Matt glue for 3D printing and preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses matte glue for 3D printing and a preparation method and application thereof.The matte glue is prepared from, by weight, 100 parts of modified epoxy resin, 15-23 parts of first filler, 2-5 parts of second filler, 0.2-1.5 parts of curing agent, 0.5-2 parts of dispersing aid, 0.2-1 part of rheological aid and 3-10 parts of black color paste, the first filler is matt powder with a hollow structure, and the second filler is thermoplastic resin; the preparation method comprises the step of premixing the dispersed modified epoxy resin and the first filler. The viscosity of the matte glue is 200-400 mpa.s, the leveling effect can be achieved within 12 s, the 24-hour glue outlet flow fluctuation is within 3%, a cured product can optimally achieve the extinction effect (60-degree measurement angle) that the glossiness is lower than 10 GU, and meanwhile, the situation that siphon is generated on the upper surface of a chip when the matte glue is printed on a substrate is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a matte glue for 3D printing, a preparation method thereof, and an application thereof. Background Art

[0002] Compared with the wire bonding method of connecting a chip with the front side facing up to a circuit board through a gold wire, flip chip bonding uses the chip with the front side facing down, and directly connects components to a substrate, a carrier, or a circuit board through the downward bumps of the chip. Due to its way of re-layoutting the chip design and forming long gold balls (tin balls), flip chip packaging reduces the pin risk, realizes high-density interconnection, saves area and has the advantage of low cost, and the reliability is also greatly improved. As an important encapsulation adhesive in flip chip packaging, the underfill has high electrical and thermal properties. The underfill can disperse the concentrated stress on the bumps into the plastic encapsulation material and the underfill of the chip, and can prevent solder creep, increase the strength and stiffness of the flip chip connection, improve the mechanical vibration and shock tolerance of the chip, reduce the influence of the environment on the chip, and can significantly improve the thermal fatigue resistance of the chip bumps of the chip. Without the underfill, thermal fatigue would be the main reliability problem of flip chips.

[0003] In the current Mini / Micro LED industry, due to the decreasing size of the chip and the spacing between LEDs (the current spacing of Mini LEDs is 0.1 - 1.5 mm, and the spacing of Micro LEDs is less than 0.1 mm), traditional methods such as screen printing can no longer meet the commercial use of the underfill. Applying the 3D direct writing printing process to apply the glue can just solve this pain point and is applicable to the micron-level spacing of MIP Mini LEDs (chip size 460*460 μm). In order to improve color consistency and resolution, it is necessary to reduce the light-emitting area of the chip, lower the glossiness, increase the black ratio, and the panel is encapsulated with a high transmittance material (greater than 70%). For example, in order to match the application scenario of the above MIP Mini LED P 0.70404 (300 μm spacing), the underfill needs better fluidity and is constructed with a direct writing printing needle with a smaller inner diameter (printing needle inner diameter ≤ 100 μm). Although the current underfill materials on the market can solve failure problems such as cracks, corrosion, substrate delamination, voids, overheating aging, and scratches, there are problems such as the underfill siphoning onto the chip surface, unstable glue output of the printing needle, and even needle clogging during the printing process of micro-spacing. And in order to meet the requirements of micro-spacing printing and low glossiness scenarios, the underfill materials often adopt a low solid content method to reduce the viscosity, which will have a large difference in the coefficient of thermal expansion from the upper and lower substrates, resulting in chip failure in reliability tests.

[0004] The problems existing in the prior art are summarized as follows:

[0005] (1) To improve the color consistency during LED display, in the prior art, underfill adhesives that present a matte appearance after curing are mostly selected. In the prior art, matte powder with a D50 particle size usually in the range of 10 μm - 25 μm is mostly used to enhance its matte effect, and the usage ratio is above 18%. The particle size of the black material is above 1 μm. However, due to the relatively large particle sizes of both the matte powder and the black material, the phenomenon of agglomeration and needle clogging is serious. When the inner diameter of the needle head ≤ 100 μm, the glue flow rate will decrease by more than 15% within 24 hours, or even the needle will be clogged and no glue will be discharged (the larger the particle size of the matte powder, the better the matte effect and the lower the gloss, but the easier it is to clog the needle. Conventional matte powder with a particle size of 2 - 5 μm cannot meet the matte requirements). This will result in poor thickness uniformity of the underfill glue coating when using the precision dispensing process of direct writing printing, affecting the color consistency of its products and making mass production infeasible;

[0006] (2) To achieve a gloss less than 15 GU (measuring angle 60°) after curing, the proportion of matte powder in the materials on the market is 18% - 40%. At this proportion, the larger the proportion of matte powder, the greater the thixotropy, and the viscosity is usually above 2000 mPa·s. Without adding a large amount of diluent, the 12s leveling requirement cannot be met. However, adding a large amount of diluent will reduce the overall solid content of the glue, the curing shrinkage rate will be relatively large, and the flatness after curing will be poor, thus affecting the aging performance of the product, and thus it is impossible to balance the fluidity and aging performance of the product;

[0007] (3) The existing underfill adhesives have too good fluidity (viscosity is 100 - 600 mPa·s), and it is easy to have the situation that the underfill glue siphons to the surface of the chip, or the solvent overflows seriously during the curing process, and the black filler is unevenly dispersed, easily forming color difference problems, affecting the product yield;

[0008] (4) The existing underfill adhesive materials need to be stored at -20 °C. During storage, the fillers are prone to sedimentation and agglomeration. After thawing, they usually need to be remixed evenly before they can be used on the machine, and the usage process is relatively cumbersome; and they need to be used up within 24 hours after returning to room temperature, and the usage cycle is short. Summary of the Invention

[0009] In view of this, the present invention provides a matte glue applicable to the precision dispensing process of 3D printing, its preparation method and application, which solve the technical problems that in the prior art, when the matte glue meets the requirement of relatively low gloss (gloss less than 15 GU at a measuring angle of 60°), the material is prone to agglomeration and needle clogging, cannot level within a short time after printing, is easy to siphon to the surface of the chip, and has poor aging performance and stability.

[0010] In a first aspect, the present invention provides a matte glue for 3D printing, which comprises, by weight: 100 parts of modified epoxy resin, 15-23 parts of a first filler, 2-5 parts of a second filler, 0.2-1.5 parts of a curing agent, 0.5-2 parts of a dispersion aid, 0.2-1 part of a rheology aid, and 3-10 parts of a black color paste. The first filler is a matte powder with a hollow structure, and the second filler is a thermoplastic resin. The preparation method of the matte glue includes: first premixing the dispersed modified epoxy resin and the first filler, and then performing subsequent treatment.

[0011] Further, the modified epoxy resin is selected from at least one of glycidylamine type, glycidyl ester type, and mixed epoxy resin. The epoxy value of the modified epoxy resin is between 0.21 and 0.95, and the viscosity is between 400 and 3000 mPa·s. Preferably, the modified epoxy resin is selected from at least one of glycidylamine type, glycidyl ester type, and mixed epoxy resin containing hydroxyl groups. More preferably, the modified epoxy resin is selected from glycidylamine type epoxy resin containing hydroxyl groups or dimer acid modified epoxy resin.

[0012] Further, the first filler is a matte powder with a hollow structure, the particle size D90 ≤ 5 μm, and is selected from at least one of hollow-structured silica, talc, aluminum stearate, and calcium stearate. Preferably, the first filler is selected from at least one of hollow-structured silica, talc, aluminum stearate, and calcium stearate containing hydroxyl and amino groups. More preferably, the first filler is selected from ultrafine hollow-structured silica with an average particle size of 2-4 μm.

[0013] In the present invention, the dispersed modified epoxy resin and the first filler with a hollow structure are first mixed evenly in proportion. Among them, resin dispersion first can effectively improve the agglomeration and sedimentation problems of the matte powder in the glue system, can effectively reduce the viscosity of the overall matte glue system, and can pass through a 15 μm filter screen very smoothly without a three-roll and other auxiliary dispersion equipment, which can effectively improve the dispersibility of the material and reduce the viscosity. The dispersed modified epoxy resin enters the interior of the hollow matte powder to "occupy a position". The modified epoxy resin is preferably modified hydantoin epoxy resin. The hydroxyl groups of the modified hydantoin epoxy resin are used to bond with the hydroxyl and amino groups on the matte powder in advance, and each matte powder is bonded to the resin in an independent state, reducing the formation of hydrogen bonds between the hydroxyl groups of other matte powders, and preventing thixotropy and viscosity increase.

[0014] Further, the second filler is a low-molecular-weight thermoplastic resin with a molecular weight below 22000, and is selected from at least one of PMMA microspheres, silicone microspheres, acrylic microspheres, and polyurethane microspheres.

[0015] Further, the curing agent is selected from at least one of cationic latent curing agents, melamine or its derivatives, microcapsules, and polyamine salts; preferably, the curing agent is selected from cationic latent curing agents without metal elements.

[0016] Further, the dispersion aid is selected from at least one of polyether-modified phosphates, urea-formaldehyde resins, and phosphate-modified acrylic acids; preferably, the dispersion aid is selected from polyether phosphate-modified dispersants, mainly high-molecular block copolymers containing acidic groups.

[0017] Further, the premixing step includes stirring at a speed of 1500 - 2000 rpm for at least 5 minutes or more, and repeating at least 2 times or more.

[0018] Further, the method for preparing the matte glue further includes: mixing the material obtained after premixing with a rheology aid, and then performing subsequent treatment.

[0019] Further, the rheology aid is selected from at least one of polyether-modified silicones, carboxylic acid amides, fluorocarbon-modified acrylic acids, and polyesters; preferably, the rheology aid is selected from at least one of polyether-modified silicones with amide structures, carboxylic acid amides, fluorocarbon-modified acrylic acids, and polyesters; more preferably, the rheology agent is preferably polyhydroxycarboxylic acid amides. The mixture after adding the rheology aid presents a flowable paste, but does not affect the fluidity of the low-viscosity material itself in a low-viscosity system. By using the amide structure of the rheology aid to combine with part of the hydroxyl groups on the matte powder and the hydantoin resin, the three act synergistically, greatly improving the anti-settling performance of the matte powder and effectively controlling the flow of the material, avoiding the siphon of the matte glue climbing onto the chip surface, and improving the use performance of the product.

[0020] Further, the black color paste is selected from at least one of nano color pastes, epoxy color pastes, and polyurethane color pastes.

[0021] In a second aspect, the present invention provides a method for preparing a matte glue for 3D printing, the method comprising:

[0022] Mixing and stirring the modified epoxy resin with a dispersion aid to obtain a first mixture;

[0023] Mixing and stirring the first mixture with a first filler to obtain a second mixture;

[0024] Mixing and stirring the second mixture with a rheology aid to obtain a third mixture;

[0025] Mixing and stirring the third mixture with a black color paste and a solution containing a second filler to obtain the matte glue.

[0026] Further, the solution containing the second filler is a mixture of the second filler and the wetting liquid, and the weight parts of the wetting liquid are 6-20 parts; wherein, the second filler is selected from at least one of PMMA microspheres, silicone microspheres, acrylic microspheres, and polyurethane microspheres. Due to its small specific gravity and smooth surface, the second filler will float to the upper liquid surface during the curing process. The floating process will drive the matte powder to float together, generating a synergistic effect among the components, and further reducing the surface gloss of the cured matte glue.

[0027] Further, the wetting liquid is an epoxy active diluent, selected from at least one of benzyl glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, lauryl alcohol glycidyl ether, ethylene glycol diglycidyl ether, and pentaerythritol glycidyl ether; preferably, the wetting liquid is selected from ethylene glycol diglycidyl ether.

[0028] Further, before obtaining the first mixture, the modified epoxy resin and the curing agent are first mixed and dissolved, or after obtaining the first mixture, the curing agent is added.

[0029] Further, when the first mixture is mixed with the first filler, the first mixture is added in batches; the weight parts of the first mixture added for the first time can be determined according to the ratio of the number of hydroxyl and amino groups in the matte powder in the mixture and the number of hydroxyl groups in the epoxy resin. If the resin ratio is too small, the resin will not sufficiently infiltrate the matte powder, and the particles will agglomerate together, increasing its thixotropy, and the resin inside the hollow matte powder cannot effectively enter, and the viscosity will also be too large; if the resin ratio is too large, the overall viscosity of the material will be slightly lower, and the shear force during stirring is not enough, and the agglomerated state of the matte powder cannot be fully dispersed, and the dispersion is insufficient, which may cause needle clogging during printing.

[0030] Further, the stirring speed during each mixing and stirring is 1000-2500 rpm, and the stirring time is controlled at 3 minutes or more.

[0031] Further, the mixing and stirring speed for obtaining the first mixture is 1500-2000 rpm, the stirring time is 5 minutes or more, and it is repeated 2 times or more; the mixing and stirring speed for obtaining the second mixture is 1500-2000 rpm, the stirring time is 5 minutes or more, and the wall is scraped 1 time or more, and then stirred at a speed of 1800-2000 rpm for 5 minutes or more, and repeated 2 times or more; the mixing and stirring speed for obtaining the third mixture is 1500-2000 rpm, the stirring time is 3 minutes or more, and it is repeated 2 times or more; the mixing and stirring time for mixing the third mixture with the black color paste and the solution containing the second filler is 1500-2000 rpm, the stirring time is 3 minutes or more, and it is repeated 2 times or more.

[0032] In a third aspect, the present invention provides the use of the matte glue for 3D printing as an underfill glue.

[0033] The matte glue for 3D printing, its preparation method and the underfill glue provided by the present invention have the following beneficial effects:

[0034] (1) While ensuring the matte effect, this material effectively improves the needle clogging situation. The product obtained after curing the matte glue for 3D printing has a matte effect with a glossiness lower than 15 GU (measuring angle: 60°), and when using a printing needle with an inner diameter of ≤100 μm for discharging materials within 24 hours, the flow rate decrease ratio is controlled within 10%. It can effectively improve the agglomeration and needle clogging problems of the matte glue, and enhance the uniformity of the underfill glue coating thickness and the color consistency of the product;

[0035] (2) The viscosity of this material is 200 - 400 mPa·s, and it can achieve a leveling effect within 12 seconds. Moreover, the product obtained after curing accounts for more than 90% of the total mass before curing, and the curing shrinkage rate after curing is relatively small. The product has good flatness and aging performance, and the product is qualified after aging at 85% RH / 85 °C for 1000 hours, without obvious peeling or other abnormal situations;

[0036] (3) When this material is printed onto the substrate, there will be no situation of siphoning to the upper surface of the chip, and the best product obtained after curing can achieve a matte effect with a glossiness lower than 10 GU (measuring angle: 60°);

[0037] (4) This material has good room temperature stability, and the viscosity increase value within 7 days is ≤10%, without obvious sedimentation;

[0038] (5) This material has good dispersion effect, and the preparation process is simple. There is no need for treatment methods such as three - roll ball milling. After stirring and mixing evenly step by step, it can be filtered through a 15 - μm filter screen, and the filtration is smooth without residue on the filter screen. Description of the Drawings

[0039] Figure 1 It is a physical diagram of the chip before printing;

[0040] Figure 2 The physical diagram of the matte glue siphoning to the chip surface is within the red wire frame in ;

[0041] Figure 3 It is a physical diagram of the chip being printed normally;

[0042] Figure 4 It is a thickness flat - scan diagram of the chip after printing. Detailed Embodiments

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will, in combination with the embodiments of the present invention, clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0044] In the embodiment, the modified epoxy resin is selected from at least one of glycidylamine type, glycidyl ester type, and mixed epoxy resin. The epoxy value of the modified epoxy resin is between 0.21 and 0.95, and the viscosity is between 400 and 3000 mPa·s. The modified epoxy resin is preferably: modified hydantoin epoxy resin MRHC-068, which is toughened and modified by adding aliphatic hydrocarbon to hydantoin epoxy resin, with a purity of 99%, a viscosity of 640 mPa·s, and an epoxy value of 0.67; or EPD-171 of Complex High-Tech Materials (Shanghai), which is obtained by adding epichlorohydrin and dibasic fatty acid and has a purity of up to 99.5% after purification, a viscosity of 450 mPa·s, and an epoxy value of 0.24. The structure of the MHRC-068 resin is as follows:

[0045]

[0046] The curing agent is selected from at least one of cationic latent curing agents, melamine or its derivatives, microcapsules, and polyamine salts. The curing agent is preferably a cationic latent curing agent without metal elements. For example, ICAM-8416 of Start-up Applied Materials is stable at room temperature of 25°C and only initiates a chain reaction when heated to 100°C; QDP1-4125 of Shanghai Wujing Chemical Industry, which is modified with a terminal tertiary amine group hyperbranched polymer, is liquid at room temperature, has a viscosity of 10 mPa·s, is stable at room temperature when added to the epoxy resin system, and starts crosslinking at 120°C; microcapsules with a particle size of 2 μm, which are easy to disperse, have good storage stability, and start curing at 90°C, such as Asahi Kasei HX-3921HP and HX3742.

[0047] The first filler is matte powder with a hollow structure, and the particle size D90 ≤ 5 μm, which is selected from at least one of silica with a hollow structure, talc powder, aluminum stearate, and calcium stearate. The first filler is preferably SS-178B matte powder of Tosoh Silicone Chemical Co., Ltd., which is mainly modified ultrafine silica, with an average particle size of 3.4 μm, prepared by the precipitation method, hollow inside, and the surface treated with organic matter, having good hydrophobicity.

[0048] The second filler is a low-molecular-weight thermoplastic resin with a molecular weight below 22,000, and is selected from at least one of PMMA microspheres, silicone microspheres, acrylic microspheres, and polyurethane microspheres; the second filler is preferably Arkema V825 PMMA microspheres from France, with an average particle size of 3 μm, a water absorption rate of 0.3%, and a density of 1.19 g / cm³.

[0049] The black color paste is selected from at least one of nano color paste, epoxy color paste, and polyurethane color paste; the nano color paste is preferably NA-BK7 from Dongguan Thyssen Materials Company, with a solid content of 20%, a solvent of PMA, and a black material particle size of 150 - 200 nm; or the polyurethane black color paste RGB-Black 001, a low-molecular-weight polyether diol system, with a solid content of the black substance reaching 30%; or the EP-988 epoxy special black color paste from Dongguan Thyssen Materials Company, with a solid content of 15% and a black material particle size of about 300 nm.

[0050] The wetting liquid is an epoxy active diluent, selected from at least one of benzyl glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, lauryl alcohol glycidyl ether, ethylene glycol diglycidyl ether, and pentaerythritol diglycidyl ether; the wetting liquid is preferably ethylene glycol diglycidyl ether from West Asia Reagent, with a purity of 98%, a surface tension of 45.8 dyne / cm, and a boiling point of 112 °C @ 4.5 mm Hg.

[0051] Example 1

[0052] The preparation process of the matte glue for 3D printing is as follows:

[0053] (1) Weigh 3 g of Arkema V825 3-μm PMMA microspheres and 12 g of ethylene glycol diglycidyl ether, stir at a speed of 2000 rpm for 5 min, repeat 3 times, and let stand for 30 min to obtain mixture A;

[0054] (2) Weigh 100 g of modified hydantoin epoxy resin MHRC-068 and 60.5 g of curing agent ICAM-84 into a mixing tank, stir at a speed of 2000 rpm for 5 min, repeat 5 times until the curing agent is completely dissolved to obtain mixture B;

[0055] (3) Add 1 g of dispersing aid R2011 to the above 100.5 g of mixture B, stir at a speed of 2000 rpm for 5 min, repeat 2 times, and mix evenly to obtain mixture C;

[0056] (4) Weigh 18 g of matte powder SS-178B and 72.53 g of mixture C (meeting the requirement that the mass of modified epoxy resin : the mass of hollow matte powder = 3.97:1) into a mixing tank, stir at a speed of 2000 rpm for 5 min, then use a stirring rod to scrape the matte powder on the wall of the mixing tank into the mixing tank fully, and then stir at 2000 rpm for 5 min again. Repeat this process 2 times to obtain mixture D;

[0057] (5) Add the remaining 28.97 g of mixture C to the above mixture D, stir at a speed of 2000 rpm for 5 min, and repeat 2 times to obtain mixture E;

[0058] (6) Add 0.5 g of R9007 rheological aid to the above mixture E, stir at a speed of 1500 rpm for 3 min, and repeat 2 times to obtain mixture F;

[0059] (7) Add 5 g of NA-BK7 nano carbon black color paste and 15 g of mixture A to the above mixture F, stir at a speed of 1500 rpm for 3 min, and repeat 2 times to obtain mixture G;

[0060] (8) Filter the above mixture G through a filter screen with a pore size of 15 μm, and stir at 800 rpm for 3 min to complete the defoaming of the mixed slurry, and finally obtain the black underfill material H.

[0061] Example 2

[0062] The difference from Example 1 is that the mass fraction of the first filler is 15 g, and the remaining preparation steps are the same.

[0063] Example 3

[0064] The difference from Example 1 is that the mass fraction of the first filler is 23 g, and the remaining preparation steps are the same.

[0065] Example 4

[0066] The difference from Example 1 is that the mass fraction of the second filler is 2 g, and the remaining preparation steps are the same.

[0067] Example 5

[0068] The difference from Example 1 is that the mass fraction of the second filler is 5 g, and the remaining preparation steps are the same.

[0069] Example 6

[0070] The difference from Example 1 is that the mass fraction of the curing agent is 0.2 g, and the remaining preparation steps are the same.

[0071] Example 7

[0072] The difference from Example 1 is that the mass fraction of the curing agent is 1.5 g, and the remaining preparation steps are the same.

[0073] Example 8

[0074] The difference from Example 1 is that the mass fraction of the dispersion aid is 0.5 g, and the remaining preparation steps are the same.

[0075] Example 9

[0076] The difference from Example 1 is that the mass fraction of the dispersion aid is 2 g, and the remaining preparation steps are the same.

[0077] Example 10

[0078] The difference from Example 1 is that the mass fraction of the rheology aid is 0.2 g, and the remaining preparation steps are the same.

[0079] Example 11

[0080] The difference from Example 1 is that the mass fraction of the rheology aid is 1 g, and the remaining preparation steps are the same.

[0081] Example 12

[0082] The difference from Example 1 is that the mass fraction of the black color paste is 3 g, and the remaining preparation steps are the same.

[0083] Example 13

[0084] The difference from Example 1 is that the mass fraction of the black color paste is 10 g, and the remaining preparation steps are the same.

[0085] Example 14

[0086] The difference from Example 1 is that "modified hydantoin epoxy resin MHRC-068" is replaced with "complex high-tech material EPD-171", and the remaining preparation steps are the same.

[0087] Example 15

[0088] The difference from Example 1 is that "Arkema V825 3μm PMMA microspheres" is replaced with "Regal PS02 030 3μm PS particles", and the remaining preparation steps are the same.

[0089] Example 16

[0090] The difference from Example 1 is that "curing agent ICAM-8416" is replaced with "curing agent QDPI-4125", and the remaining preparation steps are the same.

[0091] Comparative Example 1

[0092] The difference from Example 1 is that no first filler is added, and the remaining preparation steps are the same.

[0093] Comparative Example 2

[0094] The difference from Example 1 is that "ultrafine silica SS-178B" is replaced with conventional silica without a hollow structure (Yufengda YF-300 silica (particle size 3 μm)), and the remaining preparation steps are the same.

[0095] Comparative Example 3

[0096] The difference from Example 1 is that no rheology aid is added, and the remaining preparation steps are the same.

[0097] Comparative Example 4

[0098] The difference from Example 1 is that "ultrafine silica SS-178B" is replaced with conventional silica without a hollow structure, and no rheology aid is added, and the remaining preparation steps are the same.

[0099] Comparative Example 5

[0100] The difference from Example 1 is that no second filler is added, and the remaining preparation steps are the same.

[0101] Comparative Example 6

[0102] The difference from Example 1 is that all components are mixed and processed in one step, and the remaining preparation steps are the same; specifically:

[0103] Steps (2)-(7) are replaced with "Mix 100 g of modified hydantoin epoxy resin MHRC-068, 0.5 g of curing agent ICAM-8416, 1 g of dispersing aid R2011, 18 g of matte powder SS-178B, 0.5 g of R9007 rheology aid, 5 g of NA-BK7 nano-carbon black color paste, and 15 g of mixture A all together, stir thoroughly at 2000 rpm for 5 min, and repeat 10 times", and the remaining preparation steps are the same.

[0104] Comparative Example 7

[0105] The difference from Example 1 is that mixture B is first mixed with the first filler and then the dispersant is added, and the remaining preparation steps are the same; specifically:

[0106] Steps (3)-(5) are replaced with "Directly mix 71.81 g of mixture B with 18 g of matte powder SS-178B in a mixing tank, stir at 2000 rpm for 5 min, then use a stirrer to scrape the matte powder on the wall of the mixing tank into the mixing tank thoroughly, and then stir at 2000 rpm for 5 min, repeat 2 times to obtain mixture C;

[0107] Then, 1 g of dispersing aid R2011 was added to mixture C, and the mixture was stirred at 2000 rpm for 5 min. This process was repeated twice to obtain mixture D;

[0108] To the above mixture D, 28.69 g of the remaining mixture B was added, and the mixture was stirred at 2000 rpm for 5 min. This process was repeated twice to obtain mixture E.

[0109] Comparative Example 8

[0110] The difference from Example 1 is that steps (6) and (7) were combined into one step, and the remaining preparation steps were the same. Specifically:

[0111] Steps (6) and (7) were replaced with "To the above mixture E, 0.5 g of rheology aid R9007, 5 g of NA - BK7 nano - carbon black color paste, and 15 g of mixture A were added, and the mixture was stirred at 1500 rpm for 3 min. This process was repeated twice to obtain mixture G".

[0112] Comparative Example 9

[0113] The difference from Example 1 is that "modified hydantoin epoxy resin MHRC - 068" was replaced with "BFE170 epoxy resin (glycidyl ether - type epoxy resin)", and the remaining preparation steps were the same.

[0114] Test Example

[0115] For the materials obtained in the above - mentioned examples and comparative examples, the viscosity value was first measured at 25°C. The viscosity value was measured using a Brookfield Next viscometer, with a 52# rotor and a rotation speed of 250 rpm;

[0116] The amount of glue discharged in 24 h was measured. Using a precision dispensing device, a ceramic needle with an inner diameter of 100 μm, a glue - discharging air pressure of 10 psi, and a back - suction of 0.15 psi, the weight of the glue discharged in each 2 - min time period was weighed, and the glue - discharging weight was measured every 1 h;

[0117] The viscosity change after 7 days was measured. For the initial sample stored at room temperature in the dark and sealed for 7 days, the viscosity value was measured using the same measurement parameters;

[0118] The 12 - s flow - leveling distance was measured. On a 10 cm * 10 cm glass slide, a straight line was printed using a dispensing device. The amount of glue in each line was the same as that for large - format printing. The image was locked under a camera. After 12 s from printing, the flow - leveling distance of the material in the image was observed, and the outward - expansion distance of each line was measured as the 12 - s flow - leveling distance data;

[0119] Solid - content test: For the same line on the above - mentioned glass slide, the weight was measured before and after curing, and the solid content was calculated;

[0120] Apply the above bottom filling adhesive material by scraping and coating it on a glass slide to form 3 groups with a thickness of 60 μm after curing, a width of 4 cm * 4 cm. Measure a set of glossiness values at a distance of 2 cm from the edge of each group. Use the CS380 SE three-angle glossiness meter from ColorPai Company for measurement, and then calculate the average value based on the 3 groups to obtain the final glossiness value;

[0121] Age the sample cured at 120 °C for 1 h at 85% RH / 85 °C for 1000 h, and monitor the aging results;

[0122] For Examples 1 - 16, confirm the siphon result. Observe the chip sample under a super-depth-of-field microscope. There are no stains such as glue marks and siphon marks on its surface, as Figure 3 shown; siphon occurs in Comparative Examples 1, 3, 6, 8, and 9, as Figure 2 shown. Figure 1 This is a physical picture before chip printing, Figure 4 This is a thickness flat scan picture after chip printing.

[0123] Table 1

[0124]

[0125]

[0126] As can be seen from Table 1, the present invention solves the above technical problems by selecting a modified epoxy resin, a hollow matte powder, and improving the resin preparation process. The core key steps are: (1) First, fully mix the dispersed resin with the matte powder. The dispersed modified epoxy resin enters the interior of the hollow matte powder to "occupy the position", and each matte powder is bonded to the resin to present an independent state, reducing the formation of hydrogen bonds with other matte powders, so as to solve the problem of agglomeration and sedimentation of matte powder in the glue system in the traditional process; (2) Utilize the amide structure of the rheological aid to combine with the matte powder and some hydroxyl groups on the hydantoin resin. The three act synergistically to greatly improve the anti-sedimentation performance of the matte powder and can effectively control the flow of the material, avoiding the siphon of the matte glue onto the chip surface and improving the use performance of the product; (3) Add the second filler fully dispersed by the wetting liquid to further improve the overall matte effect of the product; (4) The mixing of each component and their synergistic effect solve the problem that small-size fillers in the prior art cannot achieve a high matte effect. The viscosity of the final product is 200 - 400 mPa·s, it can be smoothly filtered through 15 μm, there is no situation where it siphons onto the upper surface of the chip when printed on the substrate, the flowability can reach the leveling effect within 12 s, and the fluctuation of the glue output flow within 24 h is within 3%. The cured product can achieve a matting effect with a glossiness of 11 GU (60° measurement angle), and the cured product accounts for more than 90% of the total mass before curing.

[0127] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the present invention.

Claims

1. A matte glue for 3D printing, characterized in that, Comprising by weight parts: 100 parts of modified epoxy resin, 15 - 23 parts of a first filler, 2 - 5 parts of a second filler, 0.2 - 1.5 parts of a curing agent, 0.5 - 2 parts of a dispersion aid, 0.2 - 1 part of a rheology aid, and 3 - 10 parts of a black color paste. The first filler is a matte powder with a hollow structure, and the second filler is a thermoplastic resin. The preparation method of the matte glue comprises: premixing the dispersed modified epoxy resin and the first filler.

2. The matte glue for 3D printing according to claim 1, wherein The modified epoxy resin is selected from at least one of glycidylamine type, glycidyl ester type, or mixed epoxy resins, with an epoxy value between 0.21 - 0.95 and a viscosity between 400 - 3000 mPa·s.

3. The matte glue for 3D printing according to claim 1, characterized in that, The first filler is selected from at least one of silica with a hollow structure, talc powder, aluminum stearate, and calcium stearate, with a particle size D90 ≤ 5 μm.

4. The matte glue for 3D printing according to claim 1, wherein The second filler is a low - molecular - weight thermoplastic resin with a molecular weight below 22000, and is selected from at least one of PMMA microspheres, silicone microspheres, acrylic microspheres, and polyurethane microspheres.

5. The matte glue for 3D printing according to claim 1, characterized in that, The curing agent is selected from at least one of cationic latent curing agents, melamine or its derivatives, microcapsules, and polyamine salts; and / or, the dispersion aid is selected from at least one of polyether - modified phosphates, urea - formaldehyde resins, and phosphate - modified acrylic acids; and / or, the rheology aid is selected from at least one of polyether - modified silicones, carboxylic acid amides, fluorocarbon - modified acrylic acids, and polyesters; and / or, the black color paste is selected from at least one of nano color paste, epoxy color paste, and polyurethane color paste.

6. A preparation method of the matte glue for 3D printing according to any one of claims 1-5, characterized in that, The method comprises: Mixing and stirring the modified epoxy resin and the dispersion aid to obtain a first mixture; Mixing and stirring the first mixture and the first filler to obtain a second mixture; Mixing and stirring the second mixture and the rheology aid to obtain a third mixture; Mixing and stirring the third mixture with the black color paste and a solution containing the second filler to obtain the matte glue.

7. The preparation method of the matte glue for 3D printing according to claim 6, characterized in that, The solution containing the second filler is a mixture of the second filler and an infiltration liquid, infiltrated for more than 0.5 h, and the weight parts of the infiltration liquid are 6 - 20 parts.

8. The preparation method of the matte glue for 3D printing according to claim 7, characterized in that, The infiltration liquid is selected from at least one of benzyl glycidyl ether, 1,4 - butanediol diglycidyl ether, 1,6 - hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, lauryl alcohol glycidyl ether, ethylene glycol diglycidyl ether, and pentaerythritol diglycidyl ether.

9. The preparation method of the matte glue for 3D printing according to claim 6, characterized in that, Before obtaining the first mixture, the modified epoxy resin and the curing agent are first mixed and dissolved, or after obtaining the first mixture, the curing agent is added.

10. The preparation method of the matte glue for 3D printing according to claim 6, characterized in that, When the first mixture is mixed with the first filler, the first mixture is added in batches.

11. The preparation method of the matte glue for 3D printing according to claim 6, characterized in that, The stirring speed during each mixing and stirring is 1000 - 2500 rpm, and the stirring time is controlled at 3 min and above.

12. An application of the matte glue for 3D printing according to any one of claims 1 - 5 or the matte glue for 3D printing prepared by the preparation method according to any one of claims 6 - 11 as a bottom - filling glue.

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