AMB ceramic substrate and FPC flexible circuit board pressing process

Abstract

The application discloses a kind of AMB ceramic substrate and FPC flexible circuit board's compression process, it is related to the field of semiconductor technology, comprising the following steps: AMB substrate preparation;FPC flexible plate preparation;Pre-compression cleaning;Vacuum compression;Laser cutting shape;Functional coating is coated;The application is through a kind of AMB ceramic substrate and FPC flexible circuit board's compression process, and it is convenient to accurately position that AMB ceramic substrate and FPC flexible circuit board positioning hole position are reserved in design stage, and AMB substrate pre-cleaning process is guaranteed with FPC substrate vacuum hot-pressing bonding force before compression, simultaneously, the filler of coating is handled by long-chain alkyl silane, and the moisture-proof and anti-permeability of coating are significantly improved.The application is by optimizing compression process and functional protective coating, so that packaging structure simultaneously has excellent mechanical reliability, corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically a bonding process between an AMB ceramic substrate and an FPC flexible circuit board. Background Technology

[0002] As high-end power modules, represented by insulated-gate bipolar transistors (IGBTs) and silicon carbide (SiC), evolve towards higher power density, higher reliability, and more compact packaging, the packaging structure combining active metal brazed ceramic substrates and flexible printed circuit boards has become one of the key technological paths. Reliably bonding the flexible circuit board, which carries control signals, sensing, and driving functions, onto the active metal brazed ceramic substrate, which is responsible for high current carrying and efficient heat dissipation, is the core process for achieving electrical interconnection, mechanical fixation, and integrated module functionality.

[0003] Currently, the industry commonly uses conventional thermocompression welding technology to bond flexible circuit boards to active metal brazed ceramic substrates. However, this technology has significant limitations. First, because the active metal brazed ceramic substrate itself is brittle and hard, uneven or excessive pressing pressure in traditional thermocompression welding processes can easily lead to microcracks in the substrate, severely affecting the mechanical reliability and long-term service life of the module. Second, thermal and mechanical stresses during the pressing process can cause misalignment of the pattern and deformation of the circuit, resulting in poor pressing and reduced electrical connection reliability. In addition, if the interface cleanliness is not adequately controlled or the process parameters are not properly matched, voids or weak adhesive layers can be introduced at the bonding interface, resulting in insufficient bonding strength and the risk of delamination, blistering, and other failures under subsequent high temperature, high humidity, or power cycling conditions. Furthermore, care must be taken to avoid pressing the delicate circuitry of the flexible circuit board into the circuit trenches of the ceramic substrate during the pressing process, which could affect current conduction performance.

[0004] To address the aforementioned problems, this invention provides a lamination process for an AMB ceramic substrate and an FPC flexible circuit board. Summary of the Invention

[0005] The purpose of this invention is to provide a lamination process for an AMB ceramic substrate and an FPC flexible circuit board to solve the problems mentioned in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A lamination process for an AMB ceramic substrate and an FPC flexible circuit board includes the following steps: S1: AMB substrate fabrication: AMB substrate is fabricated through sintering, masking, etching, solder resist, surface treatment, and laser marking. S2: FPC flexible board preparation: FPC flexible boards are prepared through material cutting, pattern transfer, etching, attaching cover film, pressing, baking, surface treatment, electrical testing, and punching. S3: Pre-lamination cleaning: Clean the AMB substrate and FPC flexible board separately. S4: Vacuum pressing: Take the AMB substrate and the FPC flexible board and perform vacuum segmented pressing. Heating plates are set at the top and bottom. Pre-pressing, pressing and holding pressure pressing are performed to obtain the pressed substrate. The heating plate is divided into an upper plate and a lower plate. S5: Laser cutting of the shape: The laminated substrate is cut to obtain the finished substrate.

[0007] Furthermore, during pre-pressing, the upper plate temperature is 120-125℃, the lower plate temperature is 100-105℃, the booster pressure is 0.4-0.5MPa, the vacuum is 0.2-0.4pa, and the delay is 5-7s.

[0008] Furthermore, during the pressing process, the upper plate temperature is 140-145℃, the lower plate temperature is 130-135℃, the booster pressure is 0.5-0.7MPa, the vacuum is 0.2-0.4pa, the delay is 10-12s, and the pressure holding time is 90-95s.

[0009] Furthermore, during the pressure-pressing process, the upper plate temperature is 120-125℃, the lower plate temperature is 120-125℃, the booster pressure is 0.5-0.7MPa, the vacuum is 0.2-0.4pa, there is no delay, and the pressure is maintained for 10-12 minutes.

[0010] Furthermore, in S4, conductive films are used for vacuum bonding on both sides. The lower surface of the conductive film is a double-sided non-silicone release film with a thickness of 20-30 μm; the upper surface is a double-sided release film with a thickness of 35-40 μm.

[0011] Furthermore, the surface of the finished substrate is coated with a functional coating. The process is as follows: the functional coating slurry is uniformly coated on the surface of the AMB ceramic substrate laminated FPC flexible circuit board; cured at 50-60℃ for 3-4 hours to obtain the finished AMB ceramic substrate laminated FPC flexible circuit board.

[0012] Furthermore, the functional coating slurry is composed of the following components by mass percentage: 18-20 wt% hydrophobic modified alumina, 15-20 wt% hydrophobic modified carbon fiber, 8-10 wt% curing agent, 0.5-1 wt% defoamer, 0.5-1 wt% leveling agent, and the balance being epoxy branched polyimide resin.

[0013] Furthermore, the preparation method of the hydrophobic modified alumina is as follows: octadecyltrichlorosilane is added to anhydrous ethanol and stirred to prepare hydrophobic treatment solution A; alumina is added to a beaker of anhydrous ethanol, heated to 70-80℃, and stirred for 20-40 minutes to form suspension B; while stirring, hydrophobic treatment solution A is added dropwise to suspension B; after the addition is complete, the mixture is heated to 70℃ and stirred continuously for 3-4 hours; after the reaction is completed, the mixture is cooled, filtered, washed with anhydrous ethanol, dried in a vacuum drying oven at 60℃ for 10 hours, and ground to obtain hydrophobic modified alumina.

[0014] Furthermore, the preparation method of the hydrophobic modified carbon fiber is as follows: take octadecyltrichlorosilane, add it to anhydrous ethanol, stir for 20-30 min to prepare a hydrophobic treatment solution; immerse the carbon fiber in anhydrous ethanol, heat to 70℃, stir for 40-50 min, slowly add the hydrophobic treatment solution dropwise while stirring, maintain a water bath temperature of 70℃, continue stirring and react for 3-4 h, after the reaction is completed, take out the carbon fiber, ultrasonically clean it, and vacuum dry it at 50-80℃ for 10 h to obtain the hydrophobic modified carbon fiber.

[0015] Furthermore, the preparation method of the epoxy branched polyimide resin includes the following steps: Step 1: 1,6-Hexamethylenediamine and trimellitic anhydride were condensed in N,N-dimethylformyl; after the reaction was completed, the mixture was cooled, precipitated in ice water, washed with water, recrystallized and purified, and dried under vacuum to obtain imide dicarboxylic acid; Step 2: Take imide dicarboxylic acid, trimethylolethane, dimethylformamide and p-toluenesulfonic acid, stir and heat for 2-3 hours. After the reaction is completed, remove the solvent by vacuum distillation to obtain hyperbranched polyimide. Step 3: Heat the hyperbranched polyimide and epichlorohydrin under reflux for 6-7 hours, then distill under reduced pressure, cool, add sodium hydroxide solution, and continue the reaction for 6-6.5 hours. After the reaction is completed, separate the contents, wash, dry, filter, and distill under reduced pressure again to obtain epoxy branched polyimide resin.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. At the lamination process level, this invention systematically solves the problems of easy cracking of AMB ceramic substrates, poor pattern alignment accuracy, and insufficient interface bonding force in traditional hot-press welding processes by pre-lamination cleaning, dedicated alignment fixtures, and segmented vacuum hot-pressing procedures. This process ensures a uniform, stable, and damage-free strong bond between the FPC flexible circuit board and the AMB substrate under high temperature and high pressure, significantly improving the yield of the lamination process and the mechanical reliability of the product.

[0017] 2. Regarding long-term environmental reliability, this invention coats the surface of the pressed component with a corrosion-resistant resin coating based on hyperbranched polyimide-based epoxy resin and reinforced with hydrophobically modified fillers. The unique three-dimensional structure and abundant terminal epoxy groups of this hyperbranched resin enable a tighter bond between it and the ceramic and carbon fiber fillers treated with long-chain alkylsilanes. This significantly improves the uniformity of filler dispersion and compatibility within the resin matrix. By introducing alumina and carbon fiber fillers treated with long-chain alkylsilanes, this coating forms a dense chemical hydrophobic barrier at the interface, endowing the packaged component with excellent resistance to water vapor permeation and salt spray corrosion. This allows power module packages prepared using this process to maintain stable electrical insulation performance and structural integrity under high temperature and high humidity environments, greatly extending their service life. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments, and all described quantities are by weight. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The sources and types of substances involved in this invention are not specifically limited. Exemplary examples include the following raw materials: Alumina: particle size: 20µm, available from Shanghai Zhongye New Materials Co., Ltd.; Carbon fiber: particle size: 150µm, available from Fujian Rilian Co., Ltd.; Curing agent: product number: Ancamine2280, available from Shanghai Evonik Specialty Chemicals Co., Ltd.; Defoamer: product number: B458, available from Zhonglianbang Co., Ltd.; Leveling agent: SH-432, available from Hubei Longsheng New Materials Co., Ltd.; Double-sided non-silicone release film: transparent double-sided non-silicone release film, product number: 25C64-LB; Double-sided release film: matte white double-sided release film, product number: 38m266-02, available from Taibo Adhesive Materials (Dongtai) Co., Ltd. Example 1:

[0020] S1: AMB substrate fabrication The substrate is taken, sintered, masked, etched, solder resisted, surface treated, and laser marked to obtain the AMB substrate; S2: FPC Flexible Board Fabrication Take a flexible board, cut it, transfer the pattern, etch it, attach a cover film, press it, bake it, treat the surface, test it, and punch it to form an FPC flexible board. S3: Pre-compression cleaning The pre-compression cleaning process employs segmented cleaning. The AMB substrate undergoes ultrasonic cleaning with ultrapure water, drying, and plasma cleaning to ensure cleanliness. The FPC flexible board undergoes ultrasonic cleaning with ultrapure water, drying, and inductively coupled plasma cleaning to ensure cleanliness. S4: Vacuum pressing The AMB substrate and the FPC flexible board were vacuum-pressed. The vacuum pressing was performed using a vacuum press machine, employing a segmented temperature zone and multiple vacuum-coordinated pressing environment, consisting of three stages: pre-pressing, pressing, and pressure-holding pressing. During pre-pressing, the upper plate temperature was 120℃, the lower plate temperature was 100℃, the booster pressure was 0.4MPa, the vacuum was 0.2pa, and the delay was 5s. During pressing, the upper plate temperature was 140℃, the lower plate temperature was 130℃, the booster pressure was 0.5MPa, the vacuum was 0.2pa, the delay was 10s, and the pressure was held for 90s. During pressure-holding pressing, the upper and lower plate temperatures were both 120℃, the booster pressure was 0.5MPa, the vacuum was 0.2pa, there was no delay, and the pressure was held for 10 minutes. The conductive films on the upper and lower surfaces are vacuum-pressed as follows: the lower film surface is a double-sided non-silicone release film with a thickness of 25μm; the upper film surface is a double-sided release film with a thickness of 38μm. S5: Laser-cut shape The laser cutting shape is cut using ultraviolet nanosecond equipment, cutting through the FPC and simultaneously cutting the AMB substrate to obtain the finished product of AMB ceramic substrate laminated FPC flexible circuit board. Example 2:

[0021] S1: AMB substrate fabrication The substrate is taken, sintered, masked, etched, solder resisted, surface treated, and laser marked to obtain the AMB substrate; S2: FPC Flexible Board Fabrication Take a flexible board, cut it, transfer the pattern, etch it, attach a cover film, press it, bake it, treat the surface, test it, and punch it to form an FPC flexible board. S3: Pre-compression cleaning The pre-compression cleaning process employs segmented cleaning. The AMB substrate undergoes ultrasonic cleaning with ultrapure water, drying, and plasma cleaning to ensure cleanliness. The FPC flexible board undergoes ultrasonic cleaning with ultrapure water, drying, and inductively coupled plasma cleaning to ensure cleanliness. S4: Vacuum pressing The AMB substrate and the FPC flexible board were vacuum-pressed. The vacuum pressing was performed using a vacuum press machine, employing a segmented temperature zone and multiple vacuum-coordinated pressing environment, consisting of three stages: pre-pressing, pressing, and pressure-holding pressing. Pre-pressing: upper plate temperature 122℃, lower plate temperature 102℃, pressurization pressure 0.45MPa, vacuum 0.3pa, delay 6s; pressing plate temperature 142℃, lower plate temperature 132℃, pressurization pressure 0.6MPa, vacuum 0.3pa, delay 12s, pressure holding 92s; pressure-holding pressing: pressing plate temperature 122℃, lower plate temperature 122℃, pressurization pressure 0.6MPa, vacuum 0.3pa, no delay, pressure holding 12min. The conductive films on the upper and lower surfaces are vacuum-pressed as follows: the lower film surface is a double-sided non-silicone release film with a thickness of 26 μm; the upper film surface is a double-sided release film with a thickness of 39 μm. S5: Laser-cut shape The laser cutting shape is cut using ultraviolet nanosecond equipment, cutting through the FPC and simultaneously cutting the AMB substrate to obtain the finished product of AMB ceramic substrate laminated FPC flexible circuit board. Example 3:

[0022] S1: AMB substrate fabrication The substrate is taken, sintered, masked, etched, solder resisted, surface treated, and laser marked to obtain the AMB substrate; S2: FPC Flexible Board Fabrication Take a flexible board, cut it, transfer the pattern, etch it, attach a cover film, press it, bake it, treat the surface, test it, and punch it to form an FPC flexible board. S3: Pre-compression cleaning The pre-compression cleaning process employs segmented cleaning. The AMB substrate undergoes ultrasonic cleaning with ultrapure water, drying, and plasma cleaning to ensure cleanliness. The FPC flexible board undergoes ultrasonic cleaning with ultrapure water, drying, and inductively coupled plasma cleaning to ensure cleanliness. S4: Vacuum pressing The AMB substrate and the FPC flexible board were vacuum-pressed. The vacuum pressing was performed using a vacuum press machine, employing a segmented temperature zone and multiple vacuum-coordinated pressing environment, consisting of three stages: pre-pressing, pressing, and pressure-holding pressing. Pre-pressing: upper plate temperature 125℃, lower plate temperature 105℃, pressurization pressure 0.5MPa, vacuum 0.4pa, delay 7s; pressing plate temperature 145℃, lower plate temperature 135℃, pressurization pressure 0.7MPa, vacuum 0.4pa, delay 12s, pressure holding 95s; pressure-holding pressing: pressing plate temperature 125℃, lower plate temperature 125℃, pressurization pressure 0.7MPa, vacuum 0.4pa, no delay, pressure holding 10min. The conductive films on the upper and lower surfaces are vacuum-pressed as follows: the lower film is a double-sided non-silicone release film with a thickness of 27 μm; the upper film is a double-sided release film with a thickness of 40 μm. S5: Laser-cut shape The laser cutting shape is cut using ultraviolet nanosecond equipment, cutting through the FPC and simultaneously cutting the AMB substrate to obtain the finished product of AMB ceramic substrate laminated FPC flexible circuit board. Example 4:

[0023] S1: AMB substrate fabrication The substrate is taken, sintered, masked, etched, solder resisted, surface treated, and laser marked to obtain the AMB substrate; S2: FPC Flexible Board Fabrication Take a flexible board, cut it, transfer the pattern, etch it, attach a cover film, press it, bake it, treat the surface, test it, and punch it to form an FPC flexible board. S3: Pre-compression cleaning The pre-compression cleaning process employs segmented cleaning. The AMB substrate undergoes ultrasonic cleaning with ultrapure water, drying, and plasma cleaning to ensure cleanliness. The FPC flexible board undergoes ultrasonic cleaning with ultrapure water, drying, and inductively coupled plasma cleaning in a Class 1000 cleanroom to ensure cleanliness. S4: Vacuum pressing The AMB substrate and the FPC flexible board were vacuum-pressed. Vacuum pressing was performed using a vacuum press machine, employing a segmented temperature zone and multiple vacuum-coordinated pressing environment, consisting of three stages: pre-pressing, pressing, and pressure-holding pressing. Pre-pressing: upper plate temperature 120℃, lower plate temperature 100℃, pressurization pressure 0.45MPa, vacuum 0.2pa, delay 5s; pressing plate temperature 140℃, lower plate temperature 130℃, pressurization pressure 0.5MPa, vacuum 0.2pa, delay 10s, pressure holding 90s. This step aims for thorough pressing and good contact between the two phases. Pressure-holding pressing: pressing plate temperature 120℃, lower plate temperature 120℃, pressurization pressure 0.5MPa, vacuum 0.2pa, no delay, pressure holding 10min. The conductive films on the upper and lower surfaces are vacuum-pressed as follows: the lower film surface is a double-sided non-silicone release film with a thickness of 25μm and a release force of 8g / 25mm; the upper film surface is a double-sided release film with a thickness of 38μm and a release force of 12g / 25mm. S5: Laser-cut shape The laser cutting shape is cut using ultraviolet nanosecond equipment, cutting through the FPC and simultaneously cutting the AMB substrate to obtain an AMB ceramic substrate laminated with an FPC flexible circuit board. S6: Apply functional coating Weigh out 3 wt% of alumina particles of octadecyltrichlorosilane, add it to 50 mL of anhydrous ethanol, place it on a magnetic stirrer, and stir at 1000 r / min for 20 min to fully dissolve it, thus preparing hydrophobic treatment solution A. Add 10g of alumina to 50mL of anhydrous ethanol, place it in a water bath, heat to 70℃, and stir at 1000r / min for 30min to fully disperse the alumina particles and form suspension B. Under continuous stirring, the hydrophobic treatment solution A was slowly added dropwise to the suspension B. After the addition was complete, the mixture was heated in a water bath at 70°C and stirred continuously for 3 hours. After the reaction was completed, the mixture was cooled, filtered, washed with anhydrous ethanol, dried in a vacuum drying oven at 60°C for 10 hours, and ground to obtain hydrophobically modified alumina. Weigh out 3 wt% of carbon fiber mass of octadecyltrichlorosilane, add it to 50 mL of anhydrous ethanol, place it on a magnetic stirrer, and stir at 1000 r / min for 20 min to fully dissolve it, thus preparing a hydrophobic treatment solution. 10g of carbon fiber was immersed in a beaker containing an appropriate amount of anhydrous ethanol. The container was placed in a water bath and heated to 70°C. The mixture was stirred at 1200r / min for 40min to ensure that the carbon fiber was fully wetted. While stirring, the hydrophobic treatment solution was slowly added dropwise. The water bath temperature was maintained at 70°C, and the reaction was continued for 3h. After the reaction was completed, the carbon fiber was removed, ultrasonically cleaned with anhydrous ethanol, and vacuum dried at 50-80°C for 10h to obtain hydrophobically modified carbon fiber. 0.116 g of 1,6-hexanediamine and 0.192 g of trimellitic anhydride were condensed in 20 mL of N,N-dimethylformyl for 3 h. After the reaction was completed, the mixture was cooled, precipitated with ice water, washed with water, recrystallized and purified, and dried under vacuum to obtain imide dicarboxylic acid. In a three-necked flask, 0.09 mol of imide dicarboxylic acid, 0.04 mol of trimethylolethane, 30 mL of N,N-dimethylformamide and 0.01 mol of p-toluenesulfonic acid were added. The mixture was stirred and heated for 3 h under nitrogen protection. After the reaction was completed, the solvent was removed by vacuum distillation to obtain hyperbranched polyimide. 0.05 mol hyperbranched polyimide and 0.2 mol epichlorohydrin were heated under reflux for 6 h. Then, the mixture was distilled under reduced pressure, cooled, and 20 mL of 10 wt% sodium hydroxide solution was added in portions. The reaction was continued for another 6 h. After the reaction was completed, the mixture was separated, washed, dried, filtered, and distilled under reduced pressure again to obtain epoxy branched polyimide resin. Take epoxy branched polyimide resin, curing agent, defoamer, leveling agent, hydrophobic modified alumina, and hydrophobic modified carbon fiber. Add the hydrophobic modified alumina and hydrophobic modified carbon fiber sequentially to the epoxy resin, then stir at 1000 r / min for 80 min. Add the leveling agent and defoamer sequentially, then stir at 500 r / min for 30 min. Add the curing agent and stir at 500 r / min for 5 min to obtain a functional coating slurry. The composition of the functional coating slurry, by mass percentage, is: 20 wt% hydrophobic modified alumina, 15 wt% hydrophobic modified carbon fiber, 10 wt% curing agent, 0.5 wt% defoamer, 0.5 wt% leveling agent, with the balance being epoxy branched polyimide resin. The functional coating slurry was uniformly coated onto the surface of the AMB ceramic substrate laminated FPC flexible circuit board at a speed of 200 mm / min; it was cured at 60°C for 3 hours to obtain the finished AMB ceramic substrate laminated FPC flexible circuit board.

[0024] Comparative Example 1: In S4, vacuum segmented pressing was not used; conventional pressing was used instead. The rest was the same as in Example 1.

[0025] Comparative Example 2: The aluminum oxide in the coating was not modified to be hydrophobic, and the rest was the same as in Example 4.

[0026] Comparative Example 3: No epoxy branched polyimide resin was used in the coating; ordinary epoxy resin was used instead. The rest was the same as in Example 4.

[0027] experiment: (1) Mechanical performance test: The AMB ceramic substrate laminated FPC flexible circuit board products prepared in Examples 1-4 and Comparative Examples 1-3 of this invention were subjected to mechanical performance test. The bending strength (MPa) was measured by the three-point bending method and a universal testing machine (Instron5967) with a loading rate of 0.5 mm / min. (2) The corrosion resistance of the AMB ceramic substrate laminated FPC flexible circuit boards prepared in Examples 1-4 and Comparative Examples 1-3 was tested using the international standard ISO9227:2012 with reference to the international standard ISO9227:2012. The time for rust to appear in the salt spray was recorded. The data are shown in Table 1 below:

[0028] Conclusion: The data above shows that the lamination process provided by this invention can prepare AMB ceramic substrate and FPC flexible circuit board assembly with excellent interfacial adhesion. The excellent tensile test results indicate that this process effectively ensures the basic mechanical reliability of the assembly. Furthermore, the assembly laminated and coated with a protective coating based on hyperbranched polyimide epoxy resin using this process exhibits extremely long corrosion resistance time in the neutral salt spray test, demonstrating that this solution provides the packaging structure with excellent long-term environmental stability. In summary, the AMB-FPC packaging assembly prepared by this invention combines high mechanical strength with high environmental reliability.

[0029] Comparative Example 1 did not use the segmented vacuum pressing process of the present invention, but used a conventional pressing method. Compared with Example 1, the tensile strength of the resulting component was significantly reduced, and the salt spray corrosion time was also greatly shortened. This shows that the segmented vacuum pressing process of the present invention is crucial for obtaining a strong interface bond and a reliable product foundation.

[0030] Comparative Example 2 did not perform hydrophobic modification on the alumina filler in the coating. Compared with Example 4, the salt spray corrosion time of the obtained component was significantly reduced, indicating that hydrophobic treatment of alumina is the key to building an effective moisture-proof and corrosion-proof barrier, which can significantly improve the coating's impermeability.

[0031] In Comparative Example 3, a conventional epoxy resin was used in the coating instead of the epoxy-branched polyimide resin of the present invention. Compared with Example 2, the salt spray corrosion time of the resulting component was significantly shortened. This indicates that the interfacial compatibility and bonding strength between the conventional epoxy resin and the hydrophobically modified filler are insufficient. Therefore, the unique branched structure of the epoxy-branched polyimide resin plays a crucial role in achieving efficient filler dispersion, constructing a strong and tough coating matrix, and ultimately achieving excellent comprehensive protective performance.

[0032] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A lamination process for an AMB ceramic substrate and an FPC flexible circuit board, characterized in that: Includes the following steps: S1: AMB substrate fabrication: AMB substrate is fabricated through sintering, masking, etching, solder resist, surface treatment, and laser marking. S2: FPC flexible board preparation: FPC flexible boards are prepared through material cutting, pattern transfer, etching, attaching cover film, pressing, baking, surface treatment, electrical testing, and punching. S3: Pre-lamination cleaning: Clean the AMB substrate and FPC flexible board separately. S4: Vacuum pressing: Take the AMB substrate and the FPC flexible board and perform vacuum segmented pressing. Heating plates are set at the top and bottom. Pre-pressing, pressing and holding pressure pressing are performed to obtain the pressed substrate. The heating plate is divided into an upper plate and a lower plate. S5: Laser cutting of the shape: The laminated substrate is cut to obtain the finished substrate.

2. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 1, characterized in that: During pre-pressing, the upper plate temperature is 120-125℃, the lower plate temperature is 100-105℃, the booster pressure is 0.4-0.5MPa, the vacuum is 0.2-0.4pa, and the delay is 5-7s.

3. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 1, characterized in that: During pressing, the upper plate temperature is 140-145℃, the lower plate temperature is 130-135℃, the booster pressure is 0.5-0.7MPa, the vacuum is 0.2-0.4pa, the delay is 10-12s, and the pressure holding time is 90-95s.

4. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 1, characterized in that: During the pressure holding and pressing process, the upper plate temperature is 120-125℃, the lower plate temperature is 120-125℃, the booster air pressure is 0.5-0.7MPa, the vacuum is 0.2-0.4pa, there is no delay, and the pressure holding time is 10-12min.

5. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 1, characterized in that: In S4, conductive films are used for vacuum bonding on both the upper and lower surfaces. The lower surface of the conductive film is a double-sided non-silicon release film with a thickness of 20-30 μm; the upper surface is a double-sided release film with a thickness of 35-40 μm.

6. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 1, characterized in that: The surface of the finished substrate is coated with a functional coating. The process is as follows: the functional coating slurry is uniformly coated on the surface of the AMB ceramic substrate laminated FPC flexible circuit board; cured at 50-60℃ for 3-4 hours to obtain the finished AMB ceramic substrate laminated FPC flexible circuit board.

7. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 6, characterized in that: The functional coating slurry is composed of the following components by mass percentage: 18-20 wt% hydrophobic modified alumina, 15-20 wt% hydrophobic modified carbon fiber, 8-10 wt% curing agent, 0.5-1 wt% defoamer, 0.5-1 wt% leveling agent, and the balance being epoxy branched polyimide resin.

8. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 7, characterized in that: The method for preparing the hydrophobic modified alumina is as follows: Octadecyltrichlorosilane is added to anhydrous ethanol and stirred to prepare a hydrophobic treatment solution A; alumina is added to a beaker of anhydrous ethanol, heated to 70-80℃, and stirred for 20-40 minutes to form a suspension B; while stirring, hydrophobic treatment solution A is added dropwise to suspension B; after the addition is complete, the mixture is heated to 70℃ and stirred continuously for 3-4 hours; after the reaction is complete, the mixture is cooled, filtered, washed with anhydrous ethanol, dried in a vacuum drying oven at 60℃ for 10 hours, and ground to obtain the hydrophobic modified alumina.

9. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 7, characterized in that: The method for preparing the hydrophobic modified carbon fiber is as follows: take octadecyltrichlorosilane, add it to anhydrous ethanol, stir for 20-30 min to prepare a hydrophobic treatment solution; immerse the carbon fiber in anhydrous ethanol, heat to 70℃, stir for 40-50 min, slowly add the hydrophobic treatment solution dropwise while stirring, maintain a water bath temperature of 70℃, continue stirring and react for 3-4 h, after the reaction is completed, take out the carbon fiber, ultrasonically clean it, and vacuum dry it at 50-80℃ for 10 h to obtain the hydrophobic modified carbon fiber.

10. The lamination process of the AMB ceramic substrate and the FPC flexible circuit board according to claim 7, characterized in that: The preparation method of the epoxy branched polyimide resin includes the following steps: Step 1: 1,6-Hexamethylenediamine and trimellitic anhydride were condensed in N,N-dimethylformyl; after the reaction was completed, the mixture was cooled, precipitated in ice water, washed with water, recrystallized and purified, and dried under vacuum to obtain imide dicarboxylic acid; Step 2: Take imide dicarboxylic acid, trimethylolethane, dimethylformamide and p-toluenesulfonic acid, stir and heat for 2-3 hours. After the reaction is completed, remove the solvent by vacuum distillation to obtain hyperbranched polyimide. Step 3: Heat the hyperbranched polyimide and epichlorohydrin under reflux for 6-7 hours, then distill under reduced pressure, cool, add sodium hydroxide solution, and continue the reaction for 6-6.5 hours. After the reaction is completed, separate the contents, wash, dry, filter, and distill under reduced pressure again to obtain epoxy branched polyimide resin.

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