Protective layer coating method of stepped golden finger three-dimensional structure

Abstract

The invention relates to a protective layer coating method of a stepped golden finger three-dimensional structure. The protective layer coating method comprises the following steps: step 1, surface activating treatment: performing plasma cleaning on the surface of a printed circuit board; step 2, coating a three-dimensional curved surface: adopting non-contact spraying equipment, coating a protective material in sections along the height change direction of the step structure of the golden finger, independently controlling the coating amount of each section, and forming an inclined angle between a dispensing head and the plate surface during coating; and step 3, step curing treatment: carrying out ultraviolet light curing on the coating area. The invention provides a method for coating a protective layer of a stepped golden finger three-dimensional structure. The core of the method is to solve the covering problem of a stepped region through segmented control and non-contact coating.

Description

Technical Field

[0001] The present invention relates to printed circuit board manufacturing technology, and specifically to a protective layer coating method for a three-dimensional structure of stepped gold fingers, which is particularly suitable for the field of manufacturing high-density interconnected AI computing power cards. Background Art

[0002] In the manufacturing of high-end AI computing cards, stepped gold finger structures commonly exhibit three-dimensional height differences of 0.1-0.5mm due to the need for high-density interconnection and thinness. Traditional flat coating processes (such as screen printing and spray coating) struggle to effectively cover such complex geometric surfaces, especially in sloped transition areas, where problems such as uneven protective layer thickness and incomplete edge coverage often occur. Existing solutions have attempted to improve coverage through multiple coatings or adjusting material viscosity, but these approaches still have significant limitations: multiple coatings can easily lead to material accumulation, affecting dimensional accuracy; high-viscosity materials have poor wettability on sloped surfaces, easily creating microvoids; and low-viscosity materials can cause sagging due to their excessive fluidity. Furthermore, defects in the protective layer at the interface between the copper layer and the substrate in the stepped areas exposed after laser windowing can lead to electrochemical migration or signal interference. Therefore, there is an urgent need to develop a precision coating technology that adapts to three-dimensional microstructures and achieves continuous and complete protective layer coverage while ensuring production efficiency. Summary of the Invention

[0003] In view of this, the present invention provides a protective layer coating method for a three-dimensional structure of a stepped gold finger, the core of which is to solve the coverage problem of the step area through segmented control and non-contact coating.

[0004] The purpose of the present invention is achieved through the following technical solutions: A method for coating a protective layer of a three-dimensional structure of a stepped gold finger, comprising the following steps: Step 1: Surface activation treatment: plasma cleaning of the printed circuit board surface; Step 2: 3D curved surface coating: Use non-contact spraying equipment to apply protective material in sections along the height change direction of the gold finger step structure. The coating amount is independently controlled in each section, and the dispensing head is tilted at an angle to the board surface during coating. Step 3: Step curing: UV curing of the coated area.

[0005] This method solves the technical challenge of protective layer coverage in the stepped gold finger area through an innovative three-dimensional curved surface coating process. First, plasma cleaning is used to activate the surface of the printed circuit board, effectively removing microscopic contaminants and enhancing surface energy, providing an excellent adhesion foundation for subsequent protective materials. The core innovation lies in the three-dimensional curved surface coating stage. A non-contact spray device is used to perform segmented coating operations along the height variation direction of the gold finger step structure. The coating amount is independently controlled in each segment, while the dispensing head maintains a working posture at an inclined angle to the board surface. This combined technical means enables the protective material to accurately cover complex three-dimensional geometric surfaces that are difficult to handle with traditional processes.

[0006] Finally, a step-curing process achieves a stable protective layer, while UV curing rapidly completes the cross-linking reaction. This method overcomes the limitations of flat coating processes, forming a continuous and uniform protective layer on complex three-dimensional surfaces. This prevents defects such as exposed copper and substrate, significantly improving product reliability and service life. This process does not require modifications to existing production line equipment, making implementation costs manageable and suitable for mass production of high-density interconnect printed circuit boards.

[0007] Preferably, the protective material in step 2 of three-dimensional curved surface coating is a UV-curable dielectric resin material.

[0008] Using a UV-curable dielectric resin material as a protective layer provides excellent electrical insulation and mechanical protection. This material rapidly cures under UV light, significantly shortening production cycles and improving manufacturing efficiency. Dielectric resin materials exhibit excellent dielectric constant and dielectric loss characteristics, meeting high-frequency signal transmission requirements while avoiding adverse effects on the electrical performance of gold fingers. Furthermore, this type of material exhibits a high degree of thermal expansion matching that of the printed circuit board substrate, making it less susceptible to cracking or delamination in temperature-sensitive environments. The UV-curing properties also eliminate the risk of thermal damage to the substrate that can occur with traditional thermal curing, making it particularly suitable for protecting temperature-sensitive precision electronic components.

[0009] Preferably, the dielectric resin material has the characteristic of low linear shrinkage after curing.

[0010] Dielectric resin materials with low linear shrinkage maintain dimensional stability during the curing process, preventing stress concentration or microcracks at the interface between the protective layer and the substrate due to volume shrinkage. This property ensures uniform and continuous coverage of the protective layer on the complex three-dimensional surface of the stepped gold finger, without thinning or breaking the protective layer at corners or edges. Low shrinkage materials also maintain precise geometry, preventing excessive shrinkage of the protective layer that could expose metal areas that should be covered. This characteristic also helps maintain the surface flatness of the protective layer, providing a good process foundation for subsequent assembly steps and reducing assembly defects caused by surface unevenness.

[0011] Preferably, in step 2, the three-dimensional curved surface coating is performed by a piezoelectric precision injection valve, and the injection valve is kept in non-contact with the substrate during coating.

[0012] The piezoelectric precision jet valve can achieve precise material metering at the microliter level, ensuring the precise deposition of protective materials on complex three-dimensional surfaces. The non-contact coating method significantly reduces the scratches or contamination that may be caused to the gold finger surface by mechanical contact, maintaining the high cleanliness and integrity of the gold finger area. The jet valve has a fast response characteristic and can cooperate with the segmented coating process to achieve independent material control of each section to meet the differentiated requirements of different areas for the thickness of the protective layer. The non-contact operation also eliminates the material tailing or drawing phenomenon that may be caused by traditional contact dispensing, ensuring that the edges of the protective layer are clear and neat. This combination of technologies is particularly suitable for processing high-value, high-precision electronic components, significantly reducing the risk of product damage during the manufacturing process.

[0013] Preferably, step 2 of three-dimensional curved surface coating specifically includes: The step structure is divided into a high-level plane area with an inclined transition zone and a low-level plane area; The coating amount per unit area in the inclined transition area is greater than the coating amount per unit area in the flat area.

[0014] By clearly dividing the step structure into a high-level plane area, an inclined transition area, and a low-level plane area, a targeted coating strategy can be implemented. In particular, the coating amount per unit area is increased in the inclined transition area, which effectively compensates for the tendency of material flow in this area due to gravity, ensuring the formation of a protective layer of sufficient thickness. This partitioned differentiated control overcomes the inherent challenges of three-dimensional inclined surface material coverage and avoids insufficient protective layer thickness or material accumulation in inclined areas. The increased coating amount just offsets the flow effect of the material on the inclined surface, so that the thickness of the protective layer finally formed remains uniform across the entire surface of the step structure. This technical approach solves the key issue of uniformity of protective layers for complex geometric shapes while ensuring efficient material use.

[0015] Preferably, in step 2, the three-dimensional curved surface coating is performed by variable speed coating in the area connection section, including reducing the moving speed and extending the positioning time.

[0016] Variable-speed coating is implemented at the junction of the zones, reducing the travel speed and extending the positioning time to ensure sufficient deposition and uniform distribution of the protective material in critical transition areas. Reducing the travel speed allows the material sufficient time to wet the substrate surface, improving interfacial bonding quality; extending the positioning time ensures complete coverage of the material at complex geometric intersections. This dynamic control strategy effectively prevents material accumulation or incomplete coverage at the junction of zones, achieving a smooth transition of the protective layer between different areas of the stepped structure. This technical approach specifically optimizes coverage at the intersection of inclined surfaces and flat surfaces, avoiding the formation of weak links or stress concentration points at these critical locations.

[0017] Preferably, charged particle flow is used to remove surface contaminants before coating.

[0018] Before coating, a charged particle stream is used to remove surface contaminants, removing microscopic particles and organic residues that affect the adhesion of the protective layer. This cleaning method does not produce mechanical contact, thus avoiding damage to the delicate gold finger structure. The charged particles effectively neutralize surface static electricity, preventing the adsorption of airborne dust and maintaining the cleanliness of the operating environment. The cleaned surface has a more uniform surface energy distribution, which improves the wettability and spreadability of the protective material, thereby enhancing the interfacial bonding strength between the protective layer and the substrate. This pretreatment step ensures that the subsequent protective layer forms a continuous, defect-free coverage, reducing quality issues such as localized peeling or bubbles in the protective layer caused by surface contamination.

[0019] Preferably, the step 3 step curing process includes performing supplementary curing on the optical shielding area of ​​the step structure.

[0020] Supplemental curing is performed on the optically shielded areas of the stepped structure to ensure that these areas, which are not exposed to sufficient UV radiation, are still fully cured. This measure solves the technical problem of insufficient curing in the shadow areas of the three-dimensional structure, avoiding quality defects such as stickiness on the surface of the protective layer or insufficient internal curing. Supplemental curing enables the entire protective layer to form a uniform cross-linked network structure, ensuring the consistency of material properties in all areas of the three-dimensional surface. This step-curing strategy specifically optimizes the curing effect under complex geometric structures, eliminates the performance differences of the protective layer caused by uneven lighting, and significantly improves the long-term reliability of the product in harsh environments.

[0021] Preferably, the coating operation is carried out in an environment with stable temperature and humidity control.

[0022] Performing coating operations in a temperature and humidity-controlled environment eliminates environmental fluctuations that can interfere with the protective material's fluidity and curing behavior. Temperature stability ensures the material maintains the desired viscosity, preventing inaccurate coating control due to temperature fluctuations. Humidity control prevents moisture in the air from affecting material properties or causing premature curing. A stable environment ensures consistent process parameters and improves batch-to-batch quality. This environmental control measure is particularly beneficial in the manufacture of precision electronic components, reducing process fluctuations caused by environmental factors and ensuring repeatable and reliable protective coating formation.

[0023] Preferably, the dielectric resin material maintains a viscosity state that suppresses fluidity during coating.

[0024] The dielectric resin material maintains a flow-inhibiting viscosity during coating, effectively controlling its flow behavior on three-dimensional surfaces. This viscosity prevents excessive material flow on inclined surfaces, ensuring precise protective layer geometry. This flow-inhibiting state maintains positional stability after deposition, preventing material sagging or coverage beyond the designed range. This characteristic also reduces material migration into non-target areas, maintaining the sharpness of gold finger edges. This optimized viscosity provides ideal material performance for complex three-dimensional structures and is a key material property for achieving precise protective layer coverage.

[0025] The beneficial effects of the present invention compared to the prior art are: 1. Improved three-dimensional surface adaptability: A segmented coating strategy along the height variation, combined with controlled dispensing head tilt angle, significantly improves protective layer coverage on surfaces with complex step structures. The segmented independent control technology allows for differentiated adjustment of material deposition based on the geometric characteristics of the high-level planar area, inclined transition area, and low-level planar area. The tilted dispensing operation enhances the material's wetting and spreading ability on inclined surfaces. This dynamic adjustment mechanism helps achieve uniform distribution of protective layer thickness in a single coating pass, reducing coverage blind spots and material accumulation that are common in inclined areas with traditional processes.

[0026] 2. Enhanced Interface Bonding Reliability: The combined application of surface plasma activation pretreatment and low-shrinkage dielectric resin materials helps optimize the bond quality between the protective layer and the substrate. Plasma cleaning not only removes microscopic contaminants but also activates chemical bonds on the substrate surface, improving the wettability of the resin material. Simultaneously, the low linear shrinkage suppresses interfacial stress during the curing process, reducing the risk of the protective layer peeling off from steep step edges. This synergistic effect provides more stable, long-term protection for high-reliability electronic devices.

[0027] 3. Enhanced process stability: The combination of non-contact piezoelectric injection and variable-speed coating control improves manufacturing consistency. The micro-scale precision metering of the piezoelectric valve reduces material waste, and the non-contact mode avoids mechanical damage to the delicate gold fingers. The speed reduction and delay strategy in the zone transition section optimizes material flow in the transition zone, reducing coating defects caused by sudden speed changes. Combined with a temperature and humidity-controlled environment, this process demonstrates excellent batch-to-batch stability, providing a technical foundation for mass production applications.

[0028] 4. Guaranteed complete cure: Targeting optically shadowed areas unique to three-dimensional structures, a supplemental curing mechanism helps eliminate the potential for insufficient cure in shadowed areas. Energy compensation through secondary UV irradiation promotes the formation of a fully cross-linked network in the protective layer at the bottom of deep grooves or steep slopes, preventing viscosity or electrical degradation caused by uncured resin. This step-by-step curing strategy provides more comprehensive material performance assurance for complex structures. DETAILED DESCRIPTION Example 1

[0029] This embodiment provides a method for coating a protective layer of a three-dimensional structure of a stepped gold finger, comprising the following steps: Step 1: Surface activation treatment: plasma cleaning of the printed circuit board surface; Step 2: 3D curved surface coating: Use non-contact spraying equipment to apply protective material in sections along the height change direction of the gold finger step structure. The coating amount is independently controlled in each section, and the dispensing head is tilted at an angle to the board surface during coating. Step 3: Step curing: UV curing of the coated area.

[0030] This method solves the technical challenge of protective layer coverage in the stepped gold finger area through an innovative three-dimensional curved surface coating process. First, plasma cleaning is used to activate the surface of the printed circuit board, effectively removing microscopic contaminants and enhancing surface energy, providing an excellent adhesion foundation for subsequent protective materials. The core innovation lies in the three-dimensional curved surface coating stage. A non-contact spray device is used to perform segmented coating operations along the height variation direction of the gold finger step structure. The coating amount is independently controlled in each segment, while the dispensing head maintains a working posture at an inclined angle to the board surface. This combined technical means enables the protective material to accurately cover complex three-dimensional geometric surfaces that are difficult to handle with traditional processes.

[0031] Finally, a step-curing process achieves a stable protective layer, while UV curing rapidly completes the cross-linking reaction. This method overcomes the limitations of flat coating processes, forming a continuous and uniform protective layer on complex three-dimensional surfaces. This prevents defects such as exposed copper and substrate, significantly improving product reliability and service life. This process does not require modifications to existing production line equipment, making implementation costs manageable and suitable for mass production of high-density interconnect printed circuit boards.

[0032] In this embodiment, the protective material in step 2 of three-dimensional curved surface coating is a UV-curable dielectric resin material.

[0033] Using a UV-curable dielectric resin material as a protective layer provides excellent electrical insulation and mechanical protection. This material rapidly cures under UV light, significantly shortening production cycles and improving manufacturing efficiency. Dielectric resin materials exhibit excellent dielectric constant and dielectric loss characteristics, meeting high-frequency signal transmission requirements while avoiding adverse effects on the electrical performance of gold fingers. Furthermore, this type of material exhibits a high degree of thermal expansion matching that of the printed circuit board substrate, making it less susceptible to cracking or delamination in temperature-sensitive environments. The UV-curing properties also eliminate the risk of thermal damage to the substrate that can occur with traditional thermal curing, making it particularly suitable for protecting temperature-sensitive precision electronic components.

[0034] In this embodiment, the dielectric resin material has the characteristic of low linear shrinkage after curing.

[0035] Dielectric resin materials with low linear shrinkage maintain dimensional stability during the curing process, preventing stress concentration or microcracks at the interface between the protective layer and the substrate due to volume shrinkage. This property ensures uniform and continuous coverage of the protective layer on the complex three-dimensional surface of the stepped gold finger, without thinning or breaking the protective layer at corners or edges. Low shrinkage materials also maintain precise geometry, preventing excessive shrinkage of the protective layer that could expose metal areas that should be covered. This characteristic also helps maintain the surface flatness of the protective layer, providing a good process foundation for subsequent assembly steps and reducing assembly defects caused by surface unevenness.

[0036] In this embodiment, the three-dimensional curved surface coating in step 2 is performed by a piezoelectric precision injection valve, and the injection valve is kept in non-contact with the substrate during the coating process.

[0037] The piezoelectric precision jet valve can achieve precise material metering at the microliter level, ensuring the precise deposition of protective materials on complex three-dimensional surfaces. The non-contact coating method significantly reduces the scratches or contamination that may be caused to the gold finger surface by mechanical contact, maintaining the high cleanliness and integrity of the gold finger area. The jet valve has a fast response characteristic and can cooperate with the segmented coating process to achieve independent material control of each section to meet the differentiated requirements of different areas for the thickness of the protective layer. The non-contact operation also eliminates the material tailing or drawing phenomenon that may be caused by traditional contact dispensing, ensuring that the edges of the protective layer are clear and neat. This combination of technologies is particularly suitable for processing high-value, high-precision electronic components, significantly reducing the risk of product damage during the manufacturing process.

[0038] In this embodiment, step 2 of three-dimensional curved surface coating specifically includes: The step structure is divided into a high-level plane area with an inclined transition zone and a low-level plane area; The coating amount per unit area in the inclined transition area is greater than the coating amount per unit area in the flat area.

[0039] By clearly dividing the step structure into a high-level plane area, an inclined transition area, and a low-level plane area, a targeted coating strategy can be implemented. In particular, the coating amount per unit area is increased in the inclined transition area, which effectively compensates for the tendency of material flow in this area due to gravity, ensuring the formation of a protective layer of sufficient thickness. This partitioned differentiated control overcomes the inherent challenges of three-dimensional inclined surface material coverage and avoids insufficient protective layer thickness or material accumulation in inclined areas. The increased coating amount just offsets the flow effect of the material on the inclined surface, so that the thickness of the protective layer finally formed remains uniform across the entire surface of the step structure. This technical approach solves the key issue of uniformity of protective layers for complex geometric shapes while ensuring efficient material use.

[0040] In this embodiment, in step 2, the three-dimensional curved surface coating is performed at a variable speed in the area connection section, including reducing the moving speed and extending the positioning time.

[0041] Variable-speed coating is implemented at the junction of the zones, reducing the travel speed and extending the positioning time to ensure sufficient deposition and uniform distribution of the protective material in critical transition areas. Reducing the travel speed allows the material sufficient time to wet the substrate surface, improving interfacial bonding quality; extending the positioning time ensures complete coverage of the material at complex geometric intersections. This dynamic control strategy effectively prevents material accumulation or incomplete coverage at the junction of zones, achieving a smooth transition of the protective layer between different areas of the stepped structure. This technical approach specifically optimizes coverage at the intersection of inclined surfaces and flat surfaces, avoiding the formation of weak links or stress concentration points at these critical locations.

[0042] In this embodiment, charged particle flow is used to remove surface contaminants before coating.

[0043] Before coating, a charged particle stream is used to remove surface contaminants, removing microscopic particles and organic residues that affect the adhesion of the protective layer. This cleaning method does not produce mechanical contact, thus avoiding damage to the delicate gold finger structure. The charged particles effectively neutralize surface static electricity, preventing the adsorption of airborne dust and maintaining the cleanliness of the operating environment. The cleaned surface has a more uniform surface energy distribution, which improves the wettability and spreadability of the protective material, thereby enhancing the interfacial bonding strength between the protective layer and the substrate. This pretreatment step ensures that the subsequent protective layer forms a continuous, defect-free coverage, reducing quality issues such as localized peeling or bubbles in the protective layer caused by surface contamination.

[0044] In this embodiment, step 3 of the step curing process includes performing supplementary curing on the optical shielding area of ​​the step structure.

[0045] Supplemental curing is performed on the optically shielded areas of the stepped structure to ensure that these areas, which are not exposed to sufficient UV radiation, are still fully cured. This measure solves the technical problem of insufficient curing in the shadow areas of the three-dimensional structure, avoiding quality defects such as stickiness on the surface of the protective layer or insufficient internal curing. Supplemental curing enables the entire protective layer to form a uniform cross-linked network structure, ensuring the consistency of material properties in all areas of the three-dimensional surface. This step-curing strategy specifically optimizes the curing effect under complex geometric structures, eliminates the performance differences of the protective layer caused by uneven lighting, and significantly improves the long-term reliability of the product in harsh environments.

[0046] In this embodiment, the coating operation is performed in a temperature and humidity stable controlled environment.

[0047] Performing coating operations in a temperature and humidity-controlled environment eliminates environmental fluctuations that can interfere with the protective material's fluidity and curing behavior. Temperature stability ensures the material maintains the desired viscosity, preventing inaccurate coating control due to temperature fluctuations. Humidity control prevents moisture in the air from affecting material properties or causing premature curing. A stable environment ensures consistent process parameters and improves batch-to-batch quality. This environmental control measure is particularly beneficial in the manufacture of precision electronic components, reducing process fluctuations caused by environmental factors and ensuring repeatable and reliable protective coating formation.

[0048] In this embodiment, the dielectric resin material maintains a viscosity state that suppresses fluidity when applied.

[0049] The dielectric resin material maintains a flow-inhibiting viscosity during coating, effectively controlling its flow behavior on three-dimensional surfaces. This viscosity prevents excessive material flow on inclined surfaces, ensuring precise protective layer geometry. This flow-inhibiting state maintains positional stability after deposition, preventing material sagging or coverage beyond the designed range. This characteristic also reduces material migration into non-target areas, maintaining the sharpness of gold finger edges. This optimized viscosity provides ideal material performance for complex three-dimensional structures and is a key material property for achieving precise protective layer coverage. Example 2

[0050] Implementation case of AI computing power card step gold finger protective layer coating In the manufacturing of printed circuit board AI computing power cards, due to the three-dimensional height difference of 0.1 to 0.5 mm in the stepped gold finger area, precision coating technology is used to overcome the flow problem of materials in the high and low drop areas. The specific process flow is as follows: 1. Pre-processing stage Plasma cleaning technology is used to activate the surface of printed circuit boards and enhance the bonding strength of the protective layer.

[0051] 2. Material selection and parameter control 1. Material properties: Select a UV-curable dielectric resin material (the color should be the same or similar to the substrate); the material must have high adhesion and low linear shrinkage. During coating, the viscosity should be controlled within the range of approximately 12000±2000cP·s to suppress fluidity.

[0052] 2. Equipment configuration: It uses a non-contact piezoelectric injection valve with a minimum glue dispensing accuracy of 0.001 ml; the gap between the nozzle and the substrate is set to 0.12 to 0.18 mm to avoid mechanical contact damage to the gold fingers.

[0053] 3. Segmented coating process 1. 3D Path Planning: The Gold Finger step structure is divided into three zones: a high-level flat area (Zone A), an inclined transition zone (Zone B), and a low-level flat area (Zone C). Zone B increases the coating volume per unit area by 10% to 30% to compensate for gravity-induced material flow. Variable speed control is implemented in the transition zone: the travel speed is reduced to 3 to 5 mm / s, and the positioning time is extended by 10 to 20 milliseconds.

[0054] 2. Key operating parameters: The ink dot diameter is designed to be 1.5 times the step height difference (for example, a 0.3 mm ink dot is used when the height difference is 0.2 mm); the dispensing head inclination angle is controlled within the range of 15° to 30°, and the optimal angle is determined through first-piece debugging; the coating safety distance is strictly limited (a ≥0.2 mm material-free area is reserved at the edge of the gold finger).

[0055] 4. Environment and process control 1. Cleanliness control: Use ion wind dust removal technology to remove metal debris before coating.

[0056] 2. Temperature and humidity control: The ambient temperature is stabilized at 22±2℃, and the humidity is maintained at 45% to 65%RH.

[0057] 3. Anti-pollution measures: Ensure that the material is strictly prohibited from covering the gold finger contact area.

[0058] 5. Step Curing Process 1. Main curing stage: UV wavelength 365 nm, irradiation energy 800 to 1200 mJ / cm2; 2. Supplementary curing: Apply secondary UV irradiation to the optically shielded area of ​​the step structure to ensure complete cross-linking of the three-dimensional surface.

[0059] 6. Technical Advantages This embodiment solves the industry problem of three-dimensional stepped structure coating through the following core means: 1. Differentiated material distribution: Based on the increment of zone B and regional speed control, uniform coverage of the inclined surface is achieved; 2. Precision measurement: The non-contact operation of the piezoelectric injection valve avoids damage to the gold finger and accurately matches the micron-level height difference; 3. Dual-stage curing mechanism: main curing combined with shadow area reinforcement to ensure the performance consistency of the three-dimensional structural protective layer; 4. Environmental stability: Closed-loop control of temperature and humidity maintains the rheological properties of the material and improves process repeatability.

[0060] This implementation case fully verifies the feasibility of this method in the manufacture of high-density interconnect structures for AI computing power cards, and is particularly suitable for the field of electronic component protection that requires micron-level precision.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for coating a protective layer of a three-dimensional structure of a stepped gold finger, characterized in that: The following steps are involved: Step 1: Surface activation treatment: plasma cleaning of the printed circuit board surface; Step 2: 3D curved surface coating: Use non-contact spraying equipment to apply protective material in sections along the height change direction of the gold finger step structure. The coating amount is independently controlled in each section, and the dispensing head is tilted at an angle to the board surface during coating. Step 3: Step curing: UV curing of the coated area.

2. The protective layer coating method for a three-dimensional structure of a stepped gold finger according to claim 1, characterized in that: The protective material in step 2 is a UV-curable dielectric resin material.

3. The protective layer coating method for the stepped gold finger three-dimensional structure according to claim 2, characterized in that: The dielectric resin material has the characteristic of low linear shrinkage after curing.

4. The protective layer coating method for a three-dimensional structure of a stepped gold finger according to claim 1, characterized in that: In step 2, the coating operation is performed by a piezoelectric precision injection valve, and the injection valve is kept in non-contact with the substrate during coating.

5. The protective layer coating method for a three-dimensional structure of a stepped gold finger according to claim 1, characterized in that: Step 2 specifically includes: The step structure is divided into a high-level plane area, an inclined transition area and a low-level plane area; The coating amount per unit area in the inclined transition area is greater than the coating amount per unit area in the flat area.

6. The protective layer coating method for a three-dimensional structure of a stepped gold finger according to claim 1, characterized in that: Step 2 implements variable speed coating in the area connection section, including reducing the moving speed and extending the positioning time.

7. The protective layer coating method for a three-dimensional structure of a stepped gold finger according to claim 1, characterized in that: Charged particle flow is used to remove surface contaminants before coating.

8. The protective layer coating method for a three-dimensional structure of a stepped gold finger according to claim 1, characterized in that: Step 3 includes performing supplementary curing on the optically shielding area of ​​the step structure.

9. The protective layer coating method for a three-dimensional structure of a stepped gold finger according to claim 1, characterized in that: The coating operation is carried out in a temperature and humidity controlled environment.

10. The protective layer coating method for a three-dimensional structure of a stepped gold finger according to claim 2, characterized in that: The dielectric resin material maintains a viscosity state that suppresses fluidity when applied.