Thermally conductive epoxy resin composition, preparation method thereof and circuit board

Abstract

The present application discloses a thermally conductive epoxy resin composition, a preparation method thereof, and a circuit board, including: obtaining a thermally conductive filler; wherein the thermally conductive filler is a magnesium borate composite whisker having boron nitride nanosheets grown on the surface; obtaining an epoxy resin, adding a thermally conductive filler to the epoxy resin, and stirring evenly to obtain a first mixed solution; heating and curing the first mixed solution to obtain a thermally conductive epoxy resin composition; wherein the thermally conductive filler is distributed in any direction in the epoxy resin. The present application can effectively improve the thermal conductivity of the resin by obtaining a magnesium borate composite whisker having boron nitride nanosheets grown on the surface and adding it to the epoxy resin as a thermally conductive filler. And because the thermally conductive filler can be filled in the epoxy resin in any direction, the boron nitride nanosheets can be filled in the epoxy resin in any direction, and a thermal conductive path can be formed in all directions, thereby greatly improving the thermal conductivity of the thermally conductive epoxy resin composition.

Description

Technical Field

[0001] The present application relates to the technical field of circuit boards, and in particular to a thermally conductive epoxy resin composition and a preparation method thereof, as well as a circuit board. Background Art

[0002] With the rapid development of high-density printed circuit boards (PCBs), the requirements for heat dissipation in printed circuit boards are getting higher and higher. Currently, epoxy resin (EP) is mostly used as a prepreg or solder mask ink in PCB boards. Due to the existence of gaps, interface defects, chain entanglement and random orientation in epoxy resin, the thermal conductivity of epoxy resin is often low and cannot meet the heat dissipation needs of the electronics industry.

[0003] In the prior art, in order to improve the thermal conductivity of epoxy resin and ensure the insulation performance of high molecular polymer, high thermal conductivity fillers are generally added to epoxy resin to achieve its insulation and thermal conductivity, for example, traditional thermal conductive fillers such as aluminum oxide and aluminum nitride or new materials such as boron nitride are added.

[0004] However, adding aluminum oxide or aluminum nitride will lead to a significant increase in the dielectric constant and hardness of the PCB; boron nitride has good thermal conductivity and excellent node performance, but boron nitride generally has a flaky structure and is directional and horizontally distributed in the plate, and cannot form a thermal conduction path in the vertical direction of the plate, making it difficult to effectively exert its high thermal conductivity characteristics. Summary of the invention

[0005] The main technical problem solved by the present application is to provide a thermally conductive epoxy resin composition and a preparation method thereof and a circuit board, which can solve the problem that the insulation performance of the epoxy resin decreases due to the existing thermally conductive fillers and the thermal conductivity cannot be significantly improved.

[0006] In order to solve the above technical problems, the first technical solution adopted in the present application is to provide a method for preparing a thermally conductive epoxy resin composition, comprising: obtaining a thermally conductive filler; wherein the thermally conductive filler is a magnesium borate composite whisker with boron nitride nanosheets grown on the surface; obtaining an epoxy resin, adding the thermally conductive filler to the epoxy resin, and stirring evenly to obtain a first mixed solution; heating and curing the first mixed solution to obtain a thermally conductive epoxy resin composition; wherein the thermally conductive filler is distributed in the epoxy resin in any direction.

[0007] Among them, the step of obtaining the thermally conductive filler includes: obtaining magnesium borate whiskers and placing the magnesium borate whiskers in a tubular furnace; evacuating the tubular furnace and pre-passing ammonia; heating to a first set temperature and keeping it warm for a first set time in an ammonia atmosphere; and obtaining the thermally conductive filler after natural cooling.

[0008] Among them, after the tubular furnace is vacuumed, the step of pre-passing ammonia includes: controlling the flow rate of ammonia to 150-200 ml / min; the step of heating to a first set temperature and keeping it warm for a first set time under an ammonia atmosphere includes: heating to 980-1020°C under an ammonia atmosphere and keeping it warm for 3-4 hours.

[0009] Among them, the step of obtaining epoxy resin, adding thermally conductive filler to the epoxy resin, and stirring evenly to obtain a first mixed solution includes: obtaining epoxy resin and a curing agent, adding thermally conductive filler and curing agent to the epoxy resin, stirring evenly, and obtaining a first mixed solution.

[0010] Among them, the steps of obtaining epoxy resin and curing agent, adding thermal conductive filler and curing agent to the epoxy resin, stirring evenly, and obtaining a first mixed solution include: preparing the following raw materials according to preset weight portions: epoxy resin, 100 parts; thermal conductive filler, 6 to 10 parts; curing agent, 25 parts; adding the thermal conductive filler and curing agent into the epoxy resin according to the raw material ratio, stirring evenly to obtain the first mixed solution.

[0011] The epoxy resin includes bisphenol A epoxy resin, and the curing agent includes polyetheramine D230.

[0012] The stirring time is controlled to be 1 to 1.5 hours.

[0013] In order to solve the above technical problems, the second technical solution adopted in the present application is to provide a thermally conductive epoxy resin composition, which includes an epoxy resin and a thermally conductive filler filled in the epoxy resin; wherein the thermally conductive filler is a magnesium borate composite whisker with boron nitride nanosheets grown on the surface; wherein the thermally conductive filler is distributed in the epoxy resin in any direction.

[0014] The mass ratio of the thermal conductive filler to the epoxy resin is in the range of 6 to 10:100.

[0015] In order to solve the above technical problems, the third technical solution adopted in the present application is to provide a circuit board, which includes at least one sheet of the thermally conductive epoxy resin composition as described above.

[0016] The beneficial effects of the present application are as follows: Different from the prior art, the present application provides a thermally conductive epoxy resin composition, a preparation method thereof, and a circuit board. By obtaining a magnesium borate composite whisker having boron nitride nanosheets grown on the surface, and adding it to the epoxy resin as a thermally conductive filler, so that the epoxy resin is filled with boron nitride nanosheets, the high thermal conductivity and insulation properties of boron nitride can be utilized to effectively improve the thermal conductivity of the resin. Furthermore, since the structure of the magnesium borate composite whisker is rod-shaped and has a certain aspect ratio, and it can be filled in the epoxy resin in any direction, the boron nitride nanosheets attached thereto can be filled in the epoxy resin in any direction, and a thermal conductive path can be formed in all directions, thereby greatly improving the thermal conductivity of the thermally conductive epoxy resin composition. The present application can meet the heat dissipation requirements of the circuit board by preparing the above-mentioned thermally conductive epoxy resin composition and applying it in the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a schematic flow chart of a first embodiment of a method for preparing a thermally conductive epoxy resin composition of the present application;

[0019] Figure 2 It is a schematic flow chart of a second embodiment of the method for preparing a thermally conductive epoxy resin composition of the present application;

[0020] Figure 3 is a process flow chart of the present application for preparing a thermally conductive epoxy resin composition;

[0021] Figure 4 yes Figure 3 Scanning electron microscope image of the thermally conductive epoxy resin composition prepared in . DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "said", and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless otherwise clearly indicated above, and "multiple" generally includes at least two, but does not exclude the inclusion of at least one.

[0024] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0025] It should be understood that the terms "include", "comprises" or any other variations used herein are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "includes..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0026] Currently, epoxy resin (EP) is mostly used as prepreg or solder mask in PCB boards. Due to the existence of gaps, interface defects, chain entanglement and random orientation in epoxy resin, the thermal conductivity of epoxy resin is often low (between 0.1 and 0.35 W·m -1 ·K -1 It is within the range of , and cannot meet the heat dissipation needs of the electronics industry.

[0027] In the prior art, in order to improve the thermal conductivity of epoxy resin and ensure the insulation performance of high molecular polymer, high thermal conductivity fillers are generally added to epoxy resin to achieve its insulation and thermal conductivity. For example, traditional thermal conductive fillers such as aluminum oxide and aluminum nitride or new materials such as boron nitride are added. However, the addition of aluminum oxide or aluminum nitride will greatly increase the dielectric constant and hardness of the PCB; boron nitride has good thermal conductivity and excellent node performance, but boron nitride is a flaky structure and will be oriented and horizontally distributed in the plate, and it is impossible to form a thermal conductive path in the vertical direction of the plate, and it is difficult to effectively exert its high thermal conductivity.

[0028] Based on the above situation, the present application provides a thermally conductive epoxy resin composition and a preparation method thereof, as well as a circuit board, which can solve the problem that the insulation performance of the epoxy resin decreases due to the existing thermally conductive fillers and the thermal conductivity cannot be significantly improved.

[0029] The present application is described in detail below with reference to the accompanying drawings and implementation methods.

[0030] See also Figure 1 , Figure 1 1 is a schematic flow chart of a first embodiment of a method for preparing a thermally conductive epoxy resin composition of the present invention. In this embodiment, the preparation method comprises:

[0031] S11: Obtain a thermally conductive filler; wherein the thermally conductive filler is a magnesium borate composite whisker with boron nitride nanosheets grown on the surface.

[0032] In this embodiment, the thermal conductive filler is magnesium borate whisker (Mg 2 B 2 O 5 ) as raw material, in ammonia (NH 3 Specifically, after the magnesium borate whisker reacts with ammonia, boron nitride (BN) nanosheets are in-situ generated on the surface of the magnesium borate whisker, and a magnesium borate mixture is formed inside the magnesium borate whisker.

[0033] Among them, magnesium borate whiskers are a type of rod-shaped crystal fiber material with a certain aspect ratio that grows in the form of single crystals. Its diameter is very small, about 0.5 to 2.0 μm. The atomic arrangement in the whiskers is highly ordered, and the strength is close to the theoretical strength of the atomic valence bond of the complete crystal. Therefore, magnesium borate whiskers have good mechanical strength, high strength modulus and high Young's modulus. When used for the reinforcement and modification of polymers, it shows excellent physical, chemical properties and excellent mechanical properties. It is an ideal modified filler for composite materials and functional materials.

[0034] Furthermore, since magnesium borate whiskers are inexpensive, using them as raw materials to prepare thermally conductive fillers can effectively reduce the preparation cost of thermally conductive fillers.

[0035] Among them, boron nitride (BN) nanosheets have good thermal conductivity and excellent dielectric properties.

[0036] S12: Obtain epoxy resin, add thermal conductive filler into the epoxy resin, and stir evenly to obtain a first mixed solution.

[0037] In this embodiment, a thermally conductive filler is added to the epoxy resin and stirred for a set time in a high-speed stirring mode, so that the thermally conductive filler can be evenly distributed in the epoxy resin.

[0038] S13: Curing the first mixed solution by increasing the temperature to obtain a thermally conductive epoxy resin composition; wherein the thermally conductive filler is distributed in the epoxy resin in any direction.

[0039] Understandably, the thermally conductive filler is distributed in the epoxy resin in any direction, indicating that the magnesium borate composite whiskers can be uniformly filled in the three-dimensional space of the epoxy resin in any direction, so that the boron nitride nanosheets can form thermal conductive pathways in multiple directions to give full play to their high thermal conductivity properties, thereby effectively improving the thermal conductivity of the epoxy resin.

[0040] Furthermore, since pure boron nitride is not directly added to the epoxy resin, the amount of boron nitride used can be reduced, thereby reducing the preparation cost of the thermally conductive epoxy resin composition.

[0041] Different from the prior art, this embodiment obtains magnesium borate composite whiskers with boron nitride nanosheets grown on the surface, and adds them to epoxy resin as thermal conductive fillers, so that the epoxy resin is filled with boron nitride nanosheets, and can effectively improve the thermal conductivity of the resin by utilizing the high thermal conductivity and insulation properties of boron nitride. Furthermore, since the structure of the magnesium borate composite whiskers is rod-shaped and has a certain aspect ratio, and it can be filled in the epoxy resin in any direction, the boron nitride nanosheets attached thereto can be filled in the epoxy resin in any direction, and form a thermal conductive path in all directions, thereby greatly improving the thermal conductivity of the thermally conductive epoxy resin composition.

[0042] See also Figure 2 , Figure 2 1 is a schematic flow chart of a second embodiment of the method for preparing a thermally conductive epoxy resin composition of the present application. In this embodiment, the preparation method comprises:

[0043] S21: Obtain magnesium borate whiskers, and place the magnesium borate whiskers in a tubular furnace.

[0044] S22: After the tubular furnace is evacuated, ammonia gas is pre-flowed.

[0045] In this embodiment, the flow rate of ammonia gas is controlled to be 150-200 ml / min.

[0046] Among them, the preferred flow rate is 200 ml / min.

[0047] In other implementation scenarios, nitrogen (N 2 ), nitrogen and hydrogen (H 2 ) mixed gas, etc., only needs to ensure that it is a nitrogen-containing atmosphere, and this application does not impose any limitation on this.

[0048] S23: Raising the temperature to a first set temperature and keeping the temperature for a first set time in an ammonia atmosphere.

[0049] In this embodiment, the temperature is raised to 980 to 1020° C. in an ammonia atmosphere and maintained for 3 to 4 hours.

[0050] Among them, the preferred first set temperature is 1000° C., and the preferred insulation time is 4 hours.

[0051] S24: After natural cooling, a thermally conductive filler is obtained; wherein the thermally conductive filler is a magnesium borate composite whisker with boron nitride nanosheets grown on the surface.

[0052] In this embodiment, the following chemical reactions may occur during the preparation of the thermally conductive filler:

[0053] 3Mg 2 B 2 O 5 (s)+2NH 3 (g)→2BN(s)+3H 2 O(g)+2Mg 3 B 2 O 6 (s) (1)

[0054] Specifically, NH 3 Decomposes into N at high temperature 2 (nitrogen) and H 2 (Hydrogen), in this reducing atmosphere, as the temperature gradually rises, Mg 2 B 2 O 5 The surface layer is etched and decomposed into a local molten state, adsorbed on Mg 2 B 2 O 5 NH 3 The active N (nitrogen) atoms formed by decomposition diffuse into the Mg 2 B 2 O 5 The active B (boron) atoms on the surface form BN (boron nitride), and the inside of the whiskers forms Mg 3 B 2 O 6 (Magnesium Borate Mixture).

[0055] S25: Obtain epoxy resin and curing agent, add thermal conductive filler and curing agent to the epoxy resin, stir evenly, and obtain a first mixed solution.

[0056] In this embodiment, the following raw materials are prepared according to preset weight portions: epoxy resin, 100 parts; thermal conductive filler, 6-10 parts; curing agent, 25 parts. The thermal conductive filler and curing agent are added to the epoxy resin according to the raw material ratio, and stirred evenly to obtain a first mixed solution.

[0057] The epoxy resin includes bisphenol A epoxy resin, and the curing agent includes polyetheramine D230.

[0058] Specifically, polyetheramine D230, as a high-performance curing agent for epoxy resin, can produce high-strength and high-toughness composite materials.

[0059] In other embodiments, the epoxy resin may also be a bisphenol F epoxy resin, which is not limited in the present application.

[0060] In this embodiment, the stirring time is controlled to be 1 to 1.5 hours.

[0061] The stirring method is high-speed stirring.

[0062] The first mixed solution may be stirred by using processes such as ultrasonic dispersion or blending.

[0063] Specifically, the dispersing effect of ultrasound in liquid mainly depends on the ultrasonic cavitation of the liquid. When ultrasonic dispersion is used, there is no need to use a dispersant. Ultrasonic dispersion can obtain micron or even nanoparticles. When ultrasonic vibration is transmitted to the liquid, due to the high sound intensity, a strong cavitation effect will be stimulated in the liquid, thereby generating a large number of cavitation bubbles in the liquid. As these cavitation bubbles are generated and exploded, microjets will be generated to crush the large solid particles in the liquid. At the same time, due to the vibration and dispersing effect of ultrasound, the solid and liquid can be mixed more fully.

[0064] S26: Curing the first mixed solution by increasing the temperature to obtain a thermally conductive epoxy resin composition; wherein the thermally conductive filler is distributed in the epoxy resin in any direction.

[0065] Specifically, see Figure 3 and Figure 4 , Figure 3 is a process flow chart of preparing a thermally conductive epoxy resin composition in the present application, Figure 4 yes Figure 3 Scanning electron microscope image of the thermally conductive epoxy resin composition prepared in .

[0066] In this embodiment, magnesium borate whiskers 10 are obtained and placed in a tubular furnace. After the tubular furnace is evacuated, ammonia is pre-passed and the flow rate of ammonia is controlled to be 200 ml / min. The temperature is raised to 1000°C in an ammonia atmosphere and kept warm for 4 hours. After natural cooling, a thermally conductive filler 20 is obtained, wherein the thermally conductive filler 20 is a magnesium borate composite whisker 21 with boron nitride nanosheets 22 grown on the surface. Epoxy resin 30 and curing agent (not shown) are obtained according to preset weight portions, and the thermally conductive filler 20 and the curing agent are added to the epoxy resin 30 according to the raw material ratio, and the first mixed solution is obtained after stirring evenly. The first mixed solution is heated and cured to obtain a thermally conductive epoxy resin composition 40. Among them, the thermally conductive filler 20 is distributed in any direction in the epoxy resin 30.

[0067] Different from the prior art, this embodiment obtains magnesium borate composite whiskers with boron nitride nanosheets grown on the surface, and adds them to epoxy resin as thermal conductive fillers, so that the epoxy resin is filled with boron nitride nanosheets, and can effectively improve the thermal conductivity of the resin by utilizing the high thermal conductivity and insulation properties of boron nitride. Furthermore, since the structure of the magnesium borate composite whiskers is rod-shaped and has a certain aspect ratio, and it can be filled in the epoxy resin in any direction, the boron nitride nanosheets attached thereto can be filled in the epoxy resin in any direction, and form a thermal conductive path in all directions, thereby greatly improving the thermal conductivity of the thermally conductive epoxy resin composition.

[0068] Correspondingly, the present application provides a thermally conductive epoxy resin composition.

[0069] In this embodiment, the thermally conductive epoxy resin composition is prepared by the above-mentioned method for preparing the thermally conductive epoxy resin composition.

[0070] Specifically, the thermally conductive epoxy resin composition includes an epoxy resin and a thermally conductive filler filled in the epoxy resin. The thermally conductive filler is a magnesium borate composite whisker with boron nitride nanosheets grown on the surface. The thermally conductive filler is distributed in any direction in the epoxy resin. The mass ratio of the thermally conductive filler to the epoxy resin is in the range of 6 to 10:100.

[0071] Different from the prior art, the thermally conductive epoxy resin composition provided in this embodiment can give full play to the high thermal conductivity of boron nitride nanosheets, thereby improving the thermal conductivity of epoxy resin, and then making the thermally conductive epoxy resin composition have better thermal conductivity and can be applied in the field of electronics industry.

[0072] Correspondingly, the present application provides a circuit board, the circuit board comprising at least one thermally conductive epoxy resin composition as described above. Specifically, the thermally conductive epoxy resin composition can be used as a prepreg or a plugging resin in a PCB.

[0073] It can be understood that since boron nitride material has high thermal conductivity and insulation properties, it can maintain the insulation performance of epoxy resin and effectively improve the thermal conductivity of insulating resin. Moreover, since the thermally conductive filler is distributed in any direction in the epoxy resin, it can also form thermal conductive channels in various directions in the thermally conductive epoxy resin composition, so it can effectively dissipate heat for PCB, thereby meeting the heat dissipation requirements of the circuit board, and then promoting the application of epoxy resin in PCB with high thermal conductivity requirements.

[0074] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for preparing a thermally conductive epoxy resin composition, characterized in that: include: A thermally conductive filler is obtained; wherein the thermally conductive filler is a magnesium borate composite whisker with boron nitride nanosheets grown on the surface; specifically comprising: obtaining a magnesium borate whisker, placing the magnesium borate whisker in a tubular furnace; evacuating the tubular furnace, and pre-passing ammonia; heating to a first set temperature in an ammonia atmosphere and keeping the temperature for a first set time; after natural cooling, obtaining the thermally conductive filler; Obtaining epoxy resin, adding the thermal conductive filler into the epoxy resin, and stirring evenly to obtain a first mixed solution; The first mixed solution is cured by heating to obtain the thermally conductive epoxy resin composition; wherein the thermally conductive filler is distributed in any direction in the epoxy resin.

2. The preparation method according to claim 1, characterized in that: The step of pre-passing ammonia gas after the tube furnace is vacuumed comprises: Control the flow rate of the ammonia gas to 150-200 ml / min; The step of heating the mixture to a first set temperature and keeping the temperature for a first set time under an ammonia atmosphere comprises: The temperature is raised to 980-1020° C. in the ammonia atmosphere and maintained at this temperature for 3-4 hours.

3. The preparation method according to claim 2, characterized in that: The step of obtaining the epoxy resin, adding the thermally conductive filler to the epoxy resin, and stirring the mixture to obtain a first mixed solution comprises: The epoxy resin and the curing agent are obtained, the thermal conductive filler and the curing agent are added to the epoxy resin, and the mixture is stirred evenly to obtain the first mixed solution.

4. The preparation method according to claim 3, characterized in that: The step of obtaining the epoxy resin and the curing agent, adding the thermal conductive filler and the curing agent to the epoxy resin, and stirring evenly to obtain the first mixed solution includes: Prepare the following raw materials according to preset weight portions: 100 parts of the epoxy resin; 6-10 parts of the thermal conductive filler; 25 parts of the curing agent; The thermal conductive filler and the curing agent are added into the epoxy resin according to the raw material ratio, and the first mixed solution is obtained after stirring evenly.

5. The preparation method according to claim 4, characterized in that: The epoxy resin includes bisphenol A epoxy resin, and the curing agent includes polyetheramine D230.

6. The preparation method according to claim 4, characterized in that: The stirring time is controlled to be 1 to 1.5 hours.

7. A thermally conductive epoxy resin composition, characterized in that: The thermally conductive epoxy resin composition is prepared by the preparation method of the thermally conductive epoxy resin composition according to any one of claims 1 to 6, and the thermally conductive epoxy resin composition comprises an epoxy resin and a thermally conductive filler filled in the epoxy resin; wherein the thermally conductive filler is a magnesium borate composite whisker having boron nitride nanosheets grown on the surface; the magnesium borate composite whisker is prepared using magnesium borate whiskers as raw materials in an ammonia atmosphere; wherein the thermally conductive filler is distributed in the epoxy resin in any direction.

8. The thermally conductive epoxy resin composition according to claim 7, characterized in that: The mass ratio of the thermally conductive filler to the epoxy resin is in the range of 6 to 10:

100.

9. A circuit board, characterized in that: The circuit board comprises at least one sheet of the thermally conductive epoxy resin composition according to claim 7.

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