Ceramic-based heat sink and manufacturing method thereof

Abstract

The present invention relates to the field of heat dissipation technology of integrated electronic devices, and more specifically to a ceramic-based heat spreader and a manufacturing method thereof. The heat spreader includes a ceramic evaporation end, a metal condensation end and a liquid-filled tube. Microcolumns are distributed on the evaporation end and are evenly separated in the circumferential direction by a channel structure, and there are microcolumn channels with larger size and spacing than the microcolumns on the condensation end. During manufacturing, the wick structure on the ceramic material of the evaporation end can be processed by laser ablation, and the wick structure on the condensation end can be obtained by micro-milling. Finally, the evaporation end, the condensation end, and the liquid-filled tube are sealed together, and then the heat spreader can be processed through vacuuming, infusion, sealing and other processes. The evaporation end of the heat spreader has a gradient microcolumn structure, which can provide a good capillary force to drive the working fluid to quickly reflux. The evaporation end allows the chip to be directly arranged on it, eliminating the insulating layer in the middle. Therefore, the heat spreader has a smaller thermal resistance and can solve the heat dissipation problem under high power.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation of integrated electronic devices, and more particularly to a ceramic-based heat spreader and a manufacturing method thereof. Background Art

[0002] As electronic / optoelectronic chips continue to develop towards complexity, miniaturization and integration, their heat flux density continues to increase, bringing severe challenges to heat dissipation. The heat spreader is a highly efficient phase change heat transfer device that has a heat transfer performance that is dozens or even hundreds of times better than traditional copper-aluminum radiators, and does not require external pumping, making it an ideal choice for solving electronic / optoelectronic heat dissipation problems.

[0003] At present, the evaporation end and condensation end of the heat spreader are welded together by two copper or aluminum metal cover plates. However, the thermal expansion coefficient of copper or aluminum does not match the thermal expansion coefficient of the electronic / photoelectric chip, which causes the chip of the electronic / photoelectric device to easily fall off from the surface of the metal substrate during use, greatly reducing the service life and working reliability of the electronic / photoelectric device. In addition, an insulating layer must be set when the metal-based flat heat pipe is packaged with the electronic / photoelectric device. Its thermal conductivity is low, which significantly increases the total heat transfer thermal resistance and greatly reduces the heat dissipation effect of the electronic / photoelectric device. On the other hand, due to the poor heat resistance of the insulating layer, it cannot withstand high-temperature welding, which significantly affects the implementation of the packaging process and greatly limits the optimization of the packaging structure. Summary of the invention

[0004] The present invention provides a ceramic-based vapor chamber and a manufacturing method thereof, aiming to overcome the problem of large thermal resistance when metal is used as the vapor chamber substrate.

[0005] The above purpose is achieved through the following technical solutions:

[0006] A ceramic-based heat spreader includes an evaporation end, micro-columns distributed on the upper end of the evaporation end, and a condensation end fixedly connected to the upper end of the evaporation end. The evaporation end and the condensation end are sealed to form a cavity. Micro-column channels connected to the cavity and having a diameter larger than the micro-columns are distributed on the condensation end. After the evaporation end and the condensation end are coupled, a through hole connected to the cavity is formed. It is characterized in that a heat source area and a groove connected to the heat source area are provided at the center of the upper end of the evaporation end. The groove is meshed and includes an annular groove surrounding the heat source area, and a straight groove connected to the annular groove and the heat source area.

[0007] The evaporation end is made of silicon carbide or aluminum nitride ceramics.

[0008] The condensation end is aluminum or copper.

[0009] The inner end surfaces of the evaporation end and the condensation end are provided with concave cavities.

[0010] The microcolumn has a diameter of 0.3-0.4 mm and a height of 0.6-0.8 mm.

[0011] When the upper end of the micro-columns at the evaporation end is away from the central area, the spacing between the micro-columns gradually increases, and the spacing between each micro-column is 0.15-0.3 mm.

[0012] The width of the annular groove is 0.4-0.5 mm, and the width of the straight groove is 0.6-0.9 mm.

[0013] The angles of the straight channels are the same, 30°-50°

[0014] The method for preparing the above-mentioned ceramic-based vapor chamber comprises the following steps:

[0015] S1. Processing the micro-columns, the grooves and the heat source area on the surface of the evaporation end by laser ablation, with a laser power of 25-30W, a laser frequency of 20kHz, a scanning speed of 350-400mm / s and a scanning number of 10-20 times;

[0016] S2. Through micro-milling, a cavity and a micro-column channel are machined on the condensation end. The micro-milling spindle speed is 15000-16000r / min, the feed rate is 100-130mm / min, and the back cutting depth is 150-200um;

[0017] S3, using alkaline solution electroplating to perform super-hydrophobic treatment on the condensation end;

[0018] S4, buckle the evaporation end and the condensation end to form a cavity and add a liquid filling pipe between the evaporation end and the condensation end, and seal the four sides thereof by welding to form a heat diffusion plate;

[0019] S5. The cavity is evacuated through the liquid filling tube, and then the working medium is poured into the cavity. Finally, the end of the liquid filling tube close to the heat spreader is sealed.

[0020] Beneficial effects of a ceramic-based heat sink and a manufacturing method thereof:

[0021] 1) The ceramic-based heat spreader of the present invention fully utilizes the high temperature uniformity and efficient heat dissipation performance of the heat spreader's phase change heat transfer, and also utilizes the high thermal conductivity, insulation, and thermal expansion coefficient of ceramics that matches the electronic / optoelectronic chip, thereby avoiding the use of an insulating layer, significantly reducing the system's thermal resistance, improving heat dissipation efficiency, and greatly reducing the thermal stress between the packaging substrate and the electronic / optoelectronic chip.

[0022] 2) The gradient microcolumn wick structure of the ceramic-based heat spreader of the present invention can provide good capillary force, driving the working fluid to quickly flow back from the edge of the evaporation end to the central heat source area, thereby promoting evaporation-condensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 An exploded view of a ceramic-based vapor chamber;

[0024] Figure 2 It is a schematic diagram of the structure of the evaporation end of the heat spreader;

[0025] Figure 3 Schematic diagram of the micro-column channel structure at the condensation end of the vapor chamber;

[0026] Figure 4 It is a structural schematic diagram of the condensation end and the heat dissipation fins;

[0027] Figure 5 is a cross-sectional view of the heat spreader along the diameter direction;

[0028] Figure 6 The present invention is a flow chart of the preparation method of a ceramic-based heat spreader. DETAILED DESCRIPTION

[0029] like Figure 1-4 As shown, a ceramic-based vapor chamber comprises a ceramic-based evaporation end 1, and a condensation end 2 installed on the upper end of the evaporation end 1, and the connection between the two is sealed to form a vapor chamber; for ease of description, the area between the evaporation end 1 and the condensation end 2 is the inner side, and the opposite side is the outer side. A concave cavity is provided at the inner end of one of the evaporation end 1 and the condensation end 2, or a concave cavity is provided at the inner end of the evaporation end 1 and the inner end of the condensation end 2, so that a cavity is formed on the inner side of the evaporation end 1 and the condensation end 2;

[0030] The evaporation end 1 is preferably made of silicon carbide or aluminum nitride ceramics, the condensation end 2 is preferably made of aluminum or copper, and the working fluid is preferably deionized water.

[0031] In particular, a liquid wick structure, i.e. distributed micro-columns, is provided at the upper end of the evaporation end 1, wherein the micro-columns are located in the cavity, and the top ends of the micro-columns are in contact with the lower end surface of the condensation end 2;

[0032] The cavity can be connected to an external liquid supply device to realize vacuuming and filling of the cavity; specifically, after the evaporation end 1 and the condensation end 2 are coupled, there is a through hole connected to the cavity, wherein the liquid supply device includes a liquid filling pipe 3, the liquid filling pipe 3 passes through the through hole and is connected to the cavity, the connection between the liquid filling pipe 3 and the heat plate is sealed, and the working medium is introduced into the cavity by using the liquid filling pipe 3;

[0033] The sealing mentioned above is achieved by welding, more preferably by diffusion welding.

[0034] The evaporation end 1 is used to contact the heat source, where the heat is transferred to the entire vapor chamber. The working fluid inside the vapor chamber absorbs the heat and vaporizes into steam. The steam moves under the pressure difference, releases heat and liquefies at the condensation end 2, turns into liquid again, and condenses on the surface of the condensation end 2. The liquid gathers on the surface of the condensation end 2 and returns to the evaporation end through the microcolumns under the action of gravity, completing a cycle.

[0035] Since the evaporation end 1 can be directly integrated with the chip without an insulating layer, and the condensation end can also be directly integrated with the heat sink without interface materials, the overall thermal resistance is greatly reduced.

[0036] Furthermore, in order to accelerate the reflux of the working medium, a liquid wick structure is also provided on the condensation end 2, that is, a micro-column channel distributed on the condensation end 2 and connected to the cavity, the diameter of the micro-column channel is greater than the diameter of the micro-column, and the distance between the micro-column channels is also greater than the distance between the micro-columns;

[0037] The coordinated use of the micro-column channel and the micro-column can enable the working medium to reflux from the micro-column channel at the condensation end 2 to the micro-column at the evaporation end 1, thereby improving the reflux rate of the working medium.

[0038] Among them, the optimized microcolumn has a diameter of 0.3-0.4 mm and a height of 0.6-0.8 mm. When the microcolumns are at the upper end of the evaporation end 1 and away from the central area of ​​the evaporation end 1, the spacing between the microcolumns gradually increases, and the spacing between each microcolumn is 0.15-0.3 mm; the gradual increase in spacing can be a gradual increase in the spacing between microcolumns on a virtual straight line and microcolumns on an adjacent virtual straight line, or a gradual increase in the spacing between microcolumns on a virtual circular line and microcolumns on an adjacent virtual circular line.

[0039] Furthermore, in order to further improve the working fluid reflux capacity, a heat source area without micro-columns and a groove connected to the heat source area are provided at the center of the upper end of the evaporation end 1. There are no micro-columns on the groove, and the groove divides the micro-columns into 24-30 parts.

[0040] The gradient micro-column liquid wick structure of the micro-column and channel structure of the evaporation end 3 array in this solution increases the capillary performance of the liquid wick and improves the ability of the working medium to reflux. In general, compared with the existing heat spreader, its thermal resistance can be reduced to a large extent.

[0041] like Figure 2 As shown, the further optimized channel is meshed and includes an annular channel surrounding the heat source area and a straight channel connected to the annular channel and the heat source area, the width of the annular channel is 0.4-0.5mm, and the width of the straight channel is 0.6-0.9mm. This specification improves the heat dissipation effect while further increasing the working fluid reflux capacity.

[0042] According to the above range, the diameter of the evaporation end 1 is 55 mm, and the thickness is 1 mm. The diameter of the condensation end 2 is 55 mm, and the thickness is 3 mm.

[0043] In the above range, the most preferred parameters are: microcolumn diameter is 0.3mm, height is 0.6mm, spacing of the unchanged microcolumn spacing portion is 0.2mm, straight channel width is 0.8mm, annular channel width is 0.4mm, and channel depth is the same as microcolumn height.

[0044] Preferably, a chamfered surface is provided on the bottom of the microcolumnar channel on the condensation end 2 on one side close to the heat source area, so that when the liquid flows back down through the microcolumnar channel, it flows faster toward the heat source area.

[0045] like Figure 5 As shown, the metal condensation end 2 made of aluminum material can be made into an integrated form with the heat sink fins also made of aluminum or copper material to eliminate the interface thermal resistance of the connection, wherein the heat sink fins do not block the microcolumn channel.

[0046] The method for preparing the above ceramic-based heat sink is as follows: Figure 6 As shown, the following steps are included:

[0047] S1, the evaporation end 1 is processed on its surface by laser ablation to form the micro-column, the groove and the heat source area. The preferred laser processing parameters are: laser power 25-30w, laser frequency 20khz, scanning speed 350-400mm / s, scanning times 10 times;

[0048] S2 and the condensation end 2 are processed by micro-milling to form the cavity and micro-column channel thereon; the preferred micro-milling parameters are: spindle speed 15000-16000r / min, feed rate 100-130mm / min, back cutting depth 150-200um.

[0049] S3. Perform super-hydrophobic treatment on the condensation end 2 by alkaline solution electroplating to enhance the working fluid reflux.

[0050] S4, buckle the evaporation end 1 and the condensation end 2 to form a cavity and add a liquid filling tube 3 between the evaporation end 1 and the condensation end 2, and seal the four sides thereof to form a heat spreader by welding, preferably diffusion welding;

[0051] S5, evacuating the cavity through the liquid filling tube 3, then filling the working medium, and finally sealing the end of the liquid filling tube 3 close to the heat spreader.

Claims

1. A ceramic-based heat sink, comprising an evaporation end (1), micro-columns distributed on the upper end of the evaporation end (1), and a condensation end (2) fixedly connected to the upper end of the evaporation end (1), wherein the evaporation end (1) and the condensation end (2) are sealed to form a cavity, wherein the condensation end (2) is provided with micro-column channels connected to the cavity and having a diameter larger than that of the micro-columns, wherein the evaporation end (1) and the condensation end (2) are coupled to form a through hole connected to the cavity, wherein: A heat source region and a channel connected to the heat source region are provided at the center of the upper end of the evaporation end (1); the channel is mesh-shaped and includes an annular channel surrounding the heat source region and a straight channel connected to the annular channel and the heat source region; the characteristic is that when the micro-columns are away from the central region at the upper end of the evaporation end (1), the spacing between the micro-columns gradually increases.

2. The ceramic-based heat sink according to claim 1, wherein the evaporation end (1) is made of silicon carbide or aluminum nitride ceramic.

3. According to the ceramic-based heat sink according to claim 1, the condensation end (2) is aluminum or copper.

4. According to the ceramic-based heat sink according to claim 1, the inner end surfaces of the evaporation end (1) and the condensation end (2) are provided with concave cavities. 5 . The ceramic-based vapor chamber according to claim 1 , wherein the micro-columns have a diameter of 0.3-0.4 mm and a height of 0.6-0.8 mm.

6. According to the ceramic-based heat sink of claim 1, the gradually increasing spacing means that the spacing between micro-pillars on a virtual straight line and micro-pillars on adjacent virtual straight lines gradually increases, or the spacing between micro-pillars on a virtual circular line and micro-pillars on adjacent virtual circular lines gradually increases, and the center of the upper end of the evaporation end (1) is provided with a heat source area without micro-pillars, and a groove connected to the heat source area, there are no micro-pillars on the groove, the groove divides the micro-pillars into 24-30 parts, and the distance between each micro-pillar is 0.15-0.3mm. 7 . The ceramic-based heat sink according to claim 1 , wherein the annular groove has a width of 0.4-0.5 mm, and the linear groove has a width of 0.6-0.9 mm. 8 . The ceramic-based vapor chamber according to claim 1 , wherein the angles of the straight grooves are the same, which is 30°-50°.

9. A method for preparing a ceramic-based vapor chamber according to any one of claims 1 to 8, comprising the following steps: S1. The micro-columns, the grooves and the heat source area are processed on the surface of the evaporation end (1) by laser ablation, the laser power is 25-30W, the laser frequency is 20kHz, the scanning speed is 350-400mm / s, and the number of scans is 10-20 times; characterized in that when the micro-columns are away from the central area at the upper end of the evaporation end (1), the spacing between the micro-columns gradually increases; S2. Processing a cavity and a micro-column channel on the condensation end (2) by micro-milling, wherein the micro-milling spindle speed is 15000-16000 r / min, the feed rate is 100-130 mm / min, and the back cutting depth is 150-200 um; S3, using alkaline solution electroplating to perform super-hydrophobic treatment on the condensation end (2); S4, buckling the evaporation end (1) and the condensation end (2) to form a cavity and adding a liquid filling tube (3) between the evaporation end (1) and the condensation end (2), and sealing the four sides thereof by welding to form a heat diffusion plate; S5, evacuating the cavity through the liquid filling pipe (3), then injecting the working medium, and finally sealing the end of the liquid filling pipe (3) close to the heat spreader.

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