A multi-stage vacuum bake method for reducing moisture in a hermetically sealed product

Abstract

The application provides a multi-stage vacuum baking method for reducing water vapor in airtight packaging products, comprising the following steps: S1, placing an airtight packaging product to be baked in a vacuum oven, and performing first-stage baking at a preset baking temperature, and performing vacuum pumping and charging cycles during the baking process; S2, after the first-stage baking is completed, taking out the product after the temperature in the pre-baking vacuum oven is lowered to a preset temperature, and completing secondary inspection and point coating of silicone rubber within a limited time, and transferring the product to an oven of a sealing glove box; S3, performing second-stage baking at a preset baking temperature by using the oven of the sealing glove box, and performing vacuum pumping and charging cycles during the baking process; and S4, after the second-stage baking is completed, directly moving the product from the oven of the sealing equipment to the glove box for packaging operation.

Description

Technical Field

[0001] This invention relates to the field of hermetically sealed packaging technology for electronic components, and in particular to a multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products. Background Technology

[0002] Hermetically sealed packaging is a key technology for ensuring the long-term reliability of electronic components (such as hybrid integrated circuits, discrete semiconductor devices, microwave and RF components, etc.), and its core lies in controlling the moisture content within the packaging cavity. Research shows that moisture is one of the main causes of device failure: when moisture adheres to the chip surface, it forms conductive channels, leading to a shift in leakage parameters; when it condenses into liquid water or ice at low temperatures, it may accelerate metal corrosion, bond point detachment, or passivation layer cracking, ultimately causing functional failure. Currently, industry standards (such as GJB548C-2021 "Test Methods and Procedures for Microelectronic Devices" and GJB2438B-2017 "General Specifications for Hybrid Integrated Circuits") require hermetically sealed devices to have an internal moisture content ≤5000ppm at 100℃ (≤3000ppm for high-reliability products and aerospace-grade products) to prevent internal moisture condensation in environments below -40℃.

[0003] However, achieving the standard in actual production is significantly difficult, mainly due to the following reasons: 1. Complex sources of moisture: including water molecules adsorbed by packaging materials (ceramic tube shells, sealants, metal plating, etc.), assembly materials (silicone rubber, epoxy resin, conductive adhesive), residual moisture in the packaging environment, and external moisture intrusion into the interior due to sealing defects; 2. Limitations of traditional processes: although high-temperature baking can remove water molecules on the surface of the material, the removal rate of deep water molecules (such as inside the plating or colloid) is low.

[0004] Existing baking technologies generally face the challenge of balancing temperature and time: high temperatures can accelerate moisture removal but can easily damage heat-sensitive materials; low-temperature, long-duration baking is inefficient and makes it difficult to completely remove water molecules from the material. Therefore, there is an urgent need to develop an efficient and controllable baking method that can deeply remove moisture from the encapsulation while ensuring the integrity of the material. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products, addressing the shortcomings of the prior art.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products, comprising: S1, placing the hermetically sealed product to be baked in a vacuum oven, and performing a first stage of baking at a preset baking temperature, with vacuum pumping and filling cycles during the baking process; S2, after the first stage of baking is completed, cooling the product to a preset temperature in a pre-baking vacuum oven and removing it, completing a second inspection and applying silicone rubber within a limited time, and then transferring the product to the oven provided with the sealing glove box; S3, performing a second stage of baking at a preset baking temperature using the oven provided with the sealing glove box, with vacuum pumping and filling cycles during the baking process; S4, after the second stage of baking is completed, directly transferring the product from the oven provided with the sealing equipment to the glove box for sealing operations.

[0007] Furthermore, the preset baking temperature is 165℃.

[0008] Furthermore, the total baking time is 40 hours, of which the first baking time is ≥35 hours and the second baking time is ≥5 hours.

[0009] Furthermore, in step S2, the predetermined duration of the intermediate stop between the first and second baking stages is ≤30 minutes.

[0010] Furthermore, in step S2, the product temperature after baking is ≤50℃.

[0011] Furthermore, in step S1, the number of vacuum pumping cycles during the first stage of baking is ≥10; in step S3, the number of vacuum pumping cycles during the second stage of baking is ≥5.

[0012] Furthermore, before step S1, the process includes: preparing individual samples of the process additives to determine the sensitivity of various process additives to the effects of baking temperature and baking time.

[0013] Furthermore, hermetically sealed products are hybrid integrated circuits, semiconductor discrete devices, or microwave and radio frequency components.

[0014] Furthermore, the hermetically sealed product is a hermetically sealed product with a cavity volume ≤80cm³ and an internal moisture content ≤2000ppm after baking.

[0015] Furthermore, the parameters in six dimensions—baking mode, baking temperature, baking time, node control, vacuum environment, and product placement method—are adjusted according to product characteristics, equipment capabilities, and moisture requirements.

[0016] The beneficial effects of adopting the technical solution of this invention are that, through multi-stage baking, vacuum filling cycles, and strict node control, deeply adsorbed water molecules in the packaging material are effectively removed, ensuring that the internal moisture content of hybrid integrated circuit products with a cavity volume ≤80cm³ is stably controlled at ≤2000ppm, which is superior to the standard requirements. By establishing a process auxiliary material baking response model, the baking time of each stage can be precisely controlled. Under the premise of ensuring qualified moisture content, the baking temperature can be reasonably increased and the total baking time can be appropriately shortened, optimizing the production rhythm and reducing the operational pressure on employees. The baking mode, temperature, time, node control, vacuum environment, and product placement method can be finely adjusted according to different product characteristics, equipment capabilities, and internal moisture requirements, making it applicable to multiple product categories.

[0017] The advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram illustrating the sensitivity of various process auxiliary materials to baking temperature and baking time, as provided in the embodiments of the present invention.

[0020] Figure 2 This is a schematic diagram illustrating the moisture content of various process additives introduced into the product according to embodiments of the present invention.

[0021] Figure 3 This is a schematic diagram illustrating the effect of single-stage baking and two-stage baking on the internal moisture of the product, provided as an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram illustrating the effect of spot-applied silicone rubber on internal moisture in a product during secondary inspection, as provided in an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram illustrating the effect of the baking and removal temperatures in two stages, as provided in an embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram illustrating the impact of the two-stage baking node allocation on the internal moisture of the product and the impact of the product's placement method during baking on the internal moisture of the product, as provided in an embodiment of the present invention. Detailed Implementation

[0025] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0031] This invention provides a multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products, comprising: S1, placing the hermetically sealed product to be baked in a vacuum oven and performing a first stage of baking at a preset baking temperature, with vacuum pumping and filling cycles during the baking process; S2, after the first stage of baking is completed, cooling the product to a preset temperature in a pre-baking vacuum oven and removing it, completing a second inspection and applying silicone rubber within a limited time, and then transferring the product to the oven provided by the sealing glove box; S3, performing a second stage of baking at a preset baking temperature using the oven provided by the sealing glove box, with vacuum pumping and filling cycles during the baking process; S4, after the second stage of baking is completed, directly transferring the product from the oven provided by the sealing equipment to the glove box for sealing operations.

[0032] Furthermore, the preset baking temperature is 165℃.

[0033] Furthermore, the total baking time is 40 hours, of which the first baking time is ≥35 hours and the second baking time is ≥5 hours.

[0034] Furthermore, in step S2, the predetermined duration of the intermediate stop between the first and second baking stages is ≤30 minutes.

[0035] Furthermore, in step S2, the product temperature after baking is ≤50℃.

[0036] Furthermore, in step S1, the number of vacuum pumping cycles during the first stage of baking is ≥10; in step S3, the number of vacuum pumping cycles during the second stage of baking is ≥5.

[0037] Furthermore, before step S1, the process includes: preparing individual samples of the process additives to determine the sensitivity of various process additives to the effects of baking temperature and baking time.

[0038] Furthermore, hermetically sealed products are hybrid integrated circuits, semiconductor discrete devices, or microwave and radio frequency components.

[0039] Furthermore, the hermetically sealed product is a hermetically sealed product with a cavity volume ≤80cm³ and an internal moisture content ≤2000ppm after baking.

[0040] Furthermore, the parameters in six dimensions—baking mode, baking temperature, baking time, node control, vacuum environment, and product placement method—are adjusted according to product characteristics, equipment capabilities, and moisture requirements.

[0041] Based on product characteristics, equipment capabilities, and internal moisture requirements, the parameters can be refined and adjusted in the following six dimensions: Baking mode: single-stage or two-stage; Baking temperature: can be adjusted according to the temperature resistance characteristics of the material; Baking time: The duration of each stage can be allocated as needed; Node control: The dwell time during stage transitions and the removal temperature are adjustable; Vacuum environment: The number of vacuum pumping cycles can be increased or decreased; Product placement method: The placement density and orientation can be optimized.

[0042] The beneficial effects of adopting the technical solution of this invention are that, through multi-stage baking, vacuum filling cycles, and strict node control, deeply adsorbed water molecules in the packaging material are effectively removed, ensuring that the internal moisture content of hybrid integrated circuit products with a cavity volume ≤80cm³ is stably controlled at ≤2000ppm, which is superior to the standard requirements. By establishing a process auxiliary material baking response model, the baking time of each stage can be precisely controlled. Under the premise of ensuring qualified moisture content, the baking temperature can be reasonably increased and the total baking time can be appropriately shortened, optimizing the production rhythm and reducing the operational pressure on employees. The baking mode, temperature, time, node control, vacuum environment, and product placement method can be finely adjusted according to different product characteristics, equipment capabilities, and internal moisture requirements, making it applicable to multiple product categories.

[0043] This invention provides a multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products. It aims to solve the "temperature-time" contradiction and the difficulty in removing deep-seated moisture in traditional baking through multi-dimensional process optimization, achieving the following objectives: For hybrid integrated circuit products with a cavity volume ≤80cm³, achieving stable control of internal moisture ≤2000ppm; while ensuring that the internal moisture of the product is qualified and controllable, reasonably increasing the baking temperature and appropriately shortening the baking time to optimize the production rhythm; and achieving applicability to multiple product categories.

[0044] This invention, through extensive experimental data, reveals and resolves a long-neglected "contradiction" and "new problem" in the hermetically sealed baking process, and provides a quantitative solution.

[0045] Improvement point 1: The contradiction between "baking and moisture" was identified and an "anti-moisture" process system was established. The logic of traditional methods is that "the higher the temperature and the longer the time, the better the water removal," but this invention, through experiments (…), Figure 3 , Figure 4 , Figure 5 )Discover: After prolonged high-temperature baking or two-stage baking, materials (especially white film and flux-containing solder) will experience severe "moisture absorption" when paused midway or removed at high temperatures, causing moisture to rise instead of decrease (e.g.) Figure 3 The concentration of white film increased from 1461 ppm to 2410 ppm.

[0046] Solution of the present invention Node control: Clearly limit the "intermediate dwell time to ≤30min" (i.e., rapid transfer to reduce the moisture absorption window).

[0047] Temperature control upon removal: Clearly define the removal temperature as "≤50℃" (meaning it must be cooled to a temperature far below that of traditional processes within the oven before removal to prevent moisture absorption from high temperatures encountering cold air; see [link to relevant documentation]). Figure 5 data).

[0048] Multi-stage time allocation: clearly defined "first stage baking time ≥ 35h, second stage baking time ≥ 5h" (total time 40h, with most of the time used for pre-desorption and a short final time for finishing).

[0049] Improvement point two: Differentiated treatment strategy for "high-risk materials" This invention does not treat all materials the same way, but proposes a baking scheme tailored to the sensitivity of different additives (see [link]). Figure 1 , Figure 2 ).

[0050] The moisture content of the white film (2933 ppm) is more than 10 times that of the solder sheet (275 ppm), and it is extremely sensitive to both stages of baking. Figure 3 (Severe moisture return). Conductive adhesive and blue adhesive, on the other hand, perform best with single-stage baking.

[0051] Solution (specific technical features) This invention prepares individual samples for each process auxiliary material (especially white film and flux-containing solder), measures its "temperature-time sensitivity" and "intrinsic moisture content", and determines whether to use two-stage baking based on the results.

[0052] For high-risk materials (white film / flux), a baking scheme of "high temperature (165℃) + long time (≥35h pre-baking) + short time finishing (5h) + low temperature removal (≤50℃)" is adopted.

[0053] Improvement point 3: Synergistic optimization of inverted baking and airflow layout See Figure 6 Data shows that the product placement method (upright vs. inverted) significantly affects the moisture escape path. Upright placement is more effective for shorter pre-baking times; however, when the pre-baking time is ≥25 hours, inverted baking significantly surpasses it in dehumidification. Figure 6 When pre-dried for 35 hours and then fed into the machine for 5 hours, the ppm value was 177 ppm when inverted and 232 ppm when upright.

[0054] Solution (specific technical features) When the pre-baking time is ≥25h and the second-stage baking time is ≤5h, the product should be placed upside down.

[0055] Simultaneously, by combining the number of vacuum pumping cycles (≥10 times and ≥5 times), and through the synergy of physical airflow and gravity direction, deep-level water vapor desorption is forced.

[0056] Improvement point four: Auxiliary water removal strategy based on "9187 material" See Figure 4 Data shows that certain auxiliary materials (such as 9187 material) are introduced into the process, but they themselves have the function of assisting in drying or blocking moisture.

[0057] Solution (specific technical features) In interference source control, the dispensing process is identified and utilized: During secondary inspection, the silicone rubber (9187) applied can significantly reduce moisture content (2103ppm→829ppm) when combined with a short (0.5h) two-stage baking process; however, this benefit disappears if the baking time is 6h. Therefore, the baking time after secondary dispensing should be controlled to approximately 0.5h.

[0058] This invention achieves its goals through the systematic analysis and control of the following core influencing factors: Establish a baking response model: determine the response relationship of various process materials and auxiliary materials to baking temperature and time; Dynamic time control: Implement multi-stage baking and optimize the time allocation for each stage; Interference source control: Control interference from dispensing during secondary inspection and temperature interference when the product is removed; Optimization of vacuum environment and airflow layout during baking: Optimize product placement.

[0059] The specific verification process is as follows: Prepare individual samples for each type of process auxiliary material to determine the sensitivity of each type of process auxiliary material to the effects of baking temperature and baking time; Prepare individual samples for each type of process auxiliary material to determine the moisture content introduced into the product by each type of process auxiliary material. Multi-stage baking verification was conducted to determine the impact of single-stage baking versus two-stage baking on internal moisture content of the product. Determine the impact of spot-applied silicone rubber on internal moisture vapor in the product during secondary inspection; Determine the effect of the baking temperature on the two stages of baking; Determine the impact of the two-stage baking node allocation on the internal moisture of the product; Determine the impact of product placement during baking on internal moisture levels.

[0060] Based on the above verification results, the present invention provides a typical implementation method: A multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products includes the following steps: First stage of baking Place the hermetically sealed product to be baked in a vacuum oven and bake it at 165℃ for the first stage for ≥35 hours. The number of vacuum pumping cycles during the baking process is ≥10. Phase transition After the first stage of baking is completed, the product is cooled to the preset temperature in the pre-baking vacuum oven and then taken out. After completing the second inspection and applying silicone rubber within a limited time, the product is transferred to the oven provided with the sealing glove box and the dwell time is ≤30 minutes. Second stage of baking The second stage of baking is carried out at 165℃ for ≥5 hours, with the number of vacuum pumping cycles ≥5 times during the baking process. After the second stage of baking is completed, the equipment is moved directly from the oven on its own to the glove box for sealing.

[0061] This invention provides a multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products. This method offers a controllable, multi-stage vacuum baking approach to reduce internal moisture in hermetically sealed products, aiming to solve problems such as the "temperature-time" contradiction and the difficulty in removing deep-seated moisture in traditional baking processes through multi-dimensional process optimization. Specifically, this is achieved by addressing the following core influencing factors: 1. Establish a baking response model (moisture introduced by process materials and auxiliary materials; baking response model of process materials and auxiliary materials to baking time and temperature).

[0062] 2. Dynamic control of time nodes (multi-stage baking; time allocation for each stage).

[0063] 3. Control of interference sources (interference from dispensing during secondary product inspection; interference from temperature when the product is removed).

[0064] 4. Vacuum environment and airflow layout during baking (optimization of product placement).

[0065] This invention closely integrates various influencing factors and has undergone multi-dimensional optimization. Firstly, it achieves compatibility with cavity volumes ≤80cm². 3 The invention provides two main benefits: firstly, stable control of internal moisture content in hybrid integrated circuit products to ≤2000ppm; secondly, under the premise of ensuring that the internal moisture content of the product is qualified and controllable, reasonably increasing the baking temperature and appropriately shortening the baking time, refining the baking conditions, optimizing the production rhythm, and reducing the operational pressure on employees; and thirdly, the invention can be combined with different product characteristics and technical details to further refine and adjust multi-dimensional parameters to achieve applicability to multiple product categories.

[0066] The specific verification process and content during the implementation of this invention are as follows: 1. Prepare individual samples for each type of process auxiliary material to determine the sensitivity of each type of process auxiliary material to the effects of baking temperature and baking time (see attached). Figure 1 (This is a partial record).

[0067] 2. Prepare individual samples for each type of process auxiliary material to determine the moisture content introduced into the product by each type of process auxiliary material (see attached sample). Figure 2 ).

[0068] 3. Multi-stage baking verification to determine the impact of single-stage baking versus two-stage baking on internal moisture content of the product (moisture absorption of auxiliary materials) (see attached). Figure 3 ).

[0069] 4. Determine the impact of applying silicone rubber during secondary inspection on internal moisture in the product (moisture absorption during silicone curing process) (see attached document). Figure 4 ).

[0070] 5. Determine the effect of the baking temperature on the two stages of baking (see appendix) Figure 5 ).

[0071] 6. Determine the impact of the two-stage baking node allocation on the internal moisture of the product (see appendix) Figure 6 ).

[0072] 7. Determine the impact of product placement during baking on internal moisture content (see appendix). Figure 6 ).

[0073] Specifically, each process auxiliary material used in the hermetically sealed packaging product is prepared independently, and its water vapor desorption sensitivity at preset temperature and time is measured. Based on the measurement results, the auxiliary materials are divided into high-sensitivity materials and low-sensitivity materials.

[0074] Based on the classification results, the product is subjected to two-stage vacuum baking, wherein: The first stage of baking is at a temperature of 155℃-165℃, with a baking time of ≥35 hours, and at least 10 vacuum-nitrogen-filling cycles are performed during this process.

[0075] After the first stage of baking is completed, the product is cooled to the preset temperature in the pre-baking vacuum oven and then taken out. After completing the second inspection and applying silicone rubber within a limited time, the product is transferred to the oven provided with the sealing glove box.

[0076] The second stage of baking is at a temperature of 155℃-165℃, with a baking time of ≥5 hours, and at least 5 vacuum-nitrogen-filling cycles are performed during this process.

[0077] After the second stage of baking is completed, the equipment is moved directly from the oven on its own to the glove box for sealing.

[0078] During the first and second baking processes, the product is placed upside down so that the opening of the packaging cavity faces downwards.

[0079] Figure 1 The effect of single-stage baking (135-165℃, different times) on moisture content Variables: Baking temperature (135 / 150 / 165℃), baking time (30 / 45h).

[0080] Key results: #17 (150℃ / 30h) had the highest moisture content, reaching 2933ppm; #22 (165℃ / 45h) had the lowest moisture content, at 1022ppm.

[0081] Meaning: In single-stage baking, the higher the temperature and the longer the time, the better the moisture removal effect; however, even at the highest temperature and the longest time, the moisture content is still above 1000ppm, indicating that the efficiency of single-stage baking is limited.

[0082] Figure 1 The study demonstrates the moisture content (ppm) of the white film material under different combinations of baking temperature (T) and baking time (t).

[0083] Vertical axis: Moisture content (ppm, the lower the value, the better the drying effect).

[0084] Horizontal axis 1 (baking temperature): 135℃, 150℃, 165℃.

[0085] Horizontal axis 2 (baking time): 30h, 45h.

[0086] Data Summary: Product ID: 18#. Temperature (°C): 135. Duration (h): 30. Moisture content (ppm): 2799.

[0087] Product ID: 17#. Temperature (°C): 150. Duration (h): 30. Moisture content (ppm): 2933.

[0088] Product ID: 20#. Temperature (°C): 150. Duration (h): 45. Moisture content (ppm): 1331.

[0089] Product ID: 19#. Temperature (°C): 135. Duration (h): 45. Moisture content (ppm): 1461.

[0090] Product ID: 22#. Temperature (°C): 165. Duration (h): 45. Moisture content (ppm): 1022.

[0091] Product ID: 21#. Temperature (°C): 150. Duration (h): 30. Moisture content (ppm): 1082.

[0092] Baking time is a key variable in reducing the moisture content of the white film. When the baking time is 30 hours, the moisture content at all temperatures is above 1000 ppm, and the moisture content is close to 3000 ppm when the baking temperature is 135℃, resulting in extremely poor drying effect.

[0093] When the baking temperature remains constant, but the baking time is extended from 30 hours to 45 hours, the moisture content does not change significantly.

[0094] 135℃: 2933ppm→2799ppm, a decrease of about 4.6%.

[0095] 150℃: 1461ppm → 1331ppm, a decrease of about 8.9%.

[0096] 165℃ (data for 45 hours only): 1022ppm, the lowest value in this experiment.

[0097] Conclusion: Simply extending the baking time cannot solve the problem of drying the white film; the baking time must be significantly increased to effectively reduce the moisture content.

[0098] The effect of baking temperature: given sufficient time, higher temperatures are more advantageous.

[0099] With a short baking time of 30 hours, the temperature increased from 135℃ to 150℃, and the moisture content decreased (2933-1461ppm), indicating that high temperature can effectively remove moisture from the inside of the white film in a short time.

[0100] Under a long baking time of 45 hours, the higher the temperature, the lower the moisture content: 135℃ (2799ppm) > 150℃ (1331ppm) > 165℃ (1022ppm). This indicates that under sufficient time, higher baking temperature can accelerate moisture diffusion and improve drying efficiency.

[0101] Optimal process combination In this experiment, the combination of baking at 165℃ for 45h had the lowest moisture content (1022ppm), which is the optimal process for white film material; followed by 165℃ / 30h (1082ppm) and 150℃ / 45h (1331ppm), while all processes at 135℃ could not effectively reduce the moisture content.

[0102] Process optimization suggestions The core adjustments for white film materials are as follows: the baking temperature must be increased to 150℃ or above, as the conventional process at 135℃ is almost ineffective for white film; high-temperature baking at 150-165℃ should be given priority, and long or short baking times should be matched according to product characteristics, equipment capacity, internal moisture requirements and other influencing factors to avoid the low efficiency caused by low-temperature baking.

[0103] Process risk control: The heat resistance of the white film needs to be assessed for high-temperature and long-duration baking to avoid material aging and performance degradation; after baking, it is necessary to use a low-humidity environment for slow cooling to avoid rapid moisture re-dampness caused by high-temperature removal (it is recommended to cool to 30-60℃ before removal).

[0104] Alternative solutions: If prolonged high-temperature baking has a significant impact on material performance, alternative membrane materials with low moisture absorption may be evaluated, or the pretreatment process of the white film may be optimized (such as pre-drying or surface modification).

[0105] Figure 2 Comparison of initial moisture content of different packaging materials Variable: Material type (blue glue, conductive glue, white film, solder sheet / flux).

[0106] Key results: The white film had the highest moisture content (2933 ppm), while the solder sheet / flux (33#) had the lowest moisture content (275 ppm); the moisture content of the blue glue, conductive glue, and solder sheet / flux decreased in that order.

[0107] Meaning: The water absorption of the materials varies greatly. The white film is a high-risk, high-moisture material, while the solder-related materials have lower initial moisture content. This explains why subsequent experiments mostly focused on optimizing the baking process for high-moisture materials such as the white film.

[0108] Figure 2 A comparison of the moisture content (ppm) of different packaging materials under the same baking process.

[0109] Vertical axis: Moisture content (ppm, parts per million; the lower the value, the lower the moisture content after drying, and the better the processing performance). Horizontal axis: Material type (several auxiliary materials commonly used in semiconductor / electronic packaging).

[0110] Data Summary: Product Number: 1#. Material Type: Blue Glue. Moisture Content (ppm): 609.

[0111] Product ID: 9#. Material type: Conductive adhesive. Moisture content (ppm): 437.

[0112] Product ID: 17#. Material type: White film. Moisture content (ppm): 2933.

[0113] Item No.: 28#. Material type: Solder sheet + flux. Moisture content (ppm): 1706.

[0114] Item No.: 33#. Material Type: Solder Sheet. Moisture Content (ppm): 275.

[0115] The materials vary greatly in moisture content and can be divided into three tiers. Low moisture content tier (easy to dry, <700ppm): Solder sheet (275ppm) < Conductive adhesive (437ppm) < Blue adhesive (609ppm).

[0116] The three materials all had low moisture content after baking, indicating that the materials themselves had low moisture absorption or that internal moisture was easy to expel, and that they were well adapted to the drying process.

[0117] Medium moisture content range (1000-2000ppm): Solder sheet + flux (1706ppm).

[0118] The addition of flux significantly increased the overall moisture content, indicating that flux components (such as rosin and activators) have strong hygroscopic properties or are prone to retaining moisture during the baking process, which greatly increases the difficulty of drying.

[0119] High moisture content category (>2500ppm, extremely difficult to dry): white film (2933ppm).

[0120] The white film was the material with the highest moisture content in this experiment, indicating that its material structure or composition is extremely hygroscopic and the moisture is difficult to remove through conventional baking processes, making it a key challenge for process optimization.

[0121] Key Comparison: The Effect of Flux on Moisture Content of White Film / Solder Sheet The solder sheet itself has a moisture content of only 275 ppm, but after adding flux, it soars to 1706 ppm, an increase of more than 5 times.

[0122] The moisture content of the white film (2933ppm) is more than 10 times that of the pure solder sheet, and even without flux, it has a higher moisture content than the solder sheet with flux.

[0123] Conclusion: Flux is the key factor affecting the moisture content of the solder sheet system, and the hygroscopic properties of the white film itself are the core reason for its high moisture content.

[0124] Process optimization suggestions Low moisture content materials (pure solder sheet, conductive adhesive, blue glue) The existing baking process already meets the low moisture content requirement and does not require significant adjustments. The moisture content can be further reduced by optimizing the removal temperature (e.g., lowering it to 30-60℃) to prevent moisture absorption.

[0125] For flux-containing solder sheet systems: prioritize optimizing flux selection, choosing fluxes with low moisture absorption and low residue; consider extending the pre-baking time and adjusting the baking temperature profile to specifically remove moisture and solvents from the flux.

[0126] White film: The process needs to be optimized separately. You can try extending the baking time, using segmented baking + low humidity environment cooling, or evaluating replacing it with a low moisture absorption membrane material.

[0127] The white film has poor tolerance to the two-stage baking + dwell process. It is recommended to give priority to single-stage high-temperature baking to reduce the risk of moisture re-entry.

[0128] Figure 3 Moisture content comparison of different baking processes and ingredient combinations Variables: Baking process (single-stage baking / two-stage baking (0.5h / 6h dwell time)), materials (white film, solder / flux, blue glue, conductive glue).

[0129] Key results: The white film (19# / 23# / 24#) had the highest overall moisture content, remaining at 1400-2400 ppm even after two stages of baking. The blue adhesive (3# / 7# / 8#) had moderate moisture content, still ranging from 237 to 1410 ppm after two stages of baking. The conductive adhesive (11# / 15# / 16# / 37#) had the lowest moisture content, which could be as low as 163 ppm after process optimization. The solder / flux (30# / 32#) had intermediate moisture content, still exceeding 1200 ppm after two stages of baking.

[0130] Meaning: The inherent moisture content of a material is a key factor affecting the final result. For high-moisture materials (such as white films), the effect of optimizing the baking process alone is limited.

[0131] Two-stage baking is more effective at removing moisture than single-stage baking, and the longer the residence time, the more thorough the moisture removal (e.g., white film moisture content changes from 1461 ppm to 2103 / 2410 ppm). Note that the moisture content of the white film actually increases after two-stage baking, indicating that the white film releases more moisture at high temperatures, or that the two-stage baking conditions are not favorable for the white film, and subsequent processes need to be adjusted accordingly.

[0132] Figure 3 The study demonstrates the moisture content (ppm) of different materials (encapsulation auxiliary materials) under three baking processes.

[0133] Vertical axis: Moisture content (ppm, the lower the value, the better the drying effect).

[0134] Horizontal axis 1 (baking process): single-stage baking (150℃ / 30h), two-stage baking (0.5h dwell time), two-stage baking (6h dwell time).

[0135] Horizontal axis 2 (material type): Legend: White. Material type: White film.

[0136] Legend: Light yellow. Material type: Solder sheet / flux.

[0137] Legend: Cyan. Material type: Blue glue.

[0138] Legend: Dark gray. Material type: Conductive adhesive.

[0139] Legend: Light gray. Material type: Solder sheet.

[0140] Complete data summary: Product Number: 19#. Material Type: White Film. Baking Process: Single-stage baking. Moisture Content (ppm): 1461.

[0141] Item No.: 30#. Material Type: Solder sheet / flux. Baking Process: Single-stage baking. Moisture Content (ppm): 120g.

[0142] Product Number: 3#. Material Type: Blue Gum. Baking Process: Single-stage baking. Moisture Content (ppm): 237.

[0143] Product ID: 11#. Material type: Conductive adhesive. Baking process: Single-stage baking. Moisture content (ppm): 203.

[0144] Item No.: 35#. Material Type: Solder Sheet. Baking Process: Single-stage baking. Moisture Content (ppm): 163.

[0145] Product Number: 23#. Material Type: White film. Baking Process: Two-stage baking (0.5h dwell time). Moisture Content (ppm): 2103.

[0146] Product Number: 7#. Material Type: Blue Glue. Baking Process: Two-stage baking (0.5h dwell time). Moisture Content (ppm): 1104.

[0147] Product Number: 15#. Material Type: Conductive Adhesive. Baking Process: Two-stage baking (0.5h dwell time). Moisture Content (ppm): 308.

[0148] Product Number: 24#. Material Type: White film. Baking Process: Two-stage baking (6-hour dwell time). Moisture Content (ppm): 2410.

[0149] Item No.: 32#. Material Type: Solder sheet / flux. Baking Process: Two-stage baking (6 hours). Moisture Content (ppm): 2135.

[0150] Product Number: 8#. Material Type: Blue Gum. Baking Process: Two-stage baking (6 hours). Moisture Content (ppm): 1410.

[0151] Product Number: 16#. Material Type: Conductive Adhesive. Baking Process: Two-stage baking (6 hours). Moisture Content (ppm): 702.

[0152] Item No.: 37#. Material Type: Solder sheet. Baking Process: Two-stage baking (6 hours). Moisture Content (ppm): 204.

[0153] The moisture resistance and drying difficulty of the materials themselves vary greatly. The moisture content of different materials varies greatly, and they are listed from low to high.

[0154] Optimal setting (<300ppm under single-stage baking): Conductive adhesive (203ppm), solder sheet (163ppm), blue adhesive (237ppm).

[0155] Medium range (1000-1500ppm): Solder sheet / flux (1209ppm), solder sheet (1461ppm).

[0156] High difficulty level (>2000ppm): Solder sheet (two-stage baking, 0.5h / 6h), Solder sheet / flux (two-stage baking, 6h).

[0157] Conclusion: Conductive adhesive, solder sheets (some specifications), and blue adhesive have lower initial moisture content and are much easier to dry than white film and solder combinations containing flux.

[0158] Baking processes have completely opposite effects on different materials. White film / solder sheet + flux: Two-stage baking (whether it is 0.5h or 6h) will cause the moisture content to increase significantly. Single-stage baking has the best effect (1461ppm vs 2103 / 2410ppm), indicating that multiple baking and holding will cause this type of material to become severely damp.

[0159] Blue glue: Similarly, the moisture content increases significantly after two-stage baking. Single-stage baking (237ppm) is far superior to the two-stage process (1104 / 1410ppm). The longer the residence time, the higher the moisture content.

[0160] Conductive adhesive: It showed a certain degree of resistance to moisture re-entry. There was little difference between a single section (203ppm) and two sections after 0.5h (308ppm), but the moisture content still increased significantly after 6h (702ppm).

[0161] Special case: 37# solder sheet: The moisture content was only 204ppm after two-stage baking and 6h, which is close to 163ppm after single-stage baking. This indicates that some specifications of solder sheets can maintain a low moisture content under two-stage process, which may be related to the material formula or process details.

[0162] Optimal process-material combination In this experiment, the solder sheet (35#, 163ppm) under single-stage baking (150℃ / 30h) had the lowest moisture content and was the best combination overall; followed by conductive adhesive (203ppm) and blue adhesive (237ppm) under the same process.

[0163] Process optimization suggestions For materials with high moisture content (solder sheets / flux, white film): a single-stage baking process should be preferred to avoid two-stage baking plus a pause, which could lead to excessive moisture content due to moisture reabsorption. Based on the single-stage baking process, the removal temperature can be optimized (e.g., reduced to 30-60℃) to reduce moisture absorption and further lower the moisture content.

[0164] Blue glue: Single-stage baking yields the best results; two-stage baking will cause the moisture content to spike, so it should be avoided.

[0165] Figure 4 The effect of using "9187 material" on post-baking moisture content. Variables: Baking process (single-stage / two-stage (0.5h / 6h dwell time)), whether or not 9187 material is added.

[0166] Key results: Samples without 9187 had significantly higher moisture content (1461-2410 ppm), while the moisture content decreased significantly (829-1888 ppm) after adding 9187; and longer retention time was not necessarily better, with a more obvious reduction effect after 0.5 h (1278 ppm-829 ppm), while after 6 h, the moisture content increased from 829 ppm to 1888 ppm.

[0167] Meaning: Material 9187 has a significant auxiliary dehydration effect, possibly acting as a desiccant or moisture barrier, effectively reducing the overall moisture content, and is one of the key materials for process optimization.

[0168] Figure 4 The effects of different baking processes and the presence or absence of 9187 material (presumably some kind of adhesive / coating) on ​​the final moisture content (ppm) are demonstrated.

[0169] Basic information about charts Vertical axis: Moisture content (ppm, the lower the value, the better the drying effect).

[0170] Horizontal axis (process type): single-stage baking, two-stage baking (0.5h dwell time), two-stage baking (6h dwell time).

[0171] Legend (variables): Orange bars: No 9187 material. Blue-green bars: 9187 material present.

[0172] Data Summary: Product ID: 19#. Process type: Single-stage baking. Contains 9187: No. Moisture content (ppm): 1461.

[0173] Product ID: 25#. Process type: Single-stage baking. Contains 9187: Yes. Moisture content (ppm): 1278.

[0174] Product ID: 23#. Process type: Two-stage baking (0.5h dwell time). Contains 9187: No. Moisture content (ppm): 2103.

[0175] Product ID: 26#. Process type: Two-stage baking (0.5h dwell time). Contains 9187: Yes. Moisture content (ppm): 829.

[0176] Product ID: 24#. Process type: Two-stage baking (6-hour dwell time). Contains 9187: No. Moisture content (ppm): 2410.

[0177] Product ID: 27#. Process type: Two-stage baking (6-hour dwell time). Contains 9187: Yes. Moisture content (ppm): 1888.

[0178] The effect of 9187 material: significantly reduces moisture content. In all process types, the moisture content of samples containing 9187 material was much lower than that of samples without 9187.

[0179] First stage of baking: 1461ppm-1278ppm, a decrease of about 12.5%.

[0180] Two-stage baking (0.5h dwell time): 2103ppm-829ppm, a decrease of up to 60.6%.

[0181] Two-stage baking (6-hour stay): 2410ppm-1888ppm, a decrease of approximately 21.7%.

[0182] Conclusion: The 9187 material itself may have better moisture resistance / lower initial moisture content, or be more conducive to moisture removal during baking, which are key positive factors affecting moisture content.

[0183] Effect of baking process: Without 9187, two-stage baking actually increases the moisture content.

[0184] Samples without 9187: single-stage baking (1461ppm) < two-stage baking (0.5h dwell time, 2103ppm) < two-stage baking (6h dwell time, 2410ppm), moisture content continued to increase with prolonged dwell time.

[0185] For samples containing 9187: two-stage baking (0.5h dwell time, 829ppm) < one-stage baking (1278ppm) < two-stage baking (6h dwell time, 1888ppm). Two-stage baking with a dwell time of 0.5h yielded the best results. Excessive dwell time led to a rebound in moisture content.

[0186] Conclusion: For materials without 9187, two-stage baking plus a stoppage will cause moisture reabsorption; for materials containing 9187, the advantage is only shown in two-stage baking with a short stoppage (0.5h), and the process benefits will be negated if the stoppage time is too long.

[0187] Optimal process combination In this experiment, the material containing 9187 with two-stage baking (0.5h stay) had the lowest moisture content (829ppm), which was the best drying effect; while for the material without 9187, one-stage baking was the relatively optimal choice.

[0188] If using materials containing 9187: prioritize a two-stage baking process with a short dwell time (0.5h) to avoid excessively long dwell times (e.g., 6h) and prevent moisture content rebound.

[0189] If 9187 material is not included: it is not recommended to use the two-stage baking process. Simply use the one-stage baking process to reduce the risk of moisture absorption.

[0190] The "material properties (whether it contains 9187)" can be used as a pre-variable to select the baking method and removal temperature in a targeted manner to minimize the moisture content.

[0191] Figure 5 The effect of temperature on moisture content after baking Variable: Temperature after baking (90 / 60 / 45 / 30℃).

[0192] Key findings: The highest moisture content (815 ppm) was observed at 90°C. As the temperature decreased, the moisture content continued to decline, reaching 648 ppm at 30°C. The moisture content change became more gradual below 60°C.

[0193] Meaning: High temperature removal can cause samples to "reabsorb moisture" - when taken out of the oven, the high temperature sample comes into contact with moisture in the air and will quickly absorb moisture, causing the moisture to rebound; therefore, it is necessary to slowly cool down to a lower temperature after baking before taking it out to avoid moisture reabsorption.

[0194] Figure 5 The changes in material moisture content (in ppm) are shown at different baking and removal temperatures.

[0195] Horizontal axis: Temperature after baking (°C), with four gradients set: 90°C, 60°C, 45°C, and 30°C (Note: No data available for 75°C). Vertical axis: Moisture content (ppm, parts per million; lower values ​​indicate better drying results).

[0196] Product No. 38#. Temperature at removal (°C): 90. Moisture content (ppm): 815.

[0197] Product No. 41#. Temperature at removal (°C): 60. Moisture content (ppm): 658.

[0198] Product No. 42#. Temperature at removal (°C): 45. Moisture content (ppm): 661.

[0199] Product No. 43#. Temperature at removal (°C): 30. Moisture content (ppm): 648.

[0200] Overall trend: Lowering the extraction temperature leads to a significant decrease in moisture content. From 90℃ to 60℃, the moisture content dropped sharply from 815ppm to 658ppm, a decrease of about 19%; when it continued to decrease to 45℃ and 30℃, the moisture content remained at a low level of about 650ppm, and the change became gradual.

[0201] This indicates that removing the material from the oven at high temperatures after baking will cause it to quickly absorb moisture from the air, resulting in a rebound in moisture content. Lowering the removal temperature (removing the material after it has cooled down) can effectively reduce moisture absorption and maintain a dry state.

[0202] Key turning point: 60℃ is a clear dividing line. Above 60℃ (90℃): The moisture content remains high, and the phenomenon of dampness is serious.

[0203] At temperatures below or equal to 60℃ (60℃, 45℃, 30℃): the moisture content remains stable at around 650ppm, and reaches a minimum of 648ppm at 30℃.

[0204] Cooling and removing the product at temperatures below 60°C can significantly suppress moisture reabsorption, and further cooling (such as to 30°C) still has a slight optimization effect.

[0205] Interpretation of the significance of the process These types of experiments are typically used to optimize the baking process for semiconductor packaging and electronic components. If the material is removed directly at high temperature after baking, it will rapidly absorb moisture from the environment due to the temperature difference, resulting in excessive moisture content. However, removing it after cooling allows the moisture state on the surface and inside of the material to be stabilized, reducing moisture re-entry and improving the reliability of the drying process.

[0206] The optimal process point is when the moisture content is lowest (648ppm) when the product is taken out at 30℃, which is the parameter with the best drying effect in this experiment.

[0207] Balancing cost and effectiveness: The moisture content (658ppm) when removed at 60℃ differs from that at 30℃ by only about 10ppm, indicating that in actual production, a cooling temperature of around 60℃ is sufficient to balance drying effect and production efficiency, without the need for excessive cooling.

[0208] Optimizing the removal temperature can further consolidate the low moisture content results achieved by "extending the pre-baking time and inverting the baking process" and prevent the moisture content from rebounding due to high temperature removal.

[0209] Figure 6 Moisture optimization process in staged baking (pre-baking + resting + baking in machine) Variables: Baking process (pre-baking time, resting time, baking time), placement method (upright / upside down).

[0210] Key results: Initially, the moisture content was extremely high (1845 ppm upright / 1800 ppm inverted). With extended pre-baking time and additional resting periods, the moisture content steadily decreased: from 637 / 691 ppm at 5+(2)+25 to 232 / 177 ppm at 35+(2)+5. The moisture content during inverted baking was consistently slightly lower than that during upright baking. Extending the pre-baking time (e.g., 30+(2)+5, 35+(2)+5) was key to the sustained decrease in moisture content.

[0211] Meaning: The process of baking in stages and then resting can remove moisture more efficiently and is a better process than single-stage baking; inverted baking can further reduce moisture, possibly because gravity reduces the retention of water vapor in the package; extending the pre-baking time is the core means to continuously reduce moisture, and can ultimately control the moisture to a low level of about 200ppm.

[0212] Figure 6 This is a bar chart comparing the moisture content (ppm) of materials under different baking processes. Figure 6 In the diagram, the vertical axis represents moisture content (unit: ppm, parts per million; the lower the value, the better the drying effect). The horizontal axis represents the baking process, formatted as pre-baking time + (resting time) + machine baking time, in hours (h). The total baking time for all processes (excluding resting time) is 30 hours to facilitate comparison of the effects of variables.

[0213] Legend: Blue gradient column: baking upright; Orange column: baking upside down.

[0214] 1. Basic Trends: The Overall Impact of Baking Processes on Moisture Content From left to right, as the proportion of pre-baking time in the process increases and the baking time in the machine decreases, the moisture content of both baking methods shows a continuous downward trend.

[0215] Initial process 0+(0)+30 (no pre-baking, direct baking for 30h): highest moisture content, 1845ppm when upright, 1800ppm when inverted, worst drying effect.

[0216] Final process 35+(2)+5: lowest moisture content, 232ppm when upright and 177ppm when inverted, with the best drying effect.

[0217] Conclusion: Adding a pre-baking step and optimizing the time allocation between pre-baking and machine baking can significantly reduce the moisture content of materials and improve the drying effect.

[0218] 2. Comparison of process and effect of key grouping The diagram uses dashed boxes to divide the process into three stages, each corresponding to a different optimization direction: Characteristics of moisture content changes, representing a key variable in the process stage. Process stage: Basic baking (no pre-baking). Representative process: 0+(0)+30. Core variable: No pre-baking, directly fed into the machine. Characteristics of moisture content change: Moisture content >1800ppm, the difference between the two methods is minimal.

[0219] Process stage: Total baking time 30h (fixed total time). Representative process: 5+(2)+25-20+(2)+10. Core variables: Fixed resting time of 2h, pre-baking from 5h to 20h, and machine entry from 25h to 10h. Characteristics of moisture content change: Moisture content drops rapidly, from ~700ppm to ~400ppm; the moisture content of inverted baking is always slightly higher than that of upright baking (indicating that upright baking has a better drying effect at this stage).

[0220] Process stage: Secondary visual inspection stage. Representative process: 25+(2)+5 / 25+(0)+5. Core variables: Pre-drying for 25 hours, entering the machine for 5 hours, comparing with and without standing. Characteristics of moisture content change: Process with 2 hours of standing: upright 399ppm, inverted 359ppm; Process without standing: upright 395ppm, inverted 284ppm; - The moisture content decreases more significantly when baking inverted without standing.

[0221] Process stage: Extend the pre-baking time. Representative process: 30+(2)+5 / 35+(2)+5. Core variable: Fixed 5h for entering the machine, pre-baking from 30h to 35h. Characteristics of moisture content change: The moisture content continues to decrease, and the advantage of inverted baking becomes prominent: at 35+(2)+5, the moisture content is only 177ppm when inverted, which is much lower than the 232ppm when upright.

[0222] 3. Differences in baking results between upright and inverted baking methods The advantages and disadvantages of the two methods are not fixed, but vary with the stage of the process.

[0223] Early stage (pre-baking ≤20h): Baking with the oven upright results in a lower moisture content and better drying effect than baking with the oven upside down.

[0224] Later stage (pre-drying ≥25h, especially when baking in the machine for only 5h): the moisture content decreases faster when baked upside down, and the final drying effect surpasses that of baking upright.

[0225] Key turning point: After the 25+(0)+5 process, the moisture content of the inverted baking began to be significantly lower than that of the upright baking, indicating that under the process of extending the pre-baking and shortening the pre-baking, the inverted baking is more conducive to the removal of moisture from the material.

[0226] Key findings summary: Process optimization direction: Shifting the focus of baking from direct, long-duration baking to extending pre-baking and shortening the baking time before entering the machine, along with a reasonable settling / no-settling process, is the core approach to reducing moisture content.

[0227] Baking method adaptability: When the pre-baking time is short and the machine baking time is long, upright baking is preferred; when the pre-baking time is sufficient (≥25h) and the machine baking only needs to be finished in a short time, inverted baking can achieve a lower moisture content and better drying effect.

[0228] The effect of resting: In the process of 25h pre-drying + 5h feeding, after the resting step (25+(0)+5) was removed, the moisture content of the inverted baking decreased from 359ppm to 284ppm, indicating that the absence of the resting process is more conducive to the discharge of moisture during inverted baking, while having little effect on upright baking.

[0229] Overall conclusion: A complete optimization logic from materials to processes Materials are fundamental: different materials have vastly different initial moisture content. White film is a material with high moisture risk, while solder / conductive adhesive has even lower initial moisture content.

[0230] Baking is the core process: single-stage baking is inefficient, while two-stage or multi-stage baking combined with resting yields better results. Higher temperatures and longer baking times result in more thorough moisture removal, but the heat resistance of the materials must be considered. Extending pre-baking time and inverting the baking process can further enhance the dehydration effect. Removing the food from the oven at high temperatures after baking can cause it to become damp again, so slow cooling is necessary; adding auxiliary materials such as 9187 can significantly reduce moisture content.

[0231] Ultimate goal: Through material selection and process optimization, reduce moisture content from thousands of ppm to hundreds of ppm, or even below 200 ppm, to meet device reliability requirements.

[0232] Based on the above-mentioned series of core influencing factors, and considering the verification results and actual circumstances, a typical implementation method is determined.

[0233] 1. Baking mode: Two-stage baking.

[0234] 2. Baking temperature: 165℃.

[0235] 3. Baking time: Total baking time is 40 hours.

[0236] 4. Node control: The first stage of baking time is ≥35h, the second stage of baking time is ≥5h, the intermediate dwell time is ≤30min, and the removal temperature is ≤50℃.

[0237] 5. Vacuum environment: The number of vacuum pumping cycles in the first baking process is ≥10t, and the number of vacuum pumping cycles in the second baking process is ≥5t.

[0238] The specific implementation plan can be refined and adjusted according to the product characteristics, equipment capabilities, internal moisture requirements, and other influencing factors, adjusting the parameters of the above six dimensions. This invention uses data to confirm the "moisture return" defect of traditional processes and proposes a complete set of quantitative process combinations including "long-term high-temperature pre-desorption + strict time-limited transfer + low-temperature removal + inverted airflow".

[0239] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products, characterized in that, include: S1. Place the hermetically sealed product to be baked in a vacuum oven and bake it at the preset baking temperature. Vacuum filling and emptying cycles are performed during the baking process. S2. After the first stage of baking is completed, the product is cooled to the preset temperature in the pre-baking vacuum oven and then taken out. After completing the second inspection and applying silicone rubber within the time limit, the product is transferred to the oven provided with the sealing glove box. S3. Use the oven provided with the sealed glove box to perform the second stage of baking at the preset baking temperature, and perform vacuum filling and circulating during the baking process; S4. After the second stage of baking is completed, the equipment is moved directly from the oven on the sealing device to the glove box for sealing.

2. The multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to claim 1, characterized in that, The preset baking temperature is 165℃.

3. The multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to claim 2, characterized in that, The total baking time is 40 hours, of which the first baking time is ≥35 hours and the second baking time is ≥5 hours.

4. The multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to claim 1, characterized in that, In step S2, the predetermined time for the intermediate stop between the first and second baking stages is ≤30 minutes.

5. The multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to claim 1, characterized in that, In step S2, the product temperature after baking is ≤50℃.

6. The multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to claim 1, characterized in that, In step S1, the number of vacuum pumping cycles during the first stage of baking is ≥10; in step S3, the number of vacuum pumping cycles during the second stage of baking is ≥5.

7. The multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to claim 1, characterized in that, Before step S1, the process includes: preparing individual samples of the process auxiliary materials to determine the sensitivity of each type of process auxiliary material to the effects of baking temperature and baking time.

8. The multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to claim 1, characterized in that, Hermetically sealed products are hybrid integrated circuits, semiconductor discrete devices, or microwave and radio frequency components.

9. A multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to claim 1, characterized in that, Hermetically sealed products are hermetically sealed products with a cavity volume ≤ 80cm³, and the internal moisture content after baking is ≤ 2000ppm.

10. A multi-stage vacuum baking method for reducing internal moisture in hermetically sealed products according to any one of claims 1-9, characterized in that, The parameters of six dimensions—baking mode, baking temperature, baking time, node control, vacuum environment, and product placement method—are adjusted according to product characteristics, equipment capacity, and moisture requirements.

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