Flake graphite dispersion and its preparation method and application

Abstract

The present application provides a flake graphite dispersion, its preparation method, and application. The above-mentioned flake graphite dispersion preparation method includes the following steps: obtaining the following components of the flake graphite dispersion: natural graphite, a surfactant, a dispersant, and a thickener; subjecting the natural graphite to acid treatment to obtain expandable graphite; adding the surfactant and dispersant to the expandable graphite and performing a cooling and grinding operation to obtain a grind, wherein the particle size D50 of the expandable graphite in the grind is 0.5μm to 0.8μm; adding the thickener to the grind to perform a mixing operation to obtain a flake graphite dispersion. The flake graphite dispersion prepared by the above-mentioned flake graphite dispersion preparation method can quickly form a conductive layer of a certain thickness and uniform connection on the hole wall of the PCB board, and has low pollution, high conductivity, and good dispersibility.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board processing, in particular to a flake graphite dispersion liquid and a preparation method and application thereof. Background Art

[0002] In the processing of multi-layer circuit boards, hole metallization technology is one of the key processes, and the hole metallization process is mostly completed by chemical copper deposition. Since the copper deposition solution used in chemical copper deposition contains more chemical substances that have a greater impact on the environment, it is now more advocated to use direct electroplating process to replace the chemical copper deposition process. The direct electroplating process is: after the epoxy group of the PCB board is destroyed by resin drilling, the surface charge property is negative. The hole wall is cleaned and the hole is filled. The solution used for filling the hole is acidic. Its main function is to adjust the charge on the resin surface so that the surface charge property inside the hole is positive, so as to complete electrostatic adsorption with the negatively charged particles in the hole metallization dispersion to form a dense and uniform conductive layer, followed by further copper plating.

[0003] Existing dispersions for hole metallization contain graphite, carbon black, carbon nanotubes, or mixtures thereof as the main components. For example, Chinese patent CN114845480A discloses using a graphene oxide aqueous solution to soak a copper-clad laminate before copper plating. While graphene oxide has good dispersibility and adheres well to the hole walls, its poor electrical conductivity necessitates repeated attachment to the PCB board. Furthermore, while graphene, carbon black, and carbon nanotubes have good electrical conductivity, they all have poor water dispersibility. Even when small dispersed particles are formed, they are susceptible to significant aggregation and growth in aqueous systems. This makes it difficult to ensure uniform treatment of the hole walls with the dispersion containing graphene, carbon black, and / or carbon nanotubes, and can even lead to hole clogging, which can further impact subsequent electroplating and easily result in a resistance of the entire PCB board exceeding 10 kΩ after hole metallization. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a flake graphite dispersion liquid that can quickly form a conductive layer of a certain thickness and uniform connection on the hole wall of a PCB board, and has low pollution, high conductivity and good dispersibility, as well as a preparation method and application thereof.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A method for preparing a flake graphite dispersion comprises the following steps:

[0007] Obtaining the following components of a flake graphite dispersion: natural graphite, a surfactant, a dispersant, and a thickener;

[0008] treating the natural graphite with acid to obtain expandable graphite;

[0009] Adding the surfactant and dispersant to the expandable graphite and performing a cooling and grinding operation to obtain a grind, wherein the particle size D50 of the expandable graphite in the grind is 0.5 μm to 0.8 μm;

[0010] The thickener is added to the ground material and mixed to obtain a flake graphite dispersion.

[0011] In one embodiment, the adding of the surfactant and dispersant into the expandable graphite for cooling and grinding specifically comprises the following steps:

[0012] adding the surfactant, dispersant and expandable graphite into a dispersion medium and performing a wetting and stirring operation to obtain a wet mixture;

[0013] The wet mixture is added to a crusher stripper for cryogenic grinding.

[0014] In one embodiment, the dispersion medium is deionized water.

[0015] In one embodiment, the dispersion medium includes deionized water and N-methylpyrrolidone.

[0016] In one embodiment, the temperature of adding the wet mixture to the crusher and stripping device for cryogenic grinding is 2°C to 8°C.

[0017] In one embodiment, the surfactant is sodium lauryl sulfate and / or alkylphenol polyoxyethylene ether.

[0018] In one embodiment, the dispersant is polyvinylpyrrolidone.

[0019] In one embodiment, the thickener is sodium carboxymethyl cellulose or ethylene-acrylic acid copolymer.

[0020] A flake graphite dispersion is prepared by the method for preparing a flake graphite dispersion according to any of the above embodiments, wherein the flake graphite dispersion further comprises a defoaming agent and a pH regulator.

[0021] In one embodiment, the defoaming agent is silicone oil cream.

[0022] In one embodiment, the pH adjuster is sodium carbonate.

[0023] An application of a flake graphite dispersion, wherein the flake graphite dispersion described in any of the above embodiments is used for hole metallization of a PCB board.

[0024] Compared with the prior art, the present invention has at least the following advantages:

[0025] The method for preparing a flake graphite dispersion of the present invention uses natural graphite, a surfactant, a dispersant, and a thickener to prepare the flake graphite dispersion, which has low pollution. The natural graphite is further acid-treated to insert sulfuric acid molecules or nitric acid molecules into the interlayers of the natural graphite to form a graphite intercalation compound, namely, expandable graphite. When the interlayers of the natural graphite are rapidly heated, the interlayers of the natural graphite expand to obtain graphite with a honeycomb structure. Furthermore, while ensuring the conductivity and dispersibility of the expandable graphite, the flake graphite dispersion is used for hole metallization of PCB boards. The expandable graphite in the flake graphite dispersion is Only a small amount of graphite is stacked and attached to the hole wall of the PCB board. After further rapid heating, a conductive layer with a certain thickness, continuous and uniform appearance, and good conductivity can be quickly attached to the hole wall of the PCB board. The grinding particle size D50 of the expandable graphite is set to 0.5μm to 0.8μm. The surfactant and dispersant are added to the expandable graphite for grinding and dispersion, which effectively achieves uniform and stable dispersion of the expandable graphite, better ensures conductivity and dispersibility, and thus realizes the rapid formation of a certain thickness, continuous and uniform conductive layer on the hole wall of the PCB board. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a flow chart of a method for preparing a flake graphite dispersion according to one embodiment of the present invention;

[0028] Figure 2 It is a structural diagram of a crushing stripper;

[0029] Figure 3 for Figure 2 Another structural schematic diagram of the crushing stripper shown;

[0030] Figure 4 for Figure 2 Another structural schematic diagram of the crushing stripper shown;

[0031] Figure 5 for Figure 4 A cross-sectional view of the crushing stripper along line AA';

[0032] Figure 6 for Figure 4 A partial cross-sectional view of the crushing stripper along BB';

[0033] Figure 7 for Figure 6 A partial enlarged view of the crushing stripper at point A shown;

[0034] Figure 8 for Figure 6 A partial enlarged view of the B portion of the crushing stripper shown;

[0035] Figure 9 for Figure 6 A partial enlarged view of point C of the crushing stripper shown. DETAILED DESCRIPTION

[0036] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0037] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] The present application provides a method for preparing a flake graphite dispersion. The method comprises the following steps: obtaining the following components of the flake graphite dispersion: natural graphite, a surfactant, a dispersant, and a thickener; acid-treating the natural graphite to obtain expandable graphite; adding the surfactant and dispersant to the expandable graphite and performing a cooling and grinding operation to obtain a ground product, wherein the expandable graphite in the ground product has a particle size D50 of 0.5 μm to 0.8 μm; and adding the thickener to the ground product and mixing the mixture to obtain the flake graphite dispersion.

[0040] The above-mentioned method for preparing the flake graphite dispersion uses natural graphite, a surfactant, a dispersant and a thickener to prepare the flake graphite dispersion, which has low pollution. The natural graphite is further acid-treated to form a graphite intercalation compound formed by inserting sulfuric acid molecules or nitric acid molecules between the layers of the natural graphite, namely expandable graphite. When the natural graphite layers are rapidly heated, the interlayers of the natural graphite expand to obtain a graphite with a honeycomb structure. In addition, while ensuring the conductivity and dispersibility of the expandable graphite, the flake graphite dispersion is used for hole metallization of PCB boards. The expandable graphite in the flake graphite dispersion is Only a small amount of graphite is stacked and attached to the hole wall of the PCB board. After further rapid heating, a conductive layer with a certain thickness, continuous and uniform appearance, and good conductivity can be quickly attached to the hole wall of the PCB board. The grinding particle size D50 of the expandable graphite is set to 0.5μm to 0.8μm. The surfactant and dispersant are added to the expandable graphite for grinding and dispersion, which effectively achieves uniform and stable dispersion of the expandable graphite, better ensures conductivity and dispersibility, and thus realizes the rapid formation of a certain thickness, continuous and uniform conductive layer on the hole wall of the PCB board.

[0041] In order to better understand the preparation method of the flake graphite dispersion of the present application, the preparation method of the flake graphite dispersion of the present application is further explained below:

[0042] See also Figure 1 A method for preparing a flake graphite dispersion according to one embodiment comprises the following steps:

[0043] S100, obtaining the following components of a flake graphite dispersion: natural graphite, a surfactant, a dispersant, and a thickener. It can be understood that graphene has poor dispersibility in water and a small particle size, which makes it very easy for graphene to agglomerate in water and causes the particle size to increase unevenly. It is still difficult to improve the dispersion uniformity and stability of graphene simply by adding various additives. If the graphene is modified, although the problem of poor hydrophilicity of graphene is fundamentally solved, it also forces the conductivity of graphene to deteriorate, just like graphene oxide. Therefore, it is necessary to repeatedly attach it to the PCB board to form a thicker conductive layer on the hole wall of the PCB board to ensure the subsequent electroplating. This will cause the hole metallization efficiency of the PCB board to decrease. Therefore, in the present application, natural graphite, surfactant, dispersant and thickener are directly obtained to prepare the sheet decorative film dispersion. Among them, natural graphite is conducive to the formation of expandable graphite, and further the expandable graphite is used in conjunction with the surfactant, dispersant and thickener, which better ensures the dispersion uniformity and stability of the expandable graphite. S200: Acid-treating the natural graphite to obtain expandable graphite. It is understood that acid-treating the natural graphite involves reacting the natural graphite with an oxidant such as hydrogen peroxide, potassium permanganate, or perchlorate in the presence of concentrated sulfuric acid or concentrated nitric acid, thereby inserting sulfuric acid or nitric acid molecules between the interlayers of the natural graphite to form a graphite intercalation compound, i.e., expandable graphite. Upon rapid heating, the interlayers of the natural graphite expand, resulting in a honeycomb-structured graphite. This allows only a small amount of expandable graphite to be stacked and attached to the pore walls of the PCB. Further rapid heating rapidly forms a continuous, uniform, and non-exposed conductive layer of good conductivity with a predetermined thickness on the pore walls of the PCB.

[0044] S300, adding a surfactant and a dispersant to the expandable graphite and performing a cooling and grinding operation to obtain a grind, wherein the particle size D50 of the expandable graphite in the grind is 0.5μm to 0.8μm. It is understandable that if the expandable graphite expands before being attached to the hole wall of the PCB board, it will cause the expandable graphite to be unable to be attached to the hole wall of the PCB board by only a small amount of stacking. Even if there is a small amount of blank space for attachment at this time, further rapid heating can quickly make the hole wall of the PCB board adhere to a layer of a certain thickness and continuous, uniform, and non-exposed conductive layer with good conductivity. Therefore, in this application, when crushing and grinding natural graphite, it is controlled to be carried out at a low temperature to reduce the expansion of the expandable graphite; in addition, since the expandable graphite Expanded graphite can fill the blank space on the hole wall of the PCB board when attached by expansion, so that the particle size of the expandable graphite is not very demanding. It is only necessary to make the grinding particle size D50 of the expandable graphite 0.5μm to 0.8μm. Compared with the particle size of graphene, the agglomeration severity of the expandable graphite is also reduced to a certain extent. In addition, the surfactant and dispersant are added to the expandable graphite for grinding and dispersion, thereby achieving better uniform and stable dispersion of the expandable graphite, and better ensuring conductivity and dispersibility.

[0045] S400: Adding a thickener to the ground material and mixing the mixture to obtain a flake graphite dispersion. It is understood that the preparation of the flake graphite dispersion only uses natural graphite, a surfactant, a dispersant, and a thickener, which are non-toxic to the human body and have low pollution.

[0046] The above-mentioned method for preparing the flake graphite dispersion uses natural graphite, a surfactant, a dispersant and a thickener to prepare the flake graphite dispersion, which has low pollution. The natural graphite is further acid-treated to form a graphite intercalation compound formed by inserting sulfuric acid molecules or nitric acid molecules between the layers of the natural graphite, namely expandable graphite. When the natural graphite layers are rapidly heated, the interlayers of the natural graphite expand to obtain a graphite with a honeycomb structure. In addition, while ensuring the conductivity and dispersibility of the expandable graphite, the flake graphite dispersion is used for hole metallization of PCB boards. The expandable graphite in the flake graphite dispersion is Only a small amount of graphite is stacked and attached to the hole wall of the PCB board. After further rapid heating, a conductive layer with a certain thickness, continuous and uniform appearance, and good conductivity can be quickly attached to the hole wall of the PCB board. The grinding particle size D50 of the expandable graphite is set to 0.5μm to 0.8μm. The surfactant and dispersant are added to the expandable graphite for grinding and dispersion, which effectively achieves uniform and stable dispersion of the expandable graphite, better ensures conductivity and dispersibility, and thus realizes the rapid formation of a certain thickness, continuous and uniform conductive layer on the hole wall of the PCB board.

[0047] In one embodiment, a surfactant and a dispersant are added to expandable graphite and subjected to a cooling and grinding operation, which specifically includes the following steps:

[0048] adding a surfactant, a dispersant and expandable graphite into a dispersion medium and performing a wetting and stirring operation to obtain a wetted mixture;

[0049] The wet mixture is added to a crusher and subjected to cryogenic grinding.

[0050] In one embodiment, the wet mixture is added to a crusher and subjected to cryogenic grinding, and the rotation speed of the crusher is 50 rpm to 100 rpm.

[0051] In one embodiment, the dispersion medium is deionized water.

[0052] In one embodiment, the dispersion medium includes deionized water and N-methylpyrrolidone. It is understood that the combination of deionized water and N-methylpyrrolidone as the dispersion medium to wet the expanded graphite and then grind it is conducive to the exfoliation of the expanded graphite.

[0053] In one embodiment, the volume ratio of deionized water to N-methylpyrrolidone is 1:(0.05-0.3).

[0054] In one embodiment, the temperature of adding the wet mixture to the crushing stripper for cryogenic grinding is 2°C to 8°C.

[0055] In one embodiment, the surfactant is sodium lauryl sulfate and / or alkylphenol polyoxyethylene ether. It is understood that sodium lauryl sulfate and alkylphenol polyoxyethylene ether, when combined with expanded graphite, can act as coupling agents, exhibiting a certain surface modification effect, improving the fluidity of the expanded graphite during grinding, and effectively reducing or even preventing agglomeration of the expanded graphite, thereby effectively improving the dispersibility, wettability, and stability of the expanded graphite.

[0056] In one embodiment, the dispersant is polyvinylpyrrolidone.

[0057] In one embodiment, the thickener is sodium carboxymethylcellulose or ethylene-acrylic acid copolymer. As will be appreciated, sodium carboxymethylcellulose or ethylene-acrylic acid copolymer exhibits high viscosity at static and low shear rates. This reduces the free space for expanded graphite particles, thereby increasing the viscosity of the expanded graphite dispersion, thereby significantly improving the dispersion stability of the expanded graphite. At high shear rates, the molecules align parallel to the flow direction, reducing viscosity and facilitating adhesion to the PCB hole walls. This effectively ensures the rapid formation of a continuous and uniform conductive layer of a certain thickness on the PCB hole walls.

[0058] In one embodiment, a surfactant, a dispersant and expandable graphite are added to a portion of the dispersion medium to perform a wetting and stirring operation.

[0059] In one embodiment, the thickener and the remaining dispersion medium are added to the ground material and mixed.

[0060] Please also refer to Figure 2 and Figure 3 In one embodiment, the crushing and stripping device 10 includes a mounting seat 200, a power mechanism 100 and a crushing and stripping tank 300, the crushing and stripping tank 300 includes a crushing and stripping pestle 310 and a crushing and stripping tank body 320, the power mechanism 100 and the crushing and stripping tank body 320 are both arranged on the mounting seat 200, the crushing and stripping pestle 310 is arranged in the crushing and stripping tank body 320, and one end of the crushing and stripping pestle 310 protrudes from the crushing and stripping tank body 320 and is connected to the power output of the power mechanism 100, the other end of the crushing and stripping pestle 310 is against the inner wall of the crushing and stripping tank body 320, and the crushing and stripping pestle 310 is moved by the power mechanism 100. The force mechanism 100 is rotatably connected to the crushing and stripping tank body 320. The crushing and stripping tank body 320 is supported on the inner wall of the crushing and stripping pestle 310 and is provided with a sieve hole (not shown in the figure). The extension direction of the sieve hole is the same as the thickness direction of the crushing and stripping tank body 320, and a cooling water circulation pipe 301 is opened on the inner wall of the crushing and stripping tank body 320 avoiding the sieve hole. The cooling water circulation pipe 301 is arranged near the abutment of the crushing and stripping tank body 320 and the crushing and stripping pestle 310, and the cooling water circulation pipe 301 is arranged on the periphery of the sieve hole, which better realizes the sufficient grinding of the dispersant, surfactant and expandable graphite under low temperature conditions.

[0061] It can be understood that, generally speaking, the grinding media and the grinding chamber wall play a role in the grinding structure. That is, taking the present application as an example, the main structure that plays a grinding role in the crushing and stripping tank 300 is the inner wall of the crushing and stripping tank body 320 and the crushing and stripping pestle 310 that abut against the crushing and stripping pestle 310. Specifically, the crushing and stripping pestle 310 is used to utilize the extrusion friction between the crushing and stripping pestle 310 and the inner wall of the crushing and stripping tank body 320 to achieve the grinding and mixing of expandable graphite and other materials, thereby making the part of the crushing and stripping tank body 320 that abuts against the crushing and stripping pestle 310 need to have good structural strength, otherwise it will cause the grinding effect of the expandable graphite to be poor, and And it will affect the service life of the crushing and stripping tank 300. That is to say, the sieve holes on the inner wall of the crushing and stripping tank body 320 have a large hole depth. In this way, the crushing and stripping pestle 310 has a large extrusion force on the inner wall of the crushing and stripping tank body 320, so that the expandable graphite with a particle size slightly larger than the sieve hole or a particle size consistent with the sieve hole is directly squeezed into the sieve hole. Since the depth of the sieve hole is large, it is easy to cause the sieve hole to be blocked. Furthermore, in order to achieve sufficient grinding and mixing of materials such as expandable graphite, the expandable graphite is generally ground to the required particle size in the crushing chamber before passing through the sieve hole. At this time, there will be a large number of expandable graphite particles with a particle size close to the sieve hole, which further deepens the problem of clogging the sieve hole. Therefore, the present application makes one embodiment of the invention, the crushing and stripping tank body 320 is provided with a crushing chamber 302, a stripping chamber 303 and a storage chamber 304, and the crushing and stripping pestle 310 is arranged in the crushing chamber 302, and one end of the crushing and stripping pestle 310 protrudes from the crushing chamber 302 and is connected to the power output end of the power mechanism 100, and the other end of the crushing and stripping pestle 310 is against the cavity wall of the crushing chamber 302, and the sieve hole is provided in the crushing chamber 302 for abutting the cavity wall of the crushing and stripping pestle 310, and the sieve hole is provided in the crushing chamber 302 for abutting the cavity wall of the crushing and stripping pestle 310. The extension direction of the hole intersects with the thickness direction of the cavity wall of the crushing cavity 302, the sieving hole is connected with the stripping cavity 303, and a circulation hole 305 is also provided on the cavity wall of the crushing cavity 302. The circulation hole 305 is respectively connected with the crushing cavity 302 and the stripping cavity 303. The aperture of the circulation hole 305 is greater than or equal to the aperture of the sieving hole. The stripping cavity 303 is connected with a blower (not shown in the figure), and a target object sieve hole (not shown in the figure) is provided on the cavity wall of the stripping cavity 303 away from the crushing cavity 302. The extension direction of the target object sieve hole intersects with the thickness direction of the cavity wall of the stripping cavity 303, and the stripping cavity 303 is connected with the storage cavity 304 through the target object sieve hole.It can be understood that the portion of the crushing and stripping tank 300 that is subjected to a greater extrusion force, that is, the portion of the crushing chamber 302 that is used to abut against the crushing and stripping pestle 310, has a larger aperture of the sieve hole, which effectively reduces the problem of clogging of the sieve hole. Furthermore, the expandable graphite sieved out through the sieve hole in the stripping chamber 303 can be further gradually guided back to the crushing chamber 302 through the blower for grinding, which reduces the influence of the doping of expandable graphite with smaller particle size on the overall grinding effect of the expandable graphite, and achieves the reduction of the problem of clogging of the expandable graphite, thereby better ensuring the grinding effect and grinding smoothness of materials such as expandable graphite.

[0062] It is understandable that although the expandable graphite in the crushing and stripping tank 320 can be further ground after the sieve hole is blocked, due to the reduction in the particle size of some expandable graphite, the expandable graphite with smaller particle size will be more filled in the gaps between the expandable graphite with larger particle size, thereby affecting the further crushing and grinding of the expandable graphite, that is, it will affect the further sufficient grinding and mixing of materials such as expandable graphite. Therefore, in this application, the sieve hole is connected to the stripping chamber 303, and a circulation hole 305 is also opened on the cavity wall of the crushing chamber 302, and the circulation hole 305 is respectively connected to the crushing chamber 302 and the stripping chamber 303, and the aperture of the circulation hole 305 is greater than or equal to the sieve hole. The stripping chamber 303 is connected to the blower, and a target sieve hole is provided on the wall of the stripping chamber 303 on the side away from the crushing chamber 302. The stripping chamber 303 is connected to the storage chamber 304 through the target sieve hole, so that the sieve hole provided at the part of the crushing chamber 302 that abuts against the crushing stripping pestle 310 has a larger aperture, which effectively reduces the problem of clogging of the sieve hole. Furthermore, the expandable graphite and other substances sieved out through the sieve hole in the stripping chamber 303 can be further gradually guided back to the crushing chamber 302 through the blower for grinding, which effectively reduces the influence of the doping of expandable graphite with smaller particle size on the overall grinding effect of the expandable graphite.

[0063] Please also refer to Figures 3 to 6 In one embodiment, the crushing and stripping tank body 320 includes a feeding part 321 and a crushing and stripping part 322. The feeding part 321 is connected to the crushing and stripping part 322 to form a crushing chamber 302. The stripping chamber 303 and the storage chamber 304 are opened in the crushing and stripping part 322. The crushing and stripping part 322 is set on the mounting seat 200, and the cooling water circulation pipe 301 is opened in the feeding part 321.

[0064] In one embodiment, the feeding part and the crushing and stripping part are screwed together to form a crushing chamber, which better realizes the convenience of maintenance and dredging when the screening holes are blocked, thereby better improving the convenience of using the crushing and stripping device.

[0065] Please also refer to Figures 3 to 6In one embodiment, the crushing and stripping unit 322 has a discharge opening 309 on a side of the storage chamber 304 away from the stripping chamber 303. Furthermore, the crushing and stripping tank 320 also includes a discharge portion 323, which covers the discharge opening 309. The peripheral edge of the discharge portion 323 is movably connected to the discharge opening 309, effectively achieving rapid removal of the ground expandable graphite and other materials from the crushing and stripping unit 322. It also facilitates maintenance and unblocking when the target object sieve holes are blocked, thereby significantly improving the ease of use of the crushing and stripping device 10.

[0066] In one embodiment, the discharge portion is screwed to the crushing and stripping portion at the discharge opening, which further improves the convenience of use of the crushing and stripping device.

[0067] Please also refer to Figures 3 to 6 In one embodiment, the crushing and stripping tank body 320 further includes a sealing ring 324, which is sleeved on the periphery of the discharge portion 323, and the sealing ring 324 is clamped between the discharge portion 323 and the crushing and stripping portion 322 when the discharge portion 323 is connected to the discharge opening 309, thereby better ensuring the sealing of the discharge opening 309 on the crushing and stripping tank body 320, thereby reducing the leakage of substances such as expandable graphite and ensuring the grinding yield of the expandable graphite.

[0068] Please also refer to Figures 5 to 9In one embodiment, the crushing and stripping pestle 310 includes a linkage portion 311, a crushing and stripping pestle body 312, and a clamping portion 313. One end of the linkage portion 311 is located in the crushing chamber 302, and the other end of the linkage portion 311 is connected to the power output end of the power mechanism 100. The linkage portion 311 is rotatably connected to the crushing and stripping tank 320 through the power mechanism 100. The end of the linkage portion 311 away from the power mechanism 100 is provided with a hollow sliding groove 307 and a clamping sliding hole 308 connected thereto. The extension of the hollow sliding groove 307 The direction is the same as the extension direction of the linkage part 311, the crushing and stripping pestle body 312 is arranged at the hollow sliding groove 307 and is slidably connected to the linkage part 311, the extension direction of the clamping part 313 intersects with the extension direction of the crushing and stripping pestle body 312, the clamping part 313 is passed through one end of the crushing and stripping pestle body 312 close to the linkage part 311, and the clamping part 313 is clamped in the clamping slide hole 308 and is slidably connected to the linkage part 311, and the clamping part 313 slides at the clamping slide hole 308 in the direction away from or close to the power mechanism 100. The worm gear 310 is provided with a plurality of worm gears 320, and the worm gear 311 is provided with a plurality of worm gears 321, 322 and 323, and the worm gear 312 is provided with a plurality of worm gears 322, and the worm gear 313 is provided with a plurality of worm gears 323, 324 and 325. The cam 314 is engaged with the movable part 316 by the support 318 and the support 319, and the movable part 317 is engaged with the movable part 318 by the support 319.

[0069] Please also refer to Figures 4 to 8In one embodiment, the power mechanism 100 includes a first rotating shaft 110, a second rotating shaft 120, a motor 130 and a transmission belt 140. One end of the first rotating shaft 110 and one end of the second rotating shaft 120 are both rotatably connected to the mounting base 200. The motor 130 is installed on the mounting base 200. The power output end of the motor 130 is connected to the other end of the first rotating shaft 110, and the other end of the second rotating shaft 120 is connected to one end of the linkage part 311 protruding from the crushing chamber 302. The transmission belt 140 is sleeved on the first rotating shaft 110 and the second rotating shaft 120, which better realizes the effective rotation of the crushing and stripping pestle body 312 compared to the wall of the crushing chamber 302, thereby better ensuring the grinding efficiency of the crushing and stripping tank 300.

[0070] Please also refer to Figures 5 to 9In one embodiment, the power mechanism 100 further includes a cylinder 150 and a lifting member 160. The cylinder 150 is mounted on the mounting base 200, and the power output end of the cylinder 150 is connected to the lifting member 160. The lifting member 160 slides toward or away from the crushing chamber 302 through the cylinder 150. One end of the first rotating shaft 110 and one end of the second rotating shaft 120 are both rotatably connected to the lifting member 160. Further, the cylinder 150 includes a cylinder body 151 and a connecting rod 152. The cylinder body 151 is mounted on the mounting base 200. The power output end of the cylinder body 151 is connected to one end of the connecting rod 152. The other end of the connecting rod 152 is provided with a central clamping groove 3010. The extension direction of the central clamping groove 3010 is the same as the extension direction of the connecting rod 152. The first rotating shaft 110 is clamped in the central clamping groove 3010, and the first rotating shaft 110 is at The central engaging groove 3010 is slidably connected to the connecting rod 152. When the cylinder 150 drives the lifting member 160 toward the crushing chamber 302, the first rotating shaft 110 moves toward the cylinder body 151 at the central engaging groove 3010. When the cylinder 150 drives the lifting member 160 toward the crushing chamber 302, the first rotating shaft 110 moves away from the cylinder body 151 at the central engaging groove 3010. Furthermore, when the cylinder 150 drives the lifting member 160 toward the crushing chamber 302, the second rotating shaft 120 drives the linkage portion 311 toward the crushing and stripping pestle portion 312. The crushing and stripping pestle portion 312 slides into the hollow sliding groove 307 and is held against the bottom of the hollow sliding groove 307, and / or the holding portion 313 is held against the wall of the holding sliding hole 308.It can be understood that in order to better achieve the rapid entry of expandable graphite with larger particle size into the grinding range of the crushing and stripping pestle 310, the crushing and stripping pestle 310 can be moved in the direction close to and away from the power mechanism 100 in the direction of gravity, which will cause the crushing and stripping pestle 310 to exert a smaller extrusion force on the cavity wall of the crushing cavity 302, that is, the extrusion force is only the weight of the crushing and stripping pestle 310 itself. In this way, although the expandable graphite with larger particle size can be quickly entered into the crushing and stripping pestle 310 grinding range, but will cause the crushing and stripping pestle 310 to grind and mix the expandable graphite and other materials with a weak force, and thus still cause the grinding and mixing efficiency of the expandable graphite and other materials to be poor. Therefore, in the present application, based on the crushing and stripping pestle 310 being movable in the direction of gravity, the extension direction of the middle-through card slot 3010 is further made to be the same as the extension direction of the connecting rod 152, the first rotating shaft 110 is clamped in the middle-through card slot 3010, and the first rotating shaft 110 is at the middle-through card slot 3010. The second rotating shaft 120 is slidably connected to the connecting rod 152. Further, when the cylinder 150 drives the lifting member 160 to move toward the crushing chamber 302, the second rotating shaft 120 drives the linkage part 311 to move toward the crushing and stripping pestle body 312. The crushing and stripping pestle body 312 slides into the hollow sliding groove 307 and is held at the bottom of the hollow sliding groove 307, and / or the holding part 313 is held at the wall of the holding sliding hole 308, that is, the cylinder 150 and the lifting member 160 drive the linkage part 311 to flexibly crush and strip. The pressure of the pestle body 312 is released, so that the crushing and stripping pestle body 312 can maneuverably exert a greater squeezing effect on the wall of the crushing chamber 302, thereby achieving the grinding strength of the crushing and stripping pestle 310. In other words, the motor 130 and the cylinder 150 cooperate with the overall structure of the crushing and stripping tank 300 to effectively complete the intermittent rapid entry of large particles of expandable graphite and the intermittent and sufficient mixing and grinding of substances such as expandable graphite, thereby effectively improving the mixing and grinding efficiency of substances such as expandable graphite.

[0071] It can be understood that a central connecting groove 3010 is provided at the other end of the connecting rod 152, and the extension direction of the central connecting groove 3010 is the same as the extension direction of the connecting rod 152. The first rotating shaft 110 is clamped in the central connecting groove 3010, and the first rotating shaft 110 is slidingly connected to the connecting rod 152 at the central connecting groove 3010, so that the cylinder body 151 only lifts the crushing and stripping pestle 310, the first rotating shaft 110, the second rotating shaft 120 and the transmission belt 140, and the lifting and rotation of the crushing and stripping pestle 310 are non-interference, the structure is simple, and the load of the cylinder is small, which effectively reduces the loss of each structure of the crushing and stripping device 10, thereby improving the service life of the crushing and stripping device 10.

[0072] Please also refer to Figures 5 to 9In one embodiment, a buffer pad 340 is provided on the linkage part 311. When the lifting member 160 is moved away from the crushing and stripping pestle body 312 by the cylinder body 151 to the farthest point, the buffer pad 340 abuts against the side of the mounting seat 200 away from the cylinder body 151. That is, when the cylinder body 151 drives the lifting member 160 to move away from the crushing and stripping pestle body 312 to the maximum distance between the lifting member 160 and the crushing and stripping pestle body 312, the buffer pad 340 abuts against the side of the mounting seat 200 away from the cylinder body 151, thereby generating mechanical interference and preventing the cylinder body 151 from further retracting due to inertia, reducing the wear of the cylinder body 151, and thus better improving the service life of the crushing and stripping device 10.

[0073] Please also refer to Figures 5 to 9 In one embodiment, the crushing and stripping pestle body 312 and the clamping part 313 are an integrally formed structure, which greatly improves the connection stability and compactness of the crushing and stripping pestle body 312 and the clamping part 313, thereby better improving the clamping stability of the crushing and stripping pestle body 312 on the linkage part 311 in the horizontal direction, thereby better ensuring the rotational grinding effect of the crushing and stripping pestle body 312.

[0074] Please also refer to Figures 5 to 9 In one embodiment, the first rotating shaft 110 is rotatably connected to the lifting member 160 through the first bearing 170. Specifically, the first rotating shaft 110 is connected to the inner ring of the first bearing 170, and the mounting seat 200 is connected to the outer ring of the first bearing 170.

[0075] Please also refer to Figures 5 to 9 In one embodiment, the second rotating shaft 120 is connected to the lifting member 160 through the second bearing 180. Specifically, the second rotating shaft 120 is connected to the inner ring of the second bearing 180, and the mounting seat 200 is connected to the outer ring of the second bearing 180.

[0076] Please also refer to Figures 5 to 9 In one embodiment, the first rotating shaft 110 includes a first rotating roller 111, a second rotating roller 112 and a rotating wheel 113. The first rotating roller 111 and the second rotating roller 112 are connected, and the rotating wheel 113 is sleeved at the connection between the first rotating roller 111 and the second rotating roller 112. The first rotating roller 111 is rotatably connected to the lifting member 160. The second rotating roller 112 is a prism. The outer periphery of the second rotating roller 112 abuts against the groove wall of the middle-through clamping groove 3010, and the second rotating roller 112 is slidably connected to the connecting rod 152 at the middle-through clamping groove 3010. The second rotating roller 112 moves toward or away from the cylinder body 151 through the lifting member 160, which better ensures the rotation and grinding effect of the crushing and peeling pestle body 312.

[0077] In one embodiment, the inner diameter of the circulation hole is larger than the inner diameter of the screening hole, and a primary screen is provided at the circulation hole, and the primary screen is movably connected to the crushing and stripping part. The inner diameter of the mesh of the primary screen is greater than or equal to the inner diameter of the screening hole, which better ensures that the hole blockage problem during the grinding process of the expandable graphite is reduced, and thus better ensures the grinding efficiency of the expandable graphite.

[0078] In one embodiment, the primary screen is detachably connected to the crushing and stripping part, which better realizes the convenience of maintenance and dredging when the screening holes are blocked, thereby better improving the convenience of using the crushing and stripping device.

[0079] In one embodiment, the primary screen is detachably adhered to the crushing and stripping part, which further improves the convenience of maintenance and dredging when the screening holes are blocked, thereby improving the ease of use of the crushing and stripping device.

[0080] Please also refer to Figures 5 to 9 In one embodiment, a fixing ring 210 is connected to the mounting seat 200. The fixing ring 210 is sleeved on the periphery of the crushing and stripping portion 322 and abuts against the crushing and stripping portion 322, thereby better ensuring the placement stability of the crushing and stripping portion 322 on the mounting seat 200, thereby better ensuring the grinding stability.

[0081] In one embodiment, the fixing ring and the mounting seat are integrally formed, which further ensures the stability of the crushing and stripping portion on the mounting seat.

[0082] In one embodiment, a fine screen is provided at the target object sieve hole, and the periphery of the fine screen is movably connected to the crushing and stripping part, which better realizes the convenience of maintenance and unblocking when the target object sieve hole is blocked, thereby better improving the convenience of use of the crushing and stripping device.

[0083] In one embodiment, the target object sieve hole is detachably connected to the crushing and stripping part, which further improves the convenience of maintenance and unblocking when the target object sieve hole is blocked, thereby improving the convenience of use of the crushing and stripping device.

[0084] In one embodiment, the fine screen is detachably adhered to the crushing and stripping part, which further improves the convenience of maintenance and unblocking when the screen holes of the target object are blocked, thereby improving the ease of use of the crushing and stripping device.

[0085] The present application also provides a flake graphite dispersion, which is prepared by the method for preparing a flake graphite dispersion of any of the above embodiments. The flake graphite dispersion also includes a defoaming agent and a pH regulator.

[0086] In one embodiment, the defoaming agent is a silicone oil cream. It should be noted that the main component of the silicone oil cream is dimethyl silicone oil.

[0087] In one embodiment, the pH adjuster is sodium carbonate.

[0088] In one embodiment, the flake graphite dispersion includes the following components in parts by weight: 0.5 to 3 parts of natural graphite, 0.1 to 1.5 parts of a surfactant, 0.2 to 2 parts of a dispersant, 0.01 to 0.15 parts of a thickener, and 86 to 95 parts of a dispersion medium.

[0089] In one embodiment, the flake graphite dispersion further comprises the following components in parts by weight: 0.01 to 0.15 parts of a pH adjuster and 0.01 to 0.15 parts of a defoaming agent.

[0090] The present application also provides an application of a flake graphite dispersion, wherein the flake graphite dispersion of any of the above embodiments is used for hole metallization of a PCB board.

[0091] Compared with the prior art, the present invention has at least the following advantages:

[0092] The method for preparing a flake graphite dispersion of the present invention uses natural graphite, a surfactant, a dispersant, and a thickener to prepare the flake graphite dispersion, which has low pollution. The natural graphite is further acid-treated to insert sulfuric acid molecules or nitric acid molecules into the interlayers of the natural graphite to form a graphite intercalation compound, namely, expandable graphite. When the interlayers of the natural graphite are rapidly heated, the interlayers of the natural graphite expand to obtain graphite with a honeycomb structure. Furthermore, while ensuring the conductivity and dispersibility of the expandable graphite, the flake graphite dispersion is used for hole metallization of PCB boards. The expandable graphite in the flake graphite dispersion is Only a small amount of graphite is stacked and attached to the hole wall of the PCB board. After further rapid heating, a conductive layer with a certain thickness, continuous and uniform appearance, and good conductivity can be quickly attached to the hole wall of the PCB board. The grinding particle size D50 of the expandable graphite is set to 0.5μm to 0.8μm. The surfactant and dispersant are added to the expandable graphite for grinding and dispersion, which effectively achieves uniform and stable dispersion of the expandable graphite, better ensures conductivity and dispersibility, and thus realizes the rapid formation of a certain thickness, continuous and uniform conductive layer on the hole wall of the PCB board.

[0093] The following examples illustrate some specific embodiments, where percentages are expressed by weight. It should be noted that the following examples do not exhaust all possible situations, and that the materials used in the following examples, unless otherwise specified, can be obtained from commercial sources.

[0094] Example 1

[0095] Preparation of natural graphite: After grinding natural graphite into an average particle size of 35.43±2μm, 5kg of the ground natural graphite is weighed into a 250ml beaker, 1ml of hydrogen peroxide is added to the natural graphite, and then 12ml of fuming nitric acid is added. The mixture is rapidly stirred in an ice-water bath until the reaction is slow. The reaction system is kept at a constant temperature of 25°C. After the oxidation reaction for 60 minutes, the mixture is washed with a 35% nitric acid solution, filtered, and 5ml of glacial acetic acid solution is added dropwise with continuous stirring. After the reaction for 60 minutes, the mixture is washed with water, filtered, and dried at 65°C for 10 hours to obtain sulfur-free and ash-free expandable graphite.

[0096] Raw materials: 1kg expandable graphite, 0.3kg polyvinyl pyrrolidone, 0.08kg alkylphenol polyoxyethylene ether, 0.08kg sodium lauryl sulfate, 0.01kg sodium carboxymethyl cellulose, 0.01kg silicone oil cream, 0.01kg sodium carbonate, 4.3kg N-methylpyrrolidone and 85kg deionized water;

[0097] Equipment: Crusher and stripper;

[0098] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 0.5kg deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 50rpm. After the solid material is completely ground and the particle size D50 is 0.5μm, take it out and add the remaining deionized water to stir and mix.

[0099] Example 2

[0100] Preparation of natural graphite: same as in Example 1;

[0101] Raw materials: 1 kg expandable graphite, 0.3 kg polyvinyl pyrrolidone, 0.16 kg alkylphenol polyoxyethylene ether, 0.01 kg sodium carboxymethyl cellulose, 0.01 kg silicone oil cream, 0.01 kg sodium carbonate, 4.3 kg N-methyl pyrrolidone and 85 kg deionized water;

[0102] Equipment: Crusher and stripper;

[0103] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 0.5kg deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 50rpm. After the solid material is completely ground and the particle size D50 is 0.5μm, take it out and add the remaining deionized water to stir and mix.

[0104] Example 3

[0105] Preparation of natural graphite: same as in Example 1;

[0106] Raw materials: 1 kg expandable graphite, 0.3 kg polyvinyl pyrrolidone, 0.16 kg sodium lauryl sulfate, 0.01 kg sodium carboxymethyl cellulose, 0.01 kg silicone oil cream, 0.01 kg sodium carbonate, 4.3 kg N-methyl pyrrolidone and 90 kg deionized water;

[0107] Equipment: Crusher and stripper;

[0108] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 0.5kg deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 50rpm. After the solid material is completely ground and the particle size D50 is 0.5μm, take it out and add the remaining deionized water to stir and mix.

[0109] Example 4

[0110] Preparation of natural graphite: same as in Example 1;

[0111] Raw materials: 1kg expandable graphite, 0.3kg polyvinyl pyrrolidone, 0.16kg alkylphenol polyoxyethylene ether, 0.01kg sodium carboxymethyl cellulose, 0.01kg silicone oil cream, 0.01kg sodium carbonate and 90kg deionized water;

[0112] Equipment: Crusher and stripper;

[0113] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 0.5kg deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 50rpm. After the solid material is completely ground and the particle size D50 is 0.5μm, take it out and add the remaining deionized water to stir and mix.

[0114] Example 5

[0115] Preparation of natural graphite: same as in Example 1;

[0116] Raw materials: 1 kg expandable graphite, 0.3 kg polyvinyl pyrrolidone, 0.16 kg sodium lauryl sulfate, 0.01 kg sodium carboxymethyl cellulose, 0.01 kg silicone oil cream, 0.01 kg sodium carbonate and 90 kg deionized water;

[0117] Equipment: Crusher and stripper;

[0118] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 0.5kg deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 50rpm. After the solid material is completely ground and the particle size D50 is 0.5μm, take it out and add the remaining deionized water to stir and mix.

[0119] Example 6

[0120] Preparation of natural graphite: same as in Example 1;

[0121] Raw materials: 1 kg expandable graphite, 0.3 kg polyvinyl pyrrolidone, 0.08 kg alkylphenol polyoxyethylene ether, 0.08 kg sodium lauryl sulfate, 0.01 kg ethylene-acrylic acid copolymer, 0.01 kg silicone oil cream, 0.01 kg sodium carbonate, 4.3 kg N-methylpyrrolidone and 85 kg deionized water;

[0122] Equipment: Crusher and stripper;

[0123] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 0.5kg deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 50rpm. After the solid material is completely ground and the particle size D50 is 0.5μm, take it out and add the remaining deionized water to stir and mix.

[0124] Example 7

[0125] Preparation of natural graphite: same as in Example 1;

[0126] Raw materials: expandable graphite 1kg, polyvinyl pyrrolidone 0.3kg, alkylphenol polyoxyethylene ether 0.08kg, sodium lauryl sulfate 0.08kg, ethylene-acrylic acid copolymer 0.01kg, silicone oil cream 0.01kg, sodium carbonate 0.01kg, N-methylpyrrolidone 20kg and deionized water 75kg;

[0127] Equipment: Crusher and stripper;

[0128] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 0.5kg deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 50rpm. After the solid material is completely ground and the particle size D50 is 0.5μm, take it out and add the remaining deionized water to stir and mix.

[0129] Example 8

[0130] Preparation of natural graphite: same as in Example 1;

[0131] Raw materials: expandable graphite 0.5kg, polyvinyl pyrrolidone 0.1kg, alkylphenol polyoxyethylene ether 0.02kg, sodium lauryl sulfate 0.01kg, ethylene-acrylic acid copolymer 0.01kg, silicone oil cream 0.01kg, sodium carbonate 0.01kg and deionized water 86kg;

[0132] Equipment: Crusher and stripper;

[0133] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 0.2kg deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 60rpm. After the solid material is completely ground, the particle size D50 is 0.6μm. Take it out and add the remaining deionized water to stir and mix.

[0134] Example 9

[0135] Preparation of natural graphite: same as in Example 1;

[0136] Raw materials: 2kg expandable graphite, 1kg polyvinyl pyrrolidone, 1kg alkylphenol polyoxyethylene ether, 0.1kg ethylene-acrylic acid copolymer, 0.1kg silicone oil cream, 0.1kg sodium carbonate and 92kg deionized water;

[0137] Equipment: Crusher and stripper;

[0138] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 1kg of deionized water and stir to wet thoroughly, then add them into a crusher and crush and peel at a speed of 80rpm. After the solid material is completely ground, the particle size D50 is 0.7μm. Take it out and add the remaining deionized water to stir and mix.

[0139] Example 10

[0140] Preparation of natural graphite: same as in Example 1;

[0141] Raw materials: 3kg expandable graphite, 1.5kg polyvinyl pyrrolidone, 2kg sodium lauryl sulfate, 0.15kg ethylene-acrylic acid copolymer, 0.15kg silicone oil cream, 0.15kg sodium carbonate and 95kg deionized water;

[0142] Equipment: Crusher and stripper;

[0143] Preparation method: add expandable graphite, polyvinyl pyrrolidone and alkylphenol polyoxyethylene ether into 2kg deionized water, stir and wet them thoroughly, add them into a crusher and crush and peel them at a speed of 100rpm. After the solid material is completely ground, the particle size D50 is 0.8μm. Take it out and add the remaining deionized water to stir and mix.

[0144] The flaky graphite dispersions of Examples 1 to 10, the commercially available graphite eclipse solution of Comparative Example 1, and the commercially available graphite black shadow solution of Comparative Example 2 were subjected to a PCB board Hall cell test, and the results of the on-resistance test and stability test of the PCB board after hole metallization were compared to specifically characterize the hole metallization effect and stability of the flaky graphite dispersions of Examples 1 to 10. The specific test results are shown in Table 1:

[0145] Table 1: Test results of on-resistance and stability of PCB board after hole metallization

[0146]

[0147] As shown in Table 1, the on-resistance values of the PCB boards of Examples 1-10 of the present invention after hole metallization were superior to those of the commercially available graphite etchant liquid (Comparative Example 1) and the commercially available graphite shadow liquid (Comparative Example 2), which had corresponding resistance values of 310.1Ω and 562.0Ω, respectively. In particular, the on-resistance value of the PCB board of Example 1 after hole metallization was 7.2Ω. Therefore, Examples 1-10 of the present invention have superior conductivity to both Comparative Examples 1 and 2. In the stability test, the decrease in the solid content of the upper layer after 30 days showed that Examples 1-10 of the present invention exhibited excellent stability, primarily manifested by a decrease in the solid content of the upper layer of over 97% after 30 days. This is significantly superior to the decrease in the solid content of the upper layer of the commercially available graphite etchant liquid (Comparative Example 1) and the commercially available graphite shadow liquid (Comparative Example 2), which had corresponding decreases of 81.37% and 82.63%, respectively, after 30 days, for the commercially available graphite etchant liquid (Comparative Example 1) and the commercially available graphite shadow liquid (Comparative Example 2). As described above, the flake graphite dispersions of Examples 1 to 10 of the present invention have better conductivity and stability than the commercially available graphite etchant liquid (Comparative Example 1) and the commercially available graphite shadow liquid (Comparative Example 2).

[0148] The above embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An application of a flake graphite dispersion, characterized in that: Using the flake graphite dispersion for hole metallization of a PCB board; The preparation method of the flake graphite dispersion comprises the following steps: Obtaining the following components of a flake graphite dispersion: natural graphite, a surfactant, a dispersant, and a thickener; treating the natural graphite with acid to obtain expandable graphite; Adding the surfactant and dispersant to the expandable graphite and performing a cooling and grinding operation to obtain a grind, wherein the particle size D50 of the expandable graphite in the grind is 0.5 μm to 0.8 μm; The thickener is added to the ground material and mixed to obtain a flake graphite dispersion.

2. The use of the flake graphite dispersion according to claim 1, characterized in that The step of adding the surfactant and dispersant to the expandable graphite for cooling and grinding specifically comprises the following steps: adding the surfactant, dispersant and expandable graphite into a dispersion medium and performing a wetting and stirring operation to obtain a wet mixture; The wet mixture is added to a crusher stripper for cryogenic grinding.

3. The use of the flake graphite dispersion according to claim 2, characterized in that: The dispersion medium is deionized water; or The dispersion medium includes deionized water and N-methylpyrrolidone.

4. The use of the flake graphite dispersion according to claim 2, characterized in that: The temperature of adding the wet mixture into the crusher and stripper for cryogenic grinding treatment is 2°C to 8°C.

5. The use of the flake graphite dispersion according to claim 1, characterized in that: The surfactant is sodium lauryl sulfate and / or alkylphenol polyoxyethylene ether.

6. The use of the flake graphite dispersion according to claim 1, characterized in that: The dispersant is polyvinyl pyrrolidone.

7. The use of the flake graphite dispersion according to claim 1, characterized in that: The thickener is sodium carboxymethyl cellulose or ethylene-acrylic acid copolymer.

8. The use of the flake graphite dispersion according to claim 1 is characterized in that: The flake graphite dispersion further comprises a defoaming agent and a pH regulator.

9. The use of the flake graphite dispersion according to claim 8, characterized in that: The defoaming agent is silicone oil cream; and / or, The pH regulator is sodium carbonate.

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