Flame-retardant heat-conducting organic silicon pouring sealant and preparation method thereof

Abstract

The invention discloses a flame-retardant heat-conducting organic silicon pouring sealant and a preparation method thereof, and relates to the technical field of pouring sealants, the flame-retardant heat-conducting organic silicon pouring sealant comprises a resin main body and a hardening composition which are matched with each other, the resin main body at least comprises a base adhesive, a flame retardant and a heat-conducting filler, and the hardening composition comprises a marginal hardening agent and an internal curing agent. The acid ester content of the marginal hardening agent is larger than that of the internal curing agent, and a first mixture formed by the marginal hardening agent and the resin body is used for making contact with the potting side boundary and surrounding a second mixture formed by the internal curing agent and the resin body. According to the invention, the potting effect of the organic silicon potting adhesive can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of potting adhesives, and in particular to a flame retardant and thermally conductive organic silicone potting adhesive and a preparation method thereof. Background Art

[0002] There are a variety of electronic components in electronic products, many of which are integrated on circuit boards. During the use of electronic products, electronic components generate heat, and the product structure is generally equipped with heat dissipation holes to discharge the heat. Although the existence of heat dissipation holes allows the product to cool down faster and the temperature is not too high, it is also connected to the atmospheric environment, which makes it easy for dust in the environment to enter the product and cause circuit board failures.

[0003] In response to the above problems, some manufacturers inject silicone potting glue into the area where the product's circuit board is located. On the one hand, it blocks the erosion of the external environment, and on the other hand, it can strengthen the fixing effect of electronic components on the circuit board.

[0004] The existing silicone potting glue may occasionally have the following problems during use: the solidified colloid is separated from the shell of the packaging component, resulting in the barrier effect against water vapor, dust, etc. being difficult to achieve the expected effect. Summary of the invention

[0005] In order to improve the potting effect of organic silicone potting adhesive, the present application provides a flame retardant and thermally conductive organic silicone potting adhesive and a preparation method thereof.

[0006] In a first aspect, the present application provides a flame retardant thermally conductive silicone potting adhesive, which adopts the following technical solution: A flame retardant and heat conductive silicone potting adhesive comprises a resin body and a hardening composition which cooperate with each other, wherein the resin body comprises at least a base glue, a flame retardant and a heat conductive filler, and the hardening composition comprises a marginal hardener and an internal solidifying agent, wherein the acid ester content of the marginal hardener is greater than that of the internal solidifying agent, and a mixture formed by the marginal hardener and the resin body is used as a contact potting side boundary and surrounds a mixture formed by the internal solidifying agent and the resin body.

[0007] Optionally, the marginal hardener also includes glass fiber.

[0008] In a second aspect, the present application provides a method for preparing a flame retardant and thermally conductive silicone potting adhesive, using the following technical solution: A method for preparing a flame retardant and thermally conductive silicone potting adhesive, comprising: Step 1, preparing a resin body, which includes: weighing a base glue, a flame retardant, a thermal conductive filler and an auxiliary glue molding component, heating and stirring to obtain a resin body; wherein the base glue includes dimethylsiloxane; Step 2, preparing a hardening composition, which includes: weighing acid ester, silane and silicone oil, and differentially mixing the components in two cavities of a preset integrated dual-chamber stirring system to obtain a marginal hardener and an internal curing agent as the hardening composition; wherein the acid ester content in the two cavities of the integrated dual-chamber stirring system is different; Step 3: Preparation of potting glue, which includes: Calculate the length and height of the potting side boundary, obtain the preset margin thickness, and calculate the margin volume; Weighing the resin main body and the marginal hardener respectively according to the marginal volume in a preset mixing ratio of 1:1 to 1:1.2, and stirring to obtain a mixture 1; Weigh the resin body and the internal solidifying agent in a preset mixing ratio of 1.2:1 to 1:1, respectively, and stir to obtain a mixture 2; The mixture one and the mixture two form the potting compound.

[0009] Optionally, glass fibers are added during the process of preparing the hardened composition and processing the mixture.

[0010] Optionally, the integrated dual-chamber stirring system comprises: The material box is hollow inside and has a feeding port at the top and two discharging ports at the bottom; A movable partition, which is arranged in the material box and is used to separate the inner cavity of the material box into two cavities; A stirring mechanism, which is used to stir the materials in the two cavities in the material box respectively; a vibrating mechanism connected to the movable diaphragm; A negative pressure extraction mechanism connected to the inner cavity of the material box; and A valve group, which is installed at least at a feeding port and a discharging port of the material box; Among them, the movable partition includes a fixed plate, a movable plate and a cylinder. The fixed plate is fixed to the inner wall of the material box and has a connecting port along the thickness direction. The connecting ports are multiple and distributed along the length direction of the fixed plate. The upper part of the connecting port is open. The movable plate is located above the fixed plate and a baffle adapted to the connecting port is arranged at the lower part. A through groove is opened on the top of the material box. The movable plate passes through the through groove upward. The cylinder is installed on the top of the material box and is telescopically connected to the upper end of the movable plate.

[0011] Optionally, the stirring mechanism includes a stirring rod and a motor for driving the stirring rod to rotate, the stirring rod is arranged horizontally and the stirring section is located in the material box, and the rod end passes through; the two cavities of the material box each have at least one stirring rod, and the motor is installed on the outer wall of the material box.

[0012] Optionally, the vibration mechanism includes a contact rod and a vibration unit, wherein the contact rod passes through a setting plate and is plural in number, the contact rod is hollow and elastic, the vibration unit is built into the contact rod and is close to the setting plate, and conduction rods are respectively provided at both ends of the contact rod, and the conduction rods contact the vibration unit.

[0013] Optionally, it also includes a controller and a weighing sensor electrically connected to the controller, the material box falls on the weighing end of the weighing sensor, the controller is electrically connected to the stirring mechanism, the vibration mechanism, the negative pressure pumping mechanism and the valve group, and the controller is configured to control the vibration mechanism and the negative pressure pumping mechanism according to the weighing detection value of the weighing sensor.

[0014] In summary, the present application includes the following beneficial technical effects: the potting glue of the present application is different from the existing colloids, which are only single glue or divided into A and B glues, but are further differentiated into hardened components. During use, the staff can obtain colloids with different viscosities by respectively matching the resin main body with hardened components of different ingredients. Selectively using a colloid with better bonding effect on the periphery of the potting main body can retain the performance of the original potting glue while improving the potting effect of the silicone potting glue. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure after the potting glue of the present application is applied; Figure 2 It is a structural schematic diagram of the integrated dual-chamber stirring system of the present application; Figure 3 It is a schematic diagram of the longitudinal section structure of the fixed plate of the present application; Figure 4 It is a structural schematic diagram of the stirring mechanism of the present application; Figure 5 It is a schematic diagram of the control structure of the integrated dual-chamber stirring system of the present application.

[0016] Explanation of the reference numerals: 1. Material box; 2. Movable partition; 21. Fixed plate; 22. Moving plate; 221. Baffle; 23. Cylinder; 3. Stirring mechanism; 31. Stirring rod; 32. Motor; 4. Vibrating mechanism; 41. Contact rod; 42. Vibrating unit; 5. Negative pressure extraction mechanism; 6. Controller; 7. Weighing sensor. DETAILED DESCRIPTION

[0017] The following is combined with Figure 1-5 This application is described in further detail.

[0018] The embodiment of the present application discloses a flame retardant and thermally conductive silicone potting adhesive.

[0019] Reference Figure 1The flame retardant and thermally conductive silicone potting compound includes a resin main body and a hardening component. When used, the two are mixed in a certain proportion to obtain the silicone potting compound, which is then used for potting. The following is a specific explanation: In this embodiment, the resin body includes a base glue, a flame retardant, a thermal conductive filler, and an auxiliary glue molding component. Among them, the base glue includes dimethyl siloxane, the flame retardant includes aluminum hydroxide, the thermal conductive filler includes aluminum oxide, and the auxiliary agent can be a defoamer, which is used to eliminate bubbles in accordance with the design in the following method embodiment of this application. The specific role is described below; the auxiliary glue molding component includes a defoamer and an alcohol solution. The hardening composition includes acid esters, silanes and silicone oils. Acid esters include: fatty dibasic acid esters, phosphate esters; silanes include: propyl trioxysilane; silicone oils can be methyl or ethyl silicone oils. In this embodiment, silicone oil is added mainly to increase the moisture-proof properties of the colloid to meet the packaging requirements of electronic components.

[0020] It is understandable that the above components are all known chemical components and will not be described in detail. The focus of this application is on: 1) the hardening composition includes a marginal hardener and an internal curing agent, and the acid ester content of the marginal hardener is greater than that of the internal curing agent; 2) the hardening composition also includes glass fiber.

[0021] Regarding marginal hardeners and internal hardeners, specifically: In the present application, acid ester is mainly used to mix and react with base glue to solidify the liquid mixture, so it has some influence on the bonding of the potting glue after injection; the present application actively divides the hardening component into two parts, taking a boxed structure to be packaged as an example, wherein a mixture 1 formed by the marginal hardener and the resin body is used as the contact potting side boundary, and a mixture 2 formed by the internal curing agent and the resin body is used as the internal potting body, and the mixture 1 surrounds the mixture 2.

[0022] According to the above settings, the potting glue of the present application is different from the existing colloids, which are only single glue or divided into A and B glues, but are further differentiated into hardened components. During use, the staff can obtain colloids with different viscosities by respectively matching the resin main body with hardened components of different ingredients. Selectively using a colloid with better bonding effect on the periphery of the potting main body can retain the performance of the original potting glue while improving the potting effect of the silicone potting glue.

[0023] The hardening composition also includes glass fibers, specifically: It is known that glass fiber has good insulation and thermal conductivity. Therefore, adding it to the colloid will not cause the electronic components to be accidentally broken down and turned on, and on the other hand, it will ensure the heat dissipation of the original structure. It should be noted that in this embodiment, the glass fiber should be crushed, preferably within 2 mm in length, and the recommended amount is less than 3 parts in 100 parts of potting glue, so as to avoid excessive viscosity affecting the full mixing with the resin body. After the glass fiber is added, the mixture formed by mixing with the resin body is in contact with the outer structure of the package, and the glass fiber is mixed into the colloid, so the bonding effect is stronger after curing.

[0024] At the same time, because glass fiber is used and the hardening composition contains silane, the combination of glass fiber and resin is better to enhance the bonding effect on the peripheral structure of the package.

[0025] The embodiment of the present application also discloses a method for preparing a flame retardant and thermally conductive silicone potting adhesive.

[0026] The preparation method of the flame retardant thermal conductive silicone potting adhesive comprises: Step 1: preparing a resin body, which includes: weighing a base glue, a flame retardant, a thermal conductive filler and an auxiliary glue molding component, heating and stirring to obtain a resin body; wherein the base glue includes dimethylsiloxane.

[0027] The content of each component mentioned above can be preset by the staff, for example: 8:1:16:1; heating is required during the stirring and mixing process, and the heating temperature can be 130-180°C; the stirring in this link can be carried out using an existing stirring kettle.

[0028] Step 2: preparing a hardening composition, which includes: weighing acid esters, silanes and silicone oils, and differentially mixing the components in two cavities of a preset integrated dual-cavity stirring system to obtain a marginal hardener and an internal curing agent as the hardening composition.

[0029] Among them, the content of each component such as acid ester is also preset by the staff, for example: 4:1:9. It should be noted that in this method, in order to efficiently prepare the marginal hardener and internal curing agent of the hardening composition, the existing stirring kettle is no longer used as described above, but an integrated double-chamber stirring system is used for operation, which will be explained later.

[0030] Step 3: Preparation of potting glue, which includes: Calculate the length and height of the potting side boundary, obtain the preset margin thickness, and calculate the margin volume; Weighing the resin main body and the marginal hardener respectively according to the marginal volume in a preset mixing ratio of 1:1 to 1:1.2, and stirring to obtain a mixture 1; Weigh the resin body and the internal solidifying agent in a preset mixing ratio of 1.2:1 to 1:1, respectively, and stir to obtain a mixture 2; The mixture one and the mixture two form the potting compound.

[0031] The potting glue prepared as described above has a viscosity of about 20,000 cP. After pouring, it takes about 24 hours to solidify at room temperature. The higher the ambient temperature, the faster the solidification.

[0032] In another embodiment of the present application, glass fiber is added during the process of preparing the hardening composition and processing the mixture, that is, the glass fiber is not limited to being directly added to the marginal hardener, but can also be added during the process of mixing the marginal hardener and the resin body. The significance of adding glass fiber has been explained in the aforementioned other embodiments and will not be repeated here.

[0033] Reference Figure 2-4 In another embodiment of the present application, an integrated dual-chamber stirring system includes a material box 1, a movable partition 2, a stirring mechanism 3, a vibration mechanism 4, a negative pressure extraction mechanism 5 and a valve group.

[0034] The material box 1 is hollow inside and has a feeding port at the top and two discharging ports at the bottom. The material ports are formed into external tube structures so as to be connected with the feeding and receiving mechanisms.

[0035] The movable partition 2 is vertically set up in the inner cavity of the material box 1, dividing the inner cavity of the material box 1 into two left and right cavities, so as to be used for the production and processing of two mixtures at the same time. The movable partition 2 includes a fixed plate 21 and a movable plate 22. The bottom and both ends of the fixed plate 21 are fixed to the inner wall of the material box 1. The fixed plate 21 is provided with a connecting opening along the thickness direction. There are multiple connecting openings, which are arranged along the length direction of the fixed plate 21 and connected to the opening at the top. The movable plate 22 is located above the fixed plate 21, and a baffle 221 adapted to the connecting opening is formed on the movable plate 22; a through groove for the movable plate 22 to pass through is provided at the top of the material box 1, and a connecting plate is welded on the upper part of the movable plate 22; a cylinder 23 is fixed at the top of the material box 1 through a bracket, and the telescopic end of the cylinder 23 faces downward and is fixed to the connecting plate to connect the movable plate 22.

[0036] In the first half of the stirring, the cylinder 23 contracts and pulls the movable plate 22 upward, and the baffle 221 retreats to open the connecting port to allow the two cavities in the material box 1 to communicate with each other. At this stage, the added components in the two cavities are the same, which accelerates the mixing and ensures the consistency of the composition as much as possible; in the second half of the stirring, the cylinder 23 extends and pushes the movable plate 22 downward, and the baffle 221 closes the connecting port to separate the two cavities in the material box 1. At this stage, the staff continues to feed the acid ester component to the feeding port of the corresponding cavity through the feeding port. After the feeding is completed, the feeding port is closed, and the vibration mechanism 4 and the negative pressure extraction mechanism 5 are started to complete the mixing work synchronously and differentially to produce two different hardened compositions.

[0037] It is understandable that, in order to ensure air tightness, a sealing sheet may be fixed at the bottom of the connecting plate at the top of the moving plate 22 .

[0038] Because the bonding effect of the sealant needs to be improved in this application, and more bubbles in the sealant will have an adverse effect, so the present application sets a vibration mechanism 4 and a negative pressure extraction mechanism 5, and also improves the stirring mechanism 3 to cooperate, specifically: The stirring mechanism 3 includes a stirring rod 31 and a motor 32. The stirring rod 31 is arranged horizontally, and the stirring section is located in the material box 1, and the rod end passes through the material box 1; the motor 32 is fixed to the outer wall of the material box 1, and the output shaft fixes the stirring rod 31. In this embodiment, one cavity of the material box 1 corresponds to one stirring rod 31, and the motor 32 can be one stirring rod 31 corresponding to one motor 32, or one motor can drive two stirring rods 31 through a belt transmission mechanism.

[0039] According to the above configuration, the stirring rod 31 can be used to stir the material in the material box 1, and the stirred material can be more easily turned over to a position close to the liquid surface, especially when the stirring section of the stirring rod 31 is not completely submerged, so that the bubbles in the material can be better discharged in cooperation with the negative pressure extraction mechanism 5.

[0040] Reference Figure 3 The vibration mechanism 4 includes a contact rod 41 and a vibration unit 42. The contact rod 41 passes through the setting plate 21 horizontally. The contact rod 41 is a hollow structure and has elasticity, such as a rubber rod with a protective coating. The vibration unit 42 is built into the contact rod 41 and is located at the position of the setting plate 21. Conduction rods are respectively arranged at both ends of the interior of the contact rod 41, and the conduction rods contact the vibration unit 42. There are multiple contact rods 41, and at least one vibration unit 42 is installed in each contact rod 41. The vibration unit 42 can be a vibration motor.

[0041] When the moving plate 22 moves downward or completes the downward movement, the vibration unit 42 is turned on to drive the contact rod 41 to vibrate, thereby accelerating the discharge of bubbles in the material through high-speed vibration; and it can also be turned on after the stirring is completed; and because of the structural setting of the vibration mechanism 4, the utilization rate of the vibration unit 42 can be higher, and the production is more energy-saving.

[0042] Reference Figure 5 The negative pressure extraction mechanism 5 includes a vacuum pump or a fan, whose air inlet is connected to the material box 1 through a pipeline and the connection point is located at the top. The valve group includes a plurality of electric valves, which are respectively installed on the feeding port, the discharging port and each pipeline. When the moving plate 22 moves downward or completes the downward movement, the negative pressure extraction mechanism 5 is turned on to accelerate the discharge of bubbles in the material.

[0043] Reference Figure 5In another embodiment of the present application, it also includes a controller 6, which is electrically connected to a weighing sensor 7, and is electrically connected to the above-mentioned stirring mechanism 3, vibration mechanism 4, negative pressure pumping mechanism 5 and valve group, and the controller is configured to control the vibration mechanism 4 and the negative pressure pumping mechanism 5 according to the weighing detection value of the weighing sensor 7.

[0044] Example: According to the aforementioned embodiments, the hardening composition has a formula, and each component has a corresponding proportion. Therefore, the controller can calculate the amount of each component according to the proportion and the weighing detection value. It is known that the amount of bubbles generated when the amount of the component is different is different. The more bubbles there are, the faster the vibration mechanism 4 needs to vibrate and the greater the suction power / longer the suction time of the negative pressure mechanism 5. Therefore, an empirical database can be established, and after the amount of each component is known, the vibration mechanism 4 and the negative pressure mechanism 5 can be adjusted accordingly to achieve a better defoaming effect.

[0045] It is understandable that when mixing the resin body and the hardening component, the above-mentioned integrated dual-chamber stirring system can also be used to ensure the quality of the obtained potting compound.

[0046] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A flame retardant and heat conductive silicone potting adhesive, comprising a resin body and a hardening component that cooperate with each other, characterized in that: The resin body includes at least a base glue, a flame retardant and a thermally conductive filler, the hardening composition includes a marginal hardener and an internal solidifier, the acid ester content of the marginal hardener is greater than that of the internal solidifier, and a mixture formed by the marginal hardener and the resin body is used as a contact encapsulation side boundary and surrounds a mixture formed by the internal solidifier and the resin body.

2. The flame retardant and thermally conductive silicone potting adhesive according to claim 1, characterized in that: The marginal hardener also includes glass fibers.

3. A method for preparing a flame retardant and thermally conductive silicone potting adhesive, characterized in that: include: Step 1, preparing a resin body, which includes: weighing a base glue, a flame retardant, a thermal conductive filler and an auxiliary glue molding component, heating and stirring to obtain a resin body; wherein the base glue includes dimethylsiloxane; Step 2, preparing a hardening composition, which includes: weighing acid ester, silane and silicone oil, and differentially mixing the components in two cavities of a preset integrated dual-chamber stirring system to obtain a marginal hardener and an internal curing agent as the hardening composition; wherein the acid ester content in the two cavities of the integrated dual-chamber stirring system is different; Step 3: Preparation of potting glue, which includes: Calculate the length and height of the potting side boundary, obtain the preset margin thickness, and calculate the margin volume; Weighing the resin main body and the marginal hardener respectively according to the marginal volume in a preset mixing ratio of 1:1 to 1:1.2, and stirring to obtain a mixture 1; Weigh the resin body and the internal solidifying agent in a preset mixing ratio of 1.2:1 to 1:1, respectively, and stir to obtain a mixture 2; The mixture one and the mixture two form the potting compound.

4. The method for preparing the flame retardant and thermally conductive silicone potting adhesive according to claim 3, characterized in that: Glass fibers are added during the process of preparing the hardened composition and processing the mixture.

5. The method for preparing the flame retardant and thermally conductive silicone potting adhesive according to claim 3, characterized in that: The integrated dual-chamber stirring system comprises: A material box (1) is hollow inside and has a feeding port at the top and two discharging ports at the bottom; A movable partition (2) is arranged in the material box (1) and is used to separate the inner cavity of the material box (1) to form two cavities; A stirring mechanism (3) for stirring the materials in the two cavities in the material box (1) respectively; A vibration mechanism (4) connected to the movable partition (2); a negative pressure extraction mechanism (5), which is connected to the inner cavity of the material box (1); and A valve group, which is installed at least at a feeding port and a discharging port of the material box (1); The movable partition (2) comprises a fixed plate (21), a movable plate (22) and a cylinder (23); the fixed plate (21) is fixed to the inner wall of the material box (1) and has a communication opening along the thickness direction; the communication opening is multiple and distributed along the length direction of the fixed plate (21); the upper part of the communication opening is open; the movable plate (22) is located above the fixed plate (21) and has a baffle (221) adapted to the communication opening at the lower part; a through groove is formed at the top of the material box (1); the movable plate (22) passes through the through groove upward; and the cylinder (23) is installed at the top of the material box (1) and is telescopically connected to the upper end of the movable plate (22).

6. The method for preparing the flame retardant and thermally conductive silicone potting adhesive according to claim 5, characterized in that: The stirring mechanism (3) comprises a stirring rod (31) and a motor (32) for driving the stirring rod (31) to rotate; the stirring rod (31) is arranged horizontally and the stirring section is located in the material box (1), with the rod end protruding; the two cavities of the material box (1) each have at least one stirring rod (31), and the motor (32) is mounted on the outer wall of the material box (1).

7. The method for preparing the flame retardant and thermally conductive silicone potting adhesive according to claim 5, characterized in that: The vibration mechanism (4) comprises a contact rod (41) and a vibration unit (42); the contact rod (41) passes through a setting plate (21) and is in plurality; the contact rod (41) is hollow and elastic; the vibration unit (42) is built into the contact rod (41) and is close to the setting plate (21); conductive rods are respectively provided at both ends of the contact rod (41); the conductive rods contact the vibration unit (42).

8. The method for preparing the flame retardant and thermally conductive silicone potting adhesive according to claim 5, characterized in that: It also includes a controller (6) and a weighing sensor (7) electrically connected to the controller (6), the material box (1) falls on the weighing end of the weighing sensor (7), the controller (6) is electrically connected to the stirring mechanism (3), the vibration mechanism (4), the negative pressure extraction mechanism (5) and the valve group, and the controller (6) is configured to control the vibration mechanism (4) and the negative pressure extraction mechanism (5) according to the weighing detection value of the weighing sensor (7).

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