings 43 are linearly formed from a conductive material (e.g., copper). The wirings 43 are arranged in parallel (in parallel) to form a plane, and insulating portions 41 are attached to both sides of the wirings 43 by adhesive 42. The insulating portion 41 is formed in a film shape from a flexible and insulating material such as polyimide. The adhesive 42 is, for example, an insulating adhesive such as an epoxy adhesive. The wirings 43 are covered (covered) by the insulating portion 41 except for the connection side (one side) of the connection portion 43a. That is, the insulating portion 41 exposes the connection side of the connection portion 43a. The connection portion 43a is provided at both ends of the linear wiring 43 (closer to both ends in a predetermined direction of the wiring 43). Solder 45 is provided below (on the connection side) of the connection portion 43a. The connection portion 43a may be provided slightly inside both ends of the linear wiring 43. A plurality of wires 43 constitute a wiring section.

[0028] The connection between the printed circuit board 10 and the FFC 40 is generally performed as follows. The positions of the wirings 13 of the printed circuit board 10 corresponding to the solder 15 are preheated from the side opposite to the solder 15 by a heater tool H1 of a preheater. Then, with the solder 15 of each wiring 13 of the printed circuit board 10 and the solder 45 of the connection portion 43a of each wiring 43 of the FFC 40 aligned, the FFC 40 is thermocompression bonded to the printed circuit board 10 by a heater tool H2 of a heater. As a result, the solder 15 of each wiring 13 of the printed circuit board 10 and the solder 45 of the connection portion 43a of each wiring 43 of the FFC 40 are melted and connected. Thereafter, in the same manner, with the solder 15 of each wiring 13 of the printed circuit board 20 aligned and the solder 45 of the connection portion 43a of each wiring 43 of the FFC 40 aligned, the FFC 40 is thermocompression bonded to the printed circuit board 20 by a heater tool H2 of a heater. As a result, the solder 15 of each of the wires 13 of the printed circuit board 20 and the solder 45 of the connection portions 43a of each of the wires 43 of the FFC 40 are melted and connected.

[0029] 2 is a plan view showing the two printed circuit boards 10, 20 and the positioning jig 90. The positioning jig 90 includes a first fixing portion 91, a second fixing portion 92, a pin support portion 95, positioning pins 96, 97, and the like.

[0030] The first fixing portion 91 is formed in a shape corresponding to the printed circuit board 10, and is capable of positioning and fixing the printed circuit board 10. For example, a plurality of positioning holes (not shown) are formed in the printed circuit board 10, and the first fixing portion 91 is provided with insertion pins (not shown) that can be inserted into the positioning holes of the printed circuit board 10. The insertion pins of the first fixing portion 91 are inserted into the plurality of positioning holes of the printed circuit board 10, respectively, to position and fix the printed circuit board 10 to the first fixing portion 91. The second fixing portion 92 is formed in the same manner as the first fixing portion 91, and is capable of positioning and fixing the printed circuit board 20. In a state in which the printed circuit board 10 is fixed to the first fixing portion 91 and the printed circuit board 20 is fixed to the second fixing portion 92, the edge portion of the printed circuit board 10 on which the solder 15 is provided faces the edge portion of the printed circuit board 20 on which the solder 15 is provided.

[0031] The pin support portion 95 is disposed between the first fixing portion 91 and the second fixing portion 92 in the positioning jig 90. The pin support portion 95 supports positioning pins 96 and 97. As shown in the partial side view of FIG. 4, the positioning pins 96 and 97 (only the positioning pin 96 is shown in FIG. 4) extend vertically upward from the pin support portion 95. The positioning pins 96 and 97 are each formed in a cylindrical shape and have a tapered tip. The diameter of the positioning pin 96 is larger than the diameter of the positioning pin 97. The positioning pins 96 and 97 are disposed between the first fixing portion 91 and the second fixing portion 92. In a state in which the printed circuit board 10 is fixed to the first fixing portion 91 and the printed circuit board 20 is fixed to the second fixing portion 92, the positioning pins 96 and 97 are disposed between the printed circuit board 10 and the printed circuit board 20.

[0032] Suction holes 26 are formed in the printed circuit board 20 at positions closer to the printed circuit board 10 than the solder 15. A vacuum pump (not shown) is connected to the suction holes 26 via an intake pipe. When the vacuum pump is driven, negative pressure is supplied to the suction holes 26 via the intake pipe.

[0033] Fig. 3 is a plan view showing the alignment of two printed circuit boards 10, 20 and FFC 40. Note that Fig. 3 shows a state in which wiring 43 and reinforcing terminals 48 are visible through film-like insulating portion 41. Fig. 4 is a partial side view showing the alignment of two printed circuit boards 10, 20 and FFC 40 by positioning pins 96, 97.

[0034] The FFC 40 has through holes 46, 47 formed at positions corresponding to the positioning pins 96, 97. The through holes 46, 47 are formed with shapes and sizes corresponding to the positioning pins 96, 97. Specifically, the diameters of the through holes 46, 47 are set to be equal to or slightly larger than the outer diameters of the positioning pins 96, 97. The positioning pins 96, 97 are inserted into the through holes 46, 47 from the surface 40a on the connection side (solder 45 side) of the connection portion 43a in the FFC 40. This aligns the position of the FFC 40 with respect to the positioning pins 96, 97, and therefore the position of the FFC 40 with respect to the printed circuit boards 10, 20 fixed to the fixing portions 91, 92, respectively.

[0035] Fig. 5(a) is a plan view of the FFC 40, and Fig. 5(b) is a side view of the FFC 40. Note that Fig. 5(a) shows a state in which the wiring 43 and the reinforcing terminals 48 are visible through the film-like insulating part 41.

[0036] The insulating section 41 (and thus the FFC 40) is formed in a rectangular film shape. Each of the wirings 43 extends linearly in the short-side direction (predetermined direction) of the insulating section 41 and the FFC 40. The wirings 43 are arranged in the longitudinal direction (direction perpendicular to the predetermined direction) of the insulating section 41 and the FFC 40. The through holes 46 and 47 are formed in portions of the insulating section 41 that do not overlap with the wirings 43, specifically, at both ends in the longitudinal direction. The through holes 46 and 47 are formed in a circular shape. The diameter of the through hole 46 is larger than the diameter of the through hole 47. That is, the through holes 46 and 47 are different in size from each other. The centers 46a and 47a of the through holes 46 and 47 are located on (at the center of) the center line C1 in the short-side direction of the insulating section 41 and the FFC 40. That is, in a portion of the insulating portion 41 that does not overlap with the wiring 43, at least two through holes are formed that pass through the center of the insulating portion 41 in the short side direction and are spaced apart from each other in the long side direction of the insulating portion 41.

[0037] The FFC 40 includes reinforcing terminals 48 formed of a conductive material (e.g., copper). The reinforcing terminals 48 are formed with a width greater than that of the wiring 43, and are disposed at the four corners of the surface 40a on the connection side (the side on which the solder 45 is exposed) of the connection portion 43a, i.e., at both ends in the longitudinal direction and both ends in the lateral direction. The reinforcing terminals 48 are also provided with solder 45. The through holes 46, 47 are formed at both ends in the longitudinal direction of the insulating portion 41 and between the reinforcing terminals 48. That is, in the longitudinal direction of the insulating portion 41, the positions of the through holes 46, 47 and the position of the reinforcing terminals 48 are the same (approximately the same) (not shifted).

[0038] 7, the reinforcing terminal 48 is formed in a groove shape (U-shape). The reinforcing terminal 48 has a bottom 48a and two legs 48c. The widths of the bottom 48a and the legs 48c are wider than the width of the wiring 43. A blank portion 48b is formed at each of both ends in the longitudinal direction of the bottom 48a. The blank portion 48b (first positioning mark) is formed in a circular shape by a portion without conductive material.

[0039] In the printed circuit boards 10 and 20, the connected terminals 18 are formed of a conductive material (e.g., copper) at positions corresponding to the reinforcing terminals 48 of the FFC 40 (see FIG. 2). As shown in FIG. 7, the connected terminals 18 are formed in a groove shape (U-shape). The connected terminals 18 have a bottom 18a and two legs 18c. The widths of the bottom 18a and the legs 18c are wider than the width of the wiring 13. A blank portion 18b is formed at each of both ends in the longitudinal direction of the bottom 18a. The blank portion 18b is formed in a circular shape by a portion without conductive material. The diameter of the blank portion 18b of the connected terminal 18 is larger than the diameter of the blank portion 48b of the reinforcing terminal 48. Inside the blank portion 18b, a circular portion 18d (second positioning mark) is formed of a conductive material. The center of the blank portion 18b and the center of the circular portion 18d are aligned. The diameter of the circular portion 18d is smaller than the diameter of the blank portion 48b. The distance between the centers of the two blank portions 48b in one reinforcing terminal 48 is equal to the distance between the centers of the two circular portions 18d in one connected terminal 18. Note that the connected terminal 18 may also be provided with solder 15.

[0040] The cross-sectional structure of the FFC 40 is as shown in FIG. 1. The FFC 40 is warped due to the asymmetry of the configuration in the thickness direction of the FFC 40. Specifically, the FFC 40 is warped so that the connection side (surface 40a) of the connection portion 43a faces inward, and the solder 45 (connection portion 43a) at both ends in the short direction approach each other. If the through holes 46, 47 were not formed in the FFC 40, the warping of the FFC 40 would not be constant. For example, the FFC 40 warps so that both ends in the long direction approach each other, or reinforcing terminals 48 at diagonal positions approach each other. Also, the larger the FFC 40, the greater the effect of the warping.

[0041] In response to this, the inventors of the present application have focused on the fact that the strength of the portion of the insulating portion 41 where the through hole is formed is lower than that of the other portion, and therefore the FFC 40 is more likely to warp from the through hole as a starting point. That is, by adjusting the position where the through hole is formed in the insulating portion 41, the warping of the FFC 40 can be controlled with high reproducibility even if the FFC 40 is made larger. Here, the through holes 46, 47 spaced apart from each other in the longitudinal direction of the insulating portion 41 pass through the center of the short side of the insulating portion 41. This allows the FFC 40 to be warped so that the range including the center of the short side of the FFC 40 becomes the apex. Furthermore, the through holes 46, 47 are formed at both ends of the insulating portion 41 in the longitudinal direction. This allows the starting point when the FFC 40 warps to be formed at both ends of the insulating portion 41 in the longitudinal direction. This makes it easier to warp the entire FFC 40 so that the range including the center of the short side becomes the apex. In addition, the centers 46a, 47a of the through holes 46, 47 are located at the center in the short-side direction of the insulating part 41. This makes it easier to warp the entire FFC 40 so that the center in the short-side direction becomes the apex.

[0042] The printed circuit boards 10 and 20 having the above-described configuration are connected to the FFC 40 as follows. The following steps may be performed automatically by a device or manually by an operator.

[0043] 2, the printed circuit board 10 is fixed to a first fixing portion 91 of a positioning jig 90, and the printed circuit board 20 is fixed to a second fixing portion 92. That is, the two printed circuit boards 10 and 20 are fixed to the positioning jig 90 having two positioning pins 96 and 97.

[0044] 6A, the FFC 40 is brought closer to the positioning pins 96, 97 so that the positioning pins 96, 97 (only the positioning pin 96 is shown) are inserted into the through holes 46, 47 (only the through hole 46 is shown) from the surface 40a on the connection side of the connection portion 43a of the FFC 40. At this time, a default position (initial position, standard position) of the FFC 40 with respect to the printed circuit boards 10, 20 is set, and the FFC 40 is brought closer to the positioning pins 96, 97 from this default position. The default position is set so that the position of the FFC 40 matches with the printed circuit boards 10, 20, but the positions of the FFCs 40 placed at the default positions may vary. Alternatively, when the FFC 40 is brought closer to the positioning pins 96, 97 from the default position, the positions of the through holes 46, 47 of the FFC 40 may deviate from the positions of the positioning pins 96, 97. Since the FFC 40 is not warped in the longitudinal direction, the positions of the positioning pins 96, 97 and the positions of the through holes 46, 47 of the FFC 40 are unlikely to deviate from each other in the longitudinal direction of the FFC 40.

[0045] 6(b), when the FFC 40 is brought even closer to the positioning pins 96, 97, the tips of the positioning pins 96, 97 come into contact with the surface 40a of the connection side of the connection portion 43a in the FFC 40. Then, with the tips of the positioning pins 96, 97 slightly misaligned with the through holes 46, 47, a force is applied to press the surface 40a of the FFC 40 against the tips of the positioning pins 96, 97. Note that the force to press the surface 40a of the FFC 40 against the tips of the positioning pins 96, 97 may be applied by an arm of a device holding the FFC 40, may be applied manually by an operator, or may be applied by gravity.

[0046] The FFC 40 is warped so that the center in the short side direction (left-right direction in FIG. 6) is the apex. Therefore, due to the force pressing the surface 40a of the FFC 40 against the tips of the positioning pins 96, 97, the FFC 40 slides relative to the positioning pins 96, 97 so that the positioning pins 96, 97 approach the center in the short side direction, as shown in FIG. 6(c). In other words, the FFC 40 is automatically guided by the warp so that the positioning pins 96, 97 approach the center in the short side direction.

[0047] Next, when the ends of the through holes 46, 47 reach the tips of the positioning pins 96, 97, the positioning pins 96, 97 are inserted into the through holes 46, 47, respectively, as shown in Fig. 6(d). That is, the position of the FFC 40 is aligned with the positioning pins 96, 97, and therefore with respect to the printed circuit boards 10, 20. In this state, the position of the FFC 40 is fixed with respect to the printed circuit boards 10, 20 at two points, the through holes 46, 47, of the FFC 40, so that rotation of the FFC 40 with respect to the printed circuit boards 10, 20 is restricted.

[0048] Next, the positions of the wirings 13 of the printed circuit board 10 corresponding to the solder 15 are preheated from the side opposite to the solder 15 by the heater tool H1 of the preheater.

[0049] Next, in a state where the positioning pins 96, 97 are inserted into the through holes 46, 47, respectively, the positions of the four blanks 48b in the two reinforcing terminals 48 on the printed circuit board 10 side of the FFC 40 are aligned with the four circular parts 18d in the two connected terminals 18 on the printed circuit board 10, respectively, as shown in FIG. 7. Specifically, when the center of the circular part 18d is misaligned with the center of the blank part 48b as shown in FIG. 8(a), the center of the circular part 18d is aligned with the center of the blank part 48b as shown in FIG. 8(b). Specifically, the position of the blank part 48b relative to the circular part 18d is adjusted so that the area of ​​the blank part 48b around the circular part 18d is maximized. Similarly, the positions of the four blanks 48b in the two reinforcing terminals 48 on the printed circuit board 20 side of the FFC 40 are aligned with the four circular parts 18d in the two connected terminals 18 on the printed circuit board 20, respectively. The process of aligning the center of the circular portion 18d with the center of the blank portion 48b may be performed automatically based on image recognition by a camera of the device, or may be performed manually by an operator using a magnifying glass, etc. In addition, at that time, the FFC 40 may be moved, the printed circuit boards 10, 20 (fixing portions 91, 92) may be moved, or both the FFC 40 and the printed circuit boards 10, 20 (fixing portions 91, 92) may be moved.

[0050] Next, the FFC 40 is sucked onto the printed circuit board 20 by the negative pressure from the suction holes 26. Specifically, the vacuum pump is driven to supply negative pressure to the suction holes 26 via the suction pipe.

[0051] As shown in FIG. 9, the heater tool H2 of the heater is formed to be longer than the length of the FFC 40 in the longitudinal direction. Next, the heater tool H2 presses the end of the FFC 40 on the printed circuit board 10 side downward (toward the printed circuit board 10) over the entire length. Specifically, the heater tool H2 presses and heats all the connection parts 43a (solder 45) of the FFC 40 and the reinforcing terminals 48 at both ends together, and thermocompresses them to the wiring 13 of the printed circuit board 10 and the solder 15 of the connected terminals 18 (see FIG. 10). As a result, the solder 45 of the connection parts 43a and the reinforcing terminals 48, and the solder 15 of the wiring 13 and the connected terminals 18 melt and are connected to each other. That is, the heater tool H2 connects the wiring 13 of the printed circuit board 10 to the connection side of the connection parts 43a of the FFC 40, and simultaneously connects the connected terminals 18 of the printed circuit board 10 to the reinforcing terminals 48 of the FFC 40. At this time, the heat of the heater tool H2 is transmitted by the wiring 43 in the short direction of the insulating part 41, but is difficult to be transmitted to the through holes 46 and 47 formed in the part not overlapping with the wiring 43.

[0052] Next, the heater tool H2 of the heater is raised (moved away from the FFC 40) and moved to the end of the FFC 40 on the printed circuit board 20 side. Then, in a similar manner, the end of the FFC 40 on the printed circuit board 20 side is pressed downward (toward the printed circuit board 20) over the entire length. Specifically, the heater tool H2 presses and heats all of the connection portions 43a (solder 45) of the FFC 40 and the reinforcing terminals 48 on both ends together, thermocompressing them to the wiring 13 of the printed circuit board 20 and the solder 15 of the connected terminals 18. As a result, the solder 45 of the connection portions 43a and the reinforcing terminals 48, and the solder 15 of the wiring 13 and the connected terminals 18, melt and are connected to each other.

[0053] 11, the printed circuit board 10, the FFC 40, and the printed circuit board 20 are mounted on the PLC with the FFC 40 bent. In this case, the predetermined direction is also the direction along the short side of the FFC 40 as shown by the arrow, that is, the direction in which the wiring 43 of the FFC 40 extends.

[0054] The present embodiment described above in detail has the following advantages.

[0055] Through holes 46, 47 spaced apart from each other are formed in the insulating portion 41 of the FFC 40 in a portion that does not overlap with the multiple wirings 43 (wiring portion). Therefore, in a state in which the two printed circuit boards 10, 20 are fixed to a positioning jig 90 having positioning pins 96, 97, the FFC 40 can be aligned with respect to both printed circuit boards 10, 20 by inserting the positioning pins 96, 97 into the through holes 46, 47 of the insulating portion 41 of the FFC 40, respectively. Furthermore, by inserting the positioning pins 96, 97 into the two through holes 46, 47 that are spaced apart from each other, respectively, the rotation of the FFC 40 with respect to both printed circuit boards 10, 20 can be restricted. Therefore, the connection portions 43a near both ends of the multiple wirings 43 can be accurately aligned with the wirings 13 of both printed circuit boards 10, 20, respectively.

[0056] The FFC 40 is warped so that the connection side (the side where the solder 45 is provided) of the connection parts 43a is on the inside, and the connection parts 43a near both ends in the short side direction approach each other. In contrast, the inventors of the present application have focused on the fact that the strength of the parts of the insulating part 41 where the through holes 46, 47 are formed is lower than that of other parts, and therefore the FFC 40 is likely to warp from the through holes 46, 47 as starting points. That is, by adjusting the positions where the through holes 46, 47 are formed in the insulating part 41, the warping of the FFC 40 can be controlled with high reproducibility. The two through holes 46, 47 spaced apart from each other pass through the center of the insulating part 41 in the short side direction (predetermined direction). This allows the FFC 40 to be warped so that the range including the center of the short side direction of the FFC 40 becomes the apex. For this reason, when a force is applied pressing the FFC 40 and the positioning pins 96, 97 with some misalignment between the positioning pins 96, 97 and the through holes 46, 47 of the insulating part 41, the FFC 40 is automatically guided by the warp so that the positioning pins 96, 97 approach the center in the short side direction. Therefore, even when the printed circuit boards 10, 20 and the FFC 40 are automatically aligned by a device, the FFC 40 can be accurately aligned with both of the printed circuit boards 10, 20.

[0057] Because the warping of FFC40 is utilized, it is possible to assume that the FFC40 is warped. This makes it possible to use inexpensive FFC40 that has a strong warp, which was previously difficult to use, and also makes it possible to accommodate larger FFC40.

[0058] The through holes 46, 47 are formed at both ends in the longitudinal direction (the direction perpendicular to the predetermined direction) of the insulating part 41. With this configuration, the starting points for warping of the FFC 40 can be formed at both ends in the longitudinal direction of the insulating part 41. This makes it easier to warp the entire FFC 40 so that the apex is in the range including the center in the short side direction.

[0059] The through holes 46, 47 are formed in a circular shape, and the centers 46a, 47a of the through holes 46, 47 are located at the center (on the center line C1) in the short-side direction of the insulating part 41. With this configuration, it becomes easier to warp the entire FFC 40 so that the center in the short-side direction becomes the apex.

[0060] The reinforcing terminals 48 are formed from a conductive material with a width wider than the width of the wiring 43, and are disposed at both longitudinal ends and both lateral ends of the FFC 40. Therefore, by forming the connected terminals 18 on the printed circuit boards 10, 20 at positions corresponding to the reinforcing terminals 48 of the FFC 40 and connecting the connected terminals 18 of the printed circuit boards 10, 20 to the reinforcing terminals 48 of the FFC 40, the connection strength between the printed circuit boards 10, 20 and the FFC 40 can be improved.

[0061] The through holes 46, 47 are formed at both longitudinal ends of the insulating part 41 and between the two reinforcing terminals 48. Therefore, the through holes 46, 47 can be formed by utilizing the portions of the insulating part 41 at both longitudinal ends that do not overlap with the reinforcing terminals 48. Therefore, in the FFC 40 in which the reinforcing terminals 48 and the through holes 46, 47 are formed, it is possible to prevent the length of the FFC 40 in the longitudinal direction from becoming long.

[0062] The through holes 46, 47 formed at both longitudinal ends of the insulating part 41 are different in size. With this configuration, it is possible to prevent the FFC 40 from being oriented in the wrong direction or the wrong front and back when connecting the FFC 40 to the two printed circuit boards 10, 20.

[0063] The positioning jig 90 includes a first fixing portion 91 for fixing the printed circuit board 10 and a second fixing portion 92 for fixing the printed circuit board 20, and the positioning pins 96, 97 are disposed between the first fixing portion 91 and the second fixing portion 92. The method for connecting the printed circuit boards 10, 20 and the FFC 40 includes a process for fixing the printed circuit board 10 to the first fixing portion 91 and fixing the printed circuit board 20 to the second fixing portion 92. According to this process, the FFC 40 can be easily aligned with the printed circuit board 10 fixed to the first fixing portion 91 and the printed circuit board 20 fixed to the second fixing portion 92.

[0064] The center of the space 48b and the center of the circle 18d are aligned with each other when the positioning pins 96, 97 are inserted into the through holes 46, 47. Therefore, after the FFC 40 is aligned with respect to both printed circuit boards 10, 20 by the positioning pins 96, 97, the position of the FFC 40 with respect to the printed circuit boards 10, 20 can be fine-tuned using the space 48b and the circle 18d.

[0065] Since the blank portion 48b is included in the reinforcing terminal 48 of the FFC 40, the blank portion 48b can be formed at the same time as the reinforcing terminal 48 is formed on the FFC 40. Furthermore, since the circular portion 18d is included in each of the connected terminals 18 of the printed circuit boards 10, 20, the circular portion 18d can be formed at the same time as the connected terminals 18 are formed on the printed circuit boards 10, 20. Moreover, by connecting the connected terminals 18 of the printed circuit boards 10, 20 and the reinforcing terminals 48 of the FFC 40, the connection strength between the printed circuit boards 10, 20 and the FFC 40 can be improved.

[0066] By pressing and heating the connection portion 43a and the reinforcing terminal 48 of the FFC 40 together with the heater tool H2, the wiring 13 of the printed circuit boards 10 and 20 and the connection side of the connection portion 43a of the FFC 40 are connected, and at the same time, the connected terminal 18 of the printed circuit boards 10 and 20 and the reinforcing terminal 48 of the FFC 40 are connected. This allows efficient connection between the printed circuit boards 10 and 20 and the FFC 40. Furthermore, since the through holes 46 and 47 are formed in a portion of the insulating portion 41 that does not overlap with the multiple wirings 43, even if the heat of the heater tool H2 is transmitted along the multiple wirings 43, it is possible to suppress deformation of the through holes 46 and 47 due to heat. This allows suppression of misalignment of the FFC 40 with respect to the printed circuit board 20 on the opposite side to the heater tool H2 when the wiring 13 of the printed circuit board 10 and the connection side of the connection portion 43a of the FFC 40 are connected with the heater tool H2.

[0067] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0068] The blank portion 48b (first positioning mark) and the circular portion 18d (second positioning mark) may be omitted.

[0069] The heater tool H2 may be separated into a heater tool that presses all the connection portions 43a (solder 45) of the FFC 40 and a heater tool that presses each of the reinforcing terminals 48. Furthermore, the timing for pressing all the connection portions 43a (solder 45) and the timing for pressing each of the reinforcing terminals 48 may be different.

[0070] The reinforcing terminal 48 and the connected terminal 18 may be omitted.

[0071] Instead of the solders 15 and 45, an anisotropic conductive film (ACF) may be used to connect the printed circuit boards 10 and 20 and the FFC 40.

[0072] The through holes 46 and 47 may be the same size. Furthermore, the through holes 46, 47 are not limited to being circular, and may be elliptical, square, rectangular, triangular, or other polygonal. Even in these cases, the cross-sectional shape of the positioning pins 96, 97 may be matched to the shape of the through holes 46, 47.

[0073] As shown in FIG. 12, the through hole 47 may be formed in a portion of the insulating portion 41 other than the end portion in the longitudinal direction. The center 47a of the through hole 47 is located on the center line C1 (the center in the short-side direction). Even in this case, the FFC 40 is likely to warp from the through holes 46 and 47 as starting points, and the rotation of the FFC 40 can be restricted by inserting the positioning pins 96 and 97 into the through holes 46 and 47, respectively. Note that the through hole 47 may also be formed in the end portion in the longitudinal direction of the insulating portion 41, and the through hole 46 and the two through holes 47 may be formed in the insulating portion 41. That is, it is sufficient that at least two through holes passing through the center in the short-side direction (predetermined direction) and spaced apart from each other are formed in the portion of the insulating portion 41 that does not overlap with the wiring 43 (wiring portion).

[0074] As shown in FIG. 13, the centers 46a, 47a of the through holes 46, 47 do not have to be located on the center line C1 (the center in the short-side direction). Even in this case, if the through holes 46, 47 pass through the center (center line C1) in the short-side direction (predetermined direction), when the FFC 40 is guided by the warp, the end of the through holes 46, 47 reaches the tip of the positioning pin 96, 97, and the position of the FFC 40 can be aligned with the positioning pin 96, 97, and further with respect to the printed circuit boards 10, 20. Even in the case of the configuration shown in FIG. 13, the relative positions of the printed circuit boards 10, 20 and the positioning pin 96, 97 may be adjusted according to the positions of the through holes 46, 47 in the insulating part 41. Therefore, it is sufficient that at least two through holes are formed in the insulating part 41 that pass through the center in the short-side direction and are spaced apart from each other.

[0075] ·As the film circuit, an FPC (Flexible Printed Circuit) can be used instead of an FFC. In that case, it is sufficient that the electric circuit (wiring part) is formed of a conductive material such as copper foil on a thin and soft insulating base film made of polyimide or the like. Even in such a configuration, warping of the FPC (film circuit) may occur due to the asymmetry of the configuration in the thickness direction of the FPC. The base film (insulating part) may cover both sides of the electric circuit so as to expose the connection part of the electric circuit, or may cover only one side of the electric circuit so as to expose the connection part of the electric circuit.

[0076] The printed circuit boards 10 and 20 and the film-like circuits (FFC 40, FPC, etc.) may be mounted on devices other than PLCs. In short, the film-like circuits (FFC 40, FPC, etc.) of the above-described embodiment and its modified examples are applicable to film-like circuits that connect the wiring of two printed circuit boards, regardless of the device in which they are mounted.

[0077] The above-described embodiments and their modifications can be combined to the extent possible. [Explanation of symbols]

[0078] 10...printed circuit board, 13...wiring, 20...printed circuit board, 40...FFC (film-like circuit), 41...insulating portion, 43...wiring (wiring portion), 43a...connecting portion, 46...through hole, 47...through hole.

Claims

1. A film-like circuit that connects wiring of two printed circuit boards, a wiring portion formed of a conductive material and having connection portions near both ends in a predetermined direction; an insulating portion formed in a film shape from an insulating material and covering the wiring portion so as to expose a connection side of each of the connection portions; the film-shaped circuit is warped so that the connection sides of the connection parts are inward and the connection parts near both ends in the predetermined direction approach each other, The film circuit has at least two through holes that pass through the center in the predetermined direction and are spaced apart from each other in a portion of the insulating portion that does not overlap with the wiring portion.

2. The film circuit according to claim 1 , wherein the through holes are formed at both ends of the insulating portion in a direction perpendicular to the predetermined direction.

3. The through hole is formed in a circular shape, The film circuit according to claim 2 , wherein the center of the through hole is located at the center of the insulating portion in the predetermined direction.

4. a reinforcing terminal formed of a conductive material with a width greater than that of the wiring portion, the reinforcing terminal being disposed at both ends of the film-shaped circuit in a direction perpendicular to the predetermined direction and at both ends of the film-shaped circuit in the predetermined direction; The film-shaped circuit according to claim 2 or 3, wherein the through holes are formed at both ends of the insulating portion in a direction perpendicular to the predetermined direction and between the reinforcing terminals.

5. 4. The film circuit according to claim 2, wherein the through holes formed at both ends of the insulating portion in a direction perpendicular to the predetermined direction have sizes different from each other.

6. A method for connecting the film circuit according to any one of claims 1 to 3 and the two printed circuit boards, comprising: Fixing the two printed circuit boards to a positioning jig having at least two positioning pins; a step of bringing the film-like circuit and the positioning pin closer to each other so that the positioning pin is inserted into the through hole from the connection side surface of the connection portion in the film-like circuit; and guiding the film circuit by warping so that the positioning pin approaches the center in the predetermined direction.

7. the positioning jig includes a first fixing portion that fixes one of the two printed circuit boards and a second fixing portion that fixes the other of the two printed circuit boards; The positioning pin is disposed between the first fixed portion and the second fixed portion, 7. The method for connecting a printed circuit board and a film-like circuit according to claim 6, further comprising the step of fixing one of the two printed circuit boards to the first fixing portion and fixing the other of the two printed circuit boards to the second fixing portion.

8. the film-shaped circuit is made of a conductive material and has a width greater than a width of the wiring portion, and includes reinforcing terminals disposed at both ends of the film-shaped circuit in a direction perpendicular to the predetermined direction and at both ends of the predetermined direction, The reinforcing terminal includes a first positioning mark, a connection terminal is formed of a conductive material at a position on each of the two printed circuit boards corresponding to the reinforcing terminal of the film circuit, the connection terminal includes a second positioning mark corresponding to the first positioning mark, 7. The method for connecting a printed circuit board and a film-like circuit according to claim 6, further comprising the step of aligning the first positioning mark with the second positioning mark in a state in which the positioning pin is inserted into the through hole.

9. In the two printed circuit boards, wiring is formed of a conductive material at a position corresponding to the connection portion of the film circuit, 9. The method for connecting a printed circuit board and a film-like circuit as described in claim 8, comprising a step of connecting the wiring of the printed circuit board and the connection side of the connection portion of the film-like circuit by using a heater tool that presses and heats the connection portion and the reinforcing terminal of the film-like circuit, while at the same time connecting the connected terminal of the printed circuit board and the reinforcing terminal of the film-like circuit.

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