JP2008066672A - Substrate incorporating thin magnetic component, and switching power supply module employing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate incorporating a thin magnetic component, and to provide a switching power supply module employing it. <P>SOLUTION: The substrate incorporating a thin magnetic component comprises a thin magnetic component having slit-shaped grooves provided in the front and back of a magnetic substrate, a through hole connecting the grooves in the front and back, a first conductor provided in the slit-shaped groove in the first major surface of the magnetic substrate, a second conductor provided in the groove in the second major surface, a connection conductor provided in the through hole, and a coil conductor formed of the first conductor, the second conductor and the connection conductor, and two insulator sheets on which a conductor pattern is formed wherein the thin magnetic component is arranged between the two insulator sheets and a portion of the coil conductor in the thin magnetic component is connected with a portion of the conductor pattern on the insulator sheet through a via hole. The switching power supply module comprises a substrate and a power supply IC wherein via holes are provided in the substrate to connect the front and back electrically, and the power IC is connected with the substrate incorporating a thin magnetic component through an electrode pattern provided on the first major surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thin magnetic component built-in substrate, a switching power supply chip and a switching power supply module using the same. This thin magnetic component built-in substrate is useful for a small power converter such as a DC-DC converter.

  In recent years, electronic information devices, in particular, various portable electronic information devices have been widely used. Many of these electronic information devices use a battery as a power source, and incorporate a power conversion device such as a DC-DC converter. Usually, this power conversion device is a substrate such as a printed circuit board made of ceramic substrate, resin, etc. with active elements such as switching elements, rectifier elements, control ICs, and individual components of passive elements such as magnetic components, capacitors, resistors, etc. A hybrid power supply module mounted on is used.

  Various electronic information devices including the above-mentioned portable devices are required to be small, thin, and light. With this demand, there is a strong demand for miniaturization, thinness, and lightness of the built-in power conversion device. Miniaturization of the hybrid power supply module has been advanced by technologies such as MCM (multi-chip module) technology and multilayer ceramic component technology. However, since the hybrid-type small power module is mounted by arranging individual components on the same substrate, reduction of the mounting area of the power module is limited. In particular, magnetic parts such as inductors and transformers have a very large volume compared to an integrated circuit, which is the biggest restriction in reducing the size and thickness of electronic parts.

There are two possible future directions for miniaturization and thinning of these magnetic components: a chip component that is as small and thin as possible and a surface-mounting direction, and a thin film formation on a silicon substrate.
As a surface mounting direction, in recent years, an example in which a thin micromagnetic element (coil, transformer, etc.) is mounted on a semiconductor substrate by applying semiconductor technology has been reported.

  As a planar magnetic component, a planar magnetic component (thin inductor) in which a thin film coil is sandwiched between a magnetic substrate and a ferrite substrate on the surface of a semiconductor substrate on which semiconductor components such as a switching element and a control circuit are mounted is obtained by thin film technology. What was formed is proposed (for example, refer patent document 1). This makes it possible to reduce the thickness of the magnetic element and reduce its mounting area.

In addition, as a direction of incorporating the coil in the board, a core member is combined with the opening of the circuit board, and a secondary coil and a primary coil are mounted between the core and the circuit board or a counterbore part of the circuit board, A coil device that can be made thin is disclosed (see Patent Documents 2 and 3).
Similarly, a structure in which a core member is combined with an opening of a circuit board and a coil pattern is formed on a laminated board is also commercially available.

JP 2001-196542 A JP-A-5-55048 JP-A-7-283029

  However, in the method described in Patent Document 1, it is necessary to increase the number of turns of the thin-film coil in order to obtain a large inductance. If the number of turns is increased, the DC superimposition characteristic deteriorates. Both characteristics could not be satisfied.

  In addition, the coil devices described in Patent Documents 2 and 3 and the above-described commercially available products require an extremely large area in order to ensure thinness and satisfy both the inductance and the DC superposition characteristics. However, it has been inevitably limited to a certain thickness, and it has not been possible to make the thickness 10 mm or less.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a thin magnetic component built-in substrate that satisfies both inductance and DC superimposition characteristics and can reduce the thickness and mounting area of a magnetic element, and a switching power supply module using the same. .

  That is, the thin magnetic component-embedded substrate of the present invention is provided with slit-like grooves on the front and back sides of the magnetic substrate, and further with through-holes connecting the slit-like grooves on the front and back sides. The first conductor is provided in the slit groove on the main surface, the second conductor is provided in the slit groove on the other surface (second main surface) of the magnetic substrate, the connection conductor is provided in the through-hole, A thin magnetic component in which a coil conductor is formed by one conductor, a second conductor, and a connection conductor, and two insulating sheets on which a conductor pattern is formed, and the thin magnetic component is disposed between two insulating sheets. In addition, a part of the coil conductor of the thin magnetic component and a part of the conductor pattern of the insulator sheet are connected through a via hole (through hole).

  The switching power supply module of the present invention includes the thin magnetic component built-in substrate and a power supply IC, and is provided with via holes for electrically connecting the front and back surfaces of the thin magnetic component built-in substrate, and a part of the thin magnetic component An electrode pattern including an electrode pattern connected to a part of the conductor pattern connected to the substrate and an electrode pattern connected to a via hole that electrically connects the front and back surfaces of the magnetic component built-in substrate is the first electrode pattern. The power supply IC is provided on the main surface and is connected to the thin magnetic component built-in substrate through an electrode pattern.

  Another switching power supply module according to the present invention is characterized in that a power supply IC, a capacitor, and a chip resistor are connected to an insulating sheet-like conductor pattern of the thin magnetic component built-in substrate.

According to the present invention, it is possible to provide a thin magnetic component built-in substrate that satisfies both the inductance and the DC superimposition characteristics and can reduce the thickness of the magnetic element and reduce the mounting area. It can be made ultra-thin.
Further, the effective area of the magnetic substrate can be increased by providing the TH (through hole) terminal portion outside the magnetic substrate.
For switching power supplies of the class of 10 W or more, using a thin magnetic component built-in substrate of about several centimeters to several tens of centimeters, a power IC, a capacitor, and a chip resistor on a conductor pattern such as a wiring circuit A switching power supply in which components such as the above are mounted can be provided, and the switching power supply can be made thinner and smaller than the conventional one.

  1, 2, and 3 are main part configuration diagrams of one embodiment of a thin magnetic component used in the thin magnetic component-embedded substrate of the present invention. FIG. 1 is a plan view of a principal part of a thin magnetic component seen through from above, where a solid line indicates a first conductor provided on the first main surface, and a broken line indicates a second conductor and a through hole provided on a second main body. The connection conductor provided inside is shown. 2 is a cross-sectional view of a main part cut along a line XX 'in FIG. 1, and FIG. 3 is a cross-sectional view of a main part cut along a line YY' in FIG. FIG. 4 is a production process cross-sectional view (corresponding to a cross-sectional view of the thin magnetic part cut along the line YY ′ in FIG. 1) showing a production process which is one embodiment of the method of manufacturing a thin magnetic part used in the present invention. .

As shown in FIG. 1, a plurality of slit-shaped grooves arranged in parallel with each other are provided on one surface (first main surface) of the magnetic substrate 1. Each one of the outer slit-like grooves extends to near the end of the magnetic substrate, and an electrode recess for forming a coil electrode is formed at the tip of the extended slit-like groove.
Through holes connected to the second main surface are provided at all ends other than the ends connected to the recesses where the coil electrodes of the respective slit-like grooves are formed. A through hole is also provided in the central portion of the recess where the coil electrode is formed.
The second main surface is provided with slit-like grooves that run obliquely in parallel with each other so as to connect the two through holes.
A coil electrode 5a is provided in the electrode recess on the first main surface, and the first conductor 2 is filled in the slit-like groove. The slit-shaped groove on the second main surface is filled with the second conductor 3, and the through-hole is filled with the connection conductor 4.
As shown in these drawings, a coil is formed by the first conductor 2, the second conductor 3, and the connection conductor 4, and coil electrodes 5a are provided at both ends thereof.
It is preferable that an IC chip corresponding electrode 5b is also provided on the first main surface.

The magnetic substrate 1 is composed of a sintered body of magnetic powder, and examples of the magnetic powder include NiZn ferrite, Co ferrite, CoZn ferrite, Mg ferrite, and composite ferrite containing these as main components.
The first conductor 2, the second conductor 3, the connection conductor 4, and the coil electrode 5a are preferably made of a conductive metal, and examples of the conductive metal include Cu, Ag, Au, and Pt.

The upper surfaces of the first conductor 2 and the second conductor 3 coil electrode 5a are preferably at the same height as the surface of the magnetic substrate 1.
That is, it is preferable that the first main surface, the first conductor 2, and the upper surface of the coil electrode 5a form the same plane, and the second main surface and the upper surface of the second conductor 3 form the same plane.

  In this thin magnetic component, the first main surface, the second main surface, and all the side surfaces are covered with an insulating sheet. Wiring and electrode patterns are formed on both surfaces of the insulating sheet covering the first main surface and the insulating sheet covering the second main surface, and these two sheets are printed wiring boards. These wiring boards are provided with through holes, and the conductors of the front and back substrates can be electrically connected by copper plating or a conductive filling agent.

  A part of the coil conductor of the thin magnetic part and a part of the conductor pattern of the insulator sheet are connected via a via hole. A through hole is provided in the insulator sheet on the side wall so as to connect the two printed wiring boards, and an electrode corresponding recess is provided at a position corresponding to the through hole of the two printed wiring boards. And the electrode corresponding | compatible recessed part is filled with a conductor, and the electrode and the wiring connected to this are formed.

Next, a manufacturing method of the thin magnetic component and the thin magnetic component built-in substrate will be described.
FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a thin magnetic component.
The magnetic substrate of the magnetic component shown in FIGS. 1 to 3 is obtained by firing a green sheet containing magnetic powder and resin.
As the resin contained in the green sheet, any resin that is usually used as a binder for magnetic particles can be used. Examples thereof include polyvinyl butyral, polyvinyl alcohol, cellulose resin, and acrylic resin.
The mixing ratio of magnetic particles and resin is preferably 70 to 90% by volume of magnetic particles.

A green sheet is an unsintered sheet, in which magnetic particles and a resin are mixed using a solvent or a dispersion medium, defoamed, and formed into a sheet having a predetermined thickness by a sheet forming method such as a doctor blade method. It was dried at an appropriate temperature according to the type. Examples of the solvent and dispersion medium include mineral oil solvents, alcohols, organic solvents such as acetone and toluene, and water.
The thickness of the green sheet is preferably 20 to 1000 μm after drying. When the thickness is less than the above lower limit, it becomes difficult to handle the sheet. When the thickness exceeds the upper limit, the thickness of the magnetic component itself is increased. Therefore, it cannot be a thin magnetic component.

The through hole provided in the green sheet may be circular, square, or any other shape. The cross-sectional area of the through hole is preferably 100 to 100,000 μm ² . When the cross-sectional area is less than the above lower limit, drilling is difficult, and the power loss of the thin magnetic component is increased. On the other hand, when the above upper limit is exceeded, the magnetic component becomes large and it is difficult to make it a small magnetic component.
Slit grooves are provided on both the front and back sides of the green sheet.
The through hole may be formed by punching with a mold, may be formed by sandblasting, or may be formed by laser processing using a CO ₂ laser or the like.
The formation of through-holes and slit-like grooves (hereinafter collectively referred to as “drilling”) has been conventionally performed on a magnetic substrate such as a ferrite substrate. There was a problem such as taking. However, when drilling a green sheet as in the present invention, since the green sheet is flexible, there are no cracks due to handling, and no through-holes are generated, so that through holes can be formed with a high yield.

The magnetic substrate is formed by firing a green sheet and sintering magnetic particles, but it may be obtained by firing one green sheet, or firing a laminate formed by laminating a plurality of green sheets. You may have done. The number of stacked layers can be 2-20.
When the magnetic substrate is a fired green sheet laminate, the green sheet is drilled in each green sheet before lamination so that the through holes are located at the same position. The required number of sheets may be laminated, or the green sheet laminate may be perforated, or two or three green sheets may be bonded together, then perforated, and a plurality of the perforated green sheet laminates may be passed through. May be laminated so that they are at the same position.
Lamination may be performed by temporarily pressing with a hot press and then laminating and pressing with a method such as warm isostatic pressing (WIP) or hot pressing. The pressure of WIP is preferably 10 to 1000 MPa, and the temperature is preferably 40 to 90 ° C.

  When the magnetic substrate is obtained by firing a laminate of green sheets, the slit-like grooves are preferably provided only in the outermost layer of the laminate, and when the laminate is composed of three or more green sheets, From the point of easiness, as shown in FIGS. 4 (b-1), (b-2), and (c), the slit-like groove is provided through the outermost green sheet, and the second sheet from the outside is provided. It is preferable that the surface of the green sheet forms the bottom of the slit-like groove. As shown in FIG. 4C, the green sheet of the inner layer of the laminate is provided with through holes that connect slit-like grooves provided in both outermost layers. When the laminate consists of two green sheets, the slit-shaped groove does not penetrate the outermost layer, and its bottom is provided at the middle position in the thickness direction of the outermost layer, and the slit provided in both outermost layers The groove-like grooves are connected by through holes provided at predetermined positions.

  For the formation of the first conductor and the second conductor, first, an adhesion layer and a plating seed layer can be formed on the front surface of the magnetic substrate by sputtering, for example. The adhesion layer is a layer for adhering the magnetic substrate and the plating seed layer. For example, Ti, Cr, W, Nb, Ta, or the like can be used. Cu, Ni, Au, or the like can be used as the plating seed layer. The plating seed layer may be formed by a sputtering method, a vacuum deposition method, a CVD (chemical vapor deposition) method, a combination of a sputtering method and an electroless plating method, or may be formed only by an electroless plating method.

Next, a conductor layer is formed by, for example, electrolytic plating. At this time, as shown in FIG. 4E, conductors are also plated on the front and back surfaces of the substrate, in the slit-like grooves, and in the through holes 8.
Next, by polishing the front and back surfaces of the magnetic substrate and removing the conductor layers other than the slit-shaped grooves on the front and back surfaces, as shown in FIG. One conductor, a second conductor in the slit-like groove on the second main surface, and a connection conductor in the through-hole can be formed, and a solenoid-like coil pattern can be formed by the first conductor, the connection conductor, and the second conductor. . At the same time, an electrode pattern can be formed.
The coil conductor and the electrode surface are preferably plated with Ni or Au as necessary to form a surface treatment layer. When this plating is performed, it is performed after polishing.

Next, an example of the manufacturing method of the thin magnetic component built-in substrate of the present invention will be described.
FIG. 5 is a cross-sectional view showing an example of the manufacturing process of the thin magnetic component built-in substrate, and is a cross-sectional view corresponding to the ZZ ′ cross section of FIG.

First, a thin magnetic component is soldered to a printed circuit board on which wiring and electrode patterns are formed on both sides (FIG. 5A). When the fixing is insufficient, the thin magnetic component and the printed wiring board may be bonded with a commercially available underfill agent.
Separately, a resin substrate is prepared in which a portion into which a thin magnetic component is to be inserted is punched. This substrate is provided with through holes, conductor plating is applied to the surface of the through holes, the through holes are filled with a conductive filler, and the front and back substrates (when the thin magnetic substrate is built-in, the first of the thin magnetic substrate is filled). The conductors of the printed wiring board facing the first main surface and the printed wiring board facing the second main surface) can be electrically connected.

  As shown in FIG. 5 (b), a resin substrate having a thin magnetic component placed in the hole is fitted on the printed wiring on which the thin magnetic component is soldered, and as shown in FIG. 5 (c). A thin printed circuit board with a built-in magnetic component as shown in FIG. 5 (d) can be manufactured by covering and bonding a printed wiring board thereon.

  A switching power supply chip can be obtained by connecting the power supply IC chip 9 to the IC chip corresponding electrode pattern (electrode 5b) formed on the first main surface of the thin magnetic part of the thin magnetic part built-in substrate. For connection between the power IC chip 9 and the IC chip corresponding electrode 5b, for example, the stud bump 10 is formed on the electrode (pad) of the power IC chip 9, and the stud bump 10 is joined to the IC chip corresponding electrode 5b of the thin magnetic component. The method can be adopted. This bonding may be ultrasonic bonding, solder bonding, or bonding with a conductive adhesive. Furthermore, it is preferable to strengthen the fixation between the power supply IC chip 9 and the thin magnetic component using a sealing material such as an underfill material or an epoxy resin. These are used to fix each element and prevent the occurrence of malfunctions caused by the influence of moisture, etc., and to obtain long-term reliability, but do not affect the initial characteristics of the power converter. It is desirable to strengthen the fixation for long-term reliability. Finally, for example, by using a dicer, the switching power supply chip as shown in FIG. 6 can be obtained by dividing the chip into individual chips composed of a power supply IC and a thin magnetic component. Furthermore, by joining a multilayer ceramic capacitor array or the like to the surface opposite to the mounting surface of the power IC chip of the thin magnetic component, for example, an ultra-small and ultra-thin power conversion device having a thickness of 4 mm and a weight of 15 g can be obtained. Obtainable.

  A switching power supply module can be obtained by providing at least a power supply IC, a chip capacitor, and a resistor on the front and back surfaces of the thin magnetic component built-in substrate. Other components that may be disposed on the front and back surfaces of the thin magnetic component-embedded substrate include filter components.

(Example 1)
FIG. 4 is a diagram showing the manufacturing process of Example 1, and is a cross-sectional view of the main part corresponding to the YY ′ cross section of FIG. 1 in each manufacturing process. FIG. 4 is an enlarged view of only one chip portion, but in actuality, it was manufactured as a substrate on which a large number of such chips were formed.

(Green sheet production process)
First, Ni—Zn ferrite calcined powder was used as a ferrite raw material powder, butyral resin (polyvinyl butyral) was mixed as a binder, toluene was mixed as a solvent, and the mixture was defoamed to prepare a slurry. . The mixing ratio of ferrite and resin was 75% by volume of ferrite.
Using this slurry, a sheet was formed by the doctor blade method. The blade interval and sheet drawing speed of the doctor blade were adjusted so that the thickness of the green sheet after drying was 100 μm. The sheet was dried as it was at 60 ° C., and punched out to produce a green sheet 7 (FIG. 4A). The outer shape punching was performed with a mold in consideration of shrinkage due to firing.

(Drilling / slit processing)
The slit grooves and electrode recesses were formed using a die composed of a punch and a die. Ten slit-shaped grooves on the first main surface were formed at intervals of 0.20 mm with dimensions of 0.20 × 2.0 mm. However, as shown in FIG. 1, one end of the groove at both ends was extended by 0.30 mm, and a recess for electrode of 0.2 × 0.4 mm was formed at the tip. The through hole was formed on a green sheet other than both outer sides, that is, a green sheet forming an inner layer, using a die composed of a 0.15 × 0.15 mm punch and die. As shown in FIG. 1, slit grooves having a width of 0.20 mm that run obliquely in parallel with each other were formed on the second main surface as shown in FIG.

(Lamination process)
Next, four green sheets having through holes are sandwiched between the green sheet for the first main surface and the green sheet for the second main surface, and the positions are set so that the through holes are firmly overlapped with respect to the two through holes. The samples were temporarily bonded using a hot press. Then, lamination pressure bonding was performed with a warm isostatic press (WIP). The WIP temperature was 80 ° C. and the pressure was 15 MPa to produce a bonded green sheet 7b. A cross-sectional view of the bonded green sheet 7b is shown in FIG.

(Baking process)
The bonded green sheet 7b was fired. Firing was performed using an electric furnace from room temperature to 400 ° C. for 5 hours, from 400 ° C. to 500 ° C. for 6 hours, and from 500 ° C. to 900 ° C. over 4 hours. The temperature was maintained at 900 ° C. for 2 hours, furnace-cooled to 500 ° C. over 1 hour, and then furnace-cooled to room temperature over time. By this firing, the resin content of the green sheet was decomposed and volatilized to obtain a magnetic substrate 1 made of ferrite having a square shape of 100 × 100 mm and a thickness of 480 μm. A sectional view of this magnetic substrate is shown in FIG.

(Coil conductor formation process)
The obtained magnetic substrate was washed with pure water to remove dust adhering to the surface, and then Ti / Cu was formed on the entire surface of the magnetic substrate 1 by a sputtering method to form a plating seed layer. At this time, the plating seed layer was formed not only on the front and back surfaces of the substrate but also on the slit groove surface and the wall surface of the through hole 8.
Next, a Cu layer was formed by electrolytic plating. At this time, as shown in FIG. 4E, Cu was plated also on the front and back surfaces of the substrate, in the slit-like grooves, and in the through holes 8.
Next, by polishing the front and back surfaces of the magnetic substrate and removing the Cu layer at portions other than the slit-shaped grooves on the front and back surfaces, as shown in FIG. One conductor, a second conductor in the slit-like groove on the second main surface, and a connection conductor in the through hole were formed, and a solenoid-like coil pattern was formed by the first conductor, the connection conductor, and the second conductor. At the same time, an electrode pattern was formed.
A surface treatment layer was formed by electroless plating of Au on the coil conductor and the electrode surface.

  In this way, slit-like grooves and through holes are formed on the front and back surfaces of the magnetic substrate, the first conductor is in the slit-like groove on the first main surface of the magnetic substrate, and the second is in the slit-like groove on the second main surface. A thin magnetic component was produced in which a conductor was provided, a connection conductor was provided in the through hole, and a coil conductor was formed by the first conductor, the second conductor, and the connection conductor.

  Further, the thin magnetic component obtained above was soldered to a printed circuit board on which wiring and electrode patterns were formed on both surfaces (FIG. 5A).

  Separately, a resin substrate was prepared in which a portion into which a thin magnetic component was inserted was punched by a die punch. In addition, through holes are formed in this substrate by punching with a mold, Cu plating is applied to the surface of the through holes, and the through holes are filled with a Tg paste as a conductive filling agent, and built-in thin magnetic components When the substrate is completed, the printed circuit board facing the first main surface of the thin magnetic substrate can be electrically connected to the printed circuit board facing the second main surface. .

  As shown in FIG. 5 (b), a resin substrate with a thin magnetic component placed on the printed wiring on which the thin magnetic component is soldered is fitted so that the thin magnetic component fits in the hole. A resin for filling a hole was injected into the gap, and as shown in FIG. 5C, the resin was filled with a lid with a printed wiring board to cure the hole filling resin, and the printed board was bonded to a thin magnetic component and a resin board. In this way, a thin magnetic component built-in substrate as shown in FIGS.

  The obtained thin magnetic component built-in substrate is disposed between two insulating sheets on which a thin magnetic component forms a conductor pattern such as a wiring circuit, and a part of the coil conductor of the thin magnetic component and the conductor pattern of the insulator sheet A part of was connected via a via hole. Moreover, it was confirmed that the obtained thin magnetic component built-in substrate had a predetermined inductance value.

(Example 2)
Using the thin magnetic component built-in substrate produced in Example 1, stud bumps 10 are formed on the electrodes (pads) of the power supply IC chip 9, and the stud bumps 10 are used as the first main thin magnetic components of the thin magnetic component built-in substrate. The IC chip corresponding electrode pattern (electrode 5b) formed on the surface was connected by ultrasonic bonding. Next, the fixing of the power supply IC chip 9 and the thin magnetic component was reinforced with the underfill 11, and a switching power supply chip whose cross-sectional schematic diagram is shown in FIG.
Furthermore, a multilayer ceramic capacitor array or the like was joined to the surface (second main surface) opposite to the power IC chip mounting surface of the thin magnetic component to produce a thin power converter having a thickness of 4 mm and a weight of 15 g.

(Example 3)
Using the thin magnetic component built-in substrate produced in Example 1, a power supply IC, a chip capacitor, and a resistor were arranged on the front and back surfaces of the substrate to produce a DC-DC switching power supply module with an output capacity of 100 W. Various components such as a chip resistor, a chip capacitor, and a power supply IC were mounted by soldering on the electrode pattern (electrode 5b) of the thin magnetic component built-in substrate on which wiring patterns, electrode patterns (electrodes 5b), and solder resists were formed on the front and back surfaces. . FIG. 7 is a perspective view of the switching power supply manufactured in this manner, and FIG. For reference, a perspective view of a conventional switching power supply is shown in FIG. 9 and a cross-sectional image diagram is shown in FIG. In the figure, 14 is a magnetic component, and 15 is a chip component. The perspective view of FIG. 7 is different from FIG. 9 in that the magnetic parts do not appear on the surface.
The manufactured DC-DC switching power supply was able to reduce the thickness to 80% and the area to 70% with respect to the smallest of the conventional switching power supplies.

  In this switching power supply, even when the solder reflow was performed at 300 ° C., no peeling or floating occurred between the internal magnetic component and the resin substrate. Furthermore, 1000 heat cycle tests at −25 ° C. to 150 ° C. were carried out, but there was no significant change in the characteristics, and reliability as a switching power supply could be ensured.

  According to the present invention, it is possible to provide a magnetic component that is smaller, thinner, and more reliable than a conventional one that can be used in a small power converter.

The principal part top view of one Embodiment of the thin magnetic component by the manufacturing method of this invention XX 'sectional view of an essential part of one embodiment of a thin magnetic component manufactured by the manufacturing method of the present invention Cross-sectional view of main part YY ′ of one embodiment of thin magnetic component by manufacturing method of the present invention Sectional drawing which shows the manufacturing process of the thin magnetic component used for this invention Sectional drawing which shows the manufacture process of the board | substrate with a thin magnetic component of one embodiment of this invention Sectional drawing of thin magnetic component built-in substrate and IC chip of one embodiment of the present invention A perspective view of a switching power supply using a thin magnetic substrate. Cross-sectional view of a switching power supply using a thin magnetic substrate A perspective view of a conventional switching power supply Sectional view of a conventional switching power supply

Explanation of symbols

1: Magnetic substrate 2: First conductor 3: Second conductor 4: Connection conductor 5: Electrode 5a: Coil electrode 5b: Electrode for IC chip 6: Resin sheet 7: Green sheet
7a: Green sheet with through hole 7b: Bonded green sheet with through hole 8: Through hole 9: IC chip 10: Stud bump 11: Underfill 12: Filling resin 13: Slit groove 14: Magnetic component 15: Chip component

Claims (4)

  A slit-like groove is provided on each of the front and back sides of the magnetic substrate, and a through hole is provided to connect the slit-like grooves on the front and back sides. The first conductor is placed in the slit-like groove on one surface (first main surface) of the magnetic substrate. Provided, a second conductor is provided in a slit-like groove on the other surface (second main surface) of the magnetic substrate, a connection conductor is provided in the through hole, and the first conductor, the second conductor, and the connection conductor are coil conductors. And two insulating sheets on which a conductor pattern is formed. The thin magnetic component is disposed between two insulating sheets, and a part of the coil conductor of the thin magnetic component A thin magnetic component built-in substrate, wherein a part of a conductor pattern of an insulating sheet is connected via a via hole.   2. The thin magnetic component built-in substrate according to claim 1, wherein the magnetic substrate is a ferrite substrate.   3. The thin magnetic component-embedded substrate according to claim 1 and a power supply IC, wherein via holes for electrically connecting the front and back surfaces of the thin magnetic component-embedded substrate are provided and connected to a part of the thin magnetic component. An electrode pattern including an electrode pattern connected to a part of the conductive pattern and an electrode pattern connected to a via hole for electrically connecting the front and back surfaces of the magnetic component built-in substrate is provided on the first main surface. A switching power supply module, wherein a power supply IC and the thin magnetic component built-in substrate are connected via an electrode pattern.   A switching power supply module, wherein a power supply IC, a chip capacitor, and a resistor are connected to the insulating sheet-like conductor pattern of the thin magnetic component built-in substrate according to claim 1.

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