JP2009049686A - Electroacoustic transducer and fixing method of conducting wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise quality of an electroacoustic transducer by resolving poor connection between lead wire extended from a voice coil in the electroacoustic transducer and a substrate connecting the lead wire. <P>SOLUTION: In the substrate having at least two lands for each of positive and negative poles, when the lead wire extended from the voice coil is connected, temporary fixation on a first land is performed first. Next, a lead is cut off so that a cutoff end is located on a second land adjacent to the first land. Then, on the second land, main solder bonding is performed so that the cutoff end of the lead wire is covered with solder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electroacoustic transducer and a method for fixing a lead wire connected to a coil of a magnetic circuit of the electroacoustic transducer.

  For example, Patent Document 1 below describes an earphone as an example of an electroacoustic transducer.

JP 2003-219498 A

  FIG. 1 shows a configuration of an earphone described in Patent Document 1. The earphone 1 includes a magnetic circuit 5, and the voice coil 3 fixed to the lower surface of the diaphragm 4 whose outer peripheral edge is supported is positioned in the magnetic gap 6 of the magnetic circuit 5. In the earphone 1, the voice coil 3 is supplied with an electric signal, so that the voice coil 3 moves in the magnetic flux in the magnetic gap 6 together with the diaphragm 4 to vibrate the diaphragm 4. Thereby, the electric signal supplied to the voice coil 3 is converted into sound.

  The outer peripheral edge of the diaphragm 4 is supported by the frame 2, and the magnetic circuit 5 includes a magnet 5a and a yoke 5b. Further, from the voice coil 3, lead wires 3a and 3b are led out from both ends of the voice coil wire constituting the voice coil 3, and the lead wires 3a and 3b are provided on the outside of the bottom surface portion of the frame 2 for relaying. Soldered to the wiring board 10.

  As the lead wires 3a and 3b (voice coil wires), a fusible polyurethane copper-coated aluminum wire (CCAW; Copper-Clad Aluminum Wire) as shown in FIG. 2 is used. The fusible polyurethane copper-coated aluminum wire is formed by coating an aluminum (Al) wire 15a with a copper (Cu) coating 15b, then coating with an insulating coating 15c1 made of fusible polyurethane, and further coating with a fusion coating 15c2. It has a four-layer structure.

  By making the core material aluminum (Al), the mass of the entire voice coil wire is reduced, and the response characteristic (frequency characteristic) of the voice coil 3 by the magnetic circuit drive is improved. The copper (Cu) coating 15b covers the surface with copper (Cu) because aluminum is difficult to solder.

  The fusion coating 15c2 has a lower melting point than the insulating coating 15c1, and is used to apply heat when wound as a coil to melt only the outermost fusion coating 15c2 and bond the wires together. In the following description, when the insulating coating 15c1 and the fusion coating 15c2 are not particularly distinguished, they are referred to as an insulation / fusion coating 15c.

  As shown in FIG. 3, the wiring substrate 10 is formed by symmetrically forming conductor patterns 12 and conductor patterns 13 having the same shape on a substantially circular substrate. Each conductor pattern has at least two lands. That is, the conductor pattern 12 includes three lands, that is, a land 12a, a land 12b, and a land 12c, and a belt-like pattern is connected to each land. Similarly, in the conductive pattern 13, the land 13a, the land 13b, and the land 13c are connected by a strip pattern.

  The ends of the lead wires 3a (for example, the positive electrode side) led out from the voice coil 3 are soldered to the lands 12a formed on the wiring board 10. The end of the lead wire 3b (for example, the negative electrode side) is soldered to the land 13a. One end of a pair of signal lines 8a and 8b for supplying a drive signal to the voice coil is soldered to the land 12b adjacent to the land 12a and the land 13b adjacent to the land 13a. The signal lines 8 a and 8 b are covered with a covering material 9. Plugs (not shown) are provided at the other ends of the signal lines 8a and 8b, and can be connected to connectors of electronic devices.

  The frame 2 has notches 2e1 and 2e2 at the outer peripheral edge of the frame member 2b. The notches 2e1 and 2e2 are provided at positions opposed to each other in the radial direction, and the lead wires 3a and 3b led out from the voice coil 3 pass through one of the notches 2e1 and 2e2, for example, the notch 2e1. 10 is connected. In this case, the lead wires 3a and 3b are formed so as to follow the shape of the frame 2 and are fixed by an adhesive (not shown). Thereby, cutting and damage of the lead wires 3a and 3b can be prevented.

  A connection process for connecting the lead wire 3a to the land 12a will be described with reference to FIG. The connection process for connecting the lead wire 3b to the land 13a is the same, and only one lead wire 3a will be described. First, in step S1, the lead wire 3a led out from the voice coil 3 is temporarily fixed to the jig with an adhesive member such as a double-sided tape.

  Next, as in step S2, the insulating / fusion coating 15c at the position connected to the land 12a is partially removed. The preliminary removal of the insulation / fusion coating 15c is performed, for example, by bringing a soldering iron at 400 ° C. into contact with the insulation / fusion coating 15c for about 2 to 3 seconds.

  In step S3, the land 12a and the lead wire 3a are soldered. The temperature of the soldering iron is 400 ° C. and is applied for about 1.5 seconds.

  Then, after the land 12a and the lead wire 3a are joined, in step S4, unnecessary end portions of the lead wire 3a exposed outside the solder joint portion are cut.

  FIG. 5 shows a cross-section of a solder joint for explaining the above-described conventional lead wire fixing process in more detail. FIG. 5 shows an example in which the preliminary removal of the insulating / fusion coating 15c is not performed.

  As shown in FIG. 5A, heat energy is applied to the solder 16 using a soldering iron in order to perform solder bonding between the lead wire 3a and the land 12a. Then, as shown in FIG. 5B, the heat / energy applied to the solder 16 melts the insulating / fusion coating 15c, exposing the copper (Cu) coating 15b.

  As shown in FIG. 5C, an intermetallic compound is formed in the exposed portion of the copper (Cu) coating 15b by copper (Cu) and tin (Sn) in the solder, and soldering is performed. A part of the aluminum (Al) wire 15a is exposed. In addition, melting of the insulating / fusion coating 15c proceeds.

  Finally, as shown in FIG. 5D, unnecessary portions of the lead wire 3a jumping out of the solder 16 are cut. In this way, the lead wire 3a is connected to the wiring board 10.

  However, in the conventional lead wire soldering as described above, the temperature of the soldering iron is increased in order to shorten the working time. Moreover, when using lead (Pb) free solder, since melting | fusing point is high compared with eutectic solder, the operation | work at higher temperature is needed. In the high temperature soldering operation, there arises a problem that the optimum width of the soldering operation time (heating time) for performing good soldering is shortened.

  If the soldering operation time is too short, the insulating / fusion coating 15c is not sufficiently melted, so that soldering failure occurs, and conduction is unstable or cannot be conducted. If the soldering operation time is too long, as shown in FIG. 6, the intermetallic compounding of the copper (Cu) film 15b and the tin (Sn) in the solder 16 proceeds excessively, and the solder 16 and aluminum ( Al) The line 15c comes into contact. Since the bondability between the solder 16 and the aluminum (Al) wire 15a is poor, there is a possibility that conduction may become unstable.

  Conventionally, the soldering operation time (step S3 in FIG. 4) is, for example, 1.5 seconds ± 0.2 seconds, and the allowable time range is extremely short. Therefore, it was necessary for skilled workers to work.

  Further, when the aluminum (Al) wire 15a protrudes from the solder 16, the mechanical strength of the exposed portion is lowered because there is no insulating / fusion coating 15c. Furthermore, since the lead wires 3a and 3b protrude from the solder 16, there is a possibility that moisture and gas may enter from the gap between the solder and the lead wires 3a and 3b, thereby reducing the bonding stability.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, an electroacoustic transducer having a good connection between a lead wire and a wiring board, and a method for fixing a lead wire that can easily perform a stable connection between the lead wires Is to provide.

In order to solve the above-described problem, the present invention provides an electroacoustic transducer in which a conductive wire connected to a coil of a magnetic circuit and having a thermally meltable insulating coating layer on the outer periphery of a metal wire is connected to a wiring board
Conductive first and second lands formed adjacently on the wiring board;
A part of the first land is fixed by a fixing member, and a tip protruding from the first land has a conductive wire included in the electrical connection member of the second land;
The electroacoustic transducer is configured such that the conductive wire and the second land are electrically connected by the electrical joining member, and the conductive wire is fixed to the second land.

The present invention relates to a method of fixing a conductive wire, which is connected to a coil of a magnetic circuit and connects a conductive wire having an insulating coating layer that can be thermally melted to the outer periphery of a metal wire to a wiring board.
Conductive first and second lands are formed adjacent to each other on the wiring board,
Fixing a part of the conducting wire to the first land with the first fixing member;
Cutting the conducting wire so that the cutting end of the conducting wire is located inside the projection surface of the second land,
Fixing the cut end of the conducting wire with the second fixing member in an electrically connected state with the second land;
It is a method for fixing a conducting wire, characterized in that the cut end is included in the second fixing member.

  According to the present invention, since heat can be efficiently applied to the lead wire, the time required for removing the insulating and fusion coating can be shortened. This means that the heating temperature can be lowered when the soldering time is comparable. Lowering the heating temperature can slow down the rate at which the copper film is lost after removal of the insulation / fusion film, and thus increase the allowable range of soldering time. This has the advantage that a high level of proficiency is not required for the soldering operation. Further, since the cut end portion of the lead wire is included in the solder as the fixing material, the strength of soldering can be increased, and moisture can be prevented from entering from the gap.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a cross-sectional view showing an earphone 20 that is an example of an electroacoustic transducer according to an embodiment of the present invention in a state where the earphone 20 is disposed upward.

  As shown in FIG. 7, the earphone 20 is fixed to the magnetic circuit 5 including the magnet 5a and the yoke 5b, the diaphragm 4, and the lower surface of the diaphragm 4 in the same manner as the conventional earphone shown in FIG. 5, a voice coil 3 positioned in the magnetic gap 6, and a frame 2 that supports the outer peripheral edge of the diaphragm 4 and to which the magnetic circuit 5 is fixed. Further, a lead wire 3a and 3b led out from the voice coil 3 and a plug (not shown) for connecting the earphone 20 to an electronic device are provided on the wiring board 10 for relay provided outside the bottom surface of the frame 2. The signal lines 8a and 8b connected to each other are soldered.

  The diaphragm 4 is made of, for example, polymer resin material, pulp, metal material, fiber material such as carbon fiber or aramid fiber, or a material formed by mixing these materials.

  The frame 2 is made of a metal material or a resin material. In the frame 2, a frame member 2b extends from the open end of the bottomed cylinder 2a having a hole 2d at the bottom in the radial direction of the bottom surface of the bottomed cylinder. A support portion 2c for supporting the diaphragm 4 is extended from the end of the extended frame member 2b in a direction perpendicular to the frame member 2b.

  As shown in FIG. 8, the frame 2 is provided with notches 2e1 and 2e2 at the outer peripheral edge of the frame member 2b. The notches 2e1 and 2e2 are provided at positions opposed to each other in the radial direction, and the lead wires 3a and 3b led out from the voice coil 3 pass through one of the notches 2e1 and 2e2, for example, the notch 2e1. 10 and is soldered to the conductive pattern on the wiring board 10. In this case, the lead wires 3a and 3b are formed so as to follow the shape of the frame 2 and are fixed by an adhesive (not shown). Thereby, cutting and damage of the lead wires 3a and 3b can be prevented.

  The voice coil 3 is formed by winding a voice coil wire made of, for example, a fusible polyurethane copper-coated aluminum wire (CCAW) into a hollow cylindrical shape, and lead wires 3a and 3b at both ends of the voice coil wire. Is derived and connected to the wiring board 10.

  The magnetic circuit unit 5 is composed of a magnet 5a and a yoke 5b formed in a substantially perforated disk shape from a magnetic material. The magnet 5a and the yoke 5b are placed on the bottom surface of the bottomed cylinder 2a of the frame 2 so as to be concentric with each other in this order. The magnet 5a and the yoke 5b are fixed to the frame 2 by eyelet-shaped rivets 7. Thereby, a magnetic gap 6 is formed in a space where the inner periphery of the frame 2 and the outer periphery of the magnet 5a and the yoke 5b face each other.

  As shown in FIG. 9A, the wiring substrate 10 is formed by symmetrically forming conductor patterns 12 and conductor patterns 13 having the same shape on a substantially circular substrate. Each conductor pattern has at least first and second lands adjacent to each other. That is, the conductor pattern 12 includes three lands, a land 12a as a first land, a land 12b as a second land, and a land 12c as a third land. Yes. Similarly, in the conductive pattern 13, the first land 13a, the second land 13b, and the third land 13c are connected by a strip pattern. As these belt-like patterns, those having a large thermal resistance are preferable so that heat during soldering does not affect other lands.

  Further, notches 10 a and 10 b are provided at positions of the outer peripheral edge portion of the wiring substrate 10 facing in the radial direction. One notch is necessary, but two notches are preferably provided at opposing positions in terms of securing the symmetry of the parts. Further, the positions of the cutouts 10a and 10b of the wiring board 10 and the positions of the cutouts 2e1 and 2e2 of the frame 2 are substantially matched. This is because the lead wires 3 a and 3 b drawn from the notch 2 e 1 of the frame 2 are soldered on the wiring board via the notch 10 a of the wiring board 10.

  A part of the lead wires 3a and 3b is fixed to the first lands 12a and 13a by solders 16a and 17a, respectively. Cut ends (tips) of the lead wires 3a and 3b protruding from the solders 16a and 17a of the first lands 12a and 13a are included in the solders 16b and 17b of the second lands 12b and 13b. Lead wires 3a and 3b are electrically connected to lands 12b and 13b by solders 16b and 17b, respectively, and lead wires 3a and 3b are fixed to lands 12b and 13b, respectively.

  Furthermore, one end of a pair of signal lines 8a and 8b for supplying a drive signal to the voice coil is soldered to the land 12b and the land 13b, respectively. The signal lines 8 a and 8 b are covered with a covering material 9. Plugs (not shown) are provided at the other ends of the signal lines 8a and 8b, and can be connected to connectors of electronic devices.

  In the embodiment of the present invention, since the three lands are electrically connected to each other in each conductive pattern, one end of the signal lines 8a and 8b may be connected to the lands 12a and 13a. As shown in FIG. 9B, the lands 12c and 13c may be connected. When one end of the signal lines 8a and 8b is connected to the lands 12a and 13a, the signal lines 8a and 8b can be fixed without affecting the solder for fixing the lead wires 3a and 3b. Since each land is connected in a strip pattern, the degree of freedom of the connection method of the signal lines 8a and 8b can be increased.

  As will be described later, in one embodiment of the present invention, a part of each of the lead wires 3a and 3b is fixed to the first lands 12a and 13a by solder as a first fixing member. Next, the lead wires 3a and 3b are cut so that the cut ends of the lead wires 3a and 3b are located inside the projection surfaces of the second lands 12b and 13b. Then, the cut ends of the lead wires 3a and 3b are fixed to the second lands 12b and 13b with solder as a second fixing member in an electrically connected state, and the cut ends of the lead wires 3a and 3b are inside the solder. To be included.

  FIG. 10 schematically shows a state where the tip of the lead wire 3a is soldered to the land 12b. A part of the lead wire 3a is fixed by the solder 16a at the position of the land 12a. This fixing is a positioning operation for the next stage of soldering, and it is sufficient if the lead wire 3a can be fixed, and electrical connection between the lead wire 3a and the land 12a is not necessary. Then, the cut end portion of the lead wire 3a is cut to a length located inside the projection surface of the land 12b. Soldering is performed so that the cut end portion is included in the solder 16b of the land 12b.

  As shown in an enlarged view in FIG. 11, the cut end portion of the lead wire 3a is included in the solder 16b. During soldering, as indicated by arrows, thermal energy is applied not only from the periphery of the lead wire 3a but also from the aluminum (Al) wire 15a and the copper (Cu) coating 15b on the cut end face. More heat energy is transmitted to the lead wire 3a as compared with the conventional application of heat energy from the peripheral surface. Accordingly, it is possible to remove the insulating / fused coating 15c and solder it in a short time. This means that the heating temperature can be lowered when the working time is the same as the conventional one. Thereby, the intermetallic compound formation of the copper (Cu) coating 15b and the tin (Sn) in the solder 16 is difficult to proceed, and as a result, the allowable time width of the soldering operation time can be expanded as compared with the conventional case.

  Further, since the end surface of the lead wire 3a is included in the solder 16b, it is possible to prevent moisture from entering from the joint boundary between the lead wire 3a and the solder 16b, and aluminum which is not protected by the insulating / fusion coating 15c. A decrease in strength due to exposure of the (Al) wire 15a can be prevented. The effect related to the fixing of the lead wire 3a described above is the same effect as the fixing of the lead wire 3b.

  A connection process for connecting the lead wire 3a to the land 12a will be described with reference to FIGS. FIG. 13 shows a cross-section of a solder joint for explaining the above-described conventional lead wire fixing process in more detail. The connection process for connecting the lead wire 3b to the land 13a is the same, and only one lead wire 3a will be described. First, in step S11, the lead wire 3a led out from the voice coil 3 is temporarily fixed to the jig with an adhesive member such as a double-sided tape.

  Next, in step S12, the lead wire 3a is temporarily fixed to the land 12a. Temporary fixing is performed using solder. Since it is sufficient if the lead wire 3a can be fixed, the soldering operation at the time of temporary fixing is, for example, applying heat at 400 ° C. for about 0.6 seconds ± 0.5 seconds, for example. In addition, you may make it perform temporary fixation with the adhesive agent generally used containing an ultraviolet curable resin, a thermosetting resin, etc.

  As shown in FIG. 13A, in the temporarily fixed portion (solder 16a) on the land 12a, since the heating time is short, the degree to which the insulating / fused coating 15c is melted becomes smaller than the conventional one. Moreover, the intermetallic compound formation of the copper (Cu) film 15b and the tin (Sn) in the solder 16a hardly occurs.

  Subsequently, in step S13, the lead wire 3a is cut to such a length that the cut end portion of the lead wire 3a is located inside the projection surface of the land 12b.

  In step S14, a soldering operation is performed in the land 12b so that the cut end portion of the lead wire 3a is covered. For example, the soldering operation is performed at a soldering iron temperature of 350 ° C. and a working time of about 1.5 seconds ± 0.7 seconds.

  As shown in FIG. 13B and FIG. 13C, the cut end portion of the lead wire 3a is located in the solder 16b, the insulating and fusion coating 15c is melted, and the copper (Cu) coating 15b is exposed. In the exposed portion of the copper (Cu) coating 15b, an intermetallic compound is formed by copper (Cu) and tin (Sn) in the solder, and soldering is performed. A part of the aluminum (Al) wire 15a is exposed. In addition, melting of the insulating / fusion coating 15c proceeds.

  Thereafter, the signal line 8a connected to the plug is soldered to the land 12b. The signal line 8a is electrically connected to the lead wire 3a.

  In the embodiment of the present invention described above, the soldering time is 1.5 seconds, which is equal to the conventional soldering time. However, since the soldering temperature can be lowered, the allowable soldering operation time, which was about 0.4 seconds in the conventional method, can be significantly increased to 1.4 seconds.

  After connecting the lead wires 3a and 3b and the signal lines 8a and 8b to the wiring board 10 in this way, the earphone 20 is accommodated in a cover (not shown) formed by molding a resin material, for example. Such an earphone 20 can easily perform stable connection of the lead wires 3a and 3b led out from the voice coil 3, thereby improving the quality of the product.

  You may make it use the wiring board 30 of a shape as shown in FIG. The wiring board 30 has a horizontally long shape with one notch 30a projecting in the radial direction, and the layout of the lands is changed along the outer shape of the wiring board 30. Other configurations are the same as those of the wiring board 10 described above.

  As shown in FIG. 15, the notch 30 a provided in the portion where the wiring board 30 projects is positioned below the notch 2 e 1 of the frame 2. At this time, the left end position X of the wiring board 30 is preferably on the outer peripheral side with respect to the inner side position Y of the notch 2e1 of the frame 2.

  By using such a wiring board 30, the lead wires 3a and 3b are connected to the outer surface of the frame 2 while the distance between the notch 2e1 from which the lead wires 3a and 3b are led out and the notch 30a to be introduced is minimized. This eliminates the need for forming along the line. In addition, since the formed lead wires 3a and 3b need not be protected by the adhesive, the number of work steps can be reduced.

  Further, a wiring board 50 having a shape as shown in FIG. 16 may be used. The wiring board 50 has a horizontally long shape in which one notch 50a projects in the radial direction. Other configurations are the same as those of the wiring board 10 described above.

  As shown in FIG. 17, the notch 50 a provided in the portion where the wiring substrate 50 protrudes is located below the notch 2 e 1 of the frame 2. At this time, like the wiring board 30 of FIG. 15, the left end position X ′ of the wiring board 50 is preferably on the outer peripheral side with respect to the inner side position Y of the notch 2 e 1 of the frame 2. Compared with the wiring board 30, the wiring board 50 can suppress the occurrence of a contact accident by an operator.

  As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, The various deformation | transformation based on the technical idea of this invention is possible. For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as necessary.

  The above-described embodiment is an example in which the present invention is applied to an earphone. However, the present invention can also be used for a microphone device.

It is sectional drawing of the conventional earphone. It is sectional drawing of the lead wire used for the conventional earphone. It is a top view of the wiring board used for the conventional earphone. It is a flowchart for demonstrating the conventional lead wire fixing process. It is sectional drawing for demonstrating the conventional lead wire fixing process. It is sectional drawing for demonstrating the problem in the conventional lead wire fixing process. It is sectional drawing of the earphone which concerns on one Embodiment of this invention. 1 is a plan view of an earphone according to an embodiment of the present invention. It is a top view of the wiring board in one embodiment of this invention. It is an enlarged plan view of the joint part of the lead wire in one Embodiment of this invention. It is an expanded sectional view of the joined part of a lead wire in one embodiment of this invention. It is a flowchart for demonstrating the lead wire fixing process in one Embodiment of this invention. It is sectional drawing for demonstrating the lead wire fixing process in one Embodiment of this invention. It is a top view which shows the other example of the wiring board which can be applied to this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Earphone 2 ... Frame 2e1, 2e2 ... Notch 3 ... Voice coil 3a, 3b ... Lead wire 4 ... Diaphragm 5 ... Magnetic circuit 5a ... Magnet 5b ... Yoke 6 ... Magnetic gap 7 ... Rivets 8a, 8b ... Signal wire 9 ... Coating material 10, 30 ... Wiring substrate 10a, 10b ... Notch 12 ... Positive electrode Conductor pattern 12a. 12b, 12c ... Land 13 ... Negative electrode conductor pattern 13a. 13b, 13c ... Land 14 ... Opening 15a ... Aluminum (Al) wire 15b ... Copper (Cu) coating 15c ... Insulation / fusion coating 16 ... Solder 20, 40 ... earphone

Claims (8)

In an electroacoustic transducer in which a conductive wire connected to a coil of a magnetic circuit and having a thermally meltable insulating coating layer on the outer periphery of a metal wire is connected to a wiring board,
Conductive first and second lands formed adjacently on the wiring board;
A part of the first land is fixed by a fixing member, and a tip protruding from the first land has a conductive wire included in an electrical joining member of the second land;
The electroacoustic transducer in which the conducting wire and the second land are electrically connected by the electrical joining member, and the conducting wire is fixed to the second land. The electroacoustic transducer according to claim 1, wherein a lead wire from the outside is electrically joined to the second land. The electroacoustic transducer according to claim 1, wherein the first and second lands are electrically joined. The electroacoustic transducer according to claim 3, wherein a lead wire from outside is electrically joined to one of the first and second lands. The electroacoustic transducer according to claim 1, further comprising a third land that is electrically joined to the second land. 6. The electroacoustic transducer according to claim 5, wherein a lead wire from outside is electrically joined to one of the second and third lands. 2. The electroacoustic transducer according to claim 1, wherein at least a part of an outer peripheral portion of the wiring board extends to the vicinity of the lead-out position of the conductive wire. In a method of fixing a conductive wire, which is connected to a coil of a magnetic circuit and connects a conductive wire having an insulating coating layer that can be thermally melted on the outer periphery of a metal wire to a wiring board,
Conductive first and second lands are formed adjacent to each other on the wiring board,
Fixing a part of the conducting wire to the first land with a first fixing member;
Cutting the conducting wire so that the cutting end of the conducting wire is located inside the projection surface of the second land,
Fixing the cut end of the conducting wire with the second fixing member in electrical connection with the second land,
The lead wire fixing method, wherein the cut end is included in the second fixing member.

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