JPH0669613A - Printed wiring board - Google Patents

Abstract

PURPOSE:To acquire a printed wiring board which can surely prevent reduction of a life of an electronic component and malfunction of a circuit and can be manufactured relatively readily at a low cost. CONSTITUTION:An aluminum radiator H1 is attached to an outermost layer of a wiring board body 1. The radiator H1 and a ground pattern are electrically connected through a solid radiation pattern 2. Heat generated from a general electronic component, etc., is conducted to the radiator H1 through the ground pattern and the radiation pattern 2b. Heat is dissipated to the outside of the printed wiring board 10 from a fin 7 of the radiator H1.

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.

[0002]

2. Description of the Related Art In recent years, in printed wiring boards, which tend to be highly integrated and highly integrated, fine conductor patterns are formed on the wiring boards and a plurality of semiconductors and general electronic components are mounted in a limited space. There is a need to. In this case, as the number of mounted components increases, the amount of heat generated will inevitably increase. Therefore, in order to protect the components and avoid the malfunction of the circuit, a technique for effectively radiating heat to the outside of the wiring board is required.

As a technique for improving the heat radiation effect of the printed wiring board, the following method has been conventionally proposed. That is, there are a method of widening the line width of wiring, a method of not applying a resist on a line that generates heat, a method of arranging a metal plate inside a wiring board (so-called metal plate-based printed wiring board), and the like.

[0004]

However, the above-mentioned
In all of the conventional methods, the heat dissipation effect was insufficient, so
There are drawbacks such as shortened life of mounted electronic components and malfunction of circuits.

Further, particularly in the manufacturing process of a metal plate-based printed wiring board, it has been necessary to penetrate a thick metal plate through a hole serving as a through hole. Therefore, there are problems that the process becomes complicated and the manufacturing cost becomes high.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to reliably prevent a short life of an electronic component and a malfunction of a circuit due to a temperature rise, and at a low cost. Another object of the present invention is to provide a printed wiring board that can be manufactured relatively easily.

[0007]

In order to solve the above-mentioned problems, in the present invention, a conductive joint surface for attaching a radiator to the outer surface of the wiring board body is provided in the outermost layer of the wiring board body, and The radiator is connected to the ground layer or the ground pattern via the conductive joint surface.

[0008]

According to this structure, the heat generated from the semiconductor or the general electronic component is conducted to the radiator through the ground layer or the ground pattern and the conductive joint surface, and the heat is generated from the outer surface of the radiator to the wiring board. It is released to the outside.

[0009]

Embodiments 1 and 2 embodying the present invention will now be described in detail with reference to the drawings. [First Embodiment] FIGS. 1A and 1B show a multilayer printed wiring board (hereinafter referred to as a four-layer board) 10 of the first embodiment. The four-layer board 10 has inner layer patterns 2a and 2b.
And a wiring board body 1 having the outer layer pattern 2c, and a radiator H1 attached to the outer surface of the wiring board body 1.

The wiring board body 1 comprises an inner layer board 1a and a prepreg 1b. The inner layer pattern 2 is made of a metal such as copper on the insulating base material 3 constituting the wiring board body 1.
a and 2b are formed. The front side 2a of the inner layer pattern is a signal layer and the back side 2b is a ground layer. The prepreg 1b is thermocompression bonded to both upper and lower surfaces of the inner layer plate 1a. Also, each prepreg 1b
An outer layer pattern 2c is formed on the outer surface of the.

On the one end side (the right end side in FIG. 1A) of the prepreg 1b, a heat radiation pattern 2d as a conductive connecting surface is formed in a solid shape. Further, a plated through hole 5 is formed in the wiring board body 1. The heat radiation pattern 2d is connected to the inner ground layer 2b through the plated through hole 5. The area of this heat radiation pattern 2d is equal to the prepreg 1b.
It is preferable to secure a large size within the limit of the space. The surface of the wiring board main body 1 is solder resist 6 except for the heat radiation pattern 2d.
Is covered by.

Here, a method for manufacturing the wiring board body 1 will be briefly described. As a starting material for manufacturing the wiring board body 1, for example, a double-sided copper clad laminate is used. The double-sided copper clad laminate is first provided with a hole to be a plated through hole, and the inner surface of the hole is provided with a catalyst nucleus, and then electroless copper plating or the like is performed. Next, an etching resist is arranged at a predetermined position on the laminated board, and a part of the copper foil on the laminated board is dissolved and removed by etching. Through this process, the signal layer 2a and the ground layer 2
The inner layer plate 1a including b is formed.

Next, the inner layer plate 1a is divided into two prepregs 1b.
And then pressure is applied from the stacking direction at high temperature to thermocompress the two 1a and 1b. Thereafter, a plating resist is arranged on the outer surface of each prepreg 1b, and the outer layer pattern 2c and the heat radiation pattern 2d are formed by copper plating.
Is formed. After that, the plating resist is removed, and then the solder resist 6 is formed only on the upper surface of the conductor pattern 2a.
Is formed.

As shown in FIGS. 1 (a) and 1 (b), the radiator H1 of the first embodiment has a plurality of fins 7 arranged at equal intervals.
And a pair of mounting pieces 8. A mounting groove 8a is formed between the two mounting pieces 8. The mounting groove 8a has a width slightly wider than the thickness of the wiring board body 1. As a material for forming the radiator H1, a metal material such as aluminum having excellent thermal conductivity is used.

The heat sink H1 is attached to one of the outer surfaces of the wiring board body 1 by sandwiching the portion of the wiring board body 1 on which the heat radiation pattern 2b is formed with both mounting pieces 8. It becomes a state. In this case, the inner wall surfaces of both mounting pieces 8 and the heat radiation pattern 2d are connected by, for example, solder or the like.

According to the structure of the four-layer board 10, the heat generated from the mounted semiconductor or general electronic component is conducted to the radiator H1 via the ground pattern and the heat radiation pattern 2b. Then, the heat is radiated from the fins 7 of the radiator H1 to the outside of the four-layer plate 10, and at this time, sufficient heat radiation is achieved. Therefore, according to this configuration, it is possible to reliably prevent the shortening of the life of the electronic component and the malfunction of the circuit due to the temperature increase, which has been a conventional problem.

The four-layer board 10 does not require a thick metal plate for heat dissipation, unlike the conventional metal plate-based printed wiring board. Therefore, it is naturally unnecessary to perform a troublesome work such as providing a through hole on the metal plate. Moreover, the heat dissipation pattern 2d required in this configuration can also be formed by a general printed wiring board manufacturing process, and does not require a particularly difficult step. From the above, it is understood that the excellent four-layer board 10 can be manufactured at low cost and relatively easily.

Further, according to this structure, for example, electronic parts (large two-dot chain line shown in FIG. 1 (a)) P such as a large-sized LSI that generates a large amount of heat are concentrated and mounted on one end surface of the wiring board body 1. It is effective when it has been done. That is, if the radiator H1 is installed close to the heat source, the heat dissipation is improved. Further, when the radiator H1 is installed close to the heat source, a sufficient effect can be obtained even with a small radiator H1, resulting in space saving. [Embodiment 2] FIG. 2A and FIG.
A lamella 20 is shown. The four-layer board 20 is composed of a wiring board body 11 having inner layer patterns 12a and 12b and an outer layer pattern 12c, and a radiator H1. In this four-layer board 20, a radiator H2 is attached at a position different from that of the first embodiment, that is, on the outer surface of the wiring board 11. Also, in consideration of the difference in the mounting position, regarding the shape of the radiator H2, etc.,
It is slightly different from the first embodiment.

The wiring board body 11 comprises an inner layer board 11a and a prepreg 11b. Inner layer patterns 12a and 12b are formed of a metal such as copper on the front and back surfaces of the insulating base material 13 forming the inner layer plate 11a. In the second embodiment, the back surface side 12a of the inner layer pattern is a signal layer, and the front surface side 12b is a ground layer.
The prepreg 11b is thermocompression bonded to the upper and lower surfaces of the inner layer plate 11a. An outer layer pattern 12c is formed on the outer surface of each prepreg 11b.

A large number of plated through holes 15 are densely formed in the wiring board body 11. The outer layer land 15a of the plated through hole 15 substantially functions as a conductive connecting surface for mounting the radiator H2. These plated through holes 15 are electrically connected to the inner ground layer 12b.

The inner wall surface of the plated through hole 15 and the surface of the outer layer land 15a are covered with solder. On the other hand, the surface of the outer layer pattern 12c is covered with the solder resist 16.

As shown in FIGS. 2 (a) and 2 (b), the radiator H2 of the second embodiment has a plurality of fins 1 arranged at equal intervals.
7 and a bottom 18 for mounting. As the material for forming the radiator H2, a metal material such as aluminum having excellent thermal conductivity is used as in the first embodiment. The bottom portion 18 of the radiator H2 is the outer layer land 1
5a is attached to the dense portion by solder or the like.

According to the structure of the four-layer plate 20, the heat generated from the mounted semiconductor or general electronic component is conducted to the radiator H2 via the ground layer 12b and the plated through holes 15 and the like. . Then, the heat is dissipated in the radiator H.
It is discharged from the second fin 17 to the outside of the four-layer plate 20.
Therefore, according to the present configuration, the conventional problems relating to the temperature rise do not occur, and the shortening of the life of the electronic parts and the malfunction of the circuit due to the problems are surely eliminated.

The four-layer board 20 does not require a thick metal plate like the conventional metal board-based printed wiring board, and the plated through holes 15 themselves are formed by a special process. not. From the above, it can be seen that the excellent four-layer board 20 can be manufactured relatively easily at low cost.

Further, according to this configuration, for example, electronic parts (two-dot chain line shown in FIG. 2 (a)) P such as a large-sized LSI which generates a large amount of heat are concentrated and mounted on the outer surface of the wiring board body 11. It is effective when it has been done. That is, for the same reason as in the first embodiment, the heat dissipation is improved and the space is saved.

The present invention is not limited to the above embodiments, but may be modified as follows. For example, (a) the present invention is not limited to the multilayer plate as in the first and second embodiments, but can be embodied as a double-sided plate or a single-sided plate. In this case, the radiators H1 and H2 are connected to the heat radiation pattern connected to the ground pattern or the outer layer land of the plated through hole. The present invention can of course be embodied in a multi-layer board such as a 6-layer board or an 8-layer board.

(B) Instead of the first and second embodiments in which the radiators H1 and H2 are connected to the ground layers 2b and 12b through the plated through holes 5 and 15, they are connected via via holes. May be.

(C) Radiators H1 and H2 and heat dissipation pattern 2d or outer layer land 15a of plated through hole 15
When connecting and, it is not always necessary to use solder. (D) The solder resists 6 and 16 as in the first and second embodiments may or may not be provided.

(E) The radiator H1 of the side mounting type as in the first embodiment can be mounted not only on one side of the square-shaped double-sided plate 10 but also on two to four sides. Further, the heat radiator H2 of the top surface mounting type as in the second embodiment is not limited to the front surface side of the four-layer plate 20,
It can also be attached to the back side. Also, the number of attachments at that time can be changed as necessary.

(F) The shapes and sizes of the radiators H1 and H2 and the number of fins 7 and 17 are not limited to those shown in the first and second embodiments. For example, in the case of the side-mounting type radiator H1, it is not limited to a straight line shape, but can be changed to an L-shape or a U-shape.

Similarly, even in the case of the top-mounted radiator H2, it is not rectangular but L-shaped, U-shaped, R-shaped,
It is possible to change to any other shape. (G) By changing the configuration of the radiators H1 and H2,
It is also possible that the printed wiring boards 10 and 20 also have a function as a mounting member for fixing to the case or the like. With such a structure, more space saving can be achieved.

[0032]

As described in detail above, according to the printed wiring board of the present invention, it is possible to reliably prevent the shortening of the life of electronic parts and the malfunction of the circuit due to the temperature rise. . Further, according to this printed wiring board, in addition to such an effect, an excellent effect that it can be manufactured at low cost and relatively easily is exhibited.

[Brief description of drawings]

FIG. 1 (a) is a plan view showing a multilayer printed wiring board (four-layer board) 10 of Example 1, and FIG. 1 (b) is a partially enlarged sectional view taken along the line AA.

FIG. 2A is a plan view showing a multilayer printed wiring board (four-layer board) 20 of Example 2, and FIG. 2B is a partially enlarged cross-sectional view taken along the line BB.

[Explanation of symbols]

1, 11 wiring board main body, 2a heat dissipation pattern as conductive joint surface, 10, 20 four-layer board as multilayer printed wiring board, 12b ground layer, 15a outer layer land of plated through hole as conductive joint surface, H1 , H2
Radiator.

Claims (1)

[Claims] 1. A conductive joint surface for mounting a radiator on the outer surface of a wiring board body is provided in the outermost layer of the wiring board body, and the radiator and the ground layer or ground pattern are provided through the conductive joint surface. A printed wiring board characterized by being connected to.