High reflectivity high thermal conductive resin composition, prepreg and copper clad laminate

Abstract

The application discloses a high-reflectivity high-thermal-conductivity resin composition, which comprises the following components in parts by weight: liquid crystal epoxy resin 40-80 parts, base epoxy resin 30-70 parts, curing agent 70-150 parts, titanium dioxide 120-180 parts, thermal conductive filler 230-450 parts, accelerator 0.1-5 parts and coupling agent 0.1-3 parts. By selecting the liquid crystal epoxy resin with a specific structure, the rigid center core of triphenylene ring structure is introduced into the molecule, and the liquid crystal phase is given relatively high thermal stability; the liquid crystal epoxy resin is self-assembled to form ordered columnar phase and lamellar phase through the strong pi-pi stacking effect between the mesogenic units of the condensed benzene ring structure, the conduction of electric charge and the transmission of energy are improved, the thermal conductivity of the resin composition is improved, the liquid crystal epoxy resin has six flexible side chains, the flexibility of the molecular chain segment is increased, the triphenylene disc-shaped liquid crystal molecules formed by the combination of the two have high content of two-dimensional aromatic disc-shaped structure in the crosslinked network after curing, and a continuous thermal conductive network is formed with the filler.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive resins, and in particular to a high-reflectivity, high-thermal-conductivity resin composition, a prepreg, and a copper-clad laminate. Background Technology

[0002] Light-emitting diodes (LEDs) are semiconductor devices that can directly convert electrical energy into light energy. They are characterized by fast response, low power consumption, long lifespan, small size, and durability, and are widely used in lighting, displays, and signal indicators. As LED lighting technology evolves towards multi-functional, miniaturized, high-efficiency, highly integrated, and multi-layered support structures, it inevitably generates a significant amount of heat. If this heat is not dissipated in a timely manner, it can lead to changes in the dimensional stability of the substrate, decreased heat resistance, and reduced reliability. Therefore, white PCB boards used for LED packaging, while possessing high reflectivity, also place higher demands on their heat dissipation performance.

[0003] Because traditional epoxy resins have low intrinsic thermal conductivity, ordinary FR4 white copper-clad laminates made from them have low thermal conductivity, only 0.25 W / mK, which cannot meet the heat dissipation requirements of LED packaging. To improve the thermal conductivity of copper-clad laminates, a large amount of thermally conductive filler is usually added. However, as the filler ratio increases, the thermal conductivity of the copper-clad laminate also increases, leading to decreased peel strength, increased brittleness, and deterioration in heat resistance, processability, and insulation performance. Therefore, it is necessary to propose a new solution to address these problems. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the prior art, and its main objective is to provide a high reflectivity thermally conductive resin composition, a prepreg, and a copper-clad laminate, which can effectively solve the problem that the existing white copper-clad laminate has a low thermal conductivity, and that increasing the filler ratio will lead to a deterioration in other properties such as heat resistance and processing performance of the board.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A high-reflectivity, high-thermal-conductivity resin composition, by weight, comprises the following components: 40-80 parts of liquid crystal epoxy resin, 30-70 parts of base epoxy resin, 70-150 parts of curing agent, 120-180 parts of titanium dioxide, 230-450 parts of thermally conductive filler, 0.1-5 parts of accelerator, and 0.1-3 parts of coupling agent; wherein the structural formula of the liquid crystal epoxy resin is as follows: .

[0006] As a preferred embodiment, the base epoxy resin is one or more of hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A type phenolic epoxy resin, and bisphenol F type phenolic epoxy resin.

[0007] As a preferred embodiment, the curing agent is at least one selected from hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, styrene-maleic anhydride copolymer, methylphthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and trimellitic anhydride.

[0008] As a preferred embodiment, the titanium dioxide is surface-treated rutile titanium dioxide.

[0009] As a preferred embodiment, the thermally conductive filler is at least one selected from alumina, aluminum nitride, boron nitride, silicon carbide, and magnesium oxide.

[0010] As a preferred embodiment, the promoter is at least one selected from imidazole, 1-benzylphenyl-2-ethylimidazolium, 2-methylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 1-aminoethyl-2-methylimidazolium, and 1-cyanoethylimidazolium.

[0011] As a preferred embodiment, the coupling agent is at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

[0012] As a preferred embodiment, the total weight parts of the liquid crystal epoxy resin and the base epoxy resin are 100 parts.

[0013] A prepreg is prepared from the aforementioned high reflectivity and high thermal conductivity resin composition.

[0014] A copper-clad laminate made from the aforementioned prepreg.

[0015] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution: By selecting a liquid crystal epoxy resin with a specific structure and introducing a benzophenanthrene ring structure as a rigid central core into the molecule, the liquid crystal phase is endowed with high thermal stability, improving the heat resistance of the resin composition. Furthermore, through the strong π-π stacking effect between the mesocrystalline units of the fused benzene ring structure, the liquid crystal epoxy resin can easily enable the liquid crystal molecules to self-assemble into ordered columnar and layered phases, greatly improving charge conduction and energy transfer, reducing phonon scattering, and improving the thermal conductivity of the resin composition. In addition, the liquid crystal epoxy resin has 6 flexible side chains, increasing the flexibility of the molecular chain segments. The benzophenanthrene disk-shaped liquid crystal molecules formed by the combination of the two have a high content of two-dimensional aromatic disk-shaped structures in their cured crosslinked network, and form a continuous thermally conductive network with the filler. Ultimately, the resulting resin composition has excellent thermal conductivity, high reflectivity, and good flexibility, and can be made into a carrier board suitable for LED packaging, meeting the requirements of various Mini LED circuit board backlight applications and high thermal conductivity copper-clad laminates.

[0016] To more clearly illustrate the effects of the present invention, the present invention will be described in detail below with reference to specific embodiments. Detailed Implementation

[0017] This invention discloses a high-reflectivity, high-thermal-conductivity resin composition, comprising, by weight, the following components: 40-80 parts of liquid crystal epoxy resin, 30-70 parts of base epoxy resin, 70-150 parts of curing agent, 120-180 parts of titanium dioxide, 230-450 parts of thermally conductive filler, 0.1-5 parts of accelerator, and 0.1-3 parts of coupling agent; wherein, the structural formula of the liquid crystal epoxy resin is as follows: .

[0018] Specifically, the base epoxy resin is one or more of hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A type phenolic epoxy resin, and bisphenol F type phenolic epoxy resin; the curing agent is at least one of hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, styrene-maleic anhydride copolymer, methylphthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and trimellitic anhydride; the titanium dioxide is surface-treated rutile titanium dioxide; and the thermally conductive filler is oxygen. The liquid crystal epoxy resin comprises at least one of aluminum oxide, aluminum nitride, boron nitride, silicon carbide, and magnesium oxide; the accelerator is at least one of imidazole, 1-benzylphenyl-2-ethylimidazolium, 2-methylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 1-aminoethyl-2-methylimidazolium, and 1-cyanoethylimidazolium; the coupling agent is at least one of silane coupling agent, titanate coupling agent, and aluminate coupling agent; the total weight parts of the liquid crystal epoxy resin and the base epoxy resin are 100 parts; and the preparation method of the liquid crystal epoxy resin is as follows: 1. Under an ice bath and argon atmosphere, 10-undecene-1-ol was dissolved in anhydrous pyridine. Then, p-methylbenzenesulfonyl chloride was added to the solution, and the mixture was stirred and mixed in an ice bath for 2 hours. The reaction was carried out at 3-5°C for 24 hours. Then, ice water was added to the solution, and anhydrous diethyl ether was used for extraction. The organic layer was successively acid-washed with 18wt% hydrochloric acid solution and washed with water. Then, it was dried with anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. After drying in a vacuum drying oven for 24 hours, product 1 was obtained. Product 1 is a colorless oily liquid.

[0019] 2. Dissolve catechol in 70% H2SO4 aqueous solution, and slowly add (NH4)2S2O8 while stirring. React for 8 hours. After the reaction is complete, filter to obtain solid product. Wash with distilled water and dry in a vacuum drying oven to obtain product 2, which is a black solid.

[0020] 3. Dissolve product 1 and product 2 in DMF. Add K2CO3 and KI to the mixture under stirring and react at 85°C for 24 h. After the reaction, remove the solvent DMF by rotary evaporation. Extract the solid residue with DCM, wash with NaHCO3 aqueous solution and distilled water, dry with anhydrous Na2SO4, remove DCM by rotary evaporation, and finally dry in a vacuum drying oven for 12 h to obtain product 3. 4. Dissolve product 3 in DCM to obtain a mixed solution. Then dissolve m-chloroperoxybenzoic acid in another DCM and add it dropwise to the above mixed solution. Under stirring and at a temperature of 60°C, continue the reaction for 60 h. After the reaction, wash the organic phase with Na2SO3 aqueous solution, saturated NaCl aqueous solution and distilled water. Then, remove the solvent DCM by rotary evaporation. Finally, dry in a vacuum drying oven for 12 h to obtain liquid crystal epoxy resin. The thermal conductivity of the liquid crystal epoxy resin prepared by this method is tested to be 0.342 W / mk.

[0021] The present invention also discloses a semi-cured sheet, which is made from the aforementioned high reflectivity and high thermal conductivity resin composition. The specific preparation steps are as follows: First, the above raw material components are mixed according to the composition, and then mixed evenly by stirring to obtain a resin solution. Next, 2116 glass cloth is immersed in the resin solution, and then placed in an oven and baked at a temperature of 165-171°C for 3-5 minutes to obtain the semi-cured sheet.

[0022] The present invention also discloses a copper-clad laminate, which is made from the aforementioned prepreg. The manufacturing process is as follows: two prepregs made from 2116 glass cloth are selected, and a 12μm thick HTE copper foil is covered on each of the top and bottom surfaces. The laminates are then placed in a laminator for hot pressing to obtain the laminate. This preparation method is used in several subsequent embodiments, and the copper-clad laminates obtained are subjected to performance testing.

[0023] The raw materials used in the following embodiments and comparative examples are shown in Table 1.

[0024]

[0025] Table 1 The raw material ratios of several embodiments and comparative examples are shown in Table 2.

[0026]

[0027] Table 2 Performance tests were conducted on the above embodiments and comparative examples. The test methods are as follows, and the test results are shown in Table 3.

[0028] Thermal conductivity: tested according to ASTM D5470-2017 method.

[0029] Glass transition temperature (Tg): Tested using dynamic thermomechanical analysis (DMA).

[0030] Peel strength (PS): Tested according to IPC-TM-650 2.4.9 method.

[0031] Reflectance: After etching the substrate, the initial reflectance of the sample was measured at 450 nm using a spectrophotometer according to JIS Z-8722.

[0032]

[0033] Table 3 Analysis of the above data shows that Examples 1-7 exhibit high initial reflectivity at room temperature, with thermal conductivity all above 1.4 W / m•K. Furthermore, Examples 1-7 demonstrate high peel strength, fully meeting the requirements for white laminates used in LED packaging. Comparing Example 7 with Comparative Examples 1 and 2, Example 7 uses a blend of base epoxy resin and liquid crystal epoxy resin, while Comparative Examples 1 and 2 use either base epoxy resin or liquid crystal epoxy resin individually, with the proportions of other components remaining the same. Although Comparative Example 1 achieves superior initial reflectivity, its thermal conductivity and PS (polystyrene) are poor, with thermal conductivity only half that of Example 7, making it unsuitable for LED packaging. While Comparative Example 2 possesses high thermal conductivity and PS, the presence of numerous aromatic ring structures in its resin system results in a low initial reflectivity of the copper-clad laminate after high-temperature pressing, failing to meet the requirements for LED packaging. The reflectivity requirements of the package were compared with those of Comparative Examples 2 and 3. Comparative Examples 2 and 3 differed only in the proportion of compound fillers. In Comparative Example 3, the proportion of alumina was higher. The increase in alumina led to a decrease in the thermal conductivity and initial reflectivity of Comparative Example 3. In Examples 1 and 7, the proportion of alumina in Example 1 was higher, and the thermal conductivity of Example 1 also decreased. However, the initial reflectivity was improved, producing an unexpected technical effect. This also shows that the liquid crystal epoxy resin and the base epoxy resin were not simply mixed physically to obtain the resin composition, but a chemical reaction occurred, thereby changing the structure and properties of the resin system. As a result, the initial reflectivity of the resin composition obtained in Example 1 did not decrease when the proportion of alumina was increased, but instead achieved a significant increase.

[0034] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A high-reflectivity, high-thermal-conductivity resin composition, characterized in that: By weight, it comprises the following components: 40-80 parts liquid crystal epoxy resin, 30-70 parts base epoxy resin, 70-150 parts curing agent, 120-180 parts titanium dioxide, 230-450 parts thermally conductive filler, 0.1-5 parts accelerator, and 0.1-3 parts coupling agent; wherein, the structural formula of the liquid crystal epoxy resin is as follows: 。 2. The high reflectivity and high thermal conductivity resin composition according to claim 1, characterized in that: The base epoxy resin is one or more of the following: hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A type phenolic epoxy resin, and bisphenol F type phenolic epoxy resin.

3. The high reflectivity and high thermal conductivity resin composition according to claim 1, characterized in that: The curing agent is at least one of hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, styrene-maleic anhydride copolymer, methylphthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and trimellitic anhydride.

4. The high reflectivity and high thermal conductivity resin composition according to claim 1, characterized in that: The titanium dioxide is surface-treated rutile titanium dioxide.

5. The high reflectivity and high thermal conductivity resin composition according to claim 1, characterized in that: The thermally conductive filler is at least one of alumina, aluminum nitride, boron nitride, silicon carbide, and magnesium oxide.

6. The high reflectivity and high thermal conductivity resin composition according to claim 1, characterized in that: The accelerator is at least one selected from imidazole, 1-benzylphenyl-2-ethylimidazol, 2-methylimidazol, 2-ethyl-4-methylimidazol, 2-phenylimidazol, 1-aminoethyl-2-methylimidazol, and 1-cyanoethylimidazol.

7. The high reflectivity and high thermal conductivity resin composition according to claim 1, characterized in that: The coupling agent is at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

8. The high reflectivity and high thermal conductivity resin composition according to claim 1, characterized in that: The total weight of the liquid crystal epoxy resin and the base epoxy resin is 100 parts.

9. A semi-cured sheet, characterized in that: It is made from the high reflectivity and high thermal conductivity resin composition according to any one of claims 1-8.

10. A copper-clad laminate, characterized in that: It is made from the prepreg as described in claim 9.

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