RU184729U1 - RADIATOR FOR COOLING ELECTRONIC DEVICES - Google Patents

Abstract

The utility model relates to cooling systems of electronic devices, including for high-power industrial electronics, namely to radiators that perform heat exchange between the body of electronic devices and the cooling medium.

The technical result achieved by the claimed utility model is to increase the efficiency of heat transfer and assembly of the radiator design by increasing the area of the cooled surface while reducing heat conduction losses, with the possibility of connecting structural elements of unlimited sizes and made of homogeneous and heterogeneous materials.

The technical result is achieved by using a radiator for cooling electronic devices, containing a base made of metal with a heat sink attached to it. In this case, the radiator is made of plastic non-ferrous metals, and the heat sink surface is corrugated, where the corrugations form vertically oriented fins, inseparably connected to the base by cold welding by pressure along the adjacent vertices of the corrugations of the corrugations, forming grooves between the ribs. 20 s.p. f-ly, 4 ill.

Description

Utility Model Description

Purpose and scope

The utility model relates to cooling systems of electronic devices, including for high-power industrial electronics, namely to radiators that perform heat exchange between the body of electronic devices and the cooling medium.

State of the art

The effective use of powerful modern semiconductor devices involves their effective cooling. Since the beginning of the era of semiconductors, pressed or cast aluminum radiators have been used to cool them. However, today these radiators can no longer provide the required cooling of modern electronic components with a high specific power density due to the limited and undeveloped cooling surface associated with the large thickness of the radiator fins.

Known cooler for power semiconductor device [A.S. No. 1229982, IPC: Н05К 7/20, H01L 23/34], in which a corrugated insert is introduced into the intercostal space of the radiator to increase cooling efficiency, which redistributes the air flow along the height of the rib.

The disadvantage of this device is the low cooling rate and the need to use an external fan.

In the heat exchange element [A.S. No. 1409848, IPC: F28F 3/02] to intensify heat transfer, use perforated corner elements that turbulence the flow at the ends of the elements, creating additional speed for the boundary layer on the back of the corner elements.

The disadvantage of this device is that the increase in heat transfer intensity occurs only due to turbulence of the flow core with a relatively small radiator cooling surface.

Known thermal plate radiator [see US patent No. 6698500, IPC F28F 7/00, published March 2, 2004] containing a base in the form of a metal plate with parallel ribs on two opposite sides. Between the inner opposite ribs in the plate, parallel slots are made in which radiator plates of metal are fixed, the thermal conductivity of which is different from the thermal conductivity of the metal of the plate and ribs.

Known radiator provides more intense heat dissipation by the central part of the radiator. A disadvantage of the known radiator is a rather complicated and laborious technology for its manufacture.

The solution of radiators made using DAU Bonded Fin technology is also known (http://www.symmetron.ru/suppliers/dau/radiator.shtml). These radiators consist of a pressed aluminum base (base plate) and fins attached to it. To connect the ribs with the base plate, a special high-density epoxy resin is used, which ensures optimal heat flow from the base plate to the ribs, because This material has a much higher thermal conductivity compared to other epoxy materials, which allows to achieve maximum thermal performance compared to known assembly methods. The features of the technology used provide high strength of the connection of the ribs with the base plate, able to withstand large mechanical stresses, including high-frequency vibration. The base plate is made of aluminum with high thermal conductivity. Moreover, the ribs are made of technically pure aluminum and have a 15% better thermal conductivity compared to stamped ribs. However, the disadvantages of this solution include the low strength of the connection of structural elements, the technological complexity of the assembly and the limited use for various materials and sizes, as well as the presence of heat conduction losses in the bonding areas of structural elements, and the use of an environmentally harmful assembly process.

From the publications disclosed in the prior art, patent information KR20140118603; JP2004273479, JP2006310486, US2006 / 0187643, US2011 / 0031612, FR2793717 known design of radiators in which the heat sink surface of the radiator is corrugated. In this case, to connect the corrugation and the base of the fin radiators, soldering, chasing with simultaneous gluing with epoxy resin, mechanical adhesion using thermal paste, or fusion welding of the radiator base, leading to the mechanical fixing of the copper corrugation in the aluminum base of the radiator, are used. The use of solder, resin, thermal paste or embossing leads to the formation of a heat-resistant surface that prevents heat from the base of the radiator to the corrugation, which is the main disadvantage of these radiators, limiting their practical use. If copper corrugation and an aluminum base are used, then the copper rib is mechanically clamped into the base groove by the flow of molten aluminum, which makes it difficult to remove heat from the base to the corrugation. The heat-resistant surface between the base and the corrugation does not disappear. In addition, the assembly of these structures is very difficult and practically not implemented when using a radiator base of large thickness, for example, 10.0-20.0 mm and above, as well as a large area of more than 10,000 mm ² , and the use of epoxy resins and solders is environmentally friendly harmful process of making ribbed radiators.

The closest in technical essence and combination of essential features to the claimed technical solution is the radiator adopted for the prototype for the electronic component [see Patent RU No. 2217886, IPC Н05К 7/20, published November 27, 2003] containing a plurality of separate radiator plates mechanically bonded to each other in their connecting part to form a heat-absorbing part in contact with the heat-generating surface of the electronic component. Parts of the radiator plates opposite the heat-absorbing part are separated from each other and together form heat-removing parts. A plurality of radiator plates are fastened together by fixing means. Between the radiator plates there are many spacers, each of which is located between the connecting parts of adjacent radiator plates to provide a gap between the heat sink parts of the radiator plates.

The well-known radiator allows you to assemble different heat dissipation capacities from the same elements of the device, however, it has insufficient heat transfer efficiency associated with different heat dissipations of the radiator plates located in the heat-absorbing part, directly beneath the heat-generating element and at a distance from it, it is distinguished by the complexity of assembly and limited use for various materials as part of the structure and its standard sizes, as well as the presence of heat conduction losses.

Utility Model Essence

The problem solved by the claimed utility model is to develop a radiator for an electronic component that is easy to assemble, providing a reliable connection of the fins and the base of the radiator of the same and unlike metals with different ratios of the thickness of the rib and the size of the base; and allowing to improve its thermal conductivity due to the efficiency of heat exchange between the body of electronic devices and the cooling medium over a large area of the heat sink without limiting the dimensions of the radiator.

The technical result achieved by the claimed utility model is to increase the efficiency of heat transfer and assembly of the radiator design by increasing the area of the cooled surface while reducing heat conduction losses, with the possibility of connecting structural elements of unlimited sizes and made of homogeneous and heterogeneous materials.

The claimed technical result is achieved by using a radiator for cooling electronic devices containing a base made of metal with a heat sink attached to it, different from the prototype in that the radiator is made of plastic non-ferrous metals with ductility with a relative elongation of at least 40%, and heat sink the surface is corrugated, where the corrugations form vertically oriented ribs that are inseparably connected to the base by cold welding by pressure along the adjacent tires corrugation troughs forming the grooves between the ribs.

In a preferred embodiment of the utility model, the heat sink surface is made of aluminum, in particular with a thickness of not more than 2.0 mm

In another embodiment of the utility model, the base may be made of copper. It is also possible to perform a heat sink surface of homogeneous materials with the same or comparable thermal conductivity. In another embodiment of the utility model, it is possible to make a base and a heat sink surface from materials with different thermal conductivities.

In yet another embodiment of the utility model, the tops of the corrugations of the corrugations of the heat sink surface are opposed to the base of the depressions. In this case, embodiments are possible in which the tops of the corrugations of the corrugations can be made in a U-shape or have a curved shape, and the side, vertically oriented walls of the corrugations are made perpendicular to the base, or at an angle to it, with the formation of trapezoidal cross-sectional shapes of the corrugations. In another possible embodiment of the utility model, the vertices of the corrugations of the corrugations adjacent to the base are flattened, and the sides of the corrugations are counter-inclined to form an angle at the vertices opposite to the base.

In accordance with the claimed solution of the utility model, for any of the above embodiments, the one-piece cold-welded connection of the base with adjacent vertices of the corrugations of the corrugations of the heat-conducting surface is made longitudinal along the length of the corrugation. Moreover, in one embodiment, the longitudinal connection is made in the form of contact areas distributed longitudinally along the length of the corrugation, for example, point-like or in the form of short uniformly distributed contact areas that are rectangular in plan.

In yet another embodiment of the utility model, the base may be further provided with an additional contact plate located at the base of the opposing base provided with a heat sink surface. In this case, preferably, the contact plate is made of copper.

In another possible embodiment, the base may be further provided with a round hole for mounting a semiconductor device, preferably located in the center of the base of the radiator.

A brief description of the drawings.

The inventive utility model is illustrated by drawings, where:

figure 1 is a perspective view of the inventive radiator;

figure 2 organization of the connection of the base with the corrugations: a) using a plate punch with one working protrusion and formed by a continuous seam; b) using a plate punch with a set of working protrusions with a contact pad of a rectangular shape;

figure 3 the organization of the connection of the base with the corrugations using roller punches with a set of working protrusions, forming a radiator of increased area and length;

figure 4 shows in a perspective view of the inventive radiator, equipped with a contact copper plate.

It should be noted that the accompanying drawings illustrate only one of the most preferred embodiments of the utility model and cannot be considered as limitations on the content of the utility model, which includes other possible options for its implementation.

Feasibility of utility model.

As shown in FIG. 1-4 examples of the utility model, the radiator, according to the claimed solution, consists of a base 1 connected to a heat sink surface 2, which is a corrugated surface, corrugations 3, which form the edges of the heat sink surface. In this case, along the lower, adjacent to the base, vertices of the depressions forming the grooves 4 between the ribs 3, the corrugations 3 are connected to the base 1 by cold pressure welding, the contact sections of the welded joint 5 of which are distributed longitudinally along the groove of the ribs along the entire length.

In accordance with the stated solution, the corrugation of the heat sink surface is carried out by repeatedly bending the sheet material, for example, in the form of foil, tape, etc., using any bending device known from the prior art. To ensure maximum heat transfer and an efficient process for manufacturing a corrugated surface, the thickness of the walls of the corrugations forming the ribs preferably does not exceed 1/10 of the thickness of the base, and their height is limited by the stability of the punches 6 when they are incorporated into the corrugation metal during the welding process. Thus, the height of the corrugation is almost unlimited, which can significantly increase the surface of the heat sink, thereby increasing the heat transfer efficiency. Moreover, the minimum width of the groove of the corrugations formed by the lower vertices of the corrugations adjacent to the base depends on the bending strength of the punch, which determines the actual distance between the ribs. In a preferred embodiment, the corrugations of the heat sink surface are U-shaped, preferably of a rectangular cross-sectional profile. However, the corrugations can also be made with rounded apexes of the protrusions, as well as in the form of a tapering, expanding trapezoid, wavy, etc. the cross-sectional shape, which allows for the formation of the most efficient heat sink surface due to the possibility of choosing its configuration and thus giving the given structural element the specified heat transfer properties, due to the choice of the total heat sink area and the formation of corrugated air channels of various shapes to enhance heat transfer.

Cold welding of metals of the base material and the corrugations of the heat sink surface occurs due to their intense plastic deformation, leading to the flow of metal in the welding zone, which removes oxide films from the metal surface from the metal zone, which prevent the formation of a solid monolithic compound. The weldability of metals during cold welding depends on their ductility and the quality of surface preparation, the more ductile the metals, the smoother and cleaner their surfaces, the better they are welded. At the same time, the welding process is carried out without heating the metal. The absence of heating allows one to obtain welded joints of unlike metals, for example, copper and aluminum, without the formation of brittle intermetallic compounds in the joint zone, which lead to low strength and a significant decrease in the reliability of these welded joints.

According to the claimed solution of the utility model, the base and heat sink surface are made of ductile, preferably highly ductile non-ferrous metals with ductility (degree of relative deformation) of at least 40%, which allows for reliable connection of structural elements by cold pressure welding. In a preferred embodiment of the utility model, presented as an example of implementation, the base and corrugated heat sink surface can be made of electrical aluminum (ductility 55-60%), as well as copper (ductility 85-90%). Moreover, the implementation of the base and the heat sink surface can be made of both heterogeneous and homogeneous materials, since both materials are highly plastic and provide the possibility of their joining by cold pressure welding. However, within the framework of the stated decision, the above structural elements can also be made of other highly plastic metals, for example: nickel (plasticity 85-90%), silver (plasticity 80-85%, gold (plasticity 40-45%) and the like them metals and alloys in homogeneous and heterogeneous combinations.

The actual process of plastic deformation of metals is carried out by introducing steel punches of die tooling into the welded structural elements, in the zone of their connection. The shape of the punches is selected depending on the preferred type of connection. In particular, cylindrical, rectangular and shaped punches can be used. In this seam welding, it is preferable to use rollers provided with working protrusions. The necessary pressure is provided by screw, hydraulic, lever and eccentric presses.

So in the examples of implementation of the utility model, in FIG. 2a) and 2b), an embodiment of cold welding is presented using 6 hardened steel plates as punches, which are placed in the grooves of the corrugated heat sink surface of the radiator and are inserted into the corrugation and the base of the radiator during welding under the action of the upsetting force. This option allows you to form simultaneously welded joints for the entire length of the joined structural elements, with the formation of a single contact section 5 in the form of a continuous linear seam, in the case of a punch 6 with one, made on the entire length, the working protrusion 8 (Fig. 2A), or evenly located contact sections 5 in the form of recesses corresponding to the working protrusions 8 of the punch (figb). Figure 3 shows another example of the formation of a welded joint by using a roller 9 punch, with working protrusions distributed around the circumference 8. This solution also allows forming during rotation of the roller as a continuous seam (if there is a working protrusion made along the entire circumference of the roller), and in the form of contact sections of the joint evenly spaced along the length of the groove. The dimensions of the contact sections 5 are determined by the geometric dimensions of the working protrusions 8 of the punches and the general parameters of the cold pressure welding process.

A durable, one-piece connection is formed when the surfaces to be welded come closer to a distance commensurate with the parameters of their crystal lattices, which contributes to the integration of electronic shells as a result of the formation of metal bonds between surfaces when high pressures are applied. Thus, along with the ductility of the metals being welded, pressure is among the main characteristics of the process. Depending on the composition and thickness of the metal being welded, the pressure, as a rule, is 150-1000 MPa. A large compressive force ensures the rupture of oxide films, their crushing and the formation of clean surfaces, capable of setting. Thus, the boundary of the compound ceases to be a barrier and mutual diffusion of atoms occurs, accompanied by structural changes in the contact zone and plastic deformation with the release of a large amount of heat, thereby forming a monolithic compound.

Thus, the use of cold welding allows you to get cold-welded radiators from the same and unlike metals, without limiting the area of the base of the radiator. At the same time, the corrugations can be made of foil, as well as tape, with a thickness not exceeding 1/10 of the thickness of the base, preferably not exceeding 2 mm, to ensure the most efficient welding process and forming the heat transfer surface.

The process of connecting the heat exchange surface and the base of the radiator can be carried out as follows. By machining, the required radiator base is made of aluminum or copper with a thickness of not more than 30.0. Further, from a tape, for example, made of electrotechnical aluminum with a thickness of 1.0 mm, in a bending device (stamp), corrugated ribs of the required profile are obtained by repeated bending, for example, a rectangular cross-sectional shape. The mating surfaces of the corrugations and the base are cleaned with rotating steel brushes in the stripping device and further, the cleaned corrugations and the base are installed in a welding stamp, which is rigidly fixed to the upper and lower plates of the hydraulic press. At the same time, the radiator base is fixed in the lower part of the stamp, and the corrugation is installed in the upper part of the stamp, between lamellar punches that enter into the grooves of the corrugation during welding during press upsetting. The thickness of the plate punches corresponds to the width of the groove of the corrugations, and the length of the punch is equal to the length of the rib of the corrugation. The height of the plate punch exceeds the height of the ribs of the corrugation.

To form the contact sections of the weld, at the end of the plate punch there are working protrusions, which, when the press is upset, are embedded in the corrugation metal and base, producing plastic deformation of the metal necessary for the formation of a welded joint. The number of plate punches corresponds to the number of grooves of the corrugation plus two punches along the edges of the corrugation.

All contact areas (welded points-recesses) from the introduction of the working protrusions of the punches are formed simultaneously along the width of the base. After completion of the welding process (upsetting of the press), the upper die plate together with the press plate returns to its original position. Lamellar punches, rising up together with the stamp plate, come out of the grooves of the welded corrugation. The cooling radiator assembled in this way is removed from the die.

The working protrusions at the end face of the plate punch can be made both in the form of a protrusion continuous along the contour, with the formation of a continuous seam, and in the form of a set of working protrusions distributed along the length of the punch, which make it possible to form a dashed seam line, the contact sections of which have a shape corresponding to the shape of the punch protrusion : rectangular, rounded, other shape, permissible technological process.

The upsetting force (the force of introduction of the working protrusion of the punch) for one radiator rib length in the case of using the punch with one continuous working protrusion is 1.5-2 times greater than the upsetting force of the punch with several working protrusions. However, the use of a punch with a continuous working protrusion leads to an increase in metal consumption and the need to use a high-power press. Thus, the use of a punch with a contour that is continuous along the contour is justified in the production of a radiator with increased strength of the corrugation and base connection.

When choosing the shape of the contact pad of the working protrusion of the punch, and the corresponding contact pad of the connected elements, take into account that when welding two sheet elements, the weld point is in the center of these sheets, while the tensile strength of the joint is almost the same for a rectangular working protrusion and a cylindrical one. When testing for shear (bending), with the application of shear forces perpendicular to the length of the rectangular point, the strength of the rectangular point is higher than the round strength by 15-20%.

In the claimed solution of the utility model, due to the need to increase the heat from an electronic device, it is advisable to increase the area of the ribbed, corrugated surface of the radiator by increasing the number of ribs of the corrugation, in particular by reducing the distance between the ribs.

For this, as previously indicated, it is preferable to use punches in the form of thin plates with a rectangular contact area of the working protrusions (plates with rectangular working protrusions), due to the higher manufacturability of their manufacture.

When a punch is inserted into the mating surfaces of a rectangular working protrusion, the metal flow is uneven, mainly in two opposite directions along the width of the contact area of the working protrusion and slightly along its length. In this regard, squared contact sections can be placed on the edge of the rib, while round shaped contact areas are undesirable due to significant deformation of the edges of the ribs and the base of the radiator as a result of uniform deformation of the metal around the perimeter of the round contact section of the welded joint. Round contact areas lead to significant deformation of the edges of the ribs and base and to the need for additional machining of the sides of the radiator.

In addition, the strength of the radiator fins in bending (shear) under the action of a breaking force perpendicular to the width of the rectangular working protrusion of the punch is higher than when using cylindrical working protrusions with rounded contact pads.

Thus, the rectangular contact areas (weld points) in the fin radiator provides a minimum distance between the ribs of the corrugation and increases the strength of the connection of the radiator elements. Plate punches with cylindrical working protrusions are preferably applicable in the manufacture of radiators used for cooling electronic devices of medium and low power.

At the same time, the use of plate punches for cold pressure welding of structural elements of the radiator is preferable when forming radiators of limited standard sizes. In this case, the manufacture of long radiators or radiators of a large base area, including those designed to accommodate several semiconductor power devices, is more effective than using roller punches for cold pressure welding of the base and heat sink surface (Fig. 2c).

For example, on an aluminum base with a thickness of 20 mm and an area of 1000x1000 mm2 by cold spot welding, an aluminum corrugated heat sink surface made, for example, of a tape 1.0 mm thick with a rib height of 70.0 mm, is installed over the entire area of the base. The length of the ribs of the corrugation corresponds to the length of the base. The ribs are made in steps of 5.0 mm.

To obtain this kind of aluminum (copper, copper-aluminum, etc.) radiators use punches in the form of rollers (disks) that move along the rectangular grooves of the corrugation. The rollers are mounted on a tooling shaft with the possibility of their rotation. The radiator base is fixed on the bottom plate of the stamp with the ability to move with a special pusher in the horizontal plane. After installing the radiator base, a corrugated heat sink surface is placed on it. When applying pressure to the press, the punches (rollers) enter the grooves of the corrugation and their working protrusions located around the circumference of the rollers are pressed into the corrugation metal and the base of the radiator. The movement of the press stops, but the details of the radiator remain compressed by the upsetting force of the press. After that, the pusher of the stamp begins to move the base of the radiator, under the action of a constant force upsetting the press. Roller punches rotate and roll in grooves of the corrugation along the entire length of the groove. After that, the upsetting force of the press stops and the radiator assembled in this way is removed from the stamp. Thus, it is possible to manufacture a radiator with unlimited dimensional ratios.

To improve the electrical and thermal contact between the power semiconductor device and the base of the aluminum radiator, additionally, from the side of the device to the base of the radiator, at the initial stage, a copper plate 10 (Fig. 4) with a thickness comparable to the thickness of the corrugated surface can be welded by cold spot welding, preferably 1.0-1.5 mm. In this case, reliable electrical and thermal contact is ensured between the copper base of the power semiconductor device case and the radiator base. The implementation of copper platinum with a thickness of more or less than the specified range reduces the effectiveness of its application by reducing heat dissipation, complicating the design and increasing its overall dimensions.

The radiator base may also be further provided with a round-shaped hole 11 (FIG. 3) for mounting a semiconductor device, preferably located in the center of the radiator base, which further enhances the heat sink effect.

Thus, the claimed solution of the radiator provides an increase in the efficiency of heat transfer and assembly of the radiator design, an increase in the area of the cooled surface while reducing heat conduction losses, with the possibility of connecting structural elements of unlimited sizes and made of homogeneous and heterogeneous materials, and also reduces the cost of its manufacture, improves the ecology of the process manufacturing, expands the technological capabilities of the use of radiators.

Claims (21)

1. A radiator for cooling electronic devices, comprising a base made of metal with a heat sink surface fixed to it, characterized in that the radiator is made of plastic non-ferrous metals, and the heat sink surface is corrugated, where the corrugations form vertically oriented fins inseparably connected to the base by cold welding pressure along the corners of the corrugation basins adjacent to it, forming grooves between the ribs. 2. The radiator according to claim 1, characterized in that the heat sink surface is made of sheet material with a thickness of not more than 1/10 of the thickness of the base. 3. The radiator according to claim 8, characterized in that the base is made with a thickness of not higher than 30 mm. 4. The radiator according to claim 1, characterized in that the heat sink surface is made of aluminum. 5. The radiator according to claim 1, characterized in that the heat sink surface is made of copper. 6. The radiator according to claim 1, characterized in that the base is made of copper. 7. The radiator according to claim 1, characterized in that the base is made of aluminum. 8. The radiator according to claim 1, characterized in that the base and heat sink surface are made of homogeneous materials with the same or comparable thermal conductivity. 9. The radiator according to claim 1, characterized in that the base and heat sink surface are made of materials with different thermal conductivity. 10. The radiator according to claim 1, characterized in that the corrugated vertices of the heat sink surface opposite the base are rounded. 11. The radiator according to claim 1, characterized in that the corrugation vertices of the heat sink surface, opposite the base, are made in a U-shape. 12. The radiator according to claim 1, characterized in that the corrugation vertices of the heat sink surface, opposite the base, are made in a figured shape. 13. The radiator according to claim 1, characterized in that the side walls of the corrugations are made vertically oriented perpendicular to the base. 14. The radiator according to claim 1, characterized in that the side walls of the corrugations are made at an angle to it with the formation of trapezoidal shapes of the corrugations. 15. The radiator according to claim 1, characterized in that the vertices of the corrugations of the corrugations adjacent to the base are flattened, and the sides of the corrugations are counter-inclined to form an angle at the vertices opposite to the base. 16. The radiator according to any one of paragraphs. 1-11, characterized in that the integral connection of the base with adjacent peaks of the corrugations of the heat-conducting surface is made longitudinal along the length of the corrugation. 17. The radiator according to claim 16, characterized in that the longitudinal connection is made in the form of contact sections distributed longitudinally along the length of the corrugation. 18. The radiator according to claim 17, characterized in that the contact areas are made rectangular in plan. 19. The radiator according to claim 16, characterized in that the base is further provided with an additional contact plate located on the base, the opposite base, provided with a heat sink surface. 20. The radiator according to claim 19, characterized in that the contact plate is made of copper. 21. The radiator according to claim 16, characterized in that the base may be further provided with an opening.

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