Electromagnetic silver paste shielding film and preparation process

Abstract

The present invention discloses an electromagnetic silver paste shielding film and a preparation process, comprising: a first release protective film, an insulating layer, a shielding layer, a conductive layer and a second release protective film which are stacked in sequence; the raw materials for preparing the insulating layer include: 15-40 parts of rubber, 10-15 parts of flame retardant, 2-5 parts of curing agent, 0.05-0.1 parts of ion capture agent, 0.1-0.5 parts of antioxidant, 0.1-0.5 parts of accelerator, 15-45 parts of resin, 10-40 parts of dye agent, and 10-40 parts of diluent. By improving the raw materials of the insulating layer and the proportion of each raw material, as well as improving the coating adhesive process, the electromagnetic shielding film can be improved in terms of bending resistance, wear resistance, high reflectivity and other properties, so that the electronic products using the electromagnetic silver paste shielding film can realize high-frequency transmission of signals and have good shielding function.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic shielding materials, and more specifically, to an electromagnetic silver paste shielding film and a preparation process thereof. Background Art

[0002] Electromagnetic waves are the main way of electromagnetic energy propagation. When high-frequency circuits are working, they will radiate electromagnetic waves outward, causing interference to other nearby devices. On the other hand, various electromagnetic waves in space will also be induced into the circuit and cause interference to the circuit. The role of electromagnetic shielding is to cut off the propagation path of electromagnetic waves, thereby eliminating interference. Among the many means of solving electromagnetic interference problems, electromagnetic shielding is the most basic and effective. The biggest advantage of using electromagnetic shielding to solve electromagnetic interference problems is that it will not affect the normal operation of the circuit, so there is no need to make any modifications to the circuit.

[0003] At present, electromagnetic shielding films are used in 5G communications, automotive electronics and other industries. Under the 5G environment, the high-frequency and high-speed trend of electronic products represented by smart phones is becoming more and more obvious. The use of FPC in its internal structure is increasing to improve the internal assembly density. At the same time, the electromagnetic interference between electronic components is becoming more and more serious, which objectively increases the demand for electromagnetic shielding films. On the one hand, this demand is reflected in the increase in the use of electromagnetic shielding films, and on the other hand, it is reflected in the requirements for improving the performance of electromagnetic shielding films, such as thinner thickness, higher shielding efficiency, lower insertion loss, stronger bending resistance, stronger tearing resistance, etc., to achieve high-frequency transmission of signals and have good shielding function.

[0004] The present invention is dedicated to proposing an electromagnetic silver paste shielding film and a preparation process to improve the bending resistance, wear resistance, high reflectivity and other properties of the electromagnetic shielding film, so as to at least partially solve the problems existing in the prior art. Summary of the invention

[0005] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0006] In order to at least partially solve the above problems, the present invention provides an electromagnetic silver paste shielding film, comprising: a first release protective film, an insulating layer, a shielding layer, a conductive layer and a second release protective film which are sequentially stacked;

[0007] The raw materials for preparing the insulating layer include: 15-40 parts of rubber, 10-15 parts of flame retardant, 2-5 parts of curing agent, 0.05-0.1 parts of ion capture agent, 0.1-0.5 parts of antioxidant, 0.1-0.5 parts of accelerator, 15-45 parts of resin, 10-40 parts of dye, and 10-40 parts of diluent.

[0008] Preferably, the material of the shielding layer is one or more of nickel-silver alloy, nickel-gold alloy, titanium-silver alloy, titanium-gold alloy, chromium-silver alloy and chromium-gold alloy.

[0009] Preferably, the conductive layer is made of thermosetting conductive adhesive.

[0010] Preferably, the shielding layer has a thickness of 0.1-5 microns, the conductive layer has a thickness of 3-30 microns, and the insulating layer has a thickness of 3-10 microns.

[0011] Preferably, the color of the dye is one of white, green, blue, silvery white, gray and red.

[0012] Preferably, the inorganic pigment powder is titanium dioxide.

[0013] Preferably, the particle size of the conductive powder in the conductive adhesive is 1-15 microns.

[0014] The present invention also provides a process for preparing an electromagnetic silver paste shielding film, comprising:

[0015] S100, preparing semi-finished products required for adhesive, mixing the semi-finished products, dispersing them using a high-speed disperser, and then filtering them to obtain an adhesive;

[0016] The dispersion time is 3-10h, the rotation speed is 800-1200r / min, and the dispersion temperature is maintained at 25-30℃.

[0017] S200, applying adhesive on the first release protective film and baking it to form an insulating layer with a thickness of 3-10 microns;

[0018] The baking tunnel is provided with six temperature sections, which are 60°C, 80°C, 120°C, 160°C, 160°C, and 60°C.

[0019] S300, forming a shielding layer with a thickness of 0.1-5 microns on the insulating layer by sputtering electroplating;

[0020] S400, coating the shielding layer with a conductive adhesive to form a conductive layer with a thickness of 3-30 microns;

[0021] S500, laying a second release protective film on the conductive layer.

[0022] Preferably, the semi-finished products required for the adhesive include:

[0023] Semi-finished product 1, 15-35 parts rubber, 65-85 parts diluent;

[0024] Semi-finished product 2, 10-30 parts of semi-finished product 1, 20-30 parts of flame retardant, 30-70 parts of diluent;

[0025] Semi-finished product three, 20-50 parts of curing agent, 50-80 parts of diluent;

[0026] Semi-finished product 4, 10-20 parts of semi-finished product 1, 40-60 parts of ion capture agent, 20-50 parts of diluent;

[0027] Semi-finished product five, 20-40 parts of antioxidant, 60-80 parts of diluent;

[0028] Semi-finished product six, 20-30 parts of accelerator, 70-80 parts of diluent;

[0029] Semi-finished product seven, 40-60 parts of resin, 40-60 parts of diluent;

[0030] Semi-finished product eight, 20-50 parts of inorganic pigment powder, 50-80 parts of diluent.

[0031] Preferably, in said S200, the coating device used for coating the adhesive comprises: a material box for containing the adhesive; a coating roller rotatably connected above the material box and used for coating the adhesive in the material box on the first release protective film; a defoaming box for pre-defoaming the adhesive delivered to the material box;

[0032] The top of the material box is provided with an opening corresponding to the coating roller, a baffle in contact with the coating roller is provided on one side of the opening, and a first scraper in contact with the coating roller is provided on the other side of the opening; a second scraper in contact with the coating roller is provided below the first scraper, and the second scraper divides the material box into a first chamber for accommodating the coating roller and a second chamber for containing scraped residual material;

[0033] The second scraper, the first scraper and the baffle are arranged in sequence along the rotation direction of the coating roller;

[0034] The first scraper is arranged along the tangential direction of the coating roller.

[0035] Preferably, the defoaming box comprises: a box body, a third chamber is provided in the box body; a rubber guide tube is arranged at the top of the box body, and a first circular hole connected to the rubber guide tube is provided at the top of the third chamber; a driving part is provided at the top of the rubber guide tube, and a rotating rod is provided at the output end of the driving part, and a spiral blade is provided on the outer surface of the rotating rod located at the first circular hole, and the bottom end of the spiral blade extends out of the first circular hole; a rubber inlet tube is connected to the rubber guide tube; a first flow channel is provided in the box body and is spaced apart from the third chamber, and the bottom end of the first flow channel is connected to the third chamber; a fourth chamber connected to the first flow channel is provided at the top of the first flow channel, and one side of the top of the fourth chamber is connected to the first circular hole through the second flow channel; a plurality of vertically arranged partitions are provided in the fourth chamber, and a through hole connected to the vacuum chamber is provided at the top of the fourth chamber; a first liquid level sensor is provided in the third chamber, and a second liquid level sensor is provided in the fourth chamber.

[0036] A material delivery pipe connected to the material box is provided at the bottom end of one side of the box body, a first valve is provided on the material delivery pipe, a second valve is provided on the glue feed pipe, and the other end of the glue feed pipe is connected to the glue storage barrel.

[0037] An overflow pipe is provided on the top of the material box, and a return pipe is provided in communication with the second chamber. Both the overflow pipe and the return pipe are in communication with a recovery bucket.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] The electromagnetic silver paste shielding film and preparation process described in the present invention can enhance the bending resistance, wear resistance, high reflectivity and other properties of the electromagnetic shielding film by improving the raw materials of the insulating layer and the ratio of each raw material, as well as improving the adhesive coating process, so that electronic products using the electromagnetic silver paste shielding film can achieve high-frequency signal transmission and have good shielding function.

[0040] The electromagnetic silver paste shielding film and preparation process described in the present invention, and other advantages, objectives and features of the present invention will be partially reflected through the following description, and will also be partially understood by technicians in this field through research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 It is a schematic structural diagram of the electromagnetic silver paste shielding film of the present invention;

[0043] Figure 2 It is a structural schematic diagram of a coating device in the preparation process of the electromagnetic silver paste shielding film described in the present invention;

[0044] Figure 3 It is a schematic structural diagram of a material box in the preparation process of the electromagnetic silver paste shielding film of the present invention;

[0045] Figure 4 It is a structural schematic diagram of a material box and a defoaming box in the preparation process of the electromagnetic silver paste shielding film of the present invention;

[0046] Figure 5 It is a structural schematic diagram of a defoaming box in the preparation process of the electromagnetic silver paste shielding film described in the present invention. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments so that those skilled in the art can implement the invention with reference to the description.

[0048] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0049] like Figure 1 As shown, the present invention provides an electromagnetic silver paste shielding film, comprising: a first release protective film 1, an insulating layer 2, a shielding layer 3, a conductive layer 4 and a second release protective film 5 which are sequentially stacked;

[0050] The raw materials for preparing the insulating layer 2 include: 15-40 parts of rubber, 10-15 parts of flame retardant, 2-5 parts of curing agent, 0.05-0.1 parts of ion capture agent, 0.1-0.5 parts of antioxidant, 0.1-0.5 parts of accelerator, 15-45 parts of resin, 10-40 parts of dye, and 10-40 parts of diluent.

[0051] The color of the dye is one of white, green, blue, silvery white, gray and red.

[0052] Working principle and beneficial effects of the above technical solution: In the prior art, black glue is usually coated on the surface of the first release protective film 1 to form a black insulating layer, while in the present invention, the dye can be one of white, green, blue, silver, gray, and red, but is not limited to the above colors;

[0053] In this embodiment, the dye is preferably white, and the above-mentioned raw materials are used to prepare the adhesive, and then the adhesive is coated on the surface of the first release protective film 1 to form a white insulating layer 2;

[0054] The insulating layer 2 of the present invention is prepared by three raw material ratios according to its achieved performance; they are: white high bending is a shielding film prepared by the insulating layer 2 using the raw materials prepared by the first ratio; white wear-resistant is a shielding film prepared by the insulating layer 2 using the raw materials prepared by the second ratio; white reflective is a shielding film prepared by the insulating layer 2 using the raw materials prepared by the second ratio; the three ratios of the raw materials for preparing the insulating layer 2 are shown in the following table:

[0055] NO. raw material White high bend White wear-resistant White reflective 1 rubber 15 servings 20 servings 15 servings 2 Flame retardants 15 servings 15 servings 15 servings 3 Curing agent 2 servings 2 servings 3 servings 4 Ion Scavenger 0.1 part 0.1 part 0.1 part 5 Antioxidants 0.1 part 0.1 part 0.1 part 6 Accelerator 0.1 part 0.5 serving 0.1 part 7 Resin 1 30 servings 15 servings 10 servings 8 Resin II 15 servings 20 servings 20 servings 9 Dyes 10 servings 10 servings 20 servings 10 Thinner 12.7 servings 17.3 servings 16.7 servings

[0056] In the above table, resin 1 and resin 2 use different types of resins. Resin 1 can use 901 resin, and resin 2 can use 128 resin. 901 resin has high cross-linking density and strong adhesion. 128 resin can be hardened at room temperature or higher temperature. Appropriately adjusting the ratio of the two can improve the relevant properties of the insulating layer 2.

[0057] The following table compares the performance of shielding films using the prior art black insulating layer and shielding films prepared using the above three ratios of white insulating layer:

[0058] Comparison of various formulas of white insulating glue

[0059]

[0060] From the above comparison, it can be seen that the shielding film prepared by the first ratio method has no weakening in other properties compared with the shielding film of the prior art, while the bending performance is significantly improved;

[0061] Compared with the shielding film of the prior art, the shielding film prepared by the second ratio method has no weakening in other properties, but has significantly increased hardness, thereby improving the wear resistance of the shielding film;

[0062] Compared with the shielding film of the prior art, the shielding film prepared by the third ratio has no weakening in other properties, and the reflective effect reaches 85%, and the reflective performance is greatly improved.

[0063] The shielding film prepared by the present invention can further improve the signal transmission capability and shielding performance of electronic products.

[0064] In one embodiment, the material of the shielding layer 3 is selected from one of nickel-silver alloy, nickel-gold alloy, titanium-silver alloy, titanium-gold alloy, chromium-silver alloy and chromium-gold alloy.

[0065] The working principle and beneficial effects of the above technical solution: the shielding layer 3 is formed by a sputtering electroplating process, and the material used for the shielding layer 3 is not limited to the above types, but may also be other alloys containing silver or gold.

[0066] In one embodiment, the conductive layer 4 is made of thermosetting conductive adhesive.

[0067] The particle size of the conductive powder in the conductive adhesive is 1-15 microns.

[0068] The working principle and beneficial effects of the above technical solution: the conductive adhesive is mainly composed of a resin matrix, conductive particles and dispersing additives, auxiliary agents, etc.; in this embodiment, the conductive powder is formed by gold or silver immersion on the surface of alloy powder copper or nickel, and the shape of the conductive powder is one of dendrites, dendrite mixed particles, chain particles, chain mixed particles, etc.

[0069] In one embodiment, the shielding layer 3 has a thickness of 0.1-5 microns, the conductive layer 4 has a thickness of 3-30 microns, and the insulating layer 2 has a thickness of 3-10 microns.

[0070] The working principle and beneficial effects of the above technical solution: the thickness of the shielding film is reduced as much as possible, and a micro-concave coating process can be used when coating the conductive glue to form the conductive layer 4, and when coating the adhesive to form the insulating layer 2. The coating thickness can be accurately controlled, making the coating more uniform, improving the coating quality, and further improving the performance of the finished shielding film.

[0071] like Figure 2-5 As shown, the present invention also provides a preparation process of an electromagnetic silver paste shielding film, comprising:

[0072] S100, preparing semi-finished products required for adhesive, mixing the semi-finished products, dispersing them using a high-speed disperser, and then filtering them to obtain an adhesive;

[0073] The dispersion time is 3-10h, the rotation speed is 800-1200r / min, and the dispersion temperature is maintained at 25-30℃. In order to avoid excessive temperature during the dispersion process, a constant temperature water tank is added to maintain the temperature at 25-30℃. After the dispersion is completed, a 5-10 micron filter is used to filter to obtain the adhesive;

[0074] S200, applying adhesive on the first release protective film 1, and baking to form an insulating layer 2 with a thickness of 3-10 microns;

[0075] The baking tunnel is provided with six temperature sections, which are 60°C, 80°C, 120°C, 160°C, 160°C, and 60°C.

[0076] S300, forming a shielding layer 3 with a thickness of 0.1-5 microns on the insulating layer 2 by sputtering electroplating;

[0077] S400, coating the shielding layer 3 with a conductive adhesive to form a conductive layer 4 with a thickness of 3-30 microns;

[0078] S500 , laying a second release protective film 5 on the conductive layer 4 .

[0079] Wherein, the semi-finished products required for the adhesive include:

[0080] Semi-finished product 1, 15-35 parts rubber, 65-85 parts diluent;

[0081] Semi-finished product 2, 10-30 parts of semi-finished product 1, 20-30 parts of flame retardant, 30-70 parts of diluent;

[0082] Semi-finished product three, 20-50 parts of curing agent, 50-80 parts of diluent;

[0083] Semi-finished product 4, 10-20 parts of semi-finished product 1, 40-60 parts of ion capture agent, 20-50 parts of diluent;

[0084] Semi-finished product five, 20-40 parts of antioxidant, 60-80 parts of diluent;

[0085] Semi-finished product six, 20-30 parts of accelerator, 70-80 parts of diluent;

[0086] Semi-finished product seven, 40-60 parts of resin, 40-60 parts of diluent;

[0087] Semi-finished product eight, 20-50 parts of inorganic pigment powder, 50-80 parts of diluent.

[0088] The inorganic pigment powder is preferably titanium dioxide.

[0089] The working principle and beneficial effects of the above technical solution are as follows: the rubber is selected from nitrile rubber N23 or epoxy resin E20, the diluent is selected from mek or mcs, the flame retardant is selected from OP935 or A42M or 101HRT, the ion scavenger is selected from IXE-100, the curing agent is selected from DDS, and the resin is selected from 901 or 128;

[0090] The inorganic pigment powder in the dye agent is selected from titanium dioxide, chrome yellow, iron blue, cadmium red, cadmium yellow, lead powder, carbon black, iron oxide red, iron oxide yellow and the like to meet different color requirements. Titanium dioxide is preferred because it has good reflective properties and is more beautiful.

[0091] Before preparing the adhesive, it is preferred to prepare semi-finished products of each component of the adhesive separately, and then all the semi-finished products are mixed in proportion. The mixing ratio of each semi-finished product can be 20-40 parts of semi-finished product one, 10-15 parts of semi-finished product two, 3-5 parts of semi-finished product three, 0.05-0.1% of semi-finished product four, 0.1-0.5 parts of semi-finished product five, 0.1-0.5 parts of semi-finished product six, 15-30 parts of semi-finished product seven, and 20-40 parts of semi-finished product seven. The mixing ratio is not limited to the above, and can be adjusted and configured according to needs;

[0092] After mixing the components in proportion, use a high-speed disperser to disperse them. The disperser is a high-speed agitator that can form strong turbulence locally, fully disperse and crush the mixed raw materials, have a strong dispersing and emulsifying effect, and can obtain adhesives with smaller particle sizes;

[0093] After dispersion is completed, the adhesive is filtered through a 5-10 micron filter to obtain an adhesive with a small particle size and good consistency;

[0094] The prepared adhesive is coated on the first release protective film 1 by a coating device, and then baked. The baking adopts a drying oven. The temperature of the drying oven is divided into six sections, which are 60°C, 80°C, 120°C, 160°C, 160°C, and 60°C in order, so that the adhesive is firmly combined with the first release protective film 1 to form an insulating layer 2. When coating, attention should be paid to the uniformity of coating and the defects generated on the coating surface, which will directly affect the performance of the shielding film;

[0095] The atoms of the metal target are blasted out by sputtering electroplating and deposited on the surface of the insulating layer 2 to form a coating, which is the shielding layer 3. Then, a conductive glue is coated on the surface of the shielding layer 3 to form a conductive layer 4. Finally, a second release protective film 5 is laid on the conductive layer 4.

[0096] The first release protective film 1 mainly plays a bearing role for coating, and the second release protective film 5 is mainly used to protect the conductive layer 4. When using the shielding film, it is necessary to tear off the first release protective film 1 and the second release protective film 5, and use the conductive layer 4 to stick on electronic devices such as flexible circuit boards to achieve good shielding function.

[0097] In one embodiment, in S200, after applying the adhesive on the first release protective film 1 and before baking, the process further includes detecting the uniformity of the adhesive applied on the surface of the first release protective film 1; the specific detection method is:

[0098] S210, obtaining a detection image of the adhesive coated on the surface of the first release protective film 1;

[0099] S220, dividing the detection image into at least four image detection areas;

[0100] S230, the coating uniformity in the image detection area is detected by the following formula:

[0101]

[0102] in, is the coating uniformity, A and B represent the grayscale values ​​of two pixels respectively, D represents the step size, W represents the direction, and its value is 0°, 45°, 90°, 135°, f(A, B; D, W) represents the value frequency of the grayscale value (A, B) of two pixels with a distance of D in the W direction;

[0103] S240: Determine the coating uniformity of each image detection area Whether the uniformity judgment threshold is met, if all are met, it indicates that the uniformity of the adhesive coated on the surface of the first release protective film 1 meets the standard, if at least one is not met, it indicates that the uniformity of the adhesive coated on the surface of the first release protective film 1 does not meet the standard, and the coating device needs to be adjusted.

[0104] Working principle and beneficial effects of the above technical solution: The detection of coating uniformity in step S230 is actually based on the detection of texture after the detection image is partitioned. If the coating is uneven, the texture will have defects, such as vertical bars, horizontal bars, etc. The above method is to calculate the grayscale relationship frequency of two pixels with a certain position relationship in the image detection area, and then detect the arrangement information of the texture in the image detection area in terms of interval, direction, change speed and change amplitude. In this embodiment, based on this principle, only the uniformity after coating is detected, so as to know whether there is an abnormality in the scraper or coating roller of the coating device, which affects the uniformity of coating, thereby ensuring the stability of the coating process;

[0105] In the above method, the detection image is divided into multiple detection areas for separate detection, which can improve the detection accuracy of uniformity and ensure the accuracy of the detection result.

[0106] In one embodiment, in the S200, the coating device used for coating the adhesive includes: a material box 6 for containing the adhesive; a coating roller 7 rotatably connected above the material box 6, for coating the adhesive in the material box 6 on the first release protective film 1; a defoaming box 8, for pre-defoaming the adhesive delivered to the material box 6;

[0107] The top of the material box 6 is provided with an opening 610 corresponding to the coating roller 7, a baffle 620 in contact with the coating roller 7 is provided on one side of the opening 610, and a first scraper 630 in contact with the coating roller 7 is provided on the other side of the opening 610; a second scraper 640 in contact with the coating roller 7 is provided below the first scraper 630, and the second scraper 640 divides the material box 6 into a first chamber 650 for accommodating the coating roller 7 and a second chamber 660 for containing scraped residual materials;

[0108] The second scraper 640, the first scraper 630 and the baffle 620 are arranged in sequence along the rotation direction of the coating roller 7;

[0109] The first scraper 630 is arranged along the tangential direction of the coating roller 7 .

[0110] The baffle 620 and the second scraper 640 are used to close the opening 610 of the material box 6 .

[0111] The working principle and beneficial effects of the above technical solution are as follows: a plurality of micro-concave holes are evenly arranged on the surface of the coating roller 7, a part of the coating roller 7 is immersed in the first chamber 650 of the material box 6, and as the coating roller 7 rotates, the adhesive is applied through the plurality of micro-concave holes, and then the adhesive on the surface of the coating roller 7 is scraped flat and quantitatively by the second scraper 640 and the first scraper 630, and the adhesive is evenly applied on the first release protective film 1, the direction of rotation of the coating roller 7 is opposite to the conveying direction of the first release protective film 1, and the adhesive is applied evenly by the tangential force of the contact between the two, so as to achieve uniform thin layer coating;

[0112] The second scraper 640, the first scraper 630 and the baffle 620 all lightly touch the coating roller 7, and wear is small. The baffle 620 can also be a scraper, mainly to close the opening 610 of the material box 6 together with the second scraper 640 to reduce the contact between the adhesive in the material box 6 and the air;

[0113] Since the wear of the scraper may cause uneven coating or make the coating thickness difficult to control, the first scraper 630 is set to have the same tangent direction as the coating roller 7. When the coating roller 7 rotates, the first scraper 630 is subjected to the least force relative to the coating roller 7 or is in a state of being free of force, which can reduce the wear of the scraper; and the second scraper 640 may also be set to have the same tangent direction as the coating roller 7, or be close to the tangent angle of the coating roller 7, which is also for the purpose of reducing the wear of the scraper; setting two scrapers can also ensure that when the second scraper 640 is worn, it can be remedied by the first scraper 630, thereby improving the stability of coating and reducing the frequency of scraper replacement;

[0114] Since gas may be mixed into the adhesive to form bubbles, the coating roller 7 may carry gas when applying the adhesive, resulting in vertical stripes of the adhesive applied on the first release protective film 1, which may also cause uneven coating, ultimately affecting the performance of the shielding film and resulting in defective products.

[0115] Therefore, in order to avoid bubbles being carried by the coating roller 7 when applying glue, the adhesive is defoamed before entering the material box 6 to ensure the coating quality, and the probability of the material box 6 itself coming into contact with the air is small, thereby further reducing the possibility of bubbles being carried by the coating roller 7 when applying glue.

[0116] In one embodiment, the defoaming box 8 includes: a box body 810, wherein a third chamber 811 is provided in the box body 810; a rubber guide tube 820 is arranged at the top of the box body 810, and a first circular hole 812 connected to the rubber guide tube 820 is provided at the top of the third chamber 811; a driving part 830 is provided at the top of the rubber guide tube 820, and a rotating rod 840 is provided at the output end of the driving part 830, and a spiral blade 850 is provided on the outer surface of the rotating rod 840 located at the first circular hole 812, and the bottom end of the spiral blade 850 extends out of the first circular hole 812; a rubber inlet tube 860 is connected to the rubber guide tube 820; the box body A first flow channel 813 is provided in 810, which is spaced apart from the third chamber 811, and the bottom end of the first flow channel 813 is connected to the third chamber 811; a fourth chamber 814 is provided at the top of the first flow channel 813 and is connected thereto, and one side of the top of the fourth chamber 814 is connected to the first circular hole 812 through a second flow channel 815; a plurality of vertically arranged partitions 870 are provided in the fourth chamber 814, and a through hole 816 connected to the vacuum chamber is provided at the top of the fourth chamber 814; a first liquid level sensor 880 is provided in the third chamber 811, and a second liquid level sensor 890 is provided in the fourth chamber 814.

[0117] A feed pipe 9 connected to the material box 6 is provided at the bottom of one side of the box body 810, and a first valve 10 is provided on the feed pipe 9. A second valve 11 is provided on the glue feed pipe 860, and the other end of the glue feed pipe 860 is connected to the glue storage barrel.

[0118] An overflow pipe 12 is provided at the top of the material box 6, and a return pipe 13 is provided in communication with the second chamber 660. Both the overflow pipe 12 and the return pipe 13 are communicated with a recovery bucket for reusing the residual material.

[0119] The working principle and beneficial effects of the above technical solution are as follows: the adhesive in the adhesive storage barrel is first transported to the adhesive guide tube 820 through the adhesive inlet tube 860, and the driving unit 830 drives the rotating rod 840 and the spiral blade 850 to rotate simultaneously. The outer peripheral surface of the spiral blade 850 is relatively sharp, and the gap with the inner peripheral wall of the first circular hole 812 is relatively small. Under the rotation of the spiral blade 850, the adhesive is transported by the spiral blade 850, and rotates and sprinkles into the third chamber 811 from the small gap formed by the spiral blade 850 and the first circular hole 812, and the spiral blade 850 also grinds the adhesive, shredding the larger particles in the adhesive, and can also shred the bubbles contained in the adhesive; when the adhesive is sprinkled into the third chamber 811, it collides with the side wall of the third chamber 811, further breaking the bubbles contained therein, and a plurality of spikes can be provided on the inner wall of the third chamber 811 to further improve the bubble breaking efficiency;

[0120] The gas generated by the bubble shattering will enter the fourth chamber 814 from the first flow channel 813, and then be pumped away through the vacuum environment or low-pressure environment of the pumping cavity (the pumping cavity mainly forms and maintains a vacuum environment or a low-pressure environment in the cavity through the pumping power unit, which is used to pump out the bubbles but not the adhesive); when the adhesive in the third chamber 811 increases, the adhesive will enter the fourth chamber 814 from the first flow channel 813, and the fourth chamber 814 is connected to the pumping cavity through the through hole 816, so the bubbles mixed in the adhesive in the fourth chamber 814 are extracted in the vacuum environment of the pumping cavity, and the bubbles are broken, and the broken bubbles form gas and are pumped away, thereby achieving defoaming treatment of the adhesive; the partition 870 arranged in the fourth chamber 814 can increase the contact area between the adhesive and the pumping cavity, thereby improving the defoaming effect;

[0121] When the adhesive in the third chamber 811 continues to increase, the second liquid level sensor 890 in the fourth chamber 814 detects that the adhesive has reached the first preset height, and the control unit closes the second valve 11 on the adhesive inlet pipe 860. At this time, the adhesive in the fourth chamber 814 enters the first circular hole 812 through the second flow channel 815, and the adhesive in the second flow channel 815 is transported downward to the third chamber 811 through the rotating spiral blade 850. The adhesive is then stored in the third chamber 811, the first flow channel 813, the fourth chamber 814, and the fourth chamber 814. A circulating flow is formed in the second flow channel 815. During the flow process, as long as there are bubbles in the adhesive that circulates into the fourth chamber 814, the bubbles will be sucked away through the exhaust cavity. In the case of the circulating flow, the adhesive distributed in various places of the third chamber 811 can have a chance to flow into the fourth chamber 814 for defoaming. In the case of the circulating flow, the bubbles hitting the spikes on the inner wall of the third chamber 811 can further play a defoaming role; thereby, the bubbles in the adhesive are completely eliminated.

[0122] When the defoaming treatment time reaches the preset time, the control unit stops the driving unit 830 and the air extraction power unit of the air extraction chamber, and opens the first valve 10 on the feed pipe 9, so that the adhesive flows from the lowest position of the third chamber 811 through the feed pipe 9 to the first chamber 650 of the material box 6. As the adhesive in the material box 6 decreases, the adhesive in the third chamber 811 will be transported to the first chamber 650 of the material box 6; since the adhesive is transported from the lowest position of the third chamber 811, air will not be mixed into the adhesive again, and a first liquid level sensor 880 is also provided in the third chamber 811. When the adhesive reaches the second preset height (the second preset height is not lower than the height at which the third chamber 811 is connected to the feed pipe 9), the adhesive is stopped from being transported, and the gluing can be stopped at the same time to avoid air mixing, and the above-mentioned glue feeding and defoaming steps are repeated at the same time to fill the third chamber 811 with adhesive, and the defoaming and glue filling process into the material box 6 is realized in this cycle.

[0123] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0124] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0125] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A process for preparing an electromagnetic silver paste shielding film, characterized in that: The electromagnetic silver paste shielding film comprises a first release protective film (1), an insulating layer (2), a shielding layer (3), a conductive layer (4) and a second release protective film (5) which are sequentially stacked; The raw materials for preparing the insulating layer (2) include: 15-40 parts of rubber, 10-15 parts of flame retardant, 2-5 parts of curing agent, 0.05-0.1 parts of ion capture agent, 0.1-0.5 parts of antioxidant, 0.1-0.5 parts of accelerator, 15-45 parts of resin, 10-40 parts of dye, and 10-40 parts of diluent; The preparation process of the electromagnetic silver paste shielding film includes the following steps: S100, preparing semi-finished products required for adhesive, mixing the semi-finished products, dispersing them using a high-speed disperser, and then filtering them to obtain an adhesive; S200, applying adhesive on the first release protective film and baking it to form an insulating layer with a thickness of 3-10 microns; S300, forming a shielding layer with a thickness of 0.1-5 microns on the insulating layer by sputtering electroplating; S400, coating the shielding layer with a conductive adhesive to form a conductive layer with a thickness of 3-30 microns; S500, laying a second release protective film on the conductive layer; In the S200, the coating device used for coating the adhesive includes: a material box for containing the adhesive; a coating roller rotatably connected above the material box and used to coat the adhesive in the material box on the first release protective film; a defoaming box for pre-defoaming the adhesive delivered to the material box; The top of the material box is provided with an opening corresponding to the coating roller, a baffle in contact with the coating roller is provided on one side of the opening, and a first scraper in contact with the coating roller is provided on the other side of the opening; a second scraper in contact with the coating roller is provided below the first scraper, and the second scraper divides the material box into a first chamber for accommodating the coating roller and a second chamber for containing scraped residual material; The second scraper, the first scraper and the baffle are arranged in sequence along the rotation direction of the coating roller; The first scraper is arranged along the tangent direction of the coating roller; Wherein, the defoaming box comprises: a box body, a third chamber is arranged in the box body; a rubber guide tube is arranged at the top of the box body, and a first circular hole connected to the rubber guide tube is arranged at the top of the third chamber; a driving part is arranged at the top of the rubber guide tube, and a rotating rod is arranged at the output end of the driving part, and a spiral blade is arranged on the outer surface of the rotating rod located at the first circular hole part, and the bottom end of the spiral blade extends out of the first circular hole; a rubber inlet tube is connected to the rubber guide tube; a first flow channel is arranged in the box body and is spaced apart from the third chamber, and the bottom end of the first flow channel is connected to the third chamber; a fourth chamber connected to the first flow channel is arranged at the top of the first flow channel, and one side of the top of the fourth chamber is connected to the first circular hole through the second flow channel; a plurality of vertically arranged partitions are arranged in the fourth chamber, and a through hole connected to the vacuum chamber is arranged at the top of the fourth chamber; a first liquid level sensor is arranged in the third chamber, and a second liquid level sensor is arranged in the fourth chamber.

2. The preparation process of the electromagnetic silver paste shielding film according to claim 1, characterized in that: The material of the shielding layer (3) is selected from one of nickel-silver alloy, nickel-gold alloy, titanium-silver alloy, titanium-gold alloy, chromium-silver alloy and chromium-gold alloy.

3. The preparation process of the electromagnetic silver paste shielding film according to claim 1, characterized in that: The material of the conductive layer (4) is thermosetting conductive adhesive.

4. The preparation process of the electromagnetic silver paste shielding film according to claim 1, characterized in that: The thickness of the shielding layer (3) is 0.1-5 microns, the thickness of the conductive layer (4) is 3-30 microns, and the thickness of the insulating layer (2) is 3-10 microns.

5. The preparation process of the electromagnetic silver paste shielding film according to claim 1, characterized in that: The color of the dye is one of white, green, blue, silvery white, gray and red.

6. The preparation process of the electromagnetic silver paste shielding film according to claim 3, characterized in that: The particle size of the conductive powder in the conductive adhesive is 1-15 microns.

7. The preparation process of the electromagnetic silver paste shielding film according to claim 1, characterized in that: The semi-finished products required for the adhesive include: Semi-finished product 1, 15-35 parts rubber, 65-85 parts diluent; Semi-finished product 2, 10-30 parts of semi-finished product 1, 20-30 parts of flame retardant, 30-70 parts of diluent; Semi-finished product three, 20-50 parts of curing agent, 50-80 parts of diluent; Semi-finished product 4, 10-20 parts of semi-finished product 1, 40-60 parts of ion capture agent, 20-50 parts of diluent; Semi-finished product five, 20-40 parts of antioxidant, 60-80 parts of diluent; Semi-finished product six, 20-30 parts of accelerator, 70-80 parts of diluent; Semi-finished product seven, 40-60 parts of resin, 40-60 parts of diluent; Semi-finished product eight, 20-50 parts of inorganic pigment powder, 50-80 parts of diluent.

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