Low-shrinkage packaging material and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor packaging materials, and particularly discloses a low-shrinkage packaging material and a preparation method thereof. The invention relates to a low-shrinkage packaging material, which is prepared from the following raw materials: 70 to 76 ml of epoxy resin, 15 to 25 g of spiral expansion monomer and 3 to 4 g of boron trifluoride ethylamine. The preparation method comprises the following steps: weighing 15-25g of spiral expansion monomer and 70-76ml of epoxy resin, uniformly mixing, adding 3-4g of boron trifluoride ethylamine, stirring, uniformly stirring, putting into a vacuum drying oven at 50-70 DEG C, degassing until no bubble exists, pouring into a mold preheated to 110-130 DEG C, then putting into a drying oven at 145-155 DEG C, and curing for 3-5 hours. The low-shrinkage packaging material has the advantage that the defect that the packaging material is prone to volume shrinkage during curing can be overcome.

Description

Technical Field

[0001] This application relates to the technical field of semiconductor packaging materials, and more specifically, it relates to a low-shrinkage packaging material and a preparation method thereof. Background Art

[0002] With the development of high integration and high performance in the semiconductor industry, packaging materials, as key materials for electronic devices such as integrated circuits, light-emitting diodes, mini light-emitting diodes, and micro light-emitting diodes, the performance of chip-level packaging materials is crucial. Among them, the shrinkage stress generated during the curing process of packaging materials can cause problems such as chip cracking and interface debonding, seriously affecting the reliability and service life of devices.

[0003] Epoxy resin has high tensile strength and modulus, excellent adhesion performance, good chemical resistance, solvent resistance, and electrical insulation properties, so it is widely used in fields such as adhesives, coatings, semiconductor packaging materials, and insulating materials. However, epoxy resin often undergoes volume shrinkage during the curing process. After gelation, further shrinkage will lead to residual stress inside the material. Summary of the Invention

[0004] In order to improve the defect of easy volume shrinkage during the curing of packaging materials, this application provides a low-shrinkage packaging material and a preparation method thereof.

[0005] In the first aspect, a low-shrinkage packaging material provided by this application adopts the following technical solution:

[0006] A low-shrinkage packaging material includes the following raw materials: 70 - 76 ml of epoxy resin, 15 - 25 g of spirocyclic expansion monomer, and 3 - 4 g of boron trifluoride ethylamine.

[0007] Since the curing shrinkage rate of epoxy resin varies with different curing agents and curing systems, generally ranging from 2% to 7%, and during the curing process of the packaging material, the spirocyclic expansion monomer can undergo ring-opening polymerization reaction. The originally compact covalent bond connection method changes, the distance between atoms increases, the molecular conformation stretches, occupies a larger space, and the molecular structure expands to generate volume expansion, which can compensate for the shrinkage during the curing of epoxy resin.

[0008] Preferably, the spirocyclic expansion monomer includes the following raw materials: 5 - 8 g of bis(trimethylol)propane, 6 - 8.8 ml of tetraethyl orthocarbonate, 0.05 - 0.13 g of p-toluenesulfonic acid, 1 - 3 ml of diethyl carbonate, 0.01 - 0.03 g of potassium hydroxide, and 1.5 - 2.8 g of modified thermal conductive agent.

[0009] Due to the presence of multiple hydroxyl groups in bis(trimethylol)propane, it has high reactivity and can provide abundant active sites for subsequent reactions. It condenses with tetraethyl orthocarbonate under the catalysis of p-toluenesulfonic acid to form a spiro structure, endowing the ability of volume expansion during curing to compensate for the shrinkage of epoxy resin. Diethyl carbonate, as the reaction solvent, is beneficial to promoting the uniform dispersion of raw materials. Potassium hydroxide regulates the reaction process, which is conducive to the complete formation of the spiro structure. The added modified thermal conductive agent can improve the thermal conductivity of the material, timely conduct the heat generated during the curing process, reduce the shrinkage deformation caused by thermal stress, and at the same time is beneficial to improving the heat dissipation performance after encapsulation.

[0010] Preferably, the preparation method of the spiro-type expanding monomer: Weigh 5 - 8 g of bis(trimethylol)propane and 6 - 8.8 ml of tetraethyl orthocarbonate and add them into a flask, under nitrogen protection, then add 0.05 - 0.13 g of p-toluenesulfonic acid, slowly raise the temperature to 50 - 70 °C, stir and react for 0.5 - 1.5 h, then cool down to 35 - 45 °C, slowly add 1 - 3 ml of diethyl carbonate, raise the temperature to 70 - 90 °C, continue to react for 0.5 - 1.5 h, then add 0.01 - 0.03 g of potassium hydroxide, and continue to react for 1 - 3 h under the condition of 75 - 85 °C, then add 1.5 - 2.8 g of the modified thermal conductive agent, and stir and disperse for 20 - 40 min.

[0011] Initiate the ring-opening reaction of bis(trimethylol)propane and tetraethyl orthocarbonate at a lower temperature, and slowly induce the formation of the spiro structure through an acidic catalyst (p-toluenesulfonic acid) to avoid side reactions (such as excessive cross-linking or decomposition), ensure the regularity of the molecular chain, which is beneficial to improving the controllability of monomer synthesis, reducing the generation of impurities, and laying a foundation for the subsequent expansion function. After adding diethyl carbonate, raise the temperature to adjust the reaction activity and promote the extension and cross-linking of the molecular chain. Diethyl carbonate, as a reaction diluent, slows down the gas release rate, making it difficult for bubbles to quickly aggregate and cause a loose structure, which is beneficial to achieving the dynamic balance of gas release and expansion rate and avoiding the porousness of the material. Add potassium hydroxide to neutralize the acidic catalyst and terminate the gas release reaction. At the same time, stabilize the system through an alkaline environment, making it difficult for the residual acid to trigger subsequent side reactions, which is beneficial to the stability of the reaction system and is not prone to excessive expansion or uneven shrinkage.

[0012] Preferably, the modified thermal conductive agent includes the following raw materials: 1 - 3 g of modified boron nitride, 0.03 - 0.07 g of sodium hexametaphosphate, 50 - 90 ml of deionized water, 8 - 12 ml of sodium hydroxide solution, 10 - 12 ml of sodium silicate solution, 20 - 30 ml of dilute nitric acid solution.

[0013] Since sodium hexametaphosphate acts as a dispersant, it can effectively prevent the modified boron nitride from agglomerating. Through electrostatic repulsion and steric hindrance, it is evenly dispersed in the matrix to form a continuous heat conduction network, thereby improving the heat conduction efficiency. Sodium silicate, as a silica precursor, hydrolyzes to form silicate ions under alkaline conditions. Dilute nitric acid gradually reduces the pH value of the system, which is conducive to triggering the condensation of silicate ions to form a silica coating layer.

[0014] Preferably, the preparation method of the modified thermal conductive agent is as follows: Weigh 0.03 - 0.07 g of sodium hexametaphosphate and dissolve it in 50 - 90 ml of deionized water. While stirring, add 1 - 3 g of modified boron nitride, and ultrasonically disperse for 20 - 40 min. Then transfer it to a constant temperature water bath with the temperature constant at 85 - 95 °C, stir, slowly add 8 - 12 ml of sodium hydroxide solution, then slowly dropwise add 10 - 12 ml of sodium silicate solution and 20 - 30 ml of dilute nitric acid solution, stir for 3 - 7 min, then keep warm and age for 1 - 3 h, filter, wash with deionized water, and then dry at 95 - 115 °C for 22 - 26 h.

[0015] Preferably, the modified boron nitride includes the following raw materials: 0.45 - 0.49 g of 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide, 0.1 - 0.3 ml of 1 - vinylimidazole, 5 - 6 ml of absolute ethanol, 0.1 - 0.16 g of ferric nitrate nonahydrate, and 1 - 1.4 g of hexagonal boron nitride.

[0016] Since 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide is a phosphorus - containing compound, the modified boron nitride can not only have excellent thermal conductivity but also good flame - retardant properties. The iron ions in ferric nitrate nonahydrate can coordinate with nitrogen atoms to form a coordination bond network, constructing an organic - inorganic transition layer on the surface of boron nitride, so that it can not only maintain the thermal conductivity of boron nitride but also improve its compatibility.

[0017] Preferably, the preparation method of the modified boron nitride is as follows: Weigh 0.45 - 0.49 g of 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide in a flask and heat it to 120 - 160 °C, add 0.1 - 0.3 ml of 1 - vinylimidazole, heat it to 150 - 170 °C and reflux for 10 - 14 h, then cool it to 75 - 85 °C, add 1.5 - 2.5 ml of absolute ethanol, stir to obtain a premixed solution. Weigh 1 - 1.4 g of hexagonal boron nitride and disperse it in 1 - 3 ml of absolute ethanol, and stir - mix it with the premixed solution to obtain a mixed solution. Disperse 0.1 - 0.16 g of ferric nitrate nonahydrate in 1 - 2 ml of absolute ethanol and gradually add it dropwise to the mixed solution, continue to stir for 0.5 - 1.5 h, and then carry out centrifugation, washing and drying.

[0018] Second aspect, the present application provides a method for preparing a low shrinkage encapsulation material, adopting the following technical solution:

[0019] A method for preparing a low shrinkage encapsulation material, comprising the following steps:

[0020] S1: Weigh 15 - 25 g of spirocyclic expansion monomer and 70 - 76 ml of epoxy resin, mix them evenly, then add 3 - 4 g of boron trifluoride ethylamine, stir. After stirring evenly, place it in a vacuum oven at 50 - 70 °C for degassing. After degassing until there are no bubbles, pour it into a mold preheated to 110 - 130 °C, and then place it in an oven at 145 - 155 °C for curing for 3 - 5 h.

[0021] In summary, the present application has the following beneficial effects:

[0022] 1. Since the curing shrinkage rate of epoxy resin varies with different curing agents and curing systems, generally ranging from 2 - 7%, and during the curing process of the encapsulation material, the spirocyclic expansion monomer can undergo ring-opening polymerization reaction. The originally compact covalent bond connection mode changes, the distance between atoms increases, the molecular conformation stretches, occupies a larger space, and the molecular structure expands to generate volume expansion, which can compensate for the shrinkage during the curing of epoxy resin.

[0023] 2. Since bis(trimethylol)propane contains multiple hydroxyl groups and has high reaction activity, it can provide rich active sites for subsequent reactions. It condenses with tetraethyl orthocarbonate under the catalysis of p-toluenesulfonic acid to form a spiro structure, endowing the ability of volume expansion during curing to compensate for the shrinkage of epoxy resin. Diethyl carbonate as a reaction solvent is conducive to promoting the uniform dispersion of raw materials. Potassium hydroxide regulates the reaction process, which is beneficial to the complete formation of the spiro structure. The added modified thermal conductive agent can improve the thermal conductivity of the material, timely conduct the heat generated during the curing process, reduce the shrinkage deformation caused by thermal stress, and at the same time is beneficial to improving the heat dissipation performance after encapsulation.

[0024] 3. Initiate the ring-opening reaction of bis(trimethylol)propane and tetraethyl orthocarbonate at a lower temperature, slowly induce the formation of the spiro structure through an acidic catalyst (p-toluenesulfonic acid), avoid side reactions (such as over-crosslinking or decomposition), ensure the regularity of the molecular chain, which is beneficial to improving the controllability of monomer synthesis, reducing the generation of impurities, and laying a foundation for the subsequent expansion function. After adding diethyl carbonate, raise the temperature to adjust the reaction activity and promote the extension and crosslinking of the molecular chain. Diethyl carbonate as a reaction diluent slows down the gas release rate, making it difficult for bubbles to quickly aggregate and cause structural looseness, which is beneficial to achieving the dynamic balance of gas release and expansion rate, avoiding material porousization. Add potassium hydroxide to neutralize the acidic catalyst and terminate the gas release reaction. At the same time, stabilize the system through an alkaline environment, making it difficult for the residual acid to trigger subsequent side reactions, which is beneficial to the stability of the reaction system and is not prone to excessive expansion or uneven shrinkage. Detailed implementation manners

[0025] The present application will be further described in detail below in conjunction with Examples 1-10 and Comparative Examples 1-2.

[0026] Raw materials

[0027] Epoxy resin CAS: 38891-59-7; bis(trimethylol)propane CAS: 23235-61-2; tetraethyl orthocarbonate CAS: 78-09-1; p-toluenesulfonic acid CAS: 104-15-4; diethyl carbonate CAS: 105-58-8; potassium hydroxide CAS: 1310-58-3; nitrogen CAS: 7727-37-9; sodium hexametaphosphate CAS: 10124-56-8; deionized water CAS: 7732-18-5; sodium hydroxide CAS: 1310-73-2; sodium silicate; dilute nitric acid CAS: 1344-09-8; 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide CAS: 35948-25-5; 1-vinylimidazole CAS: 1072-63-5; absolute ethanol CAS: 64-17-5; iron(III) nitrate nonahydrate CAS: 7782-61-8; hexagonal boron nitride Bohuasi Nano-Technology Co., Ltd.; boron trifluoride ethylamine CAS: 75-23-0.

[0028] Example 1

[0029] A low shrinkage encapsulation material, comprising the following raw materials: 73 ml of epoxy resin, 20 g of spiro type expansion monomer, and 3.5 g of boron trifluoride ethylamine.

[0030] Specifically, the preparation method of the low shrinkage encapsulation material comprises the following steps:

[0031] S1: Weigh 0.47 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a flask, heat it to 140 °C, add 0.2 ml of 1-vinylimidazole, heat it to 160 °C and reflux for 12 h, then cool it to 80 °C, add 2 ml of absolute ethanol, stir to obtain a premixed solution. Weigh 1.2 g of hexagonal boron nitride and disperse it in 2 ml of absolute ethanol, and stir and mix it with the premixed solution to obtain a mixed solution. Disperse 0.13 g of iron(III) nitrate nonahydrate in 1.5 ml of absolute ethanol, and add it dropwise to the mixed solution, continue to stir for 1 h, then centrifuge, wash and dry to obtain modified boron nitride;

[0032] S2: Weigh 0.05 g of sodium hexametaphosphate and dissolve it in 70 ml of deionized water. While stirring, add 2 g of modified boron nitride, and perform ultrasonic dispersion for 30 min. Then transfer it to a constant temperature water bath, keep the temperature constant at 90 °C, stir, slowly add 10 ml of sodium hydroxide solution, then slowly dropwise add 11 ml of sodium silicate solution and 25 ml of dilute nitric acid solution, stir for 5 min, then keep it warm and age for 2 h, filter, wash with deionized water, and then dry at 105 °C for 24 h to obtain the modified thermal conductive agent;

[0033] S3: Weigh 6.5 g of bis(trimethylol)propane and 7.4 ml of tetraethyl orthocarbonate and add them to a flask. Under nitrogen protection, then add 0.09 g of p-toluenesulfonic acid, slowly heat up to 60 °C, stir and react for 1 h. Then cool down to 40 °C, slowly add 2 ml of diethyl carbonate, heat up to 80 °C, and continue to react for 1 h. Then add 0.02 g of potassium hydroxide and continue to react at 80 °C for 2 h. Then add 2.2 g of the modified thermal conductive agent and stir and disperse for 30 min to obtain the spirocyclic expanding monomer;

[0034] S4: Weigh 20 g of the spirocyclic expanding monomer and 73 ml of epoxy resin and mix them evenly. Then add 3.5 g of boron trifluoride ethylamine and stir. After stirring evenly, put it into a vacuum oven at 60 °C for degassing. After degassing until there are no bubbles, pour it into a mold preheated to 120 °C, and then put it into an oven at 150 °C and cure for 4 h to obtain the low shrinkage encapsulating material.

[0035] Examples 2 - Example 3

[0036] The difference from Example 1 is that the addition amounts of the components of the low shrinkage encapsulating material are different, as shown in Table 1 specifically.

[0037] Table 1 Addition amounts of the components of the low shrinkage encapsulating material in Examples 1 - 3

[0038] Example 1 Example 2 Example 3 Epoxy resin 73ml 70ml 76ml Spirocyclic expansion monomer 20g 25g 15g Boron trifluoride ethylamine 3.5g 3g 4g

[0039] Example 4

[0040] The difference from Example 1 is that the modified thermal conductive agent is replaced with a thermal conductive agent with the same addition amount.

[0041] Examples 5 - Example 6

[0042] The difference from Example 1 is that the addition amounts of the components of the spirocyclic expanding monomer are different, as shown in Table 2 specifically.

[0043] Table 2 Addition amounts of the components of the spirocyclic expanding monomer in Example 1 and Examples 5 - 6

[0044] Example 1 Example 5 Example 6 Bis(trimethylol)propane 6.5g 5g 8g Tetraethyl orthocarbonate 7.4ml 8.8ml 6ml p-Toluenesulfonic acid 0.09g 0.13g 0.05g Diethyl carbonate 2ml 1ml 3ml Potassium hydroxide 0.02g 0.01g 0.03g Modified thermal conductive agent 2.2g 2.8g 1.5g

[0045] Examples 7 - 8

[0046] It is different from Example 1 in that the addition amounts of the components of the modified thermal conductive agent are different, as specifically shown in Table 3.

[0047] Table 3 Addition amounts of the components of the modified thermal conductive agent in Example 1 and Examples 7 - 8

[0048] Example 1 Example 7 Example 8 Modified boron nitride 2g 1g 3g Sodium hexametaphosphate 0.05g 0.07g 0.03g Deionized water 70ml 90ml 50ml Sodium hydroxide solution 10ml 8ml 12ml Sodium silicate solution 11ml 12ml 10ml Dilute nitric acid solution 25ml 20ml 30ml

[0049] Examples 9 - 10

[0050] It is different from Example 1 in that the addition amounts of the components of the modified boron nitride are different, as specifically shown in Table 4.

[0051] Table 4 Addition amounts of the components of the modified boron nitride in Example 1 and Examples 9 - 10

[0052] Example 1 Example 9 Example 10 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide 0.47g 0.49g 0.45g 1-Vinylimidazole 0.2ml 0.3ml 0.1ml Absolute ethanol 5.5ml 5ml 6ml Iron(III) nitrate nonahydrate 0.13g 0.1g 0.16g Hexagonal boron nitride 1.2g 1.4g 1g

[0053] Comparative Example 1

[0054] It is different from Example 1 in that the spiro - type expansion monomer is no longer added.

[0055] Comparative Example 2

[0056] It is different from Example 1 in that the modified thermal conductive agent is no longer added.

[0057] Performance detection test

[0058] I. Curing volume shrinkage test

[0059] Three samples are respectively taken from Examples 1 - 10 and Comparative Examples 1 - 2, and a ZMD - 2 type electronic density meter is used to obtain the densities ρ1 and ρ2 of the samples before and after curing at 25°C. The volume shrinkage rate △ of the modified epoxy resin is calculated according to the formula △=(ρ2 - ρ1) / ρ1, and the average value is taken.

[0060] The detection data are shown in Table 5.

[0061] Table 5 Curing volume shrinkage test table of Examples 1 - 10 and Comparative Examples 1 - 2

[0062]

[0063]

[0064] II. Thermal conductivity and flame retardancy performance

[0065] Three samples were taken from Examples 1 - 10 and Comparative Examples 1 - 2 respectively, and the thermal conductivity was directly measured using a multifunctional rapid thermal conductivity tester; the UL94 flame retardant rating of the test samples was measured.

[0066] The test data are shown in Table 6.

[0067] Table 6 Thermal conductivity and flame retardancy performance test table of Examples 1 - 10 and Comparative Examples 1 - 2

[0068]

[0069]

[0070] Combining Example 1 and Comparative Example 1 and referring to Tables 5 - 6, it can be seen that compared with Example 1, the volume shrinkage rate of Comparative Example 1 has a significant increase. At the same time, the thermal conductivity of Comparative Example 1 has a significant decrease, and the flame retardant rating of Comparative Example 1 is HB. This shows that compared with conventional encapsulation materials, the encapsulation material added with spirocyclic expansion monomers can effectively reduce the curing shrinkage rate, and at the same time is beneficial to improving the thermal conductivity and flame retardancy of the encapsulation material.

[0071] The reason is that since the curing shrinkage rate of epoxy resin varies due to different curing agents and curing systems, generally ranging from 2 - 7%, during the curing process of the encapsulation material, the spirocyclic expansion monomer can undergo a ring-opening polymerization reaction. The original compact covalent bond connection method changes, the distance between atoms increases, the molecular conformation stretches, occupying a larger space, and the molecular structure expands to generate volume expansion, which can compensate for the shrinkage during the curing of epoxy resin.

[0072] Combining Example 1 and Comparative Example 2 and referring to Tables 5 - 6, it can be seen that compared with Example 1, the volume shrinkage rate of Comparative Example 2 has a slight increase. At the same time, the thermal conductivity of Comparative Example 2 has a significant decrease, and the flame retardant rating of Comparative Example 2 is V2. This shows that compared with the non-addition of modified thermal conductive agent, the addition of modified thermal conductive agent can effectively improve the thermal conductivity and flame retardancy of the encapsulation material, and at the same time the addition of modified thermal conductive agent is not likely to affect the low volume shrinkage of the encapsulation material.

[0073] The reason is that since bis(trimethylol)propane contains multiple hydroxyl groups and has high reaction activity, it can provide abundant active sites for subsequent reactions. It condenses with tetraethyl orthocarbonate under the catalysis of p-toluenesulfonic acid to form a spiro structure, endowing the ability of volume expansion during curing to compensate for the shrinkage of epoxy resin. Diethyl carbonate as a reaction solvent is beneficial to promoting the uniform dispersion of raw materials, and potassium hydroxide regulating the reaction process is beneficial to the complete formation of the spiro structure. The added modified thermal conductive agent can improve the thermal conductivity of the material, timely conduct out the heat generated during the curing process, reduce the shrinkage deformation caused by thermal stress, and at the same time is beneficial to improving the heat dissipation performance after encapsulation.

[0074] Combining Example 1 with Examples 2 - 3 and referring to Tables 5 - 6, it can be seen that, compared with Example 1, the volume shrinkage rate of Examples 2 and 3 has a slight increase. At the same time, the thermal conductivity of Examples 2 and 3 has a slight decrease, and the flame retardant grades of Examples 2 and 3 both remain at V0. This shows that the addition amounts of the components of the low shrinkage encapsulating material affect the low volume shrinkage and thermal conductivity of the encapsulating material to a certain extent. Therefore, the addition amounts of the components of the low shrinkage encapsulating material in Example 1 are the optimal ones.

[0075] Combining Example 1 with Example 4 and referring to Tables 5 - 6, it can be seen that, compared with Example 1, the volume shrinkage rate of Example 4 has increased, and at the same time, the thermal conductivity of Example 4 has decreased. The flame retardant grade of Example 4 is V1. This shows that, compared with adding conventional thermal conductive agents, adding modified thermal conductive agents can effectively improve the thermal conductivity and flame retardant performance of the encapsulating material, and the addition of modified thermal conductive agents is conducive to achieving low volume shrinkage of the encapsulating material to a certain extent.

[0076] Combining Example 1 with Examples 5 - 6 and referring to Tables 5 - 6, it can be seen that, compared with Example 1, the volume shrinkage rates of Examples 5 and 6 have increased, and at the same time, the thermal conductivities of Examples 5 and 6 have decreased. The flame retardant grades of Examples 5 and 6 both remain at V0. This shows that the addition amounts of the components of the spirocyclic expansion monomer affect the low volume shrinkage and thermal conductivity of the encapsulating material to a certain extent. Therefore, the addition amounts of the components of the spirocyclic expansion monomer in Example 1 are the optimal ones.

[0077] Combining Example 1 with Examples 7 - 8 and referring to Tables 5 - 6, it can be seen that, compared with Example 1, the volume shrinkage rates of Examples 7 and 8 have increased, and at the same time, the thermal conductivities of Examples 7 and 8 have decreased. The flame retardant grades of Examples 7 and 8 both remain at V0. This shows that the addition amounts of the components of the modified thermal conductive agent affect the low volume shrinkage and thermal conductivity of the encapsulating material to a certain extent. Therefore, the addition amounts of the components of the modified thermal conductive agent in Example 1 are the optimal ones.

[0078] Combining Example 1 with Examples 9 - 10 and referring to Tables 5 - 6, it can be seen that, compared with Example 1, the volume shrinkage rates of Examples 9 and 10 have increased, and at the same time, the thermal conductivities of Examples 9 and 10 have decreased. The flame retardant grades of Examples 9 and 10 both remain at V0. This shows that the addition amounts of the components of the modified boron nitride affect the low volume shrinkage and thermal conductivity of the encapsulating material to a certain extent. Therefore, the addition amounts of the components of the modified boron nitride in Example 1 are the optimal ones.

[0079] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A low shrinkage packaging material, characterized in that: Including the following ingredients: 70-76ml epoxy resin, 15-25g spiro-type expansion monomer, 3-4g boron trifluoride ethylamine.

2. The low shrinkage packaging material according to claim 1, characterized in that: The spiral ring expansion monomer comprises the following raw materials: 5-8g of di(trimethylol)propane, 6-8.8ml of tetraethyl orthocarbonate, 0.05-0.13g of p-toluenesulfonic acid, 1-3ml of diethyl carbonate, 0.01-0.03g of potassium hydroxide, and 1.5-2.8g of modified thermal conductor.

3. The low shrinkage packaging material according to claim 2, characterized in that: The preparation method of the spiral expansion monomer is as follows: 5-8g of di(trimethylol)propane and 6-8.8ml of tetraethyl orthocarbonate are weighed and added into a flask, and nitrogen protection is applied. Then, 0.05-0.13g of p-toluenesulfonic acid is added, the temperature is slowly raised to 50-70°C, and the reaction is stirred for 0.5-1.5h. Then, the temperature is lowered to 35-45°C, 1-3ml of diethyl carbonate is slowly added, the temperature is raised to 70-90°C, and the reaction is continued for 0.5-1.5h. Then, 0.01-0.03g of potassium hydroxide is added, and the reaction is continued at 75-85°C for 1-3h. Then, 1.5-2.9g of a modified thermal conductor is added, and the reaction is stirred and dispersed for 20-40min.

4. The low shrinkage packaging material according to claim 3, characterized in that: The modified thermal conductor comprises the following raw materials: 1-3 g of modified boron nitride, 0.03-0.07 g of sodium hexametaphosphate, 50-90 ml of deionized water, 8-12 ml of sodium hydroxide solution, 10-12 ml of sodium silicate solution, and 20-30 ml of dilute nitric acid solution.

5. The low shrinkage packaging material according to claim 4, characterized in that: The preparation method of the modified thermal conductor is as follows: 0.03-0.07g of sodium hexametaphosphate is weighed and dissolved in 50-90ml of deionized water, 1-3g of modified boron nitride is added while stirring, ultrasonic dispersion is performed for 20-40min, and then the mixture is moved to a constant temperature water bath with the temperature kept constant at 85-95°C, stirred, 8-12ml of sodium hydroxide solution is slowly added, and then 10-12ml of sodium silicate solution and 20-30ml of dilute nitric acid solution are slowly added dropwise, stirred for 3-7min, and then kept warm for 1-3h, filtered, rinsed with deionized water, and then dried at 95-115°C for 22-26h.

6. The low shrinkage packaging material according to claim 5, characterized in that: The modified boron nitride comprises the following raw materials: 0.45-0.49 g 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 0.1-0.3 ml 1-vinylimidazole, 5-6 ml anhydrous ethanol, 0.1-0.16 g ferric nitrate nonahydrate, 1-1.4 g hexagonal boron nitride.

7. The low shrinkage packaging material according to claim 6, characterized in that: The preparation method of the modified boron nitride comprises the following steps: weighing 0.45-0.49 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a flask, heating the mixture to 120-160° C., adding 0.1-0.3 ml of 1-vinyl imidazole, heating the mixture to 150-170° C., refluxing the mixture for 10-14 hours, cooling the mixture to 75-85° C., adding 1.5-2.5 ml of anhydrous ethanol, stirring the mixture to obtain a premixed solution, weighing 1-1.4 g of hexagonal boron nitride, dispersing the premixed solution in 1-3 ml of anhydrous ethanol, stirring the premixed solution, dispersing 0.1-0.16 g of ferric nitrate nonahydrate in 1-2 ml of anhydrous ethanol, and adding the premixed solution dropwise to the premixed solution, continuing stirring for 0.5-1.5 hours, and then centrifuging, washing, and drying the premixed solution.

8. A method for preparing a low shrinkage packaging material according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Weigh 15-25g of spiral expansion monomer and 70-76ml of epoxy resin, mix evenly, then add 3-4g of boron trifluoride ethylamine, stir, and after stirring evenly, put it into a 50-70℃ vacuum oven for degassing. After degassing until there are no bubbles, pour it into a mold preheated to 110-130℃, and then put it into a 145-155℃ oven for curing for 3-5h.

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