JPH06326427A - Printed wiring board - Google Patents

Abstract

PURPOSE:To obtain a printed wiring board consisting of a metal plate coated with an insulating resin film and having a recessed part on the upper surface of the metal plate where an electronic part, having large amount of heat generated, is mounted, by connecting a heterogenous metal part, with the thermal conductivity higher than the thermal conductivity of the metal plate, to the above-mentioned recessed part. CONSTITUTION:The upper surface of the heat-generating part, corresponding to an electronic part 4a having a large heat value, of a metal plate 3, is shaved and a recessed part is formed, and a heterogenous metal plate of the heat conductivity higher than that of the metal plate 3 is connected to the recessed part. When the heat value of the electronic part 4a is greatly higher than the electronic part 4b, the heat generated by the electronic part 4a is transmitted to a cooling part 5 through an insulating resin part 2, and a heterogenous metal part 6a. Also, the heat generated by the electronic part 4a is transmitted to the metal plate 3 from the heterogenous metal part 6a, then to a cooling part and discharged to outside. Material such as aluminum and the like is used for the metal plate 3, and copper is used for the heterogenous metal part 6 having excellent heat conductivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board, and more particularly to a printed wiring board on which electronic parts requiring heat radiation are mounted.

[0002]

2. Description of the Related Art FIG. 15 shows, for example, JP-A-56-1127.
It is sectional drawing which shows the conventional printed wiring board shown by the 97 publication. In FIG. 15, reference numeral 1 is a printed wiring board, 2 is an insulating resin portion of the printed wiring board, 3 is a metal plate coated with the insulating resin portion 2 for transmitting heat, 4a and 4b are electronic components mounted on the printed wiring board 1. Reference numeral 5 denotes a cooling unit that is in contact with the metal plate 3 and radiates the heat of the metal plate 3.

Next, the function of heat dissipation in the conventional printed circuit board will be described. A large amount of heat is generated from the electronic components 4a and 4b mounted on the printed wiring board 1 during the operation of this circuit. The generated heat is transferred to the metal plate 3 via the insulating resin part 2, and further to the cooling part 5 via the metal plate 3. Then, the heat is released from the cooling unit 5. At this time, the metal plate 3 that conducts heat from the electronic components of the printed wiring board 1 is screwed to the cooling unit 5 or the like,
Since it is more mechanically fixed, contact thermal resistance is low.

[0004]

Since the conventional printed wiring board is constructed as described above, the electronic component 4a and the electronic component 4b often have a difference in heat generation amount or thermal weakness. For example, when the heat generation amount of the electronic component 4a is larger than the heat generation amount of the electronic component 4a, the heat generation amount of the electronic component 4a is taken into consideration, and the electronic component 4a having a large heat generation amount is arranged at an advantageous position on the printed wiring board. The thickness of the metal plate 3 is increased so that heat can be easily dissipated. As described above, since the entire thickness of the metal plate 3 is matched with the electronic component 4a having the larger heat generation, the thickness of the metal plate 3 for radiating heat from the electronic component 4b becomes too thick, resulting in a volume increase. However, there is a problem that the device becomes large and heavy.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a printed wiring board which is small in size, light in weight and excellent in heat radiation performance.

[0006]

As shown in FIG. 1, a printed wiring board according to the first aspect of the present invention has a recess in the upper surface of a metal plate 3 which is a range corresponding to an electronic component 4a having a large heat generation amount. It was shaved, and a dissimilar metal portion 6a having a thermal conductivity higher than that of the metal plate was joined to the recess. In the printed wiring board according to the second invention, as shown in FIG. 6, the upper surface and the lower surface of the metal plate 3, which is a range portion corresponding to the electronic component 4a having a large heat generation amount, are cut into concave portions, and the concave portions are formed in the respective concave portions. The dissimilar metal portions 6b having a thermal conductivity higher than that of the metal plate were joined. As shown in FIG. 7, the printed wiring board according to the third invention has a higher thermal conductivity than that of the metal plate 3 on the upper surface of the metal plate 3 which is a range corresponding to the electronic component 4a having a large heat generation amount. The dissimilar metal parts 6c having thermal conductivity were joined. The printed wiring board according to the fourth invention is shown in FIG.
As shown by, the entire metal plate 3 in a range corresponding to the electronic component 4a having a large heat generation is cut, and the cut portion has a dissimilar metal portion 6 having a higher thermal conductivity than that of the metal plate.
Joined d. The printed wiring board according to the fifth aspect of the present invention, as shown in FIG.
A heat pipe portion 12 made of metal or the like having a hollow inside or a metal having a thermal conductivity higher than that of the metal plate 3 is provided in the metal plate 3 in the range corresponding to.

[0007]

In the printed wiring board according to the first aspect of the present invention, the upper surface of the metal plate 3, which is a range corresponding to the electronic component 4a having a large heat generation amount, is cut into a recess. Then, the dissimilar metal portion 6 having a thermal conductivity higher than that of the metal plate is provided in the recess.
a is joined by an adhesive sheet or the like. In the printed wiring board according to the second aspect of the present invention, first, the upper surface and the lower surface of the metal plate 3, which is a range corresponding to the electronic component 4a having a large heat generation amount, are cut into recesses. Then, a dissimilar metal portion 6b having a thermal conductivity higher than that of the metal plate is joined to each recess by an adhesive sheet or the like. In the printed wiring board according to the third aspect of the present invention, a dissimilar metal having a thermal conductivity higher than that of the metal plate is first formed on the upper surface of the metal plate 3 which is a range corresponding to the electronic component 4a having a large heat generation amount. The portion 6c is joined by an adhesive sheet or the like. In the printed wiring board according to the fourth aspect of the present invention, first, the entire metal plate 3, which is a range corresponding to the electronic component 4a having a large heat generation amount, is cut off. A dissimilar metal portion 6d having a thermal conductivity higher than that of the metal plate is joined to the cut portion by an adhesive sheet or the like. In the printed wiring board according to the fifth aspect of the present invention, first, the inside of the metal plate 3, which is a range corresponding to the electronic component 4a having a large heat generation amount, is hollow or has a thermal conductivity higher than that of the metal plate. The heat pipe section 12 made of metal or the like is joined by an adhesive sheet or the like.

[0008]

EXAMPLES Example 1. An embodiment of the present invention will be described below. 1 is a sectional view of a printed wiring board according to Embodiment 1 of the present invention. In FIG. 1, 1 is a printed wiring board, 2 is an insulating resin portion of the printed wiring board 1, 3 is a metal plate for transmitting heat, 4a and 4b are electronic components mounted on the printed wiring board 1, and 5 is a metal plate 3. A cooling unit that dissipates heat,
Reference numeral 6 denotes a dissimilar metal portion that is joined to the metal plate 3 and that transfers heat from the metal plate 3 to the cooling unit 5 and that has good heat conduction. 2 is a plan view of this printed wiring board, and FIG. 3 is a sectional view of this printed wiring board. In the printed wiring board according to the first embodiment, the upper surface of the metal plate 3 in the heat generation range corresponding to the electronic component 4a having a large heat generation amount is cut into a concave portion, and the metal plate 3 is formed in the concave portion.
The dissimilar metal portion 6 having a higher thermal conductivity than that of No. 1 is joined. By doing so, the amount of heat generated from the electronic component 4a, which generates a larger amount of heat than other electronic components, is transmitted to the cooling unit 5 via the dissimilar metal unit 6 and radiated.

Next, the heat radiation effect of this printed wiring board will be described. Generally, there are many types of electronic components mounted on a printed wiring board. Therefore, the heat generation power of these electronic components is not uniform in each component, and there is a difference in magnitude depending on the scale of integration of the electronic components and the operating speed. For example, in FIG. 1, assuming that the heat generated by the electronic component 4a is much larger than that generated by the electronic component 4b, the heat generated by the electronic component 4a is transmitted to the cooling unit 5 via the insulating resin portion 2 and the dissimilar metal portion 6a. Further, the heat generated from the electronic component 4a is also transferred from the dissimilar metal part 6a to the metal plate 3 and is transferred to the cooling part 5. Then, the heat is released from the cooling unit 5 to the outside. On the other hand, the heat generated from the electronic component 4b is transmitted to the cooling unit 5 via the insulating resin portion 2 and the metal plate 3. In the first embodiment, since the dissimilar metal portion 6 is made of a material having better heat conductivity than the metal plate 3, the dissimilar metal portion 6a has a lower thermal resistance than the metal plate 3.
The heat dissipation of the electronic component 4a, which generates a large amount of heat, is promoted, and the temperature can be lowered. Further, with respect to the electronic component 4b, since the amount of heat generated from the electronic component is relatively small, the metal plate 3 can also sufficiently radiate heat. Therefore, the required thickness of the entire metal plate 3 can be reduced according to the electronic component 4b. For example, a lightweight material such as aluminum is used for the metal plate 3, and copper is used for the dissimilar metal portion 6 having better heat conduction. However, among metallic materials such as aluminum and copper that can be used for printed wiring boards, a material having good heat conduction generally has a large specific gravity, and a material having poor heat conduction has a small specific gravity. Therefore, the weight of the printed wiring board becomes heavy if a large amount of a material having good heat conduction is used, or if the material is partially used, there is not much problem with the weight. By the way, copper has a thermal conductivity of 0.9 cal / cm sec ° C and a specific gravity of 8.
9. Aluminum has a thermal conductivity of 0.5 cal / cm
sec ° C, specific gravity = 2.7.

FIG. 4 and FIG. 5 are cross-sectional views seen from the front and side showing the step of joining the printed wiring boards. In FIGS. 4 and 5, (a) shows the metal plate 3 before processing, and (b) shows the step of cutting the metal plate 3 into a groove shape and providing the cut-out portion 7. (C) is a step of attaching an adhesive sheet 8 to the scraped portion 7, (d) is a step of joining the dissimilar metal portion 6 with the adhesive sheet 8, and (e) is used for the printed wiring board 1. The process of adhering the insulating resin part 2 is shown. Next, a procedure for manufacturing this printed wiring board will be described. First, in the metal plate 3, an electronic component 4a having a large heat generation power
The heat-generating portion is processed to reduce the required thickness ((b) of FIGS. 4 and 5). At this time, the cutting depth is preferably 30 to 70% of the thickness of the metal plate 3, and 0.5 to 1.0 m.
It is about m. Next, a dissimilar metal part 6 such as copper is formed on the scraped-off portion of the metal plate 3 for use in an ordinary manufacturing process of the printed wiring board 1 (adhesive sheet 8 (semi-cured resin-impregnated fiber sheet (generally called prepreg)). (See Fig. 4,)
5 (d)). At this time, the metal plate 3 and the dissimilar metal portion 6
In the case of joining the same metals, there are cases where they are joined by heating and pressurizing, or they are formed by plating. Next, after both metals (the metal plate 3 and the dissimilar metal portion 6) are joined, a surface treatment is performed, and a copper foil or an insulating resin used in ordinary printed wiring board production is adhered to the printed wiring board (see FIGS. 4 and 5). (E)).

Embodiment 2. In the first embodiment described above, in the printed wiring board 1, the dissimilar metal portion 6 having good heat conduction is used.
6 is provided only on the mounting surface side of the electronic component 4a, however, as shown in FIG. 6, dissimilar metal portions 6b having good heat conduction may be provided on both upper and lower surfaces of the mounting of the electronic component 4a. That is,
The upper surface and the lower surface of the metal plate 3 corresponding to the heat generation range corresponding to the electronic component 4a having a large heat generation amount are cut into recesses, and the dissimilar metal portions 6b having higher thermal conductivity than that of the metal plate 3 are provided in the recesses. To join. In this case, the heat resistance can be further reduced, the heat dissipation performance can be improved, and the material composition is vertically symmetrical in the thickness direction of the printed wiring board 1, and the occurrence of warpage or the like can be suppressed.

Embodiment 3. In Example 1 described above, in the printed wiring board, the portion of the metal plate 3 on which the dissimilar metal portion 6 is provided is once cut, and then the dissimilar metal portion 6 is joined.
Further, as shown in FIG. 8, the dissimilar metal portion 6c having good thermal conductivity may be joined in the same manner as the working method of the first embodiment without cutting. The dissimilar metal portion 6 having a higher thermal conductivity than that of the metal plate 3 is joined to the upper surface of the metal plate 3 in the heat generation range portion corresponding to the electronic component 4a having a large heat generation amount. By doing so, the processing of the printed board becomes relatively easy. However, since the insulating resin portion 2 has a slight step difference, the thickness of the dissimilar metal portion 6 is limited, which is effective for a component having a certain amount of heat generation power.

Embodiment 4. In the first embodiment described above, in the printed wiring board, the portion of the metal plate 3 on which the dissimilar metal portion 6 is provided is a composite of the metal plate 3 and the dissimilar metal portion 6 in the thickness direction. 11, the electronic component 4a
The metal from the part to the cooling part 5 may be only the dissimilar metal part 6 having good heat conduction. That is, the entire metal plate 3 in the heat generation range portion corresponding to the electronic component 4a having a large heat generation amount is cut off, and a dissimilar metal portion 6 having a thermal conductivity higher than that of the metal plate 3 is joined to the cut portion. . With this configuration, it is possible to obtain a printed wiring board with extremely high heat dissipation performance. As a processing method, as shown in FIG. 7, the metal plate 3 is externally processed into a required shape so that the dissimilar metal parts 6 are combined, and an adhesive or the like is applied between the boundary end faces of the metal plate 3 and the dissimilar metal part 6. Join so that there are no voids. That is, the metal plate 3 in the heat generation range corresponding to the electronic component 4a having a large heat generation amount.
Is cut off, and a dissimilar metal portion 6 having a thermal conductivity higher than that of the metal plate 3 is joined to the cut portion. In the printed wiring board according to the fourth embodiment, as with the printed wiring board according to the first embodiment, a normal metal can be produced in the manufacturing process of the printed wiring board having the built-in metal.

Example 5. In the above embodiment, the dissimilar metal portion 6
However, a heat pipe can be used as shown in FIGS. 12 to 14. 12 is a plan view of the printed wiring board, FIG. 13 is an enlarged plan view of the printed wiring board, and FIG. 14 is a sectional view of the printed wiring board.
In the figure, reference numeral 11 denotes a heat generation range of the target electronic component 4 a, and 12 denotes a heat pipe section within the heat generation range 11. At this time, the inside of the heat pipe portion 12 is made hollow or filled with metal or the like having high thermal conductivity. That is, in the metal plate 3 in the heat generation range corresponding to the electronic component 4a having a large heat generation amount, the heat pipe portion 12 made of metal or the like having a cavity or a heat conductivity higher than that of the metal plate 3 is provided in the metal plate 3. Set up. By doing so, the heat dissipation performance of the printed wiring board can be further improved.

[0015]

As described above, according to the first aspect of the present invention,
Since the upper surface of the metal plate in the range corresponding to the electronic component with a large amount of heat generation is cut into a recess and the dissimilar metal part having a higher thermal conductivity than that of the metal plate is joined to the recess, it is possible to print. This has the effects of improving the heat dissipation performance of the wiring board and reducing the weight of the printed wiring board. According to the second aspect of the invention, the upper surface and the lower surface of the metal plate in a range portion corresponding to the electronic component having a large heat generation amount are cut into recesses, and each recess has a thermal conductivity higher than that of the metal plate. Since the dissimilar metal parts are joined, there is an effect that the heat dissipation performance of the printed wiring board can be further improved and the occurrence of warpage of the printed wiring board can be suppressed as compared with the first invention. . According to the third invention, the dissimilar metal portion having a higher thermal conductivity than the thermal conductivity of the metal plate is bonded to the upper surface of the metal plate in the range corresponding to the electronic component having a large heat generation amount. So
The relatively simple processing has the effects of improving the heat dissipation performance of the printed wiring board and reducing the weight of the printed wiring board. According to the fourth aspect of the present invention, the entire metal plate in the range corresponding to the electronic component having a large amount of heat generation is cut off, and a dissimilar metal part having a thermal conductivity higher than that of the metal plate is cut in the cut part. Since they are joined together, the heat dissipation performance of the printed wiring board can be improved and the weight of the printed wiring board can be reduced. According to the fifth invention, in the metal plate in the range corresponding to the electronic component having a large calorific value, the heat pipe part made of a metal or the like having a cavity or a heat conductivity higher than that of the metal plate. Since the heat dissipation performance of the printed wiring board is further improved, the weight of the printed wiring board can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a printed wiring board according to a first embodiment of the present invention.

FIG. 2 is a plan view of the printed wiring board according to Embodiment 1 of the present invention.

FIG. 3 is a sectional view of a printed wiring board according to Embodiment 1 of the present invention.

FIG. 4 is a process diagram of joining the printed wiring boards according to the first embodiment of the present invention.

FIG. 5 is a process diagram of joining the printed wiring boards according to the first embodiment of the present invention.

FIG. 6 is a sectional view of a printed wiring board according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view of a printed wiring board according to Embodiment 3 of the present invention.

FIG. 8 is a vertical sectional view of a printed wiring board according to Embodiment 3 of the present invention.

FIG. 9 is a plan view of a printed wiring board according to Embodiment 4 of the present invention.

FIG. 10 is a sectional view of a printed wiring board according to Embodiment 4 of the present invention.

FIG. 11 is a sectional view of a printed wiring board according to Embodiment 4 of the present invention.

FIG. 12 is a plan view of a printed wiring board according to Embodiment 5 of the present invention.

FIG. 13 is an enlarged plan view of a printed wiring board according to Embodiment 5 of the present invention.

FIG. 14 is a sectional view of a printed wiring board according to Embodiment 5 of the present invention.

FIG. 15 is a cross-sectional view of a conventional printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Insulating resin part 3 Metal plate 4a, 4b Electronic component 5 Cooling part 6a-6d Dissimilar metal part 12 Heat pipe part

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[Procedure amendment]

[Submission date] August 20, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

Since the conventional printed wiring board is constructed as described above, the electronic component 4a and the electronic component 4b often have a difference in heat generation amount or thermal weakness. , for example when the heat of the electronic component 4a is larger than the heating value of the electronic component 4 b, with taking into consideration the heat dissipation of electronic components 4a, to place the large electronic components 4a excessive heat strategic locations of the printed circuit board The thickness of the metal plate 3 is made thick so as to easily dissipate heat. As described above, since the entire thickness of the metal plate 3 is matched with the electronic component 4a having the larger heat generation, the thickness of the metal plate 3 for radiating heat from the electronic component 4b becomes too thick, resulting in a volume increase. However, there is a problem that the device becomes large and heavy.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

FIG. 4 and FIG. 5 are cross-sectional views seen from the front and side showing the step of joining the printed wiring boards. In FIGS. 4 and 5, (a) shows the metal plate 3 before processing, and (b) shows the step of cutting the metal plate 3 into a groove shape and providing the cut-out portion 7. (C) a step of adhering an adhesive sheet 8 to the scraped part 7, (d) a step of joining dissimilar metal parts 6 with the adhesive sheet 8, and (e) used for the printed wiring board 1. The process of adhering the insulating resin part 2 is shown. Next, a procedure for manufacturing this printed wiring board will be described. First, in the metal plate 3, an electronic component 4a having a large heat generation power
The heat-generating portion is processed to reduce the required thickness ((b) of FIGS. 4 and 5). At this time, the cutting depth is preferably 30 to 70% of the thickness of the metal plate 3, and 0.5 to 1.0 m.
It is about m. Next, a dissimilar metal part 6 such as copper is formed on the scraped-off portion of the metal plate 3 for use in an ordinary manufacturing process of the printed wiring board 1 (adhesive sheet 8 (semi-cured resin-impregnated fiber sheet (generally called prepreg)). (See Fig. 4,)
5 (d)). At this time, the metal plate 3 and the dissimilar metal portion 6
In the case of joining the same metals, there are cases where they are joined by heating and pressurizing, or they are formed by plating. Next, after both metals (the metal plate 3 and the dissimilar metal portion 6) are joined, a surface treatment is performed, and a copper foil or an insulating resin used in ordinary printed wiring board production is adhered to the printed wiring board (see FIGS. 4 and 5). (E)).

Claims (5)

[Claims] 1. A printed wiring board comprising a metal plate having a surface coated with an insulating resin part and having a plurality of electronic components mounted thereon, wherein the upper surface of the metal plate is recessed in a range corresponding to an electronic component having a large heat generation amount. A printed wiring board, characterized in that a dissimilar metal portion having a thermal conductivity higher than that of the metal plate is joined to the recessed portion. 2. A printed wiring board comprising a metal plate having a surface coated with an insulating resin portion and mounting a plurality of electronic components, the upper surface and the lower surface of the metal plate in a range corresponding to the electronic components having a large heat generation amount. Is cut into concave portions, and dissimilar metal portions having a thermal conductivity higher than that of the metal plate are joined to the respective concave portions. 3. A printed wiring board comprising a metal plate, the surface of which is coated with an insulating resin portion, on which a plurality of electronic components are mounted, the upper surface of the metal plate being in a range corresponding to the electronic components having a large heat generation amount. A printed wiring board, characterized in that dissimilar metal parts having a higher thermal conductivity than that of the metal plate are joined together. 4. A printed wiring board comprising a metal plate having a surface coated with an insulating resin portion and having a plurality of electronic components mounted thereon, the whole metal plate being cut off in a range corresponding to an electronic component having a large heat generation amount. A printed wiring board is characterized in that a dissimilar metal portion having a higher thermal conductivity than that of the metal plate is joined to the excised portion. 5. A printed wiring board comprising a metal plate having a surface coated with an insulating resin portion and having a plurality of electronic components mounted thereon, wherein the metal plate in the range corresponding to the electronic component having a large heat generation amount is A printed wiring board is provided with a heat pipe portion made of metal or the like having a thermal conductivity higher than that of the cavity or the metal plate.