JPH0210797A - Multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To seek to improve heat radiation ability by providing plural through holes for heat radiation. CONSTITUTION:A number of through holes 15 for heat radiation are provided at the periphery of a multilayer printed wiring board 10 where a conductor layer 11, an insulating layer 12, and a conductor layer are laminated. For the holes 15, copper plated regions 15a linked with copper platings at the inner peripheral feces of holes 15b are provided at the surfaces of the layers 11 and 13. Also, copper plating 12a is applied to the surface of the layer 12, but at the surface around the hole 15b is provided a part 12b that the plating is not applied intermittently and partially in the circumferential direction. This part 12b is so provided that it may collect the thermal components of the layer 12 to the hole 15b side. By providing the through hole this way, the heat is radiated through the through hole, and besides it is radiated from the surface by heat transmission through the copper plated part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a multilayer printed wiring board, and particularly to a structure for dissipating heat accumulated in an insulating layer.

[Prior Art] Heat generated from electronic components mounted on a multilayer printed wiring board can increase the temperature of the printed wiring board and deteriorate the electrical characteristics of electronic circuits formed on this printed wiring board. be.

Various methods have been proposed to solve such inconveniences due to heat generation.

There is a method of cooling a multilayer printed wiring board by natural air cooling by providing a plurality of openings in the device housing to form a natural air flow inside the device. However, this method has a low heat dissipation effect. Furthermore, this method cannot be applied when the housing is formed in a closed type due to corrosion or the like.

Another method is to use a fan motor to form an airflow to forcefully cool the device. However, in this method, since the motor is constantly rotating, there is a problem of reliability, and noise accompanying the rotation of the motor is also a problem.

Furthermore, there is a method of increasing the heat dissipation effect by providing heat dissipation fins on various electronic components. However, this method has the problem that the provision of heat dissipation fins makes the electronic components expensive and makes it difficult to mass-produce them.

In addition to the above-mentioned disadvantages, all of the above-mentioned methods have a problem in that the heat dissipation effect for the heat accumulated in the internal insulating layer is low because the methods mainly dissipate heat from the surface.

In view of these points, a multilayer printed wiring board as shown in FIG. 2, which has excellent heat dissipation properties and can effectively dissipate the heat accumulated inside the multilayer printed wiring board, has already been proposed (Japanese Patent Laid-Open No. 62
-281391).

In FIG. 2, this multilayer printed wiring board 1 includes a conductor layer 2,
It is constructed by laminating an insulating layer 3, a heat dissipation layer 4, an insulating layer 5, and a conductor layer 6 in this order, and the heat dissipation layer 4 has good thermal conductivity.
A large number of holes are drilled at positions corresponding to through holes required for wiring.

In this way, the heat that tends to accumulate in the insulating layers 3 and 5, which have poor thermal conductivity, is radiated to the outside by the heat dissipating layer 4, which has good thermal conductivity, through the through holes required for wiring.

[Problems to be Solved by the Invention] According to this method, however, although an appropriate heat dissipation effect can be obtained, since a dedicated heat dissipation layer 4 that is not necessary for wiring is provided, the number of manufacturing steps increases. There is a problem that the board becomes expensive. In addition, since the through holes used for heat radiation are necessary for wiring, terminals of electronic components are inserted, and the flow of air through the through holes is poor and the through holes do not contribute much to heat radiation. also appears.

The present invention has been made in consideration of the above points, and aims to provide a multilayer printed wiring board with excellent heat dissipation properties that prevents heat from accumulating in an insulating layer without providing a dedicated heat dissipation layer. It is.

[Means for Solving the Problem] In order to solve the problem, in the present invention, a plurality of through holes for heat radiation are provided in a multilayer printed wiring board having an insulating layer as an intermediate layer between a plurality of conductor layers.

[Function] The heat generated by the electronic components mounted on the multilayer printed wiring board and stored in the internal insulating layer is released to the outside through the heat dissipation through holes due to the difference in temperature from the outside of the printed wiring board. Ru.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing the multilayer printed wiring board of this embodiment, and FIG. 3 is a partially enlarged perspective view showing the insulating layer exposed by removing a portion of the conductor layer.

In FIG. 1, this multilayer printed wiring board 10 includes a conductor layer 1
1. An insulating layer 12 and a conductive layer 13 are laminated. In the case of this embodiment, a large number of through holes 15 for heat dissipation are provided in the periphery of the multilayer printed wiring board 10, which is an area outside the electronic component mounting area and the wiring pattern forming area of the conductor layers 11, 13. There is. These through holes 15
Copper plating is applied to the inner peripheral surface, and the conductor layer 11, the insulating layer 12, and the conductor layer 13 are penetrated.

As shown in FIG. 3 for the conductor layer 11, these through-holes 15 have a copper-plated area (
land) 15a is provided. Further, the surface of the insulating layer 12 is plated with copper 12a, but the surface around the hole 15b is provided with portions 12b intermittently and partially unplated in the circumferential direction. There is. This portion 12b is provided to collect the heat component of the insulating layer 12 toward the hole 15b.9 When a large number of such heat dissipation through holes 15 are provided, electronic components mounted on the printed wiring board 10 Insulating layer 1 which generates heat and has poor thermal conductivity
Since the heat accumulated in the through holes 1 is higher than the external temperature of the printed wiring board 10, the heat exchange principle
Heat is radiated through 5. At this time, the copper plating 12a of the insulating layer 12 is exposed to the outside through the copper plating on the inner periphery of the through holes 15 of the conductor layers 11 and 13.
Since the heat is connected to la, the heat is not only dissipated by the air flow passing through the through hole 15, but also transferred to the surface of the printed wiring board 10 by heat conduction through the copper plating part.
Heat is radiated from the surface.

Therefore, according to the embodiments described above, heat can be radiated from the insulating layer without providing a separate heat radiating layer, and it is possible to prevent the electrical characteristics from deteriorating. In this way, it is possible to prevent heat from staying inside, so there is no need to apply fins on electronic components or forced air cooling methods using motors to release heat immediately after it is generated. It gets better though.

FIG. 4 is a perspective view showing a method for further enhancing the heat dissipation effect of the above embodiment. One end of a wire 16 made of a metal material with good thermal conductivity is inserted into the hole 15b of at least a part of the heat dissipation through hole 15, and the other end of the wire 16 is connected to the printed wiring board 1-0. It was attached to the housing (not shown) in which it was stored.

In this way, the heat of the insulating layer 12 is conducted through the wire rod 16 and led to the casing, which has a lower temperature than the mounting area of the printed wiring board 10, and is radiated, thereby further increasing the heat radiation effect.

In the above embodiment, a through hole for heat dissipation was provided at the periphery of the printed wiring board, but if the through hole is not related to the mounting position of electronic components or the wiring pattern position, A through hole for heat radiation may be provided in the center.

Further, since the heat dissipation through holes do not contribute to signal transmission or power supply voltage transmission, they do not necessarily need to be copper plated.

Furthermore, the heat dissipation through holes do not all have to have the same shape, and may be different in size and cross-sectional shape.

Further, the present invention can also be applied to a multilayer printed wiring board in which different insulating layers are provided for each type of power supply voltage level.

[Effects of the Invention] As described above, according to the present invention, the heat that tends to accumulate in the internal insulating layer can be effectively radiated without providing a heat radiating layer exclusively for heat radiating.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an embodiment of a multilayer printed wiring board according to the present invention, Fig. 2 is a perspective view showing a conventional wiring board, and Fig. 3 shows the printed wiring board of Fig. 1 with a part removed. Main part cutaway perspective view,
FIG. 4 is a perspective view showing a method of using the printed wiring board of FIG. 1 to further enhance the heat dissipation effect. 10... Multilayer printed wiring board, 11.13... Conductor layer,
12...Insulating layer, 15...Through hole for heat radiation. Figure 1 1 Multilayer printed wiring board Perspective view of conventional printed wiring board Figure 2 Figure 4 Wk '3 Figure

Claims (1)

[Claims] A multilayer printed wiring board having an insulating layer as an intermediate layer between a plurality of conductor layers, the multilayer printed wiring board comprising a plurality of through holes for heat dissipation.