A coating method for micro i-beam skeletons

Abstract

The present application belongs to the technical field of coating, and more particularly relates to a coating method for a micro I-beam skeleton. The coating method for the micro I-beam skeleton comprises sand blasting, cleaning, pretreatment and coating. The yield of the micro I-beam skeleton after the coating process is obviously improved, the I-beam skeletons are not prone to mutual clamping and mutual sticking, the I-beam skeletons have excellent pressure insulation performance, can pass the damp heat test and the salt spray test, and have good practical application value.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and particularly relates to B05D1 / 02, and more specifically to a coating method for a micro I-shaped skeleton. Background Technology

[0002] Miniature I-beam frames are currently mainly used in the winding of miniature coils. Their I-shaped structure allows for smaller footprint and high-density stacking, resulting in thinner devices with superior performance. Applications include high-energy-density speakers, headphones, and hearing aids. Miniature I-beam frames typically use magnetic materials as the substrate, with a nickel-plated surface followed by an insulating protective coating to meet various application requirements. However, current coating processes often encounter issues such as coating adhesion, tooling sticking, or film bulging, leading to a high defect rate for miniature I-beam frames. This not only affects product performance but also significantly impacts the company's economic benefits.

[0003] Existing technology, patent CN115569823A, discloses a pyrelin coating and its preparation method. The preparation method of the pyrelin coating includes: forming a silane coupling agent transition layer on the surface of a substrate; depositing the pyrelin coating on the silane coupling agent transition layer by plasma-enhanced chemical vapor deposition. After coating, it can effectively protect electronic products and medical devices. Existing technology CN115350886A discloses a composite protective coating, its preparation method, and electronic devices. The coating device can be effectively protected by a first protective layer, a transition layer, and a second protective layer. However, the above processes neglect the pre-coating treatment step for the coated device. The lack of a pre-coating treatment step may cause the coating layer to bulge or stick together after coating, affecting the product yield. Summary of the Invention

[0004] This invention provides a coating method for a micro I-shaped skeleton, comprising the following steps:

[0005] S1. Sandblasting: Rotary sandblasting treatment is performed on the surface of the miniature I-shaped skeleton.

[0006] S2. Cleaning: Clean the sandblasted miniature I-shaped skeleton with cleaning solution;

[0007] S3. Pretreatment: The cleaned miniature I-shaped skeleton is immersed in a silane coupling agent solution.

[0008] S4. Coating: Coating the pretreated micro-I-shaped skeleton with parylene material.

[0009] Preferably, the blasting material includes one or more of the following: amorphous calcium aluminate, white fused alumina, brown fused alumina, and quartz sand.

[0010] More preferably, the blasting material includes brown fused alumina.

[0011] More preferably, the particle size of the brown fused alumina is 40-200 mesh; as an implementable example, the particle size of the brown fused alumina includes one of the following: 50 mesh, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 150 mesh, 180 mesh or 200 mesh.

[0012] Preferably, the sandblasting air pressure is 0.8 to 5 MPa; as an implementable example, the sandblasting air pressure includes one of 0.8 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa or 5 MPa.

[0013] Preferably, the direction of the rotating sandblasting is either straight or oblique.

[0014] Most micro-I-shaped skeletons on the market are currently in the micrometer range. If they are to be used in many tiny structural components such as precision instruments, microelectronics manufacturing, and biomedical devices, a protective layer needs to be coated on their surface to give them excellent biocompatibility, insulation and voltage resistance. However, after actual coating, the adhesion between the polyxylene coating and the surface of the micro-I-shaped skeleton is relatively poor, and the film layer may even bulge. In addition, due to the small volume and large specific surface area of ​​the micro-I-shaped skeleton itself, after coating, defects such as mutual jamming and mutual adhesion often occur between the micro-I-shaped skeletons, so the yield rate of the product will be significantly reduced. During the actual research and development process, the inventors unexpectedly discovered that spraying a layer of sandblasting material onto the surface of the micro-I-shaped skeleton can effectively improve the yield of the micro-I-shaped skeleton. The inventors speculate that the sandblasting material covering the micro-I-shaped skeleton can effectively promote the adhesion of parylene to the micro-I-shaped skeleton, and the bulging of the surface film will be significantly reduced. In addition, the introduction of the sandblasting layer can increase the volume of the micro-I-shaped skeleton to a certain extent and reduce the specific surface area. The contact area between the micro-I-shaped skeletons is relatively reduced, so the mutual adhesion phenomenon will also be significantly reduced, thereby improving the yield of the coated product. The present invention preferably uses sandblasting material of 40-200 mesh for sandblasting. If the particle size of the sandblasting material is too large, it will be detrimental to the subsequent cleaning and pretreatment steps, and it will be difficult to control the pressure resistance and insulation of the finished product. If the particle size of the sandblasting material is too small, it will be difficult to improve the adhesion performance of the parylene coating on the micro-I-shaped skeleton, and the film may still bulge, stick, and jam.

[0015] Preferably, the cleaning solution includes either a solvent-based cleaning solution or an aqueous cleaning solution.

[0016] Preferably, the solvent-based cleaning solution is an alcohol solvent; as an example, the alcohol solvent includes one of methanol, ethanol, isopropanol, n-butanol, 1,3-butanediol, and ethylene glycol.

[0017] More preferably, the alcohol solvent includes isopropanol.

[0018] Preferably, the aqueous cleaning solution comprises water and a treatment agent.

[0019] More preferably, the treatment agent includes benzotriazole.

[0020] More preferably, the mass ratio of benzotriazole to water is (0.3 to 1.6):100; as an implementable example, the mass ratio of benzotriazole to water includes one of 0.3:100, 0.5:100, 1:100, 1.2:100, 1.5:100 or 1.6:100.

[0021] Preferably, if the cleaning solution is an aqueous cleaning solution, the micro I-shaped skeleton also needs to be rinsed and dried using deionized water with a conductivity of less than 20 μs / cm.

[0022] Preferably, the silane coupling agent includes coupling agents containing one or more of the following functional groups: acryloyloxy functional group, allyl functional group, vinyl functional group, and alkoxysilane functional group.

[0023] More preferably, the general chemical formula of the silane coupling agent is: [RnSiO(4-n) / 2]m.

[0024] More preferably, the Si / O ratio in the silane coupling agent is 1 to 2.

[0025] More preferably, the Si / O ratio in the silane coupling agent is 1; as an example of implementation, the silane coupling agent includes one of A174, A151, and KH570.

[0026] Preferably, the solvent for the silane coupling agent solution is an alcohol solvent.

[0027] Preferably, the alcohol solvent includes one of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and ethylene glycol.

[0028] More preferably, the mass ratio of the silane coupling agent to the alcohol solvent is (0.5-3):100; as an implementable example, the mass ratio of the silane coupling agent to the alcohol solvent may include one of 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100 or 3:100.

[0029] Preferably, the silane coupling agent soaking time is 0.8 to 3.5 hours.

[0030] In this invention, using solvent-based or water-based cleaning solutions before coating the miniature I-shaped skeleton can effectively improve its safety performance. In particular, treatment with a certain concentration of benzotriazole as a water-based cleaning agent can adsorb onto the surface of the sandblasted layer, forming a protective film that blocks contact between the medium and the surface of the miniature I-shaped skeleton, thus preventing oxidation and corrosion. Simultaneously, benzotriazole also has a certain reducing property, providing electrons and neutralizing the anodic reaction on the surface of the sandblasted layer, further improving the cleaning effect. Furthermore, to improve the insulation performance of the miniature I-shaped skeleton, a secondary cleaning with deionized water (conductivity less than 20 μS / cm) is performed after cleaning with the water-based cleaning solution. This further improves the surface cleanliness of the skeleton, effectively removing impurity ions introduced by benzotriazole. This not only improves insulation performance but also allows the subsequent parylene coating to be effectively applied to the miniature I-shaped skeleton, reducing the likelihood of coating blistering and lowering the defect rate. Following the cleaning step, a pretreatment step was performed, in which the material was soaked in a silane coupling agent solution. This process improves the surface coverage and density of the parylene material on the micro I-shaped skeleton, ensures a small shrinkage value at the tip of the parylene film, significantly improves insulation withstand voltage performance, and enables the material to pass damp heat and salt spray tests, thereby enhancing the overall performance of the product.

[0031] Preferably, the par-xylene comprises one or more of the following: unsubstituted par-xylene, dichlorosubstituted par-xylene, 4,7,12,15-tetrachlorosubstituted par-xylene, 3,4,11,12-tetrachlorosubstituted par-xylene, 4,5,12,13-tetrachlorosubstituted par-xylene, 4,5,12,13-tetrabromosubstituted par-xylene, 1,1,2,2,9,9,10,10-octafluoro[2.2]dipar-xylene, or 4,5,7,8,12,13,15,16-octafluorosubstituted par-xylene.

[0032] More preferably, the par-xylene comprises one of: unsubstituted par-xylene and dichlorosubstituted par-xylene.

[0033] More preferably, the par-xylene comprises unsubstituted par-xylene.

[0034] The properties of parylene have a significant impact on the coated film. Due to environmental requirements, the coating of micro-I-shaped skeletons is typically done with halogen-free or low-halogen materials. Therefore, this invention preferably uses either unsubstituted parylene or dichlorosubstituted parylene. Furthermore, the inventors have discovered that selecting unsubstituted parylene with low water vapor and oxygen permeability as the coating material can effectively block the oxidative corrosion of the micro-I-shaped skeleton surface by water vapor and oxygen. Additionally, unsubstituted parylene exhibits a moderate crosslinking reaction rate under the action of a silane coupling agent, making the deposition coating process controllable. However, unsubstituted parylene itself has a certain viscosity, therefore, the deposition pressure and coating speed must be strictly controlled during the deposition process.

[0035] Preferably, the coating method includes one of vibration, rotation, or intermittent rotation.

[0036] Preferably, the coating fixture includes one of the following: a circular fixture, a fan-shaped fixture, and a triangular fixture.

[0037] Preferably, the total filling amount of the tooling can be selected from one of the following: 10% to 25%, 25% to 50%, 50% to 75%, or more than 75%.

[0038] More preferably, the carrier accounts for 0-75% of the total filling amount; as an implementable example, the carrier accounts for one of the following: 0%, 10%-25%, 25%-50%, 50%-75%, and more than 75% of the total filling amount.

[0039] Preferably, the coating deposition time of the parylene coating is greater than 3 hours.

[0040] More preferably, when the coating deposition occurs within the first 3 hours, the deposition pressure is controlled at 20-60 mtorr and the coating rotation speed is 1.5-3 rpm; when the coating deposition occurs after 3 hours, the deposition pressure is controlled at 60-90 mtorr and the coating rotation speed is 5-10 rpm.

[0041] Because the unsubstituted di-p-xylene (N-type pyrene) in the coating material has a certain viscosity, the deposition pressure needs to be strictly controlled during the coating deposition process. In the initial stage of coating, specifically within the first 3 hours, low pressure and low rotation speed are selected. This is mainly because the unsubstituted di-p-xylene has not yet fully coupled and formed a film under the coupling effect of the silane coupling agent. Therefore, the deposition pressure needs to be controlled at 20-60 mtorr, and the coating rotation speed at 1.5-3 rpm. After 3 hours, since the previously deposited N-type pyrene has formed a dense film, and given the viscosity of N-type pyrene itself, the coating surface is relatively smooth, making subsequent N-type pyrene deposition easier. At this point, high pressure and high rotation speed are selected, with a deposition pressure of 60-90 mtorr and a coating rotation speed of 5-10 rpm, ensuring efficient coating process.

[0042] Beneficial effects

[0043] (i) In order to improve the yield of miniature I-shaped skeletons in this invention, a specific sandblasting material is selected to coat the surface of the miniature I-shaped skeletons before coating with parylene, which can effectively reduce the defect rate and improve product quality.

[0044] (ii) In this invention, a cleaning process is performed after sandblasting, which can effectively ensure that the micro skeleton product has excellent pressure resistance and insulation performance and improve the application range of the product.

[0045] (III) In this invention, to ensure the environmental and protective performance of the micro-I-shaped skeleton, a specific parylene is selected as the coating material, which can effectively protect the micro-I-shaped skeleton.

[0046] (iv) In this invention, low pressure and low speed and high pressure and high speed are selected in the front and back sections of coating deposition, respectively, which can ensure that the coating deposition process proceeds normally and is conducive to improving the yield of micro I-shaped skeletons.

[0047] (V) The coating method described in this invention can achieve multiple functions such as protection of micro-I-shaped skeletons, insulation and withstand voltage and biocompatibility, and can avoid defects such as adhesion and tooling adhesion that are easy to occur during the coating preparation process. The test index results include: yield rate of more than 99.9%, withstand voltage of 500VDC, resistance >100MΩ, passing the damp heat test at 85℃, RH85%, 120h and passing the salt spray test at NaCl 5%, 35℃, 48h. Detailed Implementation

[0048] Example 1

[0049] This embodiment provides a coating method for a micro I-shaped skeleton, specifically comprising the following steps:

[0050] S1. Sandblasting: Use 50-mesh brown corundum to perform rotary sandblasting on the surface of the micro I-shaped skeleton. The sandblasting air pressure is 2MPa, the rotary sandblasting direction is straight, and the sandblasting time is 15min.

[0051] S2. Cleaning: Clean the sandblasted miniature I-shaped skeleton with isopropyl alcohol;

[0052] S3. Pretreatment: The cleaned micro I-shaped skeleton is immersed in a silane coupling agent solution for 2 hours. The silane coupling agent is A174 and the solvent is isopropanol. The mass ratio of A174 to isopropanol is 1:100.

[0053] S4. Coating: Unsubstituted di-p-xylene is used for coating. The coating method is rotation, using a fan-shaped tooling with a total tooling fill of 25% and no carrier. The coating pressure is 30 mtorr at 1.5 rpm for the first 3 hours and 70 mtorr at 4 rpm for the last 3 hours. The total coating thickness is 12 micrometers. The unsubstituted di-p-xylene, i.e., N-type pyrene, is a commercially available product.

[0054] Example 2

[0055] This embodiment provides a coating method for a micro I-shaped skeleton, specifically comprising the following steps:

[0056] S1. Sandblasting: Use 50-mesh brown corundum to perform rotary sandblasting on the surface of the micro I-shaped skeleton. The sandblasting air pressure is 2MPa, the rotary sandblasting direction is straight, and the sandblasting time is 15min.

[0057] S2. Cleaning: Use a water-based cleaning agent to clean the sandblasted micro I-shaped skeleton. The water-based cleaning agent is a 1 wt% benzotriazole aqueous solution. After cleaning with the water-based cleaning agent, use deionized water with a conductivity of less than 10 μs / cm to clean it.

[0058] S3. Pretreatment: The cleaned micro I-shaped skeleton is immersed in silane coupling agent for 2 hours. The silane coupling agent is A174 and the solvent is isopropanol. The mass ratio of A174 to isopropanol is 1:100.

[0059] S4. Coating: Unsubstituted di-p-xylene is used for coating. The coating method is rotation, using a fan-shaped tooling with a total tooling fill of 50% and no carrier. The deposition pressure is 40 mtorr at 2 rpm for the first 3 hours and 80 mtorr at 5 rpm for the last 3 hours. The total coating thickness is 20 micrometers. The unsubstituted di-p-xylene, i.e., N-type pyrene, is a commercially available product.

[0060] Example 3

[0061] This embodiment provides a coating method for a micro I-shaped skeleton, specifically comprising the following steps:

[0062] S1. Sandblasting: Use 50-mesh brown corundum to perform rotary sandblasting on the surface of the micro I-shaped skeleton. The sandblasting air pressure is 2MPa, the rotary sandblasting direction is straight, and the sandblasting time is 15min.

[0063] S2. Cleaning: Clean the sandblasted miniature I-shaped skeleton with isopropyl alcohol;

[0064] S3. Pretreatment: The cleaned micro I-shaped skeleton is immersed in silane coupling agent for 2 hours. The silane coupling agent is A174 and the solvent is isopropanol. The mass ratio of A174 to isopropanol is 1:100.

[0065] S4. Coating: Unsubstituted di-p-xylene is used for coating. The coating method is rotation, using a fan-shaped fixture with a total fixture filling of 75% and a carrier accounting for 25% of the total filling. The deposition pressure is 50 mtorr at 2 rpm for the first 3 hours and 90 mtorr at 5 rpm for the last 3 hours. The total coating thickness is 18 micrometers. The unsubstituted di-p-xylene, i.e., N-type pyrene, is a commercially available product.

[0066] Comparative Example 1

[0067] This comparative example provides a coating method for a micro I-shaped skeleton, specifically comprising the following steps:

[0068] S1. Sandblasting: Use 100-mesh brown corundum to perform rotary sandblasting on the surface of the micro I-shaped skeleton. The sandblasting air pressure is 2MPa, the rotary sandblasting direction is straight, and the sandblasting time is 15min.

[0069] S2. Cleaning: Clean the sandblasted miniature I-shaped skeleton with isopropyl alcohol;

[0070] S3. Pretreatment: The cleaned micro I-shaped skeleton is immersed in silane coupling agent for 2 hours. The silane coupling agent is A174 and the solvent is isopropanol. The mass ratio of A174 to isopropanol is 1:100.

[0071] S4. Coating: Coating is performed using unsubstituted di-p-xylene in a rotating manner. A fan-shaped tooling is selected, with a total tooling fill of 25% and no carrier. The deposition pressure is 80 mtorr, the rotation speed is 3 rpm, and the coating thickness is 18 micrometers. The unsubstituted di-p-xylene, i.e., N-type pyrene, is a commercially available product.

[0072] Comparative Example 2

[0073] This comparative example provides a coating method for a micro I-shaped skeleton, specifically including the following steps:

[0074] S1. Cleaning: Clean the micro I-shaped skeleton with isopropyl alcohol;

[0075] S2. Pretreatment: Immerse the cleaned micro I-shaped skeleton in a silane coupling agent for 2 h. The silane coupling agent is A174, the solvent is isopropyl alcohol, and the mass ratio of A174 to isopropyl alcohol is 1:100;

[0076] S4. Coating: Use unsubstituted parylene dimer for coating. The coating method is rotation. Select a triangular tooling. The total loading of the tooling is 25%, without a carrier; the deposition pressure is 40 mtorr, the rotation speed is 1.5 revolutions / min, and the total coating thickness is 18 microns. The unsubstituted parylene dimer, that is, N-type parylene, is a commercially available product.

[0077] Performance Evaluation

[0078] Test objects: The coated micro I-shaped skeletons described in Examples 1-3 and Comparative Examples 1-2

[0079] 1. Insulation withstand voltage test: Use a withstand voltage tester. The test voltage is 500 V (DC), the leakage current is 0.1 mA, and the two ends of the test terminals are respectively connected to the coated film area and the non-coated film area of the skeleton for testing.

[0080] 2. Surface resistance test: Use an insulation resistance tester to test the resistance of the coated film area.

[0081] 3. Salt spray test; The test conditions are 5% NaCl, 35 °C, 48 h. If there is no rust, blistering, yellowing or other corrosion phenomena on the product surface, it is recorded as qualified, otherwise it is recorded as unqualified

[0082] 4. Damp heat test: The test conditions are 85 °C, RH85%, 120 h. If there is no rust, blistering, yellowing or other corrosion phenomena on the product surface, it is recorded as qualified, otherwise it is recorded as unqualified

[0083] 5. Yield rate test: If there is no mutual adhesion or mutual jamming between the micro I-shaped skeletons and the coated film layer does not bulge, it is a good product.

[0084] Record the above test results in Table 1

[0085] Table 1

[0086]

Claims

1. A coating method for a micro I-shaped skeleton, characterized in that, Includes the following steps: S1. Sandblasting: Rotary sandblasting treatment is performed on the surface of the miniature I-shaped skeleton. S2. Cleaning: Clean the sandblasted miniature I-shaped skeleton with cleaning solution; S3. Pretreatment: The cleaned miniature I-shaped skeleton is immersed in a silane coupling agent solution. S4. Coating: Coating the pretreated micro-I-shaped skeleton with parylene material; The blasting material includes one or more of the following: amorphous calcium aluminate, white fused alumina, brown fused alumina, and quartz sand; the particle size of the brown fused alumina is 40-200 mesh; and the blasting air pressure is 0.8-5 MPa. The coating deposition time for the aforementioned parylene is greater than 3 hours; When the coating deposition occurs in the first 3 hours, the deposition pressure is controlled at 20-60 mTorr and the coating rotation speed is 1.5-3 rpm; when the coating deposition occurs after 3 hours, the deposition pressure is controlled at 60-90 mTorr and the coating rotation speed is 5-10 rpm.

2. The coating method for micro-I-shaped skeletons according to claim 1, characterized in that: The cleaning solution includes either a solvent-based cleaning solution or an aqueous cleaning solution.

3. The coating method for micro-I-shaped skeletons according to claim 1, characterized in that: The silane coupling agent solution comprises a silane coupling agent and an alcohol solvent; the silane coupling agent comprises a coupling agent containing one or more of the following functional groups: acryloyloxy functional group, allyl functional group, vinyl functional group, and alkoxysilane functional group.

4. The coating method for micro-I-shaped skeletons according to claim 3, characterized in that: The mass ratio of the silane coupling agent to the alcohol solvent is (0.5-3):

100.

5. The coating method for micro-I-shaped skeletons according to claim 1, characterized in that: The aforementioned parylenes include one or more of the following: unsubstituted parylene, dichlorosubstituted parylene, 4,7,12,15-tetrachlorosubstituted parylene, 3,4,11,12-tetrachlorosubstituted parylene, 4,5,12,13-tetrachlorosubstituted parylene, 4,5,12,13-tetrabromosubstituted parylene, 1,1,2,2,9,9,10,10-octafluoro[2.2]diparylene, and 4,5,7,8,12,13,15,16-octafluorosubstituted parylene.

6. The coating method for a micro I-shaped skeleton according to claim 5, characterized in that: The aforementioned par-xylene includes one of unsubstituted par-xylene and dichlorosubstituted par-xylene.

7. The coating method for a micro-I-shaped skeleton according to claim 6, characterized in that: The aforementioned par-xylene includes unsubstituted par-xylene.

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