A ceramic substrate for a heat sink and its preparation process

Abstract

The present application provides a ceramic substrate for a heat sink and a preparation process thereof. The ceramic substrate for a heat sink includes a composite AlN-SiC ceramic base layer and a TiAlN coating deposited on the surface of the composite AlN-SiC ceramic base layer. A plurality of blind holes are provided inside the composite AlN-SiC ceramic base layer, and the blind holes are filled with metal W. By using the AlN-SiC material with high mechanical strength as the ceramic base layer and filling metal W inside it to form a rapid heat dissipation channel, and then depositing a TiAlN transition layer, the obtained ceramic substrate for a heat sink can have a strong bonding force with the metal layer and does not affect the mechanical strength and heat dissipation performance of the ceramic substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramics, and particularly relates to a ceramic substrate for heat sink and a preparation process thereof. Background Art

[0002] With the continuous increase of the power density of electronic devices, the performance requirements for ceramic substrates for heat sinks are also getting higher and higher. An ideal ceramic substrate should have excellent mechanical strength, good heat dissipation performance, and high bonding strength with the metal layer. However, the existing technologies face significant contradictions and challenges in achieving these performances.

[0003] Specifically, in order to apply the ceramic substrate to the heat sink field, it needs to have a high thermal conductivity to effectively conduct heat, and it needs to have a high mechanical strength for subsequent processing such as metal patterning. However, in related technologies, in order to maintain the mechanical strength of the material, a certain thermal conductivity usually needs to be sacrificed, which limits the heat dissipation ability of the ceramic substrate in high-power applications; in addition, the improvement of the bonding strength between the ceramic substrate and the metal layer is often accompanied by an increase in the pore defects inside the ceramic, which will lead to a decrease in the heat dissipation performance and mechanical strength of the ceramic substrate. In summary, there are irreconcilable contradictions in the existing technologies in improving the mechanical strength, heat dissipation performance, and bonding strength with the metal layer of the ceramic substrate.

[0004] Therefore, there is an urgent need for a new technical solution to balance these performances to meet the strict requirements of high-power electronic devices for ceramic substrates for heat sinks. Summary of the Invention

[0005] Aiming at the defects in the existing technologies, the present invention provides a ceramic substrate for heat sink and a preparation process thereof to solve the problem of how to improve the comprehensive performance of the ceramic substrate for heat sink.

[0006] To solve the above technical problems, the present application provides the following technical solutions.

[0007] In a first aspect, the present application provides a ceramic substrate for heat sink, including a composite AlN-SiC ceramic base layer, a TiAlN coating deposited on the surface of the composite AlN-SiC ceramic base layer. A plurality of blind holes are provided inside the composite AlN-SiC ceramic base layer, and the blind holes are filled with metal W.

[0008] Preferably, the thermal conductivity of metal W is greater than that of AlN-SiC.

[0009] Preferably, the thickness of the TiAlN coating is 100 - 300 nm.

[0010] In a second aspect, the present application provides a preparation method of a ceramic substrate for heat sink, including the following steps:

[0011] S1. Using AlN - SiC, sintering aids, binders, and organic solvents as raw materials, a composite AlN - SiC ceramic base layer is formed by tape casting.

[0012] S2. Using the laser drilling process, punching is performed on the composite AlN - SiC ceramic base layer to obtain a composite AlN - SiC ceramic base layer with blind holes.

[0013] S3. Filling the blind holes with metal W paste to obtain a composite substrate.

[0014] S4. In - situ depositing a TiAlN coating on the composite substrate to obtain a ceramic substrate for heat sink.

[0015] Preferably, in step S1, the sintering aids include one or more of yttrium oxide and yttrium fluoride; the binders include one or more of polyvinyl alcohol and polyvinylpyrrolidone; the organic solvents include one or more of ethanol, n - butanol, and triethyl phosphate.

[0016] Preferably, in step S1, the sintering temperature of the tape casting method is 1600 - 1700 °C.

[0017] Preferably, between step S2 and step S3, there is also a step of soaking the composite AlN - SiC ceramic base layer with blind holes in a phosphoric acid solution.

[0018] Preferably, in step S3, after filling the metal W paste, there is also a polishing step.

[0019] Preferably, in step S4, the step of in - situ depositing the TiAlN coating is: using trimethylaluminum, titanium tetrachloride, and ammonia as precursors, and using the thermal atomic layer deposition process to prepare a TiAlN coating on the composite substrate.

[0020] In a third aspect, the present application provides an application of a ceramic substrate for heat sink in a heat sink assembly.

[0021] Compared with the prior art, the present invention achieves the following technical effects: In the present application, by using a high - mechanical - strength AlN - SiC material as the ceramic base layer, filling metal W inside to form a fast heat - dissipation channel, and then depositing a TiAlN transition layer, the obtained ceramic substrate for heat sink has a strong bonding force with the metal layer, and the ceramic substrate has high mechanical strength and good heat - dissipation performance. Detailed embodiments

[0022] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] The present application provides a ceramic substrate for a heat sink, including a composite AlN-SiC ceramic base layer, a TiAlN coating deposited on the surface of the composite AlN-SiC ceramic base layer. A plurality of blind holes are provided inside the composite AlN-SiC ceramic base layer, and the blind holes are filled with metal W.

[0024] In the solution of the present application, using the AlN-SiC material as the ceramic base layer can not only make up for the defects of easy hydrolysis of AlN and low density of SiC, but also ensure that the ceramic base layer has the advantages of AlN and SiC, such as high thermal conductivity, high insulation, and high hardness. At the same time, since AlN and SiC have similar densities and thermal expansion coefficients, the ceramic base layer has a high density and good mechanical properties, providing a mechanical basis for subsequent drilling and filling, and overcoming the defects of reduced mechanical strength and cracking of the ceramic substrate caused by drilling and filling with metal W. In the present application, metal W is filled in the composite AlN-SiC ceramic base layer. On the one hand, metal W has higher thermal conductivity than the composite AlN-SiC ceramic base layer, which can form a fast heat dissipation channel and improve the heat dissipation performance of the ceramic substrate. On the other hand, after the TiAlN layer is oxidized, an oxide layer with lower thermal conductivity will be formed. By using W in close contact with the TiAlN layer, W can inhibit the phase transformation of TiO2, thereby improving the oxidation resistance of the TiAlN layer and avoiding the problem of reduced thermal conductivity caused by the oxidation of the TiAlN layer. In the present application, a transition layer of TiAlN layer is deposited on the composite AlN-SiC ceramic base layer filled with metal W. Since the difference in thermal expansion coefficients between the ceramic substrate and the subsequent metal cladding (such as a copper layer) is large, the TiAlN layer can reduce the interfacial stress between the ceramic substrate and the subsequent metal cladding (such as a copper layer) and improve the bonding strength between the ceramic substrate and the subsequent metal cladding (such as a copper layer), ultimately achieving a balance of the mechanical properties, thermal conductivity, and bonding ability with the metal layer of the ceramic substrate.

[0025] In some embodiments, the thermal conductivity of metal W is greater than that of AlN-SiC.

[0026] In the application, the thermal conductivity of metal W is usually 170-180 W / (m·K). In the present application, the thermal conductivity of AlN-SiC being less than that of metal W can achieve the formation of a heat dissipation channel. If the thermal conductivity of AlN-SiC is equivalent to or less than that of the metallized material W, the heat flux density distribution is relatively uniform, and it is not easy to form a heat dissipation channel, and the improvement effect of the heat dissipation performance is not obvious.

[0027] In this application, the preparation method of the AlN-SiC material is as follows: Take silicon powder, carbon black, and aluminum nitride and put them into a ball mill for ball milling. Screen to separate the ball material and obtain a uniformly mixed powder. Then put the mixed powder into a graphite crucible and perform vacuum sintering to obtain the AlN-SiC material.

[0028] In some embodiments, the blind hole distribution pattern is an array distribution. The diameter of the blind hole is 0.15 - 0.2 mm, the spacing between adjacent blind holes is 0.4 - 0.8 mm, the size of the ceramic substrate for the heat sink is (8 - 10) mm * (8 - 10) mm, the thickness of the ceramic substrate for the heat sink is 0.8 - 1.0 mm, and the depth of the blind hole is 0.5 - 0.7 mm.

[0029] In this embodiment, arranging the blind holes according to the array distribution pattern defined in this application can achieve a balance between heat dissipation and mechanical properties. If the pores are too dense, the mechanical properties are poor; if the pores are too loose, the heat dissipation performance is poor.

[0030] The thickness of the TiAlN coating is 100 - 300 nm.

[0031] In this embodiment, the TiAlN coating has excellent properties such as high hardness, high oxidation temperature, good hot hardness, strong adhesion, and small friction coefficient. When the thickness of the TiAlN coating is within the defined range, a balance between heat dissipation and mechanical properties can be achieved. If the TiAlN coating is too thick, it will lead to a reduction in the heat dissipation performance of the ceramic substrate; if the TiAlN coating is too thin, it will affect the bonding strength between the ceramic substrate and the subsequent metal cladding.

[0032] This application provides a preparation method for a ceramic substrate for a heat sink, including the following steps:

[0033] S1. Using AlN-SiC, sintering aids, binders, and organic solvents as raw materials, form a composite AlN-SiC ceramic base layer by tape casting.

[0034] S2. Use the laser drilling process to punch holes in the composite AlN-SiC ceramic base layer to obtain a composite AlN-SiC ceramic base layer with blind holes.

[0035] S3. Fill the blind holes with metal W paste to obtain a composite substrate.

[0036] S4. In-situ deposit a TiAlN coating on the composite substrate to obtain the ceramic substrate for the heat sink.

[0037] In the embodiments of this application, the ceramic substrate is obtained through tape casting - laser drilling - hole filling - in-situ deposition of the transition layer. The process flow is short, and the blind hole distribution, the type of filled metal, and the thickness of the transition layer are all controllable, which is beneficial to obtaining a ceramic substrate for the heat sink with good comprehensive performance.

[0038] In some embodiments, in step S1, the sintering aid includes one or more of yttrium oxide and yttrium fluoride; the binder includes one or more of polyvinyl alcohol and polyvinylpyrrolidone; the organic solvent includes one or more of ethanol, n-butanol, and triethyl phosphate.

[0039] In this embodiment, the sintering aid is beneficial to reducing the sintering temperature of the tape casting method, the binder is beneficial to improving the strength of the composite AlN-SiC ceramic substrate, and the organic solvent does not contain aldehydes, ketones, or aromatics and has good compatibility with the sintering aid and the adhesive.

[0040] In some embodiments, in step S1, the sintering temperature of the tape casting method is 1600 - 1700 °C.

[0041] In this embodiment, sintering and forming can be achieved at 1600 - 1700 °C. The low sintering temperature is beneficial to the stability of the composite AlN-SiC ceramic substrate, thereby improving the mechanical strength of the AlN-SiC ceramic substrate.

[0042] In some embodiments, between step S2 and step S3, the following step is further included: soaking the composite AlN-SiC ceramic substrate provided with blind holes in a phosphoric acid solution.

[0043] In this embodiment, since the present application uses laser drilling, and laser processing of the ceramic substrate will result in the situation of molten slag on the micropore surface and roughness inside the holes, which affects the filling of metal W, and at the same time, the interaction between the laser and AlN easily causes the precipitation of Al, making the originally insulating AlN become a semiconductor, affecting the insulation performance of the substrate. Therefore, in this embodiment, through phosphoric acid soaking, the removal of Al precipitated by laser processing of the AlN substrate can be achieved, ensuring the insulation of the substrate, and at the same time reducing the molten slag on the micropore surface and the roughness inside the holes of the ceramic substrate.

[0044] In some embodiments, in step S3, after filling the metal W paste, a polishing step is further included.

[0045] In this embodiment, first fill the metal W paste, then sinter and polish, and repeat 3 - 5 times. By repeating filling, sintering, and polishing, the metal paste at the through-hole orifice is filled completely and smoothly, which is more beneficial to the deposition of the TiAlN coating.

[0046] In some embodiments, in step S4, the step of in-situ depositing the TiAlN coating is as follows: using trimethylaluminum, titanium tetrachloride, and ammonia as precursors, and using the thermal atomic layer deposition process to prepare the TiAlN coating on the composite substrate.

[0047] In this embodiment, the specific steps for in-situ depositing the TiAlN coating are as follows: heat the composite substrate to 100 °C, adsorb titanium tetrachloride onto the surface of the composite substrate under a pressure of 50 Pa, then add trimethylaluminum, after fumigating for 60 s, then flush away the excess TMA with an inert gas, and then drop in ammonia water for reaction to form a TiAlN layer. The above steps constitute one in-situ deposition cycle, and repeating these steps can gradually increase the thickness of the thin film.

[0048] This application provides an application of a ceramic substrate for a heat sink in a heat sink assembly.

[0049] Source of raw materials:

[0050] Metal W powder: The CAS number is 7440-33-7, and the thermal conductivity is 174 W / (m·K).

[0051] AlN-SiC: Take 100 g of silicon powder, 120 g of carbon black, and 80 g of aluminum nitride and put them into a ball mill jar for ball milling. Screen to separate the ball material to obtain a uniformly mixed powder. Then put the mixed powder into a graphite crucible and conduct vacuum sintering at 1800 °C for 3 h to obtain the AlN-SiC material. The measured thermal conductivity of the AlN-SiC material is 52.7 W / (m·K).

[0052] Example 1

[0053] A ceramic substrate for a heat sink, comprising a composite AlN-SiC ceramic base layer, a TiAlN coating deposited on the surface of the composite AlN-SiC ceramic base layer. There are a plurality of blind holes inside the composite AlN-SiC ceramic base layer, and the blind holes are filled with metal W. Among them, the distribution pattern of the blind holes is an array distribution, the diameter of the blind holes is 0.2 mm, the spacing between adjacent blind holes is 0.4 mm, the size of the ceramic substrate for the heat sink is 8 mm * 8 mm, the thickness of the ceramic substrate for the heat sink is 1.0 mm, the depth of the blind holes is 0.7 mm, and the thickness of the TiAlN coating is 300 nm.

[0054] The preparation method of the ceramic substrate for the heat sink includes the following steps:

[0055] S1. Mix 100 g of AlN-SiC powder, 5 g of yttrium oxide, and 200 ml of n-butanol and ball mill them, then add 3 g of polyvinyl alcohol to obtain a slurry. Set the height of the front knife edge of the tape casting machine to 2.0 mm, the height of the rear knife edge to 1.5 mm, and the tape casting speed to 0.20 m / min. Pour the degassed slurry and let it move and dry inside the tape of the tape casting machine for 2 hours to obtain a green body with a thickness of 0.75 mm. Put the green body into a graphite hot pressing sintering furnace and conduct positive pressure sintering in a flowing nitrogen atmosphere. Set the N2 gas pressure to 20 KPa, the sintering temperature to 1600 °C, and the holding time to 5 hours to obtain the composite AlN-SiC ceramic base layer;

[0056] S2. Using the laser drilling process, punch holes in the composite AlN-SiC ceramic base layer to obtain a composite AlN-SiC ceramic base layer with blind holes. Among them, the distribution pattern of the blind holes is an array distribution, the diameter of the blind holes is 0.2 mm, the spacing between adjacent blind holes is 0.4 mm, the size of the ceramic substrate for the heat sink is 8 mm * 8 mm, the thickness of the ceramic substrate for the heat sink is 1.0 mm, and the depth of the blind holes is 0.7 mm. Then, immerse the composite AlN-SiC ceramic base layer with blind holes into 200 ml of phosphoric acid, soak for 1 h and take it out;

[0057] S3. Inject molten metal W slurry into the blind holes, sinter and polish at 1500 °C, and repeat the sintering-polishing step 3 times to obtain a composite substrate;

[0058] S4. Heat the composite substrate to 100 °C, and adsorb 1 g of titanium tetrachloride on the surface of the composite substrate under a pressure of 50 Pa. Then add 2 g of trimethylaluminum, fumigate for 60 s, then flush away the excess TMA with an inert gas, and then drop 5 ml of ammonia water for reaction to form a TiAlN layer with a thickness of 50 nm. Repeat the above steps 6 times, and the thickness of the TiAlN layer is 300 nm, thus obtaining the ceramic substrate for the heat sink.

[0059] Example 2

[0060] A ceramic substrate for a heat sink, comprising a composite AlN-SiC ceramic base layer and a TiAlN coating deposited on the surface of the composite AlN-SiC ceramic base layer. There are a plurality of blind holes inside the composite AlN-SiC ceramic base layer, and the blind holes are filled with metal W. Among them, the distribution pattern of the blind holes is an array distribution, the diameter of the blind holes is 0.15 mm, the spacing between adjacent blind holes is 0.8 mm, the size of the ceramic substrate for the heat sink is 8 mm * 8 mm, the thickness of the ceramic substrate for the heat sink is 1.0 mm, the depth of the blind holes is 0.7 mm, and the thickness of the TiAlN coating is 300 nm.

[0061] The preparation method of the ceramic substrate for the heat sink includes the following steps:

[0062] S1. Mix 100 g of AlN-SiC powder, 5 g of yttrium oxide, and 200 ml of n-butanol and ball mill them, then add 3 g of polyvinyl alcohol to obtain a slurry. Set the height of the front knife edge of the tape casting machine to 2.0 mm, the height of the rear knife edge to 1.5 mm, and the tape casting speed to 0.20 m / min. Pour the defoamed slurry and let it move and dry inside the tape casting machine film belt at a variable temperature for 2 hours to obtain a green body with a thickness of 0.75 mm. Put the green body into a graphite hot pressing sintering furnace, sinter under a positive pressure in a flowing nitrogen atmosphere, set the N2 gas pressure at 20 KPa, the sintering temperature at 1600 °C, and the holding time at 5 hours to obtain a composite AlN-SiC ceramic base layer;

[0063] S2. Using the laser drilling process, punch holes in the composite AlN-SiC ceramic base layer to obtain a composite AlN-SiC ceramic base layer with blind holes. Among them, the distribution pattern of the blind holes is an array distribution, the diameter of the blind holes is 0.2 mm, the spacing between adjacent blind holes is 0.8 mm, the size of the ceramic substrate for the heat sink is 8 mm * 8 mm, the thickness of the ceramic substrate for the heat sink is 1.0 mm, and the depth of the blind holes is 0.7 mm. Then, immerse the composite AlN-SiC ceramic base layer with blind holes into 200 ml of phosphoric acid, soak for 1 h and take it out;

[0064] S3. Inject molten metal W slurry into the blind holes, sinter and polish at 1500 °C, and repeat the sintering-polishing step 3 times to obtain a composite substrate;

[0065] S4. Heat the composite substrate to 100 °C, and adsorb 1 g of titanium tetrachloride on the surface of the composite substrate under a pressure of 50 Pa. Then add 2 g of trimethylaluminum, fumigate for 60 s, then flush away the excess TMA with an inert gas, and then drop 5 ml of ammonia water for reaction to form a TiAlN layer with a thickness of 50 nm. Repeat the above steps 6 times, and the thickness of the TiAlN layer is 300 nm, that is, the ceramic substrate for the heat sink is obtained.

[0066] Example 3

[0067] A ceramic substrate for a heat sink, comprising a composite AlN-SiC ceramic base layer and a TiAlN coating deposited on the surface of the composite AlN-SiC ceramic base layer. There are multiple blind holes inside the composite AlN-SiC ceramic base layer, and the blind holes are filled with metal W. Among them, the distribution pattern of the blind holes is an array distribution, the diameter of the blind holes is 0.2 mm, the spacing between adjacent blind holes is 0.3 mm, the size of the ceramic substrate for the heat sink is 8 mm * 8 mm, the thickness of the ceramic substrate for the heat sink is 1.0 mm, the depth of the blind holes is 0.7 mm, and the thickness of the TiAlN coating is 300 nm.

[0068] The preparation method of the ceramic substrate for the heat sink includes the following steps:

[0069] S1. Mix 100 g of AlN-SiC powder, 5 g of yttrium oxide, and 200 ml of n-butanol and ball mill them, then add 3 g of polyvinyl alcohol to obtain a slurry. Set the height of the front knife edge of the casting machine to 2.0 mm, the height of the rear knife edge to 1.5 mm, and the casting speed to 0.20 m / min. Pour the defoamed slurry into it and let it move and dry inside the casting machine film belt at a variable temperature for 2 hours to obtain a green body with a thickness of 0.75 mm. Put the green body into a graphite hot pressing sintering furnace, sinter under a positive pressure in a flowing nitrogen atmosphere, set the N2 gas pressure at 20 KPa, the sintering temperature at 1600 °C, and the holding time at 5 hours to obtain a composite AlN-SiC ceramic base layer;

[0070] S2. Use the laser drilling process to punch holes in the composite AlN-SiC ceramic base layer to obtain a composite AlN-SiC ceramic base layer with blind holes. Among them, the distribution pattern of the blind holes is an array distribution, the diameter of the blind holes is 0.3 mm, the spacing between adjacent blind holes is 0.8 mm, the size of the ceramic substrate for the heat sink is 8 mm * 8 mm, the thickness of the ceramic substrate for the heat sink is 1.0 mm, and the depth of the blind holes is 0.7 mm. Then, immerse the composite AlN-SiC ceramic base layer with blind holes into 200 ml of phosphoric acid, soak for 1 h and take it out;

[0071] S3. Inject molten metal W slurry into the blind holes, sinter and polish at 1500 °C, and repeat the sintering-polishing step 3 times to obtain a composite substrate;

[0072] S4. Heat the composite substrate to 100 °C, and adsorb 1 g of titanium tetrachloride on the surface of the composite substrate under a pressure of 50 Pa. Then add 2 g of trimethylaluminum, fumigate for 60 s, then flush away the excess TMA with an inert gas, and then drop 5 ml of ammonia water for reaction to form a TiAlN layer with a thickness of 50 nm. Repeat the above steps 6 times, and the thickness of the TiAlN layer is 300 nm, that is, the ceramic substrate for the heat sink is obtained.

[0073] Example 4

[0074] A ceramic substrate for a heat sink, comprising a composite AlN-SiC ceramic base layer and a TiAlN coating deposited on the surface of the composite AlN-SiC ceramic base layer. There are a plurality of blind holes inside the composite AlN-SiC ceramic base layer, and the blind holes are filled with metal W. Among them, the distribution pattern of the blind holes is an array distribution, the diameter of the blind holes is 0.2 mm, the spacing between adjacent blind holes is 0.4 mm, the size of the ceramic substrate for the heat sink is 8 mm * 8 mm, the thickness of the ceramic substrate for the heat sink is 1.0 mm, the depth of the blind holes is 0.7 mm, and the thickness of the TiAlN coating is 50 nm.

[0075] The preparation method of the ceramic substrate for the heat sink includes the following steps:

[0076] S1. Mix 100 g of AlN-SiC powder, 5 g of yttrium fluoride, and 300 ml of ethanol and ball-mill them, then add 3 g of polyvinyl alcohol to obtain a slurry. Set the height of the front knife edge of the tape casting machine to 2.0 mm, the height of the rear knife edge to 1.5 mm, and the tape casting speed to 0.20 m / min. Pour the defoamed slurry into it and let it move and dry at a variable temperature on the tape of the tape casting machine for 2 hours to obtain a green body with a thickness of 0.75 mm. Put the green body into a graphite hot pressing sintering furnace, sinter under a positive pressure of a flowing nitrogen atmosphere, set the N2 gas pressure at 20 KPa, the sintering temperature at 1650 °C, and the holding time at 5 hours to obtain a composite AlN-SiC ceramic base layer;

[0077] S2. Using the laser drilling process, punch holes in the composite AlN-SiC ceramic base layer to obtain a composite AlN-SiC ceramic base layer with blind holes. Among them, the distribution pattern of the blind holes is an array distribution, the diameter of the blind holes is 0.15 mm, the spacing between adjacent blind holes is 0.4 mm, the size of the ceramic substrate for the heat sink is 8 mm * 8 mm, the thickness of the ceramic substrate for the heat sink is 1.0 mm, and the depth of the blind holes is 0.7 mm. Then, immerse the composite AlN-SiC ceramic base layer with blind holes in 200 ml of phosphoric acid, soak for 1 h and take it out;

[0078] S3. Inject molten metal W slurry into the blind holes, sinter and polish at 1500 °C, and repeat the sintering-polishing step 3 times to obtain a composite substrate;

[0079] S4. Heat the composite substrate to 100 °C, and adsorb 1 g of titanium tetrachloride on the surface of the composite substrate under a pressure of 50 Pa. Then add 2 g of trimethylaluminum, fumigate for 60 s, and then flush away the excess TMA with an inert gas, and then drop 5 ml of ammonia water for reaction to form a TiAlN layer with a thickness of 50 nm, that is, the ceramic substrate for the heat sink is obtained.

[0080] Comparative Example 1

[0081] A ceramic substrate for a heat sink, other contents are the same as those in Example 1, the difference is that it does not include blind holes.

[0082] Comparative Example 2

[0083] A ceramic substrate for a heat sink, other contents are the same as those in Example 1, the difference is that the blind holes are filled with titanium (CAS No. 7440-32-6) with a thermal conductivity of 22 W / (m·K).

[0084] Comparative Example 3

[0085] A ceramic substrate for a heat sink, other contents are the same as those in Example 1, the difference is that AlN-SiC is replaced by AlN.

[0086] Comparative Example 4

[0087] A ceramic substrate for a heat sink, other contents are the same as those in Example 1, the difference is that it does not include the TiAlN layer.

[0088] Comparative Example 5

[0089] A ceramic substrate for a heat sink, other contents are the same as those in Example 1, the difference is that the TiAlN layer is replaced by a Ti layer.

[0090] Testing and Evaluation

[0091] The mechanical properties, thermal conductivity and bonding ability with the Cu layer of the ceramic substrate for heat sink obtained in the test examples and comparative examples were evaluated, wherein the thermal conductivity was evaluated by testing the thermal resistance according to GB / T 10294-2008, the mechanical properties were evaluated by testing the strength of the ceramic substrate according to GB / T 4740-2024, and the bonding ability with the Cu layer was tested according to GB / T 39685-2020, and the results are shown in Table 1. The lower the thermal resistance, the better the heat dissipation performance.

[0092] Table 1 Performance test results

[0093]

[0094] It can be seen from the data in Table 1 that compared with Example 1, Comparative Example 1 has no blind holes, its thermal resistance increases significantly, the heat dissipation performance decreases, and the compressive strength does not change much; compared with Example 1, the metal filled in the blind hole of Comparative Example 2 is different, and the thermal conductivity of titanium is less than that of AlN-SiC, the thermal resistance increases, and Comparative Example 2 fails to achieve the improvement of the heat dissipation performance of the ceramic substrate; compared with Example 1, Comparative Example 3 replaces AlN-SiC with AlN, and the thermal conductivity of AlN is higher than that of AlN-SiC, but the overall thermal resistance of the ceramic substrate of Comparative Example 3 increases instead. The reason is that the thermal conductivity of the W metal in the hole is not much different from that of AlN, and a fast heat diffusion channel cannot be formed. At the same time, due to the replacement of AlN-SiC with AlN, the mechanical strength of the material is also greatly reduced; compared with Example 1, Comparative Examples 4 and 5 replace the TiAlN layer, which causes a significant reduction in the bonding force and mechanical strength of the ceramic substrate and the metal layer, while the thermal resistance does not change much.

[0095] From the comparison of Examples 1-3, it can be seen that the density of blind holes affects thermal resistance and compressive strength, and the density of blind holes within the specified range of the present application is more conducive to improving both thermal resistance and compressive strength. From the comparison of Example 1 and Example 4, it can be seen that if the TiAlN layer is too thin, the bonding force and mechanical strength between the ceramic substrate and the metal layer will be greatly reduced.

[0096] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A ceramic substrate for a heat sink, characterized in that: It comprises a composite AlN-SiC ceramic base layer and a TiAlN coating deposited on the surface of the composite AlN-SiC ceramic base layer. The composite AlN-SiC ceramic base layer is provided with a plurality of blind holes, and the blind holes are filled with metal W. The thermal conductivity of the metal W is greater than the thermal conductivity of the AlN-SiC. The blind holes are distributed in an array, the diameter of the blind holes is 0.15-0.2 mm, the spacing between adjacent blind holes is 0.4-0.8 mm, the thickness of the ceramic substrate for the heat sink is 0.8-1.0 mm, and the depth of the blind holes is 0.5-0.7 mm.

2. The heat sink ceramic substrate according to claim 1, characterized in that: The thickness of the TiAlN coating is 100-300 nm.

3. A method for preparing a ceramic substrate for a heat sink according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Using AlN-SiC, a sintering aid, a binder, and an organic solvent as raw materials, a composite AlN-SiC ceramic substrate is obtained by tape casting; S2. Using a laser drilling process, punching holes on the composite AlN-SiC ceramic substrate to obtain a composite AlN-SiC ceramic substrate having a blind hole; S3. Filling the blind hole with metal W slurry to obtain a composite substrate; S4. In-situ depositing a TiAlN coating on the composite substrate to obtain the ceramic substrate for the heat sink.

4. The method for preparing a ceramic substrate for a heat sink according to claim 3, characterized in that: In step S1, the sintering aid includes one or more of yttrium oxide and yttrium fluoride; the binder includes one or more of polyvinyl alcohol and polyvinyl pyrrolidone; and the organic solvent includes one or more of ethanol, n-butanol, and triethyl phosphate.

5. The method for preparing a ceramic substrate for a heat sink according to claim 3, characterized in that: In step S1, the sintering temperature of the tape casting method is 1600-1700°C.

6. The method for preparing a ceramic substrate for a heat sink according to claim 3, characterized in that: Between step S2 and step S3, the method further includes the step of soaking the composite AlN-SiC ceramic substrate provided with the blind holes in a phosphoric acid solution.

7. The method for preparing a ceramic substrate for a heat sink according to claim 3, characterized in that: In step S3, after filling the metal W slurry, a polishing step is also included.

8. The method for preparing a ceramic substrate for a heat sink according to claim 3, characterized in that: In the step S4, the step of in-situ depositing the TiAlN coating is: using trimethylaluminum, titanium tetrachloride and ammonia as precursors, and utilizing a thermal atomic layer deposition process to prepare the TiAlN coating on the composite substrate.

9. Use of the ceramic substrate for a heat sink according to any one of claims 1 to 2 in a heat sink assembly.

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