JP2001036201A - Circuit board for large current and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable miniaturization while restraining increase of cost to a minimum by embedding a metal wiring in a single side or both sides of an insulating resin board, and forming a circuit. SOLUTION: A metal wiring 1 where a metal plate is worked in a desired shape by etching or the like is embedded in an insulating resin board 2. Electrode parts 4 for bonding electronic components, and a resist layer 5 are formed on the upper surfaces of the metal wiring 1 and the insulating resin board 2, and component insertion holes 3 are formed on the electrode parts 4. Leads 7 of electronic components 6 are inserted in the component insertion holes 3 from the opposite side having the metal wiring 1 embedded side and fixed with the electrode parts 4 by solders 8. Thereby a large current capacity can be ensured when wiring width of a circuit is reduced, increase in cost can be restrained to a minimum, and miniaturization is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a circuit board for high current and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the demand for miniaturization and high performance of electronic devices, there is an increasing tendency to mount electronic components on a substrate at high density. Therefore, attention has been paid to using surface-mounted electronic components without lead wires. In addition, with the progress of reflow soldering technology using cream solder or the like, the high-density mounting of electronic components on a printed circuit board has been further accelerated. However, in the field of handling large currents and high frequencies, not only is the surface mounting of electronic components delayed, but it is difficult to reduce the size of a conventional printed circuit board due to its circuit configuration. Therefore, in these fields, miniaturization of equipment using a printed circuit board has been delayed at present.

FIG. 12 is a perspective view partially showing a cross section of an example of a conventional printed circuit board. This board
This is one in which copper foil wiring 18 is arranged on the insulating resin substrate 2. As the insulating resin substrate 2, a substrate obtained by impregnating a reinforcing base material such as paper, glass, or glass nonwoven fabric with a phenol resin or an epoxy resin is often used. As is apparent from FIG. 12, in the conventional printed circuit board, the copper foil wiring 18 is arranged in a convex shape on the resin substrate 2, so that it is necessary to ensure insulation between adjacent wirings. Therefore, after forming the copper foil wiring, a resist 5 is formed as an insulating resin layer on the substrate surface. The thickness of the copper foil wiring varies depending on the use of the printed circuit board, but is generally about 35 μm.
Copper foil over 00 μm is not used.

Next, a conventional method for manufacturing a printed circuit board will be briefly described. First, the reinforcing base material is impregnated with a resin and dried. In this drying step, the curing reaction of the resin partially progresses, and the resin enters a semi-cured state (B stage) (hereinafter, the resin plate in this state is referred to as a prepreg). Next, a copper foil is attached to the surface of the prepreg. The copper foil is attached only to the surface where the circuit is required. Therefore, copper foil is stuck on one side of a single-sided board and on both sides of a double-sided board. Next, a pressure is applied to the prepreg to which the copper foil has been applied while heating (hereinafter, this operation is referred to as thermocompression bonding), and the copper foil is brought into close contact with the base material and, at the same time, the semi-cured resin is completely cured. Thereafter, a circuit is formed on the copper foil by etching. In the case of a single-sided board or a double-sided board, this is a completed product as a printed board. In the case of a multi-layer substrate, a plurality of substrates after circuit formation are stacked, thermocompression-bonded further, and integrated. Thereafter, if necessary, openings such as through holes and component insertion holes are formed using a drill or the like, and a resist (insulating resin) is printed on the surface except for an electrode portion for joining electronic components. Finally, the resist is cured by heating or irradiation with ultraviolet rays, and a printed circuit board is completed.

[0005] On the other hand, as a form that allows a large-current circuit board to be miniaturized, a resin molded board manufactured by coating a metal plate on which a circuit is formed with a resin by molding has attracted attention. Generally, a resin molded substrate is manufactured by the following procedure. First, a desired circuit is formed on a metal plate such as copper or brass by an etching method or a pressing method. The metal plate may be plated with tin or nickel in order to prevent the surface of the metal plate from being oxidized during soldering. In the case of a board on which an insertion-type electronic component is mounted, a hole for inserting the electronic component is further provided. Next, leaving the electrode part for mounting electronic components,
The metal plate on which the circuit is formed is covered with resin by molding. Various insulating resins such as a thermosetting resin represented by an epoxy resin and a thermoplastic resin represented by a liquid crystal polymer are used as the resin for molding. As a method of molding the resin,
Injection molding and transfer molding are common.

The resin molded substrate manufactured as described above has a wiring width of about 0.5 mm, whereas a conventional printed circuit board has a circuit width formed of copper foil of about 35 μm in thickness. Since the circuit is formed of a metal plate, the current capacity can be ensured even if the wiring width is reduced. In an electric circuit for high voltage, a certain insulation distance is required between wirings or between a wiring and a substrate surface in order to ensure insulation reliability. In the resin molded board, the insulation between the wirings is ensured by completely covering the metal wirings with the resin. A certain distance is maintained between the wiring and the substrate surface by the resin. The minimum value of the insulation distance to be secured is assumed in the International Electrotechnical Commission (hereinafter abbreviated as IEC) standard according to the magnitude of the voltage to be supplied. The structure of the resin molded substrate in which the metal wiring is covered with the same insulating material has a very high insulating property, and corresponds to the reinforced standard structure of the IEC standard. Therefore, the distance between the wirings can be greatly reduced as compared with the conventional printed circuit board.

[0007]

In a conventional printed circuit board, the thickness of a metal foil constituting a circuit is about 35 to 100 μm. Therefore, to configure a circuit for large current,
It is necessary to secure the current capacity by increasing the wiring width, and there is a problem that the size of the circuit board cannot be reduced. For example,
In the case of a printed circuit board having a thickness of copper foil of 35 μm, when the current value applied as in a digital signal circuit is several mA,
The wiring width can be reduced to about 0.1 mm. However, when a current of 10 A is applied as in a power supply circuit, the wiring width needs to be about 7 mm.

On the other hand, in the resin molded substrate, since the circuit is formed by a metal plate having a thickness of about 0.5 mm, the current capacity can be secured, and the wiring width in a large current portion can be reduced. Also, since the wiring is completely covered with the resin, it is possible to reduce the insulation distance between the wiring,
It is possible to reduce the size of a circuit board for a large current such as a power supply. However, to manufacture a resin molded substrate,
In general, it requires an expensive molding die. In addition, polyphenylene sulfide (hereinafter, PPS) is used as a molding resin.
That. ), There is a problem that the cost is higher than that of the printed circuit board. In addition, it is necessary to correct the mold in response to a frequently occurring circuit design change. The time required to correct the mold increases the cost and the lead time of product development.

Further, since a large current circuit board generally uses a large number of heat-generating components such as a power IC, a power transistor or a coil, it is essential to adopt a heat dissipation structure. However, conventional printed boards and resin molded boards do not have a heat radiating means, so that it is necessary to separately provide a heat radiating plate for the heat-generating component. Therefore, even if the substrate area can be reduced, it is difficult to reduce the occupied volume of the substrate including the heat sink in the product.

In view of these problems, an object of the present invention is to provide a high-current circuit board which can be miniaturized while minimizing an increase in cost and a method of manufacturing the same.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a circuit board for large currents, wherein a circuit is formed by embedding metal wiring on one or both surfaces of an insulating resin substrate. Also,
The present invention relates to a circuit board for large current, wherein a circuit is formed by embedding metal wiring on one surface of an insulating resin substrate, and a heat sink is embedded on the other surface. The present invention also relates to the large current circuit boards, wherein a portion of the surface of the insulating resin substrate on which the metal wiring is not buried and an exposed surface of the metal wiring are on the same plane. In addition, the present invention provides a method in which a metal plate on which a circuit is formed is sandwiched between two prepregs in which a glass substrate or a glass non-woven fabric substrate is impregnated with an epoxy resin and thermocompression-bonded, whereby metal wiring is formed on an insulating resin substrate. The present invention relates to a circuit board for large current, which is embedded.

The present invention also relates to the large current circuit boards, wherein the metal wiring has a projection projecting at an acute angle at a fitting portion with the insulating resin substrate. Further, the present invention relates to the circuit board for large current, wherein the insulating resin substrate is made of a material obtained by impregnating a paper base material with a phenol resin or a material obtained by impregnating a glass base material or a glass nonwoven fabric base material with an epoxy resin. . Further, the present invention relates to a method for manufacturing a circuit board for a large current, comprising a step of forming a circuit on a metal plate by an etching method or a pressing method and a step of thermocompression bonding the metal plate to a prepreg.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The circuit board for large current according to the present invention is characterized in that a circuit is formed by embedding metal wiring on one or both sides of an insulating resin substrate. If the metal wiring is arranged only on one side of the resin board, the heat sink must be buried on the other side. Is preferred because there is no That is, in the large-current circuit board, a circuit is formed in a state where metal wiring or a heat sink is fitted into a concave portion provided on the surface of the resin substrate, or a heat sink is provided. Note that a metal plate is preferably used as the heat radiating plate.

The metal wiring has a thickness of 0.07 to 1 m.
m, more preferably 0.07-0.5 mm, especially 0.12
It is preferably about 0.5 mm. Since the metal wiring has the above-described thickness, a large current capacity can be secured even if the wiring width of the circuit is reduced. As a result, the size of the large current circuit board can be reduced. Furthermore, since the metal wiring is embedded in the resin substrate, there is an advantage that the metal wiring can be fixed more firmly to the resin substrate than the copper foil wiring of the conventional printed circuit board.

It is preferable that the metal wiring has a projection projecting at an acute angle at a fitting portion with the insulating resin substrate in that the metal wiring can be embedded more firmly in the resin substrate. The protrusion protrudes in the direction in which the metal wiring travels when the metal wiring is embedded in the resin substrate. It is preferable that the protrusion is in a state where the edge of the metal wiring is sharpened in the traveling direction. By providing such protrusions, when a nonwoven fabric base material or the like is used as a raw material of a resin substrate in a manufacturing process of a large current circuit board described later, fibrous materials such as a nonwoven fabric are cut or efficiently pushed away. The metal wiring can be buried in the resin substrate.

In the large current circuit board, a part of the metal board is exposed to the outside. Therefore, when a metal plate on which a circuit is formed is covered with a molding resin as in a conventional resin molded substrate, there is no need to devise an electrode portion so as not to be covered with the resin.

As the insulating resin substrate used for the large current circuit board, an inexpensive resin material such as a phenol resin and an epoxy resin used for a conventional printed circuit board can be used. These resins are impregnated into a paper base, glass base, glass nonwoven base, etc. to form a prepreg that has partially advanced the curing reaction. It becomes an insulating resin substrate having high performance.

In the large current circuit board, the portion of the surface of the insulating resin substrate on which the metal wiring is not buried and the exposed surface of the metal wiring are on the same plane. It is preferable because it is easy to secure and the production method is easy.

In manufacturing the large current circuit board,
A molding die is not required unlike a conventional resin molded substrate.
Therefore, as compared with the resin molded substrate, the manufacturing cost can be reduced, and the lead time for product development can be shortened.

Specifically, first, a circuit is formed on a metal plate by an etching method or a pressing method. At this time, it is preferable in a manufacturing process to process a single metal plate to form a plurality of wirings and form a perforated metal plate in a state where the wirings are connected by connecting portions.

Next, the metal plate on which the circuit is formed is overlapped with the prepreg and thermocompression-bonded. At this time, for example, using a single prepreg, installing a metal plate on one side thereof, and thermocompression bonding using a general device, the metal wiring is pushed from the surface of the resin substrate softened by heat, and at the same time, the resin component The curing reaction proceeds. As a result, a circuit is formed with the metal wiring buried on one side of the resin substrate. Thereafter, if necessary, operations such as applying a resist to the substrate surface and curing the substrate are performed, thereby completing a large-current circuit board. The method is also advantageous in that a prepreg containing a nonwoven fabric or the like that cannot be used in injection molding or the like can be used as a raw material of a resin base material.

In the above method, when a metal plate on which a circuit is formed is sandwiched between two prepregs and thermocompression-bonded, another circuit board for large current of the present invention in which metal wiring is embedded in a resin substrate can be obtained. The circuit board for high current can use a prepreg containing a paper base, a glass base, a glass nonwoven base, etc. as a raw material. Excellent bondability with In addition, the circuit board for high current of the present invention is characterized in that the resin constituting the prepreg has an adhesive property to the metal plate, so that the metal plate and the resin are completely adhered to each other, and the reliability for moisture absorption and water absorption is high. It is different from the conventional resin molded substrate.

Next, the present invention will be described by way of specific embodiments with reference to the drawings. Embodiment 1 FIG. 1 is a perspective view showing a cross section of a part of a large current circuit board according to the present embodiment. A metal wiring 1 obtained by processing a metal plate into a desired shape by etching or the like is used as an insulating resin substrate 2
Buried in The upper surface of the metal wiring 1 and the upper surface of the resin substrate 2 are on the same plane. Metal wiring 1 and resin substrate 2
An electrode part 4 and a resist layer 5 for joining electronic components are formed on the upper surface of the substrate. A component insertion hole 3 is formed in the electrode portion 4. FIG. 2 is a longitudinal sectional view of the substrate of FIG. 1 when the electronic component 6 with leads is mounted, cut along a plane passing through the centers of the two electrode portions 4. The lead 7 of the electronic component 6 is inserted into the component insertion hole 3 from the side opposite to the side where the metal wiring 1 is buried, and is fixed by the solder 8 at the electrode portion 4.

This substrate is manufactured by the following procedure. First, a base material such as a glass nonwoven fabric is impregnated with a resin such as an epoxy resin, and a dried prepreg 9 and a metal plate 12 on which a circuit is formed are overlapped with each other, as shown in FIG.
It rests on the press plate 11 of a hot press. The outer shape of the prepreg 9 is made larger than the metal plate 12. At this time, between the press plate 11 and the prepreg 9 and the metal plate 12,
A release paper 10 for preventing the prepreg 9 and the press plate 11 from adhering to each other is disposed. In this state, the heat press is operated to heat-press the metal plate 12 and the prepreg 9 to embed the metal plate 12 in the resin substrate and simultaneously cure the resin component of the prepreg. The outer shape of the circuit board obtained at this time is slightly larger than before pressing due to the spread of the resin. After trimming to the required dimensions,
The component insertion hole 3 is opened with a drill or the like. Generally, the metal plate 12 has a connecting portion connecting a plurality of wirings. Since electrical connection is not required at the connecting portion, the connecting portion is also cut with a drill or the like.

Since the metal wiring is exposed on the surface of the obtained circuit board, insulation between the wirings is insufficient. Therefore, a resist 5 is printed on the circuit board except for the electrode section 4. At this time, a silk screen or the like can be used. As the resist 5, a photosensitive resin generally used for a conventional printed circuit board can be used. After printing, the resist 5 is cured in an ultraviolet curing furnace or the like, and the circuit board is completed.

Embodiment 2 FIG. 4 is a cross-sectional view of a large current circuit board according to this embodiment. On both surfaces of the insulating resin substrate 2, metal wirings 1a and 1b are respectively buried, and a resist layer 5 is formed in portions other than portions used as electrode portions.

This substrate is manufactured by the following procedure. As shown in FIG. 5, the prepreg 9 is placed on the press plate 11 of the hot press with the metal plates 12a and 12b having circuits formed therebetween. At this time, the release paper 10 is arranged between the press plate 11 and each metal plate. Hereinafter, a circuit board is manufactured in the same procedure as in the first embodiment. in this way,
By forming a circuit in which the metal wirings 1a and 1b are embedded on both sides of the substrate, the substrate can be further reduced in size.

Embodiment 3 FIG. 6 is a sectional view of a large current circuit board according to this embodiment. A metal wiring 1 is embedded in an insulating resin substrate 2, and a component insertion hole 3 is formed in an electrode portion 4 for mounting an electronic component.

This substrate is manufactured by the following procedure. As shown in FIG. 7, a metal plate 12 on which a circuit is formed is sandwiched between two prepregs 9a and 9b and left on a press plate 11 of a hot press. At this time, the release paper 10 is arranged between the press plate 11 and each prepreg. Hereinafter, a circuit board is manufactured in the same procedure as in the first embodiment. However, since the metal plate 12 is inside the resin substrate 2, the component insertion holes 3
The opening 4 does not form the electrode portion 4 for component connection. Therefore, an opening 13 is provided around the component insertion hole 3 to reach the surface of the electrode portion 4. In this state, since the metal wiring 12 exists inside the circuit board, it is not necessary to apply a resist.

Normally, the voltage in a circuit to which a current of 10 A is applied is 100 V. In this case, the minimum inter-wiring distance defined by the IEC standard of the conventional printed circuit board is 1.8.
mm. On the other hand, since the circuit board according to the present embodiment has a reinforced insulation structure, the minimum distance between wirings defined by the IEC standard is 0.4 mm. Actually, the distance between wirings depends on the thickness of the metal plate to be used.
It is about 6 mm. Therefore, the wiring width can be reduced to 1/7 the size and the distance between wirings can be reduced to 1/3 as compared with the case where a conventional printed circuit board is used.

Fourth Embodiment FIG. 8 is a cross-sectional view showing a front-mounted electronic component mounted on a large-current circuit board according to the present embodiment. The metal wiring 1 is buried on one side of the resin substrate 2, and the resist layer 5 except for the electrode portion 4 is formed.
Are formed. The electrode unit 4 includes a surface-mounted electronic component 15
Has been implemented. On the other surface of the resin substrate 2, a heat radiating plate 14 such as a copper plate is embedded.

This substrate is manufactured by the following procedure. As shown in FIG. 9, the prepreg 9 and the metal plate 12 on which the circuit is formed are overlapped, the heat radiating plate 14 is arranged on the opposite side to the metal plate 12, and is left on the press plate 11 of the hot press. . The heat radiating plate 14 is arranged at a position facing an electrode portion on which a heat radiating electronic component is mounted. The release paper 10 is disposed between the press plate 11 and the metal plate 12 and between the press plate 11 and the heat radiating plate 14. Hereinafter, a circuit board is manufactured in the same procedure as in the first embodiment. In this embodiment, since a front-mounted electronic component is used, a component insertion hole is not required. Since the heat radiating plate 14 is disposed at the portion facing the electrode portion to which the heat-generating component is joined, the heat of the component is radiated from the heat radiating plate 14 via the resin substrate, and the temperature of the circuit board is prevented from rising. it can. Further, since there is no need to separately attach a heat sink, space for the heat sink is not required, and the product can be further reduced in size.

Fifth Embodiment In this embodiment, a large current circuit board is manufactured by providing a metal wiring of a metal plate on which a circuit is formed with a projection projecting at an acute angle. FIG. 10 is a cross-sectional view of a large-current circuit board without a resist layer according to the present embodiment. The metal wiring 1 is embedded in the resin substrate 2. Protrusions 17 projecting at acute angles are provided at both ends of the wiring 1. The projecting portion 17 can be formed by hitting a central portion of a wiring surface of the metal plate on which a circuit is formed to be projected with a punch or by performing press working.

The effect of the present embodiment will be described by taking as an example the case where a prepreg in which a paper base material is impregnated with a phenol resin is used as a resin substrate. When a metal plate having no protrusion is embedded in the prepreg, as shown in FIG. 11, the paper base material in the prepreg is pushed down to the lower side of the wiring 1 and the paper base around the wiring 1 embedded in the base material is Only the resin component 16 impregnated in the base material may exude. This is because the fibers are not cut when the wiring 1 is embedded because the density of the fibers of the paper base is high. In such a case, the adhesion strength between the resin substrate and the metal wiring may decrease. On the other hand, when the metal provided with the protruding portion is buried, as shown in FIG. 10, the paper base under the wiring 1 is pushed down, but the resin component 16 exudes near the side surface of the wiring 1. Almost never. This is because the protrusions 17 cut the fibers of the paper base material. As described above, according to the present embodiment, the vicinity of the side surface of the wiring buried in the resin substrate can be suppressed from being only the resin component, the contact area between the base material and the wiring increases, and the resin substrate And the metal wiring can be secured tightly.

[0035]

Next, the present invention will be described more specifically with reference to examples. Example 1 An inverter circuit was manufactured as a circuit board having the configuration shown in FIG. A 1.7 mm-thick prepreg was prepared by impregnating a glass nonwoven fabric substrate with an epoxy resin and drying. In addition, a wiring pattern was formed by pressing a copper plate having a thickness of 0.5 mm by pressing, and used as a metal plate on which a circuit was formed. The wiring width of the circuit was 1 mm. As shown in FIG. 3, the prepreg and the metal plate were overlapped, a release paper was also arranged, and thermocompression bonding was performed. At the same time as the metal plate was embedded in the prepreg, the prepreg was cured. The prepreg used was larger by 20 mm in length and width than the metal plate. The conditions of thermocompression bonding are as follows: temperature 175 ° C, pressure 15k
g / cm ² . After leaving for 30 minutes in this state,
It was gradually cooled for 30 minutes while applying pressure, and then the press was lowered to take out the circuit board.

The total thickness of the obtained circuit board is 1.5
mm, and the outer shape was slightly larger than before pressing due to the spread of the resin. The outer periphery was cut off to the required dimensions, and a part insertion hole was opened with a drill. Unnecessary connecting portions of the circuit were also cut. Next, a resist was printed on the substrate surface excluding the electrode portion by screen printing, and cured in an ultraviolet curing oven to form a resist layer, thereby completing a circuit board. This inverter circuit was designed as a circuit having a maximum applied current of 10A.

The same circuit pattern was formed on a conventional paper base material impregnated with a phenol resin using a copper foil having a thickness of 35 μm.
To operate stably at an ambient temperature of 25 ° C, 7
A wiring width of mm was required. When the wiring width was set to 3 mm, the wiring was blown out after several seconds. Note that the circuit board of the present embodiment could have a metal wiring width of 1 mm, so that the size of the circuit board was reduced to 1 / the size of the conventional printed board.
7 was achieved.

Example 2 A circuit board having the structure shown in FIG. 4 was manufactured. The prepreg used in Example 1 was prepared. Further, two copper metal plates used in Example 1 were prepared. FIG.
As shown in (2), a prepreg was sandwiched between two metal plates, a release paper was further disposed, and the plate was allowed to stand on a press plate of a hot press. Then, thermocompression bonding was performed under the same conditions as in Example 1.

The thickness of the obtained circuit board was 1.6 mm. After cutting off the outer periphery to the required dimensions, unnecessary connecting portions were cut. In this embodiment, the circuit is formed by embedding metal wiring on both sides of the circuit board.
A circuit board having a circuit density twice as high as that of the circuit board described above was obtained.

Example 3 A circuit board having the structure shown in FIG. 6 was manufactured. Two 0.8 mm thick prepregs prepared by impregnating a glass nonwoven fabric with an epoxy resin were prepared. As shown in FIG. 7, the same copper metal plate as in Example 1 was sandwiched between two prepregs, a release paper was further disposed, and the plate was allowed to stand on a press plate of a hot press. Then, thermocompression bonding was performed under the same conditions as in Example 1.

The thickness of the obtained substrate was 1.5 mm. After cutting off the outer periphery to the required size, the component insertion hole was opened with a drill. After cutting unnecessary connecting portions, openings were formed around the component insertion holes. As a result, it was possible to obtain a circuit board having a reinforced insulation structure according to the IEC standard in which a metal plate constituting a circuit was completely covered with a resin.

Example 4 A circuit board having the structure shown in FIG. 8 was manufactured. A prepreg having a thickness of 1.7 mm in which a glass nonwoven fabric base material was impregnated with an epoxy resin, and a radiator plate in which a surface of a copper plate having a thickness of 0.5 mm was plated with Ni were prepared. FIG.
As shown in (1), the same metal plate, prepreg, and heat radiating plate as in Example 1 were overlaid, release paper was further disposed, and the plate was allowed to stand on a press plate of a hot press. Then, thermocompression bonding was performed under the same conditions as in Example 1. Next, a resist was printed on a portion of the surface on which the metal plate was buried except for the electrode portion in the same manner as in Example 1, and cured in an ultraviolet curing furnace to form a resist layer.

The total thickness of the obtained circuit board is 1.6.
mm. After cutting off the outer periphery to the required dimensions, unnecessary connecting portions were cut. Then, a power transistor was joined to the electrode portion. The obtained circuit board has a smaller occupied space than the conventional circuit board because the heat sink is integrally formed in the board.

Example 5 Using the same metal plate as in Example 1, a circuit was formed so that the wiring width was 1 mm. Then, the center of one side of the wiring constituting the circuit was dented by hitting with a punch, and the end of the wiring was projected at an acute angle.
The difference in height between the wiring projection and the flat portion was about 0.1 mm. The surface of the metal plate on which the projections were formed was overlapped with a prepreg obtained by impregnating a paper base material with a phenol resin, and allowed to stand on a press of a hot press. The thermocompression bonding was performed under the same conditions as in Example 1. Thereafter, a circuit board was manufactured in the same procedure as in Example 1. The bonding strength between the wiring of the obtained circuit board and the board was determined in Example 1. Improved than the circuit board that did.

[0045]

As described above, according to the present invention, a high-performance, large-current circuit board can be manufactured at low cost and its size can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a cross section of a part of a large-current circuit board according to an embodiment of the present invention in which a circuit is formed by embedding metal wiring on one surface of an insulating resin substrate.

FIG. 2 is a cross-sectional view of a large-current circuit board according to an embodiment of the present invention in which a circuit is formed by embedding metal wiring on one surface of an insulating resin substrate in a state where electronic components are mounted on electrode portions. .

FIG. 3 is a schematic view showing an arrangement of materials when performing thermocompression bonding used for explaining a manufacturing process of the large current circuit board.

FIG. 4 is a cross-sectional view of a large-current circuit board according to an embodiment of the present invention in which metal wiring is embedded on both surfaces of an insulating resin substrate to form a circuit.

FIG. 5 is a schematic diagram showing an arrangement of materials used for explaining a manufacturing process of the circuit board for large current when performing thermocompression bonding.

FIG. 6 is a cross-sectional view of a circuit board for large current according to one embodiment of the present invention in which a metal plate on which a circuit is formed is sandwiched between two prepregs and thermocompression-bonded.

FIG. 7 is a schematic view showing an arrangement of materials used for explaining a manufacturing process of the large current circuit board when performing thermocompression bonding.

FIG. 8 shows a state in which a circuit is formed by embedding metal wiring on one surface of an insulating resin substrate, a metal plate for heat dissipation is embedded on the other surface, and a front-mounted electronic component is mounted on an electrode portion. It is sectional drawing of the circuit board for large electric current which concerns on one Embodiment.

FIG. 9 is a schematic diagram showing an arrangement of materials when performing thermocompression bonding used for explaining a manufacturing process of the large current circuit board.

FIG. 10 is a cross-sectional view of a large-current circuit board according to an embodiment of the present invention when a wiring portion of a metal plate on which a circuit is formed has a projection projecting at an acute angle.

FIG. 11 is a cross-sectional view of a large current circuit board according to an embodiment of the present invention in a case where a wiring portion of a metal plate on which a circuit is formed does not have a projection projecting at an acute angle.

FIG. 12 is a perspective view showing a cross section of a part of a conventional printed circuit board.

DESCRIPTION OF SYMBOLS 1 Metal wiring 1a Metal wiring 1b Metal wiring 2 Insulating resin substrate 3 Component insertion hole 4 Electrode part 5 Resist layer 6 Electronic component 7 Electronic component lead 8 Solder 9 Prepreg 9a Prepreg 9b Prepreg 10 Release paper 11 Press plate Reference Signs List 12 Metal plate on which circuit is formed 12a Metal plate on which circuit is formed 12b Metal plate on which circuit is formed 13 Opening 14 Heat sink 15 Surface mounted electronic component 16 Resin component 17 Projection 18 Copper foil wiring

Continued on front page (72) Inventor Shigeru Kondo 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term (reference) in Matsushita Electric Industrial Co., Ltd. 5E339 AB02 AD01 BC01 BD06 BE11 5E343 AA02 AA13 BB21 BB67 DD55 DD62 GG11

Claims (7)

[Claims] 1. A circuit board for high current, wherein a circuit is formed by embedding metal wiring on one or both sides of an insulating resin substrate. 2. A circuit board for large current, wherein a circuit is formed by embedding metal wiring on one surface of an insulating resin substrate, and a radiator plate is embedded on the other surface. 3. The large-current circuit board according to claim 1, wherein a portion of the surface of the insulating resin substrate on which the metal wiring is not embedded and an exposed surface of the metal wiring are on the same plane. 4. A metal plate on which a circuit is formed is sandwiched between two prepregs in which a glass substrate or a glass non-woven fabric substrate is impregnated with an epoxy resin and thermocompression-bonded, thereby embedding metal wiring in an insulating resin substrate. A large current circuit board characterized by the following. 5. The large current circuit board according to claim 1, wherein the metal wiring has a projection projecting at an acute angle at a fitting portion with the insulating resin substrate. 6. The insulating resin substrate according to claim 1, wherein the insulating resin substrate is made of a material obtained by impregnating a paper base material with a phenol resin or a material obtained by impregnating a glass base material or a glass nonwoven fabric base material with an epoxy resin. The circuit board for large current as described. 7. A method for manufacturing a large-current circuit board, comprising: a step of forming a circuit on a metal plate by an etching method or a pressing method; and a step of thermocompression bonding the metal plate to a prepreg.