Environment-friendly nano-coating back-drilling composite cover plate and preparation method thereof

Abstract

The present application provides an environment-friendly nano-coated back-drilling composite cover plate, comprising: a plate body; the plate body comprises a nano resin layer and a wood fiber layer, and the top of the wood fiber layer is fixedly connected to the bottom of the nano resin layer. The present application provides an environment-friendly nano-coated back-drilling composite cover plate and a preparation method thereof. The plate body made of the nano resin layer and the wood fiber layer replaces the phenolic cold punching plate, and after use, it can be recycled as ordinary solid waste, without hazardous waste treatment. The production adopts a clean process, low energy consumption, low carbon emission, and is more in line with the requirements of green manufacturing. At the same time, the hardness is moderate, the drill bit wear is reduced, the drill bit life is significantly prolonged, the back-drilling does not need to be disassembled, one thing can be used for multiple purposes, and the PCB physical partition can be directly used, reducing the material procurement and warehouse management cost. In addition, the nano resin layer has excellent cleaning effect on the drill bit, reduces the risk of wire winding, foreign matter residue, drill leakage and hole deviation, and has good guidance and stable electrical signal blocking.

Description

Technical Field

[0001] This invention relates to the field of composite cover plates, and more particularly to an environmentally friendly nano-coated back-drill composite cover plate and its preparation method. Background Technology

[0002] PCB cover plates are auxiliary materials placed on top of the board to be processed during PCB mechanical drilling. They are key consumables in the drilling process and are used in conjunction with the pads below. Their core functions are to protect the board surface, guide the drill bit, control burrs, aid heat dissipation, and improve accuracy.

[0003] Currently, phenolic cold-stamped sheets are used for PCB cover plates. However, phenolic cold-stamped sheets have high hardness, which easily wears down the drill bit and reduces its lifespan. They are also expensive to purchase and are classified as hazardous waste, resulting in high disposal costs and significant environmental risks. Furthermore, during drilling, an electrical signal is generated even before the drill bit makes contact with the PCB substrate, at which point the drilling depth is calculated, leading to drilling errors and waste.

[0004] Therefore, it is necessary to provide an environmentally friendly nano-coated back-drill composite cover plate and its preparation method to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides an environmentally friendly nano-coated back-drill composite cover plate and its preparation method, which solves the problems of high hardness, easy wear of drill bits, reduced drill bit life, high purchase price, high treatment cost and environmental risks of phenolic cold stamping plates, as well as drilling errors.

[0006] To solve the above-mentioned technical problems, the present invention provides an environmentally friendly nano-coated back-drill composite cover plate, comprising: a plate body;

[0007] The board body includes a nano-resin layer and a wood fiber layer, with the top of the wood fiber layer fixedly connected to the bottom of the nano-resin layer.

[0008] A method for preparing an environmentally friendly nano-coated back-drill composite cover plate includes the aforementioned environmentally friendly nano-coated back-drill composite cover plate. The method for preparing the environmentally friendly nano-coated back-drill composite cover plate includes the following steps:

[0009] S1: Raw material pretreatment: Select high-quality wood fibers, and successively crush, screen and remove dust to obtain clean fiber raw materials with uniform particle size. Simultaneously, nano resin slurry is mixed at high speed for 30-40 minutes until the system is uniformly mixed.

[0010] S2: Wood fiber base layer molding: The pre-treated fibers are evenly spread, hot-pressed and shaped, then cooled and demolded to obtain a flat, dense wood fiber base layer with moderate hardness.

[0011] S3: Nano-resin layer coating: The nano-resin slurry is uniformly coated onto the substrate surface using a roller coating method, with a coating thickness of approximately 0.03 mm; after coating, it is allowed to level naturally for 5-10 minutes to form a nano-resin layer;

[0012] S4: Composite curing: A segmented curing process is adopted, and the material is naturally cooled to room temperature after completion to achieve a tight composite of the nano-resin layer and the wood fiber layer;

[0013] S5: Cutting, Inspection and Packaging: Cut and process according to the usage size, and inspect the flatness of the board surface, the hardness of the board, the coating adhesion and the back drill compatibility in sequence. The qualified products are sealed and packaged for storage.

[0014] Preferably, the nano-resin slurry in step S1 includes nano-resin, environmentally friendly curing agent, and surfactant, mixed in a mass ratio of approximately 80:15:5, and water is added to adjust the solid content to 40%-45%.

[0015] Preferably, in step S2, the hot pressing temperature is 160-170℃, the pressure is 8-10MPa, and the time is 15-20min.

[0016] Preferably, the segmented curing process in step S4 includes a first segment and a second segment, wherein the first segment is pre-cured at 80°C for 10 minutes and the second segment is cured at 120°C for 20 minutes.

[0017] Preferably, in step S1, nano-montmorillonite is added to the base wood fiber and stirred until uniform.

[0018] Preferably, in step S1, nano-resin, environmentally friendly curing agent, and surfactant are taken in a mass ratio of 80:15:5, and 1.5wt% conductive carbon nanotubes, 6wt% environmentally friendly nano flame retardant, and 8wt% high-temperature resistant nano polyimide particles are compounded. After mixing, they are added to deionized water, the slurry solid content is adjusted to 42%, and high-speed stirring is carried out at 900r / min for 35min until the nano filler is completely dispersed and the slurry is completely homogeneous and free of particles, thus forming a nano-resin matrix.

[0019] Preferably, in step S1, 200-mesh ultrafine wood fibers are uniformly dispersed in a nano-resin matrix and stirred to form a composite adhesive layer in which the resin encapsulates the ultrafine fibers.

[0020] Preferably, in step S3, a composite adhesive layer is first rolled onto a bidirectional precision roller coating device to form a transition layer, which is then leveled at room temperature for 5 minutes. Subsequently, a surface nano-resin slurry is rolled onto the transition layer, and after coating, it is leveled at room temperature for 8 minutes to form a nano-resin layer.

[0021] Preferably, the thickness of the transition layer is controlled at 0.025 mm, and the total thickness of the nano-resin layer surface is controlled at 0.03 mm.

[0022] Compared with related technologies, the environmentally friendly nano-coated back-drill composite cover plate and its preparation method provided by the present invention have the following beneficial effects:

[0023] This invention provides an environmentally friendly nano-coated back-drill composite cover plate and its preparation method. The plate, made by combining a nano-resin layer with a wood fiber layer, replaces the phenolic cold-stamped board. After use, it can be recycled as ordinary solid waste without the need for hazardous waste treatment. The production process is clean, energy-saving, and low-carbon, which is more in line with the requirements of green manufacturing. At the same time, the moderate hardness reduces drill bit wear and significantly extends drill bit life. It does not need to be disassembled after back-drilling, making it multi-purpose. It can be directly used as a physical partition for PCBs, reducing material procurement and warehousing management costs. Moreover, the surface of the nano-resin layer has an excellent cleaning effect on the drill bit, reducing wire entanglement and foreign object residue, reducing the risk of missed drills and off-center holes, and providing good guidance and stable electrical signal isolation. Attached Figure Description

[0024] Figure 1 A schematic diagram of the structure of a first embodiment of an environmentally friendly nano-coated back-drill composite cover plate and its preparation method provided by the present invention;

[0025] Figure 2 A method for preparing an environmentally friendly nano-coated back-drill composite cover plate;

[0026] Figure 3 This is a schematic diagram of the structure of a second embodiment of an environmentally friendly nano-coated back-drill composite cover plate and its preparation method provided by the present invention.

[0027] The diagram is labeled as follows: 1. Board body, 11. Nano-resin layer, 12. Wood fiber layer, 2. Transition layer. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] First Embodiment

[0030] Please refer to the following: Figure 1 and Figure 2 ,in, Figure 1 A schematic diagram of the structure of a first embodiment of an environmentally friendly nano-coated back-drill composite cover plate and its preparation method provided by the present invention; Figure 2 This invention relates to a method for preparing an environmentally friendly nano-coated back-drill composite cover plate. The environmentally friendly nano-coated back-drill composite cover plate includes: a plate body 1;

[0031] The board 1 includes a nano-resin layer 11 and a wood fiber layer 12, with the top of the wood fiber layer 12 fixedly connected to the bottom of the nano-resin layer 11.

[0032] The board 1, with its double-layer structure of nano-resin layer 11 and wood fiber layer 12, perfectly combines the rigid support and surface lubricity of the material, breaking through the limitations of traditional single materials and completely replacing phenolic cold-stamped board. After use, it can be directly recycled as solid waste, while cold-stamped board requires hazardous waste treatment, resulting in a significant cost reduction. The overall cost can be reduced by 35-45%. At the same time, the hardness of phenolic cold-stamped board is too high (5H), which affects the life of the drill bit, while the board 1 has moderate hardness, effectively extending the life of the drill bit.

[0033] After the back drilling process is completed, board 1 can be used directly as a physical partition without disassembly. It can effectively isolate the PCB board and prevent physical damage such as scratches and collisions between boards, providing a reliable guarantee for production yield. The multi-purpose feature eliminates the need for the production line to purchase, store and manage special partition materials. It reduces the types of materials input from the source, which not only reduces direct procurement costs, but also greatly simplifies the complexity of production management.

[0034] A method for preparing an environmentally friendly nano-coated back-drill composite cover plate includes the aforementioned environmentally friendly nano-coated back-drill composite cover plate. The method for preparing the environmentally friendly nano-coated back-drill composite cover plate includes the following steps:

[0035] S1: Raw material pretreatment: Select high-quality wood fibers, and successively crush, screen and remove dust to obtain clean fiber raw materials with uniform particle size and no impurities. Control the moisture content to 5%-8%, and simultaneously mix nano resin slurry. Stir at high speed for 30-40 minutes until the system is uniformly mixed.

[0036] S2: Wood fiber base layer molding: The pretreated fibers are evenly spread to a thickness of about 0.25 mm, hot-pressed and shaped, then cooled and demolded to obtain a flat, dense wood fiber base layer with moderate hardness.

[0037] S3: Nano-resin layer coating: The nano-resin slurry is uniformly coated onto the substrate surface using a roller coating method, with a coating thickness of approximately 0.03 mm; after coating, it is allowed to level naturally for 5-10 minutes to form a nano-resin layer, ensuring no bubbles or missed areas.

[0038] S4: Composite curing: A segmented curing process is adopted, and the material is naturally cooled to room temperature after completion to achieve a tight composite of the nano-resin layer and the wood fiber layer;

[0039] S5: Cutting, Inspection and Packaging: Cut and process according to the usage size, and inspect the flatness of the board surface, the hardness of the board, the coating adhesion and the back drill compatibility in sequence. The qualified products are sealed and packaged for storage.

[0040] The nano-resin slurry mentioned in step S1 includes nano-resin, environmentally friendly curing agent, and surfactant, which are mixed in a mass ratio of approximately 80:15:5, and water is added to adjust the solid content to 40%-45%.

[0041] Nano-resin can also be a bio-based epoxy resin. The production scraps generated from cutting and drilling are crushed to 0.3-0.6mm, mixed evenly with wood fiber at a mass ratio of 15-20%, and then mechanically separated, activated by low-temperature plasma, and activated by nano-flocking. After being crushed and screened to 0.2-0.5mm with a moisture content of 4%-6%, 1-2% environmentally friendly hot melt adhesive powder is added as a base material for later use.

[0042] This allows for the replacement of petroleum-based resins with 30-40% bio-based resins. The materials are biodegradable, have low carbon emissions, and reduce overall costs by about 10%. They can also be reused. At the same time, the coating retains its wear resistance, self-cleaning, low friction, and anti-copper chip properties, making it suitable for the high-precision requirements of PCB back drilling.

[0043] In step S2, the hot pressing temperature is 160-170℃, the pressure is 8-10MPa, and the time is 15-20min.

[0044] The segmented curing process in step S4 includes a first segment and a second segment. The first segment is pre-cured at 80°C for 10 minutes, and the second segment is cured at 120°C for 20 minutes.

[0045] For PCBs or circuit board substrates with high precision requirements, a plate 1 needs to be placed on the surface during drilling. Due to the high precision requirements, the drill bit carries an electrical signal. If the plate 1 is not used, when the drill bit approaches the circuit board substrate, an electrical signal is generated before contact, and the drilling depth is calculated at this time, resulting in drilling errors and waste. After placing the plate 1, on the one hand, an electrical signal is generated before contact with the substrate, and the data is calculated after drilling through the nano-resin layer 11. On the other hand, it can also clean the drill bit when it returns to its position. Traditional aluminum sheet with an insulating layer does not have this effect and also avoids the disposal of hazardous waste. This product is more green and environmentally friendly, and greatly saves costs.

[0046] The working principle of the environmentally friendly nano-coated back-drill composite cover plate and its preparation method provided by this invention is as follows:

[0047] When in use, after placing the main body 1, it generates an blocking electrical signal when it is not in contact with the substrate, and starts to calculate data after drilling through the nano resin layer 11.

[0048] When the drill bit returns to its original position, the nano-resin layer 11 cleans the drill bit.

[0049] Compared with related technologies, the environmentally friendly nano-coated back-drill composite cover plate and its preparation method provided by the present invention have the following beneficial effects:

[0050] This invention provides an environmentally friendly nano-coated back-drill composite cover plate and its preparation method. The plate body 1, made by combining a nano-resin layer 11 with a wood fiber layer 12, replaces the phenolic cold-stamped plate. After use, it can be recycled as ordinary solid waste without the need for hazardous waste treatment. The production adopts a clean process, low energy consumption, and low carbon emissions, which is more in line with the requirements of green manufacturing. At the same time, the hardness is moderate, which reduces drill bit wear and significantly extends the drill bit life. After back-drilling, it does not need to be disassembled, making it multi-purpose. It can be directly used as a physical partition for PCB, reducing material procurement and warehousing management costs. Moreover, the surface of the nano-resin layer has an excellent cleaning effect on the drill bit, reducing wire entanglement and foreign matter residue, reducing the risk of missed drilling and off-center holes, and providing good guidance and stable electrical signal isolation.

[0051] Second Embodiment

[0052] Please refer to the following: Figure 3 Based on the first embodiment of this application, which provides an environmentally friendly nano-coated back-drill composite cover plate and its preparation method, the second embodiment of this application proposes another environmentally friendly nano-coated back-drill composite cover plate and its preparation method. The second embodiment is merely a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the separate implementation of the first embodiment.

[0053] Specifically, the second embodiment of this application provides an environmentally friendly nano-coated back-drill composite cover plate and its preparation method, which differs in that it also includes adding nano-montmorillonite to the base wood fiber in step S1 and stirring to mix it evenly.

[0054] In step S1, nano-resin, environmentally friendly curing agent, and surfactant are taken in a mass ratio of 80:15:5, and 1.5wt% conductive carbon nanotubes, 6wt% environmentally friendly nano flame retardant, and 8wt% high-temperature resistant nano polyimide particles are compounded. After mixing, they are added to deionized water, and the solid content of the slurry is adjusted to 42%. The mixture is stirred at 900r / min for 35min until the nano filler is completely dispersed and the slurry is completely homogeneous and free of particles, thus forming a nano-resin matrix.

[0055] The nano-resin layer is doped with 1-2% conductive carbon nanotubes to construct a continuous conductive pathway, maintaining a constant surface resistivity of 10 Ω·cm. 6 -10 9 Ω can quickly discharge static electricity from drilling friction, completely eliminate the problem of static electricity adsorption of dust and debris stuck in the hole, improve the cleanliness of the board surface and the drilled hole, and meet the PCB industry's mandatory anti-static standards.

[0056] The nano-resin layer incorporates high-temperature resistant nano-polyimide particles, increasing the continuous heat resistance temperature of the board from the traditional 120℃ to 180℃, making it suitable for high-speed drilling conditions of 30,000 rpm. The resin layer will not experience problems such as high-temperature softening, drill sticking, or burrs at the hole opening.

[0057] Adding 2-3% nano montmorillonite to the wood fiber layer seals the hydrophilic pores inside the fibers, reducing the moisture absorption and expansion rate of the board to ≤0.1%, preventing warping and deformation of the board in humid environments, and ensuring constant dimensional accuracy during long-term storage;

[0058] The nano-resin layer contains 5-8% environmentally friendly nano flame retardant, which is halogen-free and non-toxic. The flame retardant rating of the board reaches UL94V-0, making it suitable for high-safety PCB production scenarios such as servers and communication equipment, thus broadening the application range of the board.

[0059] In step S1, 200-mesh ultrafine wood fibers are uniformly dispersed in a nano-resin matrix and stirred to form a composite adhesive layer in which the resin encapsulates the ultrafine fibers.

[0060] In step S3, a composite adhesive layer is first rolled onto a bidirectional precision roller coating device to form a transition layer 2, which is then leveled at room temperature for 5 minutes. Subsequently, a surface nano-resin slurry is rolled onto the transition layer 2, and after coating, it is leveled at room temperature for 8 minutes to form a nano-resin layer.

[0061] The thickness of the transition layer 2 is controlled to be 0.025 mm, and the total thickness of the nano-resin layer surface is controlled to be 0.03 mm.

[0062] By relying on layered coating and curing parameter control, the hardness of the outer surface of the molded resin is stable at 2H, and the hardness of the inner surface near the transition layer 2 position is 1H, thus realizing a micro-nano gradient hardness structure with hardness on the outside and toughness on the inside.

[0063] The transition layer 2 has strong compatibility with the pure wood fiber base layer below (both contain wood fibers) on one side and is integrated with the pure nano resin surface layer above on the other side, perfectly filling the hardness fault of the high toughness of the wood base layer and the high hardness of the resin surface layer, eliminating interlayer delamination and drilling burrs from the root.

[0064] Compared with related technologies, the environmentally friendly nano-coated back-drill composite cover plate and its preparation method provided by the present invention have the following beneficial effects:

[0065] This invention provides an environmentally friendly nano-coated back-drilling composite cover plate and its preparation method. By forming a transition layer 2 between the nano-resin layer 11 and the wood fiber layer 12, the abrupt difference in hardness between the two layers is filled, achieving a gradual gradient change in the overall hardness of the board. During high-shear processing such as back drilling and cutting, stress can be gradually transmitted and dispersed along the gradient layer, and will not be concentrated at a single interface. This prevents interlayer tearing, delamination, hole burrs, and board peeling that occur during the processing of double-layer boards. At the same time, the smoothness of the drilled hole is greatly improved.

[0066] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An environmentally friendly nano-coated back-drill composite cover plate, characterized in that, Includes: Plate 1; The board body includes a nano-resin layer and a wood fiber layer, with the top of the wood fiber layer fixedly connected to the bottom of the nano-resin layer.

2. A method for preparing an environmentally friendly nano-coated back-drill composite cover plate, comprising the environmentally friendly nano-coated back-drill composite cover plate as described in claim 1, wherein the method for preparing the environmentally friendly nano-coated back-drill composite cover plate is required during its preparation, characterized in that... Includes the following steps: S1: Raw material pretreatment: Select high-quality wood fibers, and successively crush, screen and remove dust to obtain clean fiber raw materials with uniform particle size. Simultaneously, nano resin slurry is mixed at high speed for 30-40 minutes until the system is uniformly mixed. S2: Wood fiber base layer molding: The pre-treated fibers are evenly spread, hot-pressed and shaped, then cooled and demolded to obtain a flat, dense wood fiber base layer with moderate hardness. S3: Nano-resin layer coating: The nano-resin slurry is uniformly coated onto the substrate surface using a roller coating method, with a coating thickness of approximately 0.03 mm; after coating, it is allowed to level naturally for 5-10 minutes to form a nano-resin layer; S4: Composite curing: A segmented curing process is adopted, and the material is naturally cooled to room temperature after completion to achieve a tight composite of the nano-resin layer and the wood fiber layer; S5: Cutting, Inspection and Packaging: Cut and process according to the usage size, and inspect the flatness of the board surface, the hardness of the board, the coating adhesion and the back drill compatibility in sequence. The qualified products are sealed and packaged for storage.

3. The method for preparing an environmentally friendly nano-coated back-drill composite cover plate according to claim 2, characterized in that, The nano-resin slurry mentioned in step S1 includes nano-resin, environmentally friendly curing agent, and surfactant, which are mixed in a mass ratio of approximately 80:15:5, and water is added to adjust the solid content to 40%-45%.

4. The method for preparing an environmentally friendly nano-coated back-drill composite cover plate according to claim 2, characterized in that, In step S2, the hot pressing temperature is 160-170℃, the pressure is 8-10MPa, and the time is 15-20min.

5. The method for preparing an environmentally friendly nano-coated back-drill composite cover plate according to claim 2, characterized in that, The segmented curing process in step S4 includes a first segment and a second segment. The first segment is pre-cured at 80°C for 10 minutes, and the second segment is cured at 120°C for 20 minutes.

6. The method for preparing an environmentally friendly nano-coated back-drill composite cover plate according to claim 2, characterized in that, In step S1, nano-montmorillonite is added to the base wood fiber and stirred until uniform.

7. The method for preparing an environmentally friendly nano-coated back-drill composite cover plate according to claim 6, characterized in that, In step S1, nano-resin, environmentally friendly curing agent, and surfactant are taken in a mass ratio of 80:15:5, and 1.5wt% conductive carbon nanotubes, 6wt% environmentally friendly nano flame retardant, and 8wt% high-temperature resistant nano polyimide particles are compounded. After mixing, they are added to deionized water, and the solid content of the slurry is adjusted to 42%. The mixture is stirred at 900r / min for 35min until the nano filler is completely dispersed and the slurry is completely homogeneous and free of particles, thus forming a nano-resin matrix.

8. The method for preparing an environmentally friendly nano-coated back-drill composite cover plate according to claim 7, characterized in that, In step S1, 200-mesh ultrafine wood fibers are uniformly dispersed in a nano-resin matrix and stirred to form a composite adhesive layer in which the resin encapsulates the ultrafine fibers.

9. The method for preparing an environmentally friendly nano-coated back-drill composite cover plate according to claim 8, characterized in that, In step S3, a composite adhesive layer is first rolled onto a bidirectional precision roller coating device to form a transition layer, which is then leveled at room temperature for 5 minutes. Subsequently, a surface nano-resin slurry is rolled onto the transition layer, and after coating, it is leveled at room temperature for 8 minutes to form a nano-resin layer.

10. The method for preparing an environmentally friendly nano-coated back-drill composite cover plate according to claim 9, characterized in that, The thickness of the transition layer is controlled at 0.025 mm, and the total thickness of the nano-resin layer surface is controlled at 0.03 mm.

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