A heat dissipation substrate, its preparation method and application

Abstract

This invention discloses a heat dissipation substrate, its preparation method, and its application, belonging to the field of heat dissipation material technology. The heat dissipation substrate comprises a first copper layer, a first solder layer, a first TiC layer, a diamond sheet layer, a second TiC layer, a second solder layer, and a second copper layer stacked sequentially. A groove for placing a chip is provided on the surface of the first copper layer away from the diamond sheet layer. This heat dissipation substrate exhibits good thermal conductivity, high heat dissipation efficiency, low thermal stress between layers, and good bonding strength. Its preparation method is simple, cost-controllable, and suitable for industrial production. The automotive SiC chip packaging heat sink incorporating this heat dissipation substrate can efficiently dissipate heat under high heat flux density, high temperature, high pressure, and high frequency operating conditions, and can effectively avoid premature chip failure due to thermal stress and thermal fatigue, thereby ensuring high reliability and a long service life, meeting the needs of high-power, high-current-density new energy vehicles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat dissipation plates, in particular to a heat dissipation substrate and a preparation method and application thereof. BACKGROUND

[0002] The ceramic copper-clad heat dissipation substrate is a high-thermal-conductivity insulating heat sink material that is crucial in the modern high-power electronic and optoelectronic fields. In the preparation, aluminum nitride, aluminum oxide, silicon nitride and other ceramics are combined with copper foil by direct bonding, direct copper plating or active metal brazing to realize the metallization of the ceramic surface and make the ceramic have both electrical insulation and thermal conductivity of metal.

[0003] However, the SiC chip for new energy vehicles has extremely high heat flux density (100 W / cm 2 even higher), a high-temperature working environment (200℃~250℃ or even higher) and strict requirements for reliability and service life, which puts high requirements on the packaging and heat dissipation materials and structure thereof. The common ceramic copper-clad heat dissipation substrate is difficult to meet the performance requirements of the SiC chip for new energy vehicles, and the chip is prone to premature failure, thereby affecting the stability and service life of the vehicle.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The present application aims to provide a heat dissipation substrate and a preparation method and application thereof to solve or improve the above technical problems.

[0006] The present application can be achieved as follows:

[0007] In a first aspect, the present application provides a heat dissipation substrate, which comprises a first copper layer, a first brazing layer, a first TiC layer, a diamond sheet layer, a second TiC layer, a second brazing layer and a second copper layer which are sequentially stacked; and a recess for placing a chip is arranged on the side surface of the first copper layer away from the diamond sheet layer.

[0008] In an optional embodiment, the diamond sheet layer comprises at least one of the following features:

[0009] Feature 1: when the diamond sheet used in the diamond sheet layer is a single crystal diamond sheet, the thermal conductivity of the diamond sheet is greater than 2000 W / mk; when the diamond sheet used in the diamond sheet layer is a polycrystalline diamond sheet, the thermal conductivity of the diamond sheet is greater than 1200 W / mk;

[0010] Feature 2: the surface roughness of the diamond sheet used in the diamond sheet layer is 0.1 μm~0.8 μm;

[0011] Feature 3: the in-plane resistance of the diamond sheet used in the diamond sheet layer is not less than 500 mΩ;

[0012] Feature 4: The thickness of the diamond sheet used for the diamond sheet layer is 0.1mm-0.5mm.

[0013] In optional embodiments, the first TiC layer is obtained by reacting a first Ti-containing metal coating with the upper surface of the diamond sheet, the first Ti-containing metal coating having at least one of the following features:

[0014] Feature 5: The thickness of the first Ti-containing metal coating is 1μm-3μm;

[0015] Feature 6: The material of the first Ti-containing metal coating comprises at least one of titanium copper, titanium tungsten, titanium nickel, titanium chromium and titanium molybdenum;

[0016] And / or, the second TiC layer is obtained by reacting a second Ti-containing metal coating with the lower surface of the diamond sheet, the second Ti-containing metal coating having at least one of the following features:

[0017] Feature 7: The thickness of the second Ti-containing metal coating is 1μm-3μm;

[0018] Feature 8: The material of the second Ti-containing metal coating comprises at least one of titanium copper, titanium tungsten, titanium nickel, titanium chromium and titanium molybdenum.

[0019] In optional embodiments, the thickness of the first and second brazing layers is independently 0.02mm-0.1mm;

[0020] And / or, the solder used for the first and second brazing layers independently comprises at least one of silver copper titanium, silver copper chromium and copper titanium tin;

[0021] And / or, the thickness of the first and second copper layers is independently 0.1mm-1mm.

[0022] In optional embodiments, the outer surface of the first copper layer is sequentially provided with a first nickel layer and a first gold layer from inside to outside; wherein the thickness of the first nickel layer is 1μm-3μm, and the thickness of the first gold layer is 0.1μm-1μm;

[0023] And / or, the outer surface of the second copper layer is sequentially provided with a second nickel layer and a second gold layer from inside to outside; wherein the thickness of the second nickel layer is 1μm-3μm, and the thickness of the second gold layer is 0.1μm-1μm.

[0024] In optional embodiments, the heat dissipation substrate has at least one of the following features:

[0025] Feature 9: The thermal conductivity of the heat dissipation substrate is not less than 405W / mk;

[0026] Feature 10: The number of thermal shock times of the heat dissipation substrate is not less than 22 times.

[0027] In a second aspect, the present invention provides a method for preparing a heat dissipation substrate as described in any of the foregoing embodiments, comprising the following steps: sequentially stacking a first copper foil, a first solder, a modified diamond sheet, a second solder, and a second copper foil, followed by vacuum brazing to obtain a first intermediate heat dissipation substrate having a first copper layer, a first brazing layer, a first TiC layer, a diamond sheet layer, a second TiC layer, a second brazing layer, and a second copper layer; and providing a groove on the surface of the first copper layer of the first intermediate heat dissipation substrate;

[0028] The modified diamond sheet includes a diamond sheet layer, a first TiC layer on the upper surface of the diamond sheet, and a second TiC layer on the lower surface of the diamond sheet.

[0029] In an optional embodiment, the preparation of the modified diamond sheet includes: preparing a first Ti-containing metal layer and a second Ti-containing metal layer on the upper and lower surfaces of the diamond sheet, respectively, followed by vacuum annealing to form a first TiC layer on the upper surface of the diamond sheet and a second Ti-containing metal layer on the lower surface of the diamond sheet.

[0030] The vacuum annealing heat treatment temperature is 450℃~650℃, and the vacuum heat treatment time is 1h~3h.

[0031] In an optional embodiment, before preparing the first Ti-containing metal layer and the second Ti-containing metal layer, the diamond sheet is first subjected to plasma cleaning, ultrasonic cleaning and drying.

[0032] Among them, the power of plasma cleaning is 1100W~1300W, the gas flow rate of plasma cleaning is 70sccm~90sccm, the pressure of plasma cleaning is 45Pa~55Pa, the time of plasma cleaning is 4min~6min, and the radio frequency of plasma cleaning is 13MHz~14MHz.

[0033] The ultrasonic cleaning frequency is 35kHz~45kHz, and the ultrasonic cleaning power is 160W~200W.

[0034] In an optional embodiment, the first Ti-containing metal layer and the second Ti-containing metal layer are prepared by magnetron sputtering;

[0035] The conditions for magnetron sputtering include: DC sputtering power of 100W~160W, sputtering time of 1h~3h, target-substrate distance of 3cm~12cm, argon flow rate of 10sccm~30sccm, and vacuum level of less than 3×10⁻⁶. -3 Pa.

[0036] In an optional embodiment, before the stacking is performed, the first solder and the second solder are ultrasonically cleaned and dried.

[0037] And / or, before the stacking is performed, the first copper foil and the second copper foil are subjected to vacuum annealing, acid etching, ultrasonic cleaning and drying.

[0038] In an optional embodiment, vacuum brazing includes: at a vacuum level of 10... -1 Pa~10 -4 Under the conditions of Pa and brazing pressure of 0.1MPa~5MPa, the temperature is first raised to 620℃~680℃, held for 25min~35min, then the temperature is raised to 850℃~900℃, held for 15min~25min, then the temperature is lowered to 400℃~700℃, held for 25min~35min, and then cooled with the furnace.

[0039] In an optional implementation, the heating rate is 5°C / min to 12°C / min.

[0040] In an optional implementation, the cooling rate is 2°C / min to 4°C / min.

[0041] In an optional embodiment, the process of setting the groove includes: pressing, exposing, developing, plasma etching, and stripping the first intermediate heat dissipation plate.

[0042] In an optional embodiment, the method further includes: sequentially electroplating a first nickel layer and a first gold layer on the outer surface of the first copper layer having grooves, and sequentially electroplating a second nickel layer and a second gold layer on the outer surface of the second copper layer.

[0043] In an optional implementation, the method further includes: slitting the heat dissipation substrate and performing plasma cleaning;

[0044] The slitting process uses laser slitting, with a power of 18W~22W, a speed of 750mm / s~850mm / s, a frequency of 45KHz~55KHz, a pulse width of 8PS~12PS, and a voltage of 200V~240V.

[0045] Thirdly, the present invention provides an automotive SiC chip packaging heat sink, including a chip and a heat sink substrate of any of the foregoing embodiments, wherein the chip is soldered into a groove in the first copper layer of the heat sink substrate.

[0046] Fourthly, the present invention provides an automobile that includes a heat dissipation substrate of any of the foregoing embodiments or an on-board SiC chip package heat dissipation plate of the foregoing embodiments.

[0047] The beneficial effects of this invention include:

[0048] The heat dissipation substrate provided by this invention comprises a first copper layer, a first solder layer, a first TiC layer, a diamond sheet layer, a second TiC layer, a second solder layer, and a second copper layer stacked sequentially. A groove for placing a chip is provided on the surface of the first copper layer away from the diamond sheet layer. This heat dissipation substrate exhibits good thermal conductivity, high heat dissipation efficiency, low thermal stress between layers, and good bonding strength. Its fabrication method is simple, cost-controllable, and suitable for industrial production. The automotive SiC chip packaging heat sink incorporating this heat dissipation substrate can efficiently dissipate heat under high heat flux density, high temperature, high pressure, and high frequency operating conditions, and can effectively avoid premature chip failure due to thermal stress and thermal fatigue, thereby ensuring high reliability and a long service life, meeting the needs of high-power, high-current-density new energy vehicles. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the heat dissipation substrate in this invention;

[0051] Figure 2 This is a schematic diagram of the structure of the vehicle-mounted SiC chip packaging heat sink in this invention.

[0052] Icons: 100-Heat dissipation substrate; 11-First copper layer; 12-Second copper layer; 21-First solder layer; 22-Second solder layer; 31-First TiC layer; 32-Second TiC layer; 40-Diamond sheet layer; 50-Groove; 200-Chip; 300-Automotive SiC chip package heat dissipation plate. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0054] The following provides a detailed description of the heat dissipation substrate, its preparation method, and its applications provided by the present invention.

[0055] Please combine Figure 1 and Figure 2The present invention provides a heat dissipation substrate 100, which includes a first copper layer 11, a first solder layer 21, a first TiC layer 31, a diamond sheet layer 40, a second TiC layer 32, a second solder layer 22 and a second copper layer 12 stacked in sequence; a groove 50 for placing a chip 200 is provided on the side surface of the first copper layer 11 away from the diamond sheet layer 40.

[0056] In this invention, the diamond sheet used for the diamond layer 40 can be a single-crystal diamond sheet or a polycrystalline diamond sheet. When a single-crystal diamond sheet is used, the thermal conductivity of the diamond sheet is greater than 2000 W / mK; when a polycrystalline diamond sheet is used, the thermal conductivity of the diamond sheet is greater than 1200 W / mK.

[0057] This invention effectively solves the problem of low thermal conductivity in existing ceramic substrates by using diamond as the main material. Furthermore, diamond, with its extremely high in-plane thermal conductivity, rapidly diffuses the heat generated by the chip 200 within the first copper layer 11 longitudinally to the diamond sheet layer 40, avoiding localized heat accumulation. Simultaneously, the diamond sheet has high hardness, which can absorb the thermal expansion mismatch stress between the copper layer and the chip 200, reducing the risk of interface delamination and achieving high heat flux diffusion and high-frequency insulation.

[0058] In this invention, the surface roughness of the diamond sheet used in the diamond layer 40 is 0.1 μm to 0.8 μm, such as 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, or 0.8 μm, or other values ​​within the range of 0.1 μm to 0.8 μm. This roughness enables the diamond sheet to have a good bonding effect with the structural layer on its surface. In some optional embodiments, the roughness of the upper and lower surfaces of the diamond sheet can be the same or different, but both are controlled within the range of 0.1 μm to 0.8 μm.

[0059] In this invention, the diamond sheet used in the diamond sheet layer 40 has an in-plane resistivity of not less than 500mΩ and good insulation properties.

[0060] In this invention, the thickness of the diamond sheet used in the diamond sheet layer 40 can be 0.1mm to 0.5mm, such as 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm or 0.5mm, or other values ​​within the range of 0.1mm to 0.5mm.

[0061] If the diamond sheet thickness is less than 0.1mm, it is not conducive to effectively improving the overall thermal conductivity of the heat sink; if the diamond sheet thickness is greater than 0.5mm, it is not conducive to manufacturing products that meet customer size requirements. The reason is that the total thickness of automotive chip heat sinks is usually ≤1.0mm. If the diamond sheet is too thick, the thickness of the copper layer on both sides will be reduced. However, automotive chip heat sinks usually have high current load requirements, and copper that is too thin cannot meet the requirements of withstanding high current loads. Therefore, the diamond layer cannot be too thick.

[0062] In this invention, the first TiC layer 31 is obtained by reacting a first Ti-containing metal coating with the upper surface of a diamond sheet, and the second TiC layer 32 is obtained by reacting a second Ti-containing metal coating with the lower surface of a diamond sheet.

[0063] Specifically, the Ti in the first Ti-containing metal coating reacts with carbon atoms on the upper surface of the diamond sheet to form stable TiC, thereby ensuring good adhesion and bonding strength between the first TiC layer 31 and the upper surface of the diamond sheet layer 40, which is beneficial to improving the thermal shock resistance of the heat dissipation substrate 100. Similarly, the Ti in the second Ti-containing metal coating reacts with carbon atoms on the lower surface of the diamond sheet to form stable TiC, thereby ensuring good adhesion and bonding strength between the second TiC layer 32 and the lower surface of the diamond sheet layer 40, which is beneficial to improving the thermal shock resistance of the heat dissipation substrate 100.

[0064] In some alternative embodiments, the thickness of the first Ti-containing metal coating can be 1 μm to 3 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, or other values ​​within the range of 1 μm to 3 μm. Similarly, the thickness of the second Ti-containing metal coating can be 1 μm to 3 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, or other values ​​within the range of 1 μm to 3 μm.

[0065] If the thickness of the first Ti-containing metal coating or the second Ti-containing metal coating is less than 1 μm, the generated TiC is too small, making it difficult to effectively improve the interfacial bonding strength; if the thickness of the first Ti-containing metal coating or the second Ti-containing metal coating is greater than 3 μm, it is easy to cause excessive film-substrate stress, leading to problems such as coating peeling.

[0066] In some alternative embodiments, the material of the first Ti-containing metal coating may, by way of example but not limitation, include at least one of titanium copper, titanium tungsten, titanium nickel, titanium chromium, and titanium molybdenum. Similarly, the material of the second Ti-containing metal coating may, by way of example but not limitation, include at least one of titanium copper, titanium tungsten, titanium nickel, titanium chromium, and titanium molybdenum.

[0067] In this invention, the first brazing layer 21 and the second brazing layer 22 mainly function to firmly bond the copper layer and the diamond sheet together, forming a structure that has both the high thermal conductivity and high insulation of diamond and the thermal conductivity and solderability of metal, effectively connecting the high-power chip with the external heat dissipation system.

[0068] In some alternative embodiments, the thickness of the first brazing layer 21 and the second brazing layer 22 can each be independently 0.02 mm to 0.1 mm, such as 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm or 0.1 mm, or other values ​​within the range of 0.02 mm to 0.1 mm.

[0069] If the thickness of the first brazing layer 21 or the second brazing layer 22 is less than 0.02 mm, it is easy to cause insufficient bonding strength at the brazing interface; if the thickness of the first brazing layer 21 or the second brazing layer 22 is greater than 0.1 mm, the welding stress is too high, which can easily cause problems such as coating peeling.

[0070] In some alternative embodiments, the solder used for the first solder layer 21 and the second solder layer 22 may independently include at least one of silver-copper-titanium, silver-copper-chromium, and copper-titanium-tin.

[0071] In this invention, the thickness of the first copper layer 11 and the second copper layer 12 can be independently 0.1mm to 1mm, such as 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm, or other values ​​within the range of 0.1mm to 1mm.

[0072] If the thickness of the first copper layer 11 or the second copper layer 12 is less than 0.1mm, it cannot meet the needs of customers with high current loads; if the thickness of the first copper layer 11 or the second copper layer 12 is greater than 1mm, it will not only reduce the overall thermal conductivity, but also exceed the product thickness specification.

[0073] In some optional embodiments, the outer surface of the first copper layer 11 may be provided with a first nickel layer and a first gold layer from the inside to the outside, and the outer surface of the second copper layer 12 may be provided with a second nickel layer and a second gold layer from the inside to the outside.

[0074] By adding the aforementioned nickel and gold layers, the copper layer can be protected, preventing it from oxidizing upon contact with air and reducing its electrical and thermal conductivity.

[0075] In some alternative embodiments, the thickness of the first nickel layer can be 1 μm to 3 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, or other values ​​within the range of 1 μm to 3 μm. The thickness of the first gold layer can be 0.1 μm to 1 μm, such as 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, or 1 μm, or other values ​​within the range of 0.1 μm to 1 μm.

[0076] The thickness of the second nickel layer can be 1 μm to 3 μm, such as 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm, or other values ​​within the range of 1 μm to 3 μm. The thickness of the second gold layer can be 0.1 μm to 1 μm, such as 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, or 1 μm, or other values ​​within the range of 0.1 μm to 1 μm.

[0077] In some alternative implementations, the thermal conductivity of the heat dissipation substrate 100 is not less than 405 W / mk, such as 406 W / mk to 870 W / mk.

[0078] In some alternative implementations, the thermal shock cycle of the heat dissipation substrate 100 is not less than 22 times, such as 22 to 30 times.

[0079] Accordingly, the present invention also provides a method for preparing the above-mentioned heat dissipation substrate 100, which may include the following steps: stacking a first copper foil, a first solder, a modified diamond sheet, a second solder, and a second copper foil in sequence, and then performing vacuum brazing to obtain a first intermediate heat dissipation plate having a first copper layer 11, a first brazing layer 21, a first TiC layer 31, a diamond sheet layer 40, a second TiC layer 32, a second brazing layer 22, and a second copper layer 12; and providing a groove 50 on the surface of the first copper layer 11 of the first intermediate heat dissipation plate.

[0080] The modified diamond sheet mentioned above includes a diamond sheet layer 40, a first TiC layer 31 located on the upper surface of the diamond sheet, and a second TiC layer 32 located on the lower surface of the diamond sheet.

[0081] In some optional embodiments, the preparation of the modified diamond sheet includes: preparing a first Ti-containing metal layer and a second Ti-containing metal layer on the upper and lower surfaces of the diamond sheet, respectively, followed by vacuum annealing to form a first TiC layer 31 on the upper surface of the diamond sheet and a second Ti-containing metal layer 32 on the lower surface of the diamond sheet.

[0082] In some alternative embodiments, the diamond sheet is first subjected to plasma cleaning, ultrasonic cleaning, and drying before the preparation of the first Ti-containing metal layer and the second Ti-containing metal layer.

[0083] The plasma cleaning power can be 1100W~1300W (e.g., 1100W, 1150W, 1200W, 1250W or 1300W), the plasma cleaning gas flow rate can be 70sccm~90sccm (e.g., 70sccm, 75sccm, 80sccm, 85sccm or 90sccm), the plasma cleaning pressure can be 45Pa~55Pa (e.g., 45Pa, 50Pa or 55Pa), the plasma cleaning time can be 4min~6min (e.g., 4min, 5min or 6min), and the plasma cleaning radio frequency can be 13MHz~14MHz (e.g., 13MHz, 13.5MHz or 14MHz).

[0084] The plasma cleaning process described above can improve the surface energy, wettability, and adhesion of the diamond sheet, thereby increasing the bonding force between the first Ti-containing metal layer and the second Ti-containing metal layer and the diamond sheet. This, in turn, improves the bonding force between the first TiC layer 31, the diamond sheet layer 40, and the second TiC layer 32, preventing problems such as layer separation and detachment during thermal shock.

[0085] The ultrasonic cleaning frequency can be 35kHz~45kHz (e.g., 35kHz, 40kHz, or 45kHz), and the ultrasonic cleaning power can be 160W~200W (e.g., 160W, 180W, or 200W). The above ultrasonic cleaning process can be carried out at room temperature, specifically using acetone, ethanol, and pure water for 1min~3min respectively.

[0086] The plasma cleaning and ultrasonic cleaning methods described above can effectively remove impurities (including graphite, oil, etc.) from the surface of diamond sheets.

[0087] In some alternative implementations, the first Ti-containing metal layer and the second Ti-containing metal layer can be prepared by magnetron sputtering.

[0088] The conditions for magnetron sputtering may include: DC sputtering power of 100W~160W (e.g., 100W, 120W, 140W, or 160W), sputtering time of 1h~3h (e.g., 1h, 2h, or 3h), target-substrate distance of 3cm~12cm (e.g., 3cm, 5cm, 8cm, 10cm, or 12cm), argon flow rate of 10sccm~30sccm (e.g., 10sccm, 15sccm, 20sccm, 25sccm, or 30sccm), and vacuum level of less than 3×10⁻⁶. -3 Pa.

[0089] By performing magnetron sputtering coating under the above conditions in a magnetron sputtering coating machine, an atomically mixed and dense Ti-containing metal coating can be formed on the surface of the diamond sheet, which is beneficial to improving the interfacial adhesion and shear strength between the Ti-containing metal coating and the diamond sheet.

[0090] In some alternative embodiments, during the preparation of the modified diamond sheet, the temperature of the vacuum annealing heat treatment can be 450℃~650℃, such as 450℃, 500℃, 550℃, 600℃ or 650℃, or other values ​​within the range of 450℃~650℃.

[0091] The vacuum heat treatment time can be 1h to 3h, such as 1h, 1.5h, 2h, 2.5h or 3h, or other values ​​within the range of 1h to 3h.

[0092] The vacuum annealing heat treatment described above allows the Ti in the Ti-containing metal coating to react with the carbon atoms on the diamond sheet surface to form a stable TiC layer. At the same time, it can also remove the film substrate stress generated during the aforementioned magnetron sputtering coating process and enhance the adhesion between film layers.

[0093] In some optional embodiments, before the layering is performed, the first and second solders can be ultrasonically cleaned and dried. The ultrasonic cleaning frequency can be 35kHz to 45kHz (e.g., 35kHz, 40kHz, or 45kHz), and the ultrasonic cleaning power can be 160W to 200W (e.g., 160W, 180W, or 200W). The ultrasonic cleaning process can be performed at room temperature, specifically using acetone, ethanol, and pure water for 1 to 3 minutes respectively.

[0094] In some alternative embodiments, the first and second copper foils may be subjected to vacuum annealing, acid etching, ultrasonic cleaning, and drying before being stacked.

[0095] Both the first and second copper foils are made of oxygen-free copper foil.

[0096] The vacuum annealing heat treatment temperature for the first and second copper foils can be between 450℃ and 650℃, such as 450℃, 500℃, 550℃, 600℃, or 650℃, or other values ​​within the range of 450℃ to 650℃. The vacuum heat treatment time can be between 1 hour and 3 hours, such as 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours, or other values ​​within the range of 1 hour to 3 hours.

[0097] The purpose of acid etching of the first and second copper foils is mainly to remove oxides from the surface of the copper foils.

[0098] The ultrasonic cleaning of the first and second copper foils can be performed sequentially using ethanol and pure water.

[0099] In some alternative embodiments, vacuum brazing includes: at a vacuum level of 10... -1 Pa~10 -4 Pa (e.g., 10) -1 Pa, 10 -2 Pa, 10 -3 Pa or 10 -4 Under conditions of brazing pressure of 0.1MPa to 5MPa (e.g., 0.1MPa, 0.5MPa, 1MPa, 2MPa, 3MPa, 4MPa, or 5MPa), first raise the temperature to 620℃ to 680℃ (e.g., 620℃, 640℃, 660℃, or 680℃), hold at that temperature for 25min to 35min (e.g., 25min, 30min, or 35min), and then continue to raise the temperature to 850℃. Heat to 900℃ (e.g., 850℃, 880℃, or 900℃), hold for 15-25 minutes (e.g., 15 minutes, 20 minutes, or 25 minutes), then cool to 400℃-700℃ (e.g., 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, or 700℃), hold for 25-35 minutes (e.g., 25 minutes, 30 minutes, or 35 minutes), and then cool with the furnace.

[0100] It should be emphasized that the vacuum brazing process of the present invention specifically includes two stages of heating and two stages of cooling. The first stage of heating and holding primarily serves to uniformize the furnace temperature and ensure the achievement of vacuum. The second stage of heating and holding primarily serves to fully melt and extend the solder, strengthening the bond between the copper and diamond layers. The first stage of cooling and holding primarily serves to slowly lower the temperature and release welding thermal stress. The second stage of cooling primarily serves to lower the temperature to room temperature. In particular, if the furnace is cooled directly during the cooling process, it can easily lead to excessive welding thermal stress and delamination of the weld layer.

[0101] In some optional embodiments, the heating rate during the vacuum brazing process can be 5℃ / min to 12℃ / min, such as 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, or 12℃ / min, or other values ​​within the range of 5℃ / min to 12℃ / min. The cooling rate during the vacuum brazing process can be 2℃ / min to 4℃ / min, such as 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, or 4℃ / min.

[0102] After vacuum brazing is completed, the copper layer surface of the obtained first intermediate heat dissipation plate can be mechanically ground and polished.

[0103] In some alternative embodiments, the process of setting the groove 50 includes: pressing, exposing, developing, plasma etching, and stripping the first intermediate heat dissipation plate.

[0104] The lamination conditions include: using HMDS for adhesion enhancement, using positive photoresist, and laminating at 90℃~110℃ and 800rpm~1200rpm for 85s~95s.

[0105] Exposure conditions include: 280 mJ / cm on the exposure machine. 2 ~320mJ / cm 2 Exposure energy is used for exposure.

[0106] The development conditions include: using a 2%~2.5% tetramethylammonium hydroxide developer, spraying the photoresist for 8s~12s, letting it stand for 45s~55s, rinsing it thoroughly with deionized water, and baking it at 90℃~110℃ for 85s~95s to strengthen the photoresist.

[0107] The plasma etching conditions include: using Cl2 (45 sccm~55 sccm) and N2 (15 sccm~25 sccm), etching copper layer trenches at a chamber pressure of 8 mTorr~12 mTorr, a plasma power of 900 W~1100 W, a bias power of 180 W~220 W, and a temperature of 75℃~85℃.

[0108] The film removal process conditions include: using O2 plasma ashing to remove the dry film at a chamber pressure of 900mTorr~1100mTorr, a power of 1400W~1600W, and a processing temperature of 180℃~220℃, followed by wet cleaning to thoroughly remove organic matter.

[0109] In some optional embodiments, the method further includes: sequentially electroplating a first nickel layer and a first gold layer on the outer surface of the first copper layer 11 having the groove 50, and sequentially electroplating a second nickel layer and a second gold layer on the outer surface of the second copper layer 12.

[0110] Furthermore, it may also include: slitting and plasma cleaning of the heat dissipation substrate 100.

[0111] The slitting process employs laser slitting with a power of 18W~22W (e.g., 18W, 20W, or 22W), a slitting speed of 750mm / s~850mm / s (e.g., 750mm / s, 800mm / s, or 850mm / s), a slitting frequency of 45KHz~55KHz (e.g., 45KHz, 50KHz, or 55KHz), a slitting pulse width of 8PS~12PS (e.g., 8PS, 10PS, or 12PS), and a slitting voltage of 200V~240V (e.g., 200V, 220V, or 220V). The laser slitting power is controlled within the range of 18W~22W to prevent graphitization of the heat sink substrate 100.

[0112] The power of plasma cleaning can be 1100W~1300W (e.g., 1100W, 1150W, 1200W, 1250W or 1300W, etc.), the gas flow rate of plasma cleaning can be 70sccm~90sccm (e.g., 70sccm, 75sccm, 80sccm, 85sccm or 90sccm, etc.), the pressure of plasma cleaning can be 45Pa~55Pa (e.g., 45Pa, 50Pa or 55Pa, etc.), the time of plasma cleaning can be 4min~6min (e.g., 4min, 5min or 6min, etc.), and the radio frequency of plasma cleaning can be 13MHz~14MHz (e.g., 13MHz, 13.5MHz or 14MHz, etc.).

[0113] The plasma cleaning process described above can remove impurities and graphite generated during the slitting process.

[0114] In addition, the present invention also provides an automotive SiC chip package heat sink 300, which includes a chip 200 and the aforementioned heat sink substrate 100, wherein the chip 200 is soldered into a groove 50 of the first copper layer 11 in the heat sink substrate 100.

[0115] It should be emphasized that the vehicle-mounted chip 200 is usually directly mounted on the surface of the heat sink. However, this invention specifically provides a groove 50 in the first copper layer 11 and welds the chip 200 into the groove 50. This allows the bottom and sides of the chip 200 to be connected to the first copper layer 11, greatly increasing the heat dissipation area of ​​the chip 200. In addition, the brazing layer and TiC layer provided between the copper layer and the diamond sheet layer 40 ensure a stable bond between the copper layer and the diamond sheet layer 40. This allows the diamond sheet layer 40 to stably, quickly, and uniformly diffuse the heat generated by the chip 200 in the first copper layer 11 to the diamond sheet layer 40, avoiding heat accumulation.

[0116] In some alternative embodiments, the surface of the first copper layer 11 is provided with a plurality of grooves 50. The number, shape, size and distribution of the grooves 50 can be adjusted as needed, and will not be limited or described in detail here.

[0117] In some alternative embodiments, the soldering conditions may include: soldering the chip to a copper layer groove using nano-silver solder paste under an inert gas (N2) protection. The soldering temperature may be 280°C to 320°C, the soldering pressure may be 18MPa to 22MPa, and the holding time may be 2 min to 4 min.

[0118] The vehicle-mounted SiC chip package heat sink 300 can efficiently dissipate heat under high heat flux density, high temperature, high pressure and high frequency conditions, and has high reliability and long service life.

[0119] Accordingly, the present invention also provides an automobile that includes the above-described heat dissipation substrate 100 or the vehicle-mounted SiC chip package heat dissipation plate 300 of the aforementioned embodiments.

[0120] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0121] Example 1

[0122] This embodiment provides an on-board SiC chip packaged heat sink 300, the preparation method of which includes:

[0123] S1: Material preparation.

[0124] S1-1: Prepare the first copper foil and the second copper foil.

[0125] Vacuum annealing, acid etching, ultrasonic cleaning, and drying were performed on the first oxygen-free copper foil (0.5 mm thick) and the second oxygen-free copper foil (0.5 mm thick).

[0126] The vacuum annealing heat treatment was carried out at a temperature of 600℃ for 2 hours.

[0127] The acid etching process includes: acid etching the above oxygen-free copper foil for 30 seconds using a copper oxide cleaner to remove oxides and other impurities from the surface of the copper foil.

[0128] The ultrasonic cleaning was performed at a frequency of 40 kHz and a power of 180 W. The ultrasonic cleaning process was carried out at room temperature, with ethanol and pure water used for ultrasonic cleaning for 2 minutes each.

[0129] S1-2: Prepare the first solder and the second solder.

[0130] The first solder (0.05mm thick silver-copper-titanium solder) and the second solder (0.05mm thick silver-copper-titanium solder) were ultrasonically cleaned and dried. The ultrasonic cleaning frequency was 40kHz and the power was 180W. The ultrasonic cleaning process was carried out at room temperature, with acetone, ethanol, and pure water used sequentially for 2 minutes each.

[0131] S1-3: Prepare modified diamond sheets.

[0132] S1-3-1: A CVD single-crystal diamond wafer with a diameter of 50.8 mm and a thickness of 0.3 mm was selected. The roughness Ra of both sides of the diamond wafer was 0.5 μm, and the in-plane resistivity was 500 MΩ. The diamond wafer was subjected to plasma cleaning under the following conditions: power of 1200 W, gas flow rate of 80 sccm, pressure of 50 Pa, time of 5 min, and radio frequency of 13.56 MHz. Subsequently, it was ultrasonically cleaned sequentially at room temperature with acetone, ethanol, and pure water for 2 min each, with an ultrasonic frequency of 40 kHz and an ultrasonic power of 180 W, and then dried.

[0133] S1-3-2: Using magnetron sputtering, a first Ti-containing metal layer (including a 150 nm thick titanium layer and a 2000 nm thick copper layer) and a second Ti-containing metal layer (including a 150 nm thick titanium layer and a 2000 nm thick copper layer) are prepared on the upper and lower surfaces of the dried diamond sheet, respectively. Then, vacuum annealing is performed to obtain the first TiC layer 31 and the second TiC layer 32.

[0134] The magnetron sputtering process involved a power of 140W, a duration of 2 hours, a target-substrate distance of 10cm, an argon flow rate of 20sccm, and a vacuum level of less than 3×10⁻⁶. -3 Pa.

[0135] The vacuum annealing heat treatment was performed at a temperature of 550℃ for 1.5 hours.

[0136] S2: The first copper foil, the first solder, the modified diamond sheet, the second solder, and the second copper foil are stacked sequentially and then vacuum brazed to obtain a first intermediate heat dissipation plate having a first copper layer 11, a first brazing layer 21, a first TiC layer 31, a diamond sheet layer 40, a second TiC layer 32, a second brazing layer 22, and a second copper layer 12; the surface of the copper layer of the first intermediate heat dissipation plate is mechanically ground and polished to make its surface roughness 0.2μm.

[0137] The vacuum brazing process includes: at a vacuum level of 10... -3Under the conditions of Pa and brazing pressure of 0.5MPa, the temperature is first raised to 650℃ at a rate of 10℃ / min, held for 30min, then raised to 880℃ at a rate of 5℃ / min, held for 20min, then cooled to 500℃ at a rate of 3℃ / min, held for 30min, and then cooled with the furnace.

[0138] S3: A groove 50 is provided on the surface of the first copper layer 11 of the first intermediate heat dissipation plate.

[0139] The first intermediate heat dissipation plate is subjected to lamination, exposure, development, plasma dry etching, and film removal to form multiple grooves 50.

[0140] The lamination conditions include: using HMDS for adhesion enhancement, using positive photoresist, and laminating the film at 100°C and 1000 rpm for 90 seconds.

[0141] Exposure conditions include: 300 mJ / cm on the exposure machine. 2 Exposure energy is used for exposure.

[0142] The development conditions include: using a 2.38% tetramethylammonium hydroxide developer, spraying the photoresist for 10 seconds, letting it stand for 50 seconds, rinsing it thoroughly with deionized water, and baking it at 100°C for 90 seconds to strengthen the photoresist.

[0143] The plasma etching conditions included: using Cl2 (50 sccm) and N2 (20 sccm), etching copper trenches at a chamber pressure of 10 mTorr, a plasma power of 1000 W, a bias power of 200 W, and a temperature of 80 °C.

[0144] The film removal process conditions include: using O2 plasma ashing to remove the dry film at a chamber pressure of 1000 mTorr, a power of 1500 W, and a processing temperature of 200 °C, followed by wet cleaning to thoroughly remove organic matter.

[0145] Each groove 50 has a depth of 0.2mm, a width of 6mm, and a length of 6mm.

[0146] S4: A first nickel layer and a first gold layer are sequentially electroplated on the outer surface of the first copper layer 11 with groove 50, and a second nickel layer and a second gold layer are sequentially electroplated on the outer surface of the second copper layer 12 to obtain a heat dissipation substrate 100.

[0147] The thickness of the first nickel layer and the second nickel layer is 2 μm, and the thickness of the first gold layer and the second gold layer is 0.5 μm.

[0148] S5: The heat sink substrate 100 is slit and plasma cleaned.

[0149] The slitting process uses laser slitting with a power of 20W, a speed of 800mm / s, a frequency of 50KHz, a pulse width of 10PS, and a voltage of 220V.

[0150] The plasma cleaning conditions included: power of 1200W, gas flow rate of 80sccm, pressure of 50Pa, time of 5min, and radio frequency of 13.56MHz. Subsequently, the plasma was ultrasonically cleaned for 2min each with acetone, ethanol, and pure water at room temperature, with an ultrasonic frequency of 40kHz and an ultrasonic power of 180W.

[0151] S6: Place chip 200 in groove 50 and solder it.

[0152] The soldering conditions included: soldering the chip to the copper layer grooves using nano-silver solder paste under inert gas (N2) protection. The soldering temperature was 300℃, the soldering pressure was 20MPa, and the holding time was 3min.

[0153] Example 2

[0154] The difference between this embodiment and Embodiment 1 is that: the diamond sheet is a polycrystalline diamond sheet; the first Ti-containing metal layer is composed of a 150nm thick titanium layer prepared first and a 2000nm thick tungsten layer prepared later; the second Ti-containing metal layer is also composed of a 150nm thick titanium layer prepared first and a 2000nm thick tungsten layer prepared later.

[0155] Example 3

[0156] The difference between this embodiment and Embodiment 1 is that the diamond sheet is a polycrystalline diamond sheet; both the first and second solders are copper-titanium-tin solders with a thickness of 0.05 mm. Vacuum brazing involves first heating to 650°C at a rate of 10°C / min, holding at that temperature for 30 minutes, then further heating to 880°C at a rate of 5°C / min, holding at that temperature for 20 minutes, followed by cooling to 500°C at a rate of 3°C / min, holding at that temperature for 30 minutes, and then cooling with the furnace.

[0157] Example 4

[0158] The difference between this embodiment and Embodiment 2 is that the diamond sheet is a CVD polycrystalline diamond sheet.

[0159] Example 5

[0160] This embodiment provides an on-board SiC chip packaged heat sink 300, the preparation method of which includes:

[0161] S1: Material preparation.

[0162] S1-1: Prepare the first copper foil and the second copper foil.

[0163] Vacuum annealing, acid etching, ultrasonic cleaning, and drying were performed on the first oxygen-free copper foil (0.1 mm thick) and the second oxygen-free copper foil (0.1 mm thick).

[0164] The vacuum annealing heat treatment was carried out at a temperature of 450℃ for 3 hours.

[0165] The acid etching process includes: acid etching the above oxygen-free copper foil for 30 seconds using a copper oxide cleaner to remove oxides and other impurities from the surface of the copper foil.

[0166] The ultrasonic cleaning was performed at a frequency of 35 kHz and a power of 160 W. The ultrasonic cleaning process was carried out at room temperature, with ethanol and pure water used for ultrasonic cleaning for 3 minutes each, sequentially.

[0167] S1-2: Prepare the first solder and the second solder.

[0168] The first solder (0.02mm thick silver-copper-titanium solder) and the second solder (0.02mm thick silver-copper-titanium solder) were ultrasonically cleaned and dried. The ultrasonic cleaning frequency was 35kHz and the power was 160W. The ultrasonic cleaning process was carried out at room temperature, with acetone, ethanol, and pure water used sequentially for 3 minutes each.

[0169] S1-3: Prepare modified diamond sheets.

[0170] S1-3-1: A CVD single-crystal diamond wafer with a diameter of 50.8 mm and a thickness of 0.1 mm was selected. The roughness Ra of both sides of the diamond wafer was 0.1 μm, and the in-plane resistivity was 600 MΩ. The diamond wafer was subjected to plasma cleaning under the following conditions: power of 1100 W, gas flow rate of 70 sccm, pressure of 45 Pa, time of 6 min, and radio frequency of 13 MHz. Subsequently, it was ultrasonically cleaned sequentially at room temperature with acetone, ethanol, and pure water for 3 min each, with an ultrasonic frequency of 35 kHz and a power of 160 W, and then dried.

[0171] S1-3-2: Using magnetron sputtering, a first Ti-containing metal layer (including a 150nm thick titanium layer and a 850nm thick copper layer) and a second Ti-containing metal layer (including a 150nm thick titanium layer and a 850nm thick copper layer) are prepared on the upper and lower surfaces of the dried diamond sheet, respectively. Then, vacuum annealing is performed to obtain the first TiC layer 31 and the second TiC layer 32.

[0172] The magnetron sputtering process involved a power of 100W, a duration of 3 hours, a target-substrate distance of 3cm, an argon flow rate of 10sccm, and a vacuum level of less than 3×10⁻⁶. -3 Pa.

[0173] The vacuum annealing heat treatment was performed at a temperature of 450℃ for 3 hours.

[0174] S2: The first copper foil, the first solder, the modified diamond sheet, the second solder, and the second copper foil are stacked sequentially and then vacuum brazed to obtain a first intermediate heat dissipation plate having a first copper layer 11, a first brazing layer 21, a first TiC layer 31, a diamond sheet layer 40, a second TiC layer 32, a second brazing layer 22, and a second copper layer 12; the surface of the copper layer of the first intermediate heat dissipation plate is mechanically ground and polished to make its surface roughness 0.2μm.

[0175] The vacuum brazing process includes: at a vacuum level of 10... -1 Under the conditions of Pa and brazing pressure of 0.1 MPa, the temperature is first raised to 620℃ at a rate of 12℃ / min, held for 35 min, then raised to 850℃ at a rate of 5℃ / min, held for 25 min, then cooled to 400℃ at a rate of 2℃ / min, held for 35 min, and then cooled with the furnace.

[0176] S3: A groove 50 is provided on the surface of the first copper layer 11 of the first intermediate heat dissipation plate.

[0177] The first intermediate heat dissipation plate is subjected to lamination, exposure, development, plasma dry etching, and film removal to form multiple grooves 50.

[0178] The lamination conditions include: using HMDS for adhesion enhancement, using positive photoresist, and laminating the film at 90°C and 800 rpm for 95 seconds.

[0179] Exposure conditions include: 280 mJ / cm on the exposure machine. 2 Exposure energy is used for exposure.

[0180] The development conditions include: using a 2% tetramethylammonium hydroxide developer, spraying for 8 seconds, letting stand for 45 seconds, rinsing thoroughly with deionized water, and baking at 90°C for 95 seconds to strengthen the photoresist.

[0181] The plasma etching conditions included: using Cl2 (45 sccm) and N2 (15 sccm), etching copper trenches at a chamber pressure of 8 mTorr, a plasma power of 900 W, a bias power of 180 W, and a temperature of 75 °C.

[0182] The film removal process conditions include: using O2 plasma ashing to remove the dry film at a chamber pressure of 900 mTorr, a power of 1400 W, and a processing temperature of 180 °C, followed by wet cleaning to thoroughly remove organic matter.

[0183] Each groove 50 has a depth of 0.2mm, a width of 6mm, and a length of 6mm.

[0184] S4: A first nickel layer and a first gold layer are sequentially electroplated on the outer surface of the first copper layer 11 with groove 50, and a second nickel layer and a second gold layer are sequentially electroplated on the outer surface of the second copper layer 12 to obtain a heat dissipation substrate 100.

[0185] The thickness of the first nickel layer and the second nickel layer is 1 μm, and the thickness of the first gold layer and the second gold layer is 0.1 μm.

[0186] S5: The heat sink substrate 100 is slit and plasma cleaned.

[0187] The slitting process uses laser slitting with a power of 18W, a speed of 750mm / s, a frequency of 45KHz, a pulse width of 8PS, and a voltage of 200V.

[0188] The plasma cleaning conditions included: power of 1100W, gas flow rate of 70sccm, pressure of 45Pa, time of 6min, and radio frequency of 13MHz. Subsequently, acetone, ethanol, and pure water were used for ultrasonic cleaning for 3min each at room temperature, with an ultrasonic frequency of 35kHz and a power of 160W.

[0189] S6: Place chip 200 in groove 50 and solder it.

[0190] The soldering conditions included: soldering the chip to the copper layer grooves using nano-silver solder paste under inert gas (N2) protection. The soldering temperature was 300℃, the soldering pressure was 20MPa, and the holding time was 3min.

[0191] Example 6

[0192] This embodiment provides an on-board SiC chip packaged heat sink 300, the preparation method of which includes:

[0193] S1: Material preparation.

[0194] S1-1: Prepare the first copper foil and the second copper foil.

[0195] Vacuum annealing, acid etching, ultrasonic cleaning, and drying were performed on the first oxygen-free copper foil (1 mm thick) and the second oxygen-free copper foil (1 mm thick).

[0196] The vacuum annealing heat treatment was carried out at a temperature of 650℃ for 1 hour.

[0197] The acid etching process includes: acid etching the above oxygen-free copper foil for 30 seconds using a copper oxide cleaner to remove oxides and other impurities from the surface of the copper foil.

[0198] The ultrasonic cleaning was performed at a frequency of 45 kHz and a power of 200 W. The ultrasonic cleaning process was carried out at room temperature, with ethanol and pure water used for ultrasonic cleaning for 1 minute each, sequentially.

[0199] S1-2: Prepare the first solder and the second solder.

[0200] The first solder (0.1 mm thick silver-copper-titanium solder) and the second solder (0.1 mm thick silver-copper-titanium solder) were ultrasonically cleaned and dried. The ultrasonic cleaning frequency was 45 kHz and the power was 200 W. The ultrasonic cleaning process was carried out at room temperature, with acetone, ethanol, and pure water used sequentially for 1 minute each.

[0201] S1-3: Prepare modified diamond sheets.

[0202] S1-3-1: A CVD single-crystal diamond wafer with a diameter of 50.8 mm and a thickness of 0.5 mm was selected. The roughness Ra of both sides of the diamond wafer was 0.8 μm, and the in-plane resistivity was 550 MΩ. The diamond wafer was subjected to plasma cleaning under the following conditions: power of 1300 W, gas flow rate of 90 sccm, pressure of 55 Pa, time of 4 min, and radio frequency of 14 MHz. Subsequently, it was ultrasonically cleaned for 1 min each with acetone, ethanol, and pure water at room temperature, with an ultrasonic frequency of 45 kHz and a power of 200 W, and then dried.

[0203] S1-3-2: Using magnetron sputtering, a first Ti-containing metal layer (including a 150nm thick titanium layer and a 2850nm thick copper layer) and a second Ti-containing metal layer (including a 150nm thick titanium layer and a 2850nm thick copper layer) are prepared on the upper and lower surfaces of the dried diamond sheet, respectively. Then, vacuum annealing is performed to obtain the first TiC layer 31 and the second TiC layer 32.

[0204] The magnetron sputtering process involved a power of 160W, a duration of 1 hour, a target-substrate distance of 12cm, an argon flow rate of 30sccm, and a vacuum level of less than 3×10⁻⁶. -3 Pa.

[0205] The vacuum annealing heat treatment was performed at a temperature of 650℃ for 1 hour.

[0206] S2: The first copper foil, the first solder, the modified diamond sheet, the second solder, and the second copper foil are stacked sequentially and then vacuum brazed to obtain a first intermediate heat dissipation plate having a first copper layer 11, a first brazing layer 21, a first TiC layer 31, a diamond sheet layer 40, a second TiC layer 32, a second brazing layer 22, and a second copper layer 12; the surface of the copper layer of the first intermediate heat dissipation plate is mechanically ground and polished to make its surface roughness 0.2μm.

[0207] The vacuum brazing process includes: at a vacuum level of 10... -4 Under the conditions of Pa and a brazing pressure of 5 MPa, the temperature is first raised to 680℃ at a rate of 10℃ / min, held for 25 min, then raised to 900℃ at a rate of 5℃ / min, held for 15 min, then cooled to 700℃ at a rate of 4℃ / min, held for 25 min, and then cooled with the furnace.

[0208] S3: A groove 50 is provided on the surface of the first copper layer 11 of the first intermediate heat dissipation plate.

[0209] The first intermediate heat dissipation plate is subjected to lamination, exposure, development, plasma dry etching, and film removal to form multiple grooves 50.

[0210] The lamination conditions include: using HMDS for adhesion enhancement, using positive photoresist, and laminating the film at 110°C and 1200 rpm for 85 seconds.

[0211] Exposure conditions include: 320 mJ / cm on the exposure machine. 2 Exposure energy is used for exposure.

[0212] The development conditions include: using a 2.5% tetramethylammonium hydroxide developer, spraying for 12 seconds, letting stand for 55 seconds, rinsing thoroughly with deionized water, and baking at 110°C for 85 seconds to strengthen the photoresist.

[0213] The plasma etching conditions included: using Cl2 (55 sccm) and N2 (25 sccm), etching copper trenches at a chamber pressure of 12 mTorr, a plasma power of 1100 W, a bias power of 220 W, and a temperature of 85 °C.

[0214] The film removal process conditions include: using O2 plasma ashing to remove the dry film at a chamber pressure of 1100 mTorr, a power of 1600 W, and a processing temperature of 220 °C, followed by wet cleaning to thoroughly remove organic matter.

[0215] Each groove 50 has a depth of 0.2mm, a width of 6mm, and a length of 6mm.

[0216] S4: A first nickel layer and a first gold layer are sequentially electroplated on the outer surface of the first copper layer 11 with groove 50, and a second nickel layer and a second gold layer are sequentially electroplated on the outer surface of the second copper layer 12 to obtain a heat dissipation substrate 100.

[0217] The thickness of the first nickel layer and the second nickel layer is 3 μm, and the thickness of the first gold layer and the second gold layer is 1 μm.

[0218] S5: The heat sink substrate 100 is slit and plasma cleaned.

[0219] The slitting process uses laser slitting with a power of 22W, a speed of 850mm / s, a frequency of 55KHz, a pulse width of 12PS, and a voltage of 240V.

[0220] The plasma cleaning conditions included: power of 1300W, gas flow rate of 90sccm, pressure of 55Pa, time of 4min, and radio frequency of 14MHz. Subsequently, the plasma was ultrasonically cleaned for 1min each with acetone, ethanol, and pure water at room temperature, with an ultrasonic frequency of 45kHz and a power of 200W.

[0221] S6: Place chip 200 in groove 50 and solder it.

[0222] The soldering conditions included: soldering the chip to the copper layer grooves using nano-silver solder paste under inert gas (N2) protection. The soldering temperature was 300℃, the soldering pressure was 20MPa, and the holding time was 3min.

[0223] Comparative Example 1

[0224] The difference between this comparative example and Example 1 is that the first copper layer 11 does not have a groove 50, and the chip 200 is directly bonded to the surface of the first copper layer 11.

[0225] Comparative Example 2

[0226] The difference between this comparative example and Example 1 is that the thickness of both the first brazing layer 21 and the second brazing layer 22 is 0.2 mm.

[0227] Comparative Example 3

[0228] The difference between this comparative example and Example 1 is that the materials of both the first Ti-containing metal coating and the second Ti-containing metal coating are only titanium.

[0229] Comparative Example 4

[0230] The difference between this comparative example and Example 1 is that the total thickness of both the first Ti-containing metal coating and the second Ti-containing metal coating is 0.5 μm.

[0231] Comparative Example 5

[0232] The difference between this comparative example and Example 1 is that there is no first TiC layer 31 between the first brazing layer 21 and the diamond layer, and there is no second TiC layer 32 between the second brazing layer 22 and the diamond layer.

[0233] Comparative Example 6

[0234] The difference between this comparative example and Example 1 is that: the outer surface of the first copper layer 11 does not have a first nickel layer and a first gold layer; the outer surface of the second copper layer 12 does not have a second nickel layer and a second gold layer.

[0235] Comparative Example 7

[0236] The difference between this comparative example and Example 1 is that: before preparing the first Ti-containing metal layer and the second Ti-containing metal layer, only the diamond sheet was ultrasonically cleaned and dried, and no plasma cleaning was performed before ultrasonic cleaning.

[0237] Comparative Example 8

[0238] The difference between this comparative example and Example 1 is that during the vacuum brazing process, the temperature is directly raised to 880°C at a rate of 10°C / min and held for 20 minutes, without the previous stage of "raising the temperature to 650°C and holding for 30 minutes".

[0239] Comparative Example 9

[0240] The difference between this comparative example and Example 1 is that during the vacuum brazing process, after heating to 880°C and holding for 20 minutes, the temperature is directly cooled with the furnace, without the intermediate stage of "cooling down to 500°C at a cooling rate of 3°C / min and holding for 30 minutes".

[0241] Test case

[0242] The performance of the automotive SiC chip package heat sinks prepared in Examples 1-6 and Comparative Examples 1-9 was compared, and the results are shown in Table 1.

[0243] Thermal conductivity was tested in accordance with GB / T 22588-2008, and the number of thermal shocks (thermal shock test) was tested in accordance with GB_T5270-2005.

[0244] Table 1 Test Results

[0245]

[0246] As can be seen from Table 1, the vehicle-mounted SiC chip package heat sink 300 prepared in Examples 1-6 of the present invention has high thermal conductivity and high thermal shock resistance.

[0247] The results from Example 1 and Comparative Example 1 show that when the first copper layer 11 does not have a groove 50 and the chip is directly bonded to the surface of the first copper layer, the thermal conductivity and thermal shock resistance of the corresponding automotive SiC chip package heat sink are significantly reduced.

[0248] The results from Example 1 and Comparative Example 2 show that when the first brazing layer 21 and the second brazing layer 22 are thicker, the welding stress is greater, which leads to a significant reduction in the thermal conductivity and thermal shock resistance of the automotive SiC chip package heat sink.

[0249] The results from Example 1 and Comparative Example 3 show that when both the first Ti-containing metal coating and the second Ti-containing metal coating are made of titanium, the thermal conductivity and thermal shock resistance of the automotive SiC chip package heat sink will also be reduced.

[0250] The results from Example 1 and Comparative Example 4 show that when the total thickness of the first Ti-containing metal coating and the second Ti-containing metal coating is thin, too little TiC is generated, making it difficult to effectively improve the interfacial bonding strength, which leads to a decrease in the thermal conductivity and thermal shock resistance of the automotive SiC chip packaging heat sink.

[0251] The results from Example 1 and Comparative Example 5 show that when there is no TiC layer between the brazing layer and the diamond layer, the interfacial bonding strength between the brazing layer and the diamond layer is weak, which leads to a decrease in the thermal conductivity and thermal shock resistance of the automotive SiC chip packaging heat sink.

[0252] The results from Example 1 and Comparative Example 6 show that when the outer surface of the copper layer is not provided with nickel and gold layers, the thermal conductivity and thermal shock resistance of the automotive SiC chip package heat sink will also be reduced.

[0253] The results from Example 1 and Comparative Example 7 show that the absence of plasma cleaning before ultrasonic cleaning reduces the bonding force between the first TiC layer 31, the diamond sheet layer 40, and the second TiC layer 32, thereby reducing the thermal conductivity and thermal shock resistance of the automotive SiC chip packaging heat sink.

[0254] The results of Example 1 and Comparative Examples 8-9 show that improper setting of the heating or cooling process in vacuum brazing can reduce the thermal conductivity and thermal shock resistance of the automotive SiC chip package heat sink.

[0255] In summary, the automotive SiC chip packaging heat sink 300 provided by this invention has significant advantages over the existing ceramic copper-clad heat sink substrate 100: the thermal conductivity of the common alumina ceramic copper-clad heat sink substrate 100 is approximately 24 W / mK, that of the silicon nitride ceramic copper-clad heat sink substrate 100 is approximately 90 W / mK, and that of the aluminum nitride ceramic copper-clad heat sink substrate 100 is approximately 180 W / mK, while the thermal conductivity of the automotive SiC chip packaging heat sink 300 provided by this invention is no less than 350 W / mK, which is significantly improved compared to the aforementioned ceramic copper-clad heat sink substrate 100. Furthermore, the manufacturing process of the automotive SiC chip packaging heat sink 300 provided by this invention is simple, cost-controllable, and industrially feasible. The resulting automotive SiC chip packaging heat sink 300 can efficiently dissipate heat under high heat flux density, high temperature, high pressure, and high frequency conditions, and can effectively avoid thermal stress and thermal fatigue that could cause premature failure of the chip 200, thereby ensuring high reliability and a long service life.

[0256] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heat dissipating substrate, characterized by, The heat dissipation substrate comprises a first copper layer, a first brazing layer, a first TiC layer, a diamond sheet layer, a second TiC layer, a second brazing layer and a second copper layer which are sequentially stacked; a side surface of the first copper layer away from the diamond sheet layer is provided with a groove for placing a chip; an outer surface of the first copper layer is sequentially provided with a first nickel layer and a first gold layer from inside to outside; an outer surface of the second copper layer is sequentially provided with a second nickel layer and a second gold layer from inside to outside; Thicknesses of the first brazing layer and the second brazing layer are independently 0.02mm-0.1mm; Thermal conductivity of the heat dissipation substrate is not less than 405W / mk; and the number of thermal shock of the heat dissipation substrate is not less than 22 times; Preparation of the heat dissipation substrate comprises the following steps: A first copper foil, a first solder, a modified diamond sheet, a second solder and a second copper foil are sequentially stacked, and then vacuum brazing treatment is performed to obtain a first intermediate heat dissipation plate material having a first copper layer, a first brazing layer, a first TiC layer, a diamond sheet layer, a second TiC layer, a second brazing layer and a second copper layer; the groove is arranged on a surface of the first copper layer of the first intermediate heat dissipation plate material; a first nickel layer and a first gold layer are sequentially electroplated on an outer surface of the first copper layer having the groove, and a second nickel layer and a second gold layer are sequentially electroplated on an outer surface of the second copper layer; wherein the modified diamond sheet comprises a diamond sheet layer, a first TiC layer on an upper surface of the diamond sheet and a second TiC layer on a lower surface of the diamond sheet; Preparation of the modified diamond sheet comprises: preparing a first Ti-containing metal layer and a second Ti-containing metal layer on an upper surface and a lower surface of a diamond sheet respectively, and then performing vacuum annealing treatment to form the first TiC layer on the upper surface of the diamond sheet by the first Ti-containing metal layer and to form the second TiC layer on the lower surface of the diamond sheet by the second Ti-containing metal layer; The first Ti-containing metal coating is made of at least one of titanium copper, titanium tungsten and titanium chromium; thickness of the first Ti-containing metal coating is 1μm-3μm; the second Ti-containing metal coating is made of at least one of titanium copper, titanium tungsten and titanium chromium; thickness of the second Ti-containing metal coating is 1μm-3μm; Before preparing the first Ti-containing metal layer and the second Ti-containing metal layer, the diamond sheet is subjected to plasma cleaning, ultrasonic cleaning and drying; wherein power of the plasma cleaning is 1100W-1300W, gas flow rate of the plasma cleaning is 70sccm-90sccm, pressure of the plasma cleaning is 45Pa-55Pa, time of the plasma cleaning is 4min-6min, and radio frequency frequency of the plasma cleaning is 13MHz-14MHz; The vacuum brazing includes: under the conditions of a vacuum degree of 10 -1 Pa 10 -4 Pa and a brazing pressure of 0.1 MPa to 5 MPa, first heating to 620 DEG C to 680 DEG C, holding for 25 min to 35 min, then continuously heating to 850 DEG C to 900 DEG C, holding for 15 min to 25 min, then cooling to 400 DEG C to 700 DEG C, holding for 25 min to 35 min, and then cooling with the furnace.

2. The heat dissipating substrate according to claim 1, wherein The diamond sheet layer comprises at least one of the following features: Feature 1: when the diamond sheet used for the diamond sheet layer is a single crystal diamond sheet, thermal conductivity of the diamond sheet is greater than 2000W / mk; when the diamond sheet used for the diamond sheet layer is a polycrystalline diamond sheet, thermal conductivity of the diamond sheet is greater than 1200W / mk; Feature 2: the surface roughness of the diamond sheet used by the diamond sheet layer is 0.1-0.8 μm; Feature 3: the in-plane resistance of the diamond sheet used by the diamond sheet layer is not less than 500 mΩ; Feature 4: the thickness of the diamond sheet used by the diamond sheet layer is 0.1-0.5 mm.

3. The heat dissipating substrate according to claim 1, wherein The solder used by the first and second brazing layers independently comprises at least one of silver-copper-titanium, silver-copper-chromium and copper-titanium-tin; And / or, the thickness of the first and second copper layers is independently 0.1-1 mm.

4. The heat dissipating substrate according to claim 1, wherein The thickness of the first nickel layer is 1-3 μm, and the thickness of the first gold layer is 0.1-1 μm; the thickness of the second nickel layer is 1-3 μm, and the thickness of the second gold layer is 0.1-1 μm.

5. A method of producing the heat dissipating substrate according to any one of claims 1 to 4, characterized by, The method comprises the following steps: The first copper foil, the first solder, the modified diamond sheet, the second solder and the second copper foil are sequentially stacked to obtain a first intermediate heat dissipation plate material having a first copper layer, a first brazing layer, a first TiC layer, a diamond sheet layer, a second TiC layer, a second brazing layer and a second copper layer; the recess is arranged on the surface of the first copper layer of the first intermediate heat dissipation plate material; the first nickel layer and the first gold layer are sequentially electroplated on the outer surface of the first copper layer having the recess, and the second nickel layer and the second gold layer are sequentially electroplated on the outer surface of the second copper layer; The modified diamond sheet comprises a diamond sheet layer, a first TiC layer on the upper surface of the diamond sheet and a second TiC layer on the lower surface of the diamond sheet; The preparation of the modified diamond sheet comprises: preparing a first Ti-containing metal layer and a second Ti-containing metal layer on the upper surface and the lower surface of the diamond sheet, respectively, and then performing vacuum annealing treatment, so that the first Ti-containing metal layer forms the first TiC layer on the upper surface of the diamond sheet, and the second Ti-containing metal layer forms the second TiC layer on the lower surface of the diamond sheet; Before preparing the first and second Ti-containing metal layers, the diamond sheet is subjected to plasma cleaning, ultrasonic cleaning and drying; the power of the plasma cleaning is 1100-1300 W, the gas flow rate of the plasma cleaning is 70-90 sccm, the pressure of the plasma cleaning is 45-55 Pa, the time of the plasma cleaning is 4-6 min, and the radio frequency of the plasma cleaning is 13-14 MHz; The vacuum brazing includes: under the conditions of a vacuum degree of 10 -1 Pa 10 -4 Pa and brazing pressure of 0.1 MPa-5 MPa, first heated to 620-680 ℃, and then heated to 850-900 ℃ after holding for 25-35 min, and then cooled to 400-700 ℃ after holding for 15-25 min, and then cooled with the furnace.

6. The preparation method according to claim 5, characterized in that, The temperature of the vacuum annealing heat treatment is 450-650 ℃, and the time of the vacuum heat treatment is 1-3 h.

7. The preparation method according to claim 5, characterized in that, The frequency of the ultrasonic cleaning is 35-45 kHz, and the power of the ultrasonic cleaning is 160-200 W.

8. The preparation method according to claim 5, characterized in that, The first and second Ti-containing metal layers are prepared by a magnetron sputtering method; The magnetron sputtering conditions include: direct current sputtering power is 100W-160W, sputtering time is 1h-3h, target-substrate distance is 3cm-12cm, argon flow rate is 10sccm-30sccm, vacuum degree is less than 3x10 -3 Pa.

9. The preparation method according to claim 5, characterized in that, Before the stacking, the first and second solders are subjected to ultrasonic cleaning and drying; And / or, before the stacking, the first and second copper foils are subjected to vacuum annealing treatment, acid etching, ultrasonic cleaning and drying.

10. The method of claim 5, wherein, The setting process of the groove comprises: pressing film, exposure, development, plasma etching and film removal treatment on the first intermediate heat dissipation plate.

11. The method of claim 5, wherein, Further comprising: slitting and plasma cleaning the heat dissipation substrate; The slitting is performed by laser slitting, the power of the laser slitting is 18W~22W, the speed of the laser slitting is 750mm / s~850mm / s, the frequency of the laser slitting is 45KHz~55KHz, the pulse width of the laser slitting is 8PS~12PS, and the voltage of the laser slitting is 200V~240V.

12. A SiC chip package heat spreader for an automotive vehicle, characterized by, The chip is welded in the groove of the first copper layer of the heat dissipation substrate.

13. An automobile characterized by comprising: The automobile comprises the heat dissipation substrate according to any one of claims 1~6 or the vehicle-mounted SiC chip packaging heat dissipation plate according to claim 12.

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