A bionic honeycomb substrate for power device packaging, its preparation method and application

Abstract

The present invention relates to the field of power electronic device packaging technology, and in particular to a bionic honeycomb substrate for power device packaging and its preparation method and application. The substrate surface has a bionic honeycomb patterned dual-scale micro-nano structure, including: a honeycomb pattern structure composed of a micron-scale structure: a closely packed regular hexagon with a side length of 1.5-1.7mm, a circle with a diameter of 1mm in the center of the regular hexagon, a micro-cone array with a spacing of 30-40μm and a height of 40-50μm inside the circle, and the rest is a ring-shaped filled micro-groove with a spacing of 30-40μm and a depth of 20-50μm; a nanoscale structure: nanoparticles attached to the entire substrate surface, with a particle size of 50-300nm. The present invention uses a honeycomb structure with stability in nature as a template, first prepares a micro-nano dual-scale patterned structure on the surface of a Cu substrate by ultrafast laser, and then performs sintering of nanosilver for interconnection with a chip, significantly improving the connection strength of the sintered silver, and realizing high-reliability packaging of third-generation semiconductors.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic device packaging, and in particular to a bionic honeycomb substrate for power device packaging, and a preparation method and application thereof. Background Art

[0002] As the power density of power devices gradually increases, third-generation semiconductor technology, represented by SiC, has developed. Due to its ability to operate at higher temperatures, high frequency, and wide bandgap, it has been widely used in high-speed rail, 5G, electric vehicles, and other fields. Since third-generation semiconductors operate at high temperatures, approaching or exceeding the melting point of traditional Sn-based solders, nanosilver sintering technology will be used to encapsulate SiC chips. Due to the size effect, nanosilver possesses high surface energy and can be sintered at relatively low temperatures and pressures. The physical properties after sintering are similar to those of bulk silver, achieving "low-temperature sintering and high-temperature service." Silver also has high electrical and thermal conductivity and is not susceptible to oxidation during the sintering process, making it an excellent packaging material. However, due to the low surface energy of the Cu substrate and the lack of diffusion between it and Ag, the Cu / Ag heterojunction interface is poor, resulting in poor mechanical properties of the interconnect structure and the risk of packaging failure. To achieve high-reliability packaging of third-generation semiconductors, the Cu substrate is treated to improve the interface bonding strength. In industry, Ag plating is performed on the chip position, which can significantly improve the connection strength. However, this method uses precious metal Ag, which increases costs, and the long coating time will reduce production efficiency. At the same time, electroplating or chemical plating will produce waste liquid that pollutes the environment.

[0003] Ultrafast lasers have ultrashort pulse durations, resulting in a minimal heat-affected zone (HAZ) during processing, effectively mimicking "cold processing" and resulting in extremely high processing quality. Laser processing is also characterized by high efficiency, high repeatability, a relatively simple process, and a pollution-free nature. Currently, research is underway to enhance the mechanical properties of dissimilar material connections using ultrafast lasers to construct interface structures. Tsinghua University reported using femtosecond lasers to etch grooves on ceramic surfaces and braze stainless steel connections, increasing their strength by 1.8 times (Materials Science and Engineering: A, 2016, 662: 178-184, Yingchuan Zhang, et al., "Vacuum brazing of alumina to stainless steel using femtosecond laser patterned periodic surface structure"). However, the characteristic scale of the structure is typically a single micrometer, lacking high surface energy. Furthermore, after packaging using this substrate, the mechanical properties vary considerably in different directions. Prior art (CN109473418A) provides a copper interconnect functional microstructure, but in actual production, the upper substrate is a chip, making laser processing unsuitable, and solder paste must be applied to the lower substrate. Summary of the Invention

[0004] The purpose of the present invention is to provide a bionic honeycomb substrate for power device packaging, as well as its preparation method and application. Using the stable honeycomb structure in nature as a template, the present invention first uses an ultrafast laser to prepare a micro-nano dual-scale patterned structure on the surface of a Cu substrate, and then sintering nanosilver to interconnect with the chip, significantly improving the connection strength of the sintered silver and realizing high-reliability packaging of third-generation semiconductors. The process is simple, cost-effective, and green manufacturing can solve the above-mentioned technical problems.

[0005] The present invention provides a bionic honeycomb substrate for power device packaging, the surface of which has a bionic honeycomb patterned dual-scale micro-nano structure, including:

[0006] A honeycomb pattern structure composed of micron-scale structures: densely packed regular hexagons with a side length of 1.5-1.7 mm. There is a circle with a diameter of 1 mm in the center of the regular hexagon. The interior of the circle is filled with a micro-cone array with a spacing of 30-40 μm and a height of 40-50 μm. The rest of the circle is filled with annular micro-grooves with a spacing of 30-40 μm and a depth of 20-50 μm.

[0007] Nanoscale structure: Nanoparticles attached to the entire surface of the substrate, with a particle size of 50-300nm.

[0008] Each regular hexagon is a "unit", and each circular area is located in each regular hexagonal unit, such asFigure 5 shown.

[0009] The present invention also provides a method for preparing a bionic honeycomb substrate for power device packaging, which is prepared by an ultrafast laser "two-step method". An ultrafast laser processing system is used to process a pre-treated substrate. In the first step, a rapid scanning method is used to construct a patterned micron-scale structure. In the second step, a slow scanning method is used to in-situ deposit nanoparticles on the surface of the substrate with the micron-scale structure. The method specifically includes the following steps:

[0010] Step 1: Grind and polish the Cu substrate;

[0011] Step 2: Using an ultrafast laser processing system, patterned micron-scale structures are prepared by rapid scanning;

[0012] Step 3: The patterned micron-scale structure surface completed in step 2 is constructed into a nanoscale structure using an ultrafast laser processing system;

[0013] Step 4: pickling the substrate with the micro-nanostructured surface prepared in step 3, ultrasonically cleaning it after pickling, drying it, and setting it aside;

[0014] Specifically, 1. Grind and polish the package substrate to remove the oxide film and ensure a smooth surface;

[0015] 2. Use an ultrafast laser processing system to construct micron-scale patterned structures on the substrate surface. The ultrafast laser processing system consists of an ultrafast laser, a set of reflectors, a beam shaping mirror, a scanning galvanometer, a focusing mirror, a translation stage, and a beam quality detector. The reflector collimates the light beam into the scanning galvanometer, and the beam shaping mirror adjusts the polarization direction of the laser beam to circularly polarized light and expands the beam to obtain a smaller spot after focusing.

[0016] 3. Construct a micron-scale structure with a bionic honeycomb pattern on the substrate surface. The patterned structure is constructed by setting the scanning path. The galvanometer scanning speed is greater than 1m / s. By changing the laser processing parameters, the depth of the surface microstructure can be controlled.

[0017] 4. The processed substrate is then subjected to in-situ deposition of nanoscale structures using an ultrafast laser processing system. A laser with a strength greater than the damage threshold of the substrate material is scanned at intervals less than 50 μm. At a scanning speed of 50 mm / s, the laser-excited plasma recasts onto the substrate, filling the substrate surface with nanoparticles, thereby producing a micro-nano dual-scale patterned substrate.

[0018] 5. The processed substrate with the surface micro-nano dual-scale patterned structure was placed in 5 mol / L dilute nitric acid for ultrasonic cleaning for 1 minute to remove the oxides generated during processing, and then placed in anhydrous ethanol for ultrasonic cleaning for 5 minutes until all the acid was washed away.

[0019] Preferably, the laser scanning path in step 2 is the same as the honeycomb pattern structure of the substrate.

[0020] Preferably, the specific process of step 3 is to construct a nanoscale structure by in-situ depositing nanoparticles on the substrate surface by controlling the scanning speed.

[0021] Preferably, before polishing the Cu substrate in step 1, the Cu substrate is immersed in a prepared 30% HNO3 aqueous solution for a few minutes to remove oxides and contaminants on the surface of the Cu substrate, and then placed in acetone for further ultrasonic cleaning. After cleaning, it is dried and polished with sandpaper to ensure that the oxide layer is completely removed and the connection surface is level.

[0022] The substrate may also be a DBC substrate or a DBA substrate.

[0023] Preferably, the ultrafast laser processing system comprises:

[0024] Ultrafast laser, used to emit ultrafast laser as a laser source for laser processing;

[0025] A reflector assembly, used to refract the ultrafast laser so that it can be collimated and directed to a predetermined position;

[0026] Beam shaping, including beam expanders and wave plates, to adjust the size and polarization direction of the light spot;

[0027] CCD, used to observe the laser status and beam quality;

[0028] Scanning galvanometer, which drives the internal reflective mirror to move through the movement of the motor, used for beam movement;

[0029] Focusing field lens, which focuses the laser on the sample surface and increases the power density;

[0030] In addition, there is a laser workstation and a control card to control the laser emission and the movement of the galvanometer.

[0031] Preferably, the ultrafast laser is a femtosecond laser or a picosecond laser, and the pulse width reaches below the picosecond level, so the micro-nanostructure processing quality is high, which is similar to cold processing.

[0032] Preferably, the controllable preparation of the micro-nano structure is achieved by controlling the scanning path, laser power, laser frequency, and processing times of the ultrafast laser.

[0033] Preferably, the scanning path for in-situ deposition of nanoscale structures is the same as the scanning path for constructing micrometer-scale patterned structures.

[0034] The present invention also provides an application of a bionic honeycomb substrate for power device packaging, wherein nanosilver is used as the substrate for power device packaging for interconnection, and the process is as follows:

[0035] Step 21: Clean the bionic honeycomb substrate for power device packaging, cover it with a mask, and apply nano-silver solder paste;

[0036] Step 22: Let it sit for a while, then use tweezers to hold the edge of the mask and lift it vertically upwards;

[0037] Step 23: Gently place the chip on the nanosilver solder paste, ensuring that the entire chip is on top of the solder paste;

[0038] Step 24: Place the structure obtained in step 23 into a hot pressing sintering machine for hot pressing and sintering, followed by air cooling;

[0039] Step 25: Perform a shear test on the interconnection structure obtained in step 24 to determine the effect of the surface micro-nanostructure on enhancing the connection strength;

[0040] Specifically, the bionic honeycomb substrate for power device packaging of the present invention can be used as a substrate for power device packaging. The bionic honeycomb substrate has a densely packed pattern that is stable and isotropic. The micron-scale grooves and micro-cone arrays increase the interconnection area. The nano-scale particle structure significantly increases the surface energy of the substrate, thereby enhancing the connection strength of the interconnection joints. The specific application method is as follows:

[0041] 1. Before packaging, the bionic honeycomb substrate used for power device packaging was ultrasonically cleaned in 5 mol / L dilute nitric acid to remove the surface oxide film;

[0042] 2. Place the mask with the required solder paste thickness on the bionic honeycomb substrate, apply the nanosilver solder paste evenly on the mask, and use a scraper to ensure that the thickness of each area in the array is consistent;

[0043] 3. After applying the solder paste, let it stand for a while to allow some volatile organic matter to evaporate and the fluidity of the solder paste to decrease. At this time, use tweezers to hold the edge of the mask and lift the mask vertically upwards;

[0044] 4. Gently place the chip on the nano silver solder paste, ensuring that the entire chip is on top of the solder paste, and then place the whole thing in the hot press sintering machine;

[0045] 5. Preheating at a certain temperature, during which the organic matter volatilizes and the silver paste solidifies, and then hot pressing and sintering are performed to complete the interconnection, thereby obtaining an interconnection joint of a bionic honeycomb substrate for power device packaging;

[0046] 6. The shear test of the above joints was carried out. The bionic honeycomb substrate for power device packaging can significantly enhance the connection strength of sintered silver.

[0047] Preferably, the substrate and the chip are arranged in parallel, and the surfaces of the substrate facing the chip are flat.

[0048] Preferably, the chip is made of a material used in power devices.

[0049] Preferably, the bottom surface of the chip is plated with an Ag layer or sputtered with a metal layer.

[0050] Preferably, the heating rate of the sintering machine in step 24 is 5° C. / min, preheating to 150° C. for 8 minutes, and then continuing to heat to 250° C. and sintering under a pressure of 5 MPa for 15 minutes.

[0051] Beneficial effects:

[0052] A bionic honeycomb substrate for power device packaging has a patterned micro-nano dual-scale structure. It can be used as a substrate during power device packaging and can improve the connection strength of the interconnect structure. The substrate is prepared using an ultrafast laser processing system. This method has high processing efficiency, high processing repeatability, simple process, and no subsequent costs. The substrate can be used as a substrate in power device packaging. The designed bionic honeycomb structure is a densely packed pattern that is stable and isotropic. The micron-scale grooves and micro-cone arrays increase the interconnect area and can improve the connection strength. The nanoscale particle structure significantly increases the surface energy of the substrate, providing additional energy for the interconnection and making the connection between atoms more complete. Therefore, the bionic honeycomb substrate can significantly improve the connection strength of sintered silver during power device packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 This is a surface photo and detail diagram of the bionic honeycomb substrate of the present invention;

[0055] Figure 2 Schematic diagram of the structure of the ultrafast laser processing system used in the present invention;

[0056] Figure 3 is a cross-sectional view of an interconnect structure formed by the present invention;

[0057] Figure 4 Schematic diagram of the shear strength of the interconnection structure formed in the embodiment of the present invention and the comparative example;

[0058] Figure 5 This is a schematic diagram of a single regular hexagon among the regular hexagons densely packed on the surface of the bionic honeycomb substrate of the present invention.

[0059] Explanation of the reference numerals: 1- picosecond laser, 2- mirror assembly, 3- 3× beam expander, 4- 1 / 4λ wave plate, 5- CCD, 6- dichroic mirror, 7- scanning galvanometer, 8- focusing field lens, 9- sample, 10- translation stage. DETAILED DESCRIPTION

[0060] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0061] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0062] In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] Example 1: Preparation and Application of a Bionic Honeycomb Substrate for Power Device Packaging

[0064] 1. Cu substrate preparation: Use wire cutting to make a square copper pad with a size of 10 mm × 10 mm × 1 mm;

[0065] 2. Place a Cu sheet with a purity greater than 99.99wt.% and a size of 10mm×10mm×1mm in a prepared 30% HNO3 aqueous solution for a few minutes to remove oxides and contaminants on the surface of the Cu substrate. Then, place it in acetone for further ultrasonic cleaning. After cleaning, dry it and use sandpaper to polish it to ensure that the oxide layer is completely removed and the connection surface is level. After grinding, polish it and set aside.

[0066] 3. Use an ultrafast laser processing system to construct microstructures on the substrate surface. The scanning path is a bionic honeycomb pattern. The scanning pitch is set to 30 μm, the number of scans is 20, the laser power is 40 W, the laser frequency is 400 kHz, and the scanning speed is 3 m / s. The microstructures with a spacing of 30 μm and a depth of 20 μm are constructed on the substrate surface.

[0067] 4. Use an ultrafast laser processing system to in-situ deposit nanoscale structures on the surface of a bionic honeycomb substrate with a microstructure. Set the scanning spacing to 25μm, the laser power to 30W, the laser frequency to 400kHz, and the scanning speed to 50mm / s. Scan once. The laser excites nanoparticles from the Cu substrate and deposits them on the surface. The surface is filled with Cu nanoparticles, and a bionic honeycomb Cu substrate with a surface micro-nano dual-scale structure is prepared. Figure 1 As shown;

[0068] 5. Soak the bionic honeycomb Cu substrate with micro-nano dual-scale in a prepared 30% HNO3 aqueous solution for a few minutes to remove oxides and contaminants on the surface of the Cu substrate. Then, ultrasonically clean it in acetone and dry it after cleaning.

[0069] 6. Place the mask on the Cu substrate. There is a square hole in the middle of the mask that is the same size as the chip. The size is 5mm×5mm and the thickness of the mask is 100um. Apply a certain amount of nano-Ag solder paste on the mask. Use a scraper to scrape the solder paste flat and remove the mask.

[0070] 7. Gently place the Ag-plated SiC block on the nanosilver solder paste, with a size of 5 mm × 5 mm × 0.5 mm;

[0071] 8. Place the structure on a hot press sintering machine for sintering at a heating rate of 5°C / min, preheat to 150°C for 8 minutes, continue heating to 250°C and sintering at 5MPa for 15 minutes, and air cool to obtain interconnected solder joints with surface micro-nano structures on the substrate;

[0072] 9. Take the interconnection solder joint directly out of the sintering machine and perform shear strength test. The shear height is 50μm and the shear speed is 5μm / s. The shear strength is significantly improved. Figure 4 shown.

[0073] Example 2: Preparation and Application of a Bionic Honeycomb Substrate for Power Device Packaging

[0074] 1. Cu substrate preparation: Use wire cutting to make a square copper pad with a size of 10 mm × 10 mm × 1 mm;

[0075] 2. Place a Cu sheet with a purity greater than 99.99wt.% and a size of 10mm×10mm×1mm in a prepared 30% HNO3 aqueous solution for a few minutes to remove oxides and contaminants on the surface of the Cu substrate. Then, place it in acetone for further ultrasonic cleaning. After cleaning, dry it and use sandpaper to polish it to ensure that the oxide layer is completely removed and the connection surface is level. After grinding, polish it and set aside.

[0076] 3. Use an ultrafast laser processing system to construct microstructures on the substrate surface. The scanning path is a bionic honeycomb pattern. The scanning pitch is set to 30 μm, the number of scans is 40, the laser power is 25 W, the laser frequency is 100 kHz, and the scanning speed is 3 m / s. The microstructures with a spacing of 30 μm and a depth of 20 μm are constructed on the substrate surface.

[0077] 4. An ultrafast laser processing system was used to in-situ deposit nanoscale structures on the surface of a bionic honeycomb substrate with a microstructure. The scanning spacing was set to 25 μm, the laser power was 20 W, the laser frequency was 200 kHz, and the scanning speed was 30 mm / s. After one scan, the laser excited nanoparticles from the Cu substrate and deposited them on the surface. The surface was filled with Cu nanoparticles, thus preparing a bionic honeycomb Cu substrate with a surface micro-nano dual-scale structure.

[0078] 5. Soak the bionic honeycomb Cu substrate with micro-nano dual-scale in a prepared 30% HNO3 aqueous solution for a few minutes to remove oxides and contaminants on the surface of the Cu substrate. Then, ultrasonically clean it in acetone and dry it after cleaning.

[0079] 6. Place the mask on the Cu substrate. There is a square hole in the middle of the mask that is the same size as the chip. The size is 5mm×5mm and the thickness of the mask is 100um. Apply a certain amount of nano-Ag solder paste on the mask. Use a scraper to scrape the solder paste flat and remove the mask.

[0080] 7. Gently place the Ag-plated SiC block on the nanosilver solder paste, with a size of 5mm×5mm×1mm;

[0081] 8. Place the structure on a hot press sintering machine for sintering at a heating rate of 5°C / min, preheat to 150°C for 8 minutes, continue heating to 250°C and sintering at 5MPa for 15 minutes, and air cool to obtain interconnected solder joints with surface micro-nano structures on the substrate;

[0082] 9. Take the interconnect solder joint directly out of the sintering machine and perform a shear strength test with a shear height of 50 μm and a shear speed of 5 μm / s.

[0083] Comparative Example 1

[0084] 1. Cu substrate preparation: Use wire cutting to make a square copper pad with a size of 10 mm × 10 mm × 1 mm;

[0085] 2. Place a Cu sheet with a purity greater than 99.99wt.% and a size of 10mm×10mm×1mm in a prepared 30% HNO3 aqueous solution for a few minutes to remove oxides and contaminants on the surface of the Cu substrate. Then, place it in acetone for further ultrasonic cleaning. After cleaning, dry it and use sandpaper to polish it to ensure that the oxide layer is completely removed and the connection surface is level. After grinding, polish it and set aside.

[0086] 3. Place the mask on the Cu substrate. There is a square hole in the middle of the mask that is the same size as the chip, with a size of 5mm×5mm and a thickness of 100um. Apply a certain amount of nano-Ag solder paste on the mask, use a scraper to scrape the solder paste flat, and remove the mask.

[0087] 4. Gently place the Ag-plated SiC block on the nanosilver solder paste, with a size of 5mm×5mm×0.5mm;

[0088] 5. Place the structure on a hot press sintering machine for sintering. The heating rate of the sintering machine is 5°C / min. Heat to 150°C for preheating for 8 minutes, continue heating to 250°C and pressurize at 5MPa for sintering for 15 minutes. Air-cooling is performed to obtain interconnected solder joints with surface micro-nano structures on the substrate.

[0089] 6. Take this interconnect solder joint out directly from the sintering machine and conduct shear strength test. The shear height is 50μm and the shear speed is 5μm / s. The shear strength is poor. Figure 4 shown.

[0090] Comparative Example 2

[0091] 1. Cu substrate preparation: Use wire cutting to make a square copper pad with a size of 10 mm × 10 mm × 1 mm;

[0092] 2. Place a Cu sheet with a purity greater than 99.99wt.% and a size of 10mm×10mm×1mm in a prepared 30% HNO3 aqueous solution for a few minutes to remove oxides and contaminants on the surface of the Cu substrate. Then, place it in acetone for further ultrasonic cleaning. After cleaning, dry it and use sandpaper to polish it to ensure that the oxide layer is completely removed and the connection surface is level. After grinding, polish it and set aside.

[0093] 3. Use an ultrafast laser processing system to construct microstructures on the substrate surface. The scanning path is parallel and equidistant straight lines. The scanning pitch is set to 30 μm, the number of scans is 20, the laser power is 40 W, the laser frequency is 400 kHz, and the scanning speed is 3 m / s. A micro-groove structure with a spacing of 30 μm and a depth of 20 μm is constructed on the substrate surface.

[0094] 4. Soak the Cu substrate with microgrooves in a prepared 30% HNO3 aqueous solution for a few minutes to remove surface oxides and contaminants. Then, ultrasonically clean the substrate in acetone and dry it.

[0095] 5. Place the mask on the Cu substrate. There is a square hole in the middle of the mask that is the same size as the chip. The size is 5mm×5mm and the thickness of the mask is 100um. Apply a certain amount of nano-Ag solder paste on the mask. Use a scraper to scrape the solder paste flat and remove the mask.

[0096] 6. Gently place the Ag-plated SiC block on the nanosilver solder paste, with a size of 5 mm × 5 mm × 0.5 mm;

[0097] 7. Place the structure on a hot press sintering machine for sintering at a heating rate of 5°C / min, preheat to 150°C for 8 minutes, continue heating to 250°C and sintering at 5MPa for 15 minutes, and air cool to obtain interconnected solder joints with surface micro-nano structures on the substrate;

[0098] 8. Take the interconnect solder joint out of the sintering machine directly and perform shear strength test. The shear height is 50μm and the shear speed is 5μm / s. First, shear along the groove direction and then perpendicular to the groove direction. The shear strength is improved but not obvious. There are also differences in strength in different directions. Figure 4 shown.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bionic honeycomb substrate for power device packaging, characterized in that: Its surface has a bionic honeycomb patterned dual-scale micro-nano structure, including: A honeycomb pattern structure composed of micron-scale structures: densely packed regular hexagons with a side length of 1.5-1.7 mm. There is a circle with a diameter of 1 mm in the center of the regular hexagon. The interior of the circle is filled with a micro-cone array with a spacing of 30-40 μm and a height of 40-50 μm. The rest of the circle is filled with annular micro-grooves with a spacing of 30-40 μm and a depth of 20-50 μm. Nanoscale structure: Nanoparticles attached to the entire substrate surface, with a particle size of 50-300nm.

2. The method for preparing the bionic honeycomb substrate for power device packaging according to claim 1, characterized in that: The following steps are involved: Step 1: Grind and polish the Cu substrate; Step 2: Using an ultrafast laser processing system, patterned micron-scale structures are prepared by rapid scanning; Step 3: The patterned micron-scale structure surface completed in step 2 is constructed into a nanoscale structure using an ultrafast laser processing system; Step 4: pickling the substrate with the micro-nanostructured surface prepared in step 3, ultrasonically cleaning it after pickling, drying it, and setting it aside.

3. The preparation method according to claim 2, characterized in that The laser scanning path in step 2 is the same as the honeycomb pattern structure of the substrate.

4. The preparation method according to claim 2, characterized in that The specific process of step 3 is to in-situ deposit nanoparticles on the substrate surface to construct a nanoscale structure by controlling the scanning speed.

5. The preparation method according to claim 2, characterized in that Before polishing the Cu substrate in step 1, the Cu substrate is immersed in a prepared 30% HNO3 aqueous solution for a few minutes to remove oxides and contaminants on the surface of the Cu substrate, and then placed in acetone for further ultrasonic cleaning. After cleaning, it is dried and polished with sandpaper to ensure that the oxide layer is completely removed and the connection surface is level.

6. The preparation method according to claim 2, characterized in that The ultrafast laser processing system comprises: Ultrafast laser, used to emit ultrafast laser as a laser source for laser processing; A reflector assembly, used to refract the ultrafast laser so that it can be collimated and directed to a predetermined position; Beam shaping, including beam expanders and wave plates, to adjust the size and polarization direction of the light spot; CCD, used to observe the laser status and beam quality; Scanning galvanometer, which drives the internal reflective mirror to move through the movement of the motor, used for beam movement; Focusing field lens, which focuses the laser on the sample surface and increases the power density; In addition, there is a laser workstation and a control card to control the laser emission and the movement of the galvanometer.

7. The preparation method according to claim 6, characterized in that The ultrafast laser is a femtosecond laser or a picosecond laser.

8. The use of the bionic honeycomb substrate for power device packaging according to claim 1, characterized in that: As the substrate for power device packaging, nanosilver is used for interconnection. The process is as follows: Step 21: Clean the bionic honeycomb substrate for power device packaging, cover it with a mask, and apply nano-silver solder paste; Step 22: Let it sit for a while, then use tweezers to hold the edge of the mask and lift it vertically upwards; Step 23: Gently place the chip on the nanosilver solder paste, ensuring that the entire chip is on top of the solder paste; Step 24: Place the structure obtained in step 23 into a hot pressing sintering machine for hot pressing and sintering, followed by air cooling; Step 25: Perform a shear test on the interconnection structure obtained in step 24 to determine the effect of the surface micro-nanostructure on enhancing the connection strength.

9. The use of the bionic honeycomb substrate for power device packaging according to claim 8, characterized in that: The power device package uses a bionic honeycomb substrate with micro-nano dual scales for interconnection to improve shear strength.

10. The use of the bionic honeycomb substrate for power device packaging according to claim 8, characterized in that: In step 24, the heating rate of the sintering machine is 5° C. / min, and the sintering machine is heated to 150° C. for preheating for 8 minutes, and then heated to 250° C. and sintered under a pressure of 5 MPa for 15 minutes.

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