JPH0888472A - Printed circuit board - Google Patents

Abstract

PURPOSE: To easily cool a multilayer substrate by providing a plurality of through holes which penetrate an insulation substrate body, a surface conductor, a reverse side conductor, and an inner-layer conductor, providing a conductor in a through hole at the inner periphery, and then connecting the surface conductor, reverse side conductor, and the inner-layer conductor. CONSTITUTION: A surface conductor 4 and a reverse side conductor 5 are formed on the front and rear surfaces of an insulation substrate body 1, respectively. A plurality of through holes 2 are provided in lattice shape so that they pass through the surface conductor 4 and the reverse side conductor 5. An inner-layer power supply plane 6 which is an inner-layer conductor is laminated in the insulation substrate body 1 and is connected to a power supply. A conductor 3 in through hole is provided at the inner periphery of the through hole 2 and the surface conductor 4, the reverse side conductor 5, and the inner-layer power supply plane 6 are connected. Not only heat generated by the inner-layer power supply plane 6 but also heat generated from the surface conductor 4 and the reverse side conductor 5 are transferred to the conductor in the through hole 2 and are cooled by the natural air convection to easily radiate heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board, and more particularly to a heat dissipation structure for a multilayer printed circuit board.

[0002]

2. Description of the Related Art Conventionally, a through hole of a general printed circuit board has not been formed in consideration of heat dissipation, but is provided for the purpose of electrical connection between conductors of a plurality of electric layers. As one example thereof, a technique disclosed in Japanese Patent Application Laid-Open No. 2-68985 is disclosed in which a front surface conductor and a back surface conductor provided on the front and back surfaces of a printed circuit board are electrically connected by through holes.

In FIG. 5, a surface mount printed wiring board 1
After a circuit pattern is formed on 01 by electroplating, resists 104 and 105 are provided on portions where plating is not required, masking is performed, and electroless plating is performed. The portions formed by electroless plating are the through holes 102 and the conductive pads 103. If the plating thickness of the conductive pad 103 is thinner than the thickness of the resist 104, alignment can be easily performed when mounting an electronic component, and a short circuit due to solder between pads can be reduced. The resist 104 is left as it is after plating and is used as insulation between the pads, but the resist 105 may be left, or another resist may be printed. In the drawings, only one side is shown, but the same applies to both sides.

By forming only the conductive pads and the through-holes by electroless plating, it is possible to form a resist that insulates the pads with good reliability even for the conductive pads having a small pad spacing. Moreover, there is an effect that mounting of the surface mount component by solder becomes easier.

[0005]

The above-mentioned prior art is one in which the through hole is formed by electroless plating and has the above-mentioned effect, but the through hole itself is provided for the purpose of electrical connection. That is clear. However, in recent years, the number of layers of the printed circuit board has increased, and the power supply wiring is often provided in the inner layer of the insulating substrate body. For this reason, it is impossible to expect natural heat dissipation from the surface like a double-sided substrate, and there is a problem that heat dissipation from the inner layer portion is extremely difficult.

Further, when a plurality of printed circuit boards are arranged horizontally and in parallel, natural convection is blocked and it is difficult to dissipate heat. In that case, heat generation of the circuit is reduced or a fan is attached to perform forced air cooling. It was customary. However, there is a limit to reducing the heat generation of the circuit, and there is a problem that an extra space is required if a fan is attached.

The present invention has been made in view of the above conventional problems, and an object of the invention according to claim 1 or 2 is to provide a multi-layered printed circuit board which easily dissipates heat.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 or 2 provides an insulating substrate body, front and back conductors provided on the front and back of the insulating substrate body, and the insulating substrate. In a printed circuit board including an inner layer conductor provided inside a main body, a plurality of through holes penetrating the insulating substrate body, the front surface conductor, the back surface conductor, and the inner layer conductor are provided, and an inner periphery of the plurality of through holes is provided. It is characterized in that a conductor in a through-hole is provided around and the front surface conductor and the back surface conductor are connected to the inner layer conductor.

[0009]

In the operation of the invention according to claim 1 or 2, the heat of the inner layer conductor is transmitted to the through hole inner conductor provided around the plurality of through holes, and is cooled by the fluid flowing through the plurality of through holes, so that the heat is radiated. Done. In the operation of the invention according to claim 2, in addition to the above operation, the fluid flowing in the through hole is forcibly flowed, so that highly efficient heat dissipation is performed.

[0010]

1 to 3 show a first embodiment, FIG. 1 is a partial plan view of a printed circuit board, FIG. 2 is a partial sectional view of the printed circuit board, and FIG. 3 is a perspective view in which a plurality of printed circuit boards are arranged. Is.

In FIG. 1, 1 is an insulating substrate body,
A front surface conductor 4 is formed on the front surface and a back surface conductor 5 (not shown) is formed on the back surface. A plurality of through holes 2 are formed in a grid pattern so as to penetrate the front surface conductor 4 and the back surface conductor 5. The state cut at the position of XX ′ in FIG.
FIG. 3 is a partial sectional view of FIG. In FIG. 2, reference numeral 6 denotes an inner layer power plane which is an inner layer conductor, which is laminated in the insulating substrate body and connected to the power source. Reference numeral 3 denotes a through hole inner conductor, which is provided around the inner periphery of the through hole and connects the front surface conductor 4, the back surface conductor 5, and the inner layer power supply plane 6. As the material of the insulating substrate body 1, glass epoxy, paper phenol, Teflon, ceramic or the like is used. Further, copper or copper alloy is usually used for the material of the front surface conductor, the back surface conductor and the inner layer power plane, but conductive materials such as gold, silver, nickel, aluminum and alloys thereof can also be used. .

Not only the heat generated in the inner layer power plane 6 but also the heat generated in the front surface conductor 4 and the back surface conductor 5 are transferred to the through hole inner conductor and cooled by natural convection of air.

According to the present embodiment, the heat generated in the multilayer printed circuit board is concentrated in the plurality of through holes and is cooled by natural convection of air, so that the heat dissipation of the printed circuit board is simplified. It can be performed.

In the present embodiment, the plurality of through holes are arranged in a grid pattern, but the present invention is not limited to this, and they can be electrically connected to each other depending on the planar shape of the front surface conductor, the back surface conductor, and the inner layer power supply plane. Any arrangement may be used as long as it is limited. Further, in the present embodiment, an example in which the inner layer power planes are laminated as one layer as the inner layer conductor has been taken as an example, but the inner layer power planes are not limited and, for example, an inner power source layer of a voltage different from the power source voltage is used together. Similar effects can be obtained even with a printed circuit board having two or more inner layer conductors. In that case, it is necessary to lay out the planar shapes of the front surface conductor, the back surface conductor, and the inner layer conductor and the positions of the through holes so that circuits of different voltages are not short-circuited.

In FIG. 3, reference numerals 10 and 11 denote printed circuit boards of this embodiment, which are arranged horizontally and in parallel with each other. The two printed circuit boards 10 and 11 are mounted on a box (not shown) and are surrounded by the box. However, as shown by an arrow A in FIG. The substrates 10 and 11 are naturally radiated. Therefore, there is no problem even if a plurality of printed circuit boards of this embodiment are arranged in this way.

[0016]

[Embodiment 2] FIG. 4 shows a second embodiment and is a vertical sectional view of a printed circuit board. Since the basic structure of the printed circuit board is the same as that of the first embodiment, the same members are designated by the same reference numerals, the description thereof will be omitted, and only different portions will be described.

The feature of this embodiment is that a metal tube 7 is inserted into the through hole conductor 3 of the through hole 2 of the printed circuit board of the first embodiment,
Insert the insulating tube 8 into close contact with the inner diameter of the metal tube 7,
The cooling liquid 9 is circulated. As the metal tube 7, a pipe having good thermal conductivity such as copper, stainless steel, or aluminum is used. The metal tube 7 is attached to the through hole 2 with solder, silver solder, or a conductive adhesive so that the metal tube 7 is firmly attached to the conductor in the through hole. Further, the insulating tube 8 to be inserted into the metal tube 7 preferably has heat resistance as well as electrical insulation, and a Teflon tube such as polytetrafluoroethylene is preferable. However, if the heat generation temperature is 40 ° C. or lower, a vinyl chloride hose or polyethylene tube is sufficient for circulating the cooling liquid 9. Water is usually used as the cooling liquid 9, and the water is sent from an unillustrated water tank, cooling device and pump to the insulating tube 8 and circulates.

The heat generated in the front surface conductor 4 and the back surface conductor 5 and the inner layer power supply plane 6 is transferred to the through hole inner conductor 3 and the metal tube 7, and circulates through the insulating tube 8 inserted in the metal tube 7. It is cooled by the liquid 9. Further, since it is electrically insulated by the insulating tube 8, there is no fear of leakage of current from the metal tube 7.

According to this embodiment, the heat generated in the multi-layered printed circuit board is concentrated on the plurality of through-hole conductors and the metal tube and is forcibly cooled by the cooling liquid, so that the efficiency is high. It is possible to dissipate heat from the printed circuit board.

In this embodiment, a cooling member such as a metal tube is attached to the printed circuit board of the first embodiment, but the present invention is not limited to this, and a multilayer structure of two or more layers shown in the modification of the first embodiment is formed. It may be mounted on a printed circuit board. Alternatively, a plurality of printed circuit boards may be arranged in parallel and horizontally, an insulating tube may be inserted in series with the metal tube of each printed circuit board, and the cooling liquid may be circulated. Further, in this embodiment, the insulating tube is inserted and attached to the metal tube, but the inner circumference and the end surface of the metal tube may be subjected to insulation treatment, and the inner diameter of the insulating tube may be fitted and connected to the outer circumference of the metal tube. .

[0021]

According to the present invention, the heat generated in the multilayer printed circuit board is concentrated in the plurality of through holes and is cooled by the fluid flowing through the plurality of through holes. Therefore, it is possible to efficiently dissipate heat from the printed circuit board. According to the second aspect of the present invention, in addition to the above effects, the cooling liquid is forcibly cooled, so that it is possible to radiate heat from the printed circuit board with high efficiency.

[Brief description of drawings]

FIG. 1 is a partial plan view showing a printed circuit board according to a first embodiment.

FIG. 2 is a partial cross-sectional view showing the printed circuit board of the first embodiment.

FIG. 3 is a perspective view showing a plurality of printed circuit boards according to the first embodiment.

FIG. 4 is a vertical sectional view showing a printed circuit board according to a second embodiment.

FIG. 5 is a vertical cross-sectional view showing a conventional printed wiring board.

[Explanation of symbols]

 1 Insulating substrate body 2 Through hole 3 Through hole Inner conductor 4 Front surface conductor 5 Back surface conductor 6 Inner layer power plane

Claims (2)

[Claims] 1. A printed circuit board comprising an insulating substrate body, front surface conductors and back surface conductors provided on the front and back surfaces of the insulating substrate body, and inner layer conductors provided inside the insulating substrate body. A plurality of through holes penetrating the front surface conductor and the back surface conductor and the inner layer conductor are provided, and a through hole inner conductor is provided around the inner circumference of the plurality of through holes to connect the front surface conductor, the back surface conductor and the inner layer conductor. A printed circuit board characterized by being configured as follows. 2. A metal pipe is inserted into a plurality of through holes formed around the conductor in the through hole, and an insulating tube is attached to the metal pipe to circulate a cooling liquid. The printed circuit board according to claim 1.