JP3434552B2 - heatsink - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to LSIs having a high heat generation density such as high-speed driving microcomputers, semiconductor elements such as medium-capacity thyristors and power transistors, and heat sinks used in semiconductor-using equipment, particularly air-cooled heat generation. The present invention relates to a heat sink that is required to be diffused and cooled and to be downsized.

[0002]

2. Description of the Related Art QFP (Quad Flat Pack)
14 and 15 showing a perspective view and a side view showing an example in which a conventional heat sink is attached to an LSI of a ceramic package by aging), the heat sink 90 is made of a material having high thermal conductivity such as aluminum or copper. The QFP type L is machined so as to have the fins 92 around the heat conduction column 91, and the central portion of the column 91 serves as a heat source.
It is closely mounted on the central plane of the SI 93, and the heat generated by the LSI 93 is radiated by the fin portion 92.

[0003]

In the heat sink 90 having the above-described structure, the fins of the heat sink 90 are increased by increasing the diameter dl of the fin portion 92 or increasing the number of fins as the heat generation amount of the LSI 93 increases. A sufficient heat dissipation effect cannot be obtained unless the surface area of the portion 92 is increased. However, when d1 of the heat sink 90 is larger than the outer shape of the LSI 93 or the height H becomes too high, such a large heat sink 90 is electronically operated. If it is installed in a limited narrow space such as a device, there is a problem that convection of air is disturbed and the cooling capacity is significantly lowered.

Even if the above-mentioned means for allowing the heat sink 90 to be upsized is used, simply increasing the diameter dl of the fin portion 92 or increasing the number of fins does not mean that the heat source (LS) is used.
I93), the thermal resistance of the material of the heat sink 90 increases as the distance from the heat sink 90 increases, so that it is necessary to increase the thickness t1 of the fins or increase the diameter d2 of the heat conduction column 91, and thus the heat generation amount of the LSI. As a measure against the increase in the number of times, the size of the heat sink is often increased, and at the same time, the size of the motor such as forced convection is often increased, resulting in a high cost.

In the processing of the heat sink 90, the ratio of the diameter d2 of the heat conducting column portion 91 to the diameter d1 of the fin portion 92 is suitable for convection with the fin interval t2 in view of the relationship between the heat sink material and the strength and cutting accuracy of the cutting tool. Since there is a limit that can be cut while maintaining a constant interval, there is a limit to partial miniaturization such as thinning the fin thickness t1 of the heat sink 90.

Further, since the conventional heat sink 90 requires the heat conducting column portion 91, heat accumulation occurs in the densely stacked fins under natural convection or under a slight wind, and effective heat dissipation cannot be performed.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a small-sized and lightweight heat sink structure for improving heat dissipation performance, and to solve the above problems.

[0008]

A heat sink having a structure in which a heat receiving plate and at least one radiating fin are stacked, wherein the heat receiving plate and the radiating fin are formed of a material having excellent thermal conductivity in a flat plate shape, A slit hole penetrating from the upper surface to the lower surface is formed on the flat plate surface of the heat radiation fin so as to penetrate the flat plate surface, and a plurality of fin convex portions are formed by press working on the portion of the flat plate surface where the slit holes are not arranged. All or some of the overlapping fins are arranged at different positions on the radiating fin, and the space between the plate and the radiating fins and the overlapping radiating fins is maintained by the fin ridges. Or a motor on the heat receiving plate,
A heat sink is provided with a cooling fan attached to the rotary shaft of this motor.

The heat pipe 50 may be arranged in a part or the whole of the space formed in the heat sink 10.

[0010]

[Function] Since the heat diffused to the heat receiving plate 11 can be transmitted to the radiating fins 12 far from the multiple radiating fins 12 via each fin convex portion 12a in the shortest distance, it is excellent in heat equalization as a heat sink. At the same time, by providing the slit holes and the fin protrusions as in the above configuration, it is not necessary to consider the elongation rate of the fin material due to press working, and brazing is stable. Further, due to the structure of the slit holes and the fin protrusions, convection to the cooling air not only from the side but also from the upper surface is promptly performed, fin efficiency is improved, and as a result, the interval (pitch) between the fins can be narrowed to the limit, It is superior to the inclusion of cooling air from above, rather than simply providing many round holes.

Further, the radiation fin 12 or the heat receiving plate
11 Cooling fans that generate forced convection on one or both sides
Since the 32 are integrated and installed, the external dimensions are the same as the conventional heat sink.
If it is provided at a plurality of locations on 12 or on the side surface of the radiation fin 12, a more excellent radiation effect can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A top view of a heat sink as a first embodiment of the present invention is shown in FIG. 1, a view of this AA section taken in the direction of the arrow is shown in FIG. 2, and a BB section is taken in the direction of the arrow. The figure is shown in FIG.

In FIGS. 1 and 2, the heat sink 10 is made of a material having a high thermal conductivity, such as aluminum or copper, in the form of a flat plate.
One surface of the heat receiving plate 11 processed into a quadrangle is attached to the heating element 93 as a heat receiving surface 13, and the other surface is provided with four radiating fins 12 that effectively radiate the heat of the heat receiving plate 11.

The area of the flat surface of each of the four radiation fins 12 is substantially equal to that of the heat receiving plate 11, and the fin projections 12a formed by a number of press projections described below are formed downward of the radiation fins 12.
Are provided and are joined to the opposing surface by brazing or the like to form a space d between the respective heat radiation fins 12 to form the air flow path 20, and at the same time, the respective heat radiation fins 12 and the heat receiving plate.
It forms a heat conduction path between the and 11. Further, a convection hole 34, which is a space portion, is provided in the central portion of the flat plate of the four radiation fins 12, and a motor 30 is provided in the space portion formed by the convection hole 34. A cooling fan 32 is attached to the rotating shaft. In this embodiment, the motor 30 is arranged on the heat receiving plate 11 and the cooling fan 32 is rotated to take in the upper atmosphere into the heat sink 10 and discharge it laterally through the heat radiation fins 12. As shown in FIG. 10, the mounting positions of the motor 30 and the cooling fan 32 are such that the rotation axis is perpendicular to the heat radiating fins 12 toward the heat receiving plate 11 of the convection holes 34 of the uppermost heat radiating fins 12. The arranged motor 30 may be attached, and the cooling fan 32 may be attached to the rotating shaft of the motor 30. At this time, the end surface of the rotation shaft of the motor 30 that does not project is formed by a support column and a convection hole 34 for introducing air, and air is introduced into the cooling fan 32 also through the convection hole. The number of the motors 30 and the number of the cooling fans 32 may be plural depending on the size and shape of the radiation fins 12 to be mounted, and this mounting position need not be provided in the center of the flat surface of the radiation fins 12 as shown in FIG. The cooling fan 32 and the like may be moved to the side surface of the heat radiation fin 12 as shown in FIG.

As shown in FIG. 1, the heat radiation fin 12 is provided with a plurality of rectangular slit holes 15 so as to penetrate from the upper surface to the lower surface on the left and right with the longitudinal center axis of the flat plate surface being symmetrical. Fin projections 12a formed by pressing the heat radiation fins 12 are regularly arranged between a plurality of adjacent slit holes 15.

The radiating fins 12 differ in the shape of the fins to be overlapped. For example, the shapes of the odd-numbered portions of the first and third heat-receiving plates 11 are shown in FIG. The shape of the even-numbered portion of the upper fourth sheet is as shown in FIG. 1. As shown in FIG. 2 of this cross-sectional view, each fin protrusion 12
The structure is such that the position of a does not overlap the position of the fin protrusion 12a of the heat radiation fin 12 that overlaps. In the above configuration, the two types of heat radiation fins 12 shown in FIGS. 1 and 4 can be used in manufacturing, but for example, as shown in FIG. 6, the fin protrusions 12 a that are adjacent to each other are parallel to each other. Part 12
If all or part of a is not arranged in the same portion, one kind may be arranged reversely, and if it is press-moldable, the heat radiation fin 12 may be of any shape. Further, the slit holes 15 are independently formed on the left and right sides of the flat plate surface of the radiation fin 12, but if there is no problem in the stability of the press of the fin convex portion 12a and the production, as shown in FIG. The slit holes 15 assigned to the above may be one. The radiating fins 12 on the heat receiving plate 11 do not have to have the same outer shape as the heat receiving plate 11, and the large heat receiving plate 11 has a small radiating fin.
Various combinations are possible, such as arranging 12 pieces in a plane. Further, the slit hole 15 is not limited to a simple rectangle or one direction, and a part of the radiation fins 12 to be used is used.
Needless to say, the shapes of the slit holes 15 and the fin protrusions 12a may be changed for the convection guide or printing. In particular, the radiating fins 12 at the top of FIG. 2 are not provided with the slit holes 15, and the other radiating fins 12 are provided with the motor 30 and the cooling fan.
A larger cooling effect can be obtained by enlarging the convection holes 34 in the installation portion.

Further, in the above embodiment, the shape of the heat sink 10 is substantially square when viewed from the upper surface, but it may be circular as shown in FIG. 5 or other polygons in consideration of the mounting area, heat dissipation efficiency and the like. In addition, the radiation fin 12 of the above embodiment,
As shown in FIG. 2, the radiating fins 12 are placed horizontally and fixed by joining the bottom surfaces of the fin convex portions 12a to the heat receiving plate 11, but the number of radiating fins 12 increases and the number of stacked sheets increases. In this case, as shown in FIG. 7, the radiation fins 12 may be placed vertically and the side surfaces of the fin protrusions 12a may be fixed to the heat receiving plate 11. In this case, by bending the end edge of the heat receiving plate 11 and attaching the fin guide 11a,
The radiation fin 12 can be easily fixed.

As the material of the heat radiation fin 12, a brazing sheet in which a brazing material is clad on both sides of an aluminum core material is generally used, and the heat sink 10 temporarily fixes the uppermost heat radiation fin 12 and the lowermost heat receiving plate 11, It is lower than the melting point of the core material of the fins 12 and is placed in a heating furnace at a temperature higher than the melting point of the brazing material, and the brazing material is melted and then cooled. Of course, the heat receiving plate 11 and the fin convex portion 12a are integrally formed.

To attach the heat sink 10 to the heating element 93, in addition to the brazing, an adhesive such as a high thermal conductive epoxy resin or silver paste, or a combination of silicon grease and a dedicated clamp may be used. At this time, the heat receiving surface 13 is smaller than the outer diameter of the heat receiving plate 11 and is designed to emphasize the increase of the heat radiation area. LS
In many cases, it is preferable to attach it closely to the heating element such as I.

In the heat sink 10, the heat generated in the heating element 93 is transferred to the fin projection 12a and the entire surface of the radiation fin 12 through the heat receiving plate 11. Since the heat receiving plate 11 has an appropriate thickness with respect to its outer diameter, for example, a thickness of about 2 mm for a square having a side of 50 mm, the heat of the heat receiving surface 13 is reduced even if the area of the heat receiving surface 13 is small. The heat receiving plate 11
Is evenly transmitted to the entire surface of. On the other hand, the radiating fin 12 made of a standard brazing sheet is thinner than the thickness of the heat receiving plate 11 and is only about 0.5 mm, but the uniform heat transmitted to the heat receiving plate 11 is the first. A large number of fin protrusions 12a of the radiation fin 12 that are in direct contact with
Is transmitted to the entire surface of the heat radiating fins 12 through the heat radiating fins 12, and heat is sequentially conducted to the radiating fins 12 above through the respective fin protrusions 12a, so that the heat sink 1 as a whole has a substantially uniform heat spread and radiates heat. Be seen.

As is well known, the temperature boundary layer due to convection when the heat radiation fin 12 is provided with the slit hole 15 is as shown in FIG. 3, and in the case of a normal smooth fin not provided with this, the temperature boundary layer is as shown in FIG. It becomes like a temperature boundary layer, and in this case, the boundary film thermal resistance of the radiation fin 12 becomes extremely large. Therefore,
As shown in FIG. 3 and FIG. 8, in the radiation fin 12 having the slit hole 15, the thermal conductivity of air to the fin 12 under the forced convection is improved, and uniform radiation of the entire surface of the radiation fin 12 is achieved. It will be possible.

In the conventional heat sink 90, the heat conducting column portion 91
However, since heat accumulation occurs in the densely stacked fins under natural convection or in a slight wind, effective heat dissipation cannot be performed. Since the gap d is maintained, the heat conduction column portion 91 can be omitted.

In the heat sink having the above structure, the radiation fins
The core material of 12 uses a flat alloy such as aluminum, but this core material may be a fused metal net made of copper, aluminum or the like with openings.

In general, the heat receiving plate 11 of the heat sink is made of a metal material such as aluminum and is attached to an existing LSI (heating element) package or the like.
The heat receiving plate 11 may have a heat pipe structure in order to cope with an increase in size, or may be a ceramic plate of alumina, aluminum nitride, silicon carbide or the like in order to match a thermal expansion coefficient with a semiconductor chip, and a semiconductor such as the LSI or the like. Greater cooling effect can be obtained by directly bonding to the chip. At this time, the heat-receiving plate 11 of the ceramic plate and the heat-radiating fins 12 can be joined relatively easily by subjecting the heat-receiving plate 11 to the heat-radiating fins 12 on the joining side by printing and sintering metal such as nickel alloy. You can do it.

The second embodiment of the present invention is shown in FIGS.
It shows in FIG. 10 is a cross-sectional view taken along the line AA of FIG. 1 in the direction of the arrow, and FIGS.
It is the figure which looked at B cross section in the arrow direction. 10 and 11, the heat pipe 50 is embedded in the air passage 20 (space) formed in the heat sink 10 described in the first embodiment to promote heat equalization of the heat radiation fins 12. There is. The heat pipe 50 may be provided in all the air convection channels 20,
Alternatively, some of the air convection paths 20 may be provided in consideration of forced convection. Also, in FIGS. 10 and 11, the heat pipe 50
Is arranged so as to be horizontal with respect to the heat receiving plate 11, but is arranged so as to be vertical with respect to the heat receiving plate 11 so that the heat pipe 50 is embedded in the slit hole 15 as shown in FIG. Or, considering the forced convection,
The heat receiving plate 11 may be arranged in combination with a horizontal one and a vertical one.

Further, when there is a sufficient space for disposing the heat sink 10, as shown in FIG.
An excellent heat dissipation effect can be obtained by projecting the heat sink 10 out of the outer shape of the heat sink 10, and a more excellent heat dissipation effect can be obtained by providing the heat pipe fins 52 on all or part of this projecting portion. In FIG. 13, two protrusions are arranged on the left and two on the right, but the protrusions are arranged alternately. However, it is possible to arbitrarily design the protrusions by the intervals of the heat radiation fins 12, and the heat pipe 50 is arranged in the slit hole 15. Needless to say, similarly, a protruding portion can be added.

Although the heat pipe 50 of the above-mentioned embodiment has a rectangular cross section, an excellent heat dissipation effect can be obtained even if the shape is round or elliptical.

Further, a temperature sensor is attached to an appropriate location of the heat sink 10, the cooling fan 32 is driven only when the heat sink 10 is at a certain temperature or higher, and when the set upper limit temperature is exceeded, it is judged that the motor 30 has failed. Needless to say, the motion of the equipment to be cooled can be appropriately selected.

[0029]

As described in detail above, according to the present invention, the heat receiving plate and the heat radiating fins having excellent heat conduction are brazed at arbitrary positions, so that they are mechanically robust and uniform. It is possible to obtain a small and lightweight heat sink with a large surface area that can dissipate heat efficiently. By omitting the heat conduction pillars 91 and providing the motor 30 and the cooling fan 32, there is no heat accumulation in the heat dissipation fins 12 that are densely convected. It is possible to provide a heat sink that can promote effective heat generation and can generate effective convection without changing the conventional external dimensions.

Since the manufacturing method is not mainly based on the conventional cutting work, but is mainly based on press work and brazing work,
Even if a heat pipe is used in the space formed in the heat receiving plate and the heat sink 10, it can be supplied at a relatively low cost for heat sinks of mass-produced semiconductors such as LSI. Further, by providing the slit hole 15 and the fin convex portion 12a as in the above-mentioned configuration, it is not necessary to consider the elongation rate of the fin material due to press working, and brazing is stable. In the embodiment of the present invention, the outer shape of the heat sink 10 in the top view is shown as a quadrangle, but the heat dissipation area can be arbitrarily changed by forming this shape into a circle or a polygon, and further by making appropriate holes.

Further, the slit hole 15 is generally processed at the time of pressing, but since the fin convex portion 12a is strong, it is possible to perform the cutting process after the end of the brazing.

The distance between the heat radiation fins 12 is generally maintained at the height of the fin protrusions 12a in one direction, but the fin protrusions 12a face each other from the opposing heat radiation fins 12 at the same place. By abutting the 12a, it is possible to increase the interval between the above-mentioned overlapping heat radiation fins 12.

In the conventional heat sink, when the distance between the radiation fins 12 is narrowed, air retention occurs and the fin effect is reduced. Convective heat transfer to the cooling air is performed quickly, fin efficiency is improved, and as a result, the spacing d (pitch) between the fins can be narrowed to the utmost limit, and by incorporating the cooling fan 32, its characteristics are maximized. It can be utilized.

[Brief description of drawings]

FIG. 1 is a top view of a heat sink showing a first embodiment of the present invention.

FIG. 2 is a view of the AA cross section of FIG. 1 viewed in the direction of the arrow.

FIG. 3 is a view of the BB cross section of FIG. 1 viewed in the direction of the arrow.

FIG. 4 is a top view of a second radiating fin according to the embodiment of the present invention.

FIG. 5 is a top view of a heat sink having a circular radiation fin.

FIG. 6 is a top view of a radiation fin in which slit holes separately provided on the left and right of the radiation fin top surface of FIG. 1 are integrated.

FIG. 7 shows a heat sink in which a radiation fin is vertically placed on a heat receiving plate.

FIG. 8 is a diagram showing convection when forced convection is applied to a conventional radiation fin.

FIG. 9 is a view in which a cooling fan is attached to the side surface of the heat sink of the present invention.

FIG. 10 is a cross-sectional view of a heat sink in which a heat pipe is embedded in the air flow path of FIG.

FIG. 11 is a view of a cross section taken along the line BB of FIG. 9 as seen in the direction of the arrow.

FIG. 12 is a cross-sectional view of a heat sink in which a heat pipe is embedded in the slit hole of FIG.

FIG. 13 is a cross-sectional view in which a protrusion is provided on the heat pipe, and heat pipe fins are provided on the protrusion.

FIG. 14 is a perspective view of a conventional heat sink.

FIG. 15 is a side view of a conventional heat sink.

[Explanation of symbols]

In the drawings, the same reference numerals indicate the same or corresponding parts. 10 heat sink 11 Heat receiving plate 12 radiation fins 12a Fin protrusion 13 Heat receiving surface 20 air flow path 30 motor 32 cooling fan 50 heat pipe 52 heat pipe fins 91 Heat conduction column 95 metal plate

Claims (2)

(57) [Claims] 1. A heat sink having a structure in which a heat receiving plate and at least one radiating fin are stacked, wherein the heat receiving plate and the radiating fin are made of a material having excellent thermal conductivity in the form of a flat plate. The flat plate surface is provided with a slit hole penetrating from the upper surface to the lower surface so as to penetrate the flat plate surface, and a plurality of fin projections are formed by press working in the portion of the flat plate surface where the slit holes are not arranged, and the overlapping radiation fins All or some of the fin protrusions are arranged at different positions on the heat dissipation fin, and the space between the plate and the heat dissipation fin, and the overlapping heat dissipation fins is maintained by the fin protrusion, and the heat dissipation fin or the heat receiving plate is A heat sink with a motor and a cooling fan attached to the rotating shaft of the motor. 2. The heat pipe is arranged in a part or the whole of the space formed in the heat sink.
Heatsink as described.