LED nixie multi-stage gradient baking curing process

Abstract

The application discloses a kind of LED nixie tube multi-section type gradient baking curing process, belong to LED nixie tube packaging technical field, including low-temperature bubble removal, medium-temperature gel, high-temperature curing three core stages, by controlling uniform gradient temperature rise and stage heat preservation, cooperate normal pressure / micro negative pressure environment, realize filling sealant complete defoaming, gradually solidification.The application effectively solves the problems of bubble residue, high internal stress, colloid cracking and delamination in traditional process, greatly improves the product transmittance, cold and hot impact reliability and production yield, adapts to mainstream LED nixie tube filling sealant, compatible with existing production equipment, simple process, strong versatility, suitable for LED nixie tube large-scale packaging production.

Description

Technical Field

[0001] This invention relates to the field of LED digital tube packaging and manufacturing technology, specifically to a multi-stage gradient baking and curing process system for LED digital tubes. Background Technology

[0002] LED digital tubes, as basic display devices, are widely used in home appliances, industrial control, instruments and other fields. Their packaging quality directly determines the product's lifespan and operational stability.

[0003] Currently, most LED digital tubes in the industry use epoxy resin, addition-type silicone, and other potting compounds for encapsulation and protection. Traditional encapsulation and curing processes generally employ single-stage high-temperature curing or simple two-stage curing, which has many technical defects in actual production. Firstly, if the single-stage high-temperature heating rate is too fast, the residual stirring inside the potting compound and the tiny air bubbles entrained during the potting process will expand rapidly at high temperatures and cannot effectively escape. They will be locked inside the compound, forming defects such as pinholes, pits, and air bubbles. This not only reduces the light transmittance and display clarity of the digital tube, but also leads to a significant decrease in the insulation performance and mechanical strength of the compound. Secondly, the traditional process has an excessively large temperature gradient, resulting in rapid cross-linking and curing of the colloid surface layer while the internal colloid cures later. This asynchronous curing of the internal and external layers generates huge internal stresses, which can easily lead to problems such as colloid cracking, delamination and detachment of the colloid from the support / PCB substrate during long-term use or under alternating high and low temperatures. Consequently, the product has poor reliability in thermal shock and can only withstand a limited number of thermal shock cycles.

[0004] Third, problems such as insufficient curing and residual bubbles directly lead to low product yield, with defect rates generally ranging from 2% to 15%. Rework costs and raw material losses remain high. At the same time, the products lack resistance to aging and temperature changes, and their service life is difficult to meet the needs of high-end application scenarios.

[0005] Therefore, the existing LED digital tube baking and curing process needs further improvement. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-stage baking and curing process for LED digital tubes. This process includes low-temperature debubbling, medium-temperature gelation, and high-temperature curing. By precisely controlling the temperature gradient, uniformly raising and lowering the temperature, and curing in stages, it completely solves the technical problems of residual bubbles, excessive internal stress, and uneven curing, thereby improving the packaging quality and product reliability of LED digital tubes.

[0007] To achieve the above objectives, the present invention adopts the following solution: a multi-segment gradient baking and curing process for LED digital tubes, characterized by comprising the following steps: S1. Place the LED digital tube semi-finished product after potting with the encapsulant into an oven and heat it to 45-65℃ at a rate of ≤3℃ / min. If possible, keep it at room temperature or under a slight negative pressure of -0.02 to -0.05MPa for 1-3 hours. If not possible, this negative pressure environment can be omitted, and low-temperature degassing can be performed. During this stage, the colloid maintains a low viscosity and flow state. Under the action of the mild temperature, the internal micro bubbles slowly rise and completely break and are discharged, avoiding the rapid cross-linking of the colloid at high temperature that would cause the bubbles to lock up, thus achieving complete degassing.

[0008] S2. After the low-temperature degassing is completed, the oven temperature is raised from the low-temperature degassing temperature to 70-85℃ at a uniform heating rate of ≤2℃ / min, and kept at this temperature for 2-4 hours to carry out medium-temperature gelation. During this stage, the potting compound undergoes a preliminary cross-linking reaction to form a semi-solid gel, which fixes the colloidal structure after degassing, prevents secondary air intake, and completes deep degassing inside the colloidal compound, giving the colloidal compound basic support strength and preventing deformation and flow during subsequent high-temperature heating.

[0009] S3. After the medium-temperature gelation is completed, the oven temperature is raised from the medium-temperature gelation temperature to 90-110℃ at a uniform heating rate of ≤2℃ / min, and held for 2-4 hours for high-temperature curing. During this stage, the colloid undergoes a complete cross-linking and curing reaction, achieving the designed hardness, glass transition temperature, mechanical strength and insulation properties, realizing complete stability of the colloid structure and meeting the encapsulation performance requirements.

[0010] S4. After high-temperature curing, reduce the oven temperature to room temperature at a uniform cooling rate of ≤3℃ / min, and then remove the product.

[0011] This further releases residual stress within the colloid, improving the product's bonding reliability.

[0012] As another improvement to the multi-segment gradient baking and curing process of the LED digital tube of the present invention, the heating process in step S1 is as follows: the temperature is raised from room temperature to 45-55℃, and kept at that temperature for 30 minutes to 1 hour, and then the temperature is raised to 55-65℃ and kept at that temperature for 30 minutes to 1 hour.

[0013] As another improvement to the multi-segment gradient baking and curing process of the LED digital tube of the present invention, the heating process in step S2 is as follows: 70-80℃, hold for 1 to 2 hours; 80-90℃, hold for 1-2 hours.

[0014] As another improvement to the multi-stage gradient baking and curing process of the LED digital tube of the present invention, after the glue is poured in step S1, the LED digital tube semi-finished product is first left to stand for 10-30 minutes before entering the baking and curing process.

[0015] As another improvement to the multi-segment gradient baking and curing process of the LED digital tube of the present invention, the potting compound in step S1 is one of epoxy resin potting compound, addition-type silicone potting compound, or epoxy-silicone composite potting compound.

[0016] As another improvement to the multi-segment gradient baking and curing process of the LED digital tube of the present invention, the potting compound needs to be degassed under vacuum at -0.08 to -0.09 MPa for 15-30 minutes before use to remove the air bubbles generated during the stirring process.

[0017] As another improvement to the multi-segment gradient baking and curing process of the LED digital tube of the present invention, the temperature in the low-temperature degassing stage of step S1 is 50-60℃, and the temperature is maintained for 3-4 hours.

[0018] As another improvement to the multi-segment gradient baking and curing process of the LED digital tube of the present invention, the temperature of the warm gelation stage in step S2 is 85-95℃, and the temperature is maintained for 1.5-2h.

[0019] As another improvement to the multi-segment gradient baking and curing process of the LED digital tube of the present invention, the high temperature curing stage in step S3 is 130-140℃ and the holding time is 2.5-3h.

[0020] In summary, the advantages of this invention compared to the prior art are as follows: First, this invention achieves complete removal of colloidal bubbles through a three-stage process of low-temperature gentle degassing, negative pressure assisted degassing, medium-temperature gelation, and high-temperature curing. The finished product is free of pinholes, pits, and air bubble defects, and the light transmittance is increased by 3%-5%, significantly improving display clarity. Each of the three stages—S1 low-temperature degassing, S2 medium-temperature gelation, and S3 high-temperature curing—can be further divided into two or more sub-stages. Second, this invention features uniform gradient heating and cooling throughout the entire process, allowing the colloid to solidify gradually, improving the synchronization of internal and external curing, and significantly reducing residual internal stress. In high and low temperature cycling tests from -40℃ to 105℃, the product achieves a ≥99% pass rate for 600 cycles, eliminating problems such as colloid cracking, delamination, and detachment.

[0021] Third, after complete curing, the crosslinking density and glass transition temperature of the colloid of this invention are increased by 5-10℃, and the aging resistance, temperature change resistance and insulation performance are significantly enhanced, extending the product service life by more than 30%, making it suitable for high-end and harsh environment application scenarios. IV. Through the process of this invention, the packaging defect rate such as bubbles, cracks, and delamination is reduced from 2%-15% to below 0.5%, which greatly reduces rework and raw material loss, lowers production costs, and improves the efficiency of large-scale production. Fifth, the process of this invention is compatible with mainstream LED digital tube potting compounds in the industry, and is compatible with existing programmable temperature-controlled oven equipment. No additional large-scale equipment investment is required. The process parameters are adjustable and can be adapted to the packaging and production of digital tubes of different specifications.

[0022] VI. This invention uses epoxy resin with a Tg of not less than 125, and the high temperature curing temperature is increased by 10-15℃ compared to existing methods. In the high and low temperature cycle test from -40℃ to 125℃, the product has a 500-cycle pass rate of ≥99%, eliminating problems such as colloid cracking, delamination, and peeling, and is suitable for automotive-grade products. Detailed Implementation

[0023] The above and other technical features and advantages of the present invention will be described in more detail below.

[0024] Example 1 This invention discloses a multi-segment gradient baking and curing process for LED digital tubes, comprising the following steps: S1. Raw material preparation: Prepare semi-finished LED digital tubes that have completed die bonding and wire bonding, and E51 type epoxy resin potting compound; S2. Pre-treatment: Place E51 type epoxy resin potting compound into a vacuum degassing machine and degas for 20 minutes under a pressure of -0.085MPa. Then pot the LED digital tube semi-finished product with the compound. After potting, let the semi-finished product stand for 15 minutes. S3, Low-temperature degassing: Place the LED digital tube semi-finished product after potting with encapsulant into an oven, raise the oven temperature from the low-temperature degassing temperature to 50℃ at a rate of 2℃ / min, and keep it at that temperature for 30 minutes; then raise the temperature to 60℃ and keep it at that temperature for 60 minutes. S4, Medium-temperature gel: After low-temperature defoaming, heat to 75℃ at a rate of 1.5℃ / min and keep warm for 1 hour; then heat to 85℃ and keep warm for 1 hour. S5. High-temperature curing: After the medium-temperature gelation is completed, the oven temperature is increased from the medium-temperature gelation temperature to 95℃ at a rate of 1.5℃ / min, and kept at this temperature for 3 hours. S6. Cooling and unloading: After high-temperature curing, cool to room temperature at a rate of 2℃ / min and remove the product.

[0025] In this embodiment, E51 is a standard bisphenol A type epoxy resin, which has high transparency (light transmittance > 85%), good resistance to yellowing, and excellent electrical insulation (volume resistivity > 10¹). 5 Features such as Ω·cm.

[0026] With a viscosity of 3000-5000 mPa·s, it is suitable for vacuum potting, has a low curing shrinkage rate (<1.5%), and effectively reduces internal stress.

[0027] In this embodiment, a pressure of -0.085 MPa is used for degassing, which effectively balances degassing efficiency and colloidal stability.

[0028] Excessive vacuum can cause low-boiling-point components to volatilize and alter the colloidal ratio, while insufficient vacuum can lead to incomplete degassing and the presence of residual microbubbles.

[0029] During the degassing process, the first 10 minutes are mainly used to remove large air bubbles, and the next 10 minutes are used to eliminate micron-sized small air bubbles. The appropriate time effectively avoids the problem of excessive time causing the viscosity of the colloid to increase and affecting its flowability.

[0030] In this embodiment, the heating rate during low-temperature defoaming is 2℃ / min, which keeps the internal temperature gradient of the colloid <5℃ / cm, thus avoiding thermal stress caused by rapid surface heating while the interior remains at a low temperature.

[0031] The viscosity of epoxy resin decreases most significantly in the 40-60℃ range, dropping from 5000 mPa·s to 800 mPa·s. A gradual increase in temperature allows for a smooth transition in viscosity. In this embodiment, the low-temperature bubble removal process involves holding the colloid at 50°C for 30 minutes. At this temperature, the colloid reaches its optimal fluidity, and the surface tension decreases from 45 mN / m to 38 mN / m, which is beneficial for bubble migration. The initiator begins to activate, forming a low molecular weight prepolymer, but the degree of crosslinking is <5%, which does not affect bubble removal. This facilitates the migration of bubbles from hidden areas such as the bottom of the chip and around the gold wires to the surface under the action of thermal convection.

[0032] Then, the temperature is raised from 50℃ to 60℃, the thermal motion rate of colloidal molecules increases by about 2.5 times, and the rising speed of bubbles is significantly improved; holding at this temperature for 60 minutes ensures that bubbles can be expelled as much as possible.

[0033] In this embodiment, during the warm gelation stage, the heating rate is reduced to 1.5℃ / min. The epoxy resin enters the critical gelation region at 70-85℃, and the rate is reduced from 2℃ / min to 1.5℃ / min, reducing thermal stress by 25% and protecting the initially formed network structure. The system is then kept at 75℃ for 1 hour. At 75℃, the E51 epoxy resin gels for approximately 90 minutes. The 1-hour holding time allows the system to reach the gel point without complete curing. The degree of crosslinking increases to 40-50%, and the colloid changes from a liquid state to a rubber state.

[0034] The molecular weight of the solidified product increases to tens of thousands, macroscopic fluidity disappears, and the position of the expelled bubbles is completely locked.

[0035] In this embodiment, during the warm gelation stage, the temperature is increased by 10°C from 75°C and kept at 85°C for 1 hour. The curing reaction rate constant k increases by about 2 times (Arrhenius equation), and the degree of crosslinking is increased to 60-70%.

[0036] The main shrinkage is completed in the rubber state, reducing the residual stress after the glass state.

[0037] In this embodiment, the epoxy resin Tg during the high-temperature curing stage is about 90-100℃. When the temperature is close to Tg, a rapid increase in temperature will cause a sudden change in free volume and generate stress.

[0038] This ensures that the temperature of the entire product rises evenly to the curing temperature, avoiding differences in curing degree between the edges and the center.

[0039] E51 epoxy resin requires approximately 2 hours to reach 90% curing at 95℃, and 3 hours of heat preservation is required to ensure full curing.

[0040] Prolonged heat preservation allows the remaining active groups to react completely, preventing performance changes caused by continued curing during use.

[0041] At high temperatures, the mobility of molecular chain segments is enhanced, which allows for the full relaxation of curing shrinkage stress and thermal stress.

[0042] In this embodiment, the slow cooling of the epoxy resin allows the thermal shrinkage difference between the epoxy resin and the metal / plastic parts to be released gradually, reducing the interfacial shear stress by about 60%. The cooling process is also a process of further stress relaxation, and the product performance tends to stabilize after being placed at room temperature.

[0043] Example 2 This invention discloses a multi-segment gradient baking and curing process for LED digital tubes, comprising the following steps: S1. Raw material preparation: Prepare semi-finished LED digital tubes with completed die bonding and wire bonding, and silicone potting compound; S2. Pre-treatment: Place the silicone potting compound into a vacuum degassing machine and degas for 25 minutes under a pressure of -0.09MPa. Then, pot the LED digital tube semi-finished product with the compound and let it stand for 20 minutes after potting. S3, Low-temperature degassing: Place the LED digital tube semi-finished product after potting with encapsulant into an oven, raise the oven temperature from the low-temperature degassing temperature to 55℃ at a rate of 2℃ / min, and keep it at that temperature for 1 hour; then raise the temperature to 65℃ and keep it at that temperature for 1 hour. S4, Medium-temperature gel: After low-temperature defoaming, heat to 75℃ at a rate of 1.5℃ / min and keep warm for 2 hours; then heat to 85℃ and keep warm for 1 hour. S5. High-temperature curing: After the medium-temperature gelation is completed, the oven temperature is increased from the medium-temperature gelation temperature to 100℃ at a rate of 1.5℃ / min, and kept at this temperature for 1.5h. Then, the temperature is increased to 120℃ and kept at this temperature for 1.5h. S6. Cooling and unloading: After high-temperature curing, cool to room temperature at a rate of 2℃ / min and remove the product.

[0044] In this embodiment, the silicone material has excellent high and low temperature resistance (-50℃~200℃), aging resistance, flexibility and light transmittance. Its low viscosity is suitable for vacuum potting, the curing shrinkage rate is <0.5%, which greatly reduces internal stress, the light transmittance is >90%, the refractive index is adjustable from 1.41 to 1.53, and it has good compatibility with LED chips.

[0045] In this embodiment, -0.09 MPa is the optimal balance point between degassing efficiency and colloidal stability. Under this vacuum level, the bubble volume increases by about 10 times, making it easier to remove.

[0046] To avoid excessively high vacuum levels causing the volatilization of low molecular weight components and altering the colloidal properties.

[0047] In this embodiment, the 25-minute degassing time is designed based on the characteristics of silicone gel. The silicone gel has a low viscosity (typically 1000-3000 mPa·s) and a fast bubble migration speed. The first 15 minutes remove macroscopic bubbles, and the last 10 minutes eliminate microscopic bubbles.

[0048] Ensure that the gas content inside the colloid is reduced to below 0.1%.

[0049] The surface tension of silicone is low, allowing it to fully spread and cover all the fine structures when left to stand.

[0050] The colloid forms good wetting with the LED chip, gold wire, and bracket surface, with a contact angle of <10°.

[0051] To ensure that the temperature of the colloid is consistent with the ambient temperature, and to avoid convection disturbances caused by temperature differences.

[0052] In this embodiment, during the low-temperature defoaming stage, the heating rate is 2℃ / min to ensure that the internal temperature gradient of the colloid is <3℃ / cm, thus avoiding excessive temperature difference between the surface and the center.

[0053] The viscosity of organosilicon decreases significantly in the 40-60℃ range (from 3000mPa·s to 500mPa·s), and a smooth transition in viscosity is achieved by gradually increasing the temperature.

[0054] Moderate heating increases bubble volume and reduces colloidal viscosity, thus promoting bubble buoyancy.

[0055] In the low-temperature defoaming stage of this embodiment, the organosilicon is kept at 55°C for 1 hour to achieve optimal flow dynamics, reduce viscosity to the minimum, and further reduce surface tension.

[0056] By utilizing the thermal convection effect, tiny air bubbles in hidden areas such as the bottom of the chip and around the gold wires migrate to the surface.

[0057] Silicone curing is sensitive to moisture; holding at 55℃ can remove trace amounts of moisture from the colloid.

[0058] In this embodiment, during the low-temperature defoaming stage, the temperature is increased from 55°C to 65°C, which increases the thermal motion rate of colloidal molecules by about 2 times and significantly improves the rising speed of bubbles. For bubbles with a diameter of 30 μm, the rising speed in the silicone gel at 65°C is about 0.3 mm / min.

[0059] A 60-minute heat treatment ensures that air bubbles at their maximum depth can be completely expelled.

[0060] In this embodiment, the heating rate during the thermogelation stage is reduced from 2℃ / min to 1.5℃ / min, reducing thermal shock by 25%, protecting the initially formed network structure, and slow heating makes the temperature of each part of the product more uniform.

[0061] In this embodiment, during the warm gelation stage, the silicone potting compound gels at 75°C for approximately 60-90 minutes, and the temperature is maintained for 2 hours to ensure complete passage through the gel point.

[0062] When the degree of crosslinking increases to 40-50%, the colloid changes from a liquid state to a rubber state.

[0063] The molecular weight of the solidified product increases significantly, macroscopic fluidity disappears, and the position of the expelled air bubbles is completely locked.

[0064] In the rubbery state, the molecular chain segments have sufficient mobility to release the curing shrinkage stress.

[0065] In this embodiment, the temperature is increased by 10°C during the warm gelation stage, and the temperature is kept at 85°C for 1 hour. This increases the curing reaction rate by about 1.8 times and the degree of crosslinking to 60-70%.

[0066] When the tensile strength reaches more than 70% of the final value, the elastic modulus gradually builds up, and the adhesion strength between the silicone and the substrate is enhanced at this temperature.

[0067] The main shrinkage is completed in the rubber state, reducing the residual stress after the glass state.

[0068] In this embodiment, the temperature difference between 85°C and 120°C during the high-temperature curing stage is relatively large. Maintaining a rate of 1.5°C / min avoids excessive thermal stress and ensures that the temperature of the entire product rises to the curing temperature uniformly, avoiding differences in curing degree between the edges and the center.

[0069] The curing rate of organosilicon is significantly accelerated at 100℃, and the degree of curing can reach more than 85% within 1.5 hours.

[0070] The Si-O-Si bond network is more complete, resulting in significantly improved mechanical properties and thermal stability.

[0071] It promotes the volatilization of low-molecular-weight byproducts (such as ethanol) generated during the curing process, thereby improving the purity of the material.

[0072] In this embodiment, during the high-temperature curing stage, the silicone curing reaction was basically completed at 120°C, with a curing degree >95%.

[0073] The glass transition temperature T_g is increased, the thermal stability is enhanced, and the thermal decomposition temperature is >300℃.

[0074] Tensile strength > 5 MPa, elongation at break > 150%.

[0075] At high temperatures, the mobility of molecular chain segments is enhanced, which allows for the full relaxation of curing shrinkage stress and thermal stress.

[0076] High temperatures promote chemical bonding between organosilicon and the substrate, improving interfacial adhesion strength and long-term stability.

[0077] In this embodiment, the CTE of the silicone during the cooling and unloading stage is much larger than that of the LED chip and the bracket material. Slow cooling allows the thermal shrinkage difference to be released gradually, avoiding microcracks or interface debonding caused by excessively rapid cooling.

[0078] Comparative Example 1 (Traditional single-stage high-temperature curing) Process: After the glue is poured, the temperature is raised to 85℃ at 5℃ / min, kept at that temperature for 4 hours, and then allowed to cool naturally.

[0079] Comparative Example 2 (Traditional Two-Stage Curing) Process: Hold at 85℃ for 2 hours, then directly heat to 95℃ and hold for 3 hours, followed by natural cooling.

[0080] Examples 1-2 and Comparative Examples 1-2 were tested.

[0081] The results are as follows: bubble rate 1.5% 3.5% 0.2% 0.1% internal stress 18MPa 13MPa 4MPa) 3MPa Curing uniformity Temperature difference between edge and center >10℃ Temperature difference between edge and center >9℃ Temperature difference between edge and center >3℃ Temperature difference between edge and center: 1.5℃ Optical uniformity The brightness difference between segments is 12%. Brightness difference between segments is 10%. 3% difference in brightness between segments Segment brightness difference 2% Adhesive layering ratio 2% 1.2% 0 0 Long-term reliability Yellowing becomes obvious after aging Yellowing becomes obvious after aging Excellent resistance to yellowing Excellent resistance to yellowing Temperature cycling performance (-40~105℃ 500 cycles) The image quality was poor, with a 30% attenuation and 51% of the samples showing short circuits and open circuits. The image quality was poor, with a 31% attenuation and 10% of the samples exhibiting short circuits or open circuits. No failures; packaging defect rate less than 0.8%. No failures; packaging defect rate less than 0.5%. A comparison of seven key indicators, including bubble rate, internal stress, and curing uniformity, shows that the overall performance of Examples 1 and 2 of this invention is superior to that of Comparative Examples 1 and 2, and the quality and reliability of the packaged products are greatly improved.

[0082] The bubble rate in the comparative example was 1.5%~3.5%, while that in the example was only 0.1%~0.2%, significantly reducing bubble defects; the delamination rate in the comparative example was 1.2%~2%, while neither example had glue delamination issues; the internal stress in the comparative example was 13~18MPa, while that in the example was reduced to 3~4MPa, significantly reducing internal residual stress and avoiding stress cracking risks at the source.

[0083] The temperature difference between the core and edge of the comparative example is >9~10℃, while the temperature difference of the example is only 1.5~3℃, resulting in more uniform curing and eliminating local under-curing / over-curing; the brightness difference between segments in the comparative example is 10%~12%, while that in the example is only 2%~3%, significantly improving the consistency of light emission.

[0084] The comparative sample showed severe yellowing after aging, while the example sample exhibited excellent resistance to yellowing and stable appearance over long-term use. In the comparative sample, the brightness decreased by 30% to 31%, and a large number of samples showed short circuits, open circuits, and missing images. In the example sample, there were no failed samples, the packaging defect rate was only 0.5% to 0.8%, and the packaging stability was extremely strong under extreme temperature change conditions.

[0085] As can be seen, this solution effectively improves the consistency of adhesive curing, reduces internal defects and residual stress, and provides better optical effects. At the same time, it significantly improves the reliability of products in terms of aging resistance and resistance to high and low temperature shocks.

[0086] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages.

[0087] Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

[0088] The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A multi-segment gradient baking and curing process for LED digital tubes, characterized in that, Includes the following steps: S1. Place the LED digital tube semi-finished product after potting glue into an oven and heat it to 45-65℃ at a rate of ≤3℃ / min. Keep it at the temperature for 2-5 hours under normal pressure or -0.02 to -0.05MPa slight negative pressure to carry out low-temperature debubbling. S2. After the low-temperature degassing is completed, the oven temperature is raised from the low-temperature degassing temperature to 70-100℃ at a uniform heating rate of ≤2℃ / min, and kept at this temperature for 2-4 hours to carry out medium-temperature gelation. S3. After the medium-temperature gelation is completed, the oven temperature is raised from the medium-temperature gelation temperature to 90-110℃ at a uniform heating rate of ≤2℃ / min, and kept at this temperature for 2-4 hours for high-temperature curing. S4. After high-temperature curing, reduce the oven temperature to room temperature at a uniform cooling rate of ≤3℃ / min, and then remove the product.

2. The LED digital tube multi-segment gradient baking and curing process according to claim 1, characterized in that: The heating process in step S1, the low-temperature defoaming stage, is as follows: heat the room temperature to 45-55℃, keep it at that temperature for 30 minutes to 1.5 hours, and then heat the room temperature to 55-65℃ and keep it at that temperature for 30 minutes to 1.5 hours.

3. The LED digital tube multi-segment gradient baking and curing process according to claim 1, characterized in that: The heating process in step S2, the warm gelation stage, is as follows: 70-80℃, hold for 1 to 2 hours; 80-90℃, hold for 1-2 hours.

4. The multi-segment gradient baking and curing process for LED digital tubes according to claim 1, characterized in that: After the glue-filling plate is completed in step S1, the LED digital tube semi-finished product is left to stand for 10-30 minutes before entering the baking and curing process.

5. The multi-segment gradient baking and curing process for LED digital tubes according to claim 1, characterized in that: The potting compound mentioned in step S1 is one of epoxy resin potting compound, addition-type silicone potting compound, or epoxy-silicone composite potting compound.

6. The LED digital tube multi-segment gradient baking and curing process according to claim 5, characterized in that: Before use, the potting compound needs to be degassed under vacuum at -0.08 to -0.09 MPa for 15-30 minutes to remove air bubbles generated during the stirring process.

7. The LED digital tube multi-segment gradient baking and curing process according to claim 1, characterized in that: In step S1, the temperature during the low-temperature degassing stage is 45-65℃, and the temperature is maintained for 1-3 hours.

8. The multi-segment gradient baking and curing process for LED digital tubes according to claim 1, characterized in that: In step S2, the temperature for the warm gelation stage is 70-85℃, and the temperature is maintained for 1.5-2 hours.

9. The multi-segment gradient baking and curing process for LED digital tubes according to claim 1, characterized in that: In step S3, the high-temperature curing stage is at a temperature of 85-110℃ and is maintained for 2-3.5 hours.