JP2008066671A - Thin magnetic component, and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for manufacturing a small and thin magnetic component inexpensively. <P>SOLUTION: Slit-shaped grooves are provided in the front and back of a magnetic substrate and a through hole connecting the grooves in the front and back is provided, a first conductor is provided in the slit-shaped groove of a first major surface, a second conductor is provided in the slit-shaped groove of a second major surface, a connection conductor is provided in the through hole, and a coil conductor is formed of the first conductor, the second conductor and the connection conductor in a thin magnetic component. The manufacturing process of a thin magnetic component comprises a step for making slit-shaped grooves in the front and back of a green sheet containing magnetic powder and resin and boring a through hole connecting the grooves in the front and back, a step for firing the green sheet after boring/slit making step to obtain a magnetic substrate, and a step for providing first conductor in the slit-shaped groove of a first major surface, a second conductor in the slit-shaped groove of a second major surface, a connection conductor in the through hole of the magnetic substrate and forming a coil conductor of the first conductor, the second conductor and the connection conductor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thin magnetic component and a method for manufacturing the same. This magnetic component 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. In recent years, there have been reports of examples in which thin micromagnetic elements (coils, transformers, etc.) are mounted on a semiconductor substrate by applying semiconductor technology.

  In particular, 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 switching elements and control circuits are mounted is a thin film. What was formed by the technique 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. However, the formation of the thin conductor by the thin film technology is performed by using a vacuum process, and the production by this vacuum process increases the cost. Further, when used in a place with a large current, a large number of laminations of a magnetic film and an insulating film are required, and there is a problem that the cost becomes very high.

  Further, as a planar magnetic element, there has been proposed one in which a resin in which magnetic particles are mixed in a space between spiral (spiral) coil conductors is sandwiched between two ferrite substrates ( For example, see Patent Document 2.) In this method, since the inductance of the coil conductor is substantially proportional to the number of spirals (turns), it is necessary to increase the number of turns in order to obtain a large inductance. In order to increase the number of turns without increasing the mounting area, it is necessary to reduce the cross-sectional area of the coil conductor. That is, in order to obtain a large inductance, it is necessary to reduce the cross-sectional area of the coil conductor and increase the conductor wire length. However, if the coil cross-sectional area is reduced and the conductor wire length is increased, the DC resistance of the coil conductor is increased, resulting in an increase in power loss.

  As a method of solving such problems, reducing the DC resistance of the coil conductor and suppressing power loss, a magnetic insulating substrate, a first conductor formed on the first main surface of the magnetic insulating substrate, and the magnetic insulating substrate A thin-film magnetic induction element comprising a solenoidal coil conductor that connects a second conductor formed on the second main surface of the first conductor and a connecting conductor formed in a through-hole penetrating the magnetic insulating substrate. Yes (see Patent Document 3). In the proposed embodiment, through holes are formed in the ferrite substrate, conductive layers are formed on the inner surface of the through hole, the first main surface, and the second main surface, and electrode patterns are formed on both main surfaces to form a conductor coil. Forming. The conductive coil is formed by forming a resist pattern having a predetermined shape and generating a plating layer in the opening.

In addition, as in the method of manufacturing a multilayer inductor element, a green sheet (meaning an unprocessed sheet, in the case of a ferrite substrate, a mixture of a fine powder of a component that becomes ferrite by ferrite or heat treatment (firing) and a binder made of resin is used. There is also a method in which a conductive paste containing a conductor such as Ag powder is formed on a sheet in advance by screen printing, and a connection conductor is formed simultaneously with the firing of the green sheet.

Further, in the Si semiconductor process and the like, a process called a copper damascene process has been put into practical use in recent years (see, for example, Patent Document 4). In this process, a recess is formed in the insulating layer in advance, a metal thin film is formed on the entire surface of the insulating layer including the inside of the recess, for example, by plating, and then, for example, by a polishing method such as chemical mechanical polishing (CMP). This process is called a damascene process, in which the metal thin film on the surface of the insulating layer other than the recesses is removed to leave the metal thin film only in the recesses, thereby filling the recesses with the metal thin film.
In particular, a process in which only a groove for forming a wiring is formed as a recess and the recess is filled with a metal thin film to form a wiring is called a single damascene process. A process of forming both a plug and a wiring by forming a plug forming hole as a recess in the bottom of the groove in addition to the wiring forming groove is called a dual damascene process.
JP 2001-196542 A JP 2002-233140 A (FIG. 1) JP 2004-274004 A JP 2000-331991 A

However, the method described in Patent Document 3 requires a large number of through holes. For example, three through holes are required for three turns, and seven are required for four turns and (number of turns) × 2-1 through holes.
Conventionally, such a through hole has been formed on a sintered ferrite substrate by any one of laser processing, sand blast processing, electric discharge processing, ultrasonic processing, and mechanical processing. However, in any of the methods, the processing time, the processing size, and the like are greatly restricted, and a ferrite substrate having a large number of fine through holes cannot be manufactured at a low cost with a high yield.

The fired ferrite substrate is hard and fragile, making it difficult to form a through hole and making it impossible to increase the processing speed. Therefore, since processing time is required, the cost cannot be reduced. Further, it was not possible to drill holes with a micro diameter of 100 μmφ or less or holes with a large aspect ratio (depth / hole diameter). In addition, defects such as tapering due to a large difference in hole diameter between the processing introduction side and the outlet side were also observed.
For example, sandblasting is suitable for providing a large number of minute through holes of about 0.13 mmφ on a ferrite fired substrate having a thickness of about 500 μm. However, in sandblasting, it is necessary to use fine sand to form micropores, the drilling speed is very slow, and it takes about 30 minutes on one side (drilling up to half). In addition, there was a hole clogging due to sand entering, and the yield was also poor.

  Also, in the photo process, it is necessary to form a mask film in which the pattern of the through-hole part is formed. In the photo process, it is easy to form a taper. There were many man-hours. In addition, there is a problem that a yield is low because cracks occur when the jig is attached to and detached from the jig.

  In addition, in the method of forming the connection conductor at the same time as the green sheet is fired, such as the method of manufacturing the multilayer inductance element, the electric resistance of the coil conductor is large, and the direct current resistance as a magnetic component is increased. There was a problem of ending up. In order to reduce the power loss, it is necessary to increase the cross-sectional area of the coil conductor or shorten the length of the conductor wire, and there is a problem that a large inductance cannot be formed in a small and thin shape.

  Further, in the method of forming a coil conductor by pattern plating as described in Patent Document 3, from the viewpoint of ensuring a high yield and productivity, the ratio of the resist pattern pattern interval (line interval) to the resist thickness is 1: 1. However, the resist thickness could not be made larger than the line interval. Also, with pattern plating, it is not possible to plate to a thickness greater than the resist thickness, and therefore, the plating thickness cannot also be greater than the line spacing, so the coil conductor is formed in a fine pattern. When it is, the cross-sectional area of the coil is small, and it is difficult to reduce the power loss.

The damascene process is used for forming a wiring of a semiconductor circuit, in particular, a Si process, and is a process developed for forming a wiring pattern up to several μm order.
On the other hand, in the production of the coil conductor, it is necessary to produce a wiring with a width of several tens to several hundreds of μm. When a damascene process is applied to a ceramic substrate, fine processing of the ceramic material, plating, A new process adapted to the damascene process, such as polishing after plating, is necessary, and it has been difficult to form such a coil conductor on a ceramic substrate by the damascene process using the conventional technology.

In view of such circumstances, an object of the present invention is to provide a method for manufacturing a small and thin magnetic component at low cost.
That is, the thin magnetic component of the present invention is provided with slit-like grooves on the front and back sides of the magnetic substrate, and further with a through hole connecting the slit-like grooves on the front and back sides, and one surface (first main surface) of the magnetic substrate. The first conductor is provided in the slit-shaped groove, the second conductor is provided in the slit-shaped groove on the other surface (second main surface) of the magnetic substrate, the connection conductor is provided in the through hole, and the first conductor and A coil conductor is formed by the second conductor and the connection conductor.

  The thin magnetic component manufacturing method of the present invention includes a drilling / slit processing step in which a slit-like groove is formed on the front and back of a green sheet containing magnetic powder and resin, and a through-hole that connects the slit-like groove on the front and back is provided. , A firing step of firing the green sheet after the drilling / slit processing step to obtain a magnetic substrate, and providing a first conductor in a slit-like groove formed on one surface (first main surface) of the magnetic substrate, A conductor forming step in which a second conductor is provided on the other surface (second main surface) of the magnetic substrate, a connection conductor is provided in the through hole of the magnetic substrate, and a coil conductor is formed by the first conductor, the second conductor, and the connection conductor. It is characterized by having.

When the magnetic component of the present invention is used, it is possible to provide a small and thin magnetic element with low power loss due to excellent dimensional accuracy and low electrical resistance.
Further, according to the manufacturing method of the present invention, it is possible to manufacture a small and thin magnetic component with low dimensional accuracy and low power loss because it has excellent dimensional accuracy without much time, and particularly with high yield. Even a fine pattern can secure a necessary coil cross-sectional area and can be manufactured with good dimensional accuracy and yield.

1, 2, and 3 are main part configuration diagrams of one embodiment of the thin magnetic component of the present invention.
1 is a plan view of a principal part of a thin magnetic component seen through from above, FIG. 2 is a sectional view of the principal part cut along line XX ′ in FIG. 1, and FIG. 3 is a line YY ′ in FIG. It is principal part sectional drawing cut | disconnected by. FIG. 7 is a production process cross-sectional view showing a production process which is an embodiment of the method for producing a thin magnetic part of the present invention. Although FIG. 7 shows an enlarged view of only one chip portion, actually, it is manufactured as a substrate on which a large number of such chips are formed.

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 5 are provided at both ends thereof.

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.
The first conductor 2 and the first main surface in the vicinity thereof are covered with a protective film 6 except for the coil electrode portion. The second conductor 3 and the second main surface in the vicinity thereof are also covered with the protective film 6.
As the protective film 6, an insulating material such as an epoxy resin, an acrylic resin, or a polyimide resin is used.

An IC chip-corresponding electrode 5b may be provided on the first main surface. When this IC chip-corresponding electrode 5b is provided, the first main surface that is not covered with the protective film 6 as with the coil electrode 5a. Provided on top.
This magnetic component is useful as a component for a small power converter such as a DC-DC converter.

Next, the manufacturing method of the thin magnetic component of the present invention will be described.
FIG. 4 is a manufacturing process flow showing one embodiment of the method of manufacturing a thin magnetic component of the present invention.
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.
In the present invention, any resin that is usually used as a binder for magnetic particles can be used as the resin, and 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. 7 (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 groove. As shown in FIG. 7C, the green sheet of the inner layer of the laminate is provided with through holes that connect the 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. 7E, 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 layer in 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 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.

As shown in FIG. 7F, it is preferable to form a protective film 6 on the surface of the magnetic substrate on which the coil conductor and the electrode are formed. By this protective film, it is possible to prevent generation of scratches on the coil pattern in a later process, and it is possible to protect from conductive dust, foreign matter, and unnecessary solder.
This protective film may be formed by attaching a film-like insulating material, or a liquid insulating material may be used, for example, a pattern formed by screen printing or the like, and then cured. After forming the protective layer, electroless plating of Ni and Au may be performed only on the surface of the electrode 5. This is because metal protective conductors such as the above-described surface treatment layer and electroless plating layer on the surface of the electrode 5 are used to obtain a stable connection state in an IC connection step in a later step.
In this way, a substrate on which many thin magnetic components as shown in FIG. 1 are formed is produced.

  Next, the power supply IC chip 9 is connected to the electrode 5 of the thin magnetic component. That is, the stud bump 10 is formed on the electrode pad of the IC chip 9 and the stud bump 10 is joined to the electrode 5 of the thin magnetic component. Examples of the bonding method include ultrasonic bonding, solder bonding, and bonding using a conductive adhesive. If necessary, the IC chip 9 and the thin magnetic component may be reinforced with a sealing material such as underfill 11 or epoxy resin. These reinforcements are used to fix each element and prevent malfunctions caused by the effects of moisture, etc., and to obtain long-term reliability, and do not affect the initial characteristics of the power converter, These reinforcements are preferably performed in order to obtain long-term reliability.

Finally, a dicer is used to divide the chip into individual chips made of IC and thin magnetic parts.
Through the steps described above, a small and thin power conversion device on which a power supply IC and a thin magnetic component as shown in FIG. 8 are mounted can be manufactured.
Furthermore, by bonding a multilayer ceramic capacitor array or the like to the surface opposite to the IC chip mounting surface, it is possible to form an ultra-small and long-thin power converter.

When the through hole is fine or when a through hole with higher dimensional accuracy is required in the process of creating the power conversion device described above, the through hole is crushed by the pressure when the green sheet is bonded. In order to prevent the occurrence of poor penetration, as shown in FIG. 9, the through hole of the green sheet after forming the through hole may be filled with a resin paste, and the green sheet filled with the through hole may be pasted together. This resin for filling holes can be completely degreased in a temperature raising process at the time of firing, and is, for example, the same resin as that used for green sheets, but does not contain magnetic particles.
In other words, after the drilling process, a hole filling process for filling the through holes before the laminating process is provided except that a process similar to that described above is adopted, resulting in a penetration failure due to crushing at the time of bonding. There is no.

(Example 1)
FIG. 4 is a view showing the manufacturing process of Example 1, and FIG. 7 is a cross-sectional view of the main part corresponding to the YY ′ cross section of FIG.
(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 resin raw material ratio with respect to ferrite was 30% by volume.
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. This sheet was dried at 60 ° C. as it was and punched out to produce a green sheet 7. (FIG. 7 (a)) External punching was performed using a mold with dimensions taking into account 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. As the slit-like grooves on the first main surface, ten grooves having a size of 0.20 × 2.0 mm were formed at intervals of 0.20 mm to form electrode recesses of 0.2 × 0.2 mm. Through hole formation is a mold consisting of two types of square punches and dies of 0.15 × 0.15 mm and 0.10 × 0.10 mm for green sheets other than both outer sides, that is, green sheets forming the inner layer It was performed using. 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.
Drilling and slitting of the green sheet could be easily performed, and through holes and slits could be formed at a high rate even in die processing. This process produced no through-holes, and the green sheet was flexible, so there were no cracks or chips, and the yield was high.

(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 through-holes are positioned so as to firmly overlap with reference to the two through-holes. And 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 is performed using an electric furnace from room temperature to 160 ° C. over about 1 hour, from 160 ° C. to 400 ° C. for 4 hours, from 400 ° C. to 500 ° C. for 6 hours, and from 500 ° C. to 900 ° C. over 4 hours. The temperature rose. 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. When the through-holes of the obtained magnetic substrate were observed, no crushing occurred when any of the 0.15 × 0.15 mm square and 0.10 × 0.10 mm square molds and punches were used. Due to the sintering, the through-holes shrunk to about 90% in length.

(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. 7 (e), 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.

  Next, as shown in FIG. 7F, a protective film 6 is formed by thermocompression bonding of a 30 μm-thick film made of polyimide resin on the first conductor and the second conductor to form a thin film as shown in FIG. A substrate on which a large number of magnetic components were formed was produced.

Next, the power supply IC chip 9 was connected to the electrode 5 of the thin magnetic component. That is, the stud bump 10 was formed on the electrode pad of the IC chip 9, and the IC chip 9 was ultrasonically bonded to the electrode 5 of the thin magnetic component. Next, the IC chip 9 and the thin magnetic component were reinforced with the underfill 11.
Finally, using a dicer, it was cut into individual chips consisting of IC and thin magnetic parts.

(Example 2)
FIG. 5 shows a manufacturing process of the magnetic component of the second embodiment. FIG. 9 is a sectional view of the manufacturing process. The difference from Example 1 is that a hole filling step is provided between the through hole forming step and the laminating step. In the description of the present embodiment, portions that are the same as those in the first embodiment are omitted, and portions different from those in the first embodiment are mainly described.
(Through hole forming process)
A green sheet was prepared in the same manner as in Example 1, and after firing the green sheet, three types of corners of 0.15 × 0.15 mm, 0.10 × 0.01 mm, and 0.08 × 0.08 mm were used. Drilling was performed using a die punch and a die to obtain three types of green sheets having through holes of different sizes.

(Cavity filling process)
Using a metal mask in which only the through hole portion of the green sheet in which the through hole was formed was opened, the hole filling resin paste was printed by a vacuum printing machine, and the through hole was filled with the resin paste. As the resin paste, polyvinyl butyral and toluene mixed and defoamed were used.
After filling the resin paste, it was dried at 60 ° C. to produce a green sheet in which the through hole was filled with the resin.

Firing was carried out in the same manner as in Example 1 except that a green sheet filled with resin in the through holes was used. When the through hole of the magnetic substrate having the through hole obtained by the firing process was observed, the through hole was not crushed or deformed, and a through hole having excellent dimensional accuracy was formed.
A chip composed of an IC and a thin magnetic component was fabricated in the same manner as in Example 1 except that this magnetic substrate was used.

(Comparative Example 1)
A thin magnetic component was manufactured by the manufacturing process shown in FIG. 6, which is a conventional method.
That is, a green sheet having a predetermined size was produced in the same manner as in Example 1 until the outer shape was punched. Six green sheets were subjected to temporary pressure bonding and lamination pressure bonding under the same conditions as in Example 1.
Next, this laminated green sheet was fired under the same conditions as in Example 1 to form a magnetic substrate, and then a through hole of 0.15 × 0.15 mm was formed by laser processing. The diameter on the processing introduction side and the diameter on the outlet side were different and tapered. In addition, there were problems such as cracks in some magnetic substrates.

  According to the present invention, even a thin magnetic component having a fine pattern can be manufactured with high accuracy and high yield.

The top view of one Embodiment of the thin magnetic component by the manufacturing method of this invention XX 'sectional drawing of one Embodiment of the thin magnetic component by the manufacturing method of this invention YY 'sectional view of one embodiment of a thin magnetic component manufactured by the manufacturing method of the present invention Production flow of thin magnetic component of Example 1 Production flow of thin magnetic component of Example 2 Process flow for manufacturing thin magnetic parts of conventional technology (Comparative Example 1) Sectional drawing which shows the thin magnetic component manufacture process of Example 1 Sectional drawing of thin magnetic component and IC chip by manufacturing method of this invention Sectional drawing which shows a part of thin magnetic component manufacturing process of Example 2.

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: Protective film 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

Claims (5)

  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. 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. A thin magnetic component characterized in that is formed.   Slit-like grooves on the front and back of the green sheet containing magnetic powder and resin, and a drilling / slit processing step that provides a through hole that connects the slit-like grooves on the front and back sides, and firing the green sheet after the drilling / slit processing step And a first conductor is provided in a slit-like groove formed on one surface (first main surface) of the magnetic substrate, and the other surface (second main surface) of the magnetic substrate is provided. A method of manufacturing a thin magnetic component, comprising a conductor forming step of providing a second conductor, providing a connection conductor in a through hole of the magnetic substrate, and forming a coil conductor with the first conductor, the second conductor, and the connection conductor .   It has a laminating step of laminating a plurality of green sheets after drilling / slit processing, and the firing step is firing the green sheet laminate after the drilling / slit processing step, and the slit-like grooves are laminated. 3. The method of manufacturing a thin magnetic component according to claim 2, wherein the method is provided only on the green sheet forming the front and back surfaces of the thin magnetic component.   Between the drilling / slit processing step and the laminating step, there is a resin filling step of filling the slit-like grooves and through holes formed in the drilling / slit processing step with a resin that disappears by firing. Item 4. A method for manufacturing a thin magnetic part according to Item 3.   5. The method of manufacturing a thin magnetic component according to claim 2, wherein the drilling / slit processing step is performed by sandblasting or laser processing.

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