JP7259303B2 - Insulated circuit board with heat sink and electronic component module - Google Patents

Description

TECHNICAL FIELD The present invention relates to an insulating circuit board on which various electronic components can be mounted, and more particularly to an insulating circuit board with a heat sink and an electronic component module having a heat sink for dissipating heat generated by the electronic components.

Conventionally, electronic components are mounted on an insulated circuit board using solder or the like. One type of electronic component is an LED package. In recent years, LEDs have been developed for higher brightness (higher output) and smaller size.In particular, headlights, which are in-vehicle components, use more than 10 high-output LEDs. .
However, the amount of heat generated by LEDs also increases as output power increases and miniaturization advances. Therefore, if the heat is not sufficiently dissipated, the LED may be damaged due to a decrease in the amount of light or thermal runaway.
Therefore, as disclosed in Japanese Patent Laid-Open No. 2002-100001, a heat sink is attached to improve the heat radiation performance.

The heat sink (heat dissipation device for LED lighting) described in Patent Document 1 includes an air-cooled radiator made of extruded aluminum having a certain length and a certain width, and a pair of heat sinks provided on both long side edges of the radiator. The heatsink comprises a board having a plurality of circuit board mounting portions on the bottom surface, and a heatsink integrally formed on the top surface of the board in a raised shape at intervals in the width direction of the heatsink to dissipate heat. A plurality of radiating fins are provided that extend in the longitudinal direction of the vessel.

JP 2017-33831 A

However, with the heat sink described in Patent Document 1, in order to ensure sufficient heat dissipation, the size, weight, volume, etc. of the heat sink increase, resulting in an increase in the size of the entire module. In particular, since a plurality of radiating fins are arranged in a line, it becomes large in the lateral direction of the row. This lateral direction is the surface direction of the circuit board, and the increase in the size of the circuit board poses problems of limiting mounting locations and increasing costs.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides an insulated circuit board with a heat sink and an electronic component module that suppresses an increase in size in the planar direction of the board, facilitates mounting, and reduces costs. intended to provide

In the insulated circuit board with a heat sink of the present invention, a circuit layer is bonded to the surface of a ceramic substrate in a laminated state, and extends along the lamination direction of the circuit layer on the side opposite to the circuit layer of the ceramic substrate. A heat sink having a male-threaded fin portion, or a heat sink having a spiral-shaped fin portion and a male-threaded portion having a larger diameter than the spiral-shaped fin portion formed at the base end of the spiral fin portion is joined.

In this insulated circuit board with a heatsink, the fins of the heatsink are formed in a spiral shape extending along the stacking direction of the circuit layers, so that an increase in the surface area of the circuit layers can be suppressed. In this case, since the fins extend in the stacking direction, the dimension in the direction perpendicular to the surface direction of the circuit layer becomes large. As a result, the heat sink extends in the direction of its insertion, so that there is little effect on the mounting surface of the circuit layer, and problems such as the limitation of the mounting portion are less likely to occur, and cost reduction can be achieved.
Moreover, since the fins of the heat sink are spirally formed, the surface area is large and the heat exchange performance is good.

In one embodiment of the insulated circuit board with a heatsink, the ceramics substrate and the heatsink may be bonded via a buffer layer made of pure aluminum.

Since the buffer layer made of pure aluminum is interposed, the occurrence of thermal stress in the ceramic substrate due to the difference in thermal expansion and contraction between the ceramic substrate and the heat sink can be alleviated, and cracks and the like of the ceramic substrate can be prevented. So-called 4N aluminum having a purity of 99.99% or higher is suitable as pure aluminum.

In another embodiment of the insulated circuit board with a heat sink, the heat sink may be provided with a flange portion extending in a direction perpendicular to the stacking direction at an end portion on the ceramic substrate side.

The flange portion facilitates attachment to a heat exchanger or the like. Even in this case, since the fins extend in the stacking direction, the area of the flange portion in the direction orthogonal to the stacking direction can be kept to a minimum size necessary for attachment and the like.

In the electronic component module of the present invention, an electronic component is mounted on the circuit layer of the insulated circuit board with a heatsink, and the heatsink has the fins inserted into the flow paths of the heat exchanger and has the male screw shape. A fin portion or an externally threaded portion is screwed and fixed in a threaded hole in the wall of the heat exchanger .

In this electronic component module, the fins of the heat sink are inserted and fixed in the heat exchanger. can be made small, which is advantageous for miniaturization.

ADVANTAGE OF THE INVENTION According to this invention, while suppressing the enlargement in the surface direction of a board|substrate, while facilitating mounting, cost reduction can be aimed at.

1 is a perspective view showing a state in which an electronic component is mounted on an insulated circuit board with a heat sink according to an embodiment of the present invention; FIG. 2 is a plan view of an insulated circuit board with a heat sink on which the electronic component shown in FIG. 1 is mounted; FIG. 1. It is a perspective view which shows a mode that the insulated circuit board with a heat sink which mounts the electronic component of FIG. 1 is attached to a heat exchanger. FIG. 2 is a cross-sectional view of a pressurizing device for manufacturing an insulated circuit board with a heat sink; FIG. 2 is a perspective view similar to FIG. 1 showing another example of an insulated circuit board with a heat sink;

Hereinafter, embodiments of an insulated circuit board with a heatsink and an electronic component module of the present invention will be described.
As shown in FIGS. 1 to 3, the electronic component module 1 of the embodiment has an electronic component 30 mounted on an insulated circuit board 20 with a heatsink and a heatsink 40 attached to a heat exchanger 50 . The insulating circuit board 20 with a heat sink has a configuration in which a heat sink 40 is provided on an insulating circuit board 10 with a buffer layer 15 interposed therebetween. These will be described in detail below.

As shown in FIG. 1, the insulating circuit board 10 includes a ceramic substrate 11, a circuit layer 12 bonded to one surface (front surface) of the ceramic substrate 11, and a circuit layer 12 bonded to the other surface (back surface) of the ceramic substrate 11. and a metal layer 13 .
The ceramic substrate 11 is an insulating material that prevents electrical connection between the circuit layer 12 and _the metal layer ₁₃ , and is made of, for example, aluminum nitride (AlN), alumina ( _Al2O3 ), silicon nitride ( _Si3N4 ), or the like. and has a plate thickness of 0.2 mm to 1.5 mm. The plane size is formed in a square or rectangle of 5 mm or more and 20 mm or less.

The circuit layer 12 is formed by joining a plate material made of aluminum or an aluminum alloy to the upper surface of the ceramic substrate 11, and has a thickness of 20 μm or more and 50 μm or less.
Moreover, the planar size of the circuit layer 12 is 5 mm or more and 20 mm or less, and is formed in a size that is arranged within the plane of the ceramic substrate 11 .
The metal layer 13 is formed by bonding a plate material made of aluminum or an aluminum alloy to the lower surface of the ceramic substrate 11, and has a thickness of 20 μm or more and 50 μm or less.
Moreover, the plane size of the metal layer 13 is 5 mm or more and 20 mm or less, and is formed in a size that is arranged within the plane of the ceramic substrate 11 .
The circuit layer 12 and the metal layer 13 preferably have the same material, the same thickness, and the same planar size, but they may be formed with different materials, different thicknesses, and different planar sizes. Although the material is not necessarily limited, JIS No. 3000 aluminum is preferable.

The heat sink 40 has a flange portion 41 at its base end, and a threaded fin portion 42 extending in a direction perpendicular to the surface direction of the flange portion 41 is integrally formed at the center of the flange portion 41 . As a material for the heat sink 40, for example, JIS No. 6000 aluminum alloy is suitable.
The flange portion 41 is formed in a plate-like shape having a thickness of 1 mm or more, and its planar shape is the same as or larger than the planar shape of the insulating circuit board 10. For example, it protrudes outside the insulating circuit board 10 by about 2 mm. is formed in In the illustrated example, the flange portion 41 is formed in a hexagonal shape in plan view so as to be able to engage with a hexagonal bolt tool (spanner, wrench). This flange portion 41 is joined to the metal layer 13 of the insulated circuit board 10 via the buffer layer 15 .
The fin portion 42 has a structure in which spiral fins 44 are integrally formed around a shaft 43 . The dimensions of each part are not necessarily limited, but the length of the shaft 43 is 5 mm or more and 40 mm or less, and the outer diameter of the shaft 43 is 5 mm or more and 20 mm or less. The protrusion height of the fins 44 from the outer peripheral surface of the shaft 43 is 0.5 mm or more and 2 mm or less, and the pitch of the fins 44 is formed to be about 1 mm.

The buffer layer 15 interposed between the metal layer 13 of the insulating circuit board 10 and the flange portion 41 of the heat sink 40 is formed of pure aluminum into a plate shape having a thickness of 1 mm or more and 2 mm or less. As pure aluminum, aluminum with a purity of 99.00% by mass or more or a purity of 99.99% by mass or more is used, and so-called 4N aluminum with a purity of 99.99% by mass or more is suitable.

A method of manufacturing the insulated circuit board 20 with a heat sink configured in this way will be described.
First, an aluminum plate serving as the circuit layer 12 is laminated on one surface of the ceramic substrate 11, and an aluminum plate serving as the metal layer 13 is laminated on the other surface through a brazing material. As the brazing material, an Al--Si based brazing foil is used, and an Al--Ge based, Al--Cu based, Al--Mg based, Al--Mn based, or Al--Si--Mg based brazing material can also be used.
After laminating aluminum plates on both sides of the ceramic substrate 11 via a brazing material, the laminate is heated in a vacuum atmosphere while being pressurized with a pressure of 0.3 MPa, for example. In this case, since the aluminum plate is thin, it is first preheated to about 540° C. and then heated to about 610° C. so that the brazing material component does not seep out from the interface between the ceramic substrate 11 and the aluminum plate to the opposite side of the aluminum plate. do. As a result, the aluminum plate is bonded to the ceramic substrate 11 to produce the insulated circuit board 10 having the circuit layer 12 and the metal layer 13 on the surface of the ceramic substrate 11 .

Next, the insulating circuit board 10 is laminated on the flange portion 41 of the heat sink 40 with a pure aluminum plate serving as the buffer layer 15 interposed therebetween.
The heat sink 40 is formed by subjecting a rod-shaped block made of an aluminum alloy to press molding, cutting, or the like.
A pure aluminum plate serving as a buffer layer 15 is laminated on the upper surface of the flange portion 41 of the heat sink 40 via an Al-Si brazing material, and an insulation circuit is formed on the pure aluminum plate via an Al-Si brazing material. A substrate 10 is laminated. Al--Ge, Al--Cu, Al--Mg, Al--Mn or Al--Si--Mg brazing filler metals can also be used.

Then, this laminate is set in a pressure device 60 shown in FIG.
The pressurizing device 60 includes a base block 61, a plurality of guide posts 62 vertically attached to the upper surface of the base block 61, and movably supported on the upper ends of these guide posts 62 along the guide posts 62. A backup plate 63, a pressure plate 64 supported by a guide post 62 so as to be vertically movable between the base block 61 and the backup plate 63, and a pressure plate 64 provided between the backup plate 63 and the pressure plate 64 and an urging means 65 such as a spring for urging downward. The backup plate 63 and the pressure plate 64 are arranged parallel to the upper surface of the base block 61 .
The base block 61 and pressure plate 64 are made of carbon.

At least one pair of the guide posts 62 are vertically provided on the upper surface of the base block 61 and have a threaded portion 62 a formed at the upper end thereof. In this embodiment, a hole 61a is formed vertically inside the guide post 62 of the base block 61 and opens to the upper surface of the base block 61 . The hole 61 a is formed with an inner diameter larger than the outer diameter of the fin portion 42 of the heat sink 40 and is formed deeper than the length of the fin portion 42 . The flange portion 41 is supported in contact with the upper surface of the base block 61 with the fin portion 42 inserted into the hole 61a.

With the fin portion 42 of the heat sink 40 inserted into the hole 61a, the insulating circuit board 10 is placed on the flange portion 41 on the upper surface of the base block 61 with an aluminum plate 15' serving as the buffer layer 15 interposed therebetween. For example, the layers are laminated through an Al—Si based brazing material using flux.
By screwing a nut 66 onto the threaded portion 62a of the guide post 62 while sandwiching the stack between the base block 61 and the pressure plate 64, the stack is pressed in the stacking direction. The pressure in the stacking direction is set to 0.3 MPa to 1.5 MPa, and the substrate is heated to about 600° C. in a nitrogen atmosphere.

By pressurizing, heating, and cooling the laminated body in this way, the flange portion 41 of the heat sink 40, the aluminum plate 15' serving as the buffer layer, and the insulating circuit board 10 are joined together. The insulated circuit board 20 with a heat sink is formed to which the flange portion 41 of the heat sink 40 is joined via the .
An electronic component 30 such as an LED is mounted on the circuit layer 12 of the insulating circuit board 20 with a heat sink by soldering.

The insulating circuit board 20 with a heat sink on which the electronic component 30 is mounted is attached to the heat exchanger 50 as shown in FIG. This heat exchanger 50 is a cooler using water as a heat medium, and is for cooling the heat generated in the electronic component 30 . The heat exchanger 50 has a box-shaped jacket 51 connected to an inlet pipe 52 and an outlet pipe 53 for a heat medium.
A screw hole 54 is formed to penetrate the upper wall 51a of the jacket 51, and the fin portion 42 of the heat sink 40 is screwed into the screw hole 54. As shown in FIG. By screwing the fins 42 of the heat sink 40 into the screw holes 54 and fixing the heat sink 40 to the upper wall 51 a of the jacket 51 , the electronic component 30 mounted on the insulating circuit board 10 is arranged above the jacket 51 . .

In the electronic component module 1 assembled in this manner, the fins 44 of the heat sink 40 are formed in a spiral shape extending in the stacking direction of the insulating circuit board 10, so that the increase in the surface direction of the insulating circuit board 10 can be suppressed. can. For this reason, there are fewer restrictions on mounting sites. Further, since the fins 44 are spirally formed, they can be used as external threads, and can be attached to the jacket 51 by being screwed into the screw holes 54 formed in the upper wall 51a of the jacket 51. Since there is no need to provide a hole or the like for the heat sink, the size can be reduced, the manufacturing process can be simplified, and the cost can be reduced.

In the electronic component module 1 , coolant is supplied into the jacket 51 from the inlet pipe 52 and discharged from the outlet pipe 53 . The heat generated by the electronic component 30 is transmitted to the heat sink 40 via the insulating circuit board 10 , conducts through the heat sink 40 , and is released from the fins 42 to the heat medium (coolant) within the jacket 51 . In this case, since the heat sink 40 has spiral fins 44 around the shaft 43, the heat sink 40 has a large surface area and can quickly exchange heat with the refrigerant.

In addition, although the fins are used as the male threaded portion in the embodiment, the male threaded portion for attachment having a diameter larger than that of the fins may be integrally formed on the base end portion of the shaft separately from the fins.
For example, in the insulated circuit board 21 with a heatsink shown in FIG. The male screw portion 46 is smaller than the flange portion 41 in plane size, but larger than the fin portion 42 . Then, the female threaded hole 54 of the heat exchanger 50 is formed to have a size that allows the male threaded portion 46 to be screwed thereon, the fin portion 42 is inserted into the jacket 51 of the heat exchanger 50, and the male threaded portion 46 is By screwing in, the insulated circuit board 21 with a heat sink can be attached and fixed to the heat exchanger 50 .

In addition, the present invention is not limited to the embodiments described above, and various modifications are possible.
For example, although one insulating circuit board 10 is joined to the flange portion 41 of the heat sink 40 in the embodiment, a plurality of insulating circuit boards 10 may be joined.
Although the heat exchanger 50 is of a water-cooled type, it may be of an air-cooled type using air as a heat medium.
The circuit layer may have a two-layer structure of an aluminum layer bonded to the ceramic substrate and a copper layer bonded thereon.
Either the circuit layer or the metal layer, or both, may be formed of copper or a copper alloy.
Alternatively, the heat sink may be made of copper or a copper alloy, which has a higher thermal conductivity than aluminum. If the heat sink is made of copper or a copper alloy, and if the water-cooled heat exchanger 50 is used, the surface should be plated with nickel or the like to prevent corrosion.

1 electronic component module 10 insulating circuit board 11 ceramic substrate 12 circuit layer 13 metal layer 15 buffer layers 20, 21 insulating circuit board with heat sink 30 electronic components 40, 45 heat sink 41 flange portion 42 fin portion 43 shaft 44 fin 50 heat exchanger 51 Jacket 51a Upper wall 52 Inlet pipe 53 Outlet pipe 54 Screw hole 60 Pressure device 61 Base block 61a Hole 62 Guide post 63 Backup plate 64 Pressure plate 65 Biasing means

Claims (4)

A heat sink having a circuit layer bonded to the surface of a ceramic substrate in a laminated state, and having a male-threaded fin portion extending along the lamination direction of the circuit layer on the opposite side of the ceramic substrate to the circuit layer, Alternatively, an insulated circuit board with a heat sink, wherein a heat sink having a helical fin portion and an externally threaded portion having a diameter larger than that of the helical fin portion formed at the base end of the spiral fin portion is joined. 2. The insulated circuit board with a heat sink according to claim 1, wherein said ceramic substrate and said heat sink are joined via a buffer layer made of pure aluminum. 3. The insulated circuit board with a heat sink according to claim 1, wherein the heat sink has a flange portion extending in a direction orthogonal to the stacking direction at an end portion on the ceramic substrate side. An electronic component module using the insulating circuit board with a heat sink according to any one of claims 1 to 3, wherein an electronic component is mounted on the circuit layer of the insulating circuit board with a heat sink, and the heat sink: The fin is inserted into the flow path of the heat exchanger, and the male-threaded fin portion or the male-threaded portion is screwed into a screw hole in the wall of the heat exchanger and fixed. Electronic component module.

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