Copper paste for power device packaging and its preparation and chip mounting method

Abstract

This invention provides a copper paste for power device packaging and its preparation and chip mounting method. The copper paste for power device packaging of this invention comprises the following raw materials by mass content: 78-88% copper nanoparticles coated with corrosion inhibitor and 12-22% organic solvent system; wherein the organic solvent system comprises the following components by mass content: 0.5-2% dispersant, 1-3% antioxidant, 1-3% binder, and 92-97.5% solvent. The copper paste for power device packaging of this invention enables room temperature chip mounting before the drying step, effectively avoiding problems such as copper oxidation encountered during high-temperature chip mounting; simultaneously, the mounted structure exhibits uniform internal structure after the drying step, free from cracks, holes, etc., effectively preventing defects and possessing high strength; furthermore, the dried structure exhibits uniform structure after sintering, free from obvious defects, and can well meet actual production requirements.

Description

Technical Field

[0001] This invention relates to the field of high-performance power device packaging technology, and in particular to a copper paste for power device packaging and its preparation and chip mounting method. Background Technology

[0002] Third-generation wide-bandgap semiconductors have higher operating junction temperatures, maintaining good performance even above 350°C. To maximize their performance, higher demands are placed on packaging materials, requiring interconnect materials that can operate at low temperatures and high temperatures. Due to their unique size effect, nanoscale metal particles have been widely studied and applied. Compared to silver nanoparticles, copper nanoparticles have lower costs and better resistance to electrochemical migration, gradually becoming a research focus.

[0003] In practical applications of packaged interconnect structures, chip mounting is required before sintering. This involves attaching the chip to a sintered copper paste-substrate structure under certain conditions to ensure sufficient strength after mounting and prevent relative displacement between the chip and the substrate during sintering. However, current chip mounting processes typically require heating both the pick-up tip and the substrate at temperatures exceeding 100°C. These high temperatures can cause copper oxidation, leading to a decrease in subsequent sintering performance and electrical and thermal conductivity. Furthermore, the equipment used for high-temperature chip mounting is expensive, increasing production costs. Therefore, there is an urgent need for a room-temperature chip mounting process and a subsequent drying and sintering process.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a copper paste for power device packaging and its preparation and chip mounting method. This copper paste for power device packaging can complete room temperature chip mounting before the drying step, effectively avoiding problems such as copper oxidation that are encountered when chip mounting needs to be carried out at high temperatures.

[0006] This invention provides a copper paste for power device packaging, comprising the following raw materials by mass: 78-88% copper nanoparticles coated with corrosion inhibitor and 12-22% organic solvent system; wherein the organic solvent system comprises the following components by mass: 0.5-2% dispersant, 1-3% antioxidant, 1-3% binder and 92-97.5% solvent.

[0007] Preferably, the copper paste for power device packaging of the present invention comprises the following raw materials in the following mass percentages: 82-84% of corrosion inhibitor-coated nano-copper particles and 16-18% of an organic solvent system; wherein the organic solvent system comprises the following components in the following mass percentages: 0.5-1% of a dispersant, 1-2% of an antioxidant, 1.5-2% of a binder and 95-97% of a solvent.

[0008] In this invention, the corrosion inhibitor-coated copper nanoparticles are coated with corrosion inhibitor on the surface of the copper nanoparticles using a high-speed airflow impact method; specifically, the morphology of the copper nanoparticles is flake-shaped or spherical; the particle size of the copper nanoparticles is 100-1000nm, preferably 300-800nm, more preferably 400-800nm, for example 400nm, 500nm, 600nm, 800nm.

[0009] The corrosion inhibitor is selected from at least one of α-hydroxy acids and carboxylic acids, preferably at least one of citric acid, malic acid, lactic acid, tartaric acid and gluconic acid, and more preferably at least one of citric acid, malic acid and lactic acid.

[0010] The mass ratio of corrosion inhibitor to nano-copper particles is (95-99.5):(0.5-5).

[0011] The dispersant is selected from at least one of n-decaol, dodecaol, acrylic acid and isopropionic acid, preferably n-decaol or acrylic acid.

[0012] The antioxidant is selected from at least one of monoethanolamine, propanolamine and isopropanolamine, preferably propanolamine or isopropanolamine.

[0013] The binder is selected from at least one of polyvinyl alcohol, polymethyl methacrylate, methylcellulose and ethylcellulose, preferably ethylcellulose or methylcellulose.

[0014] The solvent is selected from at least one of alcoholic organic compounds, preferably at least one of ethanol, ethylene glycol, propylene glycol, glycerol, n-butanol, diethylene glycol, acetone alcohol and polyethylene glycol, more preferably multiples of ethylene glycol, propylene glycol, n-butanol and diethylene glycol.

[0015] The present invention also provides a method for preparing the copper paste for packaging the above-mentioned power devices, comprising the following steps:

[0016] S1: Pre-treat the copper nanoparticles to obtain pre-treated copper nanoparticles;

[0017] S2: The corrosion inhibitor is coated on the surface of the pretreated nano-copper particles by high-speed airflow impact method to obtain corrosion inhibitor coated nano-copper particles.

[0018] S3: Mix the nano-copper particles coated with dispersant and corrosion inhibitor evenly, then mix, stir and pass through a mixture of antioxidant, binder and solvent to obtain copper paste for power device packaging.

[0019] Specifically, step S1 includes:

[0020] S11: After mixing the nano-copper particles with acid, ultrasonic treatment is performed, and the supernatant is removed by centrifugation.

[0021] S12: Add ethanol and sonicate, centrifuge to remove the supernatant, and dry under nitrogen atmosphere to obtain pretreated nano-copper particles.

[0022] In step S11, the acid solution is at least one of dilute sulfuric acid solution and lactic acid solution, and the ultrasonic treatment time is 5-30 min, for example 10-20 min; in step S12, the ultrasonic treatment time is 5-20 min, for example 10-20 min, and the drying temperature is 30-70℃, for example 40-60℃.

[0023] Step S2 includes: using a high-speed airflow impact method to atomize the corrosion inhibitor and continuously blow it into a coating device containing pretreated nano-copper particles, so that the corrosion inhibitor coats the surface of the pretreated nano-copper particles, and obtains corrosion inhibitor-coated nano-copper particles; wherein, the high-speed airflow impact conditions include: rotation speed of 5000-12000 r / min, and continuous blowing time of 5-30 min.

[0024] In step S3, the ethanol solution of the dispersant is mixed with the nano-copper particles coated with the corrosion inhibitor and sonicated for 10-30 minutes to ensure particle dispersion; the antioxidant, binder and solvent are weighed and sonicated according to the proportion, and then magnetically stirred for 1-3 hours to ensure uniform solvent mixing; the stirring time is 30-50 minutes; the paste is passed through a three-roll mill for 15-35 minutes to ensure uniform paste.

[0025] The present invention also provides the application of the above-mentioned copper paste for power device packaging in power device packaging.

[0026] The present invention also provides a method for mounting copper paste for power device packaging, comprising the following steps:

[0027] a) The copper paste for packaging the power devices is uniformly coated onto the connection surface of the substrate by stencil printing to obtain a stacked structure of solder paste and substrate.

[0028] b) Place the stacked structure of solder paste and substrate on a room temperature placement stage, and use a pick-and-place machine to attach the chip connection surface to the solder paste layer of the stacked structure to obtain the chip-solder paste-substrate stacked structure.

[0029] c) The stacked structure of chip-solder paste-substrate is placed in a drying oven and dried to obtain a dried structure;

[0030] d) The dried structure is sintered in an inert or reducing atmosphere to obtain a power device packaging structure.

[0031] Specifically, in step a), the coating thickness is 50-200 μm; in step b), the pressure applied when the chip mounter picks up the die is 0.3-5 N; in step c), the drying conditions include: pressureless drying at 110-160℃ for 10-30 min; in step d), the sintering conditions include: sintering temperature of 200-300℃, sintering pressure of 5-25 MPa, and sintering time of 1-15 min.

[0032] The implementation of this invention has at least the following advantages:

[0033] This invention employs a corrosion inhibitor to coat nano-copper particles and uses a specific organic solvent system to prepare copper paste for power device packaging. In practical applications, this copper paste allows for chip mounting at room temperature before the drying step. The organic matter almost completely volatilizes during the drying process, ensuring the initial formation of a sintered structure after drying. The overall structure maintains a certain strength after drying, meeting production requirements. Simultaneously, the added trace amounts of binder prevent internal defects such as residual pores and cracks caused by the volatilization of organic matter. This effectively solves the problems of copper oxidation and high costs associated with heating the substrate and pick-up nozzle to over 100°C for current chip mounting methods, as well as the increased cost due to expensive pre-sintering equipment. The mounted structure exhibits uniform internal structure after drying, free from cracks and pores, effectively avoiding defects and possessing high strength. Furthermore, the dried structure exhibits uniform structure and no obvious defects after sintering, perfectly meeting actual production needs. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 A schematic diagram of the preparation process of copper paste for power device packaging;

[0036] Figure 2 A schematic diagram of the chip mounting process;

[0037] Figure 3 Structural strength diagram of the chip after mounting and drying;

[0038] Figure 4 Ultrasonic scanning image of the structure after chip mounting and sintering;

[0039] Figure 5 The structural strength diagram of the chip after mounting and sintering. Detailed Implementation

[0040] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] 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.

[0043] Example 1

[0044] This embodiment provides a copper paste for power device packaging, composed of the following raw materials by mass percentage: 82% copper nanoparticles coated with corrosion inhibitor, and 18% organic solvent system; wherein:

[0045] The average particle size of the copper nanoparticles is about 500 nm, and they are spherical in shape.

[0046] The corrosion inhibitor is citric acid;

[0047] The organic solvent system consists of the following raw materials by mass percentage: dispersant 0.5%, antioxidant 1%, binder 1.5%, and solvent 97%; wherein:

[0048] The dispersant is n-decaol, the antioxidant is isopropanolamine, the binder is ethyl cellulose, and the solvent consists of ethylene glycol, propylene glycol, and n-butanol, with a mass ratio of 6:1:1.

[0049] This embodiment also provides a method for preparing the copper paste for power device packaging described above, the preparation process as follows: Figure 1 As shown, it includes the following steps:

[0050] 1) Mix the nano-copper particles with dilute sulfuric acid, sonicate for 20 min, centrifuge to remove the supernatant, add ethanol, sonicate for 10 min, centrifuge to remove the supernatant;

[0051] 2) Place the copper nanoparticles obtained in step 1) into a drying oven and dry them at 60°C under a nitrogen atmosphere. Cool them down to room temperature and remove them to ensure complete evaporation of ethanol, thus obtaining pretreated copper nanoparticles.

[0052] 3) Citric acid is atomized and blown into a coating device containing the pretreated nano-copper particles obtained in step 2). The coating is carried out by high-speed airflow impact method. The high-speed airflow impact conditions include: rotation speed of 7500 r / min, continuous blowing for 20 min, and controlling the mass ratio of corrosion inhibitor citric acid to nano-copper particles to be 99:1 to ensure that the nano-copper particles are completely coated and obtain corrosion inhibitor coated nano-copper particles.

[0053] 4) Mix the ethanol solution of n-decaol with the corrosion inhibitor-coated copper nanoparticles and sonicate for 30 minutes to ensure particle dispersion. Centrifuge to remove the supernatant and place in a drying oven to dry under a nitrogen atmosphere.

[0054] 5) Weigh isopropanolamine, ethyl cellulose, ethylene glycol, propylene glycol, and n-butanol according to the specified proportions and mix them ultrasonically. After mixing, stir magnetically for 3 hours to ensure that the solvent is mixed evenly.

[0055] 6) Mix the mixture obtained in step 5) with the copper nanoparticles coated with corrosion inhibitor and dispersant obtained in step 4), and stir for 50 minutes to obtain copper paste.

[0056] 7) Pass the copper paste obtained in step 6) through a three-roll mill for 35 minutes to ensure uniformity of the paste and obtain copper paste for power device packaging.

[0057] The copper paste for power device packaging prepared above is applied to the packaging interconnect structure of wide-bandgap semiconductor devices.

[0058] This embodiment also provides a chip mounting and sintering method based on the above-mentioned copper paste for power device packaging, wherein a schematic diagram of the chip mounting and drying process is shown below. Figure 2 As shown, the substrate for the interconnect structure is a bare copper substrate, and the chip is a silicon carbide wafer; the chip area is 5×6mm. 2 The substrate area is 20×30mm. 2 The specific steps are as follows:

[0059] 1) Copper paste is uniformly coated onto the substrate interface by stencil printing, with a coating thickness of about 80μm;

[0060] 2) Place the copper paste-substrate stack structure obtained in step 1) on a room temperature mounting stage, pick up the chip using a chip mounter, and apply a force of 0.9N to attach the chip connection surface to the copper paste layer.

[0061] 3) Place the stacked structure of chip-copper paste-substrate obtained in step 2) in a drying oven, heat it to 140°C, keep it at that temperature for 15 minutes, and dry it without pressure;

[0062] 4) Place the dried chip-copper paste-substrate structure obtained in step 3) into a pressure sintering apparatus.

[0063] 5) Maintain an inert or reducing atmosphere and sinter at 250℃ and 20MPa for 3 minutes to obtain the power device packaging structure.

[0064] After testing, the copper paste for power device packaging prepared in this embodiment can successfully complete the chip mounting process at room temperature. The structure after chip mounting and drying has a certain strength, and the strength after chip mounting and drying at different temperatures is as follows: Figure 3 As shown in the figure; the results indicate that within the operating temperature range, the dried structure exhibits high strength, exceeding 60 MPa, which meets the application requirements.

[0065] The structure is sintered under pressure within a specified temperature, and then subjected to ultrasonic non-destructive scanning. The scanned images are as follows: Figure 4 As shown in the figure; the results indicate that the sintered structure has no obvious defects, is very uniform, and can meet the application requirements.

[0066] Shear tests were conducted on the stacked structures sintered at different temperatures, and the strength changed with temperature as follows: Figure 5 As shown in the figure; the results indicate that the strength of the sintered stacked structure exceeds 50 MPa, which can well meet the actual production requirements.

[0067] Example 2

[0068] This embodiment provides a copper paste for power device packaging, composed of the following raw materials by weight percentage: 84% nano-copper powder coated with corrosion inhibitor, and 16% organic solvent system. Wherein:

[0069] The average particle size of the copper nanoparticles is about 800 nm, and they are plate-like in morphology.

[0070] The corrosion inhibitor is composed of malic acid and lactic acid, with a mass ratio of malic acid to lactic acid of 1:1.

[0071] The organic solvent system consists of the following raw materials by mass percentage: dispersant 1%, antioxidant 2%, binder 2%, and organic solvent 95%; wherein:

[0072] The dispersant is acrylic acid, the antioxidant is propanolamine, the binder is methylcellulose, and the solvent consists of propylene glycol, n-butanol, and diethylene glycol in a mass ratio of 2:1:4.

[0073] This embodiment also provides a method for preparing the copper paste for power device packaging, including the following steps:

[0074] 1) Mix the nano-copper particles with lactic acid, sonicate for 10 min, centrifuge to remove the supernatant, add ethanol, sonicate for 20 min, centrifuge to remove the supernatant;

[0075] 2) Place the copper nanoparticles obtained in step 1) into a drying oven and dry them at 40°C under a nitrogen atmosphere. Cool them down to room temperature and remove them to ensure complete evaporation of ethanol, thus obtaining pretreated copper nanoparticles.

[0076] 3) Atomize malic acid and lactic acid and blow them into a coating device containing the pretreated nano-copper particles obtained in step 2). Coating is carried out using a high-speed airflow impact method. The high-speed airflow impact conditions include: rotation speed of 9000 r / min, continuous blowing for 15 min, and controlling the ratio of the total mass of the corrosion inhibitor malic acid and lactic acid to the mass of the nano-copper particles to be 98.5:1.5 to ensure that the nano-copper particles are completely coated and obtain corrosion inhibitor-coated nano-copper particles.

[0077] 4) Mix the ethanol solution of acrylic acid with the corrosion inhibitor-coated nano-copper particles and sonicate for 10 minutes to ensure particle dispersion. Centrifuge to remove the supernatant and place in a drying oven to dry in a nitrogen atmosphere.

[0078] 5) Weigh propanolamine, methylcellulose, propylene glycol, n-butanol, and diethylene glycol according to the specified proportions and mix them ultrasonically. After mixing, stir magnetically for 1 hour to ensure that the solvent is mixed evenly.

[0079] 6) Mix the mixture obtained in step 5) with the copper nanoparticles coated with corrosion inhibitor and dispersant obtained in step 4), and stir for 30 minutes using a mixer;

[0080] 7) Pass the copper paste obtained in step 6) through a three-roll mill for 15 minutes to ensure uniformity of the paste and obtain copper paste for power device packaging.

[0081] The copper paste for power device packaging prepared above is applied to the packaging interconnect structure of wide-bandgap semiconductor devices.

[0082] This embodiment also provides a chip mounting and sintering method based on the above-mentioned copper paste for power device packaging, wherein a schematic diagram of the chip mounting and drying process is shown below. Figure 2 As shown, the substrate for the interconnect structure is a bare copper substrate, and the chip is a silicon carbide wafer; the chip area is 5×6mm. 2 The substrate area is 20×30mm. 2 The specific steps are as follows:

[0083] 1) Copper paste is uniformly coated onto the substrate interface by stencil printing, with a coating thickness of about 100μm.

[0084] 2) Place the copper paste-substrate stack structure obtained in step 1) on a room temperature mounting stage, use a pick-and-place machine to pick up the chip, and apply a force of 2N to attach the chip connection surface to the copper paste layer.

[0085] 3) Place the stacked structure of chip-copper paste-substrate obtained in step 2) in a drying oven, heat it to 120°C, keep it at that temperature for 10 minutes, and dry it without pressure;

[0086] 4) Place the dried chip-copper paste-substrate structure obtained in step 3) into a pressure sintering apparatus.

[0087] 5) Maintain an inert or reducing atmosphere and sinter at 260℃ and 10MPa for 5 minutes to obtain the power device packaging structure.

[0088] After testing, the copper paste for power device packaging prepared in this embodiment can successfully complete the chip mounting process at room temperature. The structure after drying exhibits a certain strength, with the strength exceeding 1 MPa, which is high and meets the application requirements. Pressure sintering was performed within the specified temperature range, and ultrasonic non-destructive scanning of the sintered structure revealed no obvious defects, confirming its suitability for use. Furthermore, shear tests were conducted on the stacked structures sintered at different temperatures, and the strength consistently exceeded 55 MPa, indicating that the stacked structure can well meet actual production needs.

[0089] Comparative Example 1

[0090] This comparative example provides a sintering copper paste, except that the solvent in the organic solvent system is composed of polyethylene glycol and polyethylene glycol, with a mass ratio of polyethylene glycol to polyethylene glycol of 1:1, and the rest is basically the same as in Example 1.

[0091] Testing revealed that after the chip mounting and drying process, the overall structural strength was low, below 0.6 MPa, due to the inability of organic matter to evaporate in time. Furthermore, during the pressure sintering process, the rapid temperature rise resulted in uneven and incomplete evaporation of organic matter, leading to large-area defects observed during ultrasonic non-destructive scanning. Therefore, the sintering-type copper paste in this comparative example cannot be applied to actual production and does not meet the usage requirements.

[0092] Comparative Example 2

[0093] This comparative example provides a sintering copper paste, which is basically the same as Example 1 except that no binder is added to the organic solvent system and the mass percentage of the organic solvent is 98.5%.

[0094] Testing showed that after chip mounting and drying, the overall structure possessed sufficient strength to meet usage requirements. Under pressure sintering at a specified temperature, the strength reached approximately 50 MPa. Ultrasonic non-destructive scanning of the sintered structure revealed internal cracks, suggesting that these defects reduced strength and severely impacted subsequent electrical and thermal conductivity, rendering the structure unsuitable for practical production.

[0095] In summary, this invention uses a corrosion inhibitor to coat the nano-copper particles and employs a specific organic solvent system, which enables chip mounting to be completed well before the drying step. The mounted structure exhibits high strength after drying, meeting production requirements. Furthermore, the sintered structure has a uniform microstructure, no obvious defects, and strength exceeding general usage requirements.

[0096] 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 copper paste for packaging power devices, characterized in that, It is made from the following raw materials by mass content: 78-88% copper nanoparticles coated with corrosion inhibitor and 12-22% organic solvent system; The organic solvent system comprises the following components by mass percentage: dispersant 0.5-2%, antioxidant 1-3%, binder 1-3%, and solvent 92-97.5%; the corrosion inhibitor-coated copper nanoparticles are coated with corrosion inhibitor on the surface of the copper nanoparticles using a high-speed airflow impact method, the particle size of the copper nanoparticles is 300-800 nm, the corrosion inhibitor is selected from at least one of citric acid, malic acid, and lactic acid, and the mass ratio of corrosion inhibitor to copper nanoparticles is (95-99.5):(0.5-5); the dispersant is n-decaol or acrylic acid; the antioxidant is propanolamine or isopropanolamine; the binder is ethyl cellulose or methyl cellulose; and the solvent is selected from multiple types of ethylene glycol, propylene glycol, n-butanol, and diethylene glycol.

2. The copper paste for power device packaging according to claim 1, characterized in that, The morphology of the nano-copper particles is plate-like or spherical.

3. The method for preparing copper paste for power device packaging according to claim 1 or 2, characterized in that, Includes the following steps: S1: Pre-treat the copper nanoparticles to obtain pre-treated copper nanoparticles; S2: The corrosion inhibitor is coated on the surface of the pretreated nano-copper particles by high-speed airflow impact method to obtain corrosion inhibitor coated nano-copper particles. S3: Mix the nano-copper particles coated with dispersant and corrosion inhibitor evenly, then mix, stir and pass through a mixture of antioxidant, binder and solvent to obtain copper paste for power device packaging.

4. The preparation method according to claim 3, characterized in that, Step S1 includes: S11: After mixing the nano-copper particles with acid, ultrasonic treatment is performed, and the supernatant is removed by centrifugation. S12: Add ethanol and sonicate, centrifuge to remove the supernatant, and dry under nitrogen atmosphere to obtain pretreated nano-copper particles.

5. The preparation method according to claim 4, characterized in that, In step S11, the acid solution is at least one of dilute sulfuric acid solution and lactic acid solution, and the ultrasonic treatment time is 5-30 min; in step S12, the ultrasonic treatment time is 5-20 min, and the drying temperature is 30-70 ℃.

6. The preparation method according to claim 3, characterized in that, Step S2 includes: using a high-speed airflow impact method to atomize the corrosion inhibitor and continuously blow it into a coating device containing pretreated nano-copper particles, so that the corrosion inhibitor coats the surface of the pretreated nano-copper particles, and obtains corrosion inhibitor-coated nano-copper particles; wherein, the high-speed airflow impact conditions include: rotation speed of 5000-12000 r / min, and continuous blowing time of 5-30 min.

7. The application of the copper paste for power device packaging as described in claim 1 or 2 in power device packaging.

8. A method for mounting copper paste for power device packaging, characterized in that, Includes the following steps: a) The copper paste for power device packaging as described in claim 1 or 2 is uniformly coated onto the connection surface of the substrate by stencil printing to obtain a solder paste-substrate stack structure. b) Place the solder paste-substrate stacked structure on a room temperature placement stage, and use a pick-and-place machine to attach the chip connection surface to the solder paste layer of the stacked structure to obtain the chip-solder paste-substrate stacked structure. c) The stacked structure of chip-solder paste-substrate is placed in a drying oven and dried to obtain a dried structure; d) The dried structure is sintered in an inert or reducing atmosphere to obtain a power device packaging structure.

9. The patching method according to claim 8, characterized in that, In step a), the coating thickness is 50-200 μm; in step b), the pressure applied when the chip mounter picks up the die is 0.3-5 N; in step c), the drying conditions include: drying without pressure at 110-160℃ for 10-30 min; in step d), the sintering conditions include: sintering temperature of 200-300 ℃, sintering pressure of 5-25 MPa, and sintering time of 1-15 min.

Images