JPH06152172A - Circuit board in which heat pipe is embedded - Google Patents

Abstract

PURPOSE:To enhance the heat conductive property of a circuit board in which heat pipe is embedded and on which components generating much heat such as semiconductor device are mounted and to enhance the cooling effiiciency of the circuit board. CONSTITUTION:A circuit board 11 in which heat pipe is embedded is formed by burying the heat-absorbing part of flat heat pipes 17 inside a board 18 provided with circuit patterns 12 on the surface. In the circuit board, hollows 30 are formed in the heat pipe contact face of a heat-dissipating plate 19 arranged inside the circuit board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pipe embedded circuit board for mounting components such as semiconductor elements which generate a large amount of heat.

[0002]

2. Description of the Related Art A circuit board using a heat pipe has advantages such as high cooling efficiency and no need of power, and is used for cooling components such as semiconductor elements which generate a large amount of heat. As an example thereof, the present inventors have previously filed Japanese Patent Application No. 2-2
In No. 48644, "heat pipe embedded circuit board and its manufacturing method" was proposed. As shown in FIG. 6, this circuit board is of a type having circuit patterns 12 and 26 on both sides of a board 18, an insulating sheet 13 having the circuit pattern 12 on the surface, an adhesive layer 14, and a metal plate 15 for soaking. When,
Adhesive material layer 21, insulating plate 22, adhesive material layer 23, metal plate 24 for soaking, adhesive material layer 25, and insulating sheet 27 having circuit pattern 26 on the surface (lower surface side) are laminated and integrated. The heat absorbing portion 17a of the heat pipe that is flattened so as to have a flat surface parallel to the surface of the substrate 18 is embedded in the insulating substrate 16 that is formed by the insulating plate 22 and the adhesive layers 21 and 23. There is something.

The heat generated by a semiconductor element (not shown) mounted on the surface of the circuit pattern is absorbed by the heat absorbing portion of the flatly shaped heat pipe, and is radiated by the heat radiating portion at the end of the heat pipe for cooling. is there. This circuit board embeds the wide surface of the flat heat pipe on the heating surface side, so it has good thermal conductivity to the heat absorbing part, and the cooling effect is improved compared to the one using the conventional circular heat pipe. There is an advantage to However, in recent electronic circuit devices, high heat-generating components such as LSIs are mounted at high density, and the amount of heat generated by the circuit board has increased remarkably. Substrates are needed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made as a result of studying the above problems, and has developed a heat pipe embedded circuit board which further improves cooling efficiency.

[0005]

According to the present invention, there is provided a heat pipe-embedded circuit board in which a heat absorbing portion of a flat heat pipe is embedded in a board having a circuit pattern on a surface thereof. The heat pipe-embedded circuit board according to claim 1, characterized in that a recess is formed on the contact surface of the heat pipe. The heat pipe embedment according to claim 1, wherein the recessed surface is formed with an unevenness or a rough surface. A circuit board is defined as claim 2, and the heat pipe embedded circuit board according to claim 1 is characterized in that the heat dissipation plate and the heat pipe are welded.

[0006]

That is, according to the present invention, a recess is formed in the heat pipe contact surface of the heat dissipation plate arranged in the circuit board, and the wide surface of the heat absorbing portion of the flat heat pipe is closely adhered to the recess to make the contact area. Is increased, the thermal resistance is reduced, and the cooling efficiency is improved. Further, in the present invention, the thermal conductivity can be further improved by forming unevenness or a rough surface on the recessed surface. Further, by welding the heat dissipation plate and the heat pipe, the heat dissipation plate and the heat pipe are integrated, so that the thermal conductivity can be further improved. The heat radiation portion of the heat pipe may have a flat cross section or a circular cross section.

[0007]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 is a sectional view showing an embodiment of a heat pipe embedded circuit board according to the present invention, and FIG. 2 is a plan view of FIG. This circuit board 11 is a type having a circuit pattern 12 such as a copper foil on one surface of a board 18, and is made of an insulating sheet 13 having the circuit pattern 12 on the surface, an adhesive layer 14, and oxygen-free copper for heat dissipation. It is composed of a heat dissipation plate 19, an insulating substrate 16 made of glass epoxy resin or the like, and a flat heat pipe 17. Then, a recess 30 was formed on the contact surface of the heat dissipation plate 19 with the heat pipe 17 by half etching, and the wide surface of the flatly shaped heat pipe was brought into close contact therewith. The semiconductor element 31 is placed on the upper surface of the circuit board 11 thus formed, the heat generating portion 32 on the lower surface thereof is bonded to the heat generating component mounting portion 12a by the adhesive 33, and the lead portion 34 is It is connected to the circuit pattern 12 and used for semiconductor devices. The heat of the heat-generating component mounting portion passes through the heat radiating plate, and as shown in FIG.
Heat is radiated from 7b. A fin and a water cooling jacket (not shown) are provided on the heat radiating portion 17b.

On the heat dissipation plate 19 of this circuit board,
An oxygen-free copper plate with a thickness of 0.5 mm and a size of 150 × 150 mm is used, and the recess 30 has a depth of 0.2 by half etching.
Processed to 5 mm. Heat pipe is made of copper 3mmφ, length 1
Two pieces of 10 mm which were flat processed to a thickness of 2 mm were used. Further, the heat pipe 17 and the heat dissipation plate 19 used are those that have been subjected to a blackening treatment in order to maintain the adhesiveness with the epoxy resin of the insulating substrate 16. Circuit pattern 12 has 3 copper foils
5 μm of electrolytic copper is used, FR-4 of glass epoxy resin is used for the insulating substrate 16, and the insulating sheet 13 and the adhesive layer 1 are used.
4 was a laminated body, which were laminated as shown in FIG. 1 and adhered by hot pressing to form the circuit board 11.

Using the circuit board 11 produced in this way, heat-generating components each having a heat generation amount of 2 w were mounted on the heat-generating component mounting portion 12a, and the temperature after 20 minutes was measured. As a result, the circuit board of the present invention was obtained. The temperature in the vicinity of the heat-generating component mounting portion was about 35 ° C. On the other hand, the conventional circuit board is about 40
It was confirmed that the temperature was 0 ° C. and the temperature decreased by 10% or more.

Further, the depression 30 of the heat dissipation plate 19 described above.
Further, by forming the uneven portion 35 as shown in FIG. 3, the thermal conductivity of the heat dissipation plate and the heat pipe is improved, and the cooling efficiency is further improved. Further, the same effect can be obtained even if the surface is roughened by sandblasting or the like.

Further, the contact portion between the heat radiation plate 19 and the heat pipe 17 is welded as shown in FIG.
It was confirmed that the thermal conductivity was improved by forming No. 6.

Next, as shown in FIG. 5, two heat dissipation plates 19 are provided on the upper and lower surfaces so as to sandwich the heat pipe 17 to form a substrate 18, and semiconductor elements 31 are attached to the upper and lower surfaces to form a double-sided type. did. Also in this case, the heat generated from the upper and lower surfaces can be absorbed by the heat pipe through the heat radiating plate, radiated from the heat radiating portion at the other end, and efficiently cooled. Note that, in FIG. 5, the other configuration is the same as that of FIG. 1, and therefore, the same portions are denoted by the same reference numerals and the description thereof will be omitted.

[0013]

As described above, according to the present invention,
The heat resistance of the heat pipe and the heat dissipation plate is reduced, the heat dissipation is improved, the thickness of the circuit board is reduced, and the components can be easily mounted.

[Brief description of drawings]

FIG. 1 is a sectional view of a heat pipe embedded circuit board according to an embodiment of the present invention.

FIG. 2 is a plan view of the heat pipe embedded circuit board of FIG.

FIG. 3 is a cross-sectional view of a heat dissipation plate and a heat pipe contact portion according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of another example of the heat dissipation plate and the heat pipe contact portion according to the embodiment of the present invention.

FIG. 5 is a sectional view of another example of the heat pipe embedded circuit board according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional heat pipe embedded circuit board.

[Explanation of symbols]

 11 circuit board 12,26 circuit pattern 12a heat generating component mounting part 13,27 insulating sheet 14,21,23,25 adhesive material layer 15,24 metal plate 16 insulating substrate 17 heat pipe 17a heat absorbing part 17b heat radiating part 18 substrate 19 heat radiating plate 30 Depression 31 Semiconductor Element 32 Heat-generating Section 33 Adhesive Material 34 Lead Section 35 Uneven Section 36 Weld Section

Claims (3)

[Claims] 1. A heat pipe-embedded circuit board in which a heat absorbing portion of a flat heat pipe is embedded in a board having a circuit pattern on its surface, and a dent is formed on a heat pipe contact surface of a heat dissipation plate arranged in the circuit board. A heat-pipe-embedded circuit board characterized in that 2. The heat pipe-embedded circuit board according to claim 1, wherein an unevenness or a rough surface is formed on the recessed surface. 3. The heat pipe embedded circuit board according to claim 1, wherein the heat dissipation plate and the heat pipe are welded together.