JP3509315B2 - Circuit board manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board used in devices having a large current capacity power supply and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a large current circuit board in which a circuit pattern for signals is formed on one surface of an insulating substrate and a circuit conductor for large current is formed on the other surface. This kind of large current circuit board is generally formed by pasting thick copper foil for a large current circuit and pattern etching.

However, in such a large current circuit board, the thickness of the copper foil is limited to a thickness that can be etched. Therefore, in the case of a large current circuit, the conductor width must be increased in order to increase the current capacity. Therefore, it is difficult to make the circuit compact.

When forming a through hole in a circuit conductor for large current, a conductor layer is formed by electroless plating on the inner surface of the hole formed in the insulating substrate, as in the case of a normal signal circuit pattern. However, since it is difficult to increase the thickness of the conductor layer in such a through hole, a large current cannot be passed.

Therefore, many proposals have been made to solve the above inconveniences. FIG. 11 shows, for example, JP-A-63
FIG. 12 is a plan view of a wiring board provided with a large current circuit and a signal circuit described in Japanese Patent Laid-Open No. 237495, and FIG. 12 is a sectional view thereof. In FIG. 12, 1 is an insulating substrate made of glass epoxy or the like.

Further, 2A and 2B are signal circuit conductors provided on the front surface and the back surface of the insulating substrate 1, and 3 is a circuit conductor for large current provided on one surface of the insulating substrate 1.

The circuit conductors 2A and 2B for signals are the same as in the conventional case.
It is formed by etching copper foils used for normal signal circuits attached to both surfaces of the insulating substrate 1 into desired patterns, and the circuit conductors 2A on both surfaces,
A through-hole portion 4 for conducting 2B is also formed on the inner surface of the hole by plating.

On the other hand, as the circuit conductor 3 for large current, for example, a copper plate having a thickness of about 1 mm is punched into a required pattern, and the whole surface is subjected to solder plating or tin plating on the insulating substrate 1. It is formed by soldering.

The through hole portion 5 of the circuit conductor 3 for large current is formed into a cylindrical projection 6 by squeezing out a predetermined portion of the circuit conductor 3 in advance into a cylindrical shape by burring and then forming the cylindrical shape. It is formed by inserting the projection 6 into the hole of the insulating substrate 1.

FIG. 13 is a sectional view showing a conventional high-current circuit board disclosed in Japanese Patent Laid-Open No. 3-21095, in which 7 is a prepreg sheet and 8 is a clear resin. By punching a copper plate or the like, a circuit conductor for large current is formed, and in particular, a punched circuit pattern in which adjacent circuit conductors are connected by a thin bridge is formed.

Here, the prepreg sheet 7 is made by impregnating glass fiber with a thermosetting resin such as epoxy resin and semi-curing it. The prepreg sheet 7 is placed on a prepreg sheet 7 having a plurality of punched circuit patterns laminated and heated. By applying pressure, the prepreg sheet 7 is cured to form an insulating substrate, and a substrate having a punched circuit pattern embedded therein is formed on the insulating substrate. Further, by cutting the bridge portion connecting the adjacent circuit conductors as described above, a circuit board for large current is obtained.

[0012]

Since the conventional large-current circuit board is constructed as described above, in order to increase the current capacity, which is one of the conventional problems, the conductor width must be increased. It can be dealt with by using a copper plate as described above, but since it is fixed to the insulating substrate by soldering, for example, when soldering on the entire surface, the expansion coefficient of the conductor and the substrate during cooling is reduced. There was a problem that warpage might occur due to the difference.

Further, there is a problem that the conductor needs to be subjected to burring for forming the through hole.
Furthermore, since the circuit conductor 3 for large current is soldered on the insulating substrate 1, the solder is projected from the substrate surface,
There is a problem in that the flatness with other signal circuits cannot be obtained, and thus the component mounting by the robot becomes complicated.

On the other hand, according to Japanese Patent Laid-Open No. 3-21095 of FIG. 13, the circuit board is formed by heating and pressurizing the punched circuit conductor and the prepreg sheet 7 with a hot press, so that the surface of the insulating substrate is made flat. Although the problems such as the solder popping out can be solved by such a method, in such a method, the circuit conductor 3 for large current is
Since the prepreg sheet 7 for interlayer insulation is pressed against the circuit conductor 3, the clear resin 8 shown in the figure seeps out from the periphery of the circuit conductor 3 for a large current at the time of pressing, and the temperature rises during energization, so that the circuit conductor 3 and the clear conductor 8 clear. Interface with 8 layers of resin,
Alternatively, there is a problem that cracks may be induced at the interface between the eight layers of clear resin and a circuit conductor (not shown) for signals provided on the surface of the clear resin.

Therefore, with such a method, it is possible to make the surface of the insulating substrate flat, but it is impossible to mix the signal circuit and the large current circuit on the same surface due to the cracks. There is a drawback that

Although not shown in the figure, in this example, a through hole for a large current is formed by plating the inner wall of the conductive hole and then melting and embedding solder in the hole. Since the solder filled in the holes contracts during cooling, there is a risk that the plating layer pre-electrolessly plated on the inner wall of the through hole will peel off.

Further, in order to position the circuit conductors, adjacent circuit conductors are connected by a thin bridge to form a punched circuit pattern. Therefore, the work of cutting the bridge after the lamination molding occurs, and the adverse effect of oxidation of the cut portion occurs. There were problems such as concerns.

The present invention has been made in order to solve the above problems, and does not require troublesome soldering of a circuit conductor to an insulating substrate, and furthermore, heats a punched circuit pattern on a prepreg sheet, An object of the present invention is to obtain a circuit board which does not seep out of the clear resin during pressurization and can prevent the occurrence of electrical defects .

Another object of the present invention is to obtain a circuit board in which the creepage distance between the circuit conductors on the same insulating substrate can be increased and the insulating characteristics of the circuit conductors can be greatly improved.

Another object of the present invention is to obtain a circuit board which can improve the heat dissipation of the circuit conductor .

Another object of the present invention is to obtain a method for manufacturing a circuit board which can avoid the problems caused by conventional solder and clear resin .

Further , according to the present invention , by using a dummy plate to make the circuit conductor portion the same thickness as the insulating substrate, it is possible to heat and pressurize the insulating substrate and the prepreg sheet. An object of the present invention is to obtain a method for manufacturing a circuit board by removing the dummy plate so that the creepage distance between the circuit conductors in the insulating board can be sufficiently secured.

Another object of the present invention is to obtain a method for manufacturing a circuit board, which allows a part of the circuit conductor to be exposed on the insulating board .

[0024]

According to a first aspect of the present invention, there is provided a circuit board manufacturing method, wherein a pattern of a circuit conductor is provided on an insulating substrate.
-Shaped punching groove is formed in the punching groove.
From the thinner circuit conductor and its depth, the thickness of the circuit conductor
After inserting a dummy plate with good releasability,
Laminate the board on the prepreg sheet and add them together.
The circuit conductor is placed in the insulating substrate by applying heat and pressure.
And then remove the dummy plate from the punching groove.
It is something that is done.

In the method for manufacturing a circuit board according to the second aspect of the present invention, a punching groove having a pattern shape of the circuit conductor is formed in the insulating substrate, and a circuit conductor thicker than the depth is inserted into the punching groove, and the circuit is formed. After covering the part where the conductor protrudes from the insulating substrate with a punching groove of a dummy plate having good releasability that is equal to the thickness of this part, put a prepreg sheet on the side of the insulating substrate opposite to the covered side. By laminating and heating and pressurizing them together, a part of the circuit conductor is embedded in the insulating substrate, and the dummy plate is separated and removed from the circuit conductor .

[0026]

A method of manufacturing a circuit board according to the invention of claim 1
Place the circuit conductor and dummy plate in the punched groove of the insulating substrate.
To make the upper surface of the dummy plate and the upper surface of the insulating substrate uniform.
By doing so, heating and pressurizing the insulating substrate and the prepreg sheet
Sufficiently embed the circuit conductor in the punched groove of the insulating substrate
However, after removing the dummy board, the circuit conductors are sufficient in the insulating substrate.
It is possible to secure a large creepage distance.

In the method of manufacturing a circuit board according to the second aspect of the present invention, a part of the circuit conductor is exposed above the insulating substrate, and the punched groove of the dummy plate is once covered on the exposed portion to form a prepreg sheet. After the lower part of the circuit conductor is embedded in the insulating substrate by heating and pressurizing with the insulating substrate, the dummy plate is removed, so that the circuit conductor exposed on the insulating substrate and having good heat dissipation efficiency can be installed .

[0028]

EXAMPLES Reference Example 1 . Hereinafter, reference examples of the present invention will be described with reference to the drawings. In FIG. 1, 1A is an insulating substrate made of glass epoxy resin or the like, 3 is a circuit conductor for large current embedded in the insulating substrate 1A, and is made of a copper plate having a thickness of about 0.5 to 3.0 mm. .

In this reference example , for example, 500 to 150
A copper plate having a thickness of 2.3 mm capable of passing a current of 0 A and having a chamfer of a radius of 0.5 mm is used.

The copper plate used as the circuit conductor 3 is a thick copper foil made of electrolytic copper or rolled copper, JIS-C310.
2, flat wire standardized by C3101, etc., or JIS
-C1100, C1220, etc. are standard copper plates.

Reference numeral 7 is a prepreg sheet heated and pressed on both sides of the insulating substrate 1A, and these are integrated to form a large current circuit substrate.

FIG. 2 is a plan view of the insulating substrate 1A which constitutes the large current circuit board. The insulating substrate 1A is preliminarily formed with a punching groove 9 having a circuit pattern shape for large current.

FIG. 3 is a plan view showing a state in which the circuit conductor 3 for large current is inserted into the punching groove 9 shown in FIG.

Next, a method for manufacturing the large current circuit board of this reference example will be described. FIG. 2 shows an insulating substrate 1A in which a punching groove 9 for a large current circuit is formed. As shown in FIG. 3, a preformed circuit conductor 3 of the same shape is inserted into this punching groove 9.

On the upper and lower surfaces of the insulating substrate 1A thus constructed, the prepreg sheet 7 which becomes an insulating layer after being heat-cured is laminated. A plurality of prepreg sheets 7 are laminated according to the desired thickness of the surface insulating layer.

If it is desired to make the surface insulating layer thick,
Another insulating substrate may be prepared in advance, and a prepreg sheet may be sandwiched between the circuit conductor and another insulating substrate to be laminated.

Positioning of the pattern is performed by a pin lamination method using pins of a jig. For this reason, all of the laminated materials have holes for positioning, and the insulating substrate 1A and the prepreg sheet 7 are stacked and set while passing pins as jigs through the positioning holes (not shown).

Further, in this state, heating and pressurization by hot pressing are performed. For example, heating and pressurization are performed under known press conditions for FR-4.

As a result, the prepreg sheet 7 is cured to become a part of the insulating substrate, and the lamination molding process is completed in a state where the circuit conductor 3 is hidden by the insulating substrate 1A to obtain a large current circuit substrate.

In the circuit in which the circuit conductor is mounted by using the prepreg sheet 7, by forming as described above, the clear resin layer formed around the circuit conductor is not generated unlike the conventional case, and the mechanical heat is generated. Or due to the heat generated when energized,
It is possible to prevent cracks, peeling, and the like from occurring at the interface between the circuit conductor 3 and the clear resin.

By hiding the circuit conductor 3, contaminants such as dust, moisture, salt and gas do not come into direct contact with the circuit conductor, so that electrical defects due to oxidation of the circuit conductor can be prevented. Furthermore, since the circuit conductor is covered with the insulating substrate, it is excellent in insulating properties from other parts.

Further, the circuit for large current is positioned by inserting the circuit conductor having the same thickness into the insulating substrate 1A in which the pattern shape of the circuit conductor 3 is punched out.
Unlike the conventional example, there is no work of cutting the bridge after laminating, and therefore there is no adverse effect due to oxidation of the cut portion. Also, because it is no longer necessary to solder the circuit conductor to the board,
Warpage during cooling can be avoided.

Reference Example 2. In the above reference example 1, the case where one insulating substrate 1A is used is shown, but as shown in FIG.
A circuit board using the insulating substrates 1A, 1B, 1C, 1D can be used. In this case, the insulating substrates 1A to 1D are used.
In each case, a punching groove 9 is punched in a pattern shape of a circuit conductor at a predetermined position.

First, the same circuit conductor 3 as in the above-mentioned reference example is inserted into each punching groove 9 formed in the insulating substrates 1A to 1D, and the prepreg sheet 7 (this reference example) is inserted between these insulating substrates 1A to 1D. Then, 0.2 mm × 5 sheets are put in to obtain a withstand voltage of 4.5 Kv) and stacked.

Subsequently, in this state, the prepreg sheet 7 is cured by heating and pressurizing with a hot press, and the lamination molding is completed. The large-current circuit board formed in this manner can be used as a large-current multilayer board in the same manner as an ordinary multilayer printed wiring board.

Example 1. Figure 5 is a process diagram showing a method of manufacturing a circuit board according to the first embodiment of the present invention. In the figure, 10 is a dummy plate made of releasability good plastic. The same parts as those in FIG. 3 are designated by the same reference numerals, and the duplicated description will be omitted.

First, in the punching groove 9 having a circuit pattern shape for large current formed on the insulating substrate 1A, the circuit conductor 3 thinner than the depth of the punching groove 9 and the thickness of the circuit conductor 3 from the depth of the punching groove 9 are formed. The dummy plate 10 made of a material having a good releasability and having a thickness less than that of the insulating board is inserted to have the same thickness as the insulating substrate.

Next, the insulating substrate 1A is laminated on the prepreg sheet 7, the insulating substrate 1A and the prepreg sheet 7 are heated and pressed to embed the circuit conductor 3 in the insulating substrate 1A, and then the dummy plate is formed. 10 is removed so that the upper surface of the circuit conductor 3 faces the lower part in the insulating substrate 1A.

Since the upper surface of the circuit conductor 3 is formed so as to face the lower portion of the insulating substrate 1A, the creeping insulation distance from other circuit conductors on the same insulating substrate 1A can be made longer. The distance from other circuit conductors can be minimized.

Also, when the circuit board for large current according to this embodiment is used with two circuit conductors 3 facing each other, the conductor portions do not contact each other, so that the electrical reliability is improved. To do.

Example 2. FIG. 6 is a process drawing showing another method for manufacturing a circuit board according to the second embodiment of the present invention. In this embodiment, the circuit conductor 3 has a shape protruding upward from the upper surface of the insulating substrate 1A.

First, the circuit conductor 3 is formed in the punching groove 9 having a circuit pattern shape for a large current formed on the insulating substrate 1A, and the circuit conductor 3A has a shape thicker than the depth of the punching groove 9.
Insert.

Next, the circuit conductor 3A is connected to the insulating substrate 1.
A punching groove 10a is formed on a dummy plate 10A made of plastic having good releasability, which corresponds to the thickness protruding from A, in accordance with the pattern shape of the circuit conductor 3A, and the formed punching groove 10a is formed in the circuit. It is laminated on the upper surface of the insulating substrate 1A so as to be inserted into the conductor 3A, and these are further laminated on the prepreg sheet 7.

Subsequently, the insulating substrate 1A and the prepreg sheet 7 are heated and pressed to attach the circuit conductor 3A to the insulating substrate 1A.
After embedding it inside, the dummy plate 10A is removed. By doing so, the circuit conductor 3A is exposed on the insulating substrate 1A, so that a circuit board having good heat dissipation can be obtained.

Reference Example 3 7A to 7D are process diagrams showing a method of manufacturing a circuit board according to a third reference example of the present invention. In this reference example , the punching groove 10a having the pattern shape of the circuit conductor 3 formed on the dummy plate 10A made of a plastic having a good releasability is formed on the insulating substrate 1A.
Of the circuit conductor 3 formed on the dummy plate 10A in the pattern-shaped punching groove 10a formed in the dummy plate 10A with a thickness and shape similar to the depth of the punching groove 10a. Insert. continue,
The dummy plate 10A, the prepreg sheet 7, and the insulating substrate 1
After heating and pressurizing A and molding the circuit conductor 3 on the insulating substrate, the dummy plate 10A is removed. By doing so, the circuit conductor 3 is exposed on the board, and a circuit board having good heat dissipation can be obtained.

Reference Example 4. FIG. 8 is a sectional view showing a circuit board according to Reference Example 4 of the present invention. In this reference example , first, the circuit conductors 31, 32 having the same thickness and shape as the depth of the punching groove 9 are formed in the patterning punching grooves 9 of the circuit conductors 31, 32 formed on the insulating substrates 1A, 1B. Is inserted to form two single-sided circuit boards P.

Next, the insulating substrates 1A and 1B in which the circuit conductors 31 and 32 are inserted are laminated so as to sandwich the prepreg sheet 7, and the insulating substrates 1A and 1B and the prepreg sheet 7 are heated and pressed so that the circuit conductor 31 is formed. , 32 are embedded in the insulating substrates 1A and 1B.

That is, the prepreg sheet 7 is laid on the insulating substrate 1A with the side where the circuit conductor 32 faces the outside facing downward, and another insulating substrate is placed with the side where the circuit conductor 31 faces the outside facing upward. By laminating 1B, a double-sided circuit board can be formed.

According to this reference example , the insulating substrate 1A,
By superimposing and integrating the prepreg sheet 7 between 1B, the insulating substrates 1A and 1B and the circuit conductors 31 and 32 are formed.
Can be made into a double-sided board, and the interlayer distance can be shortened by this, and when the circuit conductors 31 and 32 are connected by through holes or fasteners to form a part of an electric circuit, the inductance of the electric circuit is reduced. In addition, the size of the circuit board can be reduced.

Reference Example 5. FIG. 9 is a sectional view showing a circuit board according to a reference example 5 of the present invention. In the figure, 3B and 3C are circuit conductors, and 12 is a hole 13 penetrating each circuit conductor 3B portion of the insulating substrates 1A and 1B.
It is a fastener for a large current (100 A to 500 A) for caulking, which is attached to a normal printed wiring board through hole. Two caulking fasteners passing through the insulating substrate 1B are connected by the circuit conductor 3C.

Also here, in the pattern-shaped punching groove 9 of the circuit conductor 3B formed on the insulating substrates 1A and 1B,
A circuit conductor 3B having a thickness and a shape similar to the depth of the punched groove 9 is inserted, the insulating substrates 1A and 1B in which the circuit conductor 3B is inserted are laminated on the prepreg sheet 7, and then these The insulating substrates 1A, 1B and the prepreg sheet 7 are heated and pressed to embed the circuit conductors 3B in the insulating substrates 1A, 1B to form the single-sided circuit boards Q, respectively.

By caulking the fasteners 12 to the circuit boards 1A and 1B and connecting the fasteners 12 to each other, a large current can be passed from the insulating board 1A side to the insulating board 1B side or vice versa. it can.

Here, the insulating substrate 1A and the insulating substrate 1B are fixed via the fasteners 12 by a method such as screwing.

According to the method for manufacturing a circuit board of this reference example, a plurality of insulating boards 1A and 1B are arranged and fixed in the same direction at regular intervals, and the necessary circuit conductors are connected by the fasteners 12, so that heat dissipation is improved. Excellent, the single-sided circuit boards Q are easily disassembled independently of each other, and are easy to assemble.

Reference Example 6. FIG. 10 is a sectional view showing a circuit board according to Reference Example 6 of the present invention. In the figure, 11 is an insulating film, and 15 and 1.
Reference numeral 5 denotes a gap between the insulating film 11 and the upper and lower insulating substrates. The double-sided circuit board R composed of the insulating boards 1A and 1B was the same as that obtained in Reference Example 4 . In this reference example , an insulating film 11 having a high insulating property is positioned between a plurality of double-sided circuit boards R and they are combined with a certain gap 15 therebetween.

First, the punching grooves 1c, 1 of the pattern shape of the circuit conductors 31, 32 formed on the insulating substrates 1A, 1B.
The circuit conductors 31 and 32 having the same thickness and shape as the depths of the punched grooves 1c and 1d are inserted in d.

The insulating substrates 1A and 1B in which the circuit conductors 31 and 32 are inserted are laminated so as to sandwich the prepreg sheet 7, and the insulating substrates 1A and 1B and the prepreg sheet 7 are heated and pressed. The circuit conductors 31 and 32 are embedded in the insulating substrates 1A and 1B.

That is, the prepreg sheet 7 is laid on the insulating substrate 1A with the side where the circuit conductor 32 faces the outside facing downward, and another insulating substrate is placed on this side with the side where the circuit conductor 31 faces the outside facing upward. By laminating 1B, a double-sided circuit board can be formed.

[0069] Then, in this way to form a double-sided circuit board R which is formed by, arranged at a constant gap these plurality respectively through the insulating film 11, the between circuit conductors 31 and 32 which require reference By connecting with the same fasteners (not shown) as in Example 5 , it is possible to form a circuit board with good heat dissipation that is easy to assemble and assemble independently. Further, since the insulating film 11 is arranged between the insulating substrates 1A and 1B, the insulating property between layers becomes excellent.

[0070]

As described above, according to the first aspect of the invention, the pattern shape of the circuit conductor is punched out from the insulating substrate.
A groove is formed and a circuit conductor thinner than this depth is formed in the punching groove.
The releasability of the body and its depth minus the thickness of the circuit conductor
After inserting a good dummy board, prepreg the insulating board
Laminate on a sheet and heat and pressurize these laminates.
By embedding the circuit conductor in the insulating substrate,
Since it was configured to remove the dummy plate above,
The circuitry conductive portions to the same thickness as the insulating substrate by using a chromatography plate
By doing so, heating and pressurizing the insulating substrate and the prepreg sheet
Enable and remove the dummy plate after heating and pressing
This ensures a sufficient creepage distance between circuit conductors in the insulating substrate.
It has the effect of ensuring the insulation property.

According to the second aspect of the present invention, a punching groove having a pattern shape of the circuit conductor is formed in the insulating substrate, and a circuit conductor thicker than the depth thereof is inserted into the punching groove. After covering the protruding part with a punching groove of a dummy plate having a good releasability equal to the thickness of this part, laminate a prepreg sheet on the surface of the insulating substrate opposite to the covered side, and Since a part of the circuit conductor is embedded in the insulating substrate and the dummy plate is removed by heating and pressing together, the part of the circuit conductor can be exposed on the insulating substrate. There is an effect that can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a circuit board according to Comparative Example 1 of the present invention.

FIG. 2 is a plan view showing an insulating substrate in which a punching groove of the large current circuit in FIG. 1 is formed.

FIG. 3 is a plan view showing a situation in which a circuit conductor for large current is inserted into a punching groove in FIG.

FIG. 4 is a sectional view showing a circuit board according to Comparative Example 2 of the present invention.

FIG. 5 is a process drawing showing the method of manufacturing the circuit board according to the first embodiment of the present invention.

FIG. 6 is a process drawing showing a method of manufacturing a circuit board according to a second embodiment of the present invention.

FIG. 7 is a process drawing showing a method of manufacturing a circuit board according to a comparative example 3 of the present invention.

FIG. 8 is a sectional view showing a circuit board according to a comparative example 4 of the present invention.

FIG. 9 is a sectional view showing a circuit board according to Comparative Example 5 of the present invention.

FIG. 10 is a sectional view showing a circuit board according to Comparative Example 6 of the present invention.

FIG. 11 is a plan view showing a conventional circuit board partially broken away.

12 is a cross-sectional view showing the circuit board in FIG.

FIG. 13 is a cross-sectional view showing another conventional circuit board.

[Explanation of symbols]

1A-1D insulating substrate, 3, 3A, 3B, 3C, 31,
32 circuit conductors, 7 prepreg sheets, 9, 10a
Punching groove, 10, 10A dummy plate, 11 insulating film, 12 fastener, 15 gap, P, Q single-sided circuit board, R double-sided circuit board.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshifumi Kimura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (56) Reference JP-A-6-291434 (JP, A) JP-A-5 -136579 (JP, A) JP-A-6-169147 (JP, A) JP-A-3-21095 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 1/02 H05K 3/20

Claims (2)

(57) [Claims] 1. A pattern conductor punching groove is formed on an insulating substrate, a circuit conductor thinner than the depth of the punching groove is formed in the punching groove, and the thickness of the circuit conductor is reduced from the depth of the punching groove. After inserting a good dummy plate, the insulating substrate is laminated on a prepreg sheet, and the circuit conductor is embedded in the insulating substrate by heating and pressing them together, and then the dummy plate is removed from the punching groove. Circuit board manufacturing method. 2. A punching groove having a pattern shape of a circuit conductor is formed on an insulating substrate, a circuit conductor having a thickness larger than the depth of the punching groove is inserted into the punching groove, and the circuit conductor is formed at a portion protruding from the insulating substrate. After covering with a punching groove of a dummy plate having a good releasability equal to the thickness of the part, by laminating a prepreg sheet on the surface of the insulating substrate on the side opposite to this covering side and heating and pressing them together, A method of manufacturing a circuit board, wherein a part of the circuit conductor is embedded in the insulating substrate, and then the dummy plate is removed from the circuit conductor.