JP2001267751A - Capacitor-incorporating substrate and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitor-incorporating substrate, which has high productivity and can have its circuit board made small-sized and contribute to an increase in the speed of a digital circuit, and to provide its manufacturing method. SOLUTION: After a dielectric film 2 of acrylic resin is formed by an electrophoresis on the roughened surface of copper foil 1, an aluminum layer 3 is formed at a specific position on the dielectric film 2 to complete a thin capacitor, which is thermocompression bonded by compression to an insulating substrate 4 provided with an interstitial via hole 5 filled with copper paste 6 in advance, so that the capacitor incorporated substrate can be manufactured which can shorten the wiring distance between the capacitor and a CPU and make circuit board small-sized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a substrate with a built-in capacitor used in electronic equipment and a method of manufacturing the same.
In particular, the present invention relates to a substrate with a built-in capacitor, which is provided in a high-speed operating electric circuit and has a built-in capacitor used for bypassing high-frequency noise and preventing fluctuation of a power supply voltage, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, miniaturization and high performance of electronic devices have been remarkable. Accordingly, electronic components such as capacitors have been strongly required to be smaller, thinner, and have excellent performance. Also, circuit boards on which a large number of electronic components are mounted have attempted to reduce the size of electronic devices by increasing the mounting density as much as possible.

However, in reality, the area occupied by mounted components such as capacitors on a circuit board is still large. This is expected to be a major obstacle in further miniaturizing electronic devices in the future. In order to solve such a problem, attempts to reduce the size and thickness of the circuit board by incorporating electronic components such as a capacitor in the circuit board have recently been active (for example, Japanese Patent Application Laid-Open No. H10-56251). Gazette, JP-A-11-68321).

On the other hand, in recent years, digital circuits have the following problems in terms of functions.

In a high-speed digital circuit such as a computer that needs to process a large amount of information at high speed, the clock frequency in the CPU chip is 100 MHz to several hundred MHz.
It is expected to enter the GHz band in the near future. Also, in order to suppress an increase in total power consumption due to an increase in the total number of elements of the LSI, the power supply voltage of the IC circuit tends to decrease.

As the frequency and voltage of IC circuits increase,
A major problem is that the power supply voltage fluctuates due to noise and malfunctions occur. The reason that such a problem occurs is that the permissible fluctuation width of the power supply voltage has become smaller as the power supply voltage decreases. To prevent malfunction due to high frequency noise, a capacitor is usually installed around the power supply. Capacitors used in such applications are called bypass capacitors or decoupling capacitors, and function to remove high-frequency noise and prevent momentary drops in power supply voltage by instantaneous energy supply from the capacitors. . The magnitude of the capacitance of the capacitor plays an important role in this energy supply.

Although an ideal capacitor should have only a capacitance component with no resistance component or inductance component, an actual capacitor has a series resistance component and a series inductance component. The impedance of the capacitance component decreases with increasing frequency, and the inductance component increases with increasing frequency. For this reason, as the operating frequency increases in the future, it is expected that the inductance component of the capacitor element itself and the inductance component due to wiring will cause noise. For this reason, it is necessary to use a capacitor having as small an inductance component as possible and to increase the self-resonant frequency of the capacitor itself so that the capacitor functions as a capacitor up to a high frequency range. In addition, the mounting position of the decoupling capacitor is preferably as close to the CPU as possible to minimize the inductance component due to the wiring.

[0008] On the other hand, the use rated voltage of the capacitor to be installed can be further reduced in the future as the power supply voltage becomes lower as described above.

In order to cope with the problem of increasing the frequency and the voltage of an IC circuit as described above, a high-performance capacitor is embedded in a circuit board to reduce the wiring distance between the CPU and the capacitor as much as possible. Are disclosed (for example, JP-A-4-211191 and JP-A-1-21191).
0-335178 and JP-A-11-111561).

In order to dramatically increase the miniaturization of electronic equipment and the speeding up of circuits in the future, it is essential to incorporate a high-performance capacitor in a circuit board.

Until now, inventions in which a capacitor having an inorganic high dielectric constant dielectric is incorporated in a ceramic substrate (for example, Japanese Patent Application Laid-Open Nos. H4-211191 and H11-6)
8321, JP-A-8-181453, JP-A-10-335178, JP-A-11-11156
No. 1) or an invention in which a capacitor is built in a resin substrate (for example, Japanese Patent Application Laid-Open Nos.
Some inventions have been disclosed, such as JP-A-242055 and JP-A-10-56251.

[0012]

At present, the mainstream of circuit board materials in small portable equipment represented by portable telephones is resin boards. There is a strong need for a technology for incorporating a capacitor having flexibility, excellent high-frequency characteristics, and various capacitances in a resin substrate.

[0013] Among the inventions disclosed so far, many ceramic-based materials that require high-temperature firing as a dielectric are embedded in a ceramic substrate (for example, Japanese Patent Application Laid-Open Nos. 8-222656 and 8-222). -181453
Reference). However, when a capacitor is built in a resin substrate, it is impossible to form a ceramic dielectric paste in the resin substrate and then fire the entire resin substrate at a high temperature. For this reason, it is necessary to embed a single ceramic capacitor in the resin substrate later. In addition, some high dielectric constant ceramic dielectrics have a large decrease in the dielectric constant in the GHz band, and many have poor temperature characteristics. there were.

In Japanese Patent Application Laid-Open No. H10-56251, a through hole is provided in a resin substrate, and a dielectric is filled therein.
An invention of a circuit board to which a function of a capacitor is added is disclosed. In this method, the dielectric must be filled to the entire thickness of the resin substrate, so that the dielectric is inevitably thicker, and only the area of the hole functions as a capacitor. Is expected to be difficult to obtain. In addition, a complicated operation is required to simultaneously produce capacitors having various capacitances by changing the area of the hole or changing the dielectric constant of the filler.

In most of the resin substrates used at present, a circuit pattern is formed by applying pressure and heat press bonding (thermocompression bonding) of copper foil to a resin substrate and then dissolving and removing (etching) unnecessary portions of the copper foil. Has formed. When a plurality of resin substrates to which copper foil is bonded are thermocompression-bonded to form a multilayer, the substrate layers are electrically connected to each other via a conductive material such as copper paste filled in via holes and through holes provided in the resin substrate. It is connected. When a capacitor is built in such a resin substrate, it is desirable to use a method that incorporates a capacitor that is easily adapted to the manufacturing process of the resin substrate and that does not increase the manufacturing cost.

If a single capacitor is to be individually incorporated in the resin substrate as described above, a step of providing a cutout space for embedding the capacitor in a circuit board material is required, which is expected to increase the cost.

Further, at the time of pressing at the time of manufacturing a resin substrate,
Since a large mechanical stress is applied, Japanese Patent Application Laid-Open No. 6-181
The use of an inorganic oxide thin film such as aluminum oxide or tantalum pentoxide as a dielectric material as described in Japanese Patent Publication No. 369 has a possibility that the dielectric is brittle and may be broken, which is suitable for a manufacturing process. Not.

Further, as described in JP-A-8-125302 and JP-A-8-242055, a method for forming a capacitor by applying a dielectric paste to a copper foil adhered to an insulating substrate is disclosed in JP-A-8-125302. It is presumed that it was difficult to control the thickness of the body, and it was difficult to increase the capacitance and obtain the capacitance accuracy.

An object of the present invention is to provide a substrate with a built-in capacitor which is suitable for a circuit board manufacturing process, is suitable for a high frequency application, and can contribute to further downsizing of an electronic device, and a method of manufacturing the same. With the goal.

[0020]

To achieve the above object, a substrate with a built-in capacitor according to claim 1 is formed by providing a dielectric film and a conductor layer between an insulating substrate and a part of a circuit pattern. A plurality of capacitors, and the dielectric films located at least on the same surface are made of the same material and have substantially the same thickness.

According to a second aspect of the present invention, there is provided a substrate with a built-in capacitor comprising a plurality of capacitors formed by providing a dielectric film and a conductor layer on a part of a circuit pattern provided on an insulating substrate, and being provided at least on the same surface. The dielectric films are made of the same material and have substantially the same thickness.

According to a third aspect of the present invention, there is provided a substrate with a built-in capacitor according to the first or second aspect, comprising a capacitor having at least one of a circuit pattern and a conductive layer which are in contact with the dielectric film and have different areas.

According to a fourth aspect of the present invention, there is provided the substrate with a built-in capacitor according to any one of the first to third aspects, wherein the dielectric film has at least one of a roughened circuit pattern and a conductive layer. .

According to a fifth aspect of the present invention, in the substrate with a built-in capacitor according to any one of the first to fourth aspects, when a dielectric film of a different material is provided, it is arranged on a different surface.

According to a sixth aspect of the present invention, in the capacitor-containing substrate according to any one of the first to fourth aspects, when dielectric films having different thicknesses are provided, they are arranged on different surfaces.

According to a seventh aspect of the present invention, there is provided the substrate with a built-in capacitor according to any one of the first to sixth aspects, wherein an interstitial via hole is provided in the insulating substrate, and the interstitial via hole is connected to a circuit pattern or a conductive layer to electrically connect the substrate. Connect.

According to an eighth aspect of the present invention, in the capacitor-containing substrate according to any one of the first to seventh aspects, the insulating substrate is a resin substrate, and the dielectric film is formed of an organic polymer.

According to a ninth aspect of the present invention, there is provided the substrate with a built-in capacitor according to any one of the first to seventh aspects, wherein the insulating substrate is a resin substrate, and the dielectric film is a composite film composed of inorganic fine particles and an organic polymer.

[0029] The substrate with a built-in capacitor according to claim 10 is
In the eighth or ninth aspect, the organic polymer is any one of an acrylic resin, an epoxy resin, a fluorocarbon resin, a polyester resin, and a polyimide.

The substrate with a built-in capacitor according to claim 11 is
In a ninth aspect, the inorganic fine particles are a perovskite-type ferroelectric compound or a metal oxide.

According to a twelfth aspect of the present invention, there is provided a substrate with a built-in capacitor.
In any one of claims 8 to 11, the conductive layer is made of a conductive polymer.

The substrate with a built-in capacitor according to claim 13 is
The thickness of the dielectric film forming the capacitor is 1 μm or less.

According to a fourteenth aspect of the present invention, there is provided a method of manufacturing a substrate with a built-in capacitor, wherein the dielectric film of the substrate with a built-in capacitor is formed by using an electrophoretic electrodeposition method. .

According to a fifteenth aspect of the present invention, in the method of manufacturing a substrate with a built-in capacitor, a first step of forming a dielectric film on one surface of a metal foil by an electrophoretic electrodeposition method, and a desired position on the surface of the dielectric film A second step of forming a conductor layer on the metal foil to complete a capacitor, a third step of bonding the conductor layer side of the metal foil having the capacitor to an insulating substrate, and dissolving an unnecessary portion of the metal foil. And a fourth step of removing.

A method of manufacturing a substrate with a built-in capacitor according to claim 16 includes a first step of bonding a metal foil to an insulating substrate;
A second step of dissolving and removing unnecessary portions of the metal foil to form a circuit pattern, a third step of forming a dielectric film at a desired position of the circuit pattern by electrophoretic electrodeposition, And forming a conductor layer on the surface of the dielectric film to complete the capacitor.

According to a seventeenth aspect of the present invention, in the manufacturing method of the fifteenth or sixteenth aspect, a resist is used to form a conductive layer or a dielectric film at a desired position.

According to a eighteenth aspect of the present invention, there is provided a method of manufacturing a substrate with a built-in capacitor according to any one of the fifteenth to seventeenth aspects, wherein the roughened metal foil is used and an electrophoretic electrodeposition method is used to follow the rough surface shape. It forms a body film.

[0038]

A substrate with a built-in capacitor according to a first aspect of the present invention includes a plurality of capacitors formed by providing a dielectric film and a conductive layer between an insulating substrate and a part of a circuit pattern. Since the dielectric films located are made of the same material and have substantially the same thickness, it is possible to simultaneously form the dielectric films constituting a plurality of capacitors located on the same surface.

According to a second aspect of the present invention, there is provided a substrate with a built-in capacitor comprising a plurality of capacitors formed by providing a dielectric film and a conductive layer on a part of a circuit pattern provided on an insulating substrate, and being provided at least on the same surface. Since the dielectric films are made of the same material and have substantially the same thickness, it is possible to simultaneously form the dielectrics constituting a plurality of capacitors located on the same surface.

According to a third aspect of the present invention, there is provided a substrate with a built-in capacitor according to the first or second aspect, wherein a capacitor having a different area in at least one of a circuit pattern and a conductive layer in contact with the dielectric film is provided. With regard to the above capacitor, capacitors having various capacitances can be built in the circuit board.

According to a fourth aspect of the present invention, there is provided a substrate with a built-in capacitor, wherein the dielectric film has a shape following at least one of a roughened circuit pattern or a conductive layer. The contact area between the dielectric film and the circuit pattern or the conductor layer is increased, and the capacitance of the formed capacitor can be easily increased.

According to a fifth aspect of the present invention, in the capacitor-containing substrate according to any one of the first to fourth aspects, when a dielectric film made of a different material is provided, the substrate is disposed on a different surface. Can provide various electrostatic capacities only by changing the material of the dielectric film to be constituted.

According to the sixth aspect of the present invention, the substrate with a built-in capacitor is arranged on a different surface when a dielectric film having a different thickness is provided in any one of the first to fourth aspects. For multiple capacitors,
Various capacitances can be obtained simply by changing the thickness of the constituent dielectric film.

According to a seventh aspect of the present invention, there is provided the substrate with a built-in capacitor according to any one of the first to sixth aspects, wherein an interstitial via hole is provided in the insulating substrate, and the interstitial via hole is connected to a circuit pattern or a conductor layer to electrically connect the substrate. Because of the connection, the wiring distance between the CPU and the capacitor is shortened to reduce the inductance due to the wiring,
It is possible to prevent noise from occurring due to wiring.

According to an eighth aspect of the present invention, in the capacitor-containing substrate according to any one of the first to seventh aspects, the insulating substrate is a resin substrate, and the dielectric film is formed of an organic polymer. Has a small difference in the coefficient of thermal expansion, thereby improving compatibility in the manufacturing process, and having flexibility and increasing resistance to mechanical stress against deformation of the circuit board and pressure during the manufacturing process. . in addition,
It is possible to incorporate a capacitor having excellent high frequency characteristics, temperature characteristics, and bias voltage characteristics.

According to a ninth aspect of the present invention, in the capacitor-containing substrate according to any one of the first to seventh aspects, the insulating substrate is a resin substrate, and the dielectric film is a composite film composed of inorganic fine particles and an organic polymer. Because it has both high dielectric constant of fine particles and mechanical stress resistance of organic polymer, it incorporates a capacitor with a higher capacity than the polymer dielectric film alone, and has mechanical resistance against deformation of the circuit board and pressure during the manufacturing process. It is possible to increase the target stress.

The substrate with a built-in capacitor according to claim 10 is
Since the organic polymer is any one of an acrylic resin, an epoxy resin, a fluorocarbon resin, a polyester resin, and a polyimide according to claim 8, a circuit board having a built-in capacitor having excellent characteristics is provided. can get.

[0048] The substrate with a built-in capacitor according to claim 11 is
In the ninth aspect, since the inorganic fine particles are perovskite-type ferroelectric compounds or metal oxides, the dielectric constant of the dielectric film can be increased, so that a large-capacity capacitor can be built in the circuit board. .

According to a twelfth aspect of the present invention, there is provided a substrate with a built-in capacitor.
In any one of claims 8 to 11, since the conductive layer is a conductive polymer, it is possible to increase the coverage of the dielectric film, so that the capacity of the built-in capacitor can be increased.

The substrate with a built-in capacitor according to claim 13 is
Since the thickness of the dielectric film forming the capacitor is 1 μm or less, a capacitor having a high capacitance density can be built in, so that a smaller circuit board can be obtained.

According to a fourteenth aspect of the present invention, there is provided a method of manufacturing a substrate with a built-in capacitor, wherein the dielectric film of the substrate with a built-in capacitor is formed by using an electrophoretic electrodeposition method. Since the film thickness can be adjusted by electrical control, capacitors having various capacitances can be built in the substrate. In addition, a substrate with a built-in capacitor can be provided in which the dielectric film is not easily peeled off since the adhesive strength with the circuit pattern or the conductor layer is strong.

According to a fifteenth aspect of the present invention, there is provided a method of manufacturing a substrate with a built-in capacitor, comprising: a first step of forming a dielectric film on one surface of a metal foil by an electrophoretic electrodeposition method; and a desired position on the surface of the dielectric film. A second step of forming a conductor layer on the metal foil to complete a capacitor, a third step of bonding the conductor layer side of the metal foil having the capacitor to an insulating substrate, and dissolving an unnecessary portion of the metal foil. Since it has the fourth step of removing, it has become possible to form a high-performance dielectric film on a metal foil such as a copper foil conventionally used for a circuit board. It can be built into a circuit board.

A method of manufacturing a substrate with a built-in capacitor according to a sixteenth aspect includes a first step of bonding a metal foil to an insulating substrate;
A second step of dissolving and removing unnecessary portions of the metal foil to form a circuit pattern, a third step of forming a dielectric film at a desired position of the circuit pattern by electrophoretic electrodeposition, And the fourth step of forming a conductor layer on the surface of the dielectric film to complete the capacitor, thereby making it possible to form a high-performance dielectric film at a predetermined position on the circuit pattern. In addition, it is possible to manufacture a circuit board including a high-performance capacitor at a predetermined position on a circuit pattern.

In the method for manufacturing a substrate with a built-in capacitor according to the seventeenth aspect, a resist is used to form a conductor layer or a dielectric film at a desired position in the fifteenth or sixteenth aspect, so It is possible to form a capacitor at an arbitrary position, so that the capacitor can be easily divided in the circuit board.

The method for manufacturing a substrate with a built-in capacitor according to claim 18 is the method according to any one of claims 15 to 17, wherein the roughened metal foil is used and the dielectric material follows the rough surface shape by electrophoretic electrodeposition. Since the body film is formed, the contact area between the dielectric film and the metal foil is increased, and the capacitance of the formed capacitor can be easily increased. Can be built-in.

(Embodiment 1) Hereinafter, Embodiment 1 will be described with reference to FIGS. FIG. 1 is a schematic diagram of a cross section of a substrate with a built-in capacitor described in the first embodiment, FIG. 2 is a diagram showing a dielectric film formed on a roughened copper foil, and FIG. It is a figure showing the manufacturing method of an embedded substrate. First, the structure of a target substrate with a built-in capacitor will be described with reference to FIGS.

Reference numeral 1 denotes a copper foil having a roughened surface and a thickness of 18 μm (surface roughness Rz = 8 μm). The copper foil 1 is subjected to thermocompression bonding on an insulating substrate 4 (thickness of 100 μm) and then to a circuit by etching. It has been patterned. However, before etching, a dielectric film 2 of an acrylic resin formed by an electrophoretic electrodeposition method was formed on one entire surface of the copper foil 1. In the first embodiment, the surface on which the dielectric film 2 is formed is a surface to be adhered to the insulating substrate 4 during thermocompression bonding. The dielectric film 2 made of an acrylic resin is
As shown in FIG. 2, the copper foil 1 is formed so as to follow the surface shape of the roughened copper foil 1. The aluminum layer 3 is made of the dielectric film 2
Formed on the surface of the substrate by vacuum evaporation. The structure formed by the copper foil 1, the dielectric film 2, and the aluminum layer 3 is the thin capacitor of the first embodiment. The total thickness of this thin capacitor was 19 μm or less.

This thin capacitor is bonded by thermocompression to an insulating substrate 4 of a prepreg formed by impregnating an aramid nonwoven fabric with an epoxy resin. The interstitial via hole 5 is formed in the insulating substrate 4 by CO ₂ laser processing, and the inside is filled with a copper paste 6.

As shown in FIG. 1, an insulating substrate 4 having a thin capacitor and an interstitial via hole 5 arranged at arbitrary positions is sequentially thermocompression-bonded and joined.
The multilayer built-in capacitor substrate of the first embodiment is obtained.

Next, a method for manufacturing the substrate with a built-in capacitor according to the first embodiment will be described in detail with reference to FIG.

First, in step 1, the copper foil 1 having a roughened surface is immersed in a solution in which fine particles of acrylic resin are dispersed in a stainless steel container, and the copper foil 1 is placed between the copper foil 1 and the stainless steel container. A voltage of 15 V was applied for 1 minute so that By doing so, the acrylic resin fine particles are negatively charged in the solution, electrophoresed in the direction of the copper foil 1, and the dielectric film 2 of the acrylic resin is formed on the copper foil 1.

In the first embodiment, a resist is applied to one surface of the copper foil 1 before electrodeposition so that the dielectric film 2 of an acrylic resin is formed only on one surface.

After the electrophoretic electrodeposition, the dielectric film 2 was completed by thermosetting at 180 ° C. for 30 minutes. Thereafter, the resist was removed with a solvent.

When the surface of the electrodeposited acrylic resin dielectric film 2 is observed with a scanning electron microscope (SEM),
It was found that the dielectric film 2 was formed along the complicated surface shape of the roughened copper foil 1. FIG. 3 schematically shows an enlarged cross section of a state where the dielectric film 2 is formed on the roughened copper foil 1. By using the electrophoretic electrodeposition method, it is possible to form the dielectric film 2 with a uniform thickness even with a conductor having a complicated surface shape such as a roughened copper foil 1. It also has strong adhesive strength. Further, by controlling the quantity of electricity during electrodeposition, it is possible to make the film thinner than the thinnest polymer film on the market. In addition, since the electrodeposition method is based on the principle that an insulating film is formed where electricity flows, pinhole generation can be prevented more than with a coating film. The thickness of the dielectric film 2 formed in the first embodiment was 0.3 μm, and the breakdown voltage was 20V.

The material of the dielectric film 2 electrodeposited here is not limited to the first embodiment. In addition to the acrylic resin, an epoxy resin, a fluorocarbon resin, a polyester resin, a polyimide resin, or the like. Any polymer that can be electrophoretically deposited can be used for the dielectric film 2 according to the first embodiment. Preferably, a polymer material having excellent dielectric properties in the GHz band, high heat resistance, excellent adhesion to the copper foil 1, and low hygroscopicity is preferred.

In the first embodiment, a resin that is negatively charged in a solution is used as the dielectric film 2, but a resin that is positively charged may be formed on the cathode side. In general, a carboxylic acid group is usually introduced into the electrodeposition resin when charged negatively, and an amino group is generally introduced when charged positively.

In the first embodiment, a thermosetting acrylic resin is used for the dielectric film 2. However, it was experimentally confirmed that a capacitor having excellent characteristics can be obtained even if an ultraviolet curable polymer is used. Confirmed.

As described above, the method of the first embodiment is
Various materials for the organic polymer-based dielectric film 2 to be used can be selected according to the desired characteristics.

The organic polymer-based dielectric has a dielectric constant of 2 to 5 which is smaller than that of the inorganic dielectric, but has an advantage of excellent high-frequency characteristics. Therefore, in the first embodiment, the capacitance of the capacitor is increased by effectively utilizing the large surface area of the copper foil 1 while maintaining the excellent high-frequency characteristics of the organic polymer. I aimed to do it.

Next, in step 2, an aluminum layer 3 was formed at a predetermined position by vacuum evaporation to complete a thin capacitor. The deposition area was 3 mm × 3 mm. At the time of vapor deposition, vapor deposition was performed using a mask so that the aluminum layer 3 was formed only at predetermined positions.

In the first embodiment, the electrophoretic electrodeposition method is employed when forming the acrylic resin dielectric film 2. Therefore, the capacitance is adjusted by adjusting the electrodeposition conditions and the surface area of the copper foil 1. It can be done by changing. For example, if it is desired to reduce the capacitance, the film thickness may be increased by increasing the applied voltage at the time of electrodeposition, or if the capacitance is desired to be increased, the applied voltage at the time of electrodeposition may be reduced, Copper foil 1
Should be increased.

Further, a dielectric film 2 of an acrylic resin and an aluminum layer 3 may be formed on both surfaces of the copper foil 1 so as to obtain a capacitance twice as large as that of a capacitor on one surface.

In the first embodiment, the deposited aluminum layer 3 is used as the conductor layer. However, for example, zinc, copper, chromium, a zinc / aluminum alloy, a zinc / copper alloy, etc. may be deposited. .

It is also preferable to form a metal such as copper by electroless plating in addition to the vapor-deposited metal. Further, a conductive polymer such as polypyrrole used as a cathode material of a solid electrolytic capacitor may be formed.

Next, in step 3, an interstitial via hole 5 of 150 μm was formed on an insulating substrate 4 which was a prepreg formed by impregnating an aramid fiber with an epoxy resin, using a CO ₂ laser processing machine.

In the first embodiment, the insulating substrate 4 that is a prepreg is made of aramid fiber impregnated with an epoxy resin, but glass fiber or paper impregnated with an epoxy resin is also suitable. Further, the type of prepreg resin used is not limited to the epoxy resin.

Then, in step 4, copper paste 6 was filled in interstitial via hole 5.

In the first embodiment, the copper paste 6 is used as a conductive material in the interstitial via hole 5, but the present invention is not limited to this material. A conductive adhesive such as a silver paste or a nickel paste, or a metal formed by plating is also suitable.

Next, in step 5, the copper foil 1 on which the thin capacitor was formed was bonded to the prepreg insulating substrate 4 to which the copper foil 1 had been bonded on one side in advance by heating and pressing. The conditions for bonding are as follows: a pressure of 50 kgf / cm ² , a temperature of 200 ° C., and a holding time of 60 under a vacuum atmosphere.
Minutes. At the time of bonding, positioning was performed so that conduction between the thin capacitor and the copper paste 6 in the interstitial via hole 5 was sufficiently ensured, and pressing was performed.

Next, in Step 6, an unnecessary portion of the copper foil 1 having the thin capacitor was dissolved and removed (etched) with a ferric chloride solution to form a circuit pattern made of the copper foil 1 on the insulating substrate 4.

Next, in step 7, the capacitor built-in substrate having another circuit pattern formed in steps 1 to 6 was thermocompression-bonded to produce a two-layer laminated capacitor built-in substrate.

By repeating the above steps, a multilayer capacitor-containing substrate having a circuit pattern in which the capacitor and the resin substrate are integrated can be manufactured.

If the electrophoretic electrodeposition method is employed when forming the dielectric film 2 as in the first embodiment, it is possible to reduce the thickness to 1 μm or less, which cannot be realized with a conventional commercially available polymer film. The dielectric film 2 having a uniform thickness can be formed on the roughened copper foil 1 having a complicated surface shape. Also, the size and thickness of the circuit board can be reduced and the inductance component due to the wiring between the capacitor and the CPU can be reduced more reliably than when the capacitor is mounted on the surface. Further, the labor and cost for mounting a large number of capacitor components can be reduced.

Since the voltage of the digital circuit tends to decrease, and the voltage of 2 V or less tends to increase in the future, the dielectric film 2 thinner than that of the first embodiment can be used. Therefore, if the electrodeposition voltage is reduced to make the electrode thinner, the capacity density can be further increased.

Further, the leakage current shows a small value of 1 nA or less even though the heating / pressing step has been performed. From this, the capacitor of the first embodiment is
Since the flexible organic polymer dielectric film 2 was formed by the electrophoretic electrodeposition method, it can be said that mechanical stress resistance is strong.

Since the copper foil 1 serving as the lower electrode of the dielectric film 2 was originally used for a circuit board, the copper foil 1 with a thin capacitor was used when manufacturing the circuit board.
Is introduced into the steps so far, a substrate with a built-in capacitor can be manufactured without greatly changing the conventional method for manufacturing a circuit board as in the first embodiment.

(Embodiment 2) Embodiment 2 will be described below with reference to the drawings.

FIG. 4 is a schematic cross-sectional view of a substrate (single layer) with a built-in capacitor described in the second embodiment. Since the dielectric film 8 of the epoxy resin and the copper layer 9 formed by vacuum evaporation were formed in advance by using a photoresist,
As shown in FIG. 4, each capacitor is incorporated in the insulating substrate 4 in a divided state.

Next, a method of manufacturing the capacitor built-in substrate according to the second embodiment will be described in detail with reference to FIG.

First, in step 1, a positive photosensitive resist is applied to the copper foil 1 whose surface is roughened by spin coating, and after exposure and development, a dielectric film 8 is formed as shown in FIG. The resist 7 for the mask at the time was obtained. The area of the formation portion of the dielectric film 8 is 3 mm × 3 mm as in the first embodiment.
And

Next, in step 2, the copper foil 1 on which the resist 7 is formed is immersed in a solution in which the epoxy resin fine particles are dispersed in a stainless steel container, and the copper foil 1 is placed between the copper foil 1 and the stainless steel container. A voltage of 8 V was applied for one minute so as to serve as a cathode. By doing so, the epoxy resin fine particles are positively charged in the solution, electrophoreses in the direction of the copper foil 1 which is the cathode, and the epoxy resin fine particles are applied only to the portion of the copper foil 1 where the resist 7 is not formed. A resin dielectric film 8 was formed.
After the electrophoretic electrodeposition, the resultant was thermally cured at 180 ° C. for 30 minutes to complete the dielectric film 8 of an epoxy resin.

When the surface of the electrodeposited epoxy resin dielectric film 8 was observed with a scanning electron microscope (SEM),
It was found that the dielectric film 8 of an epoxy resin was formed following the complicated surface shape of the roughened copper foil 1.

Next, in step 3, a copper layer 9 was formed by vacuum evaporation.

Next, in step 4, the resist 7 was removed using a solvent. By doing so, a thin capacitor divided on the copper foil 1 was completed.

Next, in step 5, the copper foil 1 on which the thin capacitor was formed was bonded to the insulating substrate 4 of the prepreg by heating and pressing. As in steps 3 and 4 of the first embodiment, 150 μm interstitial via hole 5 filled with copper paste 6 was previously provided on insulating substrate 4. The conditions for bonding are as follows: a pressure of 50 kgf / cm ² , a temperature of 200 ° C. and a holding time of 6 in a vacuum atmosphere.
0 minutes. At the time of bonding, positioning was performed so that conduction between the thin capacitor and the copper paste 6 in the interstitial via hole 5 was sufficiently ensured, and pressing was performed.

Next, in Step 6, an unnecessary portion of the copper foil 1 having the thin capacitor was dissolved and removed (etched) with a ferric chloride solution to form a circuit pattern made of the copper foil 1 on the insulating substrate 4. In this way, a substrate with a built-in capacitor in which thin capacitors divided on a circuit pattern are arranged can be manufactured. Further, by repeating the processes of Steps 1 to 6, a multilayer capacitor-containing substrate can be obtained.

In the second embodiment, since a resist is used, it is possible to divide and incorporate a capacitor in a circuit board.

(Embodiment 3) In Embodiment 3, instead of the vacuum-deposited copper layer 9 of FIG. 4 in Embodiment 2,
A substrate with a built-in capacitor having the same configuration as that of the second embodiment was manufactured except that a conductive polymer, polyethylene dioxythiophene, a carbon paste, and a copper paste were sequentially formed on the dielectric film 8.

The method for forming the conductive polymer polyethylene dioxythiophene is described below.

A mixture of a 0.3 mol / l ferric naphthalene sulfonate ethanol solution and a 1 mol / l ethylene dioxythiophene monomer (manufactured by Bayer) in an ethanol solution was applied to the portion where the dielectric film was formed. It was applied several times. And it kept at 110 degreeC for 60 minutes, and promoted chemical polymerization. Then, it was washed with ethanol and water. By doing so, polyethylene dioxythiophene can be formed on the dielectric film. Then, a current collector of a carbon paste and a copper paste was formed on the surface, and then the resist was removed with a solvent to complete a thin capacitor.

In the third embodiment, polyethylene dioxythiophene is formed as the conductive polymer. However, it is needless to say that the material is not limited to the above-mentioned materials, but may be polypyrrole, polythiophene, polyaniline, or derivatives thereof.

(Embodiment 4) Embodiment 4 will be described below with reference to the drawings.

FIG. 6 is a schematic cross-sectional view of the substrate with a built-in capacitor described in the fourth embodiment. This figure shows a multilayer substrate obtained by pressing and heating and pressing a total of four layers of the substrate with a built-in capacitor manufactured in the second embodiment.

According to the fourth embodiment, a capacitor can be built in each layer of the multilayer substrate. Further, by changing the conditions for forming the thin capacitor in each layer as in the first to third embodiments, a large number of capacitors having different capacitances can be built in one multilayer substrate.

At present, the capacitance of the capacitors mounted around the CPU is in a wide range from the order of pF to the order of μF. In this embodiment, the electrodeposition conditions and the copper foil 1
By changing the surface area, a capacitor having a wide range of capacitance can be built in the multilayer substrate.

By employing the technique of the present embodiment, it is possible to greatly reduce the size of the entire circuit board as compared with a case where capacitors of various capacitances are surface-mounted,
The inductance component due to the wiring between U can be reliably reduced.

(Embodiment 5) The structure of a substrate with a built-in capacitor according to Embodiment 5 is the same as that shown in FIG.
It is the same as that shown in the second embodiment except that the dielectric film 8 made of epoxy resin is changed to a composite dielectric film made of barium titanate fine particles and acrylic resin.

A method for forming a composite dielectric film composed of inorganic fine particles and an organic polymer by electrophoretic electrodeposition in Embodiment 5 will be described below.

Barium titanate fine particles having a particle size of 0.1 μm were mixed with the acrylic resin electrodeposition solution used in the first embodiment. Barium titanate fine particles were mixed at a mass ratio of 0.1% with respect to the total mass of the electrodeposition solution, and triethylamine was added to adjust the pH to 8.2 so as to be negatively charged.

As in the first embodiment, when the copper foil 1 is immersed in the electrodeposition solution and a voltage of 15 V is applied, the charged barium titanate and the acrylic resin are electrophoresed simultaneously,
An organic / inorganic composite dielectric film made of an acrylic resin and barium titanate was formed on the copper foil 1.

The inorganic fine particles are not limited to barium titanate, but the effect can be exerted if the inorganic fine particles have a higher dielectric constant than a resin material. For example, perovskite compounds such as lead titanate and strontium titanate,
Metal oxides such as aluminum oxide, tantalum oxide, and titanium oxide are preferred.

In the fifth embodiment, the leakage current did not increase even if pressure was applied when bonding to the insulating substrate. Furthermore, the performance of the capacitor did not deteriorate even if the entire substrate was bent lightly.

When the surface of the dielectric film was observed with a scanning electron microscope (SEM), it was found that the acrylic resin plays a role of a barium titanate binder.

As described above, despite the fact that the capacitor of the fifth embodiment has an inorganic dielectric, it is strong against mechanical stress because the organic polymer which is flexible in the dielectric film is used. Probably because it played a role of a binder.

(Embodiment 6) A method of manufacturing a substrate with a built-in capacitor according to Embodiment 6 will be described in detail with reference to FIG.

First, in step 1, the roughened copper foil 1 was bonded to the insulating substrate 4 of the prepreg in which the aramid fiber was impregnated with the epoxy resin by heating and pressing. The prepreg used was one in which an interstitial via hole 5 previously filled with a copper paste 6 was formed.

Next, in Step 2, unnecessary portions of the copper foil 1 were etched with a ferric chloride solution to provide a circuit pattern and a lower copper electrode 10 for a capacitor.

Next, in step 3, the polyimide dielectric film 11 is electrically connected to the copper foil 13 via the interstitial via hole 5 by the electrophoretic electrodeposition method using the copper foil 13 as an electrode for electrodeposition. Formed only on the lower copper electrode 10 for a capacitor. When forming the dielectric film, the resist film 7 is masked on the circuit pattern as shown in FIG. 7 so that the dielectric film is electrodeposited where it is not desired to form the dielectric film. Was blocked. Also, the copper foil 13 as an electrodeposition electrode was masked (not shown) in advance and electrodeposited.

The details of the electrodeposition conditions for the dielectric film 11 made of polyimide are shown below. Dissolve 0.013 moles of 3,3 ', 4,4'-diphenylsulfonic acid tetracarboxylic dianhydride and 4,4'-methylenedianiline in 100 ml of N-methylpyrrolidone, and add 5 The reaction was carried out for an hour to obtain a polyamic acid solution. 1 part by weight of this polyamic acid solution, 3 parts by weight of dimethylformamide,
A mixture of 6 parts by weight of methanol and 0.01 part by weight of triethylamine was used as the electrodeposition solution of the sixth embodiment. The electrodeposited solution is put in a stainless steel container, and the patterned insulating substrate 4 is immersed in the electrodeposited solution.
A voltage of V was applied for one minute. In this way, a 3 μm thick polyimide dielectric film 11 was formed on the lower copper electrode 10 for capacitors on the insulating substrate 4.

The dielectric film 11 of polyimide is formed up to the edge of the lower copper electrode 10 for a capacitor as shown in FIG. 7 by using the electrophoretic electrodeposition method.

Next, in step 4, the upper copper electrode 12 was provided by electroless plating to complete a thin capacitor. Thereafter, the resist was removed with a solvent to complete a single-layer capacitor-containing substrate.

Next, in step 5, the insulating substrate 4 was further bonded to the single-layer capacitor built-in substrate formed in step 4.

By repeating steps 1 to 5 as described above, a multilayer capacitor-containing substrate can be manufactured.

According to the sixth embodiment, since the dielectric film 11 is formed after the copper foil 1 adhered to the insulating substrate 4 is patterned, the design of the place where the capacitor is installed becomes easy. Further, since the dielectric film 11 is electrodeposited on the copper foil 1 on the insulating substrate 4 in which the conduction with the interstitial via hole 5 is secured in advance, the work of aligning with the interstitial via hole 5 can be omitted. Further, since the dielectric film is formed by electrodeposition up to the edge of the copper foil, short-circuit failure when the counter electrode is provided can be eliminated.

Further, in the sixth embodiment, by repeating the process shown in FIG. 7, a multilayered substrate with a built-in capacitor can be formed. In the etching process of Step 2, the area of the lower copper electrode 10 for the capacitor is changed,
By changing the electrodeposition conditions in step 3, a multi-layer substrate incorporating capacitors having various capacitances can be obtained.

Although the first to sixth embodiments have mainly described a multilayer capacitor-containing substrate, it is needless to say that a single-layer capacitor-containing substrate may be manufactured without performing the multi-layering process. .

As described above, Embodiments 1 to 6
The electrical characteristics of the capacitors built in the circuit board obtained in (excluding the fourth embodiment) are summarized in (Table 1), and the results are described below. Table 1 shows the average value of ten built-in capacitors.

[0128]

[Table 1]

According to the first embodiment, the organic polymer dielectric film 2 is formed on the roughened copper foil 1 by electrophoretic electrodeposition.
Can be formed with a thickness of 1 μm or less, so that a normal organic polymer film having a thickness of 2 μm or more is
Thus, a capacitor having a higher capacitance density could be formed inside the circuit board.

According to the second embodiment, the dielectric film 8 can be made thinner and the capacitance can be increased by lowering the electrodeposition voltage than in the first embodiment.

According to the third embodiment, although the dielectric film is formed under the same conditions, the capacity is larger than that of the second embodiment. This is because the coverage of the dielectric film of the conductive polymer serving as the counter electrode was larger than that in the case of using the deposited metal.

It can be seen that the capacitor of the fifth embodiment has a larger capacitance than the capacitor of the first embodiment.
The reason why such a large capacity was obtained is that barium titanate contributed greatly to the high dielectric constant.

In the capacitor according to the sixth embodiment, the dielectric film made of polyimide is thicker than in the first to fifth embodiments by the electrophoretic electrodeposition method, so that the capacitance is reduced.
As described above, by increasing the voltage at the time of electrodeposition, a capacitor of the order of pF can be formed in the circuit board.

[0134]

According to the capacitor built-in substrate according to the first and second aspects, the dielectric films forming the plurality of capacitors provided on the same surface are made of the same material and have substantially the same thickness, so that the same thickness can be obtained. Since it is possible to form each dielectric that constitutes multiple capacitors located on the surface at once, it is possible to incorporate multiple capacitors into the circuit board without significantly changing the conventional circuit board manufacturing process. it can.

According to the capacitor built-in substrate according to the third aspect, by providing the capacitor having at least one of different areas of the circuit pattern or the conductor layer in contact with the dielectric film, the plurality of capacitors located on the same surface can be formed by a conventional method. Without significantly changing the circuit board manufacturing process
A plurality of capacitors having various capacitances can be built in the circuit board.

According to the capacitor built-in substrate according to the fourth aspect, by forming the dielectric film into a shape following at least one of the roughened circuit pattern and the conductor layer,
Since it is possible to increase the contact area between the dielectric film and the circuit pattern or the conductor layer and easily increase the capacitance of the formed capacitor, without significantly changing the conventional circuit board manufacturing process, A capacitor having a high capacitance density can be built in the circuit board.

In the capacitor built-in substrate according to the fifth aspect, when a dielectric film of a different material is provided, it is arranged on a different surface. Since various capacitances can be obtained simply by changing them, capacitors having various capacitances can be built in the circuit board without greatly changing the conventional circuit board manufacturing process.

In the capacitor built-in substrate according to the sixth aspect, when the dielectric films having different thicknesses are provided, they are arranged on different planes. Various capacitances can be obtained simply by changing the film thickness, so capacitors with various capacitances are built into the circuit board without drastically changing the conventional circuit board manufacturing process. can do.

According to the seventh aspect of the present invention, since the interstitial via hole is provided in the insulating substrate and the interstitial via hole is connected to a circuit pattern or a conductive layer to be electrically connected, the connection between the CPU and the capacitor is provided. Since the wiring distance can be reduced to reduce the inductance due to the wiring and prevent the generation of noise due to the wiring, it is possible to provide a substrate with a built-in capacitor suitable for high-frequency circuit applications.

In the substrate with a built-in capacitor according to the present invention, since a resin substrate is used as the insulating substrate and an organic polymer is used for the dielectric film, the difference in thermal expansion coefficient between the insulating substrate and the dielectric film is small. In addition to improving compatibility in the manufacturing process, it is possible to enhance the flexibility and the mechanical stress resistance against the deformation of the circuit board and the pressure during the manufacturing process. Capacitors can be built into circuit boards without significant changes. In addition, it is possible to incorporate a capacitor having excellent high-frequency characteristics, temperature characteristics, and bias voltage characteristics.

In the capacitor built-in substrate according to the ninth aspect, the insulating substrate is a resin substrate, and the dielectric film is a composite film composed of inorganic fine particles and an organic polymer. Because it has the mechanical stress resistance of, without significantly changing the conventional circuit board manufacturing process, it incorporates a capacitor with a higher capacity than the polymer dielectric film alone, and also deforms the circuit board and It is possible to increase the mechanical stress resistance against pressure and the like.

The substrate with a built-in capacitor according to claim 10 is
By using any of acrylic resin, epoxy resin, fluorocarbon resin, polyester resin, or polyimide as the organic polymer that constitutes the dielectric film, without significantly changing the conventional circuit board manufacturing process, Capacitors that take advantage of the excellent characteristics of each organic polymer can be built in.

The substrate with a built-in capacitor according to claim 11 is
By making the inorganic fine particles mixed into the dielectric film a perovskite-type ferroelectric compound or metal oxide,
Since the dielectric constant of the dielectric film can be increased, a large-capacity capacitor can be built in the circuit board without significantly changing the conventional circuit board manufacturing process.

The substrate with a built-in capacitor according to claim 12 is
By using an organic polymer as the main component of the dielectric film and a conductive polymer as the conductive layer, it becomes possible to increase the coverage of the dielectric film, thus significantly changing the conventional circuit board manufacturing process. Without this, the capacity of the built-in capacitor can be increased.

The substrate with a built-in capacitor according to claim 13 is
Since the thickness of the dielectric film forming the capacitor is 1 μm or less, it is possible to incorporate a capacitor having a high capacitance density, so that a smaller circuit board can be obtained.

According to a fourteenth aspect of the present invention, a method for manufacturing a substrate with a built-in capacitor uses the electrophoretic electrodeposition method for forming the dielectric film of the substrate with a built-in capacitor. Since the film thickness can be adjusted by electrical control, capacitors having various capacitances can be built in the substrate without significantly changing the conventional circuit board manufacturing process. In addition, a substrate with a built-in capacitor can be provided in which the dielectric film is not easily peeled off since the adhesive strength with the circuit pattern or the conductor layer is strong.

According to a fifteenth aspect of the present invention, there is provided a method of manufacturing a substrate with a built-in capacitor, comprising: a first step of forming a dielectric film on one side of a metal foil by electrophoretic electrodeposition; and a desired position on the surface of the dielectric film. A second step of forming a conductor layer on the metal foil to complete a capacitor, a third step of bonding the conductor layer side of the metal foil having the capacitor to an insulating substrate, and dissolving unnecessary portions of the metal foil. Since the method has the fourth step of removing, it is possible to form a high-performance dielectric film on a metal foil such as a copper foil conventionally used for a circuit board. A high-performance capacitor can be built into a circuit board without significantly changing the process.

A method of manufacturing a substrate with a built-in capacitor according to claim 16 includes a first step of bonding a metal foil to an insulating substrate;
A second step of forming a circuit pattern by dissolving and removing an unnecessary portion of the metal foil; a third step of forming a dielectric film at a desired position of the circuit pattern by electrophoretic electrodeposition; And the fourth step of forming a conductor layer on the surface of the dielectric film to complete the capacitor, thereby making it possible to form a high-performance dielectric film at a predetermined position on the circuit pattern. In addition, a circuit board having a high-performance capacitor built in a predetermined position on a circuit pattern can be manufactured without significantly changing the conventional circuit board manufacturing process.

According to the method for manufacturing a substrate with a built-in capacitor according to the seventeenth aspect, since a resist is used to form a conductive layer or a dielectric film at a desired position, a capacitor can be formed at an arbitrary position on a metal foil. Since the capacitor can be formed, it is possible to easily divide the capacitor in the circuit board without significantly changing the conventional circuit board manufacturing process.

In the method for manufacturing a substrate with a built-in capacitor according to the eighteenth aspect, a dielectric film is formed by using a roughened metal foil and following the rough surface shape by electrophoretic electrodeposition. Since the contact area between the film and the metal foil can be increased and the capacitance of the formed capacitor can be easily increased, a capacitor with a high capacitance density can be used without significantly changing the conventional circuit board manufacturing process. It can be built into a circuit board.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cross section of a substrate with a built-in capacitor according to a first embodiment of the present invention.

FIG. 2 is a view showing a dielectric film formed on the roughened copper foil according to the first embodiment;

FIG. 3 is a view showing a method for manufacturing the substrate with a built-in capacitor according to the first embodiment;

FIG. 4 is a schematic view of a cross section of the substrate with a built-in capacitor according to the second embodiment.

FIG. 5 is a diagram showing a method for manufacturing the capacitor-embedded substrate according to the second embodiment.

FIG. 6 is a schematic view of a cross section of the substrate with a built-in capacitor according to the fourth embodiment.

FIG. 7 is a view showing a method of manufacturing the substrate with a built-in capacitor according to the sixth embodiment;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Copper foil 2 Dielectric film 3 Aluminum layer 4 Insulating substrate 5 Interstitial via hole 7 Resist 8 Dielectric film 9 Copper layer 10 Lower copper electrode 11 Dielectric film 12 Upper copper electrode

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01G 4/18 330 H01G 1/035 E 4/20 4/06 102 (72) Inventor Kohei Shioda Kazuma, Kadoma, Osaka 1006, Matsushita Electric Industrial Co., Ltd. F term (reference) 5E082 AA20 AB01 BB02 BB05 CC05 EE03 EE05 EE23 EE30 EE31 EE35 FF05 FF14 FG03 FG06 FG26 FG34 FG36 FG37 FG38 FG39 LL15 5E346 AA43 CC08 CC21 CC32 EE13 GG19 GG19 GG19

Claims (18)

[Claims] 1. A capacitor comprising a plurality of capacitors formed by providing a dielectric film and a conductive layer between an insulating substrate and a part of a circuit pattern, wherein the dielectric films located at least on the same surface are made of the same material and Substrate with a built-in capacitor of almost the same thickness. 2. A semiconductor device comprising a plurality of capacitors formed by providing a dielectric film and a conductor layer on a part of a circuit pattern provided on an insulating substrate. Substrate with a built-in capacitor of the same material and thickness. 3. The substrate with a built-in capacitor according to claim 1, further comprising a capacitor having at least one of a circuit pattern and a conductive layer having a different area in contact with the dielectric film. 4. The substrate with a built-in capacitor according to claim 1, wherein the dielectric film has a shape following at least one of the roughened circuit pattern and the conductor layer. 5. The substrate with a built-in capacitor according to claim 1, wherein when a dielectric film of a different material is provided, it is arranged on a different surface. 6. The substrate with a built-in capacitor according to claim 1, wherein the dielectric films having different thicknesses are arranged on different surfaces. 7. The substrate with a built-in capacitor according to claim 1, wherein an interstitial via hole is provided in an insulating substrate, and the interstitial via hole is connected to a circuit pattern or a conductive layer to be electrically connected. 8. The capacitor built-in substrate according to claim 1, wherein the insulating substrate is a resin substrate, and the dielectric film is formed of an organic polymer. 9. The capacitor built-in substrate according to claim 1, wherein the insulating substrate is a resin substrate, and the dielectric film is a composite film composed of inorganic fine particles and an organic polymer. 10. The organic polymer includes an acrylic resin, an epoxy resin, a fluorocarbon resin, a polyester resin,
10. The substrate with a built-in capacitor according to claim 8, wherein the substrate is made of polyimide. 11. The capacitor built-in substrate according to claim 9, wherein the inorganic fine particles are a perovskite-type ferroelectric compound or a metal oxide. 12. The substrate with a built-in capacitor according to claim 8, wherein the conductor layer is a conductive polymer. 13. A substrate with a built-in capacitor, wherein the thickness of the dielectric film forming the capacitor is 1 μm or less. 14. A method for manufacturing a substrate with a built-in capacitor using an electrophoretic electrodeposition method for forming the dielectric film of the substrate with a built-in capacitor according to any one of claims 1 to 13. 15. A first step of forming a dielectric film on one side of a metal foil by electrophoretic electrodeposition, and forming a conductive layer at a desired position on the surface of the dielectric film to complete a capacitor. A built-in capacitor including a second step, a third step of bonding the conductor layer side of the metal foil having the capacitor to an insulating substrate, and a fourth step of melting and removing an unnecessary portion of the metal foil Substrate manufacturing method. 16. A first step of bonding a metal foil to an insulating substrate, a second step of melting and removing unnecessary portions of the metal foil to form a circuit pattern, and a step of forming a circuit pattern at a desired position on the circuit pattern. A method for manufacturing a substrate with a built-in capacitor, comprising: a third step of forming a dielectric film by an electrophoretic electrodeposition method; and a fourth step of forming a conductive layer on the surface of the dielectric film to complete a capacitor. 17. The method according to claim 15, wherein a resist is used to form the conductor layer or the dielectric film at a desired position. 18. The method of manufacturing a substrate with a built-in capacitor according to claim 15, wherein a dielectric film that follows the roughened surface is formed by electrophoresis using a roughened metal foil. Method.