CN116017967B - Preparation method of masking liquid, random crack template and electromagnetic shielding optical window - Google Patents

Abstract

The invention belongs to the technical field of electromagnetic shielding optical windows, and particularly relates to a mask liquid, a random crack template and a preparation method of an electromagnetic shielding optical window. The preparation method of the mask liquid comprises the following steps: and (3) preserving heat of a mixed solution of the monomer mixture, the emulsifier and the initiator at 80-85 ℃, cooling, adjusting the pH value to be neutral after cooling to room temperature, filtering with 400-500 mesh filter cloth or a filter membrane, and collecting filtrate as mask liquid. The preparation method of the random crack template and the electromagnetic shielding optical window is to prepare the mask liquid. The invention can solve the problems that the machining cannot be realized and the laser etching cost is high in the processing and manufacturing of the metal mesh electromagnetic shielding optical window with the random crack width of less than 3mm at present.

Description

Preparation method of masking liquid, random crack template and electromagnetic shielding optical window

technical field

The invention belongs to the technical field of electromagnetic shielding optical windows, and in particular relates to a mask liquid for preparing electromagnetic shielding optical fiber windows, a corresponding random crack template and a preparation method of electromagnetic shielding optical windows.

Background technique

Electromagnetic shielding optical window is the core functional element to ensure the normal operation of optoelectronic instruments and equipment in the environment of microwave and electromagnetic pulse radiation, such as display screens of electronic instruments for various purposes, aircraft and vehicle windows, photodetector systems, etc.

The metal grid type electromagnetic shielding optical window is a transparent optical window device that attenuates electromagnetic wave radiation through a metal grid. The method of realizing the electromagnetic shielding performance of the metal grid electromagnetic shielding optical window is mainly to plate a metal grid with good conductivity on the optical glass substrate. Common preparation methods for regular shapes include ultraviolet lithography, ion beam etching, chemical etching, laser direct writing, electroplating, and self-assembly methods. These preparation methods all require expensive writing equipment, and the process is complicated.

For metal grids with irregular shapes and structures, the random crack template method is usually used to prepare. Compared with the above methods, the random crack template method has unique advantages such as short process flow, no need for large precision equipment, and low cost, which overcomes the traditional metal mesh. The complexity of the gate film process and the high dependence on equipment.

The random crack template preparation method is to apply the mask liquid on the optical window glass to form a mask layer. After the mask layer dries, suitable cracks (including several cracks of different lengths and several cracks) will be produced on the surface of the optical glass. Cracks of different lengths are randomly distributed to form multiple grids), and after the metal grid is plated in the crack and the mask layer is removed, it becomes a template for plating the metal grid, as shown in Figure 1.

The design and preparation process of the random crack template play a vital role in the electromagnetic shielding performance. The width and depth of the crack on the template will directly affect the line width and thickness of the subsequent metal grid, which in turn affects the electromagnetic shielding ability of the metal grid. This is a very important link in the formation process of the random type electromagnetic shielding grid.

The existing random crack template preparation techniques mainly include spin coating method, pulling method or spray coating method. In these processes, the main factors that affect the crack width, crack width consistency, crack connectivity, grid size, grid distribution uniformity, and template flatness of the crack template are the masking fluid, the masking fluid itself The nature of the mask mainly determines the performance of the template for forming cracks. Commonly used masking solutions include TiO ₂ sol, gelatin, crack nail polish containing acrylic resin, egg white, etc.

For example, the prior art CN201310122824.1 and the document Uniformself-forming metallic network as a high-performance transparent conductive electrode describe crack templates for transparent conductive electrodes made of microcrystalline TiO ₂ as a mask liquid, and the TiO ₂ template removal process uses a mechanical friction method. The fine control of the mechanical friction process is difficult, which may cause incomplete removal of the template or excessive friction, which will affect the light transmittance and optical quality of the substrate.

In CN201510262998.7, the cracked nail polish CA600 containing acrylic resin, CN201910315144.9 and CN202210565512.7 were used to prepare mask templates with water-based acrylic emulsion. Because the components of commercially available products are fixed, the adjustable parameters and The range is very limited, the crack line width and period parameters of the prepared crack template are relatively fixed, and the crack template grid uniformity and crack connectivity are of low quality. There are great limitations in the use of photoelectric equipment with high requirements.

In summary, the existing random crack templates have low quality of crack template grid uniformity and crack connectivity, resulting in poor light transmittance and optical quality of the later window.

Contents of the invention

Aiming at the defects or deficiencies of the prior art, the present invention provides a masking liquid in one aspect.

For this reason, the preparation method of the masking liquid provided by the present invention includes: keeping the mixture of monomer mixture, emulsifier and initiator at 80-85°C and then cooling it, and then adjusting the pH value to neutral after cooling to room temperature. After that, filter with 400~500 mesh filter cloth or membrane, and collect the filtrate as masking liquid;

The monomer mixture is a mixture of methyl methacrylate, n-butyl acrylate, hydroxypropyl acrylate, methacrylic acid and styrene;

The emulsifier is an aqueous solution of allyloxy-2-hydroxypropane sulfonate sodium and dodecylphenol polyoxyethylene ether, or an allyloxy-fatty alcohol oxyethylene ether sodium sulfonate and dodecylphenol An aqueous solution of phenol polyoxyethylene ether, or an aqueous solution of disodium glycolate sulfinate and dodecylphenol polyoxyethylene ether;

The initiator is an aqueous solution of 1,1,3,3-tetramethylperoxybutyl-2-ethylhexanoate.

Optionally, the preparation method of the mixed liquid of the monomer mixture, emulsifier and initiator comprises: after mixing the emulsifier and part of the monomer mixture, adjust the pH value to neutral, mix and heat to 70-75°C, then add part of the initiator, continue to heat up to 75-80°C and keep warm, then add the remaining amount of monomer mixture and the remaining amount of initiator to mix and keep warm. A further optional solution is that the partial amount of the initiator is added by dropwise addition; the remaining amount of the monomer mixture is added by dropwise addition; the remaining amount of the initiator is added by dropwise addition.

The optional scheme is to optimize the proportioning of each component. In some specific schemes, the mass ratio of methyl methacrylate, n-butyl acrylate, hydroxypropyl acrylate, methacrylic acid and styrene is 45 :(16~9):4:5:2;

The quality of the 1,1,3,3-tetramethylperoxybutyl-2-ethylhexanoate is 1%-2% of n-butyl acrylate;

The quality of the dodecylphenol polyoxyethylene ether is 10%-15% of the quality of n-butyl acrylate; the allyloxy-2-hydroxypropane sulfonate sodium, allyloxy-fatty alcohol oxyethylene The mass of sodium ether sulfonate or disodium glycolate sulfinate is 8%-10% of the mass of n-butyl acrylate.

The invention also provides a preparation method of the random crack template. For this reason, the preparation method provided comprises that above-mentioned mask liquid is spin-coated on the surface of optical window glass substrate to form a mask layer, and then the optical glass window coated with the mask layer is placed in a temperature and humidity environment, and the surface mask layer generate random cracks.

An optional scheme is to optimize the spin-coating process conditions. In some specific schemes, the spin-coating process conditions are temperature 20-30°C, humidity 40%-45%, and spin-coating speed 600-800r/min .

An optional solution is to optimize the temperature and humidity environment. In some specific solutions, the humidity environment is: the temperature is set to 25-30° C., and the humidity is set to 40%-45%.

An optional solution is to optimize the thickness of the mask layer, and in some specific solutions, the thickness of the mask layer is 10-12 microns.

An optional solution is that the average width of the random cracks is less than or equal to 3mm; the crack void ratio is 10%-20%; the average grid size of the random cracks is 40-100mm.

The invention also provides a preparation method of the metal grid electromagnetic shielding optical window. For this reason, the preparation of the metal grid electromagnetic shielding optical window provided includes the preparation of a random crack template by the above method, and then plating metal in the random cracks on the surface of the random crack template, and then removing the mask to prepare the metal grid electromagnetic shielding optical window .

Optionally, the metal is selected from Cu, Ag, Au, Al or Ni.

The invention can solve the problem that mechanical processing cannot be realized and the problem of high cost of laser etching faced by the processing and manufacturing of the electromagnetic shielding optical window of the metal mesh grid with a width of less than 3 mm at present.

Description of drawings

Fig. 1 is a schematic flow chart of the method for preparing a random crack template.

Fig. 2 is a diagram of a random crack template prepared in Example 1 of the present invention.

Fig. 3 is a random crack template prepared in Example 2 of the present invention.

Fig. 4 is a random crack template prepared in Example 3 of the present invention.

Fig. 5 is a random crack template prepared in Example 4 of the present invention.

Fig. 6 is a diagram of the light transmittance of the quartz light window before and after plating the metal grid prepared in Example 5 of the present invention.

Fig. 7 is the test result of the electromagnetic shielding performance of the quartz light window prepared in Example 5 of the present invention.

Fig. 8 is the RW-116 type random crack mask prepared in Comparative Example 1.

Fig. 9 is the RW-116 type random crack mask prepared in Comparative Example 2.

Detailed ways

Unless otherwise specified, scientific and technical terms herein are to be understood according to the understanding of those of ordinary skill in the relevant art. It should be noted that, on the basis of the scheme of the present invention, those skilled in the art can understand the components involved in the method of the present invention, including but not limited to the components, the proportion of each component, temperature and duration, the order and method of adding components, and the mixing method. etc. carry out optimal selection to realize the effect of the present invention.

The optical window glass substrate described herein can be selected from substrates that meet the performance of optical fiber windows, such as but not limited to quartz glass, K9 glass, BK7 glass, fluorogallate glass, silicon single crystal, germanium single crystal, zinc sulfide/ Zinc selenide crystals, calcium fluoride crystals, etc. The following examples illustrate the present invention by taking quartz glass as an example.

The detection methods of the average width of cracks and the average size of grids (that is, the width of grids) described in the following examples are: after testing with an optical microscope, the crack width data (500 cracks/m ² ), The grid size data (500/m ² ) is statistically calculated and obtained after calculating the corresponding average value. The crack void ratio was calculated by Matlab software image recognition. The components used in the following examples are commercially available products.

Example 1:

The monomer mixture used in this embodiment, initiator and emulsifier are:

Monomer mix: 30.0 g methyl methacrylate (MMA), 10 g n-butyl acrylate (BA), 1.2 mL hydroxypropyl acrylate (HPA), 0.6 mL methacrylic acid (AA), and 0.6 mL phenylacetic acid (St) Stir and mix uniformly in a container to obtain a monomer mixture.

Initiator: 0.2g of 1,1,3,3-tetramethylperoxybutyl-2-ethylhexanoate (Trigonox421) and 20.0mL of ultrapure water were magnetically stirred to fully dissolve Trigonox421 to form an initiator.

Emulsifier: 0.8g sodium allyloxy-2-hydroxypropane sulfonate (AHPS), 1.2g dodecylphenol polyoxyethylene ether (OP-10) and 35.0mL ultrapure water were mixed by magnetic stirring to obtain emulsifier.

Preparation of monomer mixture, initiator and emulsifier mixture:

Add the above 10wt% monomer mixture dropwise into the container, then add 0.5g sodium bicarbonate to adjust the pH value to neutral, and stir with a magnetic stirrer until the solution becomes a milky mixture;

Heat the above milky mixture to 75°C, and slowly add 20wt% initiator solution dropwise while stirring; after the addition is completed, raise the heating temperature to 80°C and keep it for 30min; then continue to drop the remaining 90wt% monomer The initiator solution of mixture and 80wt%, and insulation 3h obtains monomer mixture, initiator and emulsifier mixed solution;

Continue to heat up the temperature of the monomer mixture, initiator and emulsifier mixture to 85°C and keep it for 2 hours, then cool it down to room temperature naturally, then add an appropriate amount of ammonia water to adjust the pH to neutral, and then use suction filtration, Buchner funnel equipped with 500 mesh Filter the mixed solution through a filter cloth for 3 times, and collect the filtrate to obtain a masking solution.

Further use a spin coater (KW-4T), set the speed at 800r/min, and spin-coat the masking solution prepared by the above scheme on the clean optical window quartz glass. The spin-coating time is 50s to obtain a mask layer with a thickness of about : 9-10mm;

）为2.6 mm，网格平均大小（/>

）为52.3mm的联通性良好的随机裂纹掩模板，裂纹空占比为：15%。Put the above-coated optical window glass covering the mask layer in a temperature and humidity chamber, set the temperature at 25°C, set the humidity at 45%, and control the time for 12 hours; the random cracks of the formed template are shown in Figure 2. The average crack width (

) is 2.6 mm, the average grid size (/>

) is a 52.3mm random crack mask with good connectivity, and the crack void ratio is 15%.

Example 2:

The difference between this example and Example 1 is that the monomer mixture used is: 40.0g methyl methacrylate (MMA), 10g n-butyl acrylate (BA), 1.6mL hydroxypropyl acrylate (HPA), 0.8ml formazan Acrylic acid (AA) and 0.8ml phenylacetic acid (St);

The random cracks of the template formed in this embodiment are shown in Figure 3. The average width of the cracks is 2.2 mm, and the average size of the grid is 42.9 mm. It is a random crack mask with good connectivity. The crack void ratio of this embodiment is: 13%.

Example 3:

The difference between this example and Example 1 is that the monomer mixture used is: 50.0g methyl methacrylate (MMA), 10g n-butyl acrylate (BA), 2.0mL hydroxypropyl acrylate (HPA), 1.0ml formazan Base acrylic acid (AA) and 1.0ml phenylacetic acid (St); the thickness of the mask layer in this embodiment is about: 8-9mm;

The random cracks of the template formed in this embodiment are shown in Figure 4, the average width of the cracks is 1.94mm, the average size of the grid is 38.5mm, and the random crack mask with good connectivity has a crack ratio of 10%. .

Example 4:

The difference between this embodiment and Embodiment 1 is that the template formation process is that the coated optical window glass covering the mask layer is placed in a temperature and humidity chamber, the temperature is set to 30 ° C, the humidity is set to 50%, and the time is controlled. for 12h;

The random cracks formed in the template are shown in Figure 5. The average width of the cracks is 2.4 mm, and the average size of the grid is 51.9 mm. The random crack mask with good connectivity has a crack void ratio of 14%.

Further, the existing metal plating method (such as ion source assisted evaporation method) can be used to plate metal in the random cracks on the prepared mask plate, and remove the mask layer (or mask plate) after metal plating to prepare a metal mesh The grid electromagnetically shields the optical window.

Example 5:

This example adopts ion source assisted evaporation method (ion source anode voltage 200V, anode current 1.5A, argon partial pressure 3.0×10 ^-3 Pa, argon flow rate 10sccm), using Example 1 (01#) and Example The 4 (04#) mask plates were respectively plated with random metal Cu grids to prepare random metal copper grids and make metal grid electromagnetic shielding optical windows.

Afterwards, a four-probe tester was used to test the sheet resistance of the optical window made in this embodiment. The sheet resistances of the sample in Example 1 and the sample in Example 4 were 4.69Ω/sq and 3.75Ω/sq respectively, compared with GB/T26598-2011 According to the relevant regulations in the above-mentioned embodiment, the metal lines of the grid on the surface of the samples obtained in the above examples have good connectivity.

The light transmittance of the sample was tested with an ultraviolet-visible spectrophotometer. As shown in Figure 6, the absolute transmittance in the visible light band is about 80%. Compared with the relevant regulations in GB/T26598-2011, the light transmittance performance is good.

Adopt flange coaxial method to test the electromagnetic shielding ability of this embodiment two samples simultaneously, as shown in Figure 7, test result shows, when electromagnetic wave frequency is 1-3GHz, electromagnetic shielding ability is 44dB on average; Electromagnetic wave frequency is 3 At -18GHz, the electromagnetic shielding performance is 50dB on average. Compared with the relevant regulations in GB/T35575-2017, the electromagnetic shielding performance of the obtained window is excellent.

Comparative example 1:

The difference between this comparative example and Example 1 is that the masking liquid is replaced by: the masking liquid made of acrylic emulsion; the commercially available acrylic emulsion (RW-116, Korea Hanwha Co. mesh filter cloth for 3 times, and the filtrate was collected to obtain the masking solution of the comparative example.

The random crack mask formed in this comparative example is shown in Figure 8. The crack width is uneven, the grid size varies greatly, and there are many semi-branch cracks, resulting in poor overall connectivity of the template.

Comparative example 2:

The difference between this comparative example and comparative example 1 is that the rotational speed during spin coating is set to 1000r/min;

The random crack mask formed in this comparative example is shown in Figure 9. The crack width is uneven, the grid size varies greatly, and there are many semi-branch cracks, resulting in poor overall connectivity of the template.

Table 1 Comparison of crack template performance parameters in the examples

As shown in Table 1, the uniformity and connectivity of random cracks prepared by the present invention are good (that is, the longer the crack shared by multiple grids, the better the connectivity, and vice versa).

Claims (8)

1. A masking liquid, characterized in that, the preparation method of said masking liquid comprises: cooling the mixed solution of monomer mixture, emulsifier and initiator at 80～85°C after being kept warm, and waiting to be cooled to room temperature Adjust the pH value to neutral, then filter with a 400-500 mesh filter cloth or membrane, and collect the filtrate as a masking solution; The monomer mixture is a mixture of methyl methacrylate, n-butyl acrylate, hydroxypropyl acrylate, methacrylic acid and styrene; The emulsifier is an aqueous solution of allyloxy-2-hydroxypropane sulfonate sodium and dodecylphenol polyoxyethylene ether, or an allyloxy-fatty alcohol oxyethylene ether sodium sulfonate and dodecylphenol An aqueous solution of phenol polyoxyethylene ether, or an aqueous solution of disodium glycolate sulfinate and dodecylphenol polyoxyethylene ether; The initiator is an aqueous solution of 1,1,3,3-tetramethylperoxybutyl-2-ethylhexanoate; The preparation method of the mixed solution of the monomer mixture, emulsifier and initiator comprises: after mixing the emulsifier and part of the monomer mixture, adjusting the pH value to neutral, mixing and heating to 70-75°C, and then Add a part amount of initiator, continue to heat up to 75-80°C and keep it warm, then add the remaining amount of monomer mixture and the remaining amount of initiator to mix and keep it warm; The partial amount of initiator is added by dropwise addition; the remaining amount of monomer mixture is added by dropwise addition; the remaining amount of initiator is added by dropwise addition; The mass ratio of described methyl methacrylate, n-butyl acrylate, hydroxypropyl acrylate, methacrylic acid and styrene is 45:(16～9):4:5:2; The quality of the 1,1,3,3-tetramethylperoxybutyl-2-ethylhexanoate is 1%-2% of n-butyl acrylate; The quality of the dodecylphenol polyoxyethylene ether is 10%-15% of the quality of n-butyl acrylate; the allyloxy-2-hydroxypropane sulfonate sodium, allyloxy-fatty alcohol oxyethylene The mass of sodium ether sulfonate or disodium glycolate sulfinate is 8%-10% of the mass of n-butyl acrylate. 2. a preparation method of random crack template, it is characterized in that, method comprises that the mask liquid described in claim 1 is spin-coated on optical window glass substrate surface to form mask layer, the optical glass that will be coated with mask layer afterwards The window is placed in a temperature and humidity environment, and random cracks are generated on the surface mask layer. 3. The method for preparing a random crack template according to claim 2, wherein the spin coating process conditions are temperature 20-30°C, humidity 40%-45%, and spin-coating speed 600-800r/min. 4. The method for preparing a random crack template according to claim 2, wherein the temperature and humidity environment is: the temperature is set at 25-30°C, and the humidity is set at 40%-45%. 5 . The method for preparing a random crack template according to claim 2 , wherein the thickness of the mask layer is 10-12 microns. 6. The preparation method of the random crack template according to claim 2, characterized in that, the average width of the random crack is less than or equal to 3 μm; the void ratio of the crack is: 10%-20%; the grid of the random crack Average size: 40-100 μm. 7. A method for preparing a metal grid electromagnetic shielding optical window, characterized in that, adopting the method described in any one of claims 2-6 to prepare a random crack template, and then plating metal in random cracks on the surface of the random crack template, Then the mask is removed to prepare the metal grid electromagnetic shielding optical window. 8. The method for preparing an electromagnetic shielding optical window with a metal grid according to claim 7, wherein the metal is selected from Cu, Ag, Au, Al or Ni.

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