CN201039646Y - Channel type flat heat pipe heat spreader - Google Patents

Abstract

The utility model relates to a channel-type flat heat pipe heat spreader, which can be applied to heat dissipation devices of electronic devices and plays the role of uniform heat flow distribution. The utility model integrates the radial multi-channel structure and the bottom plate of the heat pipe, which strengthens the shape stability of the flat heat pipe and makes the flat heat pipe thinner. The zigzag-shaped end part of the channel connected to the boiling pool and the enhanced boiling effect of the channel can greatly improve the boiling heat transfer efficiency. The radial multi-channel design enhances the capillary force, so that the flat heat pipe can work under anti-gravity conditions. The protruding platform is in contact with the bottom surface of the upper cover plate, which not only plays a supporting role, but also strengthens the axial heat conduction of the flat heat pipe. The soaking plate is directly welded by the lower bottom plate and the upper cover plate, which is beneficial to the mass production of abrasive molding and has broad application prospects.

Description

Channel type flat heat pipe heat spreader

technical field

The utility model relates to a channel type flat heat pipe heat spreader, which can be applied to heat dissipation devices of electronic devices.

Background technique

The trend of miniaturization of electronic chips and high calorific value has led to the following notable features in the heat dissipation of electronic equipment: (1) The local heat flux density is very large, and the heat is easy to accumulate locally, resulting in excessive local temperature. (2) The distribution of heat flux is uneven, and high heat flux is usually limited to a small space. (3) During the start-up process of electronic equipment, it is easy to have an instantaneous power "surge" and burn out the electronic equipment. (4) The total heat flow that needs to be dissipated is not very large. Therefore, the key to cooling electronic equipment is how to reduce excessive local heat flux and prevent hot spots from causing equipment failure. In order to enhance the heat dissipation effect, a heat sink much larger than the volume of the chip is generally installed on the electronic chip. This can easily create hot spots on the chip surface. Moreover, the heat sink has a large thermal diffusion resistance, and the heat flux density distribution on the internal section is very uneven, and the heat dissipation effect of the heat sink is affected to a certain extent.

At present, the basic method to prevent hot spots due to heat accumulation inside the electronic chip is to attach a solid pure copper plate heat spreader with high thermal conductivity on the surface of the chip, and lead the heat generated inside the electronic chip to the radiator fin by heat conduction. On the fins, the heat is transferred into the airflow and taken away by the convection between the fins and the surrounding air (as shown in Figure 1). The solid pure copper plate heat spreader can evenly distribute the heat flow and eliminate hot spots to a certain extent. However, due to the limited thermal conductivity of copper, its heating effect is not very obvious. If a heat spreader is made of a superconducting thermal material such as diamond, its expensive price will make it difficult to popularize in practical applications. Therefore, a flat heat pipe type heat spreader is proposed.

The flat heat pipe heat spreader can maximize the uniformity of the heat flux density, because it utilizes the principle of efficient heat conduction of the heat pipe. Heat pipe is one of the most effective heat transfer elements known, it can transmit a large amount of heat through a small cross-sectional area for a long distance without external power. One end of the heat pipe is the evaporation section, and the other end is the condensation section. When one end of the heat pipe is heated, the liquid in the capillary wick evaporates, and the steam flows to the other end under a small pressure difference to release heat and condenses into a liquid, and the liquid flows back to the evaporation section along the porous material by capillary force. This cycle goes on and on, and heat is transferred from one end of the heat pipe to the other end. Traditional heat pipes are tubular, and can be divided into wire mesh heat pipes, channel heat pipes and sintered heat pipes according to the different capillary structures inside the heat pipes. Flat heat pipe heat spreader is a special-shaped heat pipe, its condensation section and evaporation section are replaced by two planes (evaporation surface and condensation surface), also known as flat heat pipe. In such a heat pipe, the dimension perpendicular to the direction of heat flow is large, but the dimension parallel to the direction of heat flow is small. The distance between the evaporation surface and the condensation surface is generally only a few millimeters. It is precisely because of the special shape of the flat heat pipe that it brings difficulties to the production and processing of the flat heat pipe and the layout of the internal capillary circuit: (1) The area of the evaporation surface and the condensation surface is large, and it is easy to vacuumize, sinter and weld. Deformation occurs in the heat pipe, and the shape of the heat pipe must be maintained by increasing the wall thickness and internal support. (2) In order to reduce the volume and weight of the radiator, the overall thickness of the heat spreader is generally 4mm. The inner cavity height is only 1 to 2mm. Such a narrow space brings difficulties to the layout of traditional capillary structure loops, and insufficient capillary pressure will cause the flat plate heat pipe to fail under anti-gravity conditions. (3) Copper itself has strong thermal conductivity. When the thickness of the flat heat pipe is 4m, compared with the copper plate of the same size, the advantage of the axial heat conduction ability of the phase change heat conduction is not very obvious. Its advantage lies in the radial heat conduction, that is to say, it has a good heat equalization effect.

Contents of the invention

The utility model aims to solve the defects that the wall surface is easily deformed, the capillary structure is difficult to form a loop, and the axial thermal resistance is relatively large during the processing of the flat heat pipe heat spreader. A channel-type flat heat pipe heat spreader is proposed. The utility model enables the heat spreader to have strong axial and radial heat conduction capabilities, and can work under anti-gravity conditions.

Refer to Fig. 2 for the technical scheme adopted by the utility model. The channel-type flat heat pipe heat spreader is welded by an upper cover plate 4 and a lower bottom plate 9 . A liquid filling hole 5 is left on the side of the upper cover plate 4 . A plurality of radial rectangular channels 8 are processed on the protruding platform of the lower bottom plate 9 . The depth of the channel 8 is the same as the height of the protruding platform, and the width is less than 0.5mm. The top of the protruding platform of the lower bottom plate 9 is in contact with the bottom of the upper cover plate 4 , and a liquid storage channel 10 is left between the side of the protruding platform and the side wall of the flat heat pipe. The channel 8 communicates with the boiling pool 7 in the protruding platform and the liquid storage channel 10 on the side. The position of the boiling pool 7 should correspond to the contact position between the electronic chip and the vapor chamber. When the heat pipe works, the working medium boils in the boiling pool 7 and the channel 8 which is closer to the heat source. The generated steam moves to the bottom of the upper cover plate 4 along the channel, and condenses to release heat. Under the action of capillary force in the channel, the condensed liquid returns to the vicinity of the boiling pool 7 and boils again to complete the phase change circulation process of the working fluid. If more working fluid is charged, the excess working fluid will be discharged into the liquid storage channel 10 by the driving force of the steam, so that the excess liquid will not hinder the circulation of the working fluid. When the heat dissipation power of the heat source is increased, the heat pipe needs more working fluid to maintain circulation, and the action of capillary force will suck the working fluid back into the channel from the liquid storage channel 10 again. Both the saw-tooth-shaped end of the channel 8 connected to the boiling pool 7 and the channel itself have the function of enhancing boiling, so the heat transfer efficiency of boiling can be greatly improved. The radial multi-channel design replaces the larger heat pipe steam chamber with a large number of channels, which enhances the capillary force and makes the phase change circulation of the working fluid smoother, so that the flat heat pipe can work under anti-gravity conditions . The integrated design of the capillary structure and the bottom plate of the heat pipe strengthens the shape stability of the flat heat pipe and makes the flat heat pipe thinner. The protruding platform is in contact with the bottom surface of the upper cover plate, which not only plays a supporting role, but also strengthens the axial heat conduction of the flat heat pipe. The vapor chamber is directly welded by the lower base plate and the upper cover plate, which saves the cumbersome processing processes such as sintering and arranging wire mesh, which is conducive to the implementation of mass production of abrasive molds and has broad application prospects.

The beneficial effects of the utility model:

1. The integrated design of the capillary structure and the bottom plate of the heat pipe strengthens the shape stability of the flat heat pipe and makes the flat heat pipe thinner.

2. The radial multi-channel design enhances the capillary force and makes the phase change circulation of the working fluid smoother, so that the flat heat pipe can work under anti-gravity conditions.

3. The protruding platform is in contact with the bottom surface of the upper cover, which not only plays a supporting role, but also strengthens the axial heat conduction of the flat heat pipe.

4. Both the zigzag-shaped end of the channel and the boiling pool and the channel itself have the function of enhancing boiling, so the performance of the heat spreader can be greatly improved.

5. The liquid storage channel can store excess working fluid so that it will not hinder the circulation of the working fluid.

Description of drawings

Figure 1: Application of the heat spreader;

Figure 2: Schematic diagram of the internal structure of the disc-shaped channel-type flat heat pipe heat spreader;

Figure 3: Schematic diagram of channel arrangement with stronger heat transfer effect;

Figure 4: Schematic diagram of the channel layout of a rectangular channel-type flat heat pipe heat spreader with the heat source located in the center;

Figure 5: Schematic diagram of the channel layout of the rectangular channel type flat heat pipe heat spreader with the heat source not located in the center;

The labels in Figures 1 to 5 are: 1. Fin heat sink, 2. Heat spreader, 3. Electronic chip, 4. Upper cover plate, 5. Filling hole, 6. Weld seam, 7. Boiling pool, 8 . Channel, 9. Lower bottom plate, 10. Liquid storage channel, 11. Annular channel, 12. Main channel, 13. Outer ring channel.

Detailed ways

In practical application, the appearance of the upper cover plate 4 and the lower bottom plate 9 of the present utility model is the same as that of the lower bottom surface of the finned heat sink 1, that is, the specific shape of the channel type flat heat pipe heat spreader should be the same as that of the finned heat sink 1. The shape of the bottom surface is the same. Specifically, it can be divided into two types: disc-shaped and rectangular. The position of the boiling pool 7 inside the flat heat pipe heat spreader should also correspond to the installation position of the electronic chip 3 . The size of the boiling pool 7 should be smaller than the size of the electronic chip 3 .

The embodiment of the utility model is specifically described below in conjunction with accompanying drawing:

When the electronic chip with an equivalent diameter of 20 mm is located in the center of the heat spreader, the specific structure of the disc-shaped channel-type flat heat pipe heat spreader can be seen in FIG. 2 . The wall thickness of the channel-type flat heat pipe heat spreader is 1 mm, and the height of the raised platform on the bottom plate 9 is 2 mm, so the thickness of the entire channel-type flat heat pipe heat spreader is only 4 mm. The cross-sectional diameter of the heat spreader is the same as that of the bottom surface of the finned heat sink 1 . An annular liquid storage channel 10 with a width of 1.5 mm is left between the side of the protruding platform on the lower bottom plate 9 and the wall of the heat pipe. In the center of the protruding platform, there is a boiling 7 pool with a diameter of 10mm. The slots 8 are 0.2mm wide, arranged radially and symmetrically, and the included angle between adjacent slots is 3°. In order to enhance the heat exchange effect, the channel arrangement form with stronger heat exchange effect can be adopted as shown in Fig. 3 . This design makes the channels protruding from the outer ring of the platform denser, and connects the outer ring channel 13 with the main body channel 12 through an annular channel 11, so that the flat heat pipe has a better heat uniformity effect.

The channel layout structure of the rectangular channel type flat heat pipe heat spreader is shown in Figure 4 and Figure 5 . Respectively, the electronic chip is located at the central point of the heat spreader and at the non-central point.

Claims (6)

1. Channel-type flat heat pipe heat spreader, including an upper cover plate (4), a lower base plate (9), and a liquid filling hole (5); wherein, the upper cover plate (4) is connected with the lower base plate (9) and filled with liquid The hole (5) is located on the side of the upper cover plate (4), and it is characterized in that: the lower base plate (9) is provided with a protruding platform integrated with the base plate, and a plurality of radial grooves are arranged on the protruding platform The channel (8) and the channel (8) are connected through the boiling pool (7) in the protruding platform, and the top of the protruding platform is in contact with the bottom of the upper cover plate (4). 2. The channel-type flat heat pipe heat spreader according to claim 1, characterized in that: there is a channel (8) between the side of the protruding platform and the side wall of the upper cover (4). The connected liquid storage channel (10). 3. The channel-type flat heat pipe heat spreader according to claim 2, characterized in that: the cross-section of the channel (8) is rectangular, and the depth of the channel (8) is the same as the height of the protruding platform , the width is less than 0.5mm. 4. The channel type flat heat pipe heat spreader according to claim 3, characterized in that: the position of the boiling pool (7) corresponds to the installation position of the electronic chip, and the size of the boiling pool (7) is smaller than that of the electronic chip. Dimensions of the chip (3). 5. The channel-type flat heat pipe heat spreader according to any one of claims 1 to 4, characterized in that: the outer ring channel (13) of the radial channel (8) is an encrypted channel , and connect the outer ring channel (13) with the main body channel (12) through an annular channel (11). 6. The channel-type flat heat pipe heat spreader according to claim 1 or 2, characterized in that: the shape of the upper cover plate (4) and the lower bottom plate (9) is consistent with that of the finned heat sink (1) The shape of the bottom surface is the same.

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