Low-modulus high-thermal-conductivity acrylate-based chip mounting adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to a low-modulus high-thermal-conductivity acrylate-based chip mounting adhesive and a preparation method thereof.The low-modulus high-thermal-conductivity acrylate-based chip mounting adhesive is prepared by taking acrylate as a base material and taking modified diamond and the like as additives through mixing, the flexible polymer chain segment structure contains a large amount of hydroxyl substituent groups generated by ring-opening reaction, so that the flexible polymer chain segment structure can participate in the subsequent curing process of the acrylate mounting adhesive, and the diamond and the acrylate mounting adhesive can generate a good interface effect, so that a dispersing agent is more uniformly added into acrylate, and the purposes of adding a small amount of the dispersing agent and adding a small amount of the dispersing agent are achieved. In addition, in the curing process, the flexible macromolecular chain segment is introduced into the acrylate structure, and the modulus of the mounting adhesive can be effectively reduced by utilizing the flexibility of the flexible macromolecular chain segment.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive and its preparation method. Background Technology

[0002] Chip mounting adhesives are key materials in microelectronic packaging, used to fix semiconductor chips onto substrates or lead frames. Their performance directly affects the mechanical stability, heat dissipation efficiency, and long-term reliability of packaged devices. As semiconductor technology advances towards higher density, higher power, and miniaturization, mounting adhesives need to meet increasingly stringent comprehensive performance requirements. Acrylic adhesives are polymer materials copolymerized from acrylate monomers, widely used in chip mounting due to their distinct characteristics, including mild curing conditions, good process adaptability, high bond strength, and electrical insulation. Therefore, they can be used as a base material for chip mounting adhesives. However, acrylic adhesives have poor thermal conductivity, making it difficult to meet the high-efficiency heat dissipation requirements of high-power chips. Furthermore, their relatively high modulus makes them less effective at mitigating thermal stress. Therefore, developing acrylic adhesives with low modulus and high thermal conductivity is of great significance for their application in the field of chip mounting adhesives.

[0003] Currently, improving the thermal conductivity of acrylic adhesives is generally achieved by adding thermally conductive additives. However, the natural interface problem between inorganic thermally conductive additives and the acrylic matrix is ​​a major drawback of this approach. On the one hand, a small amount of additive cannot form a stable thermal conductivity pathway to achieve thermal conductivity modification of the acrylic adhesive. On the other hand, an excessively large amount of additive will increase the modulus of the acrylic adhesive. Based on this, the present invention provides an acrylic-based chip mounting adhesive that can solve the problems existing in the prior art. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive and its preparation method.

[0005] A first aspect of the present invention provides a low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive, comprising the following raw materials measured in parts by weight:

[0006] 26-34 parts soft monomer, 10-16 parts hard monomer, 3-6 parts internal plasticizer, 80-100 parts ethyl acetate, 0.05-0.15 parts initiator, 2-4.5 parts modified diamond, and 1-3 parts curing agent;

[0007] The modified diamond is prepared by modifying the surface of diamond with flexible molecular chain segments containing silicon-oxygen bonds.

[0008] As a preferred embodiment of the present invention, the soft monomer is at least one of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, or lauryl acrylate; the hard monomer is at least one of methyl methacrylate, styrene, acrylonitrile, or methyl acrylate; the internal plasticizer is hydroxyethyl acrylate or hydroxypropyl acrylate; the initiator is azobisisobutyronitrile or azobisisoheptanenitrile; and the curing agent is an isocyanate curing agent.

[0009] As a preferred embodiment of the present invention, the modified diamond is prepared by the following steps:

[0010] Step 1: Add diamond to an ethanol aqueous solution with a volume fraction of 60-70%, disperse evenly, and then continue to add epoxidation modifying reagent. After the addition is complete, adjust the pH to 3-4, keep it at the temperature for 3-6 hours, cool down and discharge the material, collect the solid material, wash and vacuum dry it to obtain epoxidized diamond.

[0011] Step 2: Disperse epoxide diamond in 1,4-dioxane, and add polytetrahydrofuran ether diol and catalyst to the formed homogeneous mixture. After the addition is complete, stir well, raise the temperature to 60-70℃, and keep it at this temperature for 2-4 hours. Then, continue to add silicon-containing crosslinking agent. After the addition is complete, raise the temperature further to 75-85℃ and keep it at this temperature for 12-18 hours. Then, stop heating, cool down and discharge the material, collect the solid material, and wash and vacuum dry it to obtain modified diamond.

[0012] As a preferred embodiment of the present invention, in step one, the epoxidation modifying agent is 3-glycidyl etheroxypropyltrimethoxysilane or 3-glycidyl etheroxypropyltriethoxysilane.

[0013] As a preferred embodiment of the present invention, in step two, the number-average molecular weight of the polytetrahydrofuran ether diol is 1000.

[0014] As a preferred embodiment of the present invention, in step two, the catalyst is a boron trifluoride diethyl ether complex.

[0015] As a preferred embodiment of the present invention, in step two, the silicon-containing crosslinking agent is prepared by the following method:

[0016] Decamethyldihydropentasiloxane, glycidyl methacrylate, and anhydrous ethanol were added to a reaction vessel, and nitrogen gas was introduced for protection. The mixture was then heated to 70-75°C under stirring. Platinum catalyst was then added. After the addition was complete, the mixture was kept at this temperature for 4-6 hours. The solvent was removed by vacuum distillation, and the product was collected after natural cooling. The product was then purified to obtain a silicon-containing crosslinking agent.

[0017] As a preferred embodiment of the present invention, the molar ratio of decamethyldihydropentasiloxane and glycidyl methacrylate is 1:2-2.05.

[0018] As a preferred embodiment of the present invention, the mass ratio of the epoxidized diamond, polytetrahydrofuran ether diol and the silicon-containing crosslinking agent is 1:0.3-0.6:0.2-0.4.

[0019] It should be noted that in the above technical solution, firstly, the surface of diamond is epoxidized using an epoxidation modifying agent to obtain epoxidized diamond. Then, under the action of a catalyst, the epoxy groups of the epoxidized diamond can ring-open with the hydroxyl groups in the polytetrahydrofuran ether diol structure. Using polytetrahydrofuran ether diol as a linker, a continuous ring-opening reaction is carried out with a silicon-containing crosslinking agent, thereby in-situ polymerization of flexible polymer segments with alternating siloxane segments and ether segments on the diamond surface to obtain modified diamond.

[0020] The silicon-containing crosslinking agent is prepared by using decamethyldihydropentasiloxane and glycidyl methacrylate as raw materials, controlling the molar ratio of the two, and undergoing a hydrosilylation reaction under the action of a platinum catalyst to obtain a siloxane derivative containing two equivalent epoxy substituents in its structure, namely the silicon-containing crosslinking agent.

[0021] A second aspect of the present invention provides a method for preparing a low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive, comprising the following steps:

[0022] Step 1: Weigh and prepare all raw materials according to the weight proportions. First, add the soft monomer, hard monomer, internal plasticizer and initiator to ethyl acetate, stir and mix evenly, turn on the heating, raise the temperature to 75-76℃, keep it at the temperature for 6-8 hours, then stop the heating, cool down and discharge the material to obtain the polymer.

[0023] The second step is to add the modified diamond to the polymer, stir and mix it, and then add the curing agent and stir until it is evenly mixed to obtain the chip mounting adhesive.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention modifies diamond by modifying its surface with flexible polymer segments. As an additive, the flexible polymer segments contain numerous hydroxyl substituents generated by ring-opening reactions, enabling them to participate in the subsequent curing process of the acrylate adhesive. This allows the diamond to interact well with the acrylate adhesive, resulting in a more uniform dispersion of the agent within the acrylate. Even a small amount of addition can form a complete thermally conductive pathway, significantly improving the thermal conductivity of the acrylate adhesive. Furthermore, introducing the flexible polymer segments into the acrylate structure during curing effectively reduces the modulus of the adhesive by utilizing the flexibility of the polymer segments. Detailed Implementation

[0026] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0027] Example 1

[0028] This embodiment provides a low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive, comprising the following raw materials measured in parts by weight:

[0029] 26 parts ethyl acrylate, 10 parts methyl methacrylate, 3 parts hydroxyethyl acrylate, 80 parts ethyl acetate, 0.05 parts azobisisobutyronitrile, 2 parts modified diamond, and 1 part toluene-2,4-diisocyanate;

[0030] The preparation method of the chip mounting adhesive includes the following steps:

[0031] Step 1: Weigh and prepare all raw materials according to the specified weight proportions. First, add ethyl acrylate, methyl methacrylate, hydroxyethyl acrylate and azobisisobutyronitrile to ethyl acetate, stir and mix evenly, turn on the heater, raise the temperature to 75°C, keep it at the temperature for 6 hours, then stop the heating, cool down and discharge the material to obtain the polymer.

[0032] The second step is to add the modified diamond to the polymer, stir and mix, and then add toluene-2,4-diisocyanate and stir until homogeneous to obtain the chip mounting adhesive.

[0033] The modified diamond is produced using the following steps:

[0034] Step A: Add 5g of diamond to a 60% (v / v) ethanol aqueous solution and disperse it evenly. Then add 0.8g of 3-glycidyl etheroxypropyltrimethoxysilane. After the addition is complete, adjust the pH to 4 and keep it at the temperature for 4 hours. Then cool down and discharge the material. Collect the solid material, wash it, and vacuum dry it to obtain epoxide diamond.

[0035] Step B: Add 0.5g decamethyldihydropentasiloxane, 0.4g glycidyl methacrylate and anhydrous ethanol to the reaction vessel, purge with nitrogen for protection, and then heat to 70°C under stirring. Next, add 0.001g platinum catalyst. After the addition is complete, keep warm for 6 hours, remove the solvent by vacuum distillation, and collect the product after natural cooling. After purification, obtain the silicon-containing crosslinking agent.

[0036] Step C: Disperse 1.4g of epoxide diamond in 1,4-dioxane, and add 0.6g of polytetrahydrofuran ether diol with a number average molecular weight of 1000 and 0.01g of boron trifluoride diethyl ether complex to the formed homogeneous mixture. After the addition is complete, stir well, raise the temperature to 65℃, keep it at that temperature for 3 hours, and then add 0.5g of silicon-containing crosslinking agent. After the addition is complete, raise the temperature to 80℃ and keep it at that temperature for 16 hours. Then stop heating, cool down and discharge the material, collect the solid material, and wash and vacuum dry it to obtain modified diamond.

[0037] Example 2

[0038] This embodiment provides a low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive, comprising the following raw materials measured in parts by weight:

[0039] 28 parts butyl acrylate, 12 parts methyl acrylate, 5 parts hydroxypropyl acrylate, 90 parts ethyl acetate, 0.1 parts azobisisobutyronitrile, 4 parts modified diamond, and 2 parts toluene-2,4-diisocyanate;

[0040] The preparation method of the chip mounting adhesive includes the following steps:

[0041] Step 1: Weigh and prepare all raw materials according to the specified weight proportions. First, add butyl acrylate, methyl acrylate, hydroxypropyl acrylate and azobisisobutyronitrile to ethyl acetate, stir and mix evenly, then turn on the heater and raise the temperature to 76°C. After holding at this temperature for 8 hours, stop the heating, cool down and discharge the material to obtain the polymer.

[0042] The second step is to add the modified diamond to the polymer, stir and mix, and then add toluene-2,4-diisocyanate and stir until homogeneous to obtain the chip mounting adhesive.

[0043] The preparation method of the modified diamond is the same as that in Example 1.

[0044] Example 3

[0045] This embodiment provides a low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive, comprising the following raw materials measured in parts by weight:

[0046] 34 parts ethyl acrylate, 16 parts methyl methacrylate, 6 parts hydroxyethyl acrylate, 100 parts ethyl acetate, 0.15 parts azobisisobutyronitrile, 4.5 parts modified diamond, and 3 parts toluene-2,4-diisocyanate;

[0047] The preparation method of the chip mounting adhesive includes the following steps:

[0048] Step 1: Weigh and prepare all raw materials according to the specified weight proportions. First, add ethyl acrylate, methyl methacrylate, hydroxyethyl acrylate and azobisisobutyronitrile to ethyl acetate, stir and mix evenly, then turn on the heater and raise the temperature to 76°C. After holding at this temperature for 6 hours, stop the heating, cool down and discharge the material to obtain the polymer.

[0049] The second step is to add the modified diamond to the polymer, stir and mix, and then add toluene-2,4-diisocyanate and stir until homogeneous to obtain the chip mounting adhesive.

[0050] The preparation method of the modified diamond is the same as that in Example 1.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 2 is that the modified diamond is replaced with diamond, otherwise they are the same.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 2 is that the modified diamond is removed, but otherwise they are the same.

[0055] Comparative Example 3:

[0056] The difference between this comparative example and Example 2 is that epoxide diamond is used instead of modified diamond, that is, only step A is performed;

[0057] Comparative Example 4:

[0058] Use common silanes instead of silicon-containing crosslinking agents;

[0059] Comparative Example 5:

[0060] No silicon-containing crosslinking agents added;

[0061] Test case

[0062] According to standard ISO 527-2, the modulus of the mounting adhesive in the test examples and comparative examples was tested;

[0063] The thermal conductivity of the adhesives in the examples and comparative examples was tested at room temperature according to standard ASTM D-5470.

[0064] The performance test data above are shown in Table 1.

[0065] Table 1 Performance Test Results

[0066] Modulus (MPa) Thermal conductivity (W / (m•K)) Example 1 12.5 2.8 Example 2 12.1 2.9 Example 3 12.4 2.8 Comparative Example 1 19.9 2.1 Comparative Example 2 18.8 1.0 Comparative Example 3 19.3 1.5

[0067] As can be seen from the above, the mounting adhesive prepared in the embodiments of the present invention has low modulus and high thermal conductivity, which can meet the requirements of mounting adhesive use. Replacing modified diamond with diamond has an interface problem between diamond and acrylate matrix, which makes it impossible for diamond to be evenly dispersed and form a continuous thermal conductive path, resulting in a significant reduction in the various properties of the mounting adhesive.

[0068] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive, characterized in that, Including the following raw materials measured in parts by weight: 26-34 parts soft monomer, 10-16 parts hard monomer, 3-6 parts internal plasticizer, 80-100 parts ethyl acetate, 0.05-0.15 parts initiator, 2-4.5 parts modified diamond, and 1-3 parts curing agent; The modified diamond is prepared by modifying the surface of diamond with flexible molecular chain segments containing silicon-oxygen bonds.

2. The low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive according to claim 1, characterized in that, The soft monomer is at least one of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, or lauryl acrylate; the hard monomer is at least one of methyl methacrylate, styrene, acrylonitrile, or methyl acrylate; the internal plasticizer is hydroxyethyl acrylate or hydroxypropyl acrylate; the initiator is azobisisobutyronitrile or azobisisoheptanenitrile; and the curing agent is an isocyanate curing agent.

3. The low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive according to claim 1, characterized in that, The modified diamond is produced using the following steps: Step 1: Add diamond to an ethanol aqueous solution with a volume fraction of 60-70%, disperse evenly, and then continue to add epoxidation modifying reagent. After the addition is complete, adjust the pH to 3-4, keep it at the temperature for 3-6 hours, cool down and discharge the material, collect the solid material, wash and vacuum dry it to obtain epoxidized diamond. Step 2: Disperse epoxide diamond in 1,4-dioxane, and add polytetrahydrofuran ether diol and catalyst to the formed homogeneous mixture. After the addition is complete, stir well, raise the temperature to 60-70℃, and keep it at this temperature for 2-4 hours. Then, continue to add silicon-containing crosslinking agent. After the addition is complete, raise the temperature further to 75-85℃ and keep it at this temperature for 12-18 hours. Then, stop heating, cool down and discharge the material, collect the solid material, and wash and vacuum dry it to obtain modified diamond.

4. The low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive according to claim 3, characterized in that, In step one, the epoxidation modifying agent is 3-glycidyl etheroxypropyltrimethoxysilane or 3-glycidyl etheroxypropyltriethoxysilane.

5. The low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive according to claim 3, characterized in that, In step two, the number-average molecular weight of the polytetrahydrofuran ether diol is 1000.

6. The low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive according to claim 3, characterized in that, In step two, the catalyst is a boron trifluoride diethyl ether complex.

7. The low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive according to claim 3, characterized in that, In step two, the silicon-containing crosslinking agent is prepared using the following method: Decamethyldihydropentasiloxane, glycidyl methacrylate, and anhydrous ethanol were added to a reaction vessel, and nitrogen gas was introduced for protection. The mixture was then heated to 70-75°C under stirring. Platinum catalyst was then added. After the addition was complete, the mixture was kept at this temperature for 4-6 hours. The solvent was removed by vacuum distillation, and the product was collected after natural cooling. The product was then purified to obtain a silicon-containing crosslinking agent.

8. The low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive according to claim 7, characterized in that, The molar ratio of decamethyldihydropentasiloxane and glycidyl methacrylate is 1:2-2.

05.

9. The low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive according to claim 3, characterized in that, The mass ratio of the epoxide diamond, polytetrahydrofuran ether diol and the silicon-containing crosslinking agent is 1:0.3-0.6:0.2-0.

4.

10. A method for preparing the low-modulus, high-thermal-conductivity acrylate-based chip mounting adhesive as described in claim 1, characterized in that, Includes the following steps: Step 1: Weigh and prepare all raw materials according to the weight proportions. First, add the soft monomer, hard monomer, internal plasticizer and initiator to ethyl acetate, stir and mix evenly, turn on the heating, raise the temperature to 75-76℃, keep it at the temperature for 6-8 hours, then stop the heating, cool down and discharge the material to obtain the polymer. The second step is to add the modified diamond to the polymer, stir and mix it, and then add the curing agent and stir until it is evenly mixed to obtain the chip mounting adhesive.