JP2007335260A - Connection structure between connection terminal of substrate, and covered conductor wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure soldering reliability regarding a connecting structure between a connection terminal of a substrate and a covered conductor wire when an especially thin covered wire is used. <P>SOLUTION: A connection wire 20 is soldered to the connection terminal 14 of the substrate 12, and a solder connection part 40 is formed. Here, the connection wire 20 has a conductor wire 24 exposed from the covering at the tip of the covered conductor wire 16, and a thin metal plate 18 for pin contact is caulked there partly including the covering 22. The length of the metal thin plate 18 for the pin contact is longer than that which is determined based on the size of the connection terminal 14. The caulked metal thin plate 18 for the pin contact becomes to have a pin-shaped metal thin plate 30. The solder connection part 40 is formed by means that the pin-shaped thin metal plate 30 including the conductor wire 24 and the connection terminal 14 are connected to each other by soldering at a wider contact area than that of the conductor wire 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a connection structure between a connection terminal of a substrate and a covered conductor wire, and more particularly to a connection structure between the connection terminal of the substrate and the covered conductor wire that connects a thin covered conductor wire to the connection terminal of the substrate by soldering.

  A liquid crystal display element is used as a display for displaying information in a small portable information device, and COG (Chip on Glass) technology or FPC (Flexible Print Circuit) is used to mount an electronic component on the display. Fine packaging technology is used. These are suitable for mounting a large number of connection points together, but if these technologies are used to connect one or two or several connection points on the board and external connection points, they are dedicated. It is necessary to prepare equipment, jigs, etc., which takes time and increases the cost. Under such circumstances, there are cases where the connection terminals of the substrate and the conductor wires such as the lead terminals are soldered using a simple soldering apparatus.

  In order to increase the reliability of soldering between the connection terminal of the board and the conductor wire, it is necessary to widen the contact area between the solder, the connection terminal and the conductor wire, and to manage the wettability of the solder. It is known. If the contact area between the solder and the object is small, it is difficult to ensure the connection strength because the bonding area is small. Further, if the solder wettability is poor, the connection strength is low and the reliability is lowered. Therefore, it is necessary to evaluate solder wettability. As an evaluation of the wettability of the solder, a fillet is observed. A fillet is a state in which solder is liquefied on the side surface of a lead terminal at a high temperature and sucked up by surface tension. When the solder wettability is good, the fillet changes smoothly. Therefore, the wettability of the solder can be determined by observing the fillet.

  For example, in Patent Document 1, as a structure for connecting to an electrode terminal for external connection formed to extend on one side edge of a glass substrate of a liquid crystal display element, as a conventional example, a method of sandwiching with a clip pin made of a thin metal plate, A method of soldering a flat pin terminal obtained by punching a thin metal plate to a flat electrode is described. The former has a small contact area, and the latter has a problem of short-circuiting adjacent electrode terminals when the pattern interval is small. Point out. And it is possible to prevent the solder from protruding while providing a sufficient contact area by providing notches with small circular holes on the flat pin terminals or notches formed with continuous depressions such as corrugations on both sides. Is disclosed.

  Further, in Patent Document 2, in order to ensure the determination of the wettability of the solder and ensure the connection strength after soldering, the terminal width of one soldering terminal is the center part from both ends to the opposite soldering terminal. As a drum shape gradually becoming narrower toward the surface, it is disclosed that the width or area of one soldering terminal is made narrower than the width or area of the other soldering terminal.

Japanese Utility Model Publication No. 63-115120 Japanese Patent Laid-Open No. 4-32166

  As described above, a small number of connection locations can be joined by soldering between the connection terminals of the substrate and the conductor wires using a simple soldering apparatus. By the way, in a small portable information device, a part that needs to be soldered with a simple soldering device without using COG technology or FPC connection is often fine soldering. For example, it is required to perform soldering on a connection terminal having a small area using a particularly thin conductor wire. In such a case, since it may be a thin conductor wire, the contact area with respect to the solder cannot be increased so much and the width of the soldering end portion cannot be increased with respect to the soldering central portion like the FPC wiring. It is difficult to ensure the strength at the soldering end. Further, since the connection terminals are on a small area, if the contact area with the solder is increased, the fillet on the conductor wire cannot be observed. As described above, it is difficult to ensure the reliability of soldering when particularly thin conductor wires are connected to the connection terminals of the substrate by soldering.

  An object of the present invention is to provide a connection structure between a connection terminal of a substrate and a coated conductor wire that can ensure soldering reliability. Another object of the present invention is to provide a connection structure between a connection terminal of a substrate and a coated conductor wire that can ensure the reliability of soldering using a thin conductor wire.

  In the connection structure between the connection terminal of the substrate and the covered conductor wire according to the present invention, the conductor wire is exposed from the coating at the connection terminal of the substrate and the tip of the covered conductor wire, and the exposed conductor wire and a part of the coating And a connection line in which the metal thin plate portion is crimped, and a connection portion in which the metal thin plate portion and the connection terminal arranged on the connection terminal are connected by solder.

  Moreover, it is preferable that the said conductor wire of the said connection wire has an outer diameter of 0.3 mm or less. Moreover, it is preferable that the said connecting wire is 0.8 mm or less by the outer diameter containing the said coating | cover.

  In the connection structure between the connection terminal of the substrate and the covered conductor wire according to the present invention, the substrate is a substrate on which a light emitting element of a backlight module for liquid crystal display is mounted, and the connection line is a backlight for liquid crystal display. A connection line connecting the module and an external circuit is preferable.

  With the above configuration, the connecting wire is exposed from the coating at the tip of the coated conductor wire, and the thin metal plate portion is crimped including the exposed conductor wire and a part of the coating. In the connection portion, the metal thin plate portion disposed on the connection terminal and the connection terminal are connected by solder. The thin metal plate portion crimped to the tip of the coated conductor wire has a significantly larger outer peripheral area and higher strength than the conductor wire exposed after the coating is removed. Therefore, if this is soldered to the connection terminal of the board, the contact area between the solder and the object can be secured widely in each stage and the connection strength can be improved as compared with the case of the exposed conductor wire. . The solder fillet can be sufficiently observed on the thin metal plate portion. Further, depending on the strength of the thin metal plate, for example, with respect to repeated bending or the like, it is much stronger than the exposed conductor wire. Therefore, the reliability of soldering can be improved.

  The conductor wire of the connecting wire has an outer diameter of 0.3 mm or less. The connecting wire is 0.8 mm or less in outer diameter including the coating. If the thickness is larger than this, sufficient reliability can be ensured even with a normal soldering structure. Therefore, with the above configuration, it is possible to ensure the reliability of soldering when using a particularly thin conductor wire.

  Further, this connection structure is to solder a connection line connected to an external circuit to a substrate on which a light emitting element of a backlight module for liquid crystal display is mounted. There are as few as two connection lines drawn out from the light emitting element mounting substrate. Therefore, a method of performing soldering with a simple soldering apparatus is more suitable than applying the COG technique or FPC connection method used for mounting small portable devices. In the case of such an application, the reliability of soldering can be improved by the above configuration.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the case of soldering a connection line connected to an external circuit to a substrate on which a light emitting element of a liquid crystal display backlight module is mounted is described as an example, and soldering is performed with a simple soldering device. If it is what performs this, the case where a connection line is soldered to other electronic device modules may be sufficient. The materials, dimensions, and the like described below are examples for explanation, and other materials, dimensions, and the like can be used depending on the application.

  FIG. 1 is a diagram showing a connection structure for electrically connecting a substrate 12 on which a light emitting element of a backlight module for liquid crystal display 10 is mounted and an external circuit (not shown). Here, the back surface side of the backlight module 10, that is, the back surface side opposite to the front surface side to which the liquid crystal display panel is attached and the light of the backlight is supplied is shown. A part of the back side cover is cut away to expose a part of the substrate 12 on which a light-emitting element (not shown) is mounted, and a connection terminal 14 connected to an external circuit is extended and arranged there. Has been.

  The connection terminal 14 is a rectangular conductor pattern that is connected to a terminal of a light emitting element (not shown). For example, solder plating or the like is performed on a copper wiring. In FIG. 1, two connection terminals 14 are shown corresponding to the plus terminal and the minus terminal of the light emitting element. A connection line 20 connected to an external circuit (not shown) is soldered to the connection terminal 14 by a simple soldering apparatus. In FIG. 1, the solder connection portion 40 is shown.

  FIG. 2 is a diagram for explaining the structure of the connection line 20 and the soldering method. FIG. 2A is a diagram showing elements for forming the connection line 20, and FIG. 2B is a diagram for explaining the structure of the connection line 20. (C) is a diagram illustrating a connection structure in which the connection line 20 is soldered to the connection terminal 14 of the substrate 12. FIG. 2 is also a diagram showing a procedure of a connection method between the connection terminal of the substrate and the covered conductor wire from another viewpoint. In the following, the structure of these elements will be described along the procedure. .

  In order to connect the connection terminal of the board and the connection line, first, a component constituting the connection line is prepared (component preparation step). FIG. 2A shows the state of each prepared component. That is, the coated conductor wire 16 is shown on the left side of FIG. 2A, and the pin contact metal thin plate 18 is shown on the right side.

  The covered conductor wire 16 is obtained by covering a conductor wire 24 in which a plurality of single conductor wires are stranded wires with a coating 22 made of an appropriate insulating coating material, and the conductor wire 24 is exposed at the tip thereof by removing the coating 22. Yes. The thickness of the coated conductor wire 16 is selected depending on the size of the connection terminal 14 of the substrate 12 to which the coated conductor wire 16 is connected. For example, in the case of the connection terminal 14 of about 3 mm square or less, the outer diameter including the coating 22 Is about 0.8 mm or less, and the conductor wire 24 has an outer diameter of about 0.3 mm or less. For example, as a de facto standard, a coated conductor wire having an outer diameter including a coating of 0.38 mm and a conductor wire outer diameter of 0.24 mm can be used.

  The pin contact metal thin plate 18 is used as a component of a small connector, and is a component for forming a male contact inserted into the female contact of the connector. Specifically, it is attached by caulking with an appropriate caulking jig so that the thin metal plate is wound around the outer periphery of the conductor wire, and the whole is formed into a pin shape. FIG. 2A shows a plan view and a side view of the pin contact metal thin plate 18 in a shape as it is before crimping. Since the pin contact metal thin plate 18 is commercially available in accordance with the size of the de facto standard coated conductor wire, it can be used as it is.

  Since the commercially available pin contact metal thin plate 18 is designed to be used for a connector as described above, the length thereof is sufficiently longer than the thickness of the coated conductor wire 16. When the coated conductor wire 16 is soldered to the connection terminal 14 of the substrate 12, the size of the connection terminal 14 is about several times longer and wider than the thickness of the coated conductor wire 16. Therefore, in a normal case, the length of the commercially available pin contact metal thin plate 18 is longer than the length determined by the size of the connection terminal 14 used for soldering.

  Of course, apart from this, a metal thin plate that can be attached by crimping to the tip of the coated conductor wire 16 according to the shape, size, etc. of the coated conductor wire 16 or the connection terminal 14 of the substrate 12 is prepared and used. It is good. As the material of the metal thin plate, for example, a metal that has been subjected to surface treatment such as appropriate metal plating can be used, and the thickness is preferably about 0.1 mm, for example.

  The relationship between the length of the pin contact metal thin plate 18 and the length of the conductor wire 24 is preferably set so that the former is sufficiently longer than the latter. When the conductor wire 24 is thick and its own strength is sufficient, the pin contact thin metal plate 18 can be attached by caulking while covering only the conductor wire 24 portion. Is thin and its strength is not so strong. Therefore, from the viewpoint of securing the soldering strength, which will be described later, it is desirable to set the dimensions so that the cover 22 can be crimped and attached. Further, since the dimension of the connection terminal 14 of the substrate 12 is not so large, the conductor wire 24 exposed from the coating 22 is taken into consideration that the tip of the connection wire 20 does not protrude so much from the connection terminal 14 during soldering described later. It is preferable that the length of the pin is within the range of the length of the pin contact metal thin plate 18 when crimped. Actually, since the length of the pin contact thin metal plate 18 is determined according to the thickness of the coated conductor wire 16, the length of the conductor wire 24 at the tip of the coated conductor wire 16 can be made shorter than that length. desirable.

  FIG. 2B is a diagram illustrating a state in which the pin contact metal thin plate 18 is caulked and attached to the tip of the coated conductor wire 16 to form the connection line 20 (caulking attachment process). Here, the pin contact thin plate is crimped and shown as a pin-shaped metal thin plate 30. A side view is also shown. As described above, the pin contact metal thin plate 18 is caulked by including a part of the coating 22, and the conductor wire 24 at the tip is accommodated in the pin-shaped metal thin plate 30 and protrudes beyond the end. Absent. The caulking attachment can be performed using an appropriate pin contact caulking jig.

  FIG. 2C is a view showing a state in which the connecting wire 20 is soldered to the connecting terminal 14 of the substrate 12 to form the solder connecting portion 40 (soldering step) using an appropriate soldering apparatus. As the solder, lead-free solder is used. In the above dimension example, the length of the pin contact metal thin plate 18 is set longer than the size of the connection terminal 14, and therefore, the tip of the pin-shaped metal thin plate 30 of the connection line 20 protrudes from the connection terminal 14. It is preferable not to do so. In FIG. 2 (c), the pin-shaped metal thin plate 30 is shown in an arrangement in which the tip of the pin-shaped metal thin plate 30 is within the range of the connection terminal 14. Even when the tip of the pin-shaped metal thin plate 30 protrudes from the range of the connection terminal 14, it is preferable to suppress the amount of protrusion in consideration of interference and contact with other adjacent elements.

  The characteristics of the solder connection portion 40 thus formed will be described in comparison with FIG. 3 showing a case where soldering is performed by a normal method. FIG. 3 is a diagram showing a state in which the coated conductor wire 16 described in relation to FIG. 2A is soldered to the connection terminal 14 of the substrate 12 as it is. The coated conductor wire 16 has the coating 22 removed at the tip, and the conductor wire 24 is exposed.

  As shown in FIG. 2 (c), the solder connection portion 40 formed by soldering between the connection terminal 14 and the connection line 20 of the substrate 12 extends the pin-shaped metal thin plate 30 over the range of the connection terminal 14. Covered. On the other hand, in FIG. 3 showing a normal method, the solder connection portion 60 is formed over the portion of the conductor wire 24 in the range of the connection terminal 14. Since the outer shape of the pin-shaped metal thin plate 30 is larger than that of the conductor wire 24, the solder connection portion 40 in FIG. 2C has a wider contact area than the solder connection portion 60 in FIG. It is joined. Thereby, compared with the usual method of soldering to the conductor wire 24, the connection strength in soldering improves.

  In addition, since the pin-shaped metal thin plate 30 is attached by crimping a part of the covering 22 of the covering conductor wire, the end portion on the covering 22 side of the solder connection portion 40 where the force is concentrated when a force is applied from the outside. Is reinforced by the pin-shaped metal thin plate 30. This further improves the strength of the connection structure between the connection terminal of the substrate and the coated conductor wire.

  Further, as shown in FIG. 2, the length of the pin-shaped metal thin plate 30 is sufficiently longer than the size of the connection terminal 14, and the root of the pin-shaped metal thin plate 30 is outside the solder connection portion 40. Therefore, the solder fillet can be sufficiently observed on the thin metal plate portion.

  The result of the strength test of the connection structure having the above configuration will be described with reference to FIGS. FIG. 4 is a diagram for explaining the state of a repeated bending test as a strength test, and FIG. 5 is a diagram showing the results. In the repeated bending test, for the liquid crystal display backlight module 10 having the connection structure having the above-described configuration, a weight 50 having a mass W is attached to the tip of the connection line 20, and a tensile load is applied to the connection line 20 by its own weight. In this state, the liquid crystal display backlight module 10 was shaken at an angle of ± 45 degrees with respect to the direction of the tensile load, thereby applying a bending load to the solder connection portion 40. The strength evaluation was performed by repeating the reciprocal bending of ± 45 degrees once, and repeating this to determine the number of repetitions at which the solder connection portion 40 was broken. As a comparative example, a similar test was performed on the connection structure by the normal soldering process shown in FIG.

  As the mass W of the weight 50 as a load, three types of 200 g, 150 g, and 100 g were used. In addition, since there are two connecting wires 20 for the plus terminal and for the minus terminal, each was tested. The number of samples in the test was 5. Judgment of destruction of a solder connection part was performed by whether the connection line 20 isolate | separated from the backlight module 10 for liquid crystal displays.

  FIG. 5 is a diagram showing the results of a repeated bending test. FIGS. 5A, 5B, and 5C show the number of repetitions at which the solder connection portion is broken when the mass of the weight 50 as a load is 200 g, 150 g, and 100 g, respectively. For each, the “pin contact method” column shows the results for the five samples of the connection structure of the above configuration, and the “normal soldering” column shows the results for the five samples of the connection structure of FIG. Indicates. “+” And “−” in the terminal column distinguish the types of the two connection lines 20.

  From the results shown in FIG. 5, it can be seen that the “pin contact method” of the above connection structure has a life of approximately 1.5 to 2 times in terms of the number of times of repeated bending leading to breakage compared to “normal soldering”. I understand. Thus, the connection structure has a remarkable connection strength as compared with a connection structure formed by a normal soldering process.

As an example to which the connection structure of the embodiment according to the present invention is applied, a connection structure for electrically connecting a substrate on which a light emitting element of a backlight module for liquid crystal display is mounted and an external circuit (not shown) is provided. FIG. In embodiment which concerns on this invention, it is a figure explaining the structure of a connection line, and the method of soldering. It is a figure explaining the connection structure soldered by a normal method. It is a figure explaining the mode of a repeated bending test as a strength test with respect to the connection structure of embodiment which concerns on this invention. It is a figure which compares the result of a repeated bending test about the connection structure of embodiment which concerns on this invention, and the connection structure by a normal method.

Explanation of symbols

  10 Backlight Module, 12 Substrate, 14 Connection Terminal, 16 Coated Conductor Wire, 18 Pin Contact Metal Thin Plate, 20 Connection Wire, 22 Cover, 24 Conductor Wire, 30 Pin Shape Metal Thin Plate, 40, 60 Solder Connection, 50 Weight .

Claims (4)

The connection terminal of the board,
A conductor wire is exposed from the sheath at the tip of the sheathed conductor wire, and the exposed conductor wire and a connecting wire in which the metal thin plate portion is crimped including a part of the sheath;
A connection part in which the metal thin plate part and the connection terminal arranged on the connection terminal are connected by solder;
A connection structure between a connection terminal of a substrate and a covered conductor wire, characterized by comprising: The connection structure according to claim 1,
The connection structure between the connection terminal of the substrate and the covered conductor wire, wherein the conductor wire of the connection wire has an outer diameter of 0.3 mm or less. The connection structure according to claim 1,
A connection structure between a connection terminal of a substrate and a coated conductor wire, wherein the connection wire has an outer diameter of 0.8 mm or less including the coating. The connection structure according to claim 1,
The substrate is a substrate on which a light emitting element of a backlight module for liquid crystal display is mounted,
The connection line is a connection line for connecting the liquid crystal display backlight module and an external circuit, and the connection structure between the connection terminal of the substrate and the covered conductor line.

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