An easily abradable high thermal conductivity insulating plugging paste, a preparation method thereof and an application thereof

Abstract

The present invention discloses an easily grindable high thermal conductivity insulating hole plugging paste, a preparation method thereof and an application thereof. The insulating hole plugging paste comprises the following components in weight percentage: 80-93 wt% of insulating and thermally conductive powder, 6-15 wt% of resin, 0.2-2 wt% of curing agent, and 0.8-3 wt% of auxiliary agent. The insulating hole plugging paste of the present invention can match boards with high Tg and low CTE, and has the characteristics of high thermal conductivity, anti-sagging and easy grindability after curing, and is particularly suitable for hole plugging on ceramic substrates, 5G high-frequency and high-power boards.

Description

Technical Field

[0001] The present invention relates to the technical field of plug hole slurries, and particularly to an easily abradable high thermal conductivity insulating plug hole slurry, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of microelectronics technology, the integration density and assembly density of electronic products have been continuously improved. As a carrier of electronic components, the integration density of PCB and the power consumption requirements of components are also getting higher and higher. Especially in the context of 5G, the requirements for heat conduction and heat dissipation of high-frequency and high-power boards are becoming more and more urgent, which all put forward higher requirements for various performances of PCB materials. Traditional plug hole slurries have small thermal conductivity, large thermal expansion coefficient, and low glass transition temperature, and it is difficult to meet the heat conduction and heat dissipation requirements of high-frequency and high-power boards under 5G conditions.

[0003] Plug hole slurry is a material that fills PCB vias and buried vias through a resin plug hole process, and it is highly favored in PCB products with high layers and large thickness. The plug hole thermal conductive slurries on the market are mainly conductive slurries, which have a thermal conductive function. Although their thermal conductivity is relatively high, the conductive slurries have high costs and poor storage stability, and it is difficult to be widely used on PCB boards. And the fillers used in conductive slurries are generally metal powders, with relatively large thermal expansion coefficients, and they cannot match high-frequency and high-power boards.

[0004] The insulating thermal conductive plug hole slurry with ceramic powder as the filler has a small thermal expansion coefficient and low cost, and can be widely used on 5G boards. For example, the applicant's early patent CN109929220B discloses an insulating thermal conductive slurry, a preparation method thereof, and an application thereof. The insulating thermal conductive adhesive includes the following components: insulating thermal conductive powder, resin, monomer, curing agent, and additives. Through the synergistic effect of the components contained in the patent, the components are evenly dispersed, the slurry system is stable, and the storage time is long. Moreover, it has the characteristics of high insulation and high thermal conductivity and ultra-low expansion coefficient. The patent uses small particle size powder roll grinding, but the interfacial thermal resistance of this small particle size powder is large, and it is difficult to improve the thermal conductivity. That is, the thermal conductivity of the insulating thermal conductive slurry after curing in the prior art is still difficult to meet the heat conduction and heat dissipation requirements of high-frequency and high-power boards, and the phenomenon of sagging is likely to occur during the baking process, resulting in a decline in the subsequent easy abrasion performance and difficulty in meeting the production requirements. And the easy abrasion performance is a technical pain point of the slurry with ceramic powder as the filling powder, because ceramic brushes are required for grinding, the price of ceramic brushes is very high, and they are consumables. The easy abrasion characteristic can significantly reduce the grinding cost and improve the grinding efficiency.

[0005] Therefore, there is still a need to develop an insulating slurry with higher thermal conductivity, lower high-temperature thermal expansion coefficient, and easy abrasion. Summary of the Invention

[0006] To solve the problems existing in the prior art, the present invention provides an easily abradable and highly thermally conductive insulating plugging paste, which is particularly suitable for plugging holes on ceramic substrates, 5G high-frequency and high-power plates.

[0007] Another object of the present invention is to provide a preparation method of the above-mentioned easily abradable and highly thermally conductive insulating plugging paste.

[0008] Another object of the present invention is to provide an application of this easily abradable and highly thermally conductive insulating plugging paste.

[0009] To achieve the above invention objects, the present invention adopts the following technical solutions:

[0010] An easily abradable and highly thermally conductive insulating plugging paste, comprising components in the following weight percentages:

[0011] 80-93wt% insulating and thermally conductive powder;

[0012] 6-15wt% resin;

[0013] 0.2-2wt% curing agent;

[0014] 0.8-3wt% auxiliary agent.

[0015] In a specific embodiment, the insulating and thermally conductive powder is selected from at least any two of boron nitride, alumina, and aluminum nitride, preferably alumina and aluminum nitride, or alumina and boron nitride.

[0016] In a specific embodiment, the shape of the insulating and thermally conductive powder is a combination of at least any two of flaky, quasi-spherical, spherical, or angular shapes; preferably, the insulating and thermally conductive powder is spherical, quasi-spherical, or angular alumina powder and flaky boron nitride powder; more preferably, the alumina powder is alumina powder modified for the resin system, and the mass ratio of the alumina powder to the boron nitride powder is 80:1 to 10:1.

[0017] In a specific embodiment, the insulating and thermally conductive powder comprises small particle insulating and thermally conductive powder with an average particle size of 0.5-1μm and large particle insulating and thermally conductive powder with an average particle size of 10-15μm, and the maximum particle size of the insulating and thermally conductive powder does not exceed 40μm; preferably, the mass ratio of the small particle insulating and thermally conductive powder to the large particle insulating and thermally conductive powder is 5:1-50:1.

[0018] In a specific embodiment, the resin is a liquid epoxy resin without organic solvents, preferably selected from at least any one of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic epoxy resin, silicone-modified epoxy resin, and special multi-functional epoxy resin; more preferably, it is one or a combination of liquid bisphenol A epoxy resin, bisphenol F epoxy resin, or special multi-functional epoxy resin.

[0019] In a specific embodiment, the curing agent is selected from at least one of amino resin, imidazole, organic acid anhydride, dicyandiamide; preferably imidazole and dicyandiamide.

[0020] In a specific embodiment, the additives include a wetting and dispersing agent, a diluent; preferably, the wetting and dispersing agent is selected from one or a combination of two of modified polysiloxane or polyurethane compound; the diluent is an epoxy active diluent, preferably selected from one or a combination of several of monofunctional glycidyl ether or polyfunctional glycidyl ether.

[0021] On the other hand, a method for preparing the aforementioned easy-to-grind high thermal conductivity insulating plugging paste includes the following steps:

[0022] 1) Mix a certain proportion of resin, curing agent, and insulating and heat-conducting powder with a particle size not exceeding 15 μm evenly through a high-speed mixer to obtain a preliminary base material;

[0023] 2) Grind the preliminarily dispersed base material in step 1) using a three-roll mill to obtain a heat-conducting base material;

[0024] 3) Add additives and insulating and heat-conducting powder with a particle size greater than 15 μm to the heat-conducting base material in sequence, and stir evenly in a planetary stirring device to form the final easy-to-grind high thermal conductivity insulating plugging paste.

[0025] In a specific embodiment, the rotation speed of the grinding in step 2) is 200 r / min - 300 r / min, and it is sufficient to grind to a fineness of less than 15 microns; preferably, the rotation speed of the stirring in step 3) is 1500 r / min - 2000 r / min, and the duration is 2 - 5 hours.

[0026] On yet another aspect, an application of the aforementioned easy-to-grind high thermal conductivity insulating plugging paste or the easy-to-grind high thermal conductivity insulating plugging paste prepared by the aforementioned method in plugging holes on a ceramic substrate, 5G high-frequency or high-power board.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The printed circuit boards used in the 5G field are of high frequency and high power, and require plugging hole slurries with higher thermal conductivity coefficients and lower thermal expansion coefficients for matching. Moreover, in order to improve the grinding efficiency after plugging holes and reduce the consumable costs of the grinding process, the slurry needs to be easy to grind after curing. Currently, since the entire plugging hole slurry needs to be ground by a three-roll mill, powders with a particle size greater than 15 microns cannot be used in the selection of thermal conductive powders. However, the smaller-sized thermal conductive powders have a large oil absorption capacity, which easily causes the viscosity of the system to increase rapidly. And because the smaller-sized powders are more fully wrapped by the resin, the interfacial thermal resistance is large, making it difficult to improve the thermal conductivity performance.

[0029] The easy-to-grind high thermal conductive insulating plugging hole slurry provided by the present invention can achieve high thermal conductivity effects through the combination of insulating powders with different shapes and different particle sizes, and can improve the storage stability of the system and the easy-to-grind performance of the slurry after curing. First, the resin, additives, curing agent, and powders with small particle sizes are dispersed evenly to obtain a base material, and then large-particle-size powders are added and stirred evenly in a planetary mixer under vacuum to obtain a thermal conductive slurry. The preparation method provided by the present invention can not only ensure the uniform dispersion of the small-particle-size powders, but also make the entire slurry system more stable. The small-particle-size powders are uniformly ground by a three-roll mill with the resin, additives, and curing agent, which can avoid the agglomeration phenomenon of the small-particle-size powders, and better compatibility with the resin can improve the thixotropic performance of the system; the large-particle-size powders have a small specific surface area, which can significantly increase the filling amount of the powders, and the large-particle-size powders have a lower interfacial thermal resistance. The two act synergistically to increase the thermal conductivity coefficient and achieve high thermal conductivity effects.

[0030] Through the grading of insulating powders with different shapes and particle sizes, and the selection of appropriate resins and additives, the present invention can further improve the storage stability of the system and the easy-to-grind performance of the slurry after curing.

[0031] After being cured under appropriate curing conditions, the insulating plugging hole slurry of the present invention has an ultra-low thermal expansion coefficient, can match the ceramic substrate, and has a high glass transition temperature. In addition, due to the use of graded powders with specific shapes and particle sizes, the filling amount can be significantly increased, the sagging phenomenon of the slurry during the baking process can be improved, and the high-selectivity plugging hole conditions can be met. Description of the Drawings

[0032] Figure 1 It is a schematic flow chart of the preparation method of the present invention. Detailed Embodiments

[0033] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Such as Figure 1As shown in the figure, the easy-to-grind and highly thermally conductive insulating plugging paste of the present invention is prepared by the following steps:

[0035] 1) Weigh resin, curing agent, and insulating and thermally conductive powder with a particle size less than or equal to 15 microns in proportion, and mix them evenly through a high-speed mixer to obtain a preliminarily dispersed base material;

[0036] 2) Roll and grind the preliminarily dispersed base material using a three-roll mill, control the fineness to be less than 15 microns, and further improve the dispersion performance of the powder in the resin to obtain a thermally conductive base material;

[0037] 3) Add additives and insulating and thermally conductive powder with a particle size greater than 15 microns to the thermally conductive base material in sequence, and stir under vacuum for 0.5 h in a planetary stirring device to form the final thermally conductive paste.

[0038] Among them, the weight percentages of resin, curing agent, insulating and thermally conductive powder, and additives are 80 - 93 wt% of insulating and thermally conductive powder, 6 - 15 wt% of resin, 0.2 - 2 wt% of curing agent, and 0.8 - 3 wt% of additives.

[0039] Among them, the weight percentages of the insulating and thermally conductive powder include, but are not limited to, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%; the weight percentages of the resin include, but are not limited to, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%; the weight percentages of the curing agent include, but are not limited to, 0.3%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%; the weight percentages of the additives include, but are not limited to, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%.

[0040] The insulating and thermally conductive powder therein includes insulating and thermally conductive powder with an average particle size of 0.5 - 1 μm and insulating and thermally conductive powder with an average particle size of 10 - 15 microns, and the maximum particle size of the insulating powder is less than or equal to 40 μm. During the preparation process, the insulating and thermally conductive powder is screened according to the particle size, and insulating and thermally conductive powder with different particle sizes is added in different steps. The small-particle-size powder can prevent the paste from sagging during the baking process, thereby improving the easy-to-grind performance, and the large-particle-size powder can significantly increase the filler addition amount, thereby increasing the thermal conductivity.

[0041] The insulating and heat-conducting powder is at least two of boron nitride, aluminum oxide, and aluminum nitride; the shape of the insulating and heat-conducting powder is at least two combinations of flake, quasi-spherical, spherical, and angular shapes; in a preferred solution, the insulating and heat-conducting powder is a mixed powder of aluminum oxide and aluminum nitride or a mixed powder of aluminum oxide and boron nitride. Due to their low density, aluminum nitride and boron nitride can prevent the slurry from sagging, meeting the conditions of high-selectivity plugging holes, and enabling the cured slurry to have easy-to-grind characteristics. In a more preferred solution, in the mixed powder of aluminum oxide and boron nitride, the shape of the aluminum oxide powder is spherical, quasi-spherical, or angular, and the aluminum oxide powder is a powder modified for the resin system. The modified aluminum oxide powder can improve the compatibility with the resin, significantly reduce the viscosity of the system, increase the filler addition amount, and thus improve the thermal conductivity of the product. The shape of the boron nitride powder is flake-shaped, and the mass ratio of the aluminum oxide powder to the boron nitride powder is 80:1 to 10:1. Spherical / quasi-spherical and angular powders are filled into the voids of the flake powder to form a more compact packing and improve the thermal conductivity.

[0042] Specifically, the modified aluminum oxide powder is mainly modified for the epoxy system. The siloxane bond in the silane coupling agent reacts with the hydroxyl groups on the surface of the aluminum oxide powder to form chemical bonds. Through the force of the chemical bonds, organic molecules are tightly coated on the surface of the powder, making the surface of the powder organic and increasing the compatibility with the organic system. A specific modification method is, for example, chemical coupling modification. Using dipropylene glycol methyl ether as a solvent, the amount of aluminum oxide powder: silane coupling agent = 1000:1.4, stirring for 2 - 5 h, and baking at 130 °C for 1.5 - 3 h to obtain the modified powder. Among them, the silane coupling agent can be at least any one of vinyltris-(β-methoxyethoxysilane), γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and β-(3,4-epoxyhexyl)ethyltrimethoxysilane.

[0043] The resin is a liquid epoxy resin without organic solvents, including one or several combinations of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic epoxy resin, silicone-modified epoxy resin, and special multi-functional group epoxy resins, etc., but not limited thereto. As the polymer matrix resin of the insulating and heat-conducting slurry, the liquid epoxy resin has excellent physical properties, electrical insulation properties, and bonding properties. In a preferred solution, the liquid epoxy resin is one or several combinations of liquid bisphenol A epoxy resin, bisphenol F epoxy resin, and special multi-functional group epoxy resins. This resin has low viscosity and excellent chemical resistance, high temperature resistance, high cross-linking density, and other characteristics.

[0044] The curing agent is at least one of amino resin types, imidazole types, organic acid anhydride types, and dicyandiamide types. The curing agent and the main resin have a long storage period and have good physical and mechanical properties after curing at an appropriate baking temperature.

[0045] The additives mentioned above include wetting and dispersing agents, diluents, etc.; the wetting and dispersing agent is one or a combination of two of modified polysiloxane or polyurethane compounds; the diluent is an epoxy active diluent which is one or a combination of several of monofunctional glycidyl ether or polyfunctional glycidyl ether; the wetting and dispersing agent can disperse each component evenly, and the epoxy diluent contains active epoxy functional groups, participates in the reaction, and is used to adjust the viscosity, while improving the storage stability of the thermal conductive paste. According to the types of additives, the additives can improve the excellent stability of the insulating and thermal conductive paste dispersion system, and improve the stability.

[0046] The present invention will be further explained and illustrated by more specific embodiments below, but it does not constitute any limitation.

[0047] The modified alumina powder used in the embodiments was prepared by the following method:

[0048] Using dipropylene glycol methyl ether as the solvent, the amount of alumina powder: silane coupling agent (γ-mercaptopropyltrimethoxysilane) = 1000:1.4, stirring for 3 h, baking at 130 °C for 2 h, and the modified powder is obtained.

[0049] Example 1

[0050] This example provides an insulating and thermal conductive paste, and the insulating and thermal conductive paste includes the following mass percentages: liquid bisphenol A epoxy resin 3%, liquid bisphenol F epoxy resin 5%, curing agent (Ajinomoto PN-40, imidazole type) 0.6%, modified spherical alumina 79.5% (D50 = 14 μm), modified flaky alumina (D50 ≤ 7 μm) 10%, flaky boron nitride (average particle size ≤ 1 μm) 2%, p-tert-butylphenyl glycidyl ether 1.9%.

[0051] Its preparation method includes the following steps:

[0052] 1. Weigh the bisphenol A epoxy resin, bisphenol F epoxy resin, imidazole type curing agent, modified spherical alumina with a particle size not exceeding 15 μm, modified flaky alumina, and flaky boron nitride according to the contents in the above formula, mix them evenly, and then roll and grind on a three-roll mill. By controlling the gap between the rollers, roll and grind three times until the fineness is less than 15 microns, and the base material is obtained.

[0053] 2. While stirring, sequentially add p-tert-butylphenyl glycidyl ether and large particle size thermal conductive powder with a particle size exceeding 15 μm to the base material for high-speed stirring, and transfer the stirred paste to a vacuum mixer for vacuum stirring for 2 h;

[0054] 3. Set the defoaming program on the planetary and rotary defoaming machine for the paste after vacuum stirring to perform vacuum defoaming, and the thermal conductive paste is obtained.

[0055] Comparative Example 1

[0056] This comparative example provides an insulating and thermally conductive paste. The insulating and thermally conductive paste includes the following mass percentages: liquid bisphenol A epoxy resin 3%, liquid bisphenol F epoxy resin 5%, curing agent (Ajinomoto PN-40, imidazole type) 0.6%, modified spherical alumina (maximum particle size ≤ 15 μm) 79.5%, modified flaky alumina (D50 ≤ 7 μm) 10%, flaky boron nitride (average particle size ≤ 1 μm) 2%, p-tert-butylphenyl glycidyl ether 1.9%.

[0057] Its preparation method includes the following steps:

[0058] 1. Weigh liquid bisphenol A epoxy resin, liquid bisphenol F epoxy resin, curing agent, all modified spherical alumina, modified flaky alumina, flaky boron nitride, and p-tert-butylphenyl glycidyl ether according to the above formula, conduct preliminary mixing, and then perform roll grinding on a three-roll mill. By controlling the gap between the rolls, grind three times until the fineness is less than 15 μm to obtain a preliminary paste;

[0059] 2. Transfer the paste to a planetary mixer and conduct vacuum stirring for 2 h;

[0060] 3. Set a defoaming program for the stirred paste in a planetary and rotary defoaming machine to conduct vacuum defoaming to obtain the thermally conductive paste.

[0061] Comparative Example 2

[0062] This example provides an insulating and thermally conductive paste. The insulating and thermally conductive paste includes the following mass percentages: liquid phenolic epoxy resin (Dow) 10%, curing agent (Ajinomoto PN-40, imidazole type) 0.8%, modified spherical alumina (D100 = 15 μm) 84%, flaky boron nitride (D50 = 3 μm) 4.2%, butanediol diglycidyl ether 1%.

[0063] 1. Weigh liquid phenolic epoxy resin, imidazole type curing agent, and flaky boron nitride according to the content in the above formula, mix them evenly, and then perform roll grinding on a three-roll mill. By controlling the gap between the rolls, grind three times until the fineness is less than 15 μm to obtain the base material;

[0064] 2. While stirring, sequentially add butanediol diglycidyl ether and modified spherical thermal conductive powder to the base material and conduct high-speed stirring. Transfer the stirred paste to a vacuum mixer and conduct vacuum stirring for 2 h;

[0065] 3. Set a defoaming program for the paste after vacuum stirring in a planetary and rotary defoaming machine to conduct vacuum defoaming to obtain the thermally conductive paste.

[0066] Example 2

[0067] This embodiment provides an insulating and heat-conducting paste, and the insulating and heat-conducting paste comprises the following mass percentages: liquid phenolic epoxy resin (Dow) 10%, curing agent (Ajinomoto PN-40, imidazole type) 0.8%, modified spherical alumina (D50 = 13 μm) 84%, flaky boron nitride (D50 = 3 μm) 4.2%, and butanediol diglycidyl ether 1%.

[0068] 1. Weigh the liquid phenolic epoxy resin, imidazole-type curing agent, and flaky boron nitride according to the contents in the above formula, mix them evenly, and then perform roll grinding on a three-roll mill. Control the gap between the rollers and perform roll grinding three times until the fineness is less than 15 microns to obtain the base material;

[0069] 2. While stirring, sequentially add butanediol diglycidyl ether and modified spherical heat-conducting powder to the base material and carry out high-speed stirring. Transfer the stirred paste to a vacuum mixer and perform vacuum stirring for 2 h;

[0070] 3. Set a defoaming program on a planetary and rotary defoaming machine for the paste after vacuum stirring to perform vacuum defoaming to obtain the heat-conducting paste.

[0071] Example 3

[0072] This embodiment provides an insulating and heat-conducting paste, and the insulating and heat-conducting paste comprises the following mass percentages: bisphenol A epoxy resin 6%, special two-functional epoxy resin 3%, curing agent (Ajinomoto PN-40, imidazole type) 0.6%, modified spherical alumina (D50 = 10 μm) 85.3%, flaky boron nitride (D50 = 3 μm) 4.1%, and ethylene glycol diglycidyl ether (Nan Ya) 1%.

[0073] Its preparation method comprises the following steps:

[0074] 1. Weigh the bisphenol A epoxy resin, special two-functional epoxy resin, imidazole-type curing agent, and flaky boron nitride according to the contents in the above formula, mix them evenly, and then perform roll grinding on a three-roll mill. Control the gap between the rollers and perform roll grinding three times until the fineness is less than 15 microns to obtain the base material;

[0075] 2. While stirring, sequentially add p-tert-butylphenyl glycidyl ether and large-particle-size modified spherical alumina heat-conducting powder to the base material and carry out high-speed stirring. Transfer the stirred paste to a vacuum mixer and perform vacuum stirring for 2 h;

[0076] 3. Set a defoaming program on a planetary and rotary defoaming machine for the paste after vacuum stirring to perform vacuum defoaming to obtain the heat-conducting paste.

[0077] Example 4

[0078] This embodiment provides an insulating and thermally conductive paste, and the insulating and thermally conductive paste includes the following mass percentages: 10% of organosilicon-modified epoxy resin, 0.1% of curing agent (Ajinomoto PN-40, imidazole type), 0.6% of isocyanate, 78.3% of modified angular alumina (D50 = 14 microns), 8% of flaky boron nitride (D50 = 3 microns), and 3% of butanediol diglycidyl ether.

[0079] 1. Weigh the organosilicon-modified epoxy resin, imidazole-type curing agent, and flaky boron nitride according to the contents in the above formula, mix them evenly, and then perform roll grinding on a three-roll mill. Control the gap between the rollers and grind three times, with the fineness less than 15 microns to obtain the base material.

[0080] 2. While stirring, sequentially add butanediol diglycidyl ether and the large-particle-size thermally conductive powder of modified angular alumina (D50 = 14 microns) to the base material for high-speed stirring, and transfer the stirred paste to a vacuum mixer for vacuum stirring for 2 h.

[0081] 3. Set the defoaming program on the planetary and rotary defoaming machine for the paste after vacuum stirring to perform vacuum defoaming to obtain the thermally conductive paste.

[0082] Example 5

[0083] This embodiment provides an insulating and thermally conductive paste, and the insulating and thermally conductive paste includes the following mass percentages: 6% of bisphenol F-type epoxy resin, 4% of amino-difunctional epoxy resin, 0.6% of curing agent (Ajinomoto PN-40, imidazole type), 63.4% of modified angular alumina (D50 = 14 microns), 25% of flaky boron nitride (D50 = 3 microns), and 1% of polypropylene glycol diglycidyl ether.

[0084] 1. Weigh the bisphenol F-type epoxy resin, amino-difunctional epoxy resin, imidazole-type curing agent, and flaky boron nitride (D50 = 3 microns) according to the contents in the above formula, mix them evenly, and then perform roll grinding on a three-roll mill. Control the gap between the rollers and grind three times, with the fineness less than 15 microns to obtain the base material.

[0085] 2. While stirring, sequentially add polypropylene glycol diglycidyl ether and the large-particle-size thermally conductive powder of modified angular alumina (D50 = 14 microns) to the base material for high-speed stirring, and transfer the stirred paste to a vacuum mixer for vacuum stirring for 2 h.

[0086] 3. Set the defoaming program on the planetary and rotary defoaming machine for the paste after vacuum stirring to perform vacuum defoaming to obtain the thermally conductive paste.

[0087] Example 6

[0088] This embodiment provides an insulating and heat-conducting paste, and the insulating and heat-conducting paste includes the following mass percentages: amino-phenol-based trifunctional epoxy resin 6%, curing agent (Ajinomoto PN-40, imidazole type) 0.7%, modified spherical alumina (D50 = 14 μm) 68.3%, modified angular alumina (D50 = 14 μm) 17%, flaky aluminum nitride (D50 = 3 μm) 5%, and bisphenol A epoxy resin 3%.

[0089] 1. Weigh the amino-phenol-based trifunctional epoxy resin, imidazole-type curing agent, and flaky aluminum nitride according to the contents in the above formula, mix them evenly, and then perform roll grinding on a three-roll mill. Control the gap between the rollers and grind three times. When the fineness is less than 15 μm, the base material is obtained;

[0090] 2. While stirring, sequentially add the bisphenol A epoxy resin, spherical alumina, and modified angular alumina to the base material and perform high-speed stirring. Transfer the stirred paste to a vacuum mixer and perform vacuum stirring for 2 h;

[0091] 3. Set a defoaming program for the paste after vacuum stirring on a planetary and rotary defoaming machine to perform vacuum defoaming, and thus the heat-conducting paste is obtained.

[0092] Perform plugging treatment on the insulating and heat-conducting pastes of Examples 1-6 and Comparative Examples 1-2. The plugging treatment method is to use a vacuum screen printing process to plug the insulating and heat-conducting paste into the holes on the PCB board.

[0093] Bake the PCB board after plugging under the baking conditions of 110°C * 0.5 h + 130°C * 1 h + 150°C * 0.5 h. After baking and curing, perform a performance verification experiment. The thermal expansion rate is the data measured at 40 - 300°C. See Table 1 for details.

[0094] Table 1 Performance test data table of insulating plugging paste

[0095]

[0096]

[0097] It can be seen from Table 1 that the technical solution provided by the present invention adopts the compounding of powders with different particle sizes and types, which can ensure an appropriate viscosity for the printing process, reduce the interfacial thermal resistance, and thus improve the thermal conductivity; and the technical solution provided by the present invention can solve the sagging phenomenon during the vertical baking process of the paste, greatly improving the easy-grinding performance; at the same time, by adjusting the formula components, the stability during storage can be improved, and the service time of the paste can be extended.

[0098] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. An easily abradable high thermal conductivity insulating plugging paste, characterized in that, It comprises components with the following weight percentages: 80 - 93 wt% insulating and heat-conducting powder; 6 - 15 wt% resin; 0.2 - 2 wt% curing agent; 0.8 - 3 wt% additives; The preparation method of the easily grindable high heat-conducting insulating plugging paste comprises the following steps: 1) Mix a certain proportion of resin, curing agent, and insulating and heat-conducting powder with a particle size not exceeding 15 μm evenly through a high-speed mixer to obtain a preliminary base material; 2) Grind the preliminarily dispersed base material in step 1) using a three-roll mill to obtain a heat-conducting base material; 3) Add additives and insulating and heat-conducting powder with a particle size greater than 15 μm to the heat-conducting base material in sequence, and stir evenly in a planetary stirring device to form the final easily grindable high heat-conducting insulating plugging paste.

2. The easily abradable high thermal conductivity insulating plugging paste according to claim 1, characterized in that, The insulating and heat-conducting powder selects at least any two of boron nitride, aluminum oxide, and aluminum nitride.

3. The easily abradable high thermal conductivity insulating plugging paste according to claim 2, characterized in that, The insulating and heat-conducting powder is aluminum oxide and aluminum nitride, or aluminum oxide and boron nitride.

4. The easily abradable high thermal conductivity insulating plugging paste according to any one of claims 1 to 3, characterized in that, The shape of the insulating and heat-conducting powder is at least any two combinations of flake, quasi-spherical, spherical, or angular.

5. The easily abradable high thermal conductivity insulating plugging paste according to claim 4, characterized in that, The insulating and heat-conducting powder is spherical, quasi-spherical, or angular aluminum oxide powder and flaky boron nitride powder.

6. The easily abradable high thermal conductivity insulating plugging paste according to claim 5, characterized in that, The aluminum oxide powder is aluminum oxide powder modified for the resin system, and the mass ratio of the aluminum oxide powder to the boron nitride powder is 80:1 - 10:

1.

7. The easily abradable high thermal conductivity insulating plugging paste according to claim 4, characterized in that, The insulating and heat-conducting powder includes small-particle insulating and heat-conducting powder with an average particle size of 0.5 - 1 μm and large-particle insulating and heat-conducting powder with an average particle size of 10 - 15 μm, and the maximum particle size of the insulating and heat-conducting powder does not exceed 40 μm.

8. The easily abradable high thermal conductivity insulating plugging paste according to claim 7, characterized in that, The mass ratio of the small-particle insulating and heat-conducting powder to the large-particle insulating and heat-conducting powder is 5:1 - 50:

1.

9. The easily abradable high thermal conductivity insulating plugging paste according to claim 1, characterized in that, The resin is a liquid epoxy resin without organic solvents.

10. The easily abradable high thermal conductivity insulating plugging paste according to claim 9, characterized in that, The resin is selected from at least any one of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic epoxy resin, organosilicon-modified epoxy resin, and special multi-functional epoxy resin.

11. The easily abradable high thermal conductivity insulating plugging paste according to claim 10, characterized in that, The resin is one or a combination of liquid bisphenol A epoxy resin, bisphenol F epoxy resin, or special multi-functional epoxy resin.

12. The easily abradable high thermal conductivity insulating plugging paste according to claim 1, characterized in that, The curing agent is selected from at least any one of amino resin types, imidazole types, organic acid anhydride types, and dicyandiamide types.

13. The easily abradable high thermal conductivity insulating plugging paste according to claim 12, characterized in that, The curing agent is imidazole types and dicyandiamide types.

14. The easily abradable high thermal conductivity insulating plugging paste according to claim 1, characterized in that, The additives include a wetting and dispersing agent and a diluent.

15. The easy-to-abrade high thermal conductivity insulating plugging paste according to claim 14, wherein The wetting and dispersing agent is selected from one or a combination of modified polysiloxane or polyurethane compounds; the diluent is an epoxy active diluent.

16. The easy-to-abrade high thermal conductivity insulating plugging paste according to claim 15, wherein The diluent is selected from one or a combination of monofunctional glycidyl ether or polyfunctional glycidyl ether.

17. The easy-to-abrade high thermal conductivity insulating plugging paste according to claim 1, wherein In step 2), the rotation speed of the grinding is 200 r / min - 300 r / min, and it is ground until the fineness is below 15 microns.

18. The easy-to-abrade high thermal conductivity insulating plugging paste according to claim 17, wherein In step 3), the rotation speed of the stirring is 1500 r / min - 2000 r / min, and the duration is 2 - 5 hours.

19. Application of the easy-to-abrade high thermal conductivity insulating plugging paste according to any one of claims 1 to 8 in plugging holes on a ceramic substrate, 5G high-frequency or high-power board.

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