JP5298755B2 - Coil parts manufacturing method - Google Patents

Description

  The present invention relates to a coil component and a manufacturing method thereof, and more particularly, to a balun transformer using a drum core and a manufacturing method thereof.

  Usually, a transmission line connected to an antenna or the like is an unbalanced transmission line, while a transmission line connected to a high-frequency circuit such as a semiconductor IC is a balanced transmission line. For this reason, when connecting an unbalanced transmission line and a balanced transmission line, the balun transformer which mutually converts an unbalanced signal and a balanced transmission signal is inserted between them. Here, the unbalanced signal refers to a single-ended signal based on a fixed potential (for example, ground potential), and the balanced signal refers to a differential signal.

  As the balun transformer, a type using a glasses-type core as described in Patent Document 1 and a type using a toroidal core as described in Patent Document 2 are common. However, the balun transformer using the glasses-type core and the toroidal core has a problem that it is relatively large in overall size, and it is difficult to automate the winding operation and surface mount.

On the other hand, the balun transformer using the drum core described in Patent Document 3 has the advantage that it is easy to downsize, and is suitable for automation of winding work and surface mounting. Yes.
Japanese Patent Laid-Open No. 11-135330 JP-A-8-115820 JP 2005-39446 A

  In an inductance component such as a common mode filter, since the number of turns of the two windings is equal, these two windings can be wound simultaneously. On the other hand, since the number of turns of the primary winding and the number of turns of the secondary winding do not always match in the balun transformer, it is difficult to wind them simultaneously. Even if the number of turns of the primary winding and the number of turns of the secondary winding match, it is necessary to take out the center tap from the secondary winding. It is difficult to turn. For this reason, in the balun transformer, the primary winding and the secondary winding are not wound at the same time, but are wound separately to form a two-layer winding structure. Therefore, in the winding of the primary winding and the secondary winding, they must be separately divided into two turns and connected.

  However, when performing the connection in two steps, if thermocompression for connection is performed on the terminal electrode adjacent to the terminal electrode that was initially connected, the heat from the heater chip at the time of thermocompression bonding An oxide film is formed on the surface of the terminal electrode that is first connected, and the wettability of the solder is lowered, which may cause a reduction in mounting strength and poor conduction. Such a problem may occur not only in the balun transformer but also in various coil components in which the winding wound around the drum core has a two-layer structure.

  Accordingly, an object of the present invention is to provide a coil component using a drum core having a terminal electrode that can suppress the influence of thermocompression bonding during connection and has good solder wettability.

  Another object of the present invention is to provide a method of manufacturing a coil component using a drum core having a terminal electrode with good solder wettability.

  In order to solve the above-described problem, a coil component according to the present invention includes a drum core having a core portion and a pair of flange portions provided at both ends of the core portion, a plurality of terminal electrodes provided in the flange portion, A plurality of windings wound around the core part and connected at both ends to the terminal electrode, and a part of the plurality of windings is wound on the inner peripheral side of the core part, and at least other of the plurality of windings Is partly wound around the outer peripheral side of the core, and the area of the terminal electrode connected with the winding wound around the inner peripheral side is at least the terminal connected with the winding wound around the outer peripheral side It is characterized by being larger than the area of the electrode.

  According to the present invention, the area of the terminal electrode to which the winding wound on the inner peripheral side is connected is larger than the area of the terminal electrode to which the winding wound on the outer peripheral side is connected. When connecting both ends to the terminal electrode by thermocompression bonding, the thermal load applied to the terminal electrode can be reduced, preventing a significant decrease in solder wettability due to the formation of an oxide film on the surface of the terminal electrode can do. Further, by increasing the electrode area, it is possible to compensate for a decrease in solder wettability due to a thermal load, and to prevent a decrease in mounting strength and a conduction failure.

  A coil component according to the present invention is wound around a core portion and a drum core having a pair of flange portions provided at both ends of the core portion, a plurality of terminal electrodes provided at the flange portion, and the core portion. A primary winding having both ends connected to the terminal electrode, and a secondary winding wound around the core and having both ends and the center tap connected to the terminal electrode are provided. The first wire and the second wire from the other end to the center tap, the first wire and the second wire being wound around the core in a state along each other. One of the winding and the secondary winding is wound on the outer peripheral side of the core part, and the other of the primary winding and the secondary winding is wound on the inner peripheral side of the core part. The area of the terminal electrode to which the winding wound on the inner peripheral side of the core is connected is preferably larger than the area of the other terminal electrodes. .

  The coil component manufacturing method according to the present invention includes a first connecting step of connecting one of the primary winding and the secondary winding, and the other of the primary winding and the secondary winding. A first connecting step is a step of thermocompression bonding one end and the other end of the winding to a terminal electrode having a relatively large area among the plurality of terminal electrodes. The second connecting step includes a step of thermocompression bonding one end and the other end of the winding to a terminal electrode having a relatively small area among the plurality of terminal electrodes.

  According to the present invention, since the area of the terminal electrode connected at the first time is larger than the area of the terminal electrode connected at the second time, the thermal load applied to the terminal electrode connected at the first time This can reduce the influence of solder and can prevent a decrease in wettability of solder. The “primary winding” and “secondary winding” in the present invention do not define the input side and the output side. That is, for the sake of convenience, the side connected to the unbalanced transmission line is simply defined as “primary winding” and the side connected to the balanced transmission line is simply defined as “secondary winding”. It doesn't matter.

  A so-called bifilar winding is suitable as a method of winding two wires around the core in a state along which they are aligned. Bifilar winding is a winding method often employed in common mode filters and the like, but in the common mode filter, the primary winding and the secondary winding are only bifilar wound. On the other hand, in the present invention, focusing on the symmetry of the two wires constituting the secondary winding, these two wires are wound in a state along each other like a bifilar winding. Thereby, it is possible to greatly improve the symmetry between the secondary windings, which has not been noticed so far. The “state along each other” is not limited to a state where two wires are wound while being in contact with each other, but includes a state where the wire is wound while maintaining a certain space.

  In the present invention, the plurality of terminal electrodes are provided in one of the collars and arranged in this order when viewed from one direction, and the terminal electrodes provided in the other collar are viewed in one direction. Including fourth to sixth terminal electrodes arranged in order, the area of the first terminal electrode is larger than the areas of the second and third terminal electrodes, and the area of the fourth terminal electrode is The primary winding is larger than the area of the sixth terminal electrode, and the primary winding is wound on the inner peripheral side of the core, and one end of the primary winding is connected to the first terminal electrode. The other end is connected to the fourth terminal electrode, the secondary winding is wound on the outer peripheral side of the winding core, and one end of the secondary winding is connected to the third terminal electrode. The other end is connected to the sixth terminal electrode, and the portion of the center tap of the secondary winding belonging to the first wire is connected to the fifth terminal electrode, and the second wire It is preferred that the portion belongs is connected to the second terminal electrode.

  In this case, the coil component manufacturing method according to the present invention includes a step of thermocompression bonding one end of the primary winding to the first terminal electrode, a step of winding the primary winding around the core portion, and the primary Thermocompression bonding the other end of the winding to the fourth terminal electrode, thermocompression bonding one end of the first wire and one end of the second wire to the third and second terminal electrodes, respectively, Winding the first wire and the second wire on the upper layer of the primary winding wound around the core in a state along the other, the other end of the first wire and the other end of the second wire And a step of thermocompression bonding to the fifth and sixth terminal electrodes, respectively.

  According to this, a terminal electrode can be arrange | positioned asymmetrically with respect to the centerline of the drum type core in which a terminal electrode extends in the axial direction of a core part. Therefore, the orientation of the balun transformer having the mounting direction can be easily confirmed. Further, an unbalanced transmission line is connected to the first and fourth terminal electrodes located on one side around the axis of the core part, and the third and the third positions located on the other side around the axis of the core part. Since the balanced transmission line can be connected to the sixth terminal electrode, there is no need to bypass the wiring pattern constituting the transmission line, and a linear and highly symmetric transmission line can be obtained.

  Another object of the present invention is to provide a drum core having a core portion and a pair of flange portions provided at both ends of the core portion, a plurality of terminal electrodes provided on the flange portion, and winding around the core portion. A primary winding having both ends connected to the terminal electrode, and a secondary winding wound around the core and having both ends and a center tap connected to the terminal electrode. Including a first wire up to the tap and a second wire from the other end to the center tap, the first wire and the second wire being wound around the core in a state along each other, One of the primary winding and the secondary winding is wound on the outer peripheral side of the core portion, and the other of the primary winding and the secondary winding is wound on the inner peripheral side of the core portion. Of the plurality of terminal electrodes provided on either one of the pair of flanges, the first terminal electrode to which the primary winding is connected and the secondary winding The distance between the terminal electrode connected to the second terminal electrode provided adjacent to the first terminal electrode is the distance between the second terminal electrode and the terminal electrode connected to the secondary winding. Of these, the coil component is characterized by being longer than the distance between the third terminal electrode provided adjacent to the second terminal electrode.

  In this case, the plurality of terminal electrodes are provided in one of the flanges and are arranged in this order when viewed from one direction, and the other terminal electrode is provided in the other flange and viewed from one direction. The fourth to sixth terminal electrodes arranged in order are included, and the distance between the first terminal electrode and the second terminal electrode is greater than the distance between the second terminal electrode and the third terminal electrode. The distance between the fourth terminal electrode and the fifth terminal electrode is longer than the distance between the fifth terminal electrode and the sixth terminal electrode. The one end of the primary winding is connected to the first terminal electrode, the other end of the primary winding is connected to the fourth terminal electrode, and the secondary winding is the winding core. The secondary winding is connected to the third terminal electrode, the other end of the secondary winding is connected to the sixth terminal electrode, and is connected to the center tap of the secondary winding. Chi, part belonging to the first wire is connected to the fifth terminal electrode, part belonging to the second wire is preferably connected to the second terminal electrode.

  According to the present invention, between the terminal electrode to which the primary winding is connected and the second terminal electrode provided adjacent to the first terminal electrode among the terminal electrodes to which the secondary winding is connected. As the terminal electrode is enlarged, the influence of the thermal load applied to the terminal electrode connected for the first time can be reduced, and the solder wettability is prevented from being reduced. can do.

  In the present invention, the terminal electrodes are preferably arranged asymmetrically with respect to the center line of the drum core extending in the axial direction of the core portion. The terminal electrodes are preferably arranged symmetrically with respect to the center line of the drum core extending in the direction orthogonal to the axial direction of the core portion.

  As described above, according to the present invention, it is possible to reduce the influence of the already-connected terminal electrode when the winding wound around the upper layer of the two-layer winding structure is connected by thermocompression bonding. Thus, it is possible to provide a coil component having a terminal electrode with good solder wettability.

  In addition, according to the present invention, it is possible to provide a method for manufacturing a coil component using a drum core having a terminal electrode with good solder wettability.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view of a balun transformer, which is a typical example of a coil component according to the present invention, showing the appearance of the balun transformer according to the first embodiment. 2 is a schematic cross-sectional view of the balun transformer according to the present embodiment, and FIG. 3 is a schematic bottom view of the balun transformer according to the present embodiment as viewed from the mounting surface side.

  As shown in FIGS. 1 to 3, the balun transformer 100 according to the present embodiment includes a drum core 110, a plate core 120, and three wires 131 to 133. The drum-type core 110 has a core 111 and a pair of flanges 112 and 113 provided at both ends of the core 111. One collar portion 112 is provided with three terminal electrodes 141 to 143 arranged in this order as viewed from one direction (from arrow A shown in FIG. 3). The other flange 113 is provided with three terminal electrodes 144 to 146 arranged in this order when viewed from the same direction (from arrow A shown in FIG. 3).

  The plate-like core 120 is disposed so as to connect the upper portions of the flange portions 112 and 113 of the drum core 110. Although it is not essential to use the plate core 120 in the present invention, if a closed magnetic circuit is formed by using the plate core 120, high magnetic coupling can be obtained. The drum core 110 and the plate core 120 are made of a magnetic material and are not particularly limited, but it is preferable to use a NiZn-based ferrite material. This is because NiZn-based ferrite not only has a relatively high magnetic permeability, but also has a low conductivity, so that a terminal electrode can be directly formed. However, for the plate-like core 120 on which no terminal electrode is formed, an MgZn ferrite material having higher magnetic permeability can be used.

  As shown in FIG. 3, the three wires 131 to 133 are all wound around the arrow B in the clockwise direction (clockwise). FIG. 4 is a schematic diagram for explaining a connection relationship between the wires 131 to 133 and the terminal electrodes 141 to 146. As shown in FIG. 4, one end 131 a of the wire 131 is connected to the terminal electrode 141, and the other end 131 b is connected to the terminal electrode 144. In the present embodiment, the number of turns of the wire 131 is eight. One end 132 a of the wire 132 is connected to the terminal electrode 143, and the other end 132 b is connected to the terminal electrode 145. In the present embodiment, the number of turns of the wire 132 is 4 turns. Further, one end 133 a of the wire 133 is connected to the terminal electrode 142, and the other end 133 b is connected to the terminal electrode 146. In the present embodiment, the number of turns of the wire 133 is 4 turns.

  FIG. 5 is an equivalent circuit diagram of the balun transformer 100 according to the present embodiment.

  As shown in FIG. 5, the balun transformer 100 according to the present embodiment includes primary windings L11 and L12 connected between the primary side terminal P and the ground terminal GND, a secondary side positive terminal ST and a secondary side. The secondary windings L21 and L22 are connected between the side negative terminal SB. A connection point between the secondary windings L21 and L22 is used as a center tap CT.

  In the present embodiment, four turns on the one end 131a side of the wire 131 constitute the primary winding L11, and four turns on the other end 131b side constitute the primary winding L12. The wire 132 constitutes the secondary winding L21, and the wire 133 constitutes the secondary winding L22. Therefore, the terminal electrode 141 is used as the primary terminal P, the terminal electrodes 143 and 146 are used as the secondary positive terminal ST and the secondary negative terminal SB, respectively, and the terminal electrode 144 is used as the ground terminal GND. The terminal electrodes 142 and 145 are used as the center tap CT.

  As shown in FIGS. 2 and 3, in this embodiment, the wire 131 constituting the primary winding is wound on the inner peripheral side, and the wires 132 and 133 constituting the secondary winding are wound on the outer peripheral side. Has been. Here, the wires 132 and 133 constituting the secondary winding are bifilar wound around the core portion 111. In FIG. 2, the cross section is hatched with a wire 132, and the cross section is marked with an X mark. That is, the wires 132 and 133 are wound alternately from one brim part 112 toward the other brim part 113 (or in the opposite direction). For this reason, the portions of the wires 132 and 133 that become the n-th turn (n = 1 to 4) are adjacent to each other.

  With such a winding method, as shown in FIG. 6 which is a comparative example, the wires 132 are collectively wound around the area 111 a on the flange 112 side of the core 111, and the flange 113 of the core 111 is wound. It is possible to keep the symmetry of these two wires 132 and 133 very high as compared with the case where so-called sector winding is performed in which the wire 133 is wound around the area 111b. This is because, in bifilar winding, two wires are wound almost evenly, whereas in sector winding, the center tap CT is located at the center of the core 111, so the center tap CT is connected to the terminal. This is because the symmetry of the wiring portion for connecting to the electrode is disturbed.

  Although not particularly limited, the terminal electrodes 141 to 146 according to the present embodiment are obtained by performing Ni plating and Sn plating on the silver paste baking electrodes formed on the surfaces of the flange portions 112 and 113. As described above, when NiZn-based ferrite is used as the material of the drum core 110, the terminal electrode can be directly formed. On the other hand, as a material for the wires 131 to 133, it is preferable to use Cu with high conductivity and low cost. When connecting a wire to a terminal electrode, the end of the wire can be connected by thermocompression bonding to the terminal electrode.

  As shown in FIG. 3, among the terminal electrodes 141 to 143 provided on one flange 112, the area of the terminal electrode 141 to which one end of the wire 131 is connected is the other terminal electrode provided on the flange 112. It is set to be larger than the areas 142 and 143. Similarly, among the terminal electrodes 144 to 146 provided on the other flange part 113, the area of the terminal electrode 144 to which the other end of the wire 131 is connected is the other terminal electrodes 145 and 146 provided on the flange part 113. It is set larger than the area. That is, in the two-layer winding structure, the area of the terminal electrode to which both ends of the lower layer winding (primary winding) are connected is that both ends of the upper layer winding (secondary winding) and the center tap are connected. Larger than the area of the terminal electrode. Therefore, although details will be described later, it is possible to compensate for a decrease in wettability of the solder due to the thermal load applied to the pair of terminal electrodes 141 and 144 during the connection.

  In the present embodiment, the electrode area is increased by increasing the width W1 of the terminal electrodes 141 and 144 along the longitudinal direction of the flanges 112 and 113, but the terminals are orthogonal to the longitudinal direction of the flanges 112 and 113. The electrode area may be increased by increasing the width W2 of the electrodes 141 and 144, or the electrode area may be increased by increasing both the widths W1 and W2. Furthermore, the area of the entire terminal electrode may be increased by increasing the area of the terminal electrode (see FIG. 1) formed on the side surface as well as the bottom surface of the flanges 112 and 113. The area of the terminal electrodes 141 and 144 is preferably 1.1 to 2 times that of other terminal electrodes, and particularly preferably 1.4 to 2 times. If the area of the terminal electrodes 141 and 144 is too small, the effect of preventing the solder wettability from being lowered cannot be obtained. If the area is too large, the drum core 110 must be enlarged, and the demand for miniaturization can be satisfied. Because it disappears. As an example of the electrode size, the area of the terminal electrodes 141 and 144 may be 2.0 × 1.0 mm, and the area of the terminal electrodes 142, 143, 145, and 146 may be 1.2 × 1.0 mm.

  In the present embodiment, the terminal electrodes 141 and 144 have the same size, and the terminal electrodes 142, 143, 145, and 146 have the same size. Therefore, the terminal electrodes 141 to 146 have a layout that is line-symmetric with respect to the center line of the drum core 110 that extends in the direction orthogonal to the axial direction of the core 111. On the other hand, the terminal electrodes 141 to 146 have an asymmetric layout with respect to the center line of the drum core 110 extending in the axial direction of the core portion 111. Therefore, when mounting the balun transformer 100 having circuit mounting direction on the printed circuit board, the mounting direction can be easily confirmed from the layout of the terminal electrodes.

  FIG. 7 is a view showing a wiring pattern on the printed board for mounting the balun transformer 100 according to the present embodiment.

  A mounting area 150 on the printed board shown in FIG. 7 is an area for mounting the balun transformer 100, and four land patterns 151 to 154 are provided. The land pattern 151 is a pattern connected to the unbalanced transmission line PL, and is connected to the terminal electrode 141 (primary terminal P) of the balun transformer 100. The land pattern 152 is a pattern connected to the ground wiring GNDL, and is commonly connected to the terminal electrode 144 (ground terminal GND) and the terminal electrodes 142 and 145 (center tap CT) of the balun transformer 100. The land patterns 153 and 154 are patterns connected to the pair of balanced transmission lines STL and SBL, and the terminal electrode 143 (secondary positive terminal ST) and the terminal electrode 146 (secondary negative terminal SB) of the balun transformer 100, respectively. Connected to.

  With such a layout, the unbalanced transmission line PL can be formed linearly in the direction of the arrow C when viewed from the mounting region 150, and the pair of balanced transmission lines STL and SBL are viewed from the mounting region 150 as indicated by the arrow D. It can be formed parallel and linear to the direction. This eliminates the need for bypassing the wiring pattern on the printed circuit board, so that the occupied area of the wiring pattern does not increase more than necessary, and the symmetry of the wiring pattern can be ensured. As a result, it is possible to simultaneously reduce the size of the entire apparatus and improve the signal quality.

  In the present embodiment, the area of the land patterns 151 and 152 is preferably larger than the land patterns 153 and 154. In mounting the pulse transformer 100, the terminal electrodes 141 and 144 must be connected to the land patterns 151 and 152, and the terminal electrodes 143 and 146 must be connected to the land patterns 153 and 154. If the size relationships of the pattern areas match, the mounting direction of the pulse transformer 100 can be easily confirmed. Accordingly, it is possible to prevent erroneous connection such that the terminal electrodes 141 and 144 are erroneously connected to the land patterns 153 and 154 and the terminal electrodes 143 and 146 are erroneously connected to the land patterns 151 and 152.

  As described above, in the balun transformer 100 according to the present embodiment, the electrode areas of the terminal electrodes 141 and 144 to which both ends of the wire 131 constituting the primary winding wound on the inner peripheral side of the core 111 are crimped are as follows. Since it is relatively large, it is possible to reduce the thermal load applied to the terminal electrodes 141 and 144 when both ends of the wires 132 and 133 constituting the secondary winding are thermocompression bonded to the terminal electrodes. A significant decrease in solder wettability due to the formation of an oxide film on the surface of 144 can be prevented. Further, by increasing the electrode area, it is possible to compensate for a decrease in solder wettability due to a thermal load, and to prevent a decrease in mounting strength and a conduction failure. Furthermore, since the electrode areas of the terminal electrodes 141 and 144 are larger than those of the other terminal electrodes, an asymmetric electrode layout can be realized, and a structure with a clear mounting direction can be obtained.

  In addition, according to the present embodiment, since the two wires 132 and 133 constituting the secondary winding are bifilar wound, the symmetry 132 of the two wires is compared to the case where these are sector-wound. 133 can be kept very high. As a result, it is possible to obtain a good amplitude balance and phase balance particularly in the high frequency range. Moreover, since all the wires 131 to 133 are wound in the same direction, no crossing of the wires occurs in the winding core portion 111. For this reason, short-circuit defects and the like hardly occur, and the reliability of the product can be improved.

  8A to 8E are schematic views for explaining a method for manufacturing the balun transformer 100. FIG.

  In the manufacture of the balun transformer 100, first, the drum core 110 on which the terminal electrodes 141 to 146 are formed and the three wires 131 to 133 are prepared.

  Next, as shown in FIG. 8A, one end 131a of the wire 131 to be the primary winding is fixed to the terminal electrode 141 by thermocompression bonding. In thermocompression bonding, the tip of the wire is fused to the terminal electrode by pressing the heater chip 160 heated to about 400 to 800 ° C. against the terminal electrode while the tip of the wire is in contact with the terminal electrode. Thereby, the tip of the wire is in a state of being electrically and mechanically connected to the terminal electrode.

  Next, as shown in FIG. 8B, after the wire 131 is wound around the core 111 of the drum core 110 with a predetermined number of turns (for example, 8 turns), the other end 131b of the wire 131 is connected to the terminal electrode. Fix to 144 by thermocompression bonding.

  Next, as shown in FIG. 8C, one end 132a of the wire 132 and the one end 133a of the wire 133, which are the secondary winding, are fixed to the terminal electrodes 143 and 142 by thermocompression. At this time, heat from the heater chip 160 is also indirectly applied to the terminal electrode 141 adjacent to the terminal electrode 142, and the surface state of the terminal electrode 141 changes due to the thermal load. In this embodiment, the terminal electrode 141 is changed. Is set relatively large, and the influence of heat is dispersed, so that the entire surface of the terminal electrode 141 does not change greatly. Further, even if the surface of the terminal electrode is changed slightly, the required solder wettability can be ensured because the electrode area is large. Therefore, it is possible to prevent a decrease in wettability of the solder on the surface of the terminal electrode 141.

  Next, as shown in FIG. 8D, the wires 132 and 133 are wound around the core part 111 with a predetermined number of turns (for example, 4 turns). In particular, the wires 132 and 133 are wound by bifilar, and are wound on the exposed surface of the wire 131 wound around the core 111. As a result, the balun transformer 100 has a two-layer winding structure. As described above, when the two wires 132 and 133 constituting the secondary winding are bifilar wound, the symmetry of the wires 132 and 133 can be kept very high as compared with the case where these are sector wound. It becomes possible. Therefore, it is possible to obtain a favorable amplitude balance and phase balance particularly in the high frequency range.

  Next, as shown in FIG. 8E, the other ends 132a and 133a of the wires 132 and 133 are fixed to the terminal electrodes 145 and 146 by thermocompression bonding, respectively. At this time, heat from the heater chip 160 is also indirectly applied to the terminal electrode 144 adjacent to the terminal electrode 145, and the surface state of the terminal electrode 144 changes due to the thermal load. In the present embodiment, the terminal electrode 144 is changed. Is set relatively large, and the influence of heat is dispersed, so that the entire surface of the terminal electrode 144 does not change greatly. Further, even if the surface of the terminal electrode is changed slightly, the required solder wettability can be ensured because the electrode area is large. Accordingly, it is possible to prevent a significant decrease in solder wettability on the surface of the terminal electrode 144. Thus, the balun transformer 100 according to the present embodiment is completed.

  Next, a second preferred embodiment of the present invention will be described.

  FIG. 9 is a schematic sectional view of a balun transformer according to a second embodiment of the present invention, and FIG. 10 is a schematic bottom view of the balun transformer according to the present embodiment as viewed from the mounting surface side.

  As shown in FIG. 9, in the balun transformer 200 according to the present embodiment, the wires 132 and 133 constituting the secondary winding are wound on the inner peripheral side, and the wire 131 constituting the primary winding is wound on the outer peripheral side. It is characterized by being turned. Further, the wires 132 and 133 are wound around the core 111 by bifilar. Also in FIG. 9, the wire 132 is hatched in the cross section, and the wire 133 is marked in the cross section. That is, the wires 132 and 133 are wound alternately from one brim part 112 toward the other brim part 113 (or in the opposite direction). For this reason, the portions of the wires 132 and 133 that become the n-th turn (n = 1 to 4) are adjacent to each other.

  Also, as shown in FIG. 10, among the terminal electrodes 141 to 143 provided on one collar part 112, the area of the terminal electrode 142 to which one end of the wire 133 is connected is the other area provided on the collar part 112. The area is set larger than the area of the terminal electrodes 141 and 143. Similarly, among the terminal electrodes 144 to 146 provided on the other flange portion 113, the area of the terminal electrode 145 to which the other end of the wire 132 is connected is the other terminal electrodes 144 and 146 provided on the flange portion 113. It is set larger than the area. That is, the area of the terminal electrode to which both ends of the lower layer winding (secondary winding) are connected in the two-layer winding structure is that both ends of the upper layer winding (primary winding) and the center tap are connected. Larger than the area of the terminal electrode. Since other configurations are substantially the same as those of the balun transformer 100 according to the first embodiment, the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  As described above, the balun transformer 200 according to the present embodiment includes the terminal electrode 142 and the other end of the wire 132 to which one end of the wire 133 constituting the secondary winding wound around the inner peripheral side of the core 111 is crimped. Since the electrode area of the terminal electrode 145 is relatively large, the heat applied to the terminal electrodes 142 and 145 when both ends of the wire 131 constituting the primary winding are thermocompression bonded to the terminal electrodes 141 and 144. The load can be reduced, and a significant reduction in solder wettability due to the formation of an oxide film on the surfaces of the terminal electrodes 142 and 145 can be prevented. Further, by increasing the electrode area, it is possible to compensate for a decrease in solder wettability due to a thermal load, and to prevent a decrease in mounting strength and a conduction failure.

  In addition, according to the present embodiment, since the two wires 132 and 133 constituting the secondary winding are bifilar wound, the symmetry 132 of the two wires is compared to the case where these are sector-wound. 133 can be kept very high. As a result, it is possible to obtain a good amplitude balance and phase balance particularly in the high frequency range. Moreover, since all the wires 131 to 133 are wound in the same direction, no crossing of the wires occurs in the winding core portion 111. For this reason, short-circuit defects and the like hardly occur, and the reliability of the product can be improved.

  FIGS. 11A to 11E are schematic views for explaining a method of manufacturing the balun transformer 200. FIG.

  In the manufacture of the balun transformer 200, first, the drum core 110 on which the terminal electrodes 141 to 146 are formed and the three wires 131 to 133 are prepared.

  Next, as shown in FIG. 11A, the one ends 132a and 133a of the two wires 132 and 133 serving as the secondary windings are fixed to the terminal electrodes 143 and 142 by thermocompression, respectively. As described above, in thermocompression bonding, the heater tip 160 heated to about 400 to 800 ° C. is pressed against the terminal electrode while the tip of the wire is in contact with the terminal electrode, and the tip of the wire is fused to the terminal electrode. Thereby, the tip of the wire is in a state of being electrically and mechanically connected to the terminal electrode.

  Next, as shown in FIG. 11B, the wires 132 and 133 are wound around the core 111 of the drum core 110 with a predetermined number of turns (for example, 4 turns). At this time, the wires 132 and 133 are wound by the bifilar, so that the wires 132 and 133 are wound around the winding core portion 111 with a predetermined number of turns (for example, 4 turns) along each other. As described above, when the two wires 132 and 133 constituting the secondary winding are bifilar wound, the symmetry of the wires 132 and 133 can be kept very high as compared with the case where these are sector wound. It becomes possible. Therefore, it is possible to obtain a favorable amplitude balance and phase balance particularly in the high frequency range. Thereafter, the other ends 132a and 133a of the wires 132 and 133 are fixed to the terminal electrodes 145 and 146, respectively, by thermocompression bonding.

  Next, as shown in FIG. 11C, one end 131a of the wire 131 to be the primary winding is fixed to the terminal electrode 141 by thermocompression bonding. At this time, heat from the heater chip 160 is also indirectly applied to the terminal electrode 142 adjacent to the terminal electrode 141, and the surface state of the terminal electrode 142 changes due to the thermal load. In this embodiment, the terminal electrode 142 is changed. Is set relatively large, and the influence of heat is dispersed, so that the entire surface of the terminal electrode 142 does not change significantly. Further, even if the surface of the terminal electrode is changed slightly, the required solder wettability can be ensured because the electrode area is large. Accordingly, it is possible to prevent a significant decrease in solder wettability on the surface of the terminal electrode 142.

  Next, as shown in FIG. 11D, the wire 131 is wound around the core portion 111 with a predetermined number of turns (for example, 8 turns). In particular, the wire 131 is wound around the exposed surfaces of the wires 132 and 133 wound around the core 111. As a result, the balun transformer 200 has a two-layer winding structure.

  Next, as shown in FIG. 11E, the other end 131b of the wire 131 is fixed to the terminal electrode 144 by thermocompression bonding. At this time, heat from the heater chip 160 is also indirectly applied to the terminal electrode 145 adjacent to the terminal electrode 114, and the surface state of the terminal electrode 145 changes due to the thermal load. In the present embodiment, the terminal electrode 145 is changed. Is set relatively large, and the influence of heat is dispersed, so that the entire surface of the terminal electrode 144 does not change greatly. Further, even if the surface of the terminal electrode is changed slightly, the required solder wettability can be ensured because the electrode area is large. Therefore, it is possible to prevent a decrease in wettability of the solder on the surface of the terminal electrode 145. Thus, the balun transformer 200 according to the present embodiment is completed.

  Next, a preferred third embodiment of the present invention will be described.

  FIG. 12 is a schematic bottom view of the balun transformer according to the third embodiment of the present invention as viewed from the mounting surface side.

  As shown in FIG. 12, in the balun transformer 300 according to the present embodiment, the terminal electrodes 141 to 146 have the same area, but the distance D1 between the terminal electrodes 141 and 142 is greater than the distance D2 between the terminal electrodes 142 and 143. Similarly, the distance D1 between the terminal electrodes 141 and 142 is set to be longer than the distance D2 between the terminal electrodes 142 and 143. Since other configurations are substantially the same as those of the balun transformer 100 according to the first embodiment, the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  In the present embodiment, a winding structure in which the primary winding as shown in FIG. 2 is on the inner peripheral side and the secondary winding is on the outer peripheral side may be used, and the secondary winding as shown in FIG. A winding structure in which the inner peripheral side and the primary winding are the outer peripheral side may be employed. In the former case, since the terminal electrodes 141 and 144 are separated from the terminal electrodes 142 and 145, when the both ends of the wires 132 and 133 serving as the secondary winding are thermocompression bonded to the terminal electrodes, The heat load applied to 144 can be reduced. In the latter case, since the terminal electrodes 142 and 145 are separated from the terminal electrodes 141 and 144, when both ends of the wire 131 serving as the primary winding are thermocompression bonded to the terminal electrodes, the terminal electrodes 142, The heat load applied to 145 can be reduced.

  As described above, in the balun transformer 300 according to the present embodiment, the terminal electrode 141 to which the primary winding is connected and the secondary winding among the terminal electrodes 141 to 143 provided on the one flange 112 are connected. The distance D1 between the terminal electrodes 142 and 143 and the terminal electrode 142 provided adjacent to the terminal electrode 141 is the distance D2 between the terminal electrode 142 and the terminal electrode 143 provided adjacent thereto. Therefore, when both ends of the winding wound on the outer peripheral side are thermocompression bonded to the terminal electrode, the thermal load applied to the terminal electrode to which the inner peripheral winding is already connected can be reduced. Therefore, it is possible to prevent a decrease in wettability of solder in the terminal electrode. Similarly, among the terminal electrodes 144 to 146 provided on the other flange 113, the terminal electrode 144 to which the primary winding is connected and the terminal electrode 145 and 146 to which the secondary winding is connected are terminal electrodes. The distance D1 between the terminal electrode 145 provided adjacent to the terminal 144 is longer than the distance D2 between the terminal electrode 145 and the terminal electrode 146 provided adjacent to the terminal electrode 145. When both ends of the wound winding are thermocompression bonded to the terminal electrode, the thermal load applied to the terminal electrode to which the inner winding is already connected can be reduced, and an oxide film is formed on the surface of the terminal electrode. It is possible to prevent a decrease in wettability of the solder due to the formation. Furthermore, since the distance D1 between the terminal electrodes 141 and 144 and the adjacent electrode is longer than the distance D2 between the other terminal electrodes, an asymmetric electrode layout can be realized, and thereby the direction of mounting the balun transformer 100 is clear. Structure.

  In addition, according to the present embodiment, since the two wires 132 and 133 constituting the secondary winding are bifilar wound, the symmetry 132 of the two wires is compared to the case where these are sector-wound. 133 can be kept very high. As a result, it is possible to obtain a good amplitude balance and phase balance particularly in the high frequency range. Moreover, since all the wires 131 to 133 are wound in the same direction, no crossing of the wires occurs in the winding core portion 111. For this reason, short-circuit defects and the like hardly occur, and the reliability of the product can be improved.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, in each of the above embodiments, the two wires constituting the secondary winding are bifilar wound, but are not limited to bifilar winding as long as they are wound in a state along each other. Therefore, as shown in FIG. 21, a twisted wire 10 in which two wires 11 and 12 are twisted is used, and such a twisted wire 10 is wound around a winding core portion to be used as a secondary winding. It doesn't matter.

  In each of the above embodiments, the conductive paste is directly formed on the bottom surfaces of the flanges 112 and 113 of the drum core 110, and then the terminal electrodes are formed by plating. The terminal electrode can be mechanically attached by fitting a U-shaped electrode metal fitting from the side surfaces of the flange portions 112 and 113, for example.

  In the present specification, the third embodiment is described separately from the first and second embodiments, but the first embodiment and the third embodiment may be combined. It is possible to combine the second embodiment and the third embodiment. That is, each terminal electrode may be formed so that the area of the terminal electrode to which the winding wound first is connected is increased and the distance from the adjacent terminal electrode is increased. Furthermore, the number of terminal electrodes does not have to be three for each pair of flanges, and for example, four terminal electrodes can be formed for each pair of flanges.

  Further, in each of the above embodiments, a balun transformer that exhibits remarkable effects of the present invention is taken as an example, but the present invention is not limited to the balun transformer, and the winding wound around the drum core. Can be applied to various coil components having a two-layer structure.

1 is a schematic perspective view showing an appearance of a balun transformer 100 according to a first embodiment of the present invention. 1 is a schematic sectional view of a balun transformer 100. FIG. It is the approximate bottom view which looked at the balun transformer 100 from the mounting surface side. It is a schematic diagram for demonstrating the connection relation of the wires 131-133 and the terminal electrodes 141-146. 2 is an equivalent circuit diagram of the balun transformer 100. FIG. It is a schematic sectional drawing of the balun transformer of a comparative example. It is a figure which shows the wiring pattern on the printed circuit board for mounting the balun transformer. 6 is a schematic diagram for explaining a method of manufacturing the balun transformer 100. FIG. It is a schematic sectional drawing of the balun transformer 200 by the 2nd Embodiment of this invention. It is the approximate bottom view which looked at the balun transformer 200 from the mounting surface side. 6 is a schematic diagram for explaining a method of manufacturing the balun transformer 200. FIG. It is the substantially bottom view which looked at the balun transformer 300 by the 3rd Embodiment of this invention from the mounting surface side.

Explanation of symbols

100, 200, 300 Balun transformer 110 Drum-type core 111 Winding core portion 112 One flange portion 113 The other flange portion 120 Plate-shaped cores 131 to 133 Wire 131a to 133a One end 131b to 133b The other end 141 to 146 of the wire Electrode 150 Mounting area 151-154 Land pattern 160 Heater chip L11, L12 Primary winding L21, L22 Secondary winding CT Center tap GND Ground terminal GNDL Ground wiring P Primary side terminal PL Unbalanced transmission line ST Secondary side positive electrode Terminal SB Secondary negative terminal STL, SBL Balanced transmission line

Claims (2)

A method for manufacturing a coil component, wherein the coil component is:
A drum core having a winding core and a pair of flanges provided at both ends of the winding core;
A plurality of terminal electrodes provided on the collar;
A plurality of windings wound around the core portion and connected at both ends to the terminal electrode;
The plurality of windings are wound around the core portion and both ends are connected to the terminal electrode, and both ends and a center tap are connected to the terminal electrode. Including secondary winding,
The secondary winding includes a first wire from one end to the center tap, and a second wire from the other end to the center tap,
The first wire and the second wire are wound around the core in a state along each other,
Either one of the primary winding and the secondary winding is wound on the outer peripheral side of the core portion,
Either one of the primary winding and the secondary winding is wound on the inner peripheral side of the core portion,
The area of the terminal electrode connected to the winding wound on the inner peripheral side is at least larger than the area of the terminal electrode connected to the winding wound on the outer peripheral side,
The manufacturing method of the coil component is as follows:
A first connecting step of connecting any one of the primary winding and the secondary winding;
A second connecting step of connecting one of the primary winding and the secondary winding,
The first connecting step includes a step of thermocompression bonding one end and the other end of the winding to a terminal electrode having a relatively large area among the plurality of terminal electrodes,
The second connecting step includes a step of thermocompression bonding one end and the other end of the winding to a terminal electrode having a relatively small area among the plurality of terminal electrodes. Method. A method for manufacturing a coil component, wherein the coil component is:
A drum core having a winding core and a pair of flanges provided at both ends of the winding core;
A plurality of terminal electrodes provided on the collar;
A plurality of windings wound around the core portion and connected at both ends to the terminal electrode;
The plurality of terminal electrodes are provided on the one flange part and are arranged in this order when viewed from one direction, and the other terminal electrode is provided on the other flange part and viewed from the one direction. Including fourth to sixth terminal electrodes arranged in order,
The plurality of windings are wound around the core portion and both ends are connected to the terminal electrode, and both ends and a center tap are connected to the terminal electrode. Including secondary winding,
The secondary winding includes a first wire from one end to the center tap, and a second wire from the other end to the center tap,
The first wire and the second wire are wound around the core in a state along each other,
The area of the first terminal electrode is larger than the areas of the second and third terminal electrodes,
The area of the fourth terminal electrode is larger than the areas of the fifth and sixth terminal electrodes,
The primary winding is wound on the inner peripheral side of the core portion,
The one end of the primary winding is connected to the first terminal electrode;
The other end of the primary winding is connected to the fourth terminal electrode;
The secondary winding is wound on the outer peripheral side of the core portion,
The one end of the secondary winding is connected to the third terminal electrode;
The other end of the secondary winding is connected to the sixth terminal electrode;
Of the center tap of the secondary winding, a portion belonging to the first wire is connected to the fifth terminal electrode, and a portion belonging to the second wire is connected to the second terminal electrode. And
The manufacturing method of the coil component is as follows:
Thermocompression bonding one end of the primary winding to the first terminal electrode;
Winding the primary winding around the core;
Thermocompression bonding the other end of the primary winding to the fourth terminal electrode;
Thermocompression bonding one end of the first wire and one end of the second wire to the third and second terminal electrodes, respectively.
Winding the first wire and the second wire on the upper layer of the primary winding wound around the core portion in a state along each other;
A step of thermocompression bonding the other end of the first wire and the other end of the second wire to the fifth and sixth terminal electrodes, respectively.

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