A packaging method for a power diode

Abstract

The present invention relates to the technical field of electronic device packaging, and in particular to a packaging method for power diodes, comprising: step S1, pre-treating silica gel into a fluid state and adjusting its dynamic viscosity value to a preset range; step S2, adding fluid protective glue into a coating system for dispensing, and using a scraper to perform thinning operations and leveling operations to form a flexible packaging layer; step S3, judging whether the flexible packaging layer has defects and the specific types of defects, repairing the defects and adjusting the operating parameters of the coating system to obtain a glue-coated component; step S4, placing the glue-coated component in a curing chamber for heating and curing to obtain a packaged product; step S5, cutting and molding the packaged product to obtain a packaged power diode; the present invention uses the packaging method of the flexible packaging layer to control the overall thickness of the power diode to below 0.8 mm, while avoiding mechanical stress in the plastic sealing process and reducing the packaging defect rate.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic device packaging, and in particular to a packaging method for a power diode. Background Art

[0002] Power diodes are key components in circuit systems and are widely used in civilian products such as high-frequency inverters, digital products, generators, televisions, photovoltaics, and power supplies, as well as in military applications such as satellite receivers, advanced weapon control systems, and instrumentation equipment, including missiles and aircraft. Currently, during the power diode production process, the chip is typically packaged to prevent corrosion from airborne impurities that could degrade electrical performance, and to facilitate installation and transportation. Conventional power diode packaging typically utilizes plastic or metal encapsulation, which has a relatively thick encapsulation layer. In extremely compact applications such as PD (Power Delivery), PCB space is extremely precious. Surface-mount devices with a thickness of less than 2mm are generally preferred for ultra-thin PD fast charging. Chinese Patent Publication No. CN208336190U discloses an SMBF diode packaging structure and electronic device, including: a packaging shell, with the tail end of a first frame and the tail end of a second frame extending horizontally from both sides of the exterior of the packaging shell, respectively, and the remaining portions of the first frame and the second frame encapsulated inside the packaging shell, the first frame and the second frame being relatively parallel and arranged vertically, a chip structure being pressed between the parallel gaps of the first frame and the second frame, and the first frame and the chip structure being connected by a solder sheet.

[0003] It can be seen that the SMBF diode packaging structure and electronic equipment have the following problems: although the thickness of SMBF is about 50% thinner than the 2.25mm of ordinary flattened SMA and the 2.1mm of frame SMA, it is still packaged in plastic, making it difficult to further reduce its thickness under the existing process and unable to meet the current ultra-thin requirements. Summary of the Invention

[0004] To this end, the present invention provides a packaging method for a power diode, so as to overcome the problem of a thick packaging layer of the power diode in the prior art.

[0005] To achieve the above object, the present invention provides a method for packaging a power diode, comprising:

[0006] Step S1, pre-treating the silica gel into a fluid state and adjusting the dynamic viscosity value to within a preset range to obtain a fluid protective gel, and recording the current dynamic viscosity value of the fluid protective gel as a dynamic viscosity characteristic value;

[0007] Step S2: adding the fluid protective adhesive to a coating system, adjusting the single-point adhesive application parameters of the coating system according to the dynamic viscosity characteristic value, and performing a single-point adhesive application operation. Using a scraper, the fluid protective adhesive is thinned once by moving the scraper forward and then leveled once by moving the scraper backward to form a flexible encapsulation layer on the surface of the chip component array.

[0008] Step S3, detecting a change in the reflectivity of the flexible encapsulation layer through an image recognition system to determine whether the flexible encapsulation layer has defects and the specific type of defects, and adjusting the operating parameters of the coating system based on the location distribution and type of the defects; performing single-point repair according to the defect type to obtain a coated component;

[0009] Step S4, placing the glue coating component in a curing chamber, and adjusting the curing parameters of the curing chamber according to the dynamic viscosity characteristic quantity to cure the flexible packaging layer to obtain a packaging product;

[0010] Step S5: cutting and molding the packaged product, and performing an electrical performance test to obtain a packaged power diode.

[0011] Furthermore, the step S1 includes:

[0012] Step S11, allowing the silica gel to stand at a preset temperature;

[0013] Step S12, detecting the dynamic viscosity of the silica gel, and if the dynamic viscosity is not within a preset dynamic viscosity range, adding a diluent or a thickener to adjust the dynamic viscosity;

[0014] Step S13, repeating step S12, when the detected dynamic viscosity is within the preset dynamic viscosity range, recording the current dynamic viscosity value as the dynamic viscosity characteristic value;

[0015] Step S14: vacuum degassing the silica gel to obtain a fluid protective adhesive.

[0016] Furthermore, in the step S14, the vacuum degassing process adopts pulsed negative pressure control, wherein the negative pressure intensity, pulse frequency and degassing time are determined according to the dynamic viscosity characteristic value.

[0017] Furthermore, the step S2 includes:

[0018] Step S21, adding the fluid protective adhesive into the coating system, fixing a plurality of chip components on a fixture with an adjustable tilt angle to form a chip component array;

[0019] Step S22, calculating the single-point glue dispensing amount and glue dispensing speed of the coating system according to the dynamic viscosity characteristic value obtained in step S13;

[0020] Step S23, locating the position data of each chip component in the chip component array by an image recognition system to obtain the coordinates of the glue outlet of the coating system for each single-point glue application;

[0021] Step S24, moving the glue outlet of the coating system to the starting end of the chip assembly array, and performing a single-point glue application operation on the entire array of chip assemblies so that the fluid protective glue covers the upper surface and circumferential side surfaces of each chip;

[0022] Step S25, adjusting the tilt angle of the fixture to a preset tilt angle so that the gap formed between the upper frame and the lower frame of the chip assembly forms an angle with the horizontal plane, so that the fluid protective glue can infiltrate the gap under the action of gravity;

[0023] Step S26, restoring the angle of the fixture to the horizontal plane, moving the scraper of the coating system to the starting end of the chip assembly, and adjusting the height of the scraper according to the amount of glue applied at a single point;

[0024] Step S27, moving the scraper in the forward direction along the current column to thin the adhesive layer;

[0025] Step S28 , moving the scraper in the opposite direction along the same column to level the adhesive layer to form a flexible packaging layer.

[0026] Furthermore, in step S25, the preset inclination angle and the infiltration time are calculated based on the dynamic viscosity characteristic value, and the preset inclination angle and the infiltration time are positively correlated with the dynamic viscosity characteristic value.

[0027] Furthermore, in the step S26, after restoring the angle of the clamp to the horizontal plane, the clamp is vibrated for a preset vibration duration to eliminate the surface tension of the colloid, and the vibration duration is determined according to the dynamic viscosity characteristic value.

[0028] Furthermore, in step S28, when the scraper is moved in the reverse direction, the moving speed of the scraper is reduced to a preset proportion of the moving speed of the scraper when the scraper is moved in the forward direction, and the scraper angle is adjusted to axially deflect along the upper edge of the scraper so that the height of the scraper is lowered to a preset height, so as to apply shear force to level the adhesive layer.

[0029] Furthermore, step S3 includes:

[0030] Step S31, obtaining reflectivity change data of the flexible packaging layer of each chip component in the chip component array through detection by an image recognition system;

[0031] Step S32, performing a first-level screening of the flexible encapsulation layer based on the area ratio of high-reflectivity pixels to low-reflectivity pixels and the reflectivity gradient change rate in the reflectivity change data to determine whether the flexible encapsulation layer is qualified, and performing preliminary defect classification on unqualified flexible encapsulation layers;

[0032] Step S33: performing a second-level determination based on the area ratio of high-reflectivity pixels to low-reflectivity pixels in the reflectivity change data, the reflectivity gradient change rate, and the shape factor of the low-reflectivity pixel area to obtain a specific defect type of the unqualified flexible encapsulation layer;

[0033] Step S34, classifying and marking the position of the chip component where the flexible encapsulation layer is located according to the defect type, and adjusting the single-point adhesive dispensing parameters or correcting the thinning and leveling operation parameters based on the defect location distribution and defect type;

[0034] Step S35, performing corresponding repair operations on the flexible packaging layers of all the chip components with marked coordinates in sequence according to the classification marks;

[0035] Step S36, repeating steps S31 to S35 until all areas of the chip component array pass the integrity test to obtain a glue-coated component.

[0036] Furthermore, the step S4 includes:

[0037] Step S41, calculating parameters of the curing process according to the dynamic viscosity characteristic value obtained in step S13;

[0038] Step S42, placing the glue-coated component in a curing chamber and filling it with nitrogen to eliminate interference from oxygen;

[0039] Step S43, pre-curing the flexible packaging layer at a low temperature to eliminate bubbles in the glue and form a stable support structure;

[0040] Step S44, gradually increasing the curing temperature to perform primary curing on the silica gel;

[0041] Step S45, checking the thickness data of the cured flexible packaging layer through an image recognition system;

[0042] Step S46, comparing the thickness data with the target thickness to determine whether the thickness of the flexible encapsulation layer after curing is qualified;

[0043] Step S47, degumming the unqualified flexible encapsulation layer after curing, and re-gluing and curing the flexible encapsulation layer, while adjusting the parameters of the curing process to reduce the shrinkage rate of the silicone to improve the dimensional stability of the flexible encapsulation layer;

[0044] Step S48, repeating steps S45 to S47 until all the cured flexible packaging layers reach the target thickness, thereby obtaining a packaging product.

[0045] Furthermore, the parameters of the curing process include: pre-curing temperature, main curing time and heating rate; the pre-curing temperature is positively correlated with the dynamic viscosity characteristic quantity, and the main curing time and heating rate are negatively correlated with the dynamic viscosity characteristic quantity.

[0046] Compared with the existing technology, the beneficial effect of the present invention lies in the use of flexible packaging to replace the traditional plastic packaging process, and through the full process design of pretreatment, coating, testing, and curing, the process feasibility of the ultra-thin packaging layer is ensured, so that the thickness of the flexible packaging layer is less than 30μm, thereby controlling the overall thickness of the power diode to below 0.8mm. At the same time, the flexible packaging layer also avoids the mechanical stress caused by the plastic packaging process, and cooperates with closed-loop control based on multiple parameters such as dynamic viscosity, temperature, and reflectivity to reduce the packaging defect rate.

[0047] Furthermore, the present invention dynamically adjusts the negative pressure intensity during the vacuum degassing process based on the dynamic viscosity, thereby preventing high dynamic viscosity colloids from generating microcracks due to excessive negative pressure.

[0048] Furthermore, the present invention ensures the chip gap wetting rate and reduces the thickness fluctuation range of the adhesive layer through forward and reverse double coating and precise adjustment of the coating system position.

[0049] Furthermore, the present invention avoids the problem of low dynamic viscosity colloid excessively flowing due to gravity or high dynamic viscosity colloid being unable to fill the gap by adaptively adjusting the inclination angle of the fixture according to the dynamic viscosity.

[0050] Furthermore, the present invention eliminates colloid accumulation caused by forward coating and reduces the roughness of the adhesive layer surface through shear force trimming and glue output control.

[0051] Furthermore, the present invention eliminates the surface tension of the colloid by utilizing high-frequency vibration, thereby reducing the shrinkage of the edge and improving the coverage of the edge.

[0052] Furthermore, the present invention detects the coating area through the change of reflectivity, and through the three-level mechanism of coarse screening, fine judgment and adjustment, takes into account efficiency and accuracy, distinguishes the defect types, and accurately repairs the coating defects to prevent ineffective repairs or overall rework.

[0053] Furthermore, the present invention eliminates microbubbles that cannot be identified due to the resolution limit of industrial cameras through low-temperature pre-curing, and at the same time forms a stable support structure to avoid collapse caused by uncured bottom of the adhesive layer.

[0054] Furthermore, the present invention improves the uniformity of cross-linking by increasing the temperature of the main curing gradient and matching the dynamic viscosity characteristic of the silicone, avoids insufficient curing of high-viscosity colloids or excessive curing of low-viscosity colloids, improves the curing quality, and extends the thermal cycle life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Flowchart of the packaging method of the power diode of the present invention;

[0056] Figure 2 Flowchart of step S2 of the power diode packaging method of the present invention;

[0057] Figure 3 Flowchart of step S3 of the power diode packaging method of the present invention;

[0058] Figure 4 This is a schematic structural diagram of a chip assembly in an embodiment of a method for packaging a power diode of the present invention;

[0059] Figure 5 A cross-sectional view of a glue-coated component in an embodiment of a packaging method for a power diode of the present invention;

[0060] Figure 6 A three-dimensional diagram of a glue-coated component in an embodiment of a packaging method for a power diode of the present invention;

[0061] In the figure, 1-chip; 2-upper frame; 21-upper pin; 22-upper frame connection area; 23-stress release area; 3-lower frame; 31-lower pin; 32-lower electrode area; 4-connection frame; 41-connection area; 42-upper electrode area; 5-flexible packaging layer. DETAILED DESCRIPTION

[0062] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0063] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0064] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0065] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0066] See also Figures 4-6 As shown, it is a structural schematic diagram of the chip component in the embodiment of the packaging method of the power diode of the present invention, a cross-sectional view of the glue-coated component in the embodiment of the packaging method of the power diode of the present invention, and a three-dimensional view of the glue-coated component in the embodiment of the packaging method of the power diode of the present invention, including:

[0067] Chip 1, upper frame 2, lower frame 3, connecting frame 4 and flexible packaging layer 5, wherein,

[0068] The upper frame 2 is made of copper and includes upper pins 21 and an upper frame connection area 22 at both ends of the upper frame 2. An upwardly bent arc-shaped stress relief area 23 is provided between the lower pins 21 and the upper frame connection area 22 to provide the upper frame 2 with a certain stress relief capability and further reduce the thickness of the flexible packaging layer 5.

[0069] The lower frame 3 is made of copper and includes lower pins 31 and lower electrode areas 32 located at both ends of the lower frame 3;

[0070] The connecting frame 4 is made of copper and includes a connecting area 41 and an upper electrode area 42 located at both ends of the connecting frame 4. The upper electrode area 42 is higher than the connecting area 41, and the height change area is an arc-shaped transition.

[0071] The connecting area 41 is welded on the frame connecting area 22 through a solder paste layer, and the chip 3 is welded between the upper electrode area 42 and the lower electrode area 32 through a solder paste layer.

[0072] The flexible packaging layer 4 covers the upper surface of the chip 1 and the upper electrode area 42 , as well as the circumferential side surfaces of the chip 1 and the lower electrode area 32 not covered by the chip 1 ;

[0073] Preferably, in this embodiment, the width of the connecting frame 4 is smaller than that of the upper frame 2 , so as to reduce the width of the gap between the connecting frame 4 and the lower electrode area 32 , making it easier for the fluid curing adhesive to completely infiltrate the gap.

[0074] For more details, please refer to Figure 1 As shown, it is a flow chart of the packaging method of the power diode of the present invention, comprising:

[0075] Step S1, pre-treating the silica gel into a fluid state and adjusting the dynamic viscosity value to within a preset range to obtain a fluid protective gel, and recording the current dynamic viscosity value of the fluid protective gel as a dynamic viscosity characteristic value;

[0076] Step S2: adding the fluid protective adhesive to a coating system, adjusting the single-point adhesive application parameters of the coating system according to the dynamic viscosity characteristic value, and performing a single-point adhesive application operation. Using a scraper, the fluid protective adhesive is thinned once by moving the scraper forward and then leveled once by moving the scraper backward to form a flexible encapsulation layer on the surface of the chip component array.

[0077] Step S3, detecting a change in the reflectivity of the flexible encapsulation layer through an image recognition system to determine whether the flexible encapsulation layer has defects and the specific type of defects, and adjusting the operating parameters of the coating system based on the location distribution and type of the defects; performing single-point repair according to the defect type to obtain a coated component;

[0078] Step S4, placing the glue-coated component in a curing chamber, and adjusting the curing parameters according to the dynamic viscosity characteristic quantity to obtain a packaged product;

[0079] Step S5: cutting and molding the packaged product, and performing an electrical performance test to obtain a packaged power diode.

[0080] Specifically, step S1 includes:

[0081] Step S11, allowing the silica gel to stand at a preset temperature;

[0082] In an embodiment of the present invention, the preset temperature and the resting time are determined by the following formula:

[0083] The preset temperature for static state = Tg + 50°C, in degrees Celsius (°C);

[0084] Wherein, Tg is the glass transition temperature of silica gel, which is determined based on data provided by the silica gel supplier and will not be described in detail here.

[0085] Standing time = basic standing time + standing time compensation coefficient × initial dynamic viscosity, in hours (h);

[0086] Among them, the basic standing time unit is hour (h), and the value range is [1, 2]. Preferably, it is 2; the standing time compensation coefficient unit is (h / cP), and the value range is [0.0002, 0.0005]. Preferably, it is 0.0002; the initial dynamic viscosity unit is centipoise (cP), which is determined according to the value provided by the silicone supplier; those skilled in the art can reasonably adjust the above parameters according to actual conditions, which will not be repeated here.

[0087] It can be understood that when silica gel is left to stand in an environment 50°C above the glass transition temperature, the molecular segments can move freely but no cross-linking is triggered, which can eliminate the viscosity fluctuations caused by internal stress. At the same time, the higher the dynamic viscosity, the worse the colloid fluidity, and the standing time needs to be increased to ensure that large bubbles are naturally discharged for preliminary defoaming.

[0088] Step S12, detecting the dynamic viscosity of the silica gel, and if the dynamic viscosity is not within a preset dynamic viscosity range, adding a diluent or a thickener to adjust the dynamic viscosity;

[0089] If the current dynamic viscosity is greater than the preset upper limit, it indicates that the current fluid protective adhesive is too viscous and a diluent should be added. If the current dynamic viscosity is less than the preset lower limit, it indicates that the current fluid protective adhesive is too thin and a thickener should be added.

[0090] In an embodiment of the present invention, a cone-plate rheometer is used to detect the dynamic viscosity of the fluid protective adhesive;

[0091] Among them, the preset viscosity range is [1800cP, 2200cP], the diluent is preferably methyl vinyl silicone oil, and the thickener is preferably silicon dioxide. The amount of diluent or thickener added is determined according to the data provided by its supplier and will not be repeated here.

[0092] Step S13, repeating step S12, when the detected dynamic viscosity is within the preset dynamic viscosity range, recording the current dynamic viscosity value as the dynamic viscosity characteristic value;

[0093] The present invention precisely controls the dynamic viscosity of the fluid protective adhesive. Since the rheological properties of the colloid directly determine the dispensing accuracy and curing quality, this step transforms the packaging process from "experience-driven" to "data-driven," providing a guarantee for the large-scale manufacturing of high-density, high-reliability power electronic devices.

[0094] Step S14: performing vacuum degassing on the fluid protective adhesive.

[0095] Specifically, in step S14, the vacuum degassing process adopts pulsed negative pressure control, wherein the negative pressure intensity, pulse frequency and degassing time are determined according to the dynamic viscosity characteristic value.

[0096] It is understandable that vacuum degassing is a common process used to remove bubbles from liquids or solids. Its principle is based on the relationship between gas solubility and pressure: in liquids, gases dissolve and form bubbles; when the pressure decreases, the gas solubility decreases, causing the bubbles to be released from the liquid; for liquid degassing, a continuous vacuum degassing method can be used to achieve a more thorough degassing effect by continuously reducing the pressure; while for solid degassing, a short-term high vacuum (i.e. pulsed) degassing method can be used to effectively remove bubbles by quickly reducing the pressure;

[0097] In an embodiment of the present invention,

[0098] Negative pressure intensity = basic negative pressure + dynamic viscosity pressure coefficient × dynamic viscosity characteristic value, unit is MPa;

[0099] It is understandable that the higher the dynamic viscosity, the worse the colloid fluidity, and the negative pressure strength needs to be increased to ensure the migration of bubbles.

[0100] Preferably, the basic negative pressure is 0.05 (MPa), and the dynamic viscosity pressure coefficient is 0.00005 (MPa / cP);

[0101] Pulse frequency = reference frequency - dynamic viscosity frequency coefficient × dynamic viscosity characteristic value, unit is Hz;

[0102] It is understandable that the higher the dynamic viscosity, the worse the colloid fluidity, and the pulse frequency needs to be reduced to avoid bubble retention.

[0103] Preferably, the reference frequency is 0.5 (Hz), and the dynamic viscosity frequency coefficient is 0.0002 (Hz / cP);

[0104] Degassing time = basic time + dynamic viscosity time coefficient × dynamic viscosity characteristic value, unit is min;

[0105] It is understandable that the higher the dynamic viscosity, the slower the bubble migration speed, and the longer the degassing time needs to be.

[0106] Preferably, the base time is 3 (min), and the dynamic viscosity time coefficient is 0.006 (min / cP);

[0107] In the first 50% of the degassing process, a pulsed negative pressure is applied according to the above calculated value to cause the bubbles to expand and burst under the negative pressure, and to be discharged by surface tension under normal pressure. In the second 50% of the degassing process, a constant negative pressure of 50% of the above calculated value of the negative pressure intensity is maintained to continuously aspirate the remaining microbubbles.

[0108] The present invention dynamically adjusts the parameters of the vacuum degassing process based on the dynamic viscosity characteristic of the flowing protective adhesive, matches the characteristics of different batches of colloids, and improves the degassing efficiency; and adopts a two-stage degassing strategy: the pulse stage breaks large bubbles, and the constant pressure stage removes microbubbles, which greatly reduces the bubble residual rate and ensures the qualified rate of subsequent colloid coating and curing.

[0109] For more details, please refer to Figure 2 As shown, the flowchart of step S2 of the packaging method of the power diode of the present invention includes:

[0110] Step S21, adding the fluid protective adhesive into the coating system, fixing a plurality of chip components on a fixture with an adjustable tilt angle to form a chip component array;

[0111] In an embodiment of the present invention, the chip assembly array is a single-row array with a total of 10 chip assemblies, and the interval between every two chip assemblies is 3 mm.

[0112] It is understandable that increasing the number of columns and rows of the chip component array can improve production efficiency, but it is limited by the performance of the coating system and will increase the difference in colloid infiltration time and standing time between each chip component, affecting the consistency of the flexible packaging layer. Those skilled in the art can adjust the number of columns, rows and chip spacing of the chip component array according to actual conditions while ensuring the consistency of the flexible packaging layer, which will not be repeated here.

[0113] Step S22, calculating the single-point glue dispensing amount and glue dispensing speed of the coating system according to the dynamic viscosity characteristic value obtained in step S13;

[0114] In an embodiment of the present invention,

[0115] Single-point glue amount = reference glue amount + (dynamic viscosity coefficient × dynamic viscosity characteristic value / reference dynamic viscosity), unit is μL;

[0116] Preferably, the reference adhesive volume is 0.5 (μL), and the dynamic viscosity coefficient is 0.8 (μL·cP -1 ), the benchmark dynamic viscosity is taken as 1000 (cP).

[0117] It is understandable that the higher the dynamic viscosity, the worse the colloid fluidity, and the amount of single-point glue application needs to be increased to compensate for insufficient spreading; the baseline glue application amount is the minimum glue amount required to cover the upper surface of the chip 3 determined through experiments, and the dynamic viscosity coefficient is calibrated based on leveling tests; the baseline dynamic viscosity is a baseline value of the fluid protective adhesive obtained based on historical data; those skilled in the art can adjust the above coefficients according to actual conditions, which will not be repeated here.

[0118] Glue discharging speed = maximum glue discharging speed × (baseline dynamic viscosity / dynamic viscosity characteristic value), unit is μL / s;

[0119] Preferably, the maximum dispensing speed is 5 (μL / s) and the reference dynamic viscosity is 1000 (cP);

[0120] It is understandable that the higher the dynamic viscosity, the greater the resistance to colloid extrusion, and the glue discharge speed needs to be reduced to ensure the uniformity of the glue layer; the maximum glue discharge speed is the optimal glue discharge speed of the glue dispensing equipment of the coating system in the embodiment of the present invention to avoid droplet breakage; those skilled in the art can adjust the above coefficients according to actual conditions, which will not be repeated here.

[0121] The present invention matches the single-point glue dispensing amount and glue dispensing speed of the coating system with the dynamic viscosity of the fluid curing glue, thereby ensuring the thickness and expansion area of ​​the glue during coating, reducing the thickness fluctuation range of the glue layer and improving the edge coverage, thereby improving the product qualification rate.

[0122] Step S23, locating the position data of each chip component in the chip component array by an image recognition system to obtain the coordinates of the glue outlet of the coating system for each single-point glue application;

[0123] In an embodiment of the present invention, a high-resolution industrial camera is used to capture images of each chip in the chip component array, the position of the upper surface of the upper electrode area 13 is extracted through an edge detection algorithm, and its coordinates relative to the center point of the chip 3 are obtained as the coordinates of the glue outlet of the coating system for each single-point glue application.

[0124] Step S24, moving the glue outlet of the coating system to the starting end of the chip assembly array, and performing a single-point glue application operation on the entire array of chip assemblies so that the fluid protective glue covers the upper surface and circumferential side surfaces of each chip;

[0125] Step S25, adjusting the tilt angle of the fixture to a preset tilt angle so that the gap formed between the upper frame and the lower frame of the chip assembly forms an angle with the horizontal plane, so that the fluid protective glue can infiltrate the gap under the action of gravity;

[0126] Specifically, in step S25, the preset inclination angle and the infiltration time are calculated according to the dynamic viscosity characteristic value, and the preset inclination angle and the infiltration time are positively correlated with the dynamic viscosity characteristic value.

[0127] In an embodiment of the present invention,

[0128] Preset inclination angle = maximum allowable angle × {1-e^[attenuation coefficient × (dynamic viscosity characteristic value - 1800)]}, unit is °.

[0129] Wherein, 1800 is the minimum value of the preset viscosity range, in cP.

[0130] Preferably, the maximum allowable angle is 8°, and the attenuation coefficient is -0.00439 (cP -1 ).

[0131] It can be understood that the higher the dynamic viscosity, the worse the colloid fluidity, and the inclination angle needs to be increased to enhance the gravity-driven effect. The maximum allowable angle is used to prevent the preset inclination angle from being too large and causing glue overflow. The attenuation coefficient is obtained based on the rheological properties of fluid protective glue with different dynamic viscosities. Those skilled in the art can adjust the above coefficient according to actual conditions, which will not be repeated here.

[0132] Immersion time = reference time × (dynamic viscosity characteristic value / reference dynamic viscosity), unit is s;

[0133] Preferably, the reference time is 5 (s), and the soaking time is ≤ 15 (s).

[0134] It is understandable that the higher the dynamic viscosity, the slower the colloid flow rate, and the infiltration time needs to be extended to ensure complete filling. At the same time, a maximum infiltration time is specified to prevent delays in the production line cycle. The reference time is the flow time of the fluid protective glue obtained based on historical data. Those skilled in the art can adjust the above coefficients according to actual conditions, which will not be repeated here.

[0135] In the present invention, by matching the inclination angle and immersion time of the fixture with the dynamic viscosity of the fluid protective glue, the low dynamic viscosity colloid with strong fluidity uses a smaller inclination angle and a shorter immersion time, thereby avoiding excessive flow under the action of gravity and causing glue overflow; the high dynamic viscosity colloid with poor fluidity uses a larger inclination angle and a longer immersion time, thereby enhancing the gravity-driven effect to completely fill the gap, thereby reducing the defect rate and simultaneously solving the problems of low dynamic viscosity glue overflow and high dynamic viscosity insufficient filling; reducing manual intervention and adapting to the needs of automated production lines.

[0136] Step S26, restoring the angle of the fixture to the horizontal plane, moving the scraper of the coating system to the starting end of the chip assembly, and adjusting the height of the scraper according to the amount of glue applied at a single point;

[0137] Specifically, in step S26, after the angle of the clamp is restored to the horizontal plane, the clamp is vibrated for a preset vibration duration to eliminate the surface tension of the colloid, and the vibration duration is determined according to the dynamic viscosity characteristic value.

[0138] In an embodiment of the present invention,

[0139] Vibration duration = basic vibration duration × (dynamic viscosity characteristic value / reference dynamic viscosity), the unit is seconds (s);

[0140] Preferably, the basic vibration duration is 3 (s); the vibration frequency can be set to 50-80 Hz, and the vibration amplitude can be set to 20-30 μm; those skilled in the art can reasonably adjust the above parameters according to actual conditions, which will not be repeated here.

[0141] It is understandable that the vibration direction of the clamp is perpendicular to the scraping direction to avoid the deviation of the glue.

[0142] The present invention matches the vibration duration of colloids with different viscosities, eliminates the surface tension difference of colloids with different dynamic viscosities through vibration, reduces the shrinkage phenomenon at the edge, improves the coverage rate of the edge, and at the same time improves the thickness uniformity of the colloid, thereby improving the accuracy of the subsequent scraper in thinning and leveling.

[0143] Step S27, moving the scraper in the forward direction along the current column to thin the adhesive layer;

[0144] Step S28 , moving the scraper in the opposite direction along the same column to level the adhesive layer to form a flexible packaging layer.

[0145] Specifically, in step S28, when the scraper is moved in the reverse direction, the moving speed of the scraper is reduced to a preset ratio of the moving speed of the scraper when the scraper is moved in the forward direction, and the scraper angle is adjusted to axially deflect around the axis formed by the upper edge of the scraper so that the height of the scraper is lowered to a preset height, so as to apply shear force to level the adhesive layer.

[0146] In an embodiment of the present invention, the speed of the forward moving scraper is 20 mm / s. The height of the scraper is defined as the distance between the lowest point of the scraper where the scraper is applied and the upper surface of the upper electrode region 42. After the forward moving scraper thins the adhesive layer and the reverse moving scraper flattens the adhesive layer, the thickness of the flexible encapsulation layer 4 after curing is [10, 30] μm. The scraper height when the scraper is moved forward is calculated according to the following formula:

[0147] Scraper height = basic scraper height + rebound coefficient × (base dynamic viscosity / dynamic viscosity characteristic value), unit is μm;

[0148] Preferably, the rebound coefficient is 5 (μ / cP); the base scraper height is 10 (μm);

[0149] When the scraper moves in the reverse direction, its moving speed is reduced to 50% of that in the forward direction (i.e., 10 mm / s), and the scraper angle is deflected axially so that the height of the scraper drops to a preset height. It will be understood by those skilled in the art that the deflection angle is determined by the size of the scraper and is negatively correlated with it, wherein:

[0150] Preset descent height = basic descent height + rebound coefficient × (reference dynamic viscosity / dynamic viscosity characteristic value), unit is μm;

[0151] Preferably, the base drop height is 3 (μm).

[0152] It is understandable that after the scraper performs the scraping operation, the colloid will rebound, and the amplitude of the rebound is negatively correlated with the dynamic viscosity characteristic of the colloid;

[0153] The present invention adopts a two-step thinning-leveling method, wherein the forward scraping thinning method preliminarily controls the thickness of the glue layer through high-speed scraping, providing a margin for subsequent leveling; the reverse scraping leveling method eliminates accumulation through low-speed scraping combined with shear force, compresses the thickness fluctuation range, breaks through the physical limitations of single scraping, and realizes ultra-thin flexible packaging; at the same time, the scraper height is dynamically adjusted according to the dynamic viscosity of the colloid, compensates for the elastic recovery of the colloid, solves the quality fluctuation caused by the rebound effect, and further enhances the process stability.

[0154] For more details, please refer to Figure 3 As shown, it is a flow chart of step S3 of the packaging method of the power diode of the present invention, and the step S3 includes:

[0155] Step S31, obtaining reflectivity change data of the flexible packaging layer of each chip component in the chip component array through detection by an image recognition system;

[0156] In an embodiment of the present invention, an LED light source and a high-resolution industrial camera are used to detect the reflectivity change of the chip component.

[0157] Preferably, an LED light source with a wavelength of 650 nm is used, and the incident angle of the light source is fixed at 60° to suppress the interference of mirror reflection and enhance the contrast of the edge of the adhesive layer.

[0158] Use an industrial camera to photograph the chip surface and generate a reflectivity distribution map. For a single chip component, the rectangle formed by the upper surface edge of the chip 3 offset 1mm outward is used as the reflectivity judgment area.

[0159] The following feature data is extracted from the reflectivity judgment area:

[0160] A g : The area ratio of high reflectivity pixels, where high reflectivity is defined as a reflectivity ≥ 80%;

[0161] A d : The area ratio of low reflectivity pixels, where low reflectivity is defined as reflectivity ≤ 25%;

[0162] G: reflectivity gradient change rate, which is defined as the average value of the reflectivity difference between adjacent pixels per millimeter, unit is (% / mm);

[0163] S: shape factor of low reflectivity pixel area, specifically , where A is the area of ​​the low reflectivity pixel region, in square micrometers (μm 2 ), P is the perimeter of the low reflectivity pixel area in micrometers (μm).

[0164] It is understandable that It is used to measure the degree to which the shape of the low-reflectivity pixel area is close to a circle. When S=1, the low-reflectivity pixel area is a perfect circle. The more complex the shape, the smaller the S value. Bubbles are usually approximately circular due to surface tension, and their S value is larger. Uneven thickness is manifested as an area with uneven diffusion of the adhesive layer, and its shape is more irregular (such as sheet or strip), and its S value is smaller.

[0165] Based on the reflectivity gradient change rate G, the determination coefficient R² is calculated, which is used in statistics to quantify the degree of fit of the linear regression model to the data. The value range is [0,1]. The closer it is to 1, the more the change in the reflectivity gradient conforms to the linear trend.

[0166] Step S32, performing a first-level screening of the flexible encapsulation layer based on the area ratio of high-reflectivity pixels to low-reflectivity pixels and the reflectivity gradient change rate in the reflectivity change data to determine whether the flexible encapsulation layer is qualified, and performing preliminary defect classification on unqualified flexible encapsulation layers;

[0167] In an embodiment of the present invention, performing the first level screening includes:

[0168] If A g >3%, it indicates that there is suspicion of missing coating, and the second level of missing coating confirmation is entered; if A d >8% and G>5% / mm, it indicates that there is suspicion of uneven thickness, and the second level of uneven thickness determination is entered; if A d >8% and G <2% / mm, it indicates that there is suspicion of bubbles and enters the second-level judgment of bubble confirmation; other situations indicate that the judgment result of the reflectivity judgment area is qualified.

[0169] Step S33: performing a second-level determination based on the area ratio of high-reflectivity pixels to low-reflectivity pixels in the reflectivity change data, the reflectivity gradient change rate, and the shape factor of the low-reflectivity pixel area to obtain a specific defect type of the unqualified flexible encapsulation layer;

[0170] In an embodiment of the present invention, performing the second level determination includes:

[0171] When confirming the missing coating: When A is satisfied at the same time g >5% and G>10% / mm, it is determined as a coating defect; when only A g When the error is greater than 5%, it is marked as suspected coating leakage and needs to be repeated;

[0172] When the thickness unevenness is confirmed: When A is satisfied at the same time d >10%, S<0.3 and R 2 >0.8, it is judged as uneven thickness defect; when only A d When the value is greater than 10% and S is less than 0.3, it is marked as suspected uneven thickness and needs to be repeated.

[0173] When performing the bubble confirmation: when A is satisfied at the same time d >10%, S≥0.3 and R 2 <0.3 (the reflectivity gradient fluctuates irregularly), it is determined to be a bubble defect. d When the value is greater than 10% and S is greater than or equal to 0.3, it is marked as a suspected bubble defect and needs to be repeated.

[0174] It is understandable that in this second level of determination:

[0175] When both A and g When A>5% and G>10% / mm, g G>5% indicates that there is an exposed portion of the upper electrode area 42. G>10% / mm indicates that the reflectivity gradient change rate is large, that is, there is an uncoated portion between the upper electrode area 42 and the chip 1, and there is a significant reflectivity change, so it is judged as a coating defect;

[0176] When both A and d >10%, S<0.3 and R 2 >0.8, A d >10% indicates that the upper electrode region 42 has a large area of ​​excessive thickness, S<0.3 indicates that the shape of the low reflectivity pixel area is relatively irregular, R 2 >0.8 indicates that the reflectivity gradient changes linearly, so it is judged as a thickness uneven defect;

[0177] When both A and d >10%, S≥0.3 and R 2 <0.3, A d >10% indicates that the upper electrode region 42 has a large area of ​​excessive thickness, S≥0.3 indicates that the shape of the low reflectivity pixel area is relatively regular, R 2 >0.8 indicates that the reflectivity gradient fluctuates irregularly, so it is judged to be a bubble defect.

[0178] Step S34, classifying and marking the position of the chip component where the flexible encapsulation layer is located according to the defect type, and adjusting the single-point adhesive dispensing parameters or correcting the thinning and leveling operation parameters based on the defect location distribution and defect type;

[0179] In an embodiment of the present invention,

[0180] When there is a missing coating defect, the subsequent single-point glue amount is adjusted as follows:

[0181] New fabric glue amount = original fabric glue amount × (1 + missed coating area compensation coefficient × A g ), the unit is microliter (μL);

[0182] Preferably, the missing coating area compensation coefficient is 0.3.

[0183] When there is a thickness unevenness defect, the position distribution of the thickness unevenness defect is further determined, wherein:

[0184] For a single row of the chip assembly array, if three consecutive flexible encapsulation layers or more than 50% of the flexible encapsulation layers have uneven thickness defects, the scraper height when moving the scraper in the reverse direction shall be corrected as follows:

[0185] New scraper height = original scraper height × [1-thickness deviation correction factor × (G-10%)], unit is micron (μm);

[0186] Preferably, the thickness deviation correction coefficient is 0.2.

[0187] It is understandable that when uneven thickness defects occur in a continuous flexible packaging layer, it indicates that the height of the scraper is too high and can only level part of the thickness of the flexible packaging layer. Therefore, the scraper height needs to be lowered when moving the scraper in the reverse direction.

[0188] For a single row of the chip assembly array, if the requirement of uneven thickness of three consecutive flexible encapsulation layers or more than 50% of the flexible encapsulation layers is not met, the scraper speed when moving the scraper in the forward direction shall be corrected as follows:

[0189] New speed = original speed × [1-speed correction factor × (G-10%)], unit is micron (μm);

[0190] Preferably, the speed correction coefficient is 1.

[0191] It is understandable that when there is a discontinuous uneven thickness defect in the flexible packaging layer, it indicates that the scraper is moving too fast, resulting in fluctuations in the thickness of the flexible packaging layer during the thinning and leveling process. Therefore, the scraper speed when moving the scraper in the forward direction (which is also related to the scraper speed when moving the scraper in the reverse direction) needs to be lowered.

[0192] When bubble defects exist, the subsequent vibration amplitude is adjusted as follows:

[0193] The vibration amplitude is enhanced, where

[0194] New vibration amplitude = original vibration amplitude × (1 + bubble size influence coefficient × A), unit is micron (μm);

[0195] Preferably, the bubble size influence coefficient is 0.1 (μm -2 ).

[0196] The vibration time is extended, wherein,

[0197] New vibration duration = original vibration duration × (1 + shape factor correction coefficient × S), in seconds (s);

[0198] Preferably, the shape factor correction coefficient is 0.2.

[0199] It can be understood that the bubble residual rate can be reduced through vibration optimization, wherein the larger the bubble size, the larger the required vibration amplitude; the smaller the shape factor, the more irregular the bubble, and the longer the required vibration time.

[0200] Step S35, performing corresponding repair operations on the flexible packaging layers of all the chip components with marked coordinates in sequence according to the classification marks;

[0201] In an embodiment of the present invention, for the flexible packaging layer determined to have a coating missing defect, a single-point glue spreading operation, a single-point forward thinning and a reverse leveling operation are sequentially performed to fill the coating missing area and level the area; for the flexible packaging layer determined to have an uneven thickness defect, a single-point forward thinning and a reverse leveling operation are sequentially performed to level the excessively high portion of the uneven thickness area; for the flexible packaging layer determined to have a bubble defect, a pulsed negative pressure (-0.05 MPa, cycle 1 s) is first applied to the bubble area to suck and break the bubble, and then a single-point glue spreading operation, a single-point forward thinning and a reverse leveling operation are sequentially performed.

[0202] Step S36, repeating steps S31 to S35 until all areas of the chip component array pass the integrity test to obtain a glue-coated component.

[0203] The present invention takes into account both efficiency and accuracy through a three-level mechanism of coarse screening, fine judgment, and adjustment; it combines multi-dimensional features such as area ratio, edge sharpness, and shape factor to distinguish easily confused defects, accurately repair corresponding gluing defects, and prevent ineffective repairs or overall rework; at the same time, the defects are fed back to the process for correction, thereby improving automation and preventing continuous defective batches.

[0204] Specifically, step S4 includes:

[0205] Step S41, calculating parameters of the curing process according to the dynamic viscosity characteristic value obtained in step S13;

[0206] Specifically, the parameters of the curing process include: pre-curing temperature, main curing time and heating rate; since it has been determined that all areas of the chip component array have passed the integrity test, the thickness of the sealing layer is considered to be consistent. Therefore, the pre-curing temperature and the main curing time are positively correlated with the dynamic viscosity characteristic quantity, and the heating rate is negatively correlated with the dynamic viscosity characteristic quantity.

[0207] In an embodiment of the present invention, the pre-curing temperature, the main curing time and the heating rate are determined by the following formula:

[0208] Pre-curing temperature = basic pre-curing temperature + pre-curing temperature coefficient × dynamic viscosity characteristic value, the unit is degrees Celsius (℃);

[0209] Preferably, the basic pre-curing temperature is 40 (℃), and the pre-curing temperature coefficient is 0.02 (cP -1 );

[0210] It is understandable that the cross-linking reaction of silicone rubber needs to overcome the entanglement energy of molecular chains. The higher the viscosity, the greater the resistance to molecular movement, and a higher pre-curing temperature is required to stimulate the initial cross-linking to form a stable support structure. The purpose of expelling microbubbles during the low-temperature pre-curing stage is to prevent the violent reaction inside the colloid caused by direct high-temperature curing, which will release heat too quickly and prevent the gas from escaping in time. At the same time, the higher the viscosity, the more difficult it is to expel the residual microbubbles in the colloid, and a higher pre-curing temperature is required to allow the microbubbles to overcome the resistance of the colloid and be discharged autonomously.

[0211] Main curing time = basic main curing time × [(dynamic viscosity characteristic value / base dynamic viscosity) ^ 1.2] × (main curing peak temperature - pre-curing temperature) / main curing peak temperature, in hours (h);

[0212] Preferably, the basic main curing time is 0.6 (h).

[0213] The unit of the main curing peak temperature is degrees Celsius (°C), which is determined based on the value provided by the silicone supplier and will not be repeated here.

[0214] It is understandable that the cross-linking reaction of high-viscosity silicone has non-Newtonian fluid characteristics, the reaction rate decays exponentially with viscosity, and it takes a longer time to cure. At the same time, the greater the difference between the pre-curing temperature and the main curing peak temperature, the more significant the thermal stress gradient inside the silicone, and the longer the insulation time needs to be to balance the reaction process.

[0215] Heating rate = basic heating rate − heating rate coefficient × dynamic viscosity characteristic quantity, in degrees Celsius per minute (℃ / min);

[0216] Preferably, the basic heating rate is 2 (°C / min); the heating rate coefficient is 0.0005 (°C / (min·cP)).

[0217] It is understandable that high-viscosity silicone has poor thermal conductivity. Heating the temperature too quickly will cause the surface to solidify without reacting internally, resulting in internal stress cracks. Therefore, for higher-viscosity silicone, the heating rate needs to be reduced to balance curing efficiency and quality.

[0218] The present invention uses low-temperature pre-curing to eliminate microbubbles that cannot be identified in step S3 due to the resolution limit of the industrial camera, while forming a stable support structure. By increasing the temperature gradient during the main curing and matching the dynamic viscosity characteristic of the silicone, the uniformity of the cross-linking degree is improved, the curing quality is enhanced, and the thermal cycle life of the product is extended.

[0219] Step S42, placing the glue-coated component in a curing chamber and filling it with nitrogen to eliminate interference from oxygen;

[0220] In an embodiment of the present invention, the glue-coated assembly is placed in a closed high-temperature curing chamber, the vacuum pump is started to evacuate to -80 kPa and high-purity nitrogen (purity ≥ 99.999%) is filled to normal pressure at a flow rate of 10 L / min, and the oxygen concentration is maintained at <50 ppm.

[0221] It can be understood that the process of filling with nitrogen is a relatively common practice for the curing reaction. By using nitrogen, the upper frame 2, the lower frame 3 and the connecting frame 4 are protected to avoid oxidation. Those skilled in the art can make reasonable adjustments to the process according to actual conditions, which will not be repeated here.

[0222] Step S43, pre-curing the flexible encapsulation layer at a low temperature to eliminate bubbles in the colloid and form a stable support structure;

[0223] In an embodiment of the present invention, the pre-curing temperature is maintained constant for 40 to 60 minutes.

[0224] Step S44, gradually increasing the curing temperature to perform primary curing on the silica gel;

[0225] In an embodiment of the present invention, the temperature is increased to the main curing peak temperature at the heating rate, and constant temperature curing is performed for the main curing time.

[0226] Step S45, checking the thickness data of the cured flexible packaging layer through an image recognition system;

[0227] In an embodiment of the present invention, an industrial camera is used to photograph the side surface of the chip component to obtain thickness data of the flexible packaging layer thereon.

[0228] Step S46, comparing the thickness data with the target thickness to determine whether the thickness of the flexible encapsulation layer after curing is qualified;

[0229] In an embodiment of the present invention, the target thickness of the flexible encapsulation layer is [10, 30] μm. When the thickness data of the flexible encapsulation layer is not within the target thickness range, it is determined that the thickness of the flexible encapsulation layer is unqualified.

[0230] Step S47, degumming the unqualified flexible encapsulation layer after curing, and re-gluing and curing the flexible encapsulation layer, while adjusting the parameters of the curing process to reduce the shrinkage rate of the silicone to improve the dimensional stability of the flexible encapsulation layer;

[0231] In an embodiment of the present invention, the debonding operation is to use infrared focusing with a spot diameter of 4 mm to locally heat to 300°C to carbonize the silica gel and remove residues; the gluing operation is performed according to the above steps S2 to S3, and the curing operation is performed according to the above step S4, while adjusting the parameters of the curing process, specifically:

[0232] New main curing time = main curing time × {[1 / (dynamic viscosity characteristic value / 1000)^0.5]+0.2}, in hours (h);

[0233] It is understandable that the cross-linking density will directly affect the shrinkage rate of the product. The greater the dynamic viscosity of the silicone, the greater the cross-linking density, and the greater the shrinkage rate of the product. At the same time, too long a curing time will cause excessive cross-linking of the silicone, thereby increasing the shrinkage rate. Therefore, reducing the curing time (the greater the dynamic viscosity characteristic value of the silicone, the greater the reduction) can reduce the shrinkage rate of the silicone and improve the dimensional stability of the flexible packaging layer.

[0234] Step S48, repeating steps S45 to S47 until all the cured flexible packaging layers reach the target thickness, thereby obtaining a packaging product;

[0235] Step S5: cutting and molding the packaged product, and performing an electrical performance test to obtain a packaged power diode.

[0236] It is understandable that this process may also include continuously storing and learning adjustment data of process parameters during several packaging processes, so as to obtain the optimal parameters of the packaging process based on the process parameters through big data analysis or model analysis.

[0237] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A packaging process for a power diode, characterized in that: include: Step S1, pre-treating the silica gel into a fluid state and adjusting the dynamic viscosity value to within a preset range to obtain a fluid protective gel, and recording the current dynamic viscosity value of the fluid protective gel as a dynamic viscosity characteristic value; Step S2: adding the fluid protective adhesive to a coating system, adjusting the single-point adhesive application parameters of the coating system according to the dynamic viscosity characteristic value, and performing a single-point adhesive application operation. Using a scraper, the fluid protective adhesive is thinned once by moving the scraper forward and then leveled once by moving the scraper backward to form a flexible encapsulation layer on the surface of the chip component array. Step S3, detecting a change in the reflectivity of the flexible encapsulation layer through an image recognition system to determine whether the flexible encapsulation layer has defects and the specific type of defects, and adjusting the operating parameters of the coating system based on the location distribution and type of the defects; performing single-point repair according to the defect type to obtain a coated component; Step S4, placing the glue coating component in a curing chamber, and adjusting the curing parameters of the curing chamber according to the dynamic viscosity characteristic quantity to cure the flexible packaging layer to obtain a packaging product; Step S5: cutting and molding the packaged product, and performing an electrical performance test to obtain a packaged power diode.

2. The packaging process of the power diode according to claim 1, characterized in that: The step S1 comprises: Step S11, allowing the silica gel to stand at a preset temperature; Step S12, detecting the dynamic viscosity of the silica gel, and if the dynamic viscosity is not within a preset dynamic viscosity range, adding a diluent or a thickener to adjust the dynamic viscosity; Step S13, repeating step S12, when the detected dynamic viscosity is within the preset dynamic viscosity range, recording the current dynamic viscosity value as the dynamic viscosity characteristic value; Step S14: vacuum degassing the silica gel to obtain a fluid protective adhesive.

3. The packaging process of the power diode according to claim 2, characterized in that: In step S14, the vacuum degassing process is controlled by pulsed negative pressure, wherein the negative pressure intensity, pulse frequency and degassing time are determined according to the dynamic viscosity characteristic value.

4. The packaging process for a power diode according to claim 3, characterized in that: The step S2 comprises: Step S21, adding the fluid protective adhesive into the coating system, fixing a plurality of chip components on a fixture with an adjustable tilt angle to form a chip component array; Step S22, calculating the single-point glue dispensing amount and glue dispensing speed of the coating system according to the dynamic viscosity characteristic value obtained in step S13; Step S23, locating the position data of each chip component in the chip component array by an image recognition system to obtain the coordinates of the glue outlet of the coating system for each single-point glue application; Step S24, moving the glue outlet of the coating system to the starting end of the chip assembly array, and performing a single-point glue application operation on the entire array of chip assemblies so that the fluid protective glue covers the upper surface and circumferential side surfaces of each chip; Step S25, adjusting the tilt angle of the fixture to a preset tilt angle so that the gap formed between the upper frame and the lower frame of the chip assembly forms an angle with the horizontal plane, so that the fluid protective glue can infiltrate the gap under the action of gravity; Step S26, restoring the angle of the fixture to the horizontal plane, moving the scraper of the coating system to the starting end of the chip assembly, and adjusting the height of the scraper according to the amount of glue applied at a single point; Step S27, moving the scraper in the forward direction along the current column to thin the adhesive layer; Step S28 , moving the scraper in the opposite direction along the same column to level the adhesive layer to form a flexible packaging layer.

5. The packaging process of the power diode according to claim 4, characterized in that: In step S25 , the preset inclination angle and the infiltration time are calculated based on the dynamic viscosity characteristic value, and the preset inclination angle and the infiltration time are positively correlated with the dynamic viscosity characteristic value.

6. The packaging process for a power diode according to claim 4, characterized in that: In the step S26, after the angle of the clamp is restored to the horizontal plane, the clamp is vibrated for a preset vibration duration to eliminate the surface tension of the colloid. The vibration duration is determined according to the dynamic viscosity characteristic value.

7. The packaging process for a power diode according to claim 4, characterized in that: In step S28, when the scraper is moved in the reverse direction, the moving speed of the scraper is reduced to a preset ratio of the moving speed of the scraper when the scraper is moved in the forward direction, and the scraper angle is adjusted to deflect axially along the upper edge of the scraper so that the height of the scraper is lowered to a preset height, so as to apply shear force to level the adhesive layer.

8. The packaging process for a power diode according to claim 6, characterized in that: The step S3 comprises: Step S31, obtaining reflectivity change data of the flexible packaging layer of each chip component in the chip component array through detection by an image recognition system; Step S32, performing a first-level screening of the flexible encapsulation layer based on the area ratio of high-reflectivity pixels to low-reflectivity pixels and the reflectivity gradient change rate in the reflectivity change data to determine whether the flexible encapsulation layer is qualified, and performing preliminary defect classification on unqualified flexible encapsulation layers; Step S33: performing a second-level determination based on the area ratio of high-reflectivity pixels to low-reflectivity pixels in the reflectivity change data, the reflectivity gradient change rate, and the shape factor of the low-reflectivity pixel area to obtain a specific defect type of the unqualified flexible encapsulation layer; Step S34, classifying and marking the position of the chip component where the flexible encapsulation layer is located according to the defect type, and adjusting the single-point adhesive dispensing parameters or correcting the thinning and leveling operation parameters based on the defect location distribution and defect type; Step S35, performing corresponding repair operations on the flexible packaging layers of all the chip components with marked coordinates in sequence according to the classification marks; Step S36, repeating steps S31 to S35 until all areas of the chip component array pass the integrity test to obtain a glue-coated component.

9. The packaging process for a power diode according to claim 8, characterized in that: The step S4 comprises: Step S41, calculating parameters of the curing process according to the dynamic viscosity characteristic value obtained in step S13; Step S42, placing the glue-coated component in a curing chamber and filling it with nitrogen to eliminate interference from oxygen; Step S43, pre-curing the flexible packaging layer at a low temperature to eliminate bubbles in the glue and form a stable support structure; Step S44, gradually increasing the curing temperature to perform primary curing on the silica gel; Step S45, checking the thickness data of the cured flexible packaging layer through an image recognition system; Step S46, comparing the thickness data with the target thickness to determine whether the thickness of the flexible encapsulation layer after curing is qualified; Step S47, degumming the unqualified flexible encapsulation layer after curing, and re-gluing and curing the flexible encapsulation layer, while adjusting the parameters of the curing process to reduce the shrinkage rate of the silicone to improve the dimensional stability of the flexible encapsulation layer; Step S48, repeating steps S45 to S47 until all the cured flexible packaging layers reach the target thickness, thereby obtaining a packaging product.

10. The packaging process of a power diode according to claim 9, characterized in that: The parameters of the curing process include: pre-curing temperature, main curing time and heating rate; the pre-curing temperature is positively correlated with the dynamic viscosity characteristic value, and the main curing time and heating rate are negatively correlated with the dynamic viscosity characteristic value.

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