JP2016207811A - Surface-mounting transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further attain downsizing/reduction in height and to also improve a mounting strength while securing an insulation quality regarding an EE type surface-mounting transformer.SOLUTION: Each of substantially E-shaped cores 20A and 20B includes a pair of side legs 22 and 24, a middle leg 26 and a connection part. A bobbin includes a winding core part, flanges 46 and 46' in both ends of the winding core, and fitting bases 48 and 48' on which a terminal is provided. Both side faces of the fitting bases 48 and 48' are recessed from the side legs 22 and 24 in a view from an upper side of a mounting surface. At a lower side of the side legs 22 and 24, a space 66 is formed while displacing positions of the legs of the cores 20A and 20B in such a manner that a height of the side legs 22 and 24 relative to the mounting surface becomes greater than a height of the middle leg 26 relative to the mounting surface. On the side faces, a bundling terminal ta is provided so as to be settled within a core size, thereby securing an insulation distance between the bundling terminal ta after coil connection and the side legs 22 and 24.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a small-sized transformer for surface mounting used in electronic equipment, and more specifically, to miniaturization / low profile and ensuring insulation and mounting strength.

  Regarding the EE core type transformer, it is difficult to reduce the size of the EE core type transformer while ensuring insulation. For example, in Patent Document 1 below, a convex portion is formed at the center of the thick portion having a terminal formed at the end portion of the flange, and the inner end portion of the convex portion is formed to protrude toward the winding drum portion side, The radial dimension of the inner end portion is formed to be substantially equal to the thickness of the primary coil wound around the winding body portion, and the lower outer surface of the convex portion is directed outward from the lower surface of the thick portion. An inclined taper surface is formed, cutouts for leading lines are formed on both sides of the convex part, and a primary coil is wound between the inner end parts arranged to face each other, and the leading lines are cut into the predetermined cutouts. An insulating tape larger than the coil winding width is wound around the outer periphery, and the periphery of the insulating tape runs on the outer surface on the taper of the convex portion and extends toward the outside of the thick portion, and the insulating tape The lead wire of the secondary coil wound in the shape was drawn to the outside through the predetermined notch Type transformer is disclosed.

  Further, in Patent Document 2 below, in a small transformer core in which a central leg, left and right legs, and a yoke part are integrally formed of a ferrite material, left and right legs extending from both ends in the long side direction of the yoke part, A central leg extending in parallel with the central leg, and the central leg is long in the long side direction of the yoke portion and has a thickness that is sufficiently smaller than the width in the short side direction. There has been disclosed a small transformer core characterized in that at least one surface of the corresponding leg surface bulges in a curved shape in the direction of the outside of the leg.

Japanese Patent No. 3533780 JP-A-2-244606

  However, in the technique described in Patent Document 1 described above, since the orientation of the mounting terminal is different from the orientation of the middle leg core, the curled terminal (binding terminal) cannot be within the core size, and the size is reduced. I can't. Further, if the grounding area of the mounting terminal is increased in order to ensure mounting strength, it is necessary to shift the bobbin and the curled terminal to the outside, and it is difficult to reduce the size from this point. Further, in the technique described in Patent Document 2, the lateral direction is reduced by increasing the longitudinal direction of the core of the middle leg portion, so that it is equivalent to the core of the side leg portion with the winding wound around the middle leg portion. In the case of the height, the winding portion of the middle leg portion becomes high and cannot be reduced in height. Thus, in the background art mentioned above, since the size is increased in the axial direction of the middle leg, there is a limit to downsizing.

  The present invention pays attention to the above points. A surface mount transformer for an EE type transformer is further reduced in size and height as compared with the conventional structure and has high mounting strength while ensuring insulation. The purpose is to provide

  The surface mounting transformer of the present invention includes a pair of side legs and a pair of substantially E-shaped cores connected at one end to a middle leg disposed between the pair of side legs, and a hollow into which the middle leg is inserted. A core portion, a flange portion provided at both ends of the core portion, and a mounting base that is a part of the flange portion and extends in the axial direction of the middle leg portion and is provided with a terminal. A bobbin, and both ends of the mounting base are recessed from the pair of side leg portions of the core when viewed from above the mounting surface, and the height of the side leg portion with respect to the mounting surface is high. However, the positions of the side legs and the middle legs are shifted so as to be higher than the height of the middle legs with respect to the mounting surface, and a space is formed below the side legs.

  One of the main forms is that the mounting base is provided with a mounting terminal, a binding terminal of the winding, and a groove portion for drawing out the winding, and a direction in which the mounting terminal and the binding terminal are pulled out. It is characterized by being different. One of the other forms is characterized in that the mounting terminal and the binding terminal are respectively arranged on different surfaces of the mounting base.

  In still another embodiment, the mounting terminal is pulled out in the same direction as the axial direction of the middle leg of the core, and the binding terminal is connected to both ends of the mounting base in the axial direction. It is provided so as to extend in a substantially orthogonal direction. One of the other forms is that, when viewed from above the mounting surface, the binding terminal is within the region of the projection area facing the mounting surface of the side leg portion on the upper side. It is characterized in that the length of the bent terminal is set.

  In another embodiment, a winding is wound around the core portion with the middle leg portion inserted, and the height of the winding portion is equal to the height of the side leg portion opposite to the mounting surface. Then, the winding portion on the mounting surface side is separated from the mounting surface. The above and other objects and advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.

  According to the present invention, the pair of side legs and the middle leg disposed between the pair of substantially E-shaped cores connected at one end side, and the hollow winding core into which the middle leg is inserted. A bobbin comprising a portion, a flange provided at both ends of the winding core, and a mounting base that is a part of the flange and extends in the axial direction of the middle leg and is provided with a terminal. In the surface mounting transformer provided, both ends of the mounting base are recessed from the pair of side leg portions of the core when viewed from above the mounting surface. Further, by shifting the position of the side leg and the middle leg so that the height of the side leg with respect to the mounting surface is higher than the height of the middle leg with respect to the mounting surface, A space was formed below the part. For this reason, an insulation distance can be ensured between the binding terminal after the winding connection provided on the mounting base and the side leg portion of the core. Moreover, the insulation distance of the mounting terminal provided in the said mounting base and the center leg part of the said core is securable. This makes it possible to reduce the size and height of the transformer while ensuring insulation. Also, the mounting strength can be improved by increasing the grounding area with the mounting substrate, such as increasing the number of mounting terminals.

It is a figure which shows the transformer of Example 1 of this invention, and is a perspective view which shows the state which inserted the core of the bobbin, without showing a coil | winding. (A) is a plan view of FIG. 1 as viewed from the direction of arrow F1a, (B) is a bottom view of (A) as viewed from the direction of arrow F1b, and (C) is a view of (A) from the direction of arrow F1c. Side view (D) is a side view of (A) seen from the direction of arrow F1d. It is a figure which shows the E-type core of the said Example 1, (A) is a perspective view, (B) is the side view which looked at the said (A) from the arrow F3a direction, (C) is the said (A) arrow F3b A side view seen from the direction, (D) is a side view seen from the direction of arrow F3c. It is a figure which shows the bobbin of the said Example 1, (A) is a perspective view, (B) is a side view which looked at the said (A) from the arrow F4 direction, (C) is said (A) from the mounting surface side. FIG. It is a figure which shows the terminal provided in the attachment base of the bobbin of the said Example 1, (A) is a top view of the conductor for terminals embedded in the said attachment base, (B) sees (A) from the arrow F5b direction. (C) is a side view of (A) seen from the direction of arrow F5a. It is a figure which shows the other Example of this invention.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on examples.

  First, Embodiment 1 of the present invention will be described with reference to FIGS. The present invention relates to a small surface mount transformer used in, for example, a DC / DC converter, a DC / AC inverter, and the like. FIG. 1 is a diagram illustrating the transformer according to the first embodiment, and is a perspective view illustrating a state where a core is inserted into a bobbin without showing a winding. 2A is a plan view of FIG. 1 viewed from the direction of arrow F1a, FIG. 2B is a bottom view of FIG. 1 viewed from the direction of arrow F1b, and FIG. (D) is a side view of FIG. 1 viewed from the direction of arrow F1d. FIG. 3 is a view showing the core of the present embodiment, (A) is a perspective view, and (B) to (D) are side views of (A) as viewed from the directions of arrows F3a to F3c, respectively. 4A and 4B are views showing the bobbin of the present embodiment, where FIG. 4A is a perspective view seen from above the mounting surface, FIG. 4B is a side view seen from the direction of arrow F4, and FIG. FIG. 3 is a perspective view of (A) as viewed from the mounting surface side. 5A and 5B are diagrams showing terminal conductors provided on the mounting base of the present embodiment. FIG. 5A is a plan view of the terminal conductors, and FIG. 5B is a side view of FIG. 5A viewed from the direction of arrow F5b. FIGS. 2C and 2C are side views of FIG. 1A viewed from the direction of arrow F5a.

  As shown in FIG. 1, a surface mount transformer (hereinafter referred to as “transformer”) 10 of this embodiment is formed by winding a pair of substantially E-shaped cores 20A and 20B, a bobbin 40, and windings 14 and 16. The winding portion 12 (see FIG. 2). The winding 14 forms a primary coil, and the winding 16 forms a secondary coil, and an insulating sheet 15 is provided between them (see FIG. 2A). As shown in FIG. 3 (A), the core 20A includes a pair of side legs 22, 24, a middle leg 26 disposed therebetween, and one end of the side legs 22, 24 and the middle leg 26. It is formed in a substantially E shape by a connecting portion 28 that connects the sides. As shown in FIGS. 3 (A) and 3 (B), the side legs 22 and 24 have a substantially rectangular cross section, and their short sides are substantially parallel to the mounting surface 90 (see FIG. 2 (C)). It has become. Further, the middle leg portion 26 also has a substantially rectangular cross section, and its long side is substantially parallel to the mounting surface 90.

  In this embodiment, the positions of the leg portions are shifted so that the bottom surface height of the side leg portions 22 and 24 with respect to the mounting surface 90 is higher than the height of the bottom surface of the middle leg portion 26 with respect to the mounting surface 90. Is formed. As a result, as shown in FIG. 2 (C), an insulation distance d3 from the upper end of the winding after winding is secured to the binding terminal ta on the bobbin 40 side, which will be described later, below the side legs 22 and 24. be able to. As shown in FIG. 3 (C), the connecting portion 28 is formed with a recess 30 on the top surface 28A and on the bottom surface 28B so as to match the positional deviation between the side leg portions 22, 24 and the middle leg portion 26. A convex portion 32 is formed. In addition, what is necessary is just to form the said recessed part 30 as needed so that it may mention later.

  The other core 20B has the same structure as the core 20A. These cores 20A and 20B are inserted into a hollow portion 44 of a bobbin 40, which will be described later, so that the end portions of the middle leg portion 26 face each other, and the EE type transformer 10 is formed. The cores 20 </ b> A and 20 </ b> B as described above can be formed using a material having a high magnetic permeability such as a Mn—Zn material. Alternatively, a ferrite-based material (such as Ni-Zn) other than Mn-Zn, a dust-based material, or an amorphous material may be used.

  Next, the structure of the bobbin 40 will be described with reference to FIGS. The bobbin 40 includes a core part 42 in which a hollow part 44 into which the middle leg part 26 of the core 20A, 20B is inserted is formed, and a pair of flange parts 46, 46 'provided at both ends of the core part 42. Is formed. A part of the flange portions 46 and 46 ′ is extended in the axial direction of the middle leg portion 26 inserted into the hollow portion 44, and has a thickness for providing mounting terminals tb and tc and a binding terminal ta to be described later. A mounting base 48, 48 'is constructed. When mounting on an electronic device or the like, the mounting bases 48 and 48 ′ are disposed on the mounting surface 90 side, and the mounting terminals tb (or tc) are mounted on the substrate by soldering or the like. Such a bobbin 40 is formed of, for example, a thermoplastic liquid crystal polymer (LCP), polyphenylene sulfide (PPS), thermosetting phenol resin (PF), polyurethane (PUR), diallyl phthalate resin, or the like.

  In the present embodiment, the outer periphery of the winding core portion 42 and the cross section of the hollow portion 44 are horizontally long and substantially rectangular like the middle leg portion 26 of the cores 20A and 20B. The outer portions of the flange portions 46 and 46 'are also substantially rectangular. As shown in FIG. 4 (A), the mounting base 48 is a portion obtained by extending a part of the flange portion 46 (on the mounting surface 90 side) in the axial direction of the hollow portion 44 to be thick. A concave portion is formed on the upper surface 48A along the line of the bottom surface 28B of the connecting portion 28 of the cores 20A, 20B. Further, as shown in FIG. 2 (C), both ends of the mounting base 48 are more distant than the pair of side legs 22 and 24 of the cores 20A and 20B when viewed from above the mounting surface 90. A space 66 is formed below the side legs 22 and 24 at a position that is recessed by β.

  FIG. 5 shows terminal conductors 54 provided on the mounting bases 48, 48 ′. As shown in FIG. 5A, the terminal conductor 54 is substantially F-shaped in a plan view, and includes lead-out portions 56, 58, and 60. As shown in FIG. 4B, the terminal conductor 54 has an end portion of the lead portion 56 exposed from the side surface 48D (or 48F) of the mounting base 48, and the end portions of the lead portions 58 and 60. Is embedded in the mounting base 48 so as to be exposed from the side surface 48C of the mounting base 48. A portion exposed from the side surface 48D (or 48F) of the mounting base 48 becomes a binding terminal ta for connecting the end portions 14A, 14B, 16A, 16B of the windings 14, 16. As shown in FIG. 4B, the binding terminal ta extends in a direction substantially orthogonal to the axial direction of the hollow portion 44 and substantially parallel to the mounting surface 90. Further, as shown in FIG. 2 (C), the length is set so as to be within the region of the projection area toward the mounting surface 90 of the side legs 22 and 24 when viewed from above the mounting surface 90. ing.

  On the other hand, the lead-out portions 58 and 60 are exposed on the surface from the mounting base side surface 48C and are folded back toward the bottom surface 48B of the mounting base 48 (FIGS. 1 and 5C). The portions bent along the bottom surface 48B become mounting terminals tb and tc. That is, the lead-out portions 58 and 60 are formed so as to be substantially J-shaped when FIG. 5A is viewed from the direction of the arrow F5a. As described above, in the present embodiment, the binding terminal ta and the mounting terminals tb and tc are provided on the surfaces (side surface 48C and side surface 48D or side surface 48C and side surface 48F) different from each other by 90 ° of the mounting bases 48 and 48 ′. Has been placed. The terminal conductor 54 is formed of, for example, a copper alloy.

  Such terminal conductors 54 are provided on both end sides of the mounting bases 48 and 48 '. Further, grooves 50 for pulling out the ends of the windings 14 and 16 are formed on the bottom surfaces 48B of the mounting bases 48 and 48 'toward both ends. The mounting bases 48 and 48 'have a symmetrical configuration. In this embodiment, as shown in FIGS. 1, 2B and 4C, one mounting base 48 is provided. Convex portions 52A and 52B are provided on the bottom surface 48B of '. When connecting the end portions on the winding end side of the windings 14 and 16 to the binding terminal ta, the windings 14 and 16 pass between the convex portions 52A and 52B and the mounting base 48 ′, It becomes hard to sag. In addition, if the primary and secondary directions are combined, the direction of the winding can be visually confirmed.

  By inserting the middle leg portions 26 of the cores 20A and 20B from both ends of the hollow portion 44 of the bobbin 40 having the above-described configuration, the cores 20A and 20B are inserted into the bobbin 40 as shown in FIGS. It is attached to. Then, the winding wire 14 constituting the primary coil and the winding wire 16 constituting the secondary coil are wound around the core portion 42 of the bobbin 40, and the end portions 14 </ b> A, 14 </ b> B, 16 </ b> A, 16 </ b> B are along the groove 50. The transformer 10 of the present embodiment is formed by pulling out and connecting to the binding terminal ta (see FIG. 2B). At this time, in this embodiment, since the binding terminal ta is provided in the space 66, the positions of the side leg portions 22 and 24 and the middle leg portion 26 are not shifted in the vertical direction of the mounting surface 90. The distance d2 to the binding terminal ta is larger than the distance (distance (d1) from the bottom surface of the middle leg portion 26 to the binding terminal ta in FIG. 2C). For this reason, the insulation distance d3 between the upper end of the winding after connecting the windings 14 and 16 to the binding terminal ta and the side legs 22 and 24 of the cores 20A and 20B can be secured. Further, since the mounting bases 48 and 48 ′ are interposed between the mounting terminals tb and tc and the middle leg part 26, an insulation distance between the mounting terminals tb and tc and the middle leg part 26 can be secured. Therefore, it is possible to prevent a short circuit.

  Further, the windings 14 and 16 are wound around the winding core portion 42, and the height of the winding portion 12 from the mounting surface 90 is equal to the height of the side leg portions 22 and 24 from the mounting surface 90. 2D (see FIG. 2C), the dimensions and positions of each part are set so that the winding part 12 is separated from the mounting surface 90 as shown in FIG. Can be turned upside down. The transformer 10 formed as described above is mounted by connecting the mounting terminals tb and tc to the mounting surface 90 with solder or the like. At this time, the mounting strength is mechanically increased by using the two mounting terminals tb and tc.

Thus, according to the first embodiment, there are the following effects.
(1) A pair of substantially E-shaped cores 20A and 20B in which a pair of side leg portions 22 and 24 and a middle leg portion 26 disposed therebetween are connected at one end side, and the middle leg portion 26 are inserted. A hollow core portion 42, flange portions 46, 46 'provided at both ends of the core portion 42, and a part of the flange portions 46, 46' in the axial direction of the middle leg portion 26. In the surface mounting transformer 10 including the bobbin 40 including the mounting bases 48 and 48 'that are extended and provided with terminals, both ends 48D and 48F of the mounting bases 48 and 48' are viewed from above the mounting surface. So that the height of the side legs of the core with respect to the mounting surface is higher than the height of the middle legs with respect to the mounting surface. The legs of the cores 20A and 20B are shifted so that a space is provided below the side legs 22 and 24. 6 to the formation. In addition, the binding terminals ta are provided on the side surfaces 48D and 48F of the mounting bases 48 and 48 '. For this reason, the insulation distance d3 can be secured between the binding terminal ta after the windings 14 and 16 are connected and the side leg portions 22 and 24. In addition, since the mounting bases 48 and 48 'are interposed between the mounting terminals tb and tc and the middle leg portion 26, an insulation distance can be secured. For this reason, a short circuit can be prevented.

(2) Since a short circuit can be prevented, a core material with high magnetic permeability that requires insulation can be used, and high inductance can be obtained with the same size, leading to improved characteristics.
(3) By shifting the positions of the side legs 22 and 24 and the middle legs 26 of the cores 20A and 20B with respect to the mounting surface 90, the surface areas of the cores 20A and 20B are increased, and heat dissipation is improved.
(4) By setting the binding terminal ta to a length that is not exposed from the side leg portions 22 and 24, the transformer 10 can be made equal to the core size and the size can be reduced. In addition, since the substrate area can be further reduced by downsizing, the material cost can be reduced.
(5) When the windings 14 and 16 are wound around the winding core portion 42 and the height of the winding portion 12 is equal to the height of the side leg portions 22 and 24, the winding portion 12 is Since the height can be optimized to be separated from the mounting surface 90, the height can be reduced.
(6) By providing the two mounting terminals tb and tc on one terminal conductor 54, the grounding area with the mounting surface 90 increases, and the mounting strength can be improved.

In addition, this invention is not limited to the Example mentioned above, A various change can be added in the range which does not deviate from the summary of this invention. For example, the following are also included.
(1) The shapes and dimensions shown in the above-described embodiments are merely examples, and can be appropriately changed within a range where similar effects can be obtained. For example, as in the example shown in FIGS. 6A-1 and 6A-2, the middle leg portion 26A may have a substantially elliptical cross section. In the above embodiment, the cost is reduced by providing the recess 30 on the upper surface 28A of the connecting portion 28. However, the upper surface 28A has a flat shape as shown in FIG. 6B. It is not something that prevents you. Further, as in the example shown in FIG. 6C-1, all of the side leg portions 72 and 74 and the middle leg portion 76 of the core 70 may have a substantially circular cross section. In the illustrated example, the radius of the middle leg portion 76 is approximately √2 times the radius of the side leg portions 72 and 74 so that the cross-sectional area is equivalent to the example shown in FIG. Is set to Further, the core portion 102 of the bobbin 100 has a substantially square shape matching the outer shape of the middle leg portion 76. In addition, the upper surface 112 of the mounting base 110 of the bobbin 100 is appropriately formed with a slope or a curved surface so as to follow the shape of the connecting portion 78 of the core 70.

  Further, the shape of the terminal conductor 120 is also changed as shown in the drawing in accordance with the shape of the concave upper surface 112. In the illustrated example, the exposed portion of the mounting terminal tb is shorter than the exposed portion of the other mounting terminal tc, and the exposed positions of the mounting terminals tb and tc are lower than the binding terminal ta. Note that the example shown in FIG. 6C-1 is also an example, and the substantially F-shaped terminal conductor shown in the first embodiment may be used. Further, as in the example shown in FIG. 6 (C-2), the core portion 104 of the bobbin 100 may be substantially circular according to the diameter of the middle leg portion 76. Further, as in the example shown in FIG. 6D, curved surfaces 82 and 84 are provided on the inner side of the side legs 22 and 24 of the cores 20A and 20B along the outer peripheral surface of the winding portion 12. Also good. Further, as in the example shown in FIG. 6 (E), curved surfaces 82 and 84 are provided on the side leg portions 22 and 24, an elliptical shape is used as the core portion 42A, and the core portion 42A is further used. The middle leg portion 26B inserted into the can also be formed in an oval shape. Of course, the example shown in FIG. 6 is also an example, and the design can be changed as appropriate within a range where the same effects as those of the first embodiment can be obtained.

(2) The terminal conductor 54 shown in the above embodiment is also an example, and may be changed as appropriate. For example, in the first embodiment, two mounting terminals tb and tc are provided on one terminal conductor 54. However, this is also an example, and the number of mounting terminals and the grounding area of the mounting terminals may be increased or decreased as necessary. It's okay. Further, when a plurality of mounting terminals are provided, any one mounting terminal may be used, or any two or more of three or more mounting terminals may be used. Moreover, in the said Example, although the conductor 54 for terminals was substantially J type in the side view, this is also an example and can be suitably changed as needed.
(3) The materials of the cores 20A and 20B, the bobbins 40, the windings 14 and 16, and the terminal conductor 54 shown in the above-described embodiment are also examples, and various known materials are used within the range where similar effects can be obtained. It's okay.
(4) The winding order of the windings shown in the above embodiment is also an example, and the primary and secondary winding orders are not limited. Further, the primary and secondary windings may be alternately layered. The insulating sheet 15 may be provided as necessary, and the winding itself may be covered. Alternatively, a protective tape may be wound around the winding surface.
(5) In the above embodiment, for example, a transformer mounted on a DC / DC converter, a DC / AC inverter or the like has been described as an example. However, the present invention is not limited to this, and the present invention is reduced in size and height. It can be applied as a transformer for various known electronic devices that are required.

  According to the present invention, the pair of side legs and the middle leg disposed between the pair of substantially E-shaped cores connected at one end side, and the hollow winding core into which the middle leg is inserted. A bobbin comprising a portion, a flange provided at both ends of the winding core, and a mounting base that is a part of the flange and extends in the axial direction of the middle leg and is provided with a terminal. In the surface mounting transformer provided, both ends of the mounting base are recessed more than the pair of side leg portions of the core when viewed from above the mounting surface, and the height of the side leg portion with respect to the mounting surface is high. However, the height of the leg is shifted so as to be higher than the height of the middle leg with respect to the mounting surface, and a space is formed below the side leg. For this reason, it is possible to reduce the size and height while ensuring insulation between the terminal provided on the mounting base and the core, and therefore, it can be applied to the use of a small transformer for surface mounting. In particular, since the mounting strength can be improved by increasing the grounding area with the mounting substrate, such as increasing the number of mounting terminals, it is suitable for transformers for applications that require mounting strength, such as for mobile devices, small communication devices, and in-vehicle applications. Is preferred.

10: Transformer for surface mounting 12: Winding part 14, 16: Winding 14A, 14B, 16A, 16B: End part 15: Insulating sheet 20A, 20B: Core 22, 24: Side leg part 22A, 24A: Upper surface 22B, 24B: Bottom surface 26, 26A, 26B: Middle leg portion 28: Connection portion 28A: Top surface 28B: Bottom surface 30: Concave portion 32: Convex portion 40: Bobbin 42, 42A: Core portion 44: Hollow portion 46, 46 ': Gutter 48: Mounting base 48A: Upper surface 48B: Bottom surface 48C to 48F: Side surface 50: Grooves 52A, 52B: Protrusions 54, 54A: Terminal conductors 56, 56A, 58, 58A, 60, 60A: Lead portion 66: Space 70: Core 72, 74: Side leg 76: Middle leg 78: Connection part 80, 80A: Core 82, 84: Curved surface 90: Mounting surface 100: Bobbin 102, 104: Core portion 110: Mounting base 112: Upper surface 12 : Terminal conductor ta: binding terminal tb, tc: mounting terminal

Claims (6)

A pair of substantially E-shaped cores, in which a pair of side legs and a middle leg disposed between them are connected at one end;
A hollow core part for inserting the middle leg part, a flange part provided at both ends of the core part, a part of the collar part and extending in the axial direction of the middle leg part A bobbin comprising a mounting base provided with
With
Both ends of the mounting base are recessed from the pair of side leg portions of the core when viewed from above the mounting surface, and
The positions of the side legs and the middle legs are shifted so that the height of the side legs with respect to the mounting surface is higher than the height of the middle legs with respect to the mounting surface, and a space is provided below the side legs. Surface mount transformer characterized by forming The mounting base is provided with a mounting terminal, a binding terminal of a winding, and a groove for drawing out the winding,
The surface-mounting transformer according to claim 1, wherein the mounting terminals and the binding terminals are drawn in different directions.   The surface-mounting transformer according to claim 2, wherein the mounting terminal and the binding terminal are respectively disposed on different surfaces of the mounting base. The mounting terminal withdrawing direction is the same direction as the axial direction of the middle leg portion of the core,
4. The surface-mounting transformer according to claim 2, wherein the binding terminals are provided at both end portions of the mounting base so as to extend in a direction substantially orthogonal to the axial direction. When viewed from above the mounting surface,
5. The surface-mounting transformer according to claim 4, wherein the binding terminal is accommodated in a region of a projection region facing the mounting surface of the side leg portion on the upper side.   When the winding is wound around the winding core portion into which the middle leg portion is inserted and the height of the winding portion becomes equal to the height of the side leg portion on the opposite side to the mounting surface, the mounting surface side The surface mount transformer according to claim 1, wherein the winding portion is spaced apart from the mounting surface.

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