JP2006253394A - Chip-like winding-type coil component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip-like winding-type coil component which is superior in a Q characteristic, has high connection reliability, and is suitable for miniaturization. <P>SOLUTION: In the winding-type coil component 10, ends of windings 6 are bonded to electrodes 5 arranged on sides S at lower sides of corner brims 2a and 2b of a drum-type ferrite core 3 having the square corner brims 2a and 2b on both ends of a winding core 1. An outer periphery of the winding 6 wound to the winding core 1 is coated with magnetic powder content coating resin 8. Recessed grooves 4 are made on the sides S at the lower sides of the corner brims 2a and 2b from a winding core 1-side to an end face F in a thickness direction of the brims. First electrodes 5 are formed in the widthwise direction including the recessed groove 4 on the sides S on the lower sides where the recessed grooves 4 of the corner brims 2a and 2b are arranged. The ends of winding 6 are thermocompression-bonded at the side toward the end face F in the groove 4, and a part near the winding core 1 in the recessed groove 4 at the end of winding 6 is coated with coating resin 8. A surface of coating resin 8 in the recessed groove 4, an outer surface of a thermocompression bonding part C, and a surface of the first electrode 5, are coated by a second electrode 9 of conductive resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention belongs to the technical field of chip-like wound coil components having an electrode structure directly attached to the core.

  2. Description of the Related Art Conventionally, as one form of a chip-shaped wound coil component used for a signal system, there is a wound chip inductor 20 having an internal structure and an external appearance as shown in a partial sectional view of FIG.

  The winding chip inductor 20 shown in FIG. 7 has a winding 24 wound around a drum type ferrite core 23 having square corners 22 at both ends of a winding core 21, and the lower side of the figure is an electrode on the mounting surface side. This is a basic structure in which a frame lead 25 that is soldered is molded with an exterior resin 26.

  In the structure described above, the frame lead 25 is disposed outside the drum-type ferrite core 23 for the high Q (reactance X and resistance R: Quality factor) characteristic required for the signal system inductor. The eddy current loss is suppressed by separating as much as possible.

  However, along with the downsizing of electronic devices, the above-described surface-mount type chip-like wound coil components mounted on a substrate are also required to be further miniaturized. 25 is placed on the end face side of the square ridge 22 and is molded with the exterior resin 26 so as to wrap the whole, so that the portion covered with the resin around the drum type ferrite core 23 (black solid in FIG. There is a demerit in that the shape becomes inevitably larger.

  Therefore, from the viewpoint of miniaturization, recently, from the form of the electrode structure by the frame lead 25 of the winding chip inductor 20 shown in the schematic diagram of FIG. 8A, the schematic diagram of FIG. As shown in the internal structure diagram of the coiled coil component 30 shown in the figure, directly attached electrodes 29 are formed on the end faces and side faces of the square flanges 22a and 22b of the drum type ferrite core 23 without using the frame lead 25 (core Directly mounted polyhedral electrode structure).

  As shown in the internal structure diagram of FIG. 8B, the general electrode of the core-mounted multi-surface electrode structure chip-shaped wound coil component 30 is formed by the square flanges 22a and 22b of the drum-type ferrite core 23. Many of them are formed in a cap shape over four side surfaces and five end surfaces.

  As an exception, as a publicly known document relating to an electrode structure (one-sided electrode structure) of a wound-type coil component in which an electrode is provided only on substantially one side (side to be solder-bonded to a mounting substrate) on the side surface of a square horn, the following [ Patent Document 1] describes a winding-type coil component 40 as shown in (a) side view and (b) front view of FIG. 9 as a “chip-type variable inductance element”. The column structure 3rd line to the lower left column 4th line describes the electrode structure and the mounting method on the mounting board. That is, the chip type variable inductance element 40 of FIG. 9 is provided on one side surface (bottom side) of the square hooks 32a and 32b of the drum type ferrite core 31 having the square hooks 32a and 32b provided at both ends of the core 33. Electrodes 35a and 35b are provided on the lower surfaces of the insulating layers 34a and 34b, and both ends of the coil 36 are connected to the electrodes 35a and 35b, respectively. The electrodes 35a and 35b are soldered onto a predetermined pattern (electrode pads 26a and 26b) on the mounting board (printed wiring board) 25 with solder.

JP 58-124213 A

  Regarding the wire-wound coil component 30 having the electrode 29 attached directly to the core shown in FIG. 8B, it is desirable to make the electrode area as small as possible from the viewpoint of improving the Q characteristics. As shown in the relationship between the magnetic flux (thick arrow) shown in FIG. 8B and the directly attached electrode 29 (see the magnetic flux arrow of the winding chip inductor 20 of (a) for comparison). .), The area of the electrode 29 provided on the square flanges 22a and 22b of the drum-type ferrite core 23 of the coiled coil component 30 extends over the four peripheral side surfaces and the five end surfaces of the square flanges 22a and 22b. Taking a large value causes a change in the magnetic field inside the core, causing eddy currents in a region close to the electrode surface and degrading the Q characteristics as an inductor.

  Therefore, from the viewpoint of obtaining high Q characteristics, the one-sided electrode structure of [Patent Document 1] is relatively superior. However, from the viewpoint of the reliability and mounting strength of the electrode structure, the core directly attached electrode 29 is generally the first electrode directly attached to the core made of an Ag electrode (formed by baking a silver paste containing glass frit). In general, it has a two-layer structure of a second electrode composed of a conductive resin electrode (printed and dried with a conductive Ag paste containing a curable resin), but the adhesion strength between the two is not so strong. For this reason, when the area of the electrode 29 is small, when an impact or load is applied after mounting on the substrate, electrode peeling may occur at the interface between the two and the mounting strength may be reduced. That is, the reduction of the electrode area for improving the Q characteristic (single-sided electrode structure) tends to cause electrode peeling in terms of mounting strength, leading to a decrease in reliability due to insufficient mounting strength.

  In particular, as can be seen from the detailed observation of the chip-type variable inductance element 40 of [Patent Document 1] in FIG. 9, insulating layers 34a and 34b are provided on the lower surfaces of the flanges 32a and 32b, and the steel plates are laminated on the lower surfaces. Electrodes 35a and 35b made of the above are provided (from the above, it is not an electrode directly attached to the core), and an electrode structure in which both ends of the winding 36 are extracted and connected to the electrodes 35a and 35b. It has become. Thus, when soldering to the substrate 25 with the solders 26a and 26b, there is a possibility that the connection with the winding 36 is loosened due to the heating of the soldering, or that the soldered portion of the connection part is eroded by the soldering heat. The situation is high, and it cannot be said that the mounting reliability is high. Note that the molded resin 37 does not reach the electrode region, and is simply for the purpose of protecting the winding portion and improving the magnetic permeability.

  On the other hand, the electrode structure of the electrode 30 of the wire-wound coil component 30 in FIG. 8B is such that the first electrode and the second electrode are both vertically and horizontally on the end faces of the square flanges 23a and 23b of the drum-type ferrite core 22. Since the electrode structure (five-surface electrode structure) covers the entire four circumferential surfaces, the contact area between the two is large, so even if the contact strength per unit area is low, the overall contact area As a result, it is in a situation where the standard mounting strength or more is secured.

  However, in the future, it will be important to increase the adhesion strength of the electrode while securing the mounting strength while improving the Q characteristics of the wound coil component by reducing the electrode area of the electrode directly attached to the core together with downsizing. Balancing is an issue.

  The present invention has been made in view of the above circumstances, and it is possible to obtain a high Q while realizing improvement in mounting reliability while preventing an electrode portion from being peeled off against an impact after soldering to a mounting board. An object of the present invention is to provide a chip-shaped wound coil component having an electrode structure.

The present invention
(1) The core 1 is attached to the electrode 5 provided on the lower side S of the drum-shaped ferrite core 3 provided with square-shaped corners 2a, 2b at both ends of the core 1, respectively. In the chip-like wound coil component 10 in which the ends of the wound winding 6 are joined and the outer periphery of the winding 6 wound around the winding core 1 is covered with a magnetic powder-containing exterior resin 8, the square rod 2a , 2b on at least the lower side surface S in the thickness direction of the flange from the winding core 1 side to the end surface F, and provided on the lower side surface S provided with the concave grooves 4 of the square flanges 2a, 2b. The first electrode 5 is formed in a strip shape in the width direction including the concave groove 4, and the end of the winding 6 is thermocompression bonded near the end surface F in the concave groove 4, and the end of the winding 6 is A portion near the core 1 in the groove 4 is covered with an exterior resin 8, and the surface of the exterior resin 8 in the groove 4, the surface of the thermocompression bonding portion C, and the front The above-mentioned problems are solved by providing a chip-shaped coiled coil component 10 that is covered with a second electrode 9 made of conductive resin so as to cover the surface of the first electrode 5.
(2) A groove 4 'is also provided on the other side surface of the square ridges 2a, 2b, and a cross-sectional area Sb perpendicular to the central axis of the drum-type ferrite core 3 of the exterior resin 8b entering the groove 4'. The chip according to (1), wherein the outer resin 8a entering the concave groove 4 on the lower side surface has a larger cross-sectional area Sa perpendicular to the central axis of the drum type ferrite core 3. The above-described problem is solved by providing the wound coil component 10.
(3) The chip-shaped wound coil according to (2), wherein the concave grooves 4 and 4 'are provided in the lower side surface S and the upper side surface U of the square rods 2a and 2b, respectively. By providing the component 10, the above problem is solved.

The chip-like coiled coil component according to the present invention is
(1) The eddy current loss and copper loss can be reduced while reducing the shape by the single-sided electrode structure directly attached to the core, and the Q characteristic is improved.
(2) The belt-shaped first electrode (internal electrode) and second electrode (external electrode) sandwich the thermocompression bonding portion between the first electrode at the end of the winding in the groove and in the groove Since the exterior resin that has intruded into the substrate is in close contact with each other, an electrode structure with high adhesion strength is obtained, and since the lead portion of the winding is not exposed, high connection reliability is obtained.
(3) Since the thickness of the layer of the first electrode formed on the bottom in the groove is thicker than the other part, and the cross-sectional area of the flow path into the groove of the exterior resin is small, It becomes a structure in which the exterior resin is less likely to enter than the concave groove without an electrode provided on the side surface, and the thermocompression bonding junction between the first electrode and the end of the winding is prevented from being covered with the exterior resin, Conductivity between the outer surface of the thermocompression bonding portion and the second electrode (external electrode) becomes good, and variation in DC resistance Rdc characteristics is reduced.
(4) A concave groove is provided on each of the lower side surface and the upper side surface of the four side surfaces of the square-shaped square hook at both ends of the winding core, and electrodes are formed only on the lower side surface thereof. Since the outer side resin is exposed in the state where the exterior resin has penetrated into the groove, the directionality as a coil component becomes clear in appearance, and it is easy to confirm the directionality of the surface on which the electrode is provided. It is.

  DESCRIPTION OF EMBODIMENTS Embodiments of a chip-shaped wound coil component according to the present invention will be described with reference to the drawings. In addition, about the member similar to the past, it shows with a same sign.

  FIG. 1 is a longitudinal sectional view of a wound-type coil component according to the present invention as viewed from the side. FIG. 2 is a cross-sectional structural view taken along the line AA ′ of FIG. 1 as viewed from the front side of the wound coil component according to the present invention. FIG. 3 is a cross-sectional structure taken along the line BB ′ of FIG. 1 as viewed from the front side of the wire-wound coil component according to the present invention. 4 to 6 are process flow diagrams for explaining the procedure for manufacturing the wire-wound coil component according to the present invention.

  1 to 3, a wound-type coil component 10 includes a drum-type ferrite core 3 having square corners 2a and 2b at both ends of a winding core 1, and a side surface S below the corners 2a and 2b. The end portion of the winding 6 wound around the winding core 1 is joined to the first electrode 5 provided on the outer periphery of the winding 6 and the outer periphery of the winding 6 wound around the winding core 1 is covered with a magnetic powder-containing exterior resin 8. A chip-like coiled coil component 10, in particular, concaved from the core 1 side to the end surface F in the thickness direction of the collar (left and right direction in FIG. 1) on at least the lower side surface S of the square collars 2 a and 2 b. A groove 4 is provided, and the first electrode 5 is formed in a strip shape in the width direction (left and right direction in FIG. 2) including the groove 4 on the lower side surface S where the groove 4 of the square ridges 2a and 2b is provided. The end of the winding 6 is thermocompression bonded near the end face F in the concave groove 4 and the winding in the concave groove 4 at the end of the winding 6 is wound. A portion close to 1 is covered with the magnetic powder-containing exterior resin 8 so as to cover the surface of the magnetic powder-containing exterior resin 8a in the concave groove 4, the surface of the thermocompression bonding portion C, and the surface of the first electrode 5. It has a structure covered with a second electrode 9 made of conductive resin. In addition, in FIG. 1 thru | or FIG. 3, as a preferable embodiment, the plating layer 11 (for example, Ni plating layer and Sn plating layer) is additionally formed for protection of an electrode surface.

  That is, the wound-type coil component 10 of the present invention is characterized in that the drum-type ferrite core 3 having the concave groove 4 on the lower side S of the four side surfaces of the square ridges 2a and 2b, and the concave Covers the band-shaped first electrode 5 to which the end of the winding 6 provided on the surface provided with the groove 4 is bonded, and the thermocompression bonding portion C formed near the end surface F in the concave groove 4. Without covering the drawn portion of the winding 6 near the core 1 and covering the region sandwiched between the square ridges 2a and 2b, the magnetic powder-containing exterior resin 8 as an exterior material, and the thermocompression bonding joint It has the band-like second electrode 9 that is in contact with the first electrode 5 that is opposed to sandwich the C, and realizes both high Q characteristics and mounting reliability while reducing the size of the coil component. It has a feature in that.

  Hereinafter, the manufacturing procedure will be described with reference to FIGS. 4 to 6 are all shown in a state in which the chip-shaped wound coil component 10 is turned upside down, and the lower side that is the mounting surface side of the square flanges 2a and 2b of the drum type ferrite core 3 is shown. The side surface S of the is upward.

  First, as shown in FIG. 4 (a), the lower side of the square hooks 2a and 2b of the drum type ferrite core 3 provided with square square hooks 2a and 2b at both ends of the core 1. On the side surface S and the upper side surface U, concave grooves 4, 4 ′ are provided from the core 1 side to the end surface F in the thickness direction of the flange. For example, the drum-type ferrite core 3 is formed by spray-drying a slurry containing a nickel zinc ferrite material powder having a high resistivity that enables a direct-attached electrode, a binder, and a solvent. Is obtained by means of integrally molding into a drum mold using a dry molding press, or after obtaining a flat ferrite molded body by the same method as described above and then grinding to form a drum-type ferrite shape The body is fired at 1050 ° C. for 2 hours to obtain a drum-type sintered ferrite core.

  Next, as shown in FIG. 4B, the first electrode 5 is formed in a band shape in the width direction (arrow direction) including the concave groove 4 on the lower side surface S of the square ridges 2a and 2b. The first electrode 5 is formed, for example, by applying and baking a conductive paste made of Ag or Ag—Pd. This coating and baking includes, for example, Ag conductive powder, glass frit, and a vehicle by holding the drum type ferrite core 3 on a printing stage using a screen mask having a desired opening pattern by a screen printing technique. It is formed by applying an Ag electrode material paste with a squeegee and baking at 650 ° C. for 30 minutes. In the first electrode 5 formed as described above, the thickness t1 of the bottom portion of the concave groove 4 is generally about twice as thick as the thickness t2 of other portions.

  Next, as shown in FIG. 5C, a winding 6 such as a polyurethane resin-coated copper wire is wound around the core 1 of the drum-type ferrite core 3, and the ends 6a and 6b are respectively connected to the left and right sides. Pull out into the concave grooves 4 of the square ridges 2a, 2b.

  Next, as shown in FIG. 5 (d), the end portions 6a and 6b of the winding 6 drawn out into the concave groove 4 are moved closer to the end face F in the concave groove 4 by thermocompression bonding. 5 to form a thermocompression bonding portion C.

  Next, as shown in FIG. 6 (e), the thermocompression bonding joint C formed in the concave groove 4 is exposed and is located near the core 1 at the ends 6a, 6b of the winding 6. A magnetic powder (ferrite powder) -containing resin 8 is molded that covers the outer periphery of the winding 6 wound around the winding core 1 while entering the groove 4 of the square flanges 2a and 2b so as to cover the portion. The amount of ferrite added to the magnetic powder-containing resin 8 is desirably in the range of 5 wt% to 80 wt% in order to maintain the properties of the resin. Moreover, as a resin material, the coating material which mix | blended the epoxy resin and the carboxyl group modification propylene glycol is used, for example. The mold is filled with a dispenser and left to dry at room temperature for 30 minutes and then molded, or molded with a mold.

  Next, as shown in FIG. 6F, the entire surface of the exterior resin 8 in the groove 4, the surface of the thermocompression bonding portion C, and the exposed surface of the first electrode 5 are covered. Thus, it coats with the 2nd electrode 9 of conductive resin. A silver powder-containing resin paste is used for the second electrode 9 and is applied and cured so as to completely cover the thermocompression bonding portion C on the first electrode 5 in the concave groove 4.

  Further, preferably, for the purpose of electrode protection, a Ni-plated or Sn-plated plating layer 11 is applied on the second electrode 9 as shown in FIGS. it can. However, it should be noted that when the plated layer 11 extends inside the square ridges 2a and 2b, the Q decreases due to an increase in eddy current loss. According to the inventor's experiment, it is important to keep the inward wraparound to 0.2 mm or less, preferably 0.1 mm or less.

  With the above configuration, the frame lead 25 used in the conventional chip-shaped coiled coil component 20 disappears and there is no dead space, so that the size can be reduced. Further, in order to maintain a high Q, electrodes are formed only on the lower side surface S of the square ridges 2a and 2b on the substrate mounting side to reduce eddy current loss.

  In addition, since the magnetic powder-containing resin 8 is applied and shaped, a part of the magnetic flux that has traveled to the outside can be passed through the magnetic powder-containing resin 8, and the magnetic flux penetrating the electrode can be reduced. Eddy current loss can be further reduced. Moreover, high inductance is obtained by the magnetic powder-containing resin 8.

  Thus, the number of turns can be reduced as compared with a normal winding component, and the copper loss can be reduced. The combination of these characteristic actions makes it possible to ensure high Q characteristics and high connection reliability while reducing the overall shape.

  By the way, in the above-mentioned embodiment, the concave grooves 4, 4 'are provided on the lower side surface S and the upper side surface U of the four side surfaces of the square-shaped square flanges 2a, 2b at both ends of the core 1, respectively. The electrode is formed only on the lower side S of the structure, and the upper side U is exposed while the magnetic powder-containing exterior resin 8 is intruded into the groove 4 '. Yes.

  As described above, not only the lower side surface S of the four side surfaces of the square ridges 2a and 2b but also the upper side surface U or all the four side surfaces are provided with concave grooves, so that pressure is applied when the exterior resin 8 is molded. The flow path to the concave groove as the escape route of the resin is secured, and the penetration of the exterior resin 8 into the concave groove 4 on the lower side surface S where the first electrode 5 is formed is the thermocompression bonding portion C. It is suppressed before this.

  The degree of penetration of the exterior resin 8 into the concave grooves 4 and 4 ′ is determined by the size of the cross-sectional area of the penetration path, and as can be seen from FIGS. 3 and 2, the concave grooves 4 on the lower side surface S. The opening is narrowed by the thickness of the coating film in the groove 4 of the formed first electrode 5, and the cross-sectional area Sb of the intrusion path of the groove 4 ′ on the upper side U and the recess on the lower side S are In the cross-sectional area Sa of the entry path of the groove 4, Sb> Sa, and in the recessed groove 4 ′ where the electrode is not formed, the exterior resin 8 b enters so as to almost fill the recessed groove, whereas the recessed groove where the electrode is formed In No. 4, the exterior resin 8 does not reach the thermocompression bonding portion C formed on the end face F side of the square ridges 2a and 2b.

  On the other hand, when the outer surface of the thermocompression bonding portion C is covered with the exterior resin 8, the first electrode is connected from the end portions 6a and 6b of the winding 6 through the bonding surface of the thermocompression bonding portion C. 5 and a conductive path connected to the second electrode 9 via a contact surface between the first electrode 5 and the second electrode 9, and thus the lower side surface. Variations in the degree of penetration of the exterior resin 8 into the S concave grooves 4 cause variations in the DC resistance Rdc characteristics of the obtained chip-like wound coil components.

  Thus, in the embodiment of the present invention, the outer surface of the thermocompression bonding portion C between the first electrode 5 and the end portions 6a and 6b of the winding 6 is prevented from being covered with the exterior resin 8. The outer surface of the thermocompression bonding portion C and the second electrode 9 (external electrode) are in direct contact with each other, so that the electrical conductivity is improved and the variation in the DC resistance Rdc characteristic is reduced. .

  In particular, when the concave groove 4 ′ provided on the side surface other than the lower side surface S is on the upper side surface U, the directionality as a coil component becomes clear in appearance and is in a taped state. However, it has a characteristic advantage that confirmation of the directionality of the surface provided with the electrode is easy.

It is the longitudinal cross-section structure figure seen from the side surface side of the winding type | mold coil component which concerns on this invention. It is the AA 'cross-section figure of FIG. 1 seen from the front side of the winding type | mold coil component which concerns on this invention. It is the BB 'cross-section figure of FIG. 1 seen from the front side of the winding type | mold coil component which concerns on this invention. It is a figure which shows the (a) drum type ferrite core formation process of the beginning in the process flow for demonstrating the manufacturing procedure of the winding type | mold coil component which concerns on this invention, (b) 1st electrode formation process. It is a figure which shows the (c) winding process and the (d) joining process in the process flow for demonstrating the manufacturing procedure of the winding type coil component which concerns on this invention. It is a figure which shows the (e) resin molding process and the (f) 2nd electrode formation process in the process flow for demonstrating the manufacturing procedure of the winding type coil component which concerns on this invention. It is a partial cross section figure which shows the internal structure of the conventional winding chip inductor. It is a figure which shows the relationship between the electrode structure of the conventional winding type coil components, and magnetic flux. It is (a) side view and (b) front view of the winding type coil components described in [patent document 1].

Explanation of symbols

1 Winding core 2a, 2b Square rod 3, 3 'Drum type ferrite core 4, 4' Groove
5 First electrode
6 Winding 6a, 6b End of winding
8 Magnetic powder-containing resin 8a, 8b Magnetic powder-containing resin that has entered the groove
9 Second electrode 10, 20 Chip-shaped wound coil component
11 Plating layer
F End face of square ridge Sa, Sb Cross section
S Lower side
C Thermocompression bonding

Claims (3)

Joining the ends of the winding wound around the winding core to the electrodes provided on the lower side surface of the square ferrite core provided with square-shaped square hooks at both ends of the winding core, In the chip-shaped winding type coil component in which the outer periphery of the winding wound around the winding core is coated with the magnetic powder containing exterior resin,
A groove is provided on at least the lower side surface of the square ridge in the thickness direction of the ridge from the core side to the end surface, and in the width direction including the concave groove on the lower side surface provided with the concave groove of the square ridge. The first electrode is formed in a strip shape, and the end of the winding is thermocompression bonded near the end face in the groove, and the portion near the core in the groove at the end of the winding is covered with an exterior resin. A chip-shaped coiled coil component, which is covered with a second electrode of a conductive resin so as to cover the surface of the exterior resin in the groove, the surface of the thermocompression bonding portion, and the surface of the first electrode .   A concave groove is also provided on the other side surface of the square rod, and a cross-sectional area perpendicular to the central axis of the drum type ferrite core of the exterior resin that enters the concave groove enters the concave groove on the lower side surface. 2. The chip-shaped coiled coil component according to claim 1, wherein the exterior resin is made larger than a cross-sectional area perpendicular to the central axis of the drum type ferrite core. The chip-shaped coiled coil component according to claim 2, wherein the concave groove is provided on each of a lower side surface and an upper side surface of the square hook.

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