Copper-clad plate with high binding power and manufacturing method thereof

Abstract

The invention provides a copper-clad plate with high binding power. A resin glue solution used for manufacturing the copper-clad plate with high binding power is prepared from the following components in parts by weight: 5-30 parts of epoxy resin E-5125, 15-20 parts of organosilicone acrylic epoxy resin, 8-12 parts of a curing agent, 0.1-0.2 part of a curing accelerator, 25-30 parts of filler, 2-5 parts of a dispersing agent and 62-66 parts of a solvent. The invention also provides a manufacturing method of the copper-clad plate. The copper-clad plate provided by the invention has relatively high binding power and relatively good water resistance and heat-conducting property.

Description

Technical Field

[0001] The present invention relates to a copper clad laminate, and particularly to a copper clad laminate with high adhesion and a manufacturing method thereof. Background Art

[0002] Copper clad laminates are the main materials for manufacturing printed circuit boards (PCBs) and are also essential basic electronic materials for electronic products. With the progress of technology and the development of society, from smartphones to autonomous driving cars, from smart homes to industrial automation, the application scope of electronic products is becoming increasingly extensive, resulting in a continuous growth in the demand for copper clad laminates. Especially in the field of communication technology, the popularization of the fifth-generation mobile communication technology (5G) has not only promoted a leapfrog improvement in data transmission speed but also facilitated the rapid development of emerging fields such as the Internet of Things, remote healthcare, and virtual reality.

[0003] Copper clad laminates are generally made of reinforcing materials such as wood pulp paper or fiberglass cloth, impregnated with resin glue to form prepregs, and after combining several prepregs, copper foils are attached on one or both sides and then hot-pressed and cured to form plate-like materials. The surface of fiberglass cloth is hydrophilic, while resin glue is generally hydrophobic. Therefore, the wettability of resin glue on fiberglass cloth is very important, which gives a great change to the interface condition and has a significant impact on improving and enhancing the application performance of copper clad laminates. Poor wettability will result in incomplete close contact between the resin and fiberglass cloth, thereby affecting the adhesion and overall performance of copper clad laminates. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a copper clad laminate with high adhesion, good water resistance, and good thermal conductivity.

[0005] To solve the above technical problem, the technical solution of the present invention is as follows:

[0006] A copper clad laminate with high adhesion, the resin glue used in manufacturing the copper clad laminate with high adhesion is made of the following components in parts by weight: 25 - 30 parts of epoxy resin E - 51, 15 - 20 parts of organosilicon acrylic epoxy resin, 8 - 12 parts of curing agent, 0.1 - 0.2 parts of curing accelerator, 25 - 30 parts of filler, 2 - 5 parts of dispersant, and 62 - 66 parts of solvent.

[0007] Further, the organosilicon acrylic epoxy resin of the present invention is made by the following steps:

[0008] Mix acrylic epoxy resin, 4 - cyclooctenyltrimethoxysilane, and toluene, heat to 80°C, then dropwise add an azobisisobutyronitrile toluene solution, stir and react for 4 hours to obtain a reaction solution. After distilling off toluene from the reaction solution under reduced pressure, a reactant is obtained, and the reactant is dried to constant weight to obtain the organosilicon acrylic epoxy resin.

[0009] Further, in the preparation step of the organosilicon acrylic epoxy resin of the present invention, the azobisisobutyronitrile toluene solution is composed of azobisisobutyronitrile and toluene in a ratio of 4 mg:1 mL, and the weight ratio of the acrylic epoxy resin, 4-cyclooctenyltrimethoxysilane, toluene, and the azobisisobutyronitrile toluene solution is 5:1:2.5:10, and the drying temperature is 80 °C.

[0010] Further, the curing agent of the present invention is tetrahydrophthalic anhydride, and the curing accelerator is 2-phenylimidazole.

[0011] Further, the dispersant of the present invention is prepared by the following steps:

[0012] (1) Mix piperidine-1-sulfonyl chloride, sodium azide, and N,N-dimethylformamide, heat to 35 °C, and then stir the reaction in a water bath for 24 hours to obtain reaction solution 1. Alcohol precipitate the reaction solution 1 to obtain a reactant, filter the reactant under reduced pressure to obtain a filter residue, wash the filter residue 5 times with absolute ethanol and deionized water respectively, and then vacuum dry to constant weight to obtain a dispersant precursor;

[0013] (2) Add the dispersant precursor obtained in step (1), N,N,N',N'-tetraethyldiethylenetriamine, and cuprous bromide to N,N-dimethylformamide, stir at room temperature for 2 hours, then dropwise add propargyl alcohol, heat to 60 °C, and then stir the reaction in a water bath for 12 hours to obtain reaction solution 2. Filter the reaction solution 2 under reduced pressure to obtain a filtrate, let the filtrate stand and separate into layers, take the upper layer solution, wash the upper layer solution to neutrality, and then vacuum dry to constant weight to obtain the dispersant.

[0014] Further, in step (1) of the present invention, the ratio of piperidine-1-sulfonyl chloride, sodium azide, and N,N-dimethylformamide is 1 mmol:3 mmol:5 mL. The methanol aqueous solution with a volume fraction of 50% is used for alcohol precipitation, and the volume of this methanol aqueous solution is 10 times that of reaction solution 1. The vacuum drying temperature is 45 °C; in step (2), the ratio of the dispersant precursor obtained in step (1), N,N,N',N'-tetraethyldiethylenetriamine, cuprous bromide, N,N-dimethylformamide, and propargyl alcohol is 2 g:15 g:1.5 g:100 mL:3 g, and the vacuum drying temperature is 45 °C.

[0015] Further, the filler of the present invention is composed of equal weights of aluminum nitride and wollastonite.

[0016] Further, the solvent of the present invention is composed of equal weights of isopropyl alcohol and ethylene glycol methyl ether.

[0017] Another technical problem to be solved by the present invention is to provide a manufacturing method of the copper clad laminate with high adhesion force as described above.

[0018] To solve the above technical problems, the technical solution is as follows:

[0019] A manufacturing method of a copper clad laminate with high adhesive force, comprising the following steps:

[0020] S1. Weigh each component of the resin glue solution by weight, and stir the components at room temperature until evenly mixed to obtain the resin glue solution;

[0021] S2. Immerse the glass fiber cloth in the resin glue solution obtained in step S1 for 5 - 10 minutes, take it out and bake for 10 - 15 minutes to obtain a prepreg;

[0022] S3. Stack 2 prepregs obtained in step S2 together to get a stack, cover a copper foil on each side of the stack, and then place it in a hot press for hot pressing to obtain a copper clad laminate with high adhesive force.

[0023] Furthermore, in step S2 of the present invention, the baking temperature is 160 - 180 °C; in step S3, the hot pressing temperature is 200 - 220 °C, the pressure is 3 - 5 MPa, and the time is 1 - 2 hours.

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

[0025] 1) The present invention uses acrylic epoxy resin and 4 - cyclooctenyltrimethoxysilane as monomers to prepare organosilicon acrylic epoxy resin containing siloxane through polymerization reaction. Compared with ordinary epoxy resin and acrylic epoxy resin, the organosilicon acrylic epoxy resin prepared in the present invention has better wettability to glass fiber cloth and better water resistance itself. Therefore, it can effectively improve the adhesive force and water resistance of the copper clad laminate.

[0026] 2) The present invention prepares a dispersant precursor containing azide groups by substituting piperidine - 1 - sulfonyl chloride with sodium azide, and then reacts the dispersant precursor with N,N,N',N' - tetraethyldiethylenetriamine and propargyl alcohol through click chemistry to obtain a dispersant with hydrophilicity at one end and hydrophobicity at the other end. This dispersant can make the glass fiber cloth hydrophobic, thereby improving the compatible combination between the glass fiber cloth and the resin glue solution, and further improving the adhesive force of the copper clad laminate.

[0027] 3) The filler used in the present invention is composed of aluminum nitride and wollastonite. The former has a lower thermal conductivity and better heat resistance, and the latter has better mechanical properties and wear resistance. With the help of the dispersant, the filler composed of aluminum nitride and wollastonite can be well dispersed in the resin glue solution, thereby effectively improving the thermal conductivity, heat resistance, wear resistance and mechanical properties of the copper clad laminate. Specific Embodiments

[0028] The present invention will be described in detail below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but do not limit the present invention.

[0029] Example 1

[0030] A copper clad laminate with high adhesion, the resin adhesive solution used in manufacturing the copper clad laminate with high adhesion is made of the following components by weight: 28 parts of epoxy resin E-51, 18 parts of silicone acrylate epoxy resin, 10 parts of curing agent, 0.2 part of curing accelerator, 27 parts of filler, 4 parts of dispersant, and 65 parts of solvent. Among them, the curing agent is tetrahydrophthalic anhydride, the curing accelerator is 2-phenylimidazole, the filler is composed of equal weights of aluminum nitride and wollastonite, and the solvent is composed of equal weights of isopropyl alcohol and ethylene glycol methyl ether.

[0031] The silicone acrylate epoxy resin is made by the following steps:

[0032] Mix acrylic epoxy resin, 4-cyclooctenyltrimethoxysilane, and toluene, heat to 80 °C, and then dropwise add an azobisisobutyronitrile toluene solution composed of azobisisobutyronitrile and toluene in a ratio of 4 mg:1 mL. The weight ratio of acrylic epoxy resin, 4-cyclooctenyltrimethoxysilane, toluene, and azobisisobutyronitrile toluene solution is 5:1:2.5:10. Stir and react for 4 hours to obtain a reaction solution. After distilling off toluene from the reaction solution under reduced pressure, a reactant is obtained. The reactant is dried at 80 °C to constant weight to obtain the silicone acrylate epoxy resin.

[0033] The dispersant is made by the following steps:

[0034] (1) Mix piperidine-1-sulfonyl chloride, sodium azide, and N,N-dimethylformamide in a ratio of 1 mmol:3 mmol:5 mL, heat to 35 °C, and then stir and react in a water bath for 24 hours to obtain a reaction solution 1. Alcohol-precipitate the reaction solution 1 with its 10-fold volume of a 50% methanol aqueous solution by volume to obtain a reactant. Filter the reactant under reduced pressure to obtain a filter residue. Wash the filter residue 5 times with anhydrous ethanol and deionized water respectively, and then vacuum dry at 45 °C to constant weight to obtain a dispersant precursor;

[0035] (2) Add the dispersant precursor, N,N,N',N'-tetraethyldiethylenetriamine, and cuprous bromide obtained in step (1) into N,N-dimethylformamide. After stirring at room temperature for 2 hours, add propargyl alcohol dropwise. The ratio of the dispersant precursor, N,N,N',N'-tetraethyldiethylenetriamine, cuprous bromide, N,N-dimethylformamide, and propargyl alcohol obtained in step (1) is 2 g:15 g:1.5 g:100 mL:3 g. Heat to 60 °C and stir the reaction mixture in a water bath for 12 hours to obtain reaction solution II. Filter the reaction solution II under reduced pressure to obtain a filtrate. Let the filtrate stand for layering, and take the upper layer solution. Wash the upper layer solution until it is neutral, and then dry it under vacuum at 45 °C until a constant weight is obtained to obtain the dispersant.

[0036] The manufacturing method of Example 1 includes the following steps:

[0037] S1. Weigh each component of the resin adhesive solution by weight, and stir the components at room temperature until they are uniformly mixed to obtain the resin adhesive solution;

[0038] S2. Immerse the 2116 electronic grade fiberglass cloth in the resin adhesive solution obtained in step S1 for 8 minutes, take it out, and bake it at 170 °C for 12 minutes to obtain a prepreg with a thickness of 0.3 mm;

[0039] S3. Stack 2 prepregs obtained in step S2 together to obtain a stacked sheet. Cover each side of the stacked sheet with a copper foil with a thickness of 35 μm, and then place it in a hot press for hot pressing to obtain a copper clad laminate with high adhesion. The hot pressing temperature is 210 °C, the pressure is 4 MPa, and the time is 1.5 hours.

[0040] Example 2

[0041] For the copper clad laminate with high adhesion, the resin adhesive solution used in manufacturing the copper clad laminate with high adhesion is made of the following components by weight: 30 parts of epoxy resin E-51, 15 parts of organosilicon acrylic epoxy resin, 9 parts of curing agent, 0.1 part of curing accelerator, 25 parts of filler, 2 parts of dispersant, and 64 parts of solvent. Among them, the curing agent is tetrahydrophthalic anhydride, the curing accelerator is 2-phenylimidazole, the filler is composed of equal weights of aluminum nitride and wollastonite, the solvent is composed of equal weights of isopropanol and ethylene glycol monomethyl ether, and the preparation steps of the organosilicon acrylic epoxy resin and the dispersant are the same as those in Example 1.

[0042] The manufacturing method of Example 2 includes the following steps:

[0043] S1. Weigh each component of the resin adhesive solution by weight, and stir the components at room temperature until they are uniformly mixed to obtain the resin adhesive solution;

[0044] S2. Immerse the 2116 electronic grade fiberglass cloth in the resin adhesive solution obtained in step S1 for 5 minutes, take it out, and bake it at 180 °C for 10 minutes to obtain a prepreg with a thickness of 0.3 mm;

[0045] S3. Stack the two prepregs obtained in step S2 together to obtain a laminated sheet. Cover each side of the laminated sheet with a copper foil having a thickness of 35 μm, and then place it in a hot press for hot pressing to obtain a copper clad laminate with high adhesion. The hot pressing temperature is 220 °C, the pressure is 3 MPa, and the time is 2 hours.

[0046] Example 3

[0047] For the copper clad laminate with high adhesion, the resin adhesive used in manufacturing the copper clad laminate with high adhesion is made of the following components by weight: 27 parts of epoxy resin E-51, 16 parts of silicone acrylate epoxy resin, 8 parts of curing agent, 0.2 part of curing accelerator, 30 parts of filler, 5 parts of dispersant, and 66 parts of solvent. Among them, the curing agent is tetrahydrophthalic anhydride, the curing accelerator is 2-phenylimidazole, the filler is composed of equal weights of aluminum nitride and wollastonite, the solvent is composed of equal weights of isopropyl alcohol and ethylene glycol methyl ether, and the preparation steps of the silicone acrylate epoxy resin and the dispersant are the same as those in Example 1.

[0048] The manufacturing method of Example 3 includes the following steps:

[0049] S1. Weigh each component of the resin adhesive according to the parts by weight, and stir the components at room temperature until they are evenly mixed to obtain the resin adhesive.

[0050] S2. Immerse the 2116 electronic grade glass fiber cloth in the resin adhesive obtained in step S1 for 9 minutes, take it out and bake it at 175 °C for 14 minutes to obtain a prepreg with a thickness of 0.3 mm.

[0051] S3. Stack the two prepregs obtained in step S2 together to obtain a laminated sheet. Cover each side of the laminated sheet with a copper foil having a thickness of 35 μm, and then place it in a hot press for hot pressing to obtain a copper clad laminate with high adhesion. The hot pressing temperature is 215 °C, the pressure is 4 MPa, and the time is 1 hour.

[0052] Example 4

[0053] For the copper clad laminate with high adhesion, the resin adhesive used in manufacturing the copper clad laminate with high adhesion is made of the following components by weight: 25 parts of epoxy resin E-51, 20 parts of silicone acrylate epoxy resin, 12 parts of curing agent, 0.1 part of curing accelerator, 28 parts of filler, 3 parts of dispersant, and 62 parts of solvent. Among them, the curing agent is tetrahydrophthalic anhydride, the curing accelerator is 2-phenylimidazole, the filler is composed of equal weights of aluminum nitride and wollastonite, and the solvent is composed of equal weights of isopropyl alcohol and ethylene glycol methyl ether. The preparation steps of the silicone acrylate epoxy resin and the dispersant are the same as those in Example 1.

[0054] The manufacturing method of Example 4 includes the following steps:

[0055] S1. Weigh each component of the resin adhesive solution by weight parts, and stir the components at room temperature until they are evenly mixed to obtain the resin adhesive solution;

[0056] S2. Immerse the 2116 electronic grade glass fiber cloth in the resin adhesive solution obtained in step S1 for 10 minutes, take it out and bake it at 160 °C for 15 minutes to obtain a prepreg with a thickness of 0.3 mm;

[0057] S3. Stack 2 prepregs obtained in step S2 together to obtain a stacked sheet, cover each side of the stacked sheet with a copper foil with a thickness of 35 μm, and then place it in a hot press for hot pressing to obtain a copper clad laminate with high adhesion. The hot pressing temperature is 200 °C, the pressure is 5 MPa, and the time is 2 hours.

[0058] Comparative Example 1

[0059] The difference from Example 1 is that the silicone acrylate epoxy resin in the resin adhesive solution component is replaced by acrylate epoxy resin, and the preparation step of the silicone acrylate epoxy resin is omitted.

[0060] Comparative Example 2

[0061] The difference from Example 1 is that the dispersant is not included in the components of the resin adhesive solution, and the preparation step of the dispersant is omitted.

[0062] Experimental Example 1: Bonding Strength Test

[0063] Test reference standard / method: IPC-TM-650 2.4.8.

[0064] Test object and target: The peel strength of the copper clad laminates prepared in Examples 1-4, Comparative Example 1, and Comparative Example 2.

[0065] The higher the peel strength, the higher the bonding strength. The test results are shown in Table 1:

[0066]

[0067] Table 1

[0068] As can be seen from Table 1, the peel strengths of Examples 1-4 of the present invention are all relatively high, indicating that the present invention has relatively high bonding strength. The partial components and preparation steps used in Comparative Example 1 and Comparative Example 2 are different from those in Example 1. Compared with Example 1, the peel strength of Comparative Example 1 has decreased, indicating that compared with ordinary acrylate epoxy resin, the wettability of the silicone acrylate epoxy resin prepared by the present invention is better, and the effect of improving the bonding strength of the copper clad laminate is also better; compared with Example 1, the peel strength of Comparative Example 2 has also decreased, indicating that the dispersant prepared by the present invention can effectively improve the bonding strength of the copper clad laminate.

[0069] Experimental Example 2: Water Resistance Test

[0070] Test reference standard / method: GB / T 4722-2017 9.2.

[0071] Test object, target: water absorption rate of the copper clad laminates prepared in Examples 1-4 and Comparative Example 1.

[0072] The lower the water absorption rate, the better the water resistance. The test results are shown in Table 2:

[0073] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Water Absorption Rate (%) 0.08 0.10 0.11 0.07 0.19

[0074] Table 2

[0075] As can be seen from Table 2, the water absorption rates of Examples 1-4 of the present invention are all relatively low, indicating that the present invention has good water resistance. Some components and preparation steps used in Comparative Example 1 are different from those in Example 1. Compared with Example 1, the water absorption rate of Comparative Example 1 increases significantly, indicating that the silicone acrylate epoxy resin prepared by the present invention has a better effect on improving the water resistance of copper clad laminates compared with ordinary acrylic epoxy resins.

[0076] Experimental Example III: Thermal Conductivity Test

[0077] Test reference standard / method: ASTM D5470 (Standard Test Method for Thermal Conductivity of Thin Thermal Conductive Solid Insulating Materials).

[0078] Test object, target: thermal conductivity of the copper clad laminates prepared in Examples 1-4 and Comparative Example 2.

[0079] The higher the thermal conductivity, the better the thermal performance. The test results are shown in Table 3:

[0080]

[0081]

[0082] Table 3

[0083] As can be seen from Table 3, the thermal conductivities of Examples 1-4 of the present invention are all relatively high, indicating that the present invention has good thermal performance. Some components and preparation steps used in Comparative Example 2 are different from those in Example 1. Compared with Example 1, the thermal conductivity of Comparative Example 2 decreases, indicating that the dispersant prepared by the present invention can effectively improve the thermal conductivity of copper clad laminates.

[0084] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A copper clad laminate with high bonding strength, characterized in that: The resin glue used in manufacturing the copper-clad laminate with high bonding force is made of the following components in parts by weight: 25-30 parts of epoxy resin E-51, 15-20 parts of silicone acrylic epoxy resin, 8-12 parts of curing agent, 0.1-0.2 parts of curing accelerator, 25-30 parts of filler, 2-5 parts of dispersant and 62-66 parts of solvent.

2. The copper-clad laminate with high bonding strength according to claim 1, characterized in that: The silicone acrylic epoxy resin is prepared by the following steps: Acrylic epoxy resin, 4-cyclooctenyltrimethoxysilane and toluene are mixed, heated to 80°C, and then azobisisobutyronitrile toluene solution is added dropwise, and the mixture is stirred for reaction for 4 hours to obtain a reaction liquid, and the reaction liquid is evaporated under reduced pressure to remove toluene to obtain a reactant, and the reactant is dried to constant weight to obtain a silicone acrylic epoxy resin.

3. The copper-clad laminate with high bonding strength according to claim 2, characterized in that: In the preparation step of the silicone acrylic epoxy resin, the azobisisobutyronitrile toluene solution is composed of azobisisobutyronitrile and toluene in a ratio of 4 mg:1 mL, the weight ratio of acrylic epoxy resin, 4-cyclooctenyltrimethoxysilane, toluene, and azobisisobutyronitrile toluene solution is 5:1:2.5:10, and the drying temperature is 80°C.

4. The copper-clad laminate with high bonding strength according to claim 1, characterized in that: The curing agent is tetrahydrophthalic anhydride, and the curing accelerator is 2-phenylimidazole.

5. The copper-clad laminate with high bonding strength according to claim 1, characterized in that: The dispersant is prepared by the following steps: (1) piperidine-1-sulfonyl chloride, sodium azide, and N,N-dimethylformamide are mixed, heated to 35° C., and stirred in a water bath for 24 hours to obtain a reaction solution 1, the reaction solution 1 is precipitated with alcohol to obtain a reactant, the reactant is filtered under reduced pressure to obtain a filter residue, the filter residue is washed with anhydrous ethanol and deionized water for 5 times respectively, and then vacuum dried to constant weight to obtain a dispersant precursor; (2) The dispersant precursor obtained in step (1), N,N,N',N'-tetraethyldiethylenetriamine and cuprous bromide are added to N,N-dimethylformamide, and propargyl alcohol is added dropwise after stirring at room temperature for 2 hours. The mixture is heated to 60° C. and stirred in a water bath for 12 hours to obtain a second reaction solution. The second reaction solution is filtered under reduced pressure to obtain a filtrate. The filtrate is allowed to stand for stratification and the upper layer solution is taken. The upper layer solution is washed with water until it is neutral and then vacuum dried to a constant weight to obtain a dispersant.

6. The copper-clad laminate with high bonding strength according to claim 5, characterized in that: In the step (1), the ratio of piperidine-1-sulfonyl chloride, sodium azide and N,N-dimethylformamide is 1mmol:3mmol:5mL, a methanol aqueous solution with a volume fraction of 50% is used for alcohol precipitation, the volume of the methanol aqueous solution is 10 times that of the reaction solution 1, and the vacuum drying temperature is 45°C; in the step (2), the ratio of the dispersant precursor obtained in the step (1), N,N,N',N'-tetraethyldiethylenetriamine, cuprous bromide, N,N-dimethylformamide and propargyl alcohol is 2g:15g:1.5g:100mL:3g, and the vacuum drying temperature is 45°C.

7. The copper-clad laminate with high bonding strength according to claim 1, characterized in that: The filler consists of equal weights of aluminum nitride and wollastonite.

8. The copper-clad laminate with high bonding strength according to claim 1, characterized in that: The solvent consists of equal weights of isopropyl alcohol and ethylene glycol methyl ether.

9. A method for manufacturing a copper clad laminate with high bonding strength according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Weigh the components of the resin glue in parts by weight, and stir the components at room temperature until they are uniformly mixed to obtain a resin glue; S2. The glass fiber cloth is immersed in the resin glue obtained in step S1 for 5-10 minutes, and then taken out and baked for 10-15 minutes to obtain a prepreg; S3. Stack two prepregs obtained in step S2 together to obtain a laminate, cover both sides of the laminate with a copper foil, and then place the laminate in a hot press to obtain a copper-clad laminate with high adhesion.

10. The method for manufacturing a copper clad laminate with high bonding strength according to claim 9, characterized in that: In the step S2, the baking temperature is 160-180°C; in the step S3, the hot pressing temperature is 200-220°C, the pressure is 3-5MPa, and the time is 1-2 hours.

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