Anti-static rigid-flex PCB and processing technology thereof

Abstract

The application discloses an anti-static soft and hard combined PCB and a processing technology thereof and belongs to the technical field of PCB preparation. The processing technology of the anti-static soft and hard combined PCB comprises the following steps: step one, preparing polyimide base material particles and epoxy resin base material particles; step two, preparing polyimide copper-clad plates and epoxy resin copper-clad plates; step three, cutting the polyimide copper-clad plates and the epoxy resin copper-clad plates, roughening the surfaces of copper foils, coating photoresists, pre-baking, exposing, developing, etching, removing films, laminating, vacuum pressing, drilling, copper sinking, electroplating, manufacturing outer layer circuits, solder resist, surface treatment, forming, cutting and obtaining the anti-static soft and hard combined PCB. The PCB prepared by the above method has excellent anti-static performance.

Description

Technical Field

[0001] This invention belongs to the field of PCB board manufacturing technology, specifically relating to antistatic rigid-flex PCB boards and their processing technology. Background Technology

[0002] Rigid-flex PCBs, an innovative achievement in the electronics manufacturing industry, deeply integrate the mechanical support of rigid PCBs with the flexibility of flexible PCBs, breaking through the limitations of traditional circuit boards in three-dimensional spatial layout. They are widely used in foldable screen devices, wearable products, and automotive electronics. However, their multi-layered heterogeneous material structure significantly increases the difficulty of electrostatic discharge (ESD) protection. Traditional ESD designs are prone to failure in the transition zone between rigid and flexible materials. Due to the high surface resistivity of flexible materials and the presence of micro-gaps at the interlayer interfaces, static charges accumulate here, leading to breakdown. Simultaneously, under dynamic bending scenarios, the mechanical stress generated by material deformation further damages the ESD protection or the electrical connections of devices, resulting in a decrease in protective performance. This technological bottleneck makes rigid-flex PCBs face a higher risk of ESD damage in precision electronic assembly, necessitating improvements in their ESD performance through material modification, structural optimization, and process innovation.

[0003] Patent CN114727475A discloses a low-impedance antistatic composite PCB circuit board and its manufacturing method, comprising a board body, a second antistatic layer disposed on the top of the board body, the second antistatic layer comprising an epoxy resin coating and an ATO antistatic coating, and a first antistatic layer disposed on the bottom of the board body, the first antistatic layer comprising nickel-plated copper conductive cloth and an RB-048 antistatic coating. This invention provides a first antistatic layer, which provides two layers of antistatic protection for the bottom of the board body, and a second antistatic layer, which provides a first layer of antistatic protection for the top of the board body. Through the combination of these structures, the overall antistatic performance of the PCB circuit board is effectively improved. Although this method significantly improves the electrostatic protection capability of the PCB circuit board, there is still room for improvement in its electrostatic performance in practical applications. This is mainly due to the interface compatibility issues between different antistatic materials—there are differences in micropores or bonding forces between epoxy resin coating and ATO antistatic coating, and between nickel-plated copper conductive cloth and RB-04 coating, which may cause local accumulation of static charge during interlayer transfer. Especially under high-frequency dynamic stress or humid environments, the stability of the protective effect will be further reduced. Summary of the Invention

[0004] The purpose of this invention is to provide an antistatic rigid-flex PCB board and its processing technology, which solves the technical problem of poor antistatic effect of existing PCB boards.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a processing technology for an anti-static rigid-flex PCB board, comprising the following steps:

[0007] Step 1: Mix the composite antistatic agent with polyimide resin particles and epoxy resin particles respectively, and extrude and granulate to obtain polyimide substrate particles and epoxy resin substrate particles.

[0008] Step 2: Melt-cast polyimide substrate particles and epoxy resin substrate particles, and then laminate copper foil on one side to obtain polyimide copper-clad laminate and epoxy resin copper-clad laminate.

[0009] Step 3: Cut the polyimide copper-clad laminate and epoxy resin copper-clad laminate into blanks, roughen the surface of the copper foil, coat with photoresist, pre-bake, expose, develop, etch, remove film, stack, vacuum press, drill, deposit copper, electroplat, make outer layer circuits, apply solder mask, surface treat, shape, cut, and obtain an antistatic rigid-flex PCB board.

[0010] Preferably, the preparation method of the composite antistatic agent includes the following steps:

[0011] Q1: Add 5,6-dibromo-1,2-dihydroacenaphthene to a container containing acetic anhydride, stir and heat, then add chromium trioxide, continue heating and stirring, then add to a container containing crushed ice, slowly add concentrated hydrochloric acid, filter under reduced pressure, wash, dry, recrystallize to obtain yellow substance 1.

[0012] Q2: Under argon atmosphere, yellow substance 1, thiaanthra-1-boric acid, tetra(triphenylphosphine)palladium and tetrahydrofuran were added to a container in sequence. After heating and stirring, sodium carbonate aqueous solution was added. After heating and reacting, the mixture was cooled, extracted, dried, concentrated and evaporated to dryness, and purified to obtain dark red solid 2.

[0013] Q3: Add the dark red solid 2, diaminomaleonitrile and acetic acid to the container in sequence, heat and stir under reflux, cool, pour into distilled water, filter under reduced pressure, wash, dry, purify, reflux in ethanol, filter, dry, and obtain the purplish-black solid 3.

[0014] Q4: Mix the purplish-black solid 3 with an aqueous sodium hydroxide solution, heat and stir under reflux, cool, extract, adjust the pH, extract again, combine the organic phases, wash, dry, filter, rotary evaporate, and recrystallize to obtain the composite antistatic agent.

[0015] The synthesis reaction formula for the composite antistatic agent in the above process is as follows:

[0016]

[0017] The mass spectrometry analysis results of yellow substance 1 were: m / z: 339.86 (100.0%), 337.86 (51.1%), 341.85 (48.3%), 340.86 (13.0%), 338.86 (6.7%), 342.86 (6.4%), 341.86 (1.2%); the mass spectrometry analysis results of dark red solid 2 were: m / z: 610.02 (100.0%), 611.02 (42.2%), 612.01 (18.1%), 612.03 (7.5%), 613.02 (7.1%), 612.02 (1.7%), 614.02 (1.6%), 613.03 (1.3%), 614.01 (1.3%); The mass spectrometry analysis results of the purplish-black solid 3 are: m / z: 682.04 (100.0%), 683.04 (47.9%), 684.04 (20.2%), 684.05 (9.2%), 685.04 (8.3%), 686.04 (2.0%), 685.05 (1.7%), 686.03 (1.2%); The mass spectrometry analysis results of the composite antistatic agent are: m / z: 720.03 (100.0%), 721.03 (47.4%), 722.03 (20.7%), 722.04 (9.3%), 723.03 (8.5%), 724.03 (2.1%), 723.04 (1.9%), 724.02 (1.2%).

[0018] Preferably, in Q1, the ratio of 5,6-dibromo-1,2-dihydroacenaphthene, acetic anhydride, chromium trioxide, and concentrated hydrochloric acid is (8.12-9.23) g : (380-430) mL : (21.12-23.36) g : (18-22) mL. The mixture is stirred and heated to 110-115°C, then further heated to 160-164°C and stirred for 30-45 min. The mixture is then washed with distilled water and recrystallized with chlorobenzene.

[0019] Preferably, in Q2, the ratio of yellow substance 1, thiazolyl-1-boric acid, tetra(triphenylphosphine)palladium, tetrahydrofuran, and sodium carbonate aqueous solution is (1.38-2.06) g : (3.12-3.68) g : (0.41-0.53) g : (110-130) mL : (28-32) mL. The mixture is heated to 48-52℃ and stirred for 10-14 min. The concentration of the sodium carbonate aqueous solution is 2 mol / L. The mixture is heated to 65-68℃ and reacted for 10-12 h. The mixture is then extracted with dichloromethane and distilled water, dried with anhydrous sodium sulfate, and separated and purified on a silica gel column using a 3:1 volume ratio of dichloromethane and petroleum ether as eluent.

[0020] Preferably, in Q3, the ratio of dark red solid 2, diaminomaleitrile, and acetic acid is (1.66-1.84) g: (0.21-0.36) g: (45-55) mL. The mixture is heated to 120-125℃ and refluxed with stirring for 20-24 h. It is then washed with distilled water and separated and purified on a silica gel column using dichloromethane and petroleum ether in a volume ratio of 1:1 as eluents.

[0021] Preferably, in Q4, the ratio of the amount of the purplish-black solid 3 to the sodium hydroxide aqueous solution is (2.12-2.38) g: (60-68) mL. The mixture is heated to 100-110℃ and stirred under reflux for 1-3 h. It is then extracted with diethyl ether, the pH is adjusted to 1-2 with 1 mol / L hydrochloric acid, extracted with dichloromethane, and washed with distilled water.

[0022] Preferably, the photoresist is composed of 40-60 parts phenolic epoxy acrylate resin, 3-8 parts photosensitizer, 1-3 parts phthalocyanine blue, 20-40 parts diethylene glycol methyl ethyl ether, and 5-10 parts talc, wherein the preparation method of the photosensitizer includes the following steps:

[0023] S1: 2-hydroxy-5-methoxybenzaldehyde, ethyl acetoacetate and piperidine were added to a container containing anhydrous ethanol and reacted in an ice bath under nitrogen atmosphere. The mixture was then poured into deionized water for recrystallization and filtered to obtain a pale yellow solid a.

[0024] S2: Add the pale yellow solid a to chloroform, then add chloroform containing liquid bromine dropwise. After stirring in an ice bath, distill under reduced pressure, wash, and recrystallize to obtain solid b.

[0025] S3: Add solid b, dimethyl sulfide, and silver hexafluoroantimonate to acetonitrile, stir at room temperature, filter, wash, purify and separate to obtain the photosensitizer.

[0026] The synthesis reaction formula for the photosensitizer in the above process is as follows:

[0027]

[0028] The mass spectrometry analysis results of the pale yellow solid a were: m / z: 218.06 (100.0%), 219.06 (13.2%), 220.06 (1.6%); the mass spectrometry analysis results of solid b were: m / z: 295.97 (100.0%), 297.97 (98.1%), 296.97 (13.2%), 298.97 (12.9%), 299.97 (1.6%); the mass spectrometry analysis results of the photosensitizer were: m / z: 513.96 (100.0%), 515.96 (79.3%), 514.97 (15.5%), 516.97 (11.8%), 517.96 (3.4%), 515.97 (2.1%), 517.97. (1.6%), 516.96 (1.3%).

[0029] Preferably, in step S1, the ratio of 2-hydroxy-5-methoxybenzaldehyde, ethyl acetoacetate, piperidine, and anhydrous ethanol is (1.88-2.21) mL : (2.95-3.12) mL : (0.32-0.38) mL : (55-65) mL, the reaction temperature is 0-1℃, and the reaction time is 4-6 h; in step S2, the ratio of pale yellow solid a to liquid bromine is (1.82-1.95) mL. 5) g: (0.43-0.62) mL, stirring in an ice bath for 3-5 h, washing with diethyl ether, and recrystallizing with acetic acid; in S3, the ratio of solid b, dimethyl sulfide, silver hexafluoroantimonate and acetonitrile is (0.88-1.21) g: (0.21-0.32) mL: (1.21-1.33) g: (55-65) mL, and washing with petroleum ether and diethyl ether in a volume ratio of 1:1.

[0030] Preferably, in step one, the mixing time is 15-30 min, the extrusion temperature of the polyimide resin particles is 280-300℃, and the extrusion temperature of the epoxy resin particles is 160-190℃; in step two, the lamination temperature is 180-210℃, and the pressure is 10-20 MPa; in step three, surface roughening is performed using 100 mL of 150-200 g / L sodium persulfate and 2-3 mL of concentrated sulfuric acid at a temperature of 30-36℃ for 1-2 min to a depth of 1-2 μm, the photoresist coating thickness is 8-12 μm, the pre-baking temperature is 75-85℃ for 15-25 min, and the exposure energy is 150-250 mJ / cm². 2A 1wt% sodium carbonate solution was used as the developer for development at a temperature of 28-32℃. During the lamination process, an epoxy resin prepreg was used as the bonding sheet. Vacuum pressing was performed using a stepped heating method with a vacuum degree of -0.08 to -0.1 MPa. The temperature was increased from room temperature to 130℃ and held for 5 minutes, then increased to 160℃ and held for 7 minutes, then increased to 200℃ and held for 10 minutes, and finally increased to 210℃ and held for 60 minutes.

[0031] As a preferred option, the anti-static rigid-flex PCB board is prepared using the above-mentioned processing technology.

[0032] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0033] 1. The present invention adds the prepared composite antistatic agent and photosensitive agent to the PCB board preparation process, which can not only improve its antistatic performance, but also improve the integrity of the circuit and its anti-etching ability.

[0034] 2. The composite antistatic agent obtained in this invention is added to the PCB board preparation process, which can effectively improve its antistatic performance. The polar and non-polar blocks contained in the composite antistatic agent retain a certain migration ability and can form a three-dimensional conductive network inside the material. The conjugated structure contained in the molecular structure itself has intrinsic conductivity and can directly conduct charges through the "jumping" of electrons in the conjugated system, rather than relying solely on the adsorption of water molecules. Therefore, the presence of the composite antistatic agent can significantly and persistently reduce the surface resistance of the PCB board and transfer the static charge generated during friction or processing in a timely manner, thereby avoiding the risk of electrostatic adsorption of dust, interference with precision circuits, or discharge breakdown. At the same time, it overcomes the defects of traditional small molecule antistatic agents that cause a decrease or failure in surface printing performance due to migration.

[0035] 3. This invention adds the prepared photosensitizer to the PCB board manufacturing process, which can significantly improve the resolution and adhesion of the circuit diagram, thereby meeting the requirements of high-precision circuit manufacturing. The highly photosensitive complex contained in the photosensitizer not only improves its absorption efficiency for specific wavelengths of light, but also generates highly reactive active species during exposure, promoting the rapid curing of the photosensitive layer into a network structure with excellent chemical resistance. This high cross-linking density structure can accurately distinguish between exposed and non-exposed areas during development, achieving high resolution. At the same time, it forms a strong chemical bond with the copper foil substrate, effectively avoiding common problems in traditional processes such as plating penetration and circuit warping, ensuring the integrity of fine circuits and etching resistance. Detailed Implementation

[0036] 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, and not all embodiments. 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.

[0037] Example 1: This example discloses a method for preparing a composite antistatic agent, including the following steps:

[0038] Q1: Add 8.63g of 5,6-dibromo-1,2-dihydroacenaphthene to a container containing 400mL of acetic anhydride, stir and heat to 110℃, then add 22.25g of chromium trioxide, continue heating to 160℃ and stirring for 30min, then add to a container containing crushed ice, slowly add 20mL of concentrated hydrochloric acid, filter under reduced pressure, wash with distilled water, dry, recrystallize with chlorobenzene to obtain yellow substance 1;

[0039] Q2: Under argon atmosphere, 1.62g of yellow substance 1, 3.37g of thiaanthracene-1-boric acid, 0.46g of tetra(triphenylphosphine)palladium and 120mL of tetrahydrofuran were added to a container in sequence. After heating to 50℃ and stirring for 10min, 30mL of sodium carbonate aqueous solution with a concentration of 2mol / L was added. After heating to 65℃ and reacting for 10h, the mixture was cooled and extracted with dichloromethane and distilled water. The organic phase was dried with dichloromethane and distilled water, concentrated and evaporated to dryness. The mixture was separated and purified on a silica gel column using dichloromethane and petroleum ether with a volume ratio of 3:1 as eluent to obtain dark red solid 2.

[0040] Q3: 1.75g ​​of dark red solid 2, 0.28g of diaminomaleonitrile and 50mL of acetic acid were added to a container in sequence. The mixture was heated to 120℃ and stirred under reflux for 24h. After cooling, the mixture was poured into distilled water, filtered under reduced pressure, washed with distilled water, dried, and separated and purified on a silica gel column using dichloromethane and petroleum ether in a volume ratio of 1:1 as eluents. The mixture was then refluxed in ethanol, filtered, dried, and the resulting purplish-black solid 3 was obtained.

[0041] Q4: Mix 2.2g of purplish-black solid 3 with 64mL of 1g / mL sodium hydroxide aqueous solution, heat to 100℃ and stir under reflux for 2h, cool, extract with diethyl ether, adjust pH to 1 with 1mol / L hydrochloric acid, extract with dichloromethane, combine the organic phases, wash with distilled water, dry, filter, rotary evaporate, recrystallize to obtain the composite antistatic agent.

[0042] This embodiment discloses a method for preparing a photosensitizer, including the following steps:

[0043] S1: 2.03 mL of 2-hydroxy-5-methoxybenzaldehyde, 3.01 mL of ethyl acetoacetate and 0.35 mL of piperidine were added to a container containing 60 mL of anhydrous ethanol. The mixture was reacted in an ice bath at 0 °C for 6 h under nitrogen atmosphere. The mixture was then poured into deionized water for recrystallization and filtered to obtain a pale yellow solid a.

[0044] S2: Add 1.87g of pale yellow solid a to 20mL of chloroform, then add dropwise 8mL of chloroform containing 0.53mL of liquid bromine, stir in an ice bath for 4h, distill under reduced pressure, wash with diethyl ether, recrystallize with acetic acid to obtain solid b;

[0045] S3: Add 1.03g solid b, 0.28mL dimethyl sulfide, and 1.28g silver hexafluoroantimonate to 60mL acetonitrile, stir at room temperature, filter, wash with petroleum ether and diethyl ether in a volume ratio of 1:1, purify and separate to obtain the photosensitizer.

[0046] This embodiment discloses a processing technology for an anti-static rigid-flex PCB board, including the following steps:

[0047] Step 1: Mix the composite antistatic agent with polyimide resin particles and epoxy resin particles respectively for 15 minutes, then extrude and granulate. The extrusion temperature of the polyimide resin particles is 300℃, and the extrusion temperature of the epoxy resin particles is 180℃, to obtain polyimide substrate particles and epoxy resin substrate particles.

[0048] Step 2: Melt casting of polyimide substrate particles and epoxy resin substrate particles, and single-sided copper foil lamination, with a lamination temperature of 190℃ and a pressure of 15MPa, to obtain polyimide copper clad laminate and epoxy resin copper clad laminate.

[0049] Step 3: Cut the polyimide copper-clad laminate and epoxy resin copper-clad laminate into blanks. Roughen the surface of the copper foil using 100 mL of 180 g / L sodium persulfate and 2.5 mL of concentrated sulfuric acid at 33°C for 2 min to a depth of 1 μm. Coat the surface with a photoresist (composed of 50 parts phenolic epoxy acrylate resin, 5.5 parts photosensitive agent, 2 parts phthalocyanine blue, 30 parts diethylene glycol methyl ethyl ether, and 7.5 parts talc) to a thickness of 10 μm. Pre-bake at 85°C for 20 min, then expose at an exposure energy of 180 mJ / cm². 2The process involves developing the PCB using a 1wt% sodium carbonate solution at 30℃, followed by etching, film removal, lamination (using epoxy resin prepreg as a bonding sheet), vacuum pressing, and a stepped heating process with a vacuum of -0.1MPa. The PCB is heated from room temperature to 130℃ and held for 5 minutes, then to 160℃ and held for 7 minutes, followed by 200℃ and held for 10 minutes, and finally to 210℃ and held for 60 minutes. The process includes drilling, copper plating, electroplating, fabrication of the outer layer circuitry, solder mask application, surface treatment, shaping, and cutting to obtain an antistatic rigid-flex PCB.

[0050] Example 2: This example discloses a method for preparing a composite antistatic agent, including the following steps:

[0051] Q1: Add 8.12g of 5,6-dibromo-1,2-dihydroacenaphthene to a container containing 380mL of acetic anhydride, stir and heat to 110℃, then add 21.12g of chromium trioxide, continue heating to 160℃ and stirring for 30min, then add to a container containing crushed ice, slowly add 18mL of concentrated hydrochloric acid, filter under reduced pressure, wash with distilled water, dry, recrystallize with chlorobenzene to obtain yellow substance 1;

[0052] Q2: Under argon atmosphere, 1.38 g of yellow substance 1, 3.12 g of thiaanthracene-1-boric acid, 0.41 g of tetra(triphenylphosphine)palladium and 130 mL of tetrahydrofuran were added to a container in sequence. After heating to 50 °C and stirring for 10 min, 28 mL of sodium carbonate aqueous solution with a concentration of 2 mol / L was added. After heating to 65 °C and reacting for 10 h, the mixture was cooled and extracted with dichloromethane and distilled water. The organic phase was dried with dichloromethane and distilled water, concentrated and evaporated to dryness. The mixture was separated and purified on a silica gel column using dichloromethane and petroleum ether with a volume ratio of 3:1 as the eluent to obtain dark red solid 2.

[0053] Q3: 1.66g of dark red solid 2, 0.21g of diaminomaleonitrile and 45mL of acetic acid were added sequentially to a container. The mixture was heated to 120℃ and stirred under reflux for 24h. After cooling, the mixture was poured into distilled water, filtered under reduced pressure, washed with distilled water, dried, and separated and purified on a silica gel column using dichloromethane and petroleum ether in a volume ratio of 1:1 as eluents. The mixture was then refluxed in ethanol, filtered, dried, and the resulting purplish-black solid 3 was obtained.

[0054] Q4: Mix 2.12g of purplish-black solid 3 with 68mL of 1g / mL sodium hydroxide aqueous solution, heat to 100℃ and stir under reflux for 2h, cool, extract with diethyl ether, adjust pH to 1 with 1mol / L hydrochloric acid, extract with dichloromethane, combine the organic phases, wash with distilled water, dry, filter, rotary evaporate, recrystallize to obtain the composite antistatic agent.

[0055] This embodiment discloses a method for preparing a photosensitizer, including the following steps:

[0056] S1: 1.88 mL of 2-hydroxy-5-methoxybenzaldehyde, 2.95 mL of ethyl acetoacetate and 0.32 mL of piperidine were added to a container containing 65 mL of anhydrous ethanol. The mixture was reacted in an ice bath at 0 °C for 6 h under nitrogen atmosphere. The mixture was then poured into deionized water for recrystallization and filtered to obtain a pale yellow solid a.

[0057] S2: Add 1.82g of pale yellow solid a to 20mL of chloroform, then add 8mL of chloroform containing 0.43mL of liquid bromine dropwise. Stir in an ice bath for 4h, then distill under reduced pressure, wash with diethyl ether, and recrystallize with acetic acid to obtain solid b.

[0058] S3: Add 0.88g solid b, 0.21mL dimethyl sulfide, and 1.21g silver hexafluoroantimonate to 55mL acetonitrile, stir at room temperature, filter, wash with petroleum ether and diethyl ether in a volume ratio of 1:1, purify and separate to obtain the photosensitizer.

[0059] This embodiment discloses a processing technology for an anti-static rigid-flex PCB board, including the following steps:

[0060] Step 1: Mix the composite antistatic agent with polyimide resin particles and epoxy resin particles respectively for 15 minutes, then extrude and granulate. The extrusion temperature of the polyimide resin particles is 300℃, and the extrusion temperature of the epoxy resin particles is 180℃, to obtain polyimide substrate particles and epoxy resin substrate particles.

[0061] Step 2: Melt casting of polyimide substrate particles and epoxy resin substrate particles, and single-sided copper foil lamination, with a lamination temperature of 190℃ and a pressure of 15MPa, to obtain polyimide copper clad laminate and epoxy resin copper clad laminate.

[0062] Step 3: Cut the polyimide copper-clad laminate and epoxy resin copper-clad laminate into blanks. Roughen the surface of the copper foil using 100 mL of 180 g / L sodium persulfate and 2.5 mL of concentrated sulfuric acid at 33°C for 2 min to a depth of 1 μm. Coat the surface with a photoresist (composed of 40 parts phenolic epoxy acrylate resin, 8 parts photosensitive agent, 1 part phthalocyanine blue, 40 parts diethylene glycol methyl ethyl ether, and 10 parts talc) to a thickness of 10 μm. Pre-bake at 85°C for 20 min, then expose at an exposure energy of 180 mJ / cm². 2The process involves developing the PCB using a 1wt% sodium carbonate solution at 30℃, followed by etching, film removal, lamination (using epoxy resin prepreg as a bonding sheet), vacuum pressing, and a stepped heating process with a vacuum of -0.1MPa. The PCB is heated from room temperature to 130℃ and held for 5 minutes, then to 160℃ and held for 7 minutes, followed by 200℃ and held for 10 minutes, and finally to 210℃ and held for 60 minutes. The process includes drilling, copper plating, electroplating, fabrication of the outer layer circuitry, solder mask application, surface treatment, shaping, and cutting to obtain an antistatic rigid-flex PCB.

[0063] Example 3: This example discloses a method for preparing a composite antistatic agent, including the following steps:

[0064] Q1: Add 9.23g of 5,6-dibromo-1,2-dihydroacenaphthene to a container containing 430mL of acetic anhydride, stir and heat to 110℃, then add 23.36g of chromium trioxide, continue heating to 160℃ and stirring for 30min, then add to a container containing crushed ice, slowly add 22mL of concentrated hydrochloric acid, filter under reduced pressure, wash with distilled water, dry, recrystallize with chlorobenzene to obtain yellow substance 1;

[0065] Q2: Under argon atmosphere, 2.06 g of yellow substance 1, 3.68 g of thiaanthracene-1-boric acid, 0.53 g of tetra(triphenylphosphine)palladium and 110 mL of tetrahydrofuran were added to a container in sequence. After heating to 50 °C and stirring for 10 min, 32 mL of sodium carbonate aqueous solution with a concentration of 2 mol / L was added. After heating to 65 °C and reacting for 10 h, the mixture was cooled and extracted with dichloromethane and distilled water. The organic phase was dried with dichloromethane and distilled water, concentrated and evaporated to dryness. The mixture was separated and purified on a silica gel column using dichloromethane and petroleum ether with a volume ratio of 3:1 as the eluent to obtain dark red solid 2.

[0066] Q3: 1.84g of dark red solid 2, 0.36g of diaminomaleonitrile and 55mL of acetic acid were added to a container in sequence. The mixture was heated to 120℃ and stirred under reflux for 24h. After cooling, the mixture was poured into distilled water, filtered under reduced pressure, washed with distilled water, dried, and separated and purified on a silica gel column using dichloromethane and petroleum ether in a volume ratio of 1:1 as eluents. The mixture was then refluxed in ethanol, filtered, dried, and the resulting purplish-black solid 3 was obtained.

[0067] Q4: Mix 2.38g of purplish-black solid 3 with 60mL of 1g / mL sodium hydroxide aqueous solution, heat to 100℃ and stir under reflux for 2h, cool, extract with diethyl ether, adjust pH to 1 with 1mol / L hydrochloric acid, extract with dichloromethane, combine the organic phases, wash with distilled water, dry, filter, rotary evaporate, recrystallize to obtain the composite antistatic agent.

[0068] This embodiment discloses a method for preparing a photosensitizer, including the following steps:

[0069] S1: 2.21 mL of 2-hydroxy-5-methoxybenzaldehyde, 3.12 mL of ethyl acetoacetate and 0.38 mL of piperidine were added to a container containing 55 mL of anhydrous ethanol. The mixture was reacted in an ice bath at 0 °C for 6 h under nitrogen atmosphere. Then it was poured into deionized water for recrystallization and filtered to obtain a pale yellow solid a.

[0070] S2: Add 1.95g of pale yellow solid a to 20mL of chloroform, then add 8mL of chloroform containing 0.62mL of liquid bromine dropwise. Stir in an ice bath for 4h, then distill under reduced pressure, wash with diethyl ether, and recrystallize with acetic acid to obtain solid b.

[0071] S3: Add 1.21g of solid b, 0.32mL of dimethyl sulfide, and 1.33g of silver hexafluoroantimonate to 65mL of acetonitrile. Stir at room temperature, filter, and wash with petroleum ether and diethyl ether in a volume ratio of 1:1 to purify and separate the photosensitive agent.

[0072] This embodiment discloses a processing technology for an anti-static rigid-flex PCB board, including the following steps:

[0073] Step 1: Mix the composite antistatic agent with polyimide resin particles and epoxy resin particles respectively for 15 minutes, then extrude and granulate. The extrusion temperature of the polyimide resin particles is 300℃, and the extrusion temperature of the epoxy resin particles is 180℃, to obtain polyimide substrate particles and epoxy resin substrate particles.

[0074] Step 2: Melt casting of polyimide substrate particles and epoxy resin substrate particles, and single-sided copper foil lamination, with a lamination temperature of 190℃ and a pressure of 15MPa, to obtain polyimide copper clad laminate and epoxy resin copper clad laminate.

[0075] Step 3: Cut the polyimide copper-clad laminate and epoxy resin copper-clad laminate into blanks. Roughen the surface of the copper foil using 100 mL of 180 g / L sodium persulfate and 2.5 mL of concentrated sulfuric acid at 33°C for 2 min to a depth of 1 μm. Coat the surface with a photoresist (composed of 60 parts phenolic epoxy acrylate resin, 3 parts photosensitive agent, 3 parts phthalocyanine blue, 20 parts diethylene glycol methyl ethyl ether, and 5 parts talc) to a thickness of 10 μm. Pre-bake at 85°C for 20 min, then expose at an exposure energy of 180 mJ / cm². 2The process involves developing the PCB using a 1wt% sodium carbonate solution at 30℃, followed by etching, film removal, lamination (using epoxy resin prepreg as a bonding sheet), vacuum pressing, and a stepped heating process with a vacuum of -0.1MPa. The PCB is heated from room temperature to 130℃ and held for 5 minutes, then to 160℃ and held for 7 minutes, followed by 200℃ and held for 10 minutes, and finally to 210℃ and held for 60 minutes. The process includes drilling, copper plating, electroplating, fabrication of the outer layer circuitry, solder mask application, surface treatment, shaping, and cutting to obtain an antistatic rigid-flex PCB.

[0076] Example 4: This example discloses a method for preparing a composite antistatic agent, including the following steps:

[0077] Q1: Add 8.37g of 5,6-dibromo-1,2-dihydroacenaphthene to a container containing 390mL of acetic anhydride, stir and heat to 110℃, then add 21.87g of chromium trioxide, continue heating to 160℃ and stirring for 30min, then add to a container containing crushed ice, slowly add 19mL of concentrated hydrochloric acid, filter under reduced pressure, wash with distilled water, dry, recrystallize with chlorobenzene to obtain yellow substance 1;

[0078] Q2: Under argon atmosphere, 1.58 g of yellow substance 1, 3.22 g of thiaanthracene-1-boric acid, 0.44 g of tetra(triphenylphosphine)palladium and 125 mL of tetrahydrofuran were added to a container in sequence. After heating to 50 °C and stirring for 10 min, 31 mL of sodium carbonate aqueous solution with a concentration of 2 mol / L was added. After heating to 65 °C and reacting for 10 h, the mixture was cooled and extracted with dichloromethane and distilled water. The organic phase was dried with dichloromethane and distilled water, concentrated and evaporated to dryness. The mixture was separated and purified on a silica gel column using dichloromethane and petroleum ether with a volume ratio of 3:1 as eluent to obtain dark red solid 2.

[0079] Q3: 1.81g of dark red solid 2, 0.24g of diaminomaleonitrile and 48mL of acetic acid were added to a container in sequence. The mixture was heated to 120℃ and stirred under reflux for 24h. After cooling, the mixture was poured into distilled water, filtered under reduced pressure, washed with distilled water, dried, and separated and purified on a silica gel column using dichloromethane and petroleum ether in a volume ratio of 1:1 as eluents. The mixture was then refluxed in ethanol, filtered, dried, and the resulting purplish-black solid 3 was obtained.

[0080] Q4: Mix 2.16g of purplish-black solid 3 with 62mL of 1g / mL sodium hydroxide aqueous solution, heat to 100℃ and stir under reflux for 2h, cool, extract with diethyl ether, adjust pH to 1 with 1mol / L hydrochloric acid, extract with dichloromethane, combine the organic phases, wash with distilled water, dry, filter, rotary evaporate, recrystallize to obtain the composite antistatic agent.

[0081] This embodiment discloses a method for preparing a photosensitizer, including the following steps:

[0082] S1: 1.96 mL of 2-hydroxy-5-methoxybenzaldehyde, 2.98 mL of ethyl acetoacetate and 0.34 mL of piperidine were added to a container containing 58 mL of anhydrous ethanol. The mixture was reacted in an ice bath at 0 °C for 6 h under nitrogen atmosphere. The mixture was then poured into deionized water for recrystallization and filtered to obtain a pale yellow solid a.

[0083] S2: Add 1.84g of pale yellow solid a to 20mL of chloroform, then add dropwise 8mL of chloroform containing 0.48mL of liquid bromine, stir in an ice bath for 4h, distill under reduced pressure, wash with diethyl ether, recrystallize with acetic acid to obtain solid b;

[0084] S3: Add 0.96g solid b, 0.24mL dimethyl sulfide, and 1.25g silver hexafluoroantimonate to 58mL acetonitrile, stir at room temperature, filter, wash with petroleum ether and diethyl ether in a volume ratio of 1:1, purify and separate to obtain the photosensitizer.

[0085] This embodiment discloses a processing technology for an anti-static rigid-flex PCB board, including the following steps:

[0086] Step 1: Mix the composite antistatic agent with polyimide resin particles and epoxy resin particles respectively for 15 minutes, then extrude and granulate. The extrusion temperature of the polyimide resin particles is 300℃, and the extrusion temperature of the epoxy resin particles is 180℃, to obtain polyimide substrate particles and epoxy resin substrate particles.

[0087] Step 2: Melt casting of polyimide substrate particles and epoxy resin substrate particles, and single-sided copper foil lamination, with a lamination temperature of 190℃ and a pressure of 15MPa, to obtain polyimide copper clad laminate and epoxy resin copper clad laminate.

[0088] Step 3: Cut the polyimide copper-clad laminate and epoxy resin copper-clad laminate into blanks. Roughen the surface of the copper foil using 100 mL of 180 g / L sodium persulfate and 2.5 mL of concentrated sulfuric acid at 33°C for 2 min to a depth of 1 μm. Coat the surface with a photoresist (composed of 45 parts phenolic epoxy acrylate resin, 4 parts photosensitive agent, 1.5 parts phthalocyanine blue, 28 parts diethylene glycol methyl ethyl ether, and 8 parts talc) to a thickness of 10 μm. Pre-bake at 85°C for 20 min, then expose at an exposure energy of 180 mJ / cm². 2The process involves developing the PCB using a 1wt% sodium carbonate solution at 30℃, followed by etching, film removal, lamination (using epoxy resin prepreg as a bonding sheet), vacuum pressing, and a stepped heating process with a vacuum of -0.1MPa. The PCB is heated from room temperature to 130℃ and held for 5 minutes, then to 160℃ and held for 7 minutes, followed by 200℃ and held for 10 minutes, and finally to 210℃ and held for 60 minutes. The process includes drilling, copper plating, electroplating, fabrication of the outer layer circuitry, solder mask application, surface treatment, shaping, and cutting to obtain an antistatic rigid-flex PCB.

[0089] Comparative Example 1: Compared with Example 1, Comparative Example 1 did not add composite antistatic agent during the preparation of antistatic rigid-flex PCB board, and all other conditions remained unchanged.

[0090] Comparative Example 2: Compared with Example 1, Comparative Example 2 did not add photosensitizer during the preparation of the antistatic rigid-flex PCB board, and all other conditions remained unchanged.

[0091] Performance testing:

[0092] The antistatic rigid-flex PCBs prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to performance tests. The antistatic properties of the samples were tested according to GB / T 31838.2-2019, and the etching resistance of the samples was tested according to GB / T 29846-2025. The test results are shown in Table 1.

[0093] Table 1

[0094]

[0095] As shown in Table 1, the test results indicate that PCB boards with excellent antistatic properties and excellent etching resistance can be prepared by using the methods of Examples 1-4. A comparison between Comparative Example 1 and Examples 1-4 reveals that the use of a composite antistatic agent can effectively improve the antistatic properties of the PCB board; a comparison between Comparative Example 2 and Examples 1-4 reveals that the use of a photosensitizer can effectively improve the etching resistance of the PCB board.

[0096] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0097] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. The processing technology of antistatic rigid-flex PCB board, characterized in that, Includes the following steps: Step 1: Mix the composite antistatic agent with polyimide resin particles and epoxy resin particles respectively, and extrude and granulate to obtain polyimide substrate particles and epoxy resin substrate particles. Step 2: Melt-cast polyimide substrate particles and epoxy resin substrate particles, and then laminate copper foil on one side to obtain polyimide copper-clad laminate and epoxy resin copper-clad laminate. Step 3: Cut the polyimide copper-clad laminate and epoxy resin copper-clad laminate into materials, roughen the surface of the copper foil, coat with photoresist, pre-bake, expose, develop, etch, remove film, stack, vacuum press, drill, deposit copper, electroplat, make outer layer circuit, solder mask, surface treatment, shape, cut, and obtain an antistatic rigid-flex PCB board. The preparation method of the composite antistatic agent includes the following steps: Q1: Add 5,6-dibromo-1,2-dihydroacenaphthene to a container containing acetic anhydride, stir and heat, then add chromium trioxide, continue heating and stirring, then add to a container containing crushed ice, slowly add concentrated hydrochloric acid, filter under reduced pressure, wash, dry, recrystallize to obtain yellow substance 1. Q2: Under argon atmosphere, yellow substance 1, thiaanthra-1-boric acid, tetra(triphenylphosphine)palladium and tetrahydrofuran were added to a container in sequence. After heating and stirring, sodium carbonate aqueous solution was added. After heating and reacting, the mixture was cooled, extracted, dried, concentrated and evaporated to dryness, and purified to obtain dark red solid 2. Q3: Add the dark red solid 2, diaminomaleonitrile and acetic acid to the container in sequence, heat and stir under reflux, cool, pour into distilled water, filter under reduced pressure, wash, dry, purify, reflux in ethanol, filter, dry, and obtain the purplish-black solid 3. Q4: Mix the purplish-black solid 3 with an aqueous sodium hydroxide solution, heat and stir under reflux, cool, extract, adjust pH, extract again, combine the organic phases, wash, dry, filter, rotary evaporate, recrystallize, and obtain the composite antistatic agent. The photoresist is composed of 40-60 parts phenolic epoxy acrylate resin, 3-8 parts photosensitizer, 1-3 parts phthalocyanine blue, 20-40 parts diethylene glycol methyl ethyl ether, and 5-10 parts talc. The preparation method of the photosensitizer includes the following steps: S1: 2-hydroxy-5-methoxybenzaldehyde, ethyl acetoacetate and piperidine were added to a container containing anhydrous ethanol and reacted in an ice bath under nitrogen atmosphere. The mixture was then poured into deionized water for recrystallization and filtered to obtain a pale yellow solid a. S2: Add pale yellow solid a to chloroform, then add chloroform containing liquid bromine dropwise. After stirring in an ice bath, distill under reduced pressure, wash, and recrystallize to obtain solid b. S3: Add solid b, dimethyl sulfide, and silver hexafluoroantimonate to acetonitrile, stir at room temperature, filter, wash, purify and separate to obtain the photosensitizer.

2. The processing technology of the antistatic rigid-flex PCB board according to claim 1, characterized in that, In Q1, the ratio of 5,6-dibromo-1,2-dihydroacenaphthene, acetic anhydride, chromium trioxide and concentrated hydrochloric acid is (8.12-9.23) g : (380-430) mL : (21.12-23.36) g : (18-22) mL.

3. The processing technology of the antistatic rigid-flex PCB board according to claim 1, characterized in that, In Q2, the ratio of the amounts of yellow substance 1, thiazoline-1-boric acid, tetra(triphenylphosphine)palladium, tetrahydrofuran, and sodium carbonate aqueous solution is (1.38-2.06) g : (3.12-3.68) g : (0.41-0.53) g : (110-130) mL : (28-32) mL.

4. The processing technology of the antistatic rigid-flex PCB board according to claim 1, characterized in that, In Q3, the ratio of dark red solid 2, diaminomaleitrile, and acetic acid is (1.66-1.84) g : (0.21-0.36) g : (45-55) mL.

5. The processing technology of the antistatic rigid-flex PCB board according to claim 1, characterized in that, In Q4, the ratio of the amount of the purplish-black solid 3 to the sodium hydroxide aqueous solution is (2.12-2.38) g : (60-68) mL.

6. The processing technology of the antistatic rigid-flex PCB board according to claim 1, characterized in that, In S1, the ratio of 2-hydroxy-5-methoxybenzaldehyde, ethyl acetoacetate, piperidine, and anhydrous ethanol is (1.88-2.21) mL : (2.95-3.12) mL : (0.32-0.38) mL : (55-65) mL; in S2, the ratio of pale yellow solid a to liquid bromine is (1.82-1.95) g : (0.43-0.62) mL; in S3, the ratio of solid b, dimethyl sulfide, silver hexafluoroantimonate, and acetonitrile is (0.88-1.21) g : (0.21-0.32) mL : (1.21-1.33) g : (55-65) mL.

7. The processing technology of the antistatic rigid-flex PCB board according to claim 1, characterized in that, In step one, the extrusion temperature of polyimide resin particles is 280-300℃, and the extrusion temperature of epoxy resin particles is 160-190℃; in step two, the lamination temperature is 180-210℃, and the pressure is 10-20MPa; in step three, surface roughening is performed using 100mL of 150-200g / L sodium persulfate and 2-3mL of concentrated sulfuric acid, the thickness of the photoresist coating is 8-12μm, the pre-baking temperature is 75-85℃, the time is 15-25min, and the exposure energy is 150-250mJ / cm. 2 A 1 wt% sodium carbonate solution was used as the developer. During the lamination process, an epoxy resin prepreg was used as the bonding sheet. Vacuum pressing adopted a stepped heating method with a vacuum degree of -0.08 to -0.1 MPa. The temperature was increased from room temperature to 130°C and held for 5 min, then increased to 160°C and held for 7 min, then increased to 200°C and held for 10 min, and finally increased to 210°C and held for 60 min.

8. An anti-static rigid-flex PCB board, characterized in that, It is prepared using the processing technology described in any one of claims 1-7.

Images