JPH08316592A - Circuit board and production thereof - Google Patents

Abstract

PURPOSE: To obtain a circuit board where the board body is made of a metallic material, and a production method thereof, in which the electric characteristics, the reliability of joint and, the thermal characteristics are enhanced. CONSTITUTION: The circuit board 1 comprises a metal board body 2 provided with recesses at predetermined positions including positions for forming a wiring pattern 5, the wiring pattern 5 arranged in the recesses 3 provided in the metal board body 2, and a member 4 for electrically insulating the wiring pattern 5 from the metal board body 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board and a method of manufacturing the same, and more particularly to a circuit board having a board body formed of a metal material and a method of manufacturing the same. In general, a circuit board on which electronic equipment such as a semiconductor device is arranged has a wiring pattern formed on the board body, and the leads of the electronic equipment are connected to the electrode part formed as a part of the wiring pattern. It is configured to be.

Further, with the recent miniaturization and high density of electronic equipment, the lead pitch tends to be narrowed, and therefore the pitch of the electrode portions formed on the circuit board also tends to be narrowed. Therefore, there is a demand for a circuit board that can maintain high reliability in connection with an electronic device even if the circuit board is miniaturized and densified as described above.

[0003]

2. Description of the Related Art Conventionally, a circuit board used for arranging electronic equipment such as a semiconductor device has a surface area of 18 .mu.m.
It has a structure in which a wiring pattern is formed by applying a copper foil having a thickness of 70 μm and then performing etching, and this is used as a single substrate or as a laminated substrate obtained by laminating a plurality of sheets.

On the other hand, as a method of mounting an electronic device such as a semiconductor device (hereinafter, a semiconductor device will be described as an example) on the circuit board, the following two methods are generally performed. . One of them is a case where a lead insertion package is used as a package of a semiconductor device. In a semiconductor device adopting this lead insertion package, a through hole for lead insertion is previously formed on the circuit board,
In this method, the leads of the semiconductor device are inserted and soldered. The other method is a method of using a surface mount type package as a semiconductor device, in which an electrode pattern for mounting connection is previously formed on the upper surface of a circuit board, and a lead of the semiconductor device is soldered to this. .

In the former method of mounting a semiconductor device adopting a lead insertion package, it is necessary to form a through hole having a predetermined size in a circuit board, so that a semiconductor device having a large number of leads is mounted at high density. Therefore, the adoption of this mounting method tends to decrease in recent years. On the other hand, the surface mounting method of mounting a semiconductor device on the surface of a circuit board has been widely used in recent years because high-density mounting can be realized.

[0006]

In the surface mounting method described above, the number of leads of the semiconductor device is increased along with the recent increase in mounting density, and the leads are made smaller and thinner. For this reason, the bonding strength per lead tends to weaken, and the lateral direction (shear direction) that is most involved in lead destruction
It is necessary to configure the circuit board so that no stress is applied to the stress of. The stress in the shearing direction is mainly caused by the difference in thermal expansion between the lead and the circuit board.

However, since the conventional circuit board uses paper phenol, glass epoxy or the like as the board body as described above, there is a large difference in thermal expansion between the lead, which is a metal material, and the board body, so that stress in the shearing direction is generated. Then, there is a problem that the lead is easily broken.

Further, in the surface mounting method, heat generated from the semiconductor device is likely to be trapped on the circuit board due to high density mounting. Therefore, it is necessary to efficiently dissipate the heat generated from the semiconductor device. However, the circuit board using paper phenol, glass epoxy or the like as the main body of the circuit has poor thermal conductivity as in the past, and therefore the air cooling method is used to force the circuit board. Cooling to be done.

However, with the method of forcibly cooling by the air cooling method as described above, it is difficult to satisfactorily perform cooling processing on each of a large number of semiconductor devices mounted in high density, and the heat diffusivity is high. Since it is also defective, there is a problem that an efficient cooling process cannot be performed.

Further, due to the increase in signal speed accompanying the increase in speed of semiconductor devices in recent years, reduction of noise intruding from a circuit board has become an important issue. Generally, in a conventional circuit board, a so-called solid pattern having a power supply potential or a ground potential is formed on the circuit board in order to suppress potential variation caused by various noises on the signal.

However, it is necessary to form a wide solid pattern in order to surely prevent noise from entering by using the solid pattern, but there is a space limitation in the circuit board for high-density mounting as described above. Yes Solid pattern cannot be formed widely. Therefore, the method of forming a solid pattern on the upper surface of the substrate cannot effectively prevent the intrusion of noise. In addition, the method of forming a solid pattern on the upper surface of the substrate has a problem in that it cannot be expected to be effective against electromagnetic noise emitted from the outside of the semiconductor device.

The present invention has been made in view of the above points, and an object of the present invention is to provide a circuit board and a manufacturing method thereof capable of improving the electrical characteristics, the reliability of the joint portion and the thermal characteristics.

[0013]

In order to solve the above problems, the present invention is characterized by taking the following means. According to the first aspect of the present invention, the circuit board includes a metal substrate main body having a recess formed at a predetermined position including a wiring pattern forming position, and a wiring pattern arranged in the recess formed in the metal substrate main body. It is characterized by comprising an insulating member that electrically insulates the wiring pattern and the metal substrate body.

The invention according to claim 2 is characterized in that, in the circuit board according to claim 1, the recesses and the wiring patterns are provided on both upper and lower surfaces of the metal substrate body. .

Further, in the invention according to claim 3, in the circuit board according to claim 2, the metal board body is penetrated in an insulated state, and the upper surface and the lower surface of the metal board body are provided. It is characterized in that a through connection member for electrically connecting is provided.

According to a fourth aspect of the present invention, in the circuit board according to any one of the first to third aspects, the metal substrate main body is provided with an electrode portion exposed from the insulating member, It is characterized in that the substrate body is used as wiring.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a circuit board, comprising a step of forming a metal substrate main body by forming a concave portion at a predetermined position of a metal base material, and at least the concave portion. A first insulating member arranging step of arranging a first insulating member on the wiring, and wiring for forming a wiring pattern in a predetermined pattern on the insulating member arranged in the first insulating member arranging step It is characterized by including a pattern forming step and a second insulating member disposing step of disposing a second insulating member so as to cover at least the wiring pattern formed in the wiring pattern forming step. It is a thing.

Further, in the invention according to claim 6, in the method for manufacturing a circuit board according to claim 5, in the step of disposing the second insulating member, a connection hole is formed so that a predetermined portion of the wiring pattern is exposed. It is characterized by forming.

[0019]

The above-mentioned means operate as follows. According to the first aspect of the invention, the wiring pattern is positioned in the recess formed in the metal substrate body while being electrically insulated from the metal substrate body by the insulating member. Therefore, most of the outside of the wiring pattern is surrounded by the metal substrate body. Since this metal substrate body functions as a shield material, it is possible to reduce crosstalk between the wiring patterns arranged in the adjacent recesses and to shield the wiring pattern from the external electromagnetic field. You can

Further, since the metal substrate body is made of metal similarly to the wiring pattern, it is possible to make the thermal expansion coefficients of the metal substrate body and the wiring pattern close to each other, and even if heat treatment is performed at the time of mounting electronic parts. It is possible to prevent the wiring pattern from being damaged due to the difference in thermal expansion.

When a metal lead is provided in the electronic component mounted on the circuit board, it is easy to match the difference in thermal expansion between the metal lead and the circuit board. The reliability can be improved.
In addition, the circuit board has a high heat dissipation due to its high metal content, so that even if electronic components that generate heat are mounted, the generated heat can be efficiently dissipated through the circuit board, and thermal reliability is also improved. Can be made.

According to the second aspect of the present invention, the recesses and the wiring patterns are provided on the upper and lower surfaces of the metal substrate body respectively, so that electronic components can be provided on the upper and lower surfaces of the circuit board. It is possible to improve the mounting density of electronic components. According to the invention of claim 3,
By providing the through connection member that penetrates the metal substrate body and electrically connects the upper surface and the lower surface of the metal substrate body, the upper surface and the lower surface of the metal substrate body can be electrically connected with a simple configuration. .

According to the invention of claim 4, since the metal substrate main body is used as the wiring, the number of wiring patterns can be reduced, and since the metal substrate main body has a small electric resistance, it can be grounded. Alternatively, the electrical characteristics can be improved by using it as a power supply wiring.

According to the method of the invention described in claims 5 and 6, it is possible to easily form the circuit board according to claims 1 to 4 described above in a small number of steps.

[0025]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a sectional view of a circuit board 1 according to a first embodiment of the present invention, and FIG. 2 is a perspective view showing a state in which an electronic component 7 is mounted on the circuit board 1 according to the first embodiment of the present invention. is there.

As shown in FIG. 1, the circuit board 1 is roughly composed of a metal board body 2, an insulating member 4, a wiring pattern 5 and the like. The metal substrate body 2 is made of copper,
It is formed of a lead material or the like such as copper alloy, aluminum, or 42 alloy, and as the material thereof, a material having electrical conductivity and good thermal conductivity is selected.
A plurality of recesses 3 are formed at predetermined positions on the top of the metal substrate body 2. The formation position of the concave portion 3 is selected as the arrangement position of the wiring pattern 5 described later.

The insulating member 4 is an insulating resin such as epoxy, and is arranged so as to cover the entire upper surface of the metal substrate body 2. Therefore, the insulating member 4 is also filled inside the recess 3 formed in the metal substrate body 2. The wiring pattern 5 is generally used as a wiring material for a circuit board, such as copper, and is formed in a predetermined pattern based on the layout of electronic components mounted on the circuit board 1. As described above, the recess 3 formed in the metal substrate body 2 is configured so as to correspond to the formation position of the wiring pattern 5. Therefore, the wiring pattern 5 is located inside the recess 3.

The wiring pattern 5 is embedded in the insulating member 4, so that the wiring pattern 5 is electrically insulated from the metal substrate body 2. Furthermore, the electronic component 7 of the wiring pattern 5 (semiconductor device)
A connection hole 6 is formed in the insulating member 4 at a portion electrically connected to the wiring pattern 5 through the connection hole 6.
And the electronic component 7 can be electrically connected.

Specifically, as shown in FIG. 2, the formation position of the connection hole 6 is selected so as to correspond to the electrode portion 8 formed on the electronic component 7, and the connection hole 6 is formed at the formation position by soldering. The wiring pattern 5 and the electrode portion 8 are connected by disposing 9. As a result, the electronic component 7 is surface-mounted on the circuit board 1.

As described above, in the circuit board 1 according to the present embodiment, the wiring pattern 5 is electrically insulated from the metal board body 2 by the insulating member 4, and the metal board body 2 is maintained.
The structure is located inside the concave portion 3 formed in. Therefore, most of the wiring pattern 5 is surrounded by the metal substrate body 2.

On the other hand, since the metal substrate body 2 is made of a conductive material, the metal substrate body 2 functions as a shield material. Therefore, it is possible to reduce the crosstalk between the wiring patterns 5 arranged in the adjacent recesses 3 and to shield the wiring pattern 5 from an external electromagnetic field. As a result, even if the electronic component 7 (semiconductor device) having the increased speed is mounted, interference does not occur between the wiring patterns 5 and noise can be prevented from entering from an external electromagnetic field. The electrical characteristics can be improved.

Since the metal substrate body 2 is made of metal similarly to the wiring pattern 5, the metal substrate body 2 is
It is possible to approximate the coefficient of thermal expansion between the wiring pattern 5 and the wiring pattern 5. Therefore, even if the electronic component 7 is heat-treated at the time of mounting, the wiring pattern 5 is not peeled off due to the difference in thermal expansion.

Further, since the metal substrate body 2 is made of metal similarly to the electrode portion 7 of the electronic component 7, the thermal expansion coefficients of the metal substrate body 2 and the electrode portion 7 can be approximated. Therefore, it is possible to prevent the shearing force due to the difference in thermal expansion from being generated at the joint between the circuit board 1 and the electronic component 7, and to prevent the joint from being damaged. Therefore, the reliability when the electronic component 7 is mounted can be improved.

Further, since the circuit board 1 has a high metal ratio and the metal board body 2 is made of a material having good heat conductivity, the heat dissipation of the circuit board 1 is good. Therefore, even if the heat-generating electronic components 7 are mounted at a high density, the generated heat can be efficiently radiated through the circuit board 1, and the thermal reliability can be improved.

Next, a method of manufacturing the circuit board 1 having the above structure will be described with reference to FIG. In order to manufacture the circuit board 1, first, as shown in FIG.
A flat plate-shaped base material 10 made of a material having conductivity and good heat conductivity, such as a copper alloy, aluminum, and a lead material.
To prepare. Subsequently, the base material 10 is etched or machined to form a plurality of recesses 3 at predetermined positions on the top surface of the base material 10 as shown in FIG. Form 2. Incidentally, this recess 3
The formation position of is formed so as to correspond to the arrangement position of the wiring pattern 5.

After the metal substrate body 2 is formed as described above, subsequently, as shown in FIG. 3 (C), the lower insulating member 11 is applied to the upper surface of the metal substrate body 2 in which the concave portion 3 is formed. It The lower insulating member 11 is an insulating resin such as polyimide, and is formed by a potting method or the like to have a film thickness that is approximately half that of the insulating member 4 described above.

When the lower insulating member 11 is formed on the upper surface of the metal substrate body 2 as described above, the wiring pattern 5 is subsequently formed on the lower insulating member 11 as shown in FIG.
Are formed in a predetermined pattern. The wiring pattern 5 is formed, for example, by forming a metal film such as copper on the entire upper surface of the lower insulating member 11 to be the wiring pattern 5, and then performing an etching process. When the lower insulating member 11 is coated on the upper surface of the metal substrate body 2 and unevenness is generated in the lower insulating member 11, the surface of the lower insulating member 11 is flattened before the formation of the wiring pattern 5. A forming process may be performed.

After the wiring pattern 5 is formed on the lower insulating member 11 as described above, subsequently, as shown in FIG. 3E, the upper insulating member is applied to the upper surface of the metal substrate body 2. Thus, the insulating member 4 is formed. At this time, a connection hole 6 is formed above the wiring pattern 5 electrically connected to the electronic component 7. As a result, the wiring pattern 5 is embedded in the insulating member 4, and is electrically insulated from the metal substrate body 2. In this state, most of the wiring pattern 5 is surrounded by the metal substrate body 2
Is surrounded by the insulating member 4.

As described above, the circuit board 1 according to this embodiment
According to the manufacturing method (1), the circuit board 1 having the various effects described above can be manufactured in a simple and small number of steps. Subsequently, a second embodiment of the present invention will be described. FIG. 4 shows a circuit board 20 which is a second embodiment of the present invention. In FIG. 4, components corresponding to those of the circuit board 1 according to the first embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The circuit board 1 according to the first embodiment described above is
The wiring pattern 5 was formed only on the upper surface of the metal substrate body 2. The circuit board 20 according to the present embodiment has wiring patterns 2 on both the upper surface and the lower surface of the metal substrate body 2.
2 and 23 are formed.

Therefore, the circuit board 20 according to the present embodiment.
The upper recess 24 is formed on the upper surface of the metal substrate body 2. The upper wiring pattern 22 is formed via the insulating member 4 at a position corresponding to the position where the upper recess 24 is formed. Further, a lower recess 25 is formed on the lower surface of the metal substrate body 2, and a lower wiring pattern 23 is formed at a position corresponding to the position where the lower recess 25 is formed, with an insulating member 4 interposed therebetween.

Further, the circuit board 20 according to this embodiment has wiring patterns 22, respectively on the upper surface and the lower surface of the metal substrate body 2.
By forming 23, the electronic component 7 is also mounted on both the upper surface and the lower surface of the metal substrate body 2. With this configuration, it becomes necessary to electrically connect the upper surface side and the lower surface side of the metal substrate body 2.

Therefore, in the circuit board 20 according to this embodiment, the through holes 21 (penetrating connection members) for electrically connecting the upper surface side and the lower surface side of the metal substrate body 2 are formed. The through hole 21 is formed by forming a through hole in the metal substrate body 2, forming an insulating film on the inner wall of the through hole, and disposing a conductive metal powder or a conductive metal column.

As in this embodiment, the wiring patterns 22 and 23 are formed on the upper surface and the lower surface of the metal substrate body 2 respectively, and the upper surface and the lower surface side of the metal substrate body 2 are electrically connected by the through holes 21. As a result, the electronic components 7 can be mounted on the upper surface and the lower surface of the circuit board 20, respectively, and the mounting density of the electronic components 7 can be further improved as compared with the circuit board 1 according to the first embodiment.

Next, a third embodiment of the present invention will be described. FIG. 5 shows a circuit board 30 according to a third embodiment of the present invention.
Is shown. In FIG. 5, components corresponding to those of the circuit boards 1 and 20 according to the first and second embodiments shown in FIGS. 1 to 4 are designated by the same reference numerals and the description thereof is omitted.

The circuit board 30 according to this embodiment is characterized in that the metal substrate body 2 is used as a wiring. In this embodiment, the metal substrate body 2 is used as a ground (ground) wiring. An example is shown. By using the metal substrate body 2 as wiring as described above, it is necessary to electrically connect the metal substrate body 2 to the electronic components 7 and the like, and therefore, a part of the metal substrate body 2 is exposed from the insulating member 4. It is configured. Specifically, the upper ground electrode 32 is formed on the upper surface side of the metal substrate body 2, and the lower ground electrode 33 is formed on the lower surface side. Further, in FIG. 4, 31 is a through hole, and in this embodiment, the through hole 31 is the wiring pattern 2.
2 and 23 are directly connected to each other.

As described above, by using the metal substrate body 2 as the wiring, it is possible to reduce the number of wiring patterns 22 and 23 to be formed, and to have flexibility in designing the positions where the wiring patterns 22 and 23 are formed. Can be made. Further, since the metal substrate body 2 has a small electric resistance, by using this as a ground line, the wiring pattern 22,
The shielding effect of 23 can be further improved.

Further, although the metal substrate body 2 is used as the ground wiring in this embodiment, the voltage drop can be reduced by using the metal substrate body 2 as the power source wiring, which also improves the electrical characteristics. You can In each of the above-described embodiments, the circuit board 20 is configured as a single circuit board composed of only one metal board body 2. However, the metal board body having the wiring patterns 5, 22, 23 is formed. It is also possible to use a laminated structure substrate having a structure in which a plurality of 2 are laminated.

In the above-described embodiment, the insulating member 4 is made of an insulating material such as a resin. However, the material of the insulating member 4 is not limited to resin, and may be ceramic. A structure using another insulating material may be used.

[0050]

Each of the above means operates as follows.
According to the first aspect of the present invention, it is possible to reduce the crosstalk between the wiring patterns arranged in the adjacent recesses and to shield the wiring patterns from an external electromagnetic field.

Further, since the metal substrate body is made of metal similarly to the wiring pattern, the coefficient of thermal expansion between the metal substrate body and the wiring pattern can be made close to each other, and even if heat treatment is performed at the time of mounting electronic parts, etc. The wiring pattern is not peeled off due to the difference in thermal expansion.

When a metal lead is provided in the electronic component mounted on the circuit board, it is easy to match the difference in thermal expansion between the metal lead and the circuit board. The reliability can be improved.
In addition, the circuit board has a high heat dissipation due to its high metal content, so that even if electronic components that generate heat are mounted, the generated heat can be efficiently dissipated through the circuit board, and thermal reliability is also improved. Can be made.

According to the second aspect of the invention, the recesses and the wiring patterns are provided on the upper and lower surfaces of the metal substrate body, respectively, so that electronic components can be provided on the upper and lower surfaces of the circuit board. It is possible to improve the mounting density of electronic components. According to the invention of claim 3,
By providing the through connection member that penetrates the metal substrate body and electrically connects the surface and the lower surface of the metal substrate body, the electrical connection between the surface and the lower surface of the metal substrate body can be performed with a simple configuration. .

According to the invention of claim 4, since the metal substrate main body is used as the wiring, the number of wiring patterns can be reduced, and the metal substrate main body has a small electric resistance. Alternatively, the electrical characteristics can be improved by using it as a power supply wiring.

According to the method of the invention described in claims 5 and 6, it is possible to easily form the circuit board according to claims 1 to 4 described above in a small number of steps.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a circuit board that is a first embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which electronic components are mounted on the circuit board according to the first embodiment of the present invention.

FIG. 3 is a drawing for explaining the manufacturing method of the circuit board according to the embodiment of the present invention.

FIG. 4 is a sectional view showing a circuit board according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a circuit board according to a third embodiment of the present invention.

[Explanation of symbols]

 1, 20, 30 Circuit board 2 Metal board body 3 Recess 4 Insulation member 5 Wiring pattern 6 Connection hole 10 Base material 21, 31 Through hole 22 Upper wiring pattern 23 Lower wiring pattern 24 Upper recess 25 Lower recess 32 Upper ground electrode 33 Lower Ground electrode

Claims (6)

[Claims] 1. A metal substrate body having a recess formed at a predetermined position including a wiring pattern forming position, a wiring pattern arranged in the recess formed in the metal substrate body, the wiring pattern and the metal. A circuit board comprising an insulating member electrically insulating the board body. 2. The circuit board according to claim 1, wherein the concave portion and the wiring pattern are provided on both upper and lower surfaces of the metal substrate body, respectively. 3. The circuit board according to claim 2, wherein the circuit board is configured to penetrate the metal board main body in an insulated state, and electrically penetrates the upper surface and the lower surface of the metal board main body. A circuit board provided with. 4. The circuit board according to claim 1, wherein an electrode portion having a structure exposed from the insulating member is formed on the metal substrate body, and the metal substrate body is used as a wiring. A circuit board characterized by the above. 5. A metal substrate main body forming step of forming a metal substrate main body by forming a concave portion at a predetermined position of a metal base material, and a first insulating member for disposing a first insulating member in at least the concave portion. An arranging step, a wiring pattern forming step of forming a wiring pattern in a predetermined pattern on the insulating member arranged in the first insulating member arranging step, and formed at least in the wiring pattern forming step A second insulating member disposing step of disposing a second insulating member so as to cover the wiring pattern. 6. The circuit board manufacturing method according to claim 5, wherein in the second insulating member disposing step, a connection hole is formed so that a predetermined portion of the wiring pattern is exposed. Manufacturing method.