Coil device, pulse transformer, electronic component, and method for manufacturing electronic component

Abstract

To provide a coil device, pulse transformer, electronic component, and method for manufacturing an electronic component that can further improve bonding strength and have excellent thermal shock resistance. [Solution] An electronic component having a wire and a terminal electrode to which the wire's lead is connected and which is at least partially covered with a deposited film. The surface of the deposited film on the terminal electrode to which the lead is connected has a glossy surface with fewer surface irregularities compared to a non-glossy surface that maintains the surface state when the deposited film was formed, and the glossy surface is located near the lead connected to the terminal electrode.

Description

Technical Field

[0001] The present invention relates to a coil device used, for example, as a pulse transformer, an electronic component, and a method for manufacturing an electronic component.

Background Art

[0002] As a coil device used, for example, as a pulse transformer, a coil device shown in Patent Document 1 is known. In this type of conventional coil device, a lead portion of a wire forming a coil may be wire-bonded to a terminal electrode having a mounting surface by thermocompression bonding.

[0003] However, in a conventional coil device, a part of the film covering the wire may remain on the mounting surface of the terminal electrode as film residue during thermocompression bonding. As a result, when the coil device is mounted on a substrate, voids or the like may occur in a connecting member such as solder that connects the mounting surface of the terminal electrode and the substrate, and cracks may occur from the voids, reducing the connection reliability.

[0004] In order to solve such inconveniences, as shown in Patent Document 2 below, it has been proposed to remove film residue by laser irradiation. In this conventional technique, the film residue is removed, and the bonding strength is remarkably improved and the bonding reliability is also improved as compared with the conventional structure in which soldering is performed in a state where the film residue exists.

[0005] However, in this conventional technique, the main purpose is to remove film residue, the output of the laser beam is high, and stripe-shaped laser irradiation marks may remain on a joining facilitation layer such as a Sn film formed on the surface of the terminal electrode, and the joining facilitation layer may be partially scraped off. Such a problem is the same in other electronic components having a terminal electrode to which a lead of a wire is connected, other than the coil device.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] This invention has been made in view of the above circumstances, and its purpose is to provide a coil device, a pulse transformer, an electronic component, and a method for manufacturing an electronic component that can further improve bonding strength and have excellent thermal shock resistance. [Means for solving the problem]

[0008] To achieve the above objective, an electronic component according to one aspect of the present invention is: Wire and An electronic component having terminal electrodes to which the leads of the wire are connected and which are at least partially covered with a deposited film, The surface of the deposited film on the terminal electrode to which the lead is connected has a glossy surface with fewer surface irregularities compared to the non-glossy surface that maintains the surface state when the deposited film was formed. The glossy surface is located near the lead connected to the terminal electrode.

[0009] In this electronic component, a glossy surface is formed on the surface of the deposited layer on the terminal electrode to which the wire leads are connected. The glossy surface is formed on the surface of a deposited film, such as a Sn plating film, which serves as a bonding-facilitating layer on the surface of the terminal electrode, and facilitates bonding with bonding materials such as solder.

[0010] The wire may be covered with an insulating coating. For example, when thermocompressing the lead of an insulating wire to the surface of a terminal electrode, coating residue may adhere to the surface of the terminal electrode near the lead. If the coating residue is removed by irradiating the surface of the terminal electrode near the lead with an energy beam such as a laser, a glossy surface is formed on the surface of the irradiated deposited film. It is thought that the glossy surface is obtained by increasing the size of the particles constituting the deposited film in the planar direction due to thermal energy from a relatively low-power energy beam such as a UV laser.

[0011] According to this electronic component, a glossy surface is formed on the surface of the deposited film located near the leads that are connected to the terminal electrodes by thermocompression bonding or the like. Since coating residue and other debris are removed, when the surface of the terminal electrodes to which the leads are connected (the mounting surface) is connected to the pads of the circuit board with a connecting material such as solder, voids are less likely to occur in the connecting material, crack formation is suppressed, and connection reliability is improved.

[0012] Furthermore, a glossy surface is formed on the surface of the deposited film located near the leads connected to the terminal electrodes by thermocompression bonding, and stripe-like grooves formed by high-power lasers such as carbon dioxide lasers are not formed on the deposited film. The deposited film with the glossy surface is continuous in the planar direction, further improving the bonding strength and reliability with the solder used for mounting, and improving thermal shock resistance.

[0013] Preferably, the glossy surface is formed on the surface of the terminal electrode over a predetermined distance along the longitudinal direction of the lead connected to the terminal electrode, and more preferably, it is formed over a range longer than the total length of the portion of the lead connected to the terminal electrode along the longitudinal direction. In other words, it is preferable that the glossy surface is formed in a range where foreign matter such as coating residue formed during heat compression bonding adheres, and where foreign matter can be removed.

[0014] Preferably, the glossy surface is formed on the surface of the terminal electrode with a predetermined width or more centered on the lead, and more preferably, the glossy surface is formed in a range with a predetermined width or more that allows for the removal of foreign matter such as coating residue formed during heat compression bonding to adhere to the surface.

[0015] The terminal electrode may have a connecting portion connected to the lead and an extension portion formed extending from the connecting portion. A continuous glossy surface may be formed on the connecting portion and the extension portion, or the connecting portion may have the glossy surface and the extension portion may have the non-glossy surface.

[0016] The extension portion may be bent at a predetermined angle relative to the splice portion. The splice portion may, for example, be a mounting surface facing the land portion of the substrate, and the extension portion bent at a predetermined angle relative to the splice portion may be the portion where a fillet of a connecting member such as solder is formed. By forming a non-glossy surface of the deposited film on the surface of the extension portion where the fillet is formed, minute irregularities are formed on the surface, making it easier for a fillet of the connecting member such as solder to be formed over a relatively large area. It is thought that molten solder can easily spread due to capillary action in the gaps of the minute irregularities.

[0017] Electronic components according to other embodiments of the present invention include: It further has a core having a winding core and a flange, The wire is wound around the aforementioned core, A portion of the extension of the terminal electrode is attached to a portion of the outer surface of the core. At least a portion of the connecting wire portion is separated from the outer surface of the core by a predetermined distance.

[0018] This electronic component is specifically a coil device, and at least a portion of the connection point of the terminal electrodes, which have a glossy surface, is separated from the outer surface of the core, thereby improving the coplanarity (flatness) of the mounting surface of the coil device. Furthermore, it improves the resistance of the substrate to distortion and vibration when the coil device is mounted on a substrate, thereby improving mounting reliability.

[0019] A coil device according to another aspect of the present invention is a coil device having a terminal electrode to which a lead of the wire is connected and which is at least partially covered with a deposited film, where the surface of the deposited film of the terminal electrode to which the lead is connected has a glossy surface with less surface irregularities compared to a matte surface that maintains the surface state when the deposited film was formed, and the glossy surface is located near the lead connected to the terminal electrode.

[0020] In this coil device, since the surface of the deposited film of the terminal electrode to which the lead is connected has a glossy surface with less surface irregularities compared to a matte surface that maintains the surface state when the deposited film was formed, it exhibits the same operational effects as the above-described electronic component.

[0021] The use of the above coil device is not particularly limited, and for example, it can be used as a pulse transformer or the like.

[0022] A method for manufacturing an electronic component according to one aspect of the present invention includes a step of thermocompression bonding a lead of a wire to the surface of a terminal electrode, and a step of irradiating an energy beam onto the surface of the terminal electrode located near the lead thermocompression bonded to the terminal electrode to smooth the surface of the deposited film formed on the surface of the terminal electrode and form a glossy surface near the lead.

[0023] In this method for manufacturing an electronic component, for example, foreign matter such as coating chips after thermocompression bonding a lead of an insulated wire to the surface of a terminal electrode can be removed by irradiating an energy beam such as a laser. At the same time, a glossy surface is formed on the surface of the deposited film irradiated with the energy beam. The glossy surface is considered to be obtained by increasing the size of the particles constituting the deposited film in the planar direction due to the thermal energy based on a relatively low-output energy beam such as a UV laser.

Brief Description of the Drawings

[0024] [Figure 1] Figure 1 is a perspective view of a coil device according to one embodiment of the present invention. [Figure 2] Figure 2 is an exploded view of the coil device shown in Figure 1. [Figure 3] Figure 3 is a magnified partial perspective view of the connection point between the terminal electrode and the lead in the coil device shown in Figure 1. [Figure 4] Figure 4 is a plan view of one of the terminal electrodes shown in Figure 3, viewed from above along the Z-axis. [Figure 4A] Figure 4A is a plan view corresponding to Figure 4, showing the state immediately after the wire leads have been thermocompressed onto the terminal electrodes. [Figure 5] Figure 5 is a cross-sectional view of the main part of the leaded terminal electrode and core, cut along the VV line in Figure 4. [Figure 6] Figure 6 is a cross-sectional view of the main part of the leaded terminal electrode and core, cut along the line VI-VI in Figure 4. [Figure 7] Figure 7 is a cross-sectional view of the main part of the coil device soldered to the circuit board. [Figure 8A] Figure 8A is a graph showing the measurement results of the deposited film surface (glossy surface) of the terminal electrode after laser irradiation. [Figure 8B] Figure 8B is a graph showing the measurement results of the surface irregularities (non-glossy surface) of the deposited film on the terminal electrode before laser irradiation. [Modes for carrying out the invention]

[0025] The embodiments will be described below.

[0026] As shown in Figure 1, the coil device 1 is a surface-mount type coil component used, for example, as a pulse transformer. The coil device 1 has a drum core 10 as a drum-shaped core member, a coil section 30, and terminal electrodes 51 to 56.

[0027] In Figure 1, the top surface of the coil device 1 in the Z-axis direction is the mounting surface when the coil device 1 is mounted on a substrate or the like. In the following description, the axis parallel to the winding axis of the coil section 30 of the coil device 1 is referred to as the X-axis, the axis parallel to the height direction of the coil device 1 is referred to as the Z-axis, and the axis approximately perpendicular to the X-axis and Z-axis is referred to as the Y-axis.

[0028] The coil device 1 is not particularly limited in its external dimensions, but for example, the X-axis length is 2.0 to 6.0 mm, the Y-axis width is 1.0 to 6.0 mm, and the Z-axis height is 1.0 to 4.0 mm.

[0029] The drum core 10 has a winding core 11 around which the coil portion 30 is wound (a rod-shaped portion located inside the coil portion 30 in Figure 1), and a pair of flange portions 12, 12 provided at both ends of the winding core 11 in the X-axis direction. In this embodiment, the cross-sectional shape of the winding core 11 is substantially quadrangular, but it may be other polygons, circles, or ellipses and is not particularly limited. As shown in Figure 1, the external shapes of the two flange portions 12, 12 are both substantially rectangular parallelepipeds of the same shape, but they may differ in shape or size from one another.

[0030] The drum core 10 is composed of a magnetic material, and includes, for example, a magnetic powder such as a magnetic material with relatively high magnetic permeability, such as Ni-Zn ferrite, Mn-Zn ferrite, or metallic magnetic material.

[0031] The two flange portions 12, 12 are arranged at a predetermined distance in the X-axis direction and are substantially parallel to each other. Both ends of the winding core portion 11 in the X-axis direction are connected to the Y-axis direction centers of the opposing inner surfaces 13, 13 of the pair of flange portions 12, 12. The groove portion 21 is optional, but its presence on the mounting surface side improves insulation between the terminal electrodes 52 (55) and 53 (56).

[0032] In each of the flange portions 12, 12, three first to third terminal electrodes 51 to 53 are formed on the mounting side 20 of one flange portion 12, and three fourth to sixth terminal electrodes 54 to 56 are arranged on the mounting side 20 of the other flange portion 12.

[0033] A coil section 30 is formed in the winding core section 11 of the drum core 10. In this embodiment, the coil section 30 is composed of four wires 31 to 34 wound around the winding core section 11, with the first wire 31 and the second wire 32 forming the primary coil as a pulse transformer, and the third wire 33 and the fourth wire 34 forming the secondary coil. The first wire 31 and the second wire 32 forming the primary coil are wound in opposite directions, and the third wire 33 and the fourth wire 34 forming the secondary coil are wound in opposite directions.

[0034] Each end (each lead) 31a-34a, 31b-34b of the four wires 31-34, which are wound in this manner, is connected to terminal electrodes 51-56 located on the flanges 12, 12 of the drum core 10 by heat crimping.

[0035] Specifically, one end 31a of the first wire 31 is connected to the first terminal electrode 51, one end 32a of the second wire 32 is connected to the second terminal electrode 52, and one end 33a and 34a of the third wire 33 and the fourth wire 34 are both connected to the third terminal electrode 53.

[0036] Furthermore, the other ends 31b and 32b of the first wire 31 and the second wire 32 are both connected to the sixth terminal electrode 56, the other end 33b of the third wire 33 is connected to the fifth terminal electrode 55, and the other end 34b of the fourth wire 34 is connected to the fourth terminal electrode 54.

[0037] By winding wires 31-34 in this configuration and connecting them to terminal electrodes 51-56, the first terminal electrode 51 and the second terminal electrode 52 become the primary coil side terminal electrodes (input side terminal electrodes), and the fourth terminal electrode 54 and the fifth terminal electrode 55 become the secondary coil side terminal electrodes (output side terminal electrodes). In addition, the third terminal electrode 53 and the sixth terminal electrode 56 become intermediate taps on the primary coil side (input side) and the secondary coil side (output side), respectively.

[0038] Each wire 31-34 is made of a coated conductor, for example, a core material made of a good conductor such as copper (Cu), covered with an insulating material such as imide-modified polyurethane, and further covered with a thin resin film such as polyester on the outermost surface. However, the materials of the core material and coating material of wires 31-34 are not limited to these.

[0039] Furthermore, the wire diameter, number of turns, winding method, and number of layers of wire wound in the coil section 30 of each wire 31 to 34 may be determined for each wire according to the required characteristics of the coil device 1. In this embodiment, the wire diameter and number of turns of each wire 31 to 34 are the same, and they are wound in pairs of wires 31 and 33 (or 32 and 34) that are wound in the same direction, and in the coil section 30, for example, four wires are wound in two layers.

[0040] Each of the terminal electrodes 51 to 56 is integrally formed by bending a metal plate-shaped terminal electrode member. The terminal electrode member is made of a metal such as copper or a copper alloy, or another conductive plate.

[0041] In this embodiment, each terminal electrode 51 to 56 has the same size and shape, and each has a connecting portion 65 and an extension portion 66. However, the connecting portions 65 of terminal electrodes 53 and 56, to which the ends of two wires are connected, may have a larger width in the Y-axis direction compared to the connecting portions 65 of the other terminal electrodes 51, 52, 54, and 55.

[0042] In this embodiment, as shown in Figure 3, for example, the extension portion 66 is formed continuously on one side of the joint portion 65 in the X-axis direction, so as to bend downward along the Z-axis from the boundary 67 with the joint portion 65. The tip portion 65a, which is at least a part of the joint portion 65, is connected to the base portion 65c or extension portion 66, which is another part of the joint portion, by a stepped portion 65b, and is separated from the mounting side surface 20, which is one of the outer surfaces of the core, by a predetermined distance. In this embodiment, the stepped portion 65b is not necessarily required to be formed; for example, without forming the stepped portion 65b, the entire joint portion 65 that is bent from the extension piece 66 fixed to the flange portion of the core may be raised at a predetermined distance from the mounting side surface 20.

[0043] In this manner, it is preferable that at least a portion of the connecting portion 65 of the terminal electrode (for example, the tip portion 65a) is not bonded to the mounting side surface 20, which is the upper surface of the flange portion 12 in the Z-axis direction, and is freely movable. By not bonding and fixing at least a portion of the connecting portion 65 (for example, the tip portion 65a) to the mounting side surfaces 20, 20 of the flange portions 12, 12, the coplanarity (flatness) of the mounting surface of the coil device 1 can be improved. In addition, the resistance to distortion and vibration of the substrate when the coil device 1 is mounted on a substrate can be improved, and mounting reliability can be improved.

[0044] In this embodiment, the splice portion 65 is positioned on the mounting surface 20, and since the ends 31a to 34a and 31b to 34b of the wires 31 to 34 are heat-pressed to the splice portion 65 in a later process, the splice portion 65 may be in close contact with the mounting surface 20, but it is more preferable to have a gap. Having a gap between the splice portion 65 and the mounting surface 20 increases the elastic deformation range of the splice portion 65, which may further improve the thermal shock resistance characteristics of the coil device 1 after mounting it to a substrate or the like. In addition, having a gap can further improve the coplanarity (flatness) of the mounting surface of the coil device 1.

[0045] As shown in Figure 3, the ends 31a and 32a of the wire (the same applies to the ends 33a-34a and 31b-34b of the other wires shown in Figure 1 / hereinafter the same) are heat-sealed to the joint section 65 for a predetermined distance from the tip 65a1 of the joint section 65 to the boundary 67 with the extension section 66, or just before that boundary. In this embodiment, the ends 31a and 32a of the wire are heat-sealed to the joint section 65 from the tip 65a1 of the joint section 65 to just before the stepped section 65b, or partway up the stepped section 65b, or beyond the stepped section 65b (just before the boundary 67).

[0046] In this embodiment, for example, as shown in Figure 6, a bonding-facilitating layer 70 is formed on at least the outer surface of the terminal electrode 51 (the same applies to 52-56 / hereinafter the same), and an intermediate layer 72 may be formed between the bonding-facilitating layer 70 and the terminal electrode 51. The bonding-facilitating layer 70 and the intermediate layer 72 are single-layer or multi-layer deposited films formed on the outer surface (possibly the inner surface) of the terminal electrode 51 by a plating method or the like. In this embodiment, the bonding-facilitating layer 70 is made of Sn or a Sn alloy, and the intermediate layer is made of Ni or a Ni alloy, Ag or an Ag alloy, Cu or a Cu alloy, etc.

[0047] In this embodiment, the conductive wire 31 (and wires 32-34 similarly / hereinafter the same) is covered with an insulating coating 31, but at the end 31a of the wire that is heat-compressed to the terminal electrode 51, the insulating coating 31 is removed during heat compression. The end 31a of the conductive wire 31, from which the insulating coating 31 has been removed by the pressure and heat during heat compression, is tightly connected from the tip 65a1 of the terminal electrode 51 to the tip 31a1 of the wire end 31a, to the surface of the bonding-facilitating layer 70 or the surface of the intermediate layer 72, which has been pushed back at least partially by the pressure and heat during heat compression. Although not shown in the figures, the end 31a of the wire 31 has a shape that has been crushed along the Z-axis by the pressure and heat during heat compression.

[0048] Furthermore, as shown in Figure 4, a glossy surface 70a is formed around the bonding-facilitating layer (hereinafter also called Sn film) 70 located around the end (hereinafter also called lead) 31a of the wire connected to the terminal electrode 51. The glossy surface 70a has fewer surface irregularities than the non-glossy surface 70b, which is the deposited surface after the Sn film 70 is formed by the plating method, and has a glossy appearance.

[0049] Compared to the surface roughness of the non-glossy surface 70b shown in Figure 8B, the glossy surface 70a, as shown in Figure 8A, has fewer irregularities and is smoother along the distance (horizontal axis) in the surface direction of the glossy surface 70a, making it appear glossy. On the other hand, the non-glossy surface 70b, as shown in Figure 8B, has many irregularities on its surface, and due to light scattering and other factors, it appears to be a dull surface.

[0050] There are no particular limitations on the method for quantitatively expressing the difference in surface state between the glossy surface 70a after laser irradiation and the untreated, non-glossy surface 70b, which is the surface after deposition before laser irradiation. For example, the following method can be considered. As shown in Figure 8A or Figure 8B, the surface state of surface 70a or 70b is measured using a device such as a laser scanning method or a laser microscope.

[0051] In this case, the difference in surface condition can also be represented by the number of minimum values ​​of recesses of a predetermined depth or greater that exist between convex portions (maximum height) above a predetermined height on a curve indicating surface roughness with respect to the length in one direction of the surface. Alternatively, the difference in surface condition can also be represented by the length of the distance from one minimum value of a recess to the next minimum value of a recess. Note that recesses and convex portions that are less than a predetermined depth (for example, less than 0.01 μm) from a pair of adjacent convex portions are not counted.

[0052] As shown in Figure 8A, on the glossy surface 70a, the number of minimums of recesses greater than a predetermined depth is represented by the number of vertical lines in the dashed-dotted line, and the number is 15 or less along a straight-line distance of 50 μm in the surface direction. In addition, the average distance L1 from one minimum of a recess to the next is 3 μm or more.

[0053] Furthermore, as shown in Figure 8B, on the non-glossy surface 70b, the number of local minimums of recesses greater than a predetermined depth is represented by the number of vertical lines in the dashed-dotted line, and the number is 30 or more along a straight-line distance of 50 μm in the surface direction. Also, the average distance L1 from one local minimum of an adjacent recess to the next local minimum of a recess is less than 3 μm.

[0054] Furthermore, observation of the cross-sections of the Sn film 70 with a glossy surface 70a and the Sn film 70 with a matte surface 70b using an electron microscope revealed that the size of the particles constituting the glossy surface 70a was compared to the size of the particles constituting the matte surface 70b. It was confirmed that the size had more than doubled in the planar direction.

[0055] In this embodiment, as shown in Figure 5, it is preferable that the exposed surface 31a2 of the lead 31a along the Z-axis is connected to and exposed flush with the glossy surface 70a of the Sn film 70. This is because the exposed surface 31a2 of the lead 31a and the glossy surface 70a become mounting surfaces that are connected to the land portion 84 of the substrate 82 by a joining member 80 such as solder, as shown in Figure 7.

[0056] The thickness of the Sn film 70 with the glossy surface 70a is about the same as or less than the thickness of the Sn film 70 with the matte surface 70b, preferably 1.0 to 2.0 μm. Although the thickness of the Sn film with the glossy surface 70a may become thinner than that of the matte surface due to thermocompression bonding, it has been confirmed that the thickness does not change before and after laser irradiation.

[0057] Next, the manufacturing method will be explained. First, terminal electrodes 51 to 56 are installed on the drum core 10 shown in Figure 2. Although Figure 2 shows the drum core 10 with wires 31 to 34 wound around it, in practice, it is preferable to install the terminal electrodes 51 to 56 on the drum core 10 before winding the wires 31 to 34 around it.

[0058] Each terminal electrode 51 to 56 is formed by placing the connecting portion 65 of the corresponding terminal electrode member on the mounting side surface 20 and bonding the extension portion 66 to the outer surfaces 14, 14 of the flange portions 12, 12 with adhesive.

[0059] Furthermore, the method for forming the terminal electrodes 51 to 56 is not limited to the method of installing the terminal electrode members, but may also be formed by baking a printed or coated conductive film, plating, or the like.

[0060] After attaching terminal electrodes 51-53 and 54-56 to each flange portion of the drum core 10, the drum core 10 is then set in a winding machine and the wires 31-34 are wound around the winding core portion 11 of the drum core 10 in a predetermined order.

[0061] During winding, the ends 31a to 34a and 31b to 34b of the wires 31 to 34 are fixed to the joint portion 65 of the terminal electrodes 51 to 56 by heat compression. For example, in the connection of the end 32a of the second wire 32 to the joint portion 65 of the second terminal electrode 52, with the middle of the wire 32, which has been pulled by a winding machine (not shown), positioned in the joint portion 65 of the second terminal electrode 52, a heater (not shown) is pressed against the wire 32 and the joint portion 65 from above to heat them.

[0062] Through heat compression, the insulating coating 35 of the wire 32 is melted or peeled off, exposing the core material of the conductor wire 32, and the wire 32 is crimped to the connecting portion 65 of the terminal electrode 52 to make an electrical connection.

[0063] In the flange portions 12, 12 where three terminal electrodes 51-53 or 54-56 are arranged, one flange portion 12 may be heat-compressed using a single wide heater, or the four wires 31-34 may be heat-compressed using a single heater, changing the position of the heat-compression.

[0064] Furthermore, a single wide heater can simultaneously heat-seal the ends of wires 32 and 34 that are wound in the same direction. Therefore, in the coil device 1, the process of heat-sealing the ends 31a to 34a and 31b to 34b of wires 31 to 34 to terminal electrodes 51 to 56 can be simplified, and the manufacturing equipment can also be simplified.

[0065] After the heat crimping of both ends 31a to 34a and 31b to 34b of wires 31 to 34 to terminal electrodes 51 to 56 is completed, the unnecessary portion of the wires beyond the joint portion of ends 31a to 34a and 31b to 34b is cut off. For example, in the case of the first wire 31 crimped to the first terminal electrode 51, the unnecessary portion of the wire 31 beyond the crimped portion (end 32a) is cut off and removed using a wire cutter (not shown) lowered from above.

[0066] After the heat-compression bonding of both ends 31a to 34a and 31b to 34b of the wires 31 to 34 to the terminal electrodes 51 to 56, and the cutting of any unnecessary portions, the terminal electrodes 51 to 56 are subjected to laser surface treatment.

[0067] For example, as shown in Figure 4A, on the surface of the terminal electrode 51 to which the end (lead) 31a of the wire 31 is connected, for example, in the case of the first terminal electrode 51 to which the first wire 31 is spliced, residue 35a of the insulating resin (such as polyurethane) that was used as the insulating coating of the wire 31 remains.

[0068] In areas where coating residue 35a remains, the surface of the bonding-facilitating layer 70 on the outermost surface of the terminal electrode 52 is not exposed. Before laser irradiation, the surface of the bonding-facilitating layer 70 is a non-glossy surface 70a, similar to the film surface immediately after deposition of the film 70. At the joint portion 65 of the first terminal electrode 51, the exposed surface 31a2, which is the conductive surface of the lead 31a of the wire 31, is exposed for thermocompression bonding. As mentioned above, the exposed surface 31a2 is the portion where the insulating coating 35 of the wire 31 has melted or peeled off, exposing the core material (Cu in this embodiment) of the conductor wire 31.

[0069] Preferably, laser light is irradiated as an energy beam over an area wider than the length X1 along the X axis and width Y1 along the Y axis of the coating residue 35a on the surface of the joint portion 65 of the terminal electrode 51 shown in Figure 4A, to remove the coating residue 35a. At that time, the irradiation conditions (for example, the type and intensity of the laser (wavelength, peak intensity, pulse width, etc.)) are not particularly limited as long as they can remove the coating residue 35a and make the surface of the bonding-facilitating layer 70, which is a deposited film on the outermost surface of the terminal electrode 52, a glossy surface.

[0070] For example, a UV laser, which is a relatively low-power energy beam, is used to irradiate the surface of the joint portion 65 of the terminal electrode 51 within a predetermined range with laser light one or more times. The laser surface treatment may also be performed by scanning the laser light along the longitudinal direction (X-axis direction) of the lead 31a of the wire 31 at a predetermined pitch.

[0071] More specifically, using laser light with a pulse frequency of 20kHz to 60kHz, and with 1 to 3 irradiations at a scanning speed of 100mm / sec to less than 2000mm / sec, it was possible to remove the coating residue 35a and form a glossy surface 70a. The glossy surface 70a is thought to be formed when the components of the Sn film 70 melt and solidify due to the heat of the laser light.

[0072] As a result of applying laser surface treatment to a predetermined area of ​​the connecting portion 65 of the terminal electrodes 51 to 56, for example, as shown in Figures 3 and 4, most of the coating residue is removed from the first terminal electrode 52 to which the first wire 31 is connected, and a glossy surface 70a is formed on the surface of the terminal electrode 52. It is preferable that the area in which this glossy surface 70a is formed is larger than the area in which the coating residue 35a shown in Figure 4A is formed.

[0073] For example, the length X2 along the X-axis of the glossy surface 70a is preferably longer than the length X1 along the X-axis of the coating residue 35a, and preferably equal to or less than the length X0 along the X-axis of the connecting wire portion 65. Also, the width along the Y-axis of the glossy surface 70a is preferably greater than the width Y1 along the Y-axis of the coating residue 35a, and preferably equal to or less than the width Y0 along the Y-axis of the connecting wire portion 65.

[0074] In the coil device 1 of this embodiment, as shown in Figures 3 and 4, a glossy surface 70a is formed on the surface of the terminal electrode 51 (52 to 56 unless otherwise specified) to which the leads 31a (32a to 34a, 31b to 34b unless otherwise specified) of the wire 31 (32 to 34 are similar unless otherwise specified) are connected. The glossy surface 70a is formed on the surface of a deposited film such as a bonding-facilitating layer 70 formed on the surface of the terminal electrode 51, and facilitates bonding with a bonding member such as solder.

[0075] As shown in Figure 6, the wire 31 is covered with an insulating coating 35. When the lead 31a of the wire 31 is thermocompressed onto the surface of the terminal electrode 51, coating residue 35a may adhere to the surface of the terminal electrode 51 near the lead 31a, as shown in Figure 4A. When the coating residue 35a is removed by irradiating the surface of the terminal electrode 51 near the lead 31a with an energy ray such as a laser, a glossy surface 70a is formed on the surface of the irradiated bonding-facilitating layer 70, as shown in Figure 4. The glossy surface 70a is thought to be obtained by increasing the size of the particles constituting the magnetization-facilitating layer 70 in the planar direction due to thermal energy based on a relatively low-power energy ray such as a UV laser.

[0076] In this coil device 1, a glossy surface 70a is formed on the surface of the bonding-facilitating layer 70 located near the lead 31a connected to the terminal electrode 51 by thermocompression bonding, and coating residue 35a and the like are removed. Therefore, when the surface (mounting surface) of the terminal electrode 51 to which the lead 31a is connected is connected to the land portion 84 of the substrate 82 with a connecting member 80 such as solder, as shown in Figure 7, voids are less likely to occur in the connecting member 80, crack occurrence is suppressed, thermal shock resistance is improved, and connection reliability is improved. For example, in this embodiment, it has been confirmed that no cracks occur even in a 1500-cycle thermal shock test (test conditions: -40 to 125°C).

[0077] Furthermore, a glossy surface is formed on the surface of the deposited film located near the lead connected to the terminal electrode 51 by thermocompression bonding or the like, and stripe-shaped grooves formed by a high-power laser such as a carbon dioxide laser are not formed on the deposited film. The bonding-facilitating layer 70, which is a deposited film with a glossy surface 70a, is continuous in the planar direction, further improving the bonding strength and bonding reliability with the connecting member 80 for mounting, and improving thermal shock resistance.

[0078] Furthermore, in this embodiment, the glossy surface 70a is formed on the surface of the terminal electrode 51 over a predetermined distance along the longitudinal direction (approximately parallel to the X-axis) of the lead 31a connected to the terminal electrode 51, and more preferably, it is formed over a range longer than the total length of the portion of the lead 31a connected to the terminal electrode 51 along the longitudinal direction. In other words, the glossy surface 70a is formed in a laser irradiation range that can remove foreign matter such as coating residue 35a formed during thermocompression bonding.

[0079] For example, as shown in Figure 7, in this embodiment, the extension portion 66 is bent at a predetermined angle relative to the connecting portion 65, so that the connecting portion 65 becomes the mounting surface facing, for example, the land portion 84 of the substrate 52, and the extension portion 66 bent at a predetermined angle relative to the connecting portion 65 becomes the portion where a fillet 80a of the connecting member 80 such as solder is formed. Since the non-glossy surface 70b of the deposited film 70 is formed on the surface of the extension portion 66 where the fillet 80a is formed, minute irregularities are formed on the surface, making it easier for the fillet 80a of the connecting member 80 such as solder to be formed over a relatively large area. It is thought that molten solder can easily spread due to capillary action in the gaps of the minute irregularities.

[0080] Furthermore, in this embodiment, at least a portion of the connecting portion 65 of the terminal electrode, which has the glossy surface 70a shown in Figure 4, is separated from the mounting side surface 20 of the flange portion 12, which is the outer surface of the core 10, as shown in Figure 7, for example, thereby improving the coplanarity (flatness) of the mounting surface of the coil device 1. In addition, the resistance of the substrate 82 to distortion and vibration when the coil device 1 is mounted on the substrate 82 is improved, thereby improving mounting reliability.

[0081] Furthermore, in the manufacturing method according to this embodiment, foreign matter such as coating residue 35a after the leads 31a to 34b of the insulated wires 31 to 34 are thermocompressed onto the surface of the terminal electrodes 51 to 56 can be removed by irradiating with an energy ray such as a laser. At the same time, a glossy surface 70a is formed on the surface of the bonding-facilitating layer 70, which is a deposited film that has been irradiated with an energy ray. It is thought that the glossy surface 70a is obtained by increasing the size of the particles constituting the deposited film in the planar direction due to thermal energy based on a relatively low-power energy ray such as a UV laser.

[0082] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the present invention.

[0083] In the embodiment described above, as shown in Figure 1, a plate-shaped core 10a is joined by means such as adhesive to the surface of the pair of flange portions 12, 12 opposite to the mounting surface 20, thereby magnetically connecting these flange portions 12, 12. However, the plate-shaped core 10a is not necessarily required.

[0084] Furthermore, in the embodiment described above, the third terminal electrode 53 and the sixth terminal electrode 56 are formed as intermediate taps on the input and output sides, respectively, but depending on the application, the intermediate taps may be omitted. In that case, the third terminal electrode 53 and the sixth terminal electrode 56 become unnecessary, and the coil device (pulse transformer) can be constructed with just two wires.

[0085] Furthermore, in the above-described embodiment, the terminal electrodes 51-56 were attached to the flange portion 12 as separate metal plate members from the drum core 10, but they may also be formed directly on the outer surface of the flange portion by methods such as baking, plating, or vapor deposition of electrode paste. It has been confirmed that a similar glossy surface 70a can be produced even with electrodes baked with electrode paste.

[0086] Furthermore, although the present invention was described in the above-described embodiment as a suitable device for use as a pulse transformer for transmitting pulse signals via LAN cables and the like, the applications of the present invention are not limited to this. The present invention can be applied to other coil devices such as common mode filters, and can also be applied to all electronic components that connect wire leads to terminal electrodes by thermocompression bonding or other methods.

[0087] Furthermore, in the embodiment described above, the extensions 66 of the terminal electrodes 51 to 56 are bent at a predetermined angle relative to the connecting wire portion 65. However, depending on the structure of the coil device or electronic components, the extensions 66 may be arranged on the same plane as the connecting wire portion 65. [Explanation of Symbols]

[0088] 1... Coil device 10…Drum core 10a... Plate-shaped core 11…Core section 12... Guard part 13…Inner surface 14...Outer surface 20…Implementation aspects 21… Groove 30... Coil section 31-34... Wire 31a~34a, 31b~34b... Ends (leads) 31a1...tip 31a2…Exposed surface 35...Insulating coating 35a...Coating residue 51~56…Terminal electrode 65...Connection section 65a...Tip section (part of the connecting wire section) 65a1...tip 65b... Step section 65c... Base end (another part of the connecting wire section) 66...Extension part 67…boundary 70…Joining facilitation layer (Sn film / precipitated film) 70a…Glossy surface 70b…Non-gloss surface 72…Middle layer (Ni layer) 80…Connecting component (solder) 80a... Fillet 82... Circuit board 84...Land Department

Claims

1. Wire and An electronic component having terminal electrodes to which the leads of the wire are connected and which are at least partially covered with a deposited film, The surface of the deposited film on the terminal electrode to which the lead is connected has a glossy surface with fewer surface irregularities compared to the non-glossy surface that maintains the surface state when the deposited film was formed. An electronic component located near the lead to which the glossy surface is connected to the terminal electrode.

2. The electronic component according to claim 1, wherein the glossy surface is formed on the surface of the terminal electrode over a predetermined distance along the longitudinal direction of the lead connected to the terminal electrode.

3. The electronic component according to claim 1, wherein the glossy surface is formed on the surface of the terminal electrode with a predetermined width or more, centered on the lead.

4. The aforementioned terminal electrodes are The lead and the connecting portion that are connected, It has an extension portion formed by extending from the aforementioned connecting portion, The electronic component according to claim 1, wherein the connecting portion has the glossy surface and the extension portion has the non-glossy surface.

5. The electronic component according to claim 4, wherein the extension portion is bent at a predetermined angle relative to the connecting portion.

6. It further has a core having a winding core and a flange, The wire is wound around the aforementioned core, A portion of the extension of the terminal electrode is attached to a portion of the outer surface of the core. The electronic component according to claim 4 or 5, wherein at least a portion of the connecting wire portion is separated from the outer surface of the core by a predetermined distance.

7. Wire and A coil device having terminal electrodes to which the leads of the wire are connected and which are at least partially covered with a deposited film, The surface of the deposited film of the terminal electrode to which the lead is connected has a glossy surface with fewer surface irregularities compared to the non-glossy surface that maintains the surface state at the time the deposited film was formed. A coil device in which the glossy surface is located near the lead connected to the terminal electrode.

8. A pulse transformer having the coil device described in claim 7.

9. The process involves heat-pressing wire leads onto the surface of the terminal electrodes, A method for manufacturing an electronic component, comprising the steps of: irradiating the surface of a terminal electrode located near the lead that is thermocompressed to the terminal electrode with an energy ray to smooth the surface of the deposited film formed on the surface of the terminal electrode and to form a glossy surface near the lead.

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