Method for manufacturing cured product and metal foil layer substrate

Abstract

The present invention discloses a manufacturing method of a cured product and a metal foil layer substrate. The manufacturing method of the cured product includes: preparing a resin composition; coating the resin composition onto a metal substrate; curing the resin composition at a temperature of 70°C to 200°C to form a prepreg; and hot-pressing the prepreg to form a cured product. The resin composition includes: 20 to 40 parts by weight of an epoxy resin, 40 to 60 parts by weight of a modified benzoxazine resin, 2 to 10 parts by weight of a maleimide resin, and 25 to 50 parts by weight of a filler; wherein, the modified benzoxazine resin has a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group, and based on 100 weight percentages of the total weight of the modified benzoxazine resin, the proportion of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group is 10 to 20 weight percentages.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a cured product and a metal foil layer substrate, and particularly to a method for manufacturing a cured product and a metal foil layer substrate that does not have oily substances floating out at high temperatures. Background Art

[0002] Benzoxazine resin is a thermosetting resin with a structure similar to phenolic resin, and the properties of benzoxazine resin are superior to those of traditional phenolic resins. For example, benzoxazine resin has a low moisture absorption rate and good mechanical properties and dielectric properties.

[0003] During the curing process, benzoxazine resin does not release small molecule by-products, and the volume shrinkage rate after curing is low. Therefore, benzoxazine resin has a wide range of applications and can also be mixed with other types of resins, especially can be applied to the production of metal foil layer substrates.

[0004] DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) is a flame retardant with excellent heat resistance and flame retardancy. Moreover, DOPO flame retardant can be blended with other thermosetting resins, inorganic fillers or fibers to form a composite material. Therefore, in the prior art, this composite material is usually used to manufacture metal foil layer substrates.

[0005] However, in a high-temperature environment, DOPO flame retardant will thermally decompose into phosphoric acid, metaphosphoric acid or pyrophosphoric acid-containing phosphoric acids. These phosphoric acid-containing substances are prone to react with copper and oily substances will float out on the surface of the metal foil layer substrate, resulting in the quality of the metal foil layer substrate being affected.

[0006] Therefore, how to improve the composition to avoid the floating out of oily substances while enhancing the heat resistance and flame retardancy of the composite material has become one of the important issues to be solved in this field. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for manufacturing a cured product and a metal foil layer substrate in view of the deficiencies of the prior art.

[0008] To solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a method for manufacturing a cured product. The method for manufacturing a cured product includes: preparing a resin composition; coating the resin composition onto a metal substrate; curing the resin composition at a temperature of 70°C to 200°C to form a semi-cured film; and hot-pressing the semi-cured film to form a cured product. The resin composition includes: 20 to 40 parts by weight of an epoxy resin, 40 to 60 parts by weight of a modified benzoxazine resin, 2 to 10 parts by weight of a maleimide resin, and 25 to 50 parts by weight of a filler. The modified benzoxazine resin has a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group. Based on 100 weight percentages of the total weight of the modified benzoxazine resin, the proportion of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group is 10 to 20 weight percentages.

[0009] Preferably, the synthesis steps of the modified benzoxazine resin include: adding a DOPO group-containing compound to a benzoxazine resin, heating and dissolving at a temperature of 55°C to 95°C to form a reactant solution; and adding a diisocyanate to the reactant solution and reacting at a temperature of 120°C to 140°C to generate the modified benzoxazine resin.

[0010] Preferably, the DOPO group-containing compound is grafted onto the main chain of the benzoxazine resin via a diisocyanate compound.

[0011] Preferably, the phosphorus atom content in the DOPO group-containing compound is 12 weight percentages to 20 weight percentages.

[0012] Preferably, the DOPO group-containing compound is represented by formula (I):

[0013]

[0014] Preferably, the diisocyanate compound is selected from the group consisting of isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, hexamethylene diisocyanate, and combinations thereof.

[0015] Preferably, the benzoxazine resin is a bisphenol A-type modified benzoxazine resin, a bisphenol F-type modified benzoxazine resin, a diamine-type modified benzoxazine resin, or a combination thereof.

[0016] Preferably, the modified benzoxazine resin has a substituent represented by formula (II):

[0017]

[0018] Preferably, the phosphorus atom content in the modified benzoxazine resin is 1 weight percentage to 2 weight percentages.

[0019] To solve the above technical problems, another technical solution adopted by the present invention is to provide a manufacturing method of a metal foil layer substrate. The manufacturing method of the metal foil layer substrate includes formulating a resin composition; coating the resin composition onto a metal substrate; curing the resin composition at a temperature of 70°C to 200°C to form a semi-cured film; disposing a printed circuit board on the semi-cured film, and obtaining a metal foil layer substrate after hot pressing. The resin composition includes: 20 to 40 parts by weight of an epoxy resin, 40 to 60 parts by weight of a modified benzoxazine resin, 2 to 10 parts by weight of a maleimide resin, and 25 to 50 parts by weight of a filler. The modified benzoxazine resin has a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group. Based on the total weight of the modified benzoxazine resin being 100 weight percentages, the proportion of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group is 10 to 20 weight percentages.

[0020] One beneficial effect of the present invention is that the cured product and the manufacturing method of the metal foil layer substrate provided by the present invention can achieve the effect of preventing oily substances from floating out through the technical solutions of "the resin composition includes 40 to 60 parts by weight of a modified benzoxazine resin", "the modified benzoxazine resin has a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group", and "the proportion of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group is 10 to 20 weight percentages".

[0021] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the provided drawings are only for reference and illustration, and are not used to limit the present invention. Description of the Drawings

[0022] Figure 1 It is a process flow chart for synthesizing the modified benzoxazine resin of the present invention.

[0023] Figure 2 It is a manufacturing schematic diagram of the cured product of the present invention.

[0024] Figure 3 It is a process flow chart of the manufacturing method of the cured product of the present invention.

[0025] Figure 4 It is a manufacturing schematic diagram of the metal foil layer substrate of the present invention.

[0026] Figure 5 It is a process flow chart of the manufacturing method of the metal foil layer substrate of the present invention. Detailed Embodiments

[0027] The following is an embodiment of the "manufacturing method of a cured product and a metal foil layer substrate" disclosed in the present invention through specific examples, and those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. Additionally, the drawings of the present invention are only for simple schematic illustration and are not drawn according to actual dimensions, which is hereby stated in advance. The following embodiments will further detail the related technical content of the present invention, but the disclosed content is not intended to limit the protection scope of the present invention. In addition, the term "or" used herein should, depending on the actual situation, possibly include any one or a combination of more of the associated listed items.

[0028] The cured product and the metal foil layer substrate of the present invention are made using a resin composition. The cured product formed by the resin composition will not have oily substances floating out under high-temperature conditions and is suitable for manufacturing a metal foil layer substrate.

[0029] In the present invention, the resin composition contains 20 to 40 parts by weight of an epoxy resin, 40 to 60 parts by weight of a modified benzoxazine resin, 2 to 10 parts by weight of a maleimide resin, and 25 to 50 parts by weight of a filler. In this way, the resin composition and the metal foil layer substrate of the present invention can have good heat resistance and flame retardancy and will not have oily substances floating out at high temperatures.

[0030] It is worth noting that the added modified benzoxazine resin in the present invention has a DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) group. In this way, the addition of the modified benzoxazine resin can improve the heat resistance and flame retardancy of the resin composition and the metal foil layer substrate, and thus achieve the effect of improving the characteristics of the metal foil layer substrate.

[0031] Specifically, taking the total weight of the modified benzoxazine resin as 100 weight percentages, the proportion of the DOPO group in the modified benzoxazine resin is 10 to 20 weight percentages. In some embodiments, the proportion of the DOPO group in the modified benzoxazine resin can be 12 weight percentages, 14 weight percentages, 16 weight percentages, or 18 weight percentages. Preferably, the proportion of the DOPO group in the modified benzoxazine resin is 15 to 19 weight percentages.

[0032] To ensure that the resin composition and the metal foil substrate have good heat resistance and flame retardancy, based on the total weight of the modified benzoxazine resin being 100 weight percentages, the content of phosphorus atoms in the modified benzoxazine resin is 1 weight percentage to 2 weight percentages. Preferably, the content of phosphorus atoms in the modified benzoxazine resin is 1.1 weight percentages to 1.5 weight percentages.

[0033] In an exemplary embodiment, the modified benzoxazine resin is formed by reacting a DOPO-based compound, a diisocyanate compound, and a benzoxazine resin.

[0034] In the molecular structure of the modified benzoxazine resin, the DOPO-based compound is grafted onto the main chain of the benzoxazine resin via the diisocyanate compound. That is, the two isocyanate groups of the diisocyanate compound are respectively bonded to the DOPO-based compound and the benzoxazine resin.

[0035] Specifically, the content of phosphorus atoms in the DOPO-based compound is 6 weight percentages to 12 weight percentages. In an exemplary embodiment, the DOPO-based compound is as shown in formula (I):

[0036]

[0037] The diisocyanate compound is an aliphatic diisocyanate, and the weight average molecular weight of the diisocyanate compound is 150 g / mol to 280 g / mol. Selecting a diisocyanate compound within this molecular weight range is beneficial for the grafting reaction to proceed. Specifically, the diisocyanate compound can be selected from the group consisting of isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, hexamethylene diisocyanate, and combinations thereof. However, the present invention is not limited thereto.

[0038] As mentioned above, the DOPO-based compound is grafted onto the benzoxazine resin by reacting with the isocyanate group of the diisocyanate compound. Therefore, after the DOPO-based compound shown in formula (I) reacts with the diisocyanate compound, a substituent as shown in formula (II) is formed. That is, the modified benzoxazine resin may have the substituent shown in formula (II):

[0039]

[0040] In the present invention, the type of benzoxazine resin used is not limited, as long as it has a DOPO group, it is the modified benzoxazine resin of the present invention. For example, the benzoxazine resin can be a bisphenol A type benzoxazine resin, a bisphenol F type benzoxazine resin, a diamine type benzoxazine resin, or a combination thereof.

[0041] In an exemplary embodiment, when the benzoxazine resin is a bisphenol A-modified benzoxazine resin and is grafted with the substituents represented by the above formula (II), the modified benzoxazine resin can be represented as shown in formula (III): It varies depending on the type of diisocyanate compound used.

[0042] In formula (III), is formed by the reaction of primary aniline and varies depending on the type of primary aniline used. The amino group in the primary aniline can be located at the molecular end or grafted to the molecular side chain. In addition to the amino group, the primary aniline can also have other substituents, such as: alkyl group, halogen atom or hydrogen atom. Specifically, the primary aniline can be selected from the group consisting of: aniline, 4-methylaniline, 4-bromoaniline and 4-isopropylaniline.

[0043] Regarding the specific synthesis steps of the modified benzoxazine resin, please refer to Figure 1 as shown.

[0044] First, dissolve 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in a solvent and add maleic anhydride for reaction to form a DOPO group-containing compound (step S1). Add the DOPO group-containing compound to the benzoxazine resin and heat and dissolve it at a temperature of 55°C to 95°C to form a reactant solution (step S2). Then, add diisocyanate to the reactant solution and react at a temperature of 120°C to 140°C to produce the modified benzoxazine resin (step S3).

[0045] The following Synthesis Example 1 specifically illustrates the synthesis method of the DOPO group-containing compound (corresponding to the above step S1). The following Synthesis Examples 2-1 to 2-6 specifically illustrate the synthesis methods of the modified benzoxazine resins of Samples 1 to 6 (corresponding to the above steps S2 and S3).

[0046] [Synthesis Example 1]

[0047] Install a heating device, a thermometer, a stirrer, a condenser tube and a nitrogen inlet tube on a separable reaction flask with a capacity of 3 liters. Add 400 ml of toluene and 400 ml of tetrahydrofuran (solvent) to the separable reaction flask. Add 216 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to the separable reaction flask and stir at a temperature of 80°C until completely dissolved.

[0048] Then, under a nitrogen atmosphere, gradually add 98 g of maleic anhydride within 60 minutes. After raising the temperature to the reflux temperature of the solvent, react at this reflux temperature for 6 hours.

[0049] After the reaction is completed and the temperature drops to room temperature, the DOPO-based compound (DOPO-MAH) represented by the above formula (I) can be obtained through filtration, washing, and drying. Specifically, when washing the DOPO-based compound, a mixture of 400 g of tetrahydrofuran / ethanol with a volume ratio of 1:1 is used.

[0050] [Synthesis Examples 2-1 to 2-6]

[0051] Take 200 g of benzoxazine resin and 600 g of toluene, add them to a separable reaction flask, and stir evenly at a temperature of 50 °C to 70 °C until dissolved. While stirring, gradually add the DOPO-based compound (DOPO-MAH) prepared in Synthesis Example 1 within 20 minutes, and heat and dissolve at a temperature of 55 °C to 95 °C to form a reactant solution. Then, add a diisocyanate compound to the reactant solution and react at a temperature of 120 °C to 140 °C for 1 hour to produce the modified benzoxazine resin of the present invention.

[0052] Table 1 lists the types and grams of the DOPO-based compound, diisocyanate compound, and benzoxazine resin in Synthesis Examples 2-1 to 2-6. The diisocyanate can be isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), or a combination thereof. The benzoxazine resin can be bisphenol A type benzoxazine resin (BPA-BZ), bisphenol F type benzoxazine resin (BPF-BZ), or diamine type benzoxazine resin (ODA-BZ, MDA-BZ).

[0053] Table 1

[0054]

[0055]

[0056] Regarding the manufacturing schematic diagram of the cured product, please refer to Figure 2 as shown.

[0057] First, prepare a resin composition containing the aforementioned modified benzoxazine resin, and coat the resin composition on a metal substrate 10 to form a resin film 20. Then, cure the resin film 20 at a temperature of 70 °C to 200 °C to form a semi-cured film 20'. After hot pressing the semi-cured film 20', a cured product 20'' can be obtained.

[0058] For the specific manufacturing steps of the cured product, please refer toFigure 3 as shown

[0059] Prepare a resin composition, which includes a modified benzoxazine resin, an epoxy resin, a maleimide resin, and a filler (step S4). Coat the resin composition onto a metal substrate (step S5). Cure the resin composition at a temperature of 70°C to 200°C to form a semi-cured film (step S6). Hot press the semi-cured film to form a cured product (step S7).

[0060] For the manufacturing schematic diagram of the metal foil laminate substrate, please refer to Figure 4 as shown

[0061] First, prepare a resin composition containing the aforementioned modified benzoxazine resin, and coat the resin composition onto a metal substrate 10 to form a resin film 20. Then, cure the resin film 20 at a temperature of 70°C to 200°C to form a semi-cured film 20'. Place a printed circuit board 30 on the semi-cured film 20' and perform hot pressing, so that the semi-cured film 20' forms a cured product 20", and a metal foil laminate substrate can be obtained.

[0062] For the specific manufacturing steps of the metal foil laminate substrate, please refer to Figure 5 as shown

[0063] Steps S4 to S6 in the manufacturing steps of the metal foil laminate substrate are the same as steps S4 to S6 in the manufacturing steps of the cured product, so they will not be elaborated here. After forming the semi-cured film (step S6), place a printed circuit board on the semi-cured film to form a stacked structure (step S7'). Hot press the stacked structure so that the semi-cured film forms a cured product, and a metal foil laminate substrate is obtained (step S8').

[0064] Regardless of the manufacturing method of the above-mentioned cured product or the metal foil laminate substrate, after the steps of curing and hot pressing the resin composition, a cured product will be formed. Since the present invention controls the proportion of DOPO groups in the modified benzoxazine resin, by adding an appropriate amount of phosphorus atoms, the heat resistance and flame retardancy of the cured product can be improved.

[0065] To illustrate the characteristic advantages of the cured product and the metal foil laminate substrate of the present invention, according to the foregoing steps, manufacture metal foil laminate substrates of Examples 1 to 6 (E1 to E6) and Comparative Examples 1 to 4 (C1 to C4).

[0066] The resin compositions of Examples 1 to 6 and Comparative Examples 1 to 4 contain different types and contents of resins (for the specific components and contents, please refer to Table 2) to compare the effects of different resin compositions on the characteristics of the metal foil laminate substrate. The differences between Examples 1 to 6 and Comparative Examples 1 to 4 are as follows: The benzoxazine resins (BPA-BZ, ODA-BZ) added in Comparative Examples 1 to 4 are unmodified and do not have DOPO groups.

[0067] [Examples 1 to 6]

[0068] Examples 1 to 6 (E1 to E6) were prepared by adding at least one of the modified benzoxazine resins and maleimide resins in Samples 1 to 6 to 40 g of a solvent (methyl ethyl ketone) according to the component contents listed in Table 2 and completely dissolving them. Subsequently, epoxy resins (o-cresol novolac epoxy resin (CNE epoxy), bisphenol A novolac epoxy resin (BNE epoxy), and bisphenol A epoxy resin (BPA epoxy)), toughening agents (liquid polybutadiene), and flame retardants were added and uniformly mixed and dissolved using a homogenizer. After complete dissolution, a filler (silica) was added, and stirring and dispersion were continuously performed using a homogenizer to complete the preparation of the resin composition.

[0069] An E-glass substrate (model: E 2116) was immersed in the resin composition and baked at 80 °C for 3 minutes, and then baked at 180 °C for 7 minutes. After drying, a prepreg film was obtained. Four prepreg films were laminated, and a metal layer was provided on each side of the laminated structure to form a laminated structure. The laminated structure was sent to a hot press for hot pressing and curing. The set conditions of the hot press were as follows: heating to 200 °C to 220 °C at a heating rate of 3.0 °C per minute, and hot pressing for 180 minutes at a pressure of 15 kg / cm² (initial pressure 8 kg / cm²) at a temperature of 200 °C to 220 °C to obtain a metal foil laminate substrate.

[0070] [Characteristic Tests]

[0071] Transition glass temperature (Tg): The transition glass temperature of the metal foil laminate substrate was measured using a thermal mechanical analyzer (TMA).

[0072] Coefficient of thermal expansion (CTE): According to the specification of IPC-TM-650 2.4.24.5, the coefficient of thermal expansion in the z-axis direction (z-CTE) of the metal foil laminate substrate was measured in the temperature range of 50 °C to 260 °C using a thermal mechanical analyzer.

[0073] Peel strength: The metal foil laminate substrate was first dried, and then the external force required to vertically peel up a 1 / 8-inch-wide copper foil (metal substrate) was measured to quantify the peel strength of the metal foil laminate substrate.

[0074] Heat resistance: First, dry the metal foil layer substrate, then immerse the metal foil layer substrate in a soldering bath at 300 °C for 100 seconds, and repeat the immersion 3 times. If the appearance of the metal foil layer substrate remains unchanged, it is represented by "○". If there are bubbles or bulges on the appearance of the metal foil layer substrate, it is represented by "×".

[0075] Flammability (Flaming test, UL94): According to the flammability test standard of UL94, the vertical burning method is used to determine the self-ignition time, self-ignition speed, and the state of the particles dropped after the plastic material standard test piece is burned by the flame, so as to determine the flammability grade of the plastic material. And according to the quality of the flammability grade, they are evaluated as HB, V-2, V-1, V-0, and 5V in turn, where 5V is the highest flammability grade. In the test method of UL94, the plastic material burns vertically on the flame, and each ten seconds is a test cycle. The steps are as follows. Step 1: Put the test piece into the flame for ten seconds and then remove it, and measure the continuous burning time (T1) of the test piece after removal. Step 2: When the flame of the test piece goes out, put it into the flame for ten seconds and then remove it, and then measure the continuous burning time (T2) of the test piece after removal. Step 3: Repeat the experiment several times and take the average value. Step 4: Calculate the total of T1 + T2. The requirements for the V-0 grade are: the average of T1 and the average of T2 shall not exceed 10 seconds, and the total of T1 and T2 shall not exceed 50 seconds.

[0076] Test for floating of oily substances: Cut the metal foil layer substrate into square samples with a side length of 10 cm.

[0077] Bake in an oven at 200 °C for 120 minutes, and then observe whether there are oily substances floating out.

[0078]

[0079]

[0080] As can be seen from the results in Table 2, compared with Comparative Examples 1 to 4, adding the modified benzoxazine resin of the present invention can improve the heat resistance and flammability of the metal foil layer substrate, and can prevent oily substances from floating out in a high-temperature environment, achieving the effect of improving the quality of the metal foil layer substrate.

[0081] Moreover, the metal foil layer substrate of the present invention can have good heat resistance and flammability. Specifically, the glass transition temperature of the metal foil layer substrate is 170 °C to 185 °C, and the coefficient of thermal expansion of the metal foil layer substrate in the z direction is 2.5% to 3.0%. Therefore, the metal foil layer substrate can withstand a higher processing temperature.

[0082] As can be seen from the results in Table 2, the epoxy resin of the present invention may include cresol novolac epoxy resin (CNE resin), bisphenol A novolac epoxy resin (BNE resin), and bisphenol A epoxy resin. Based on the total weight of the epoxy resin being 100 weight percent, the content of cresol novolac epoxy resin is 30 weight percent to 35 weight percent, the content of bisphenol A novolac epoxy resin is 30 weight percent to 35 weight percent, and the content of bisphenol A epoxy resin is 30 weight percent to 35 weight percent.

[0083] [Advantages of the Embodiment]

[0084] One of the advantages of the present invention is that the method for manufacturing the cured product and the metal foil layer substrate provided by the present invention can achieve the effect of preventing the floating of oily substances through the technical solutions of "the resin composition includes 40 to 60 parts by weight of the modified benzoxazine resin", "the modified benzoxazine resin has a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group", and "the proportion of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group is 10 weight percent to 20 weight percent".

[0085] Furthermore, the present invention adopts the technical solutions of "the modified benzoxazine resin is formed by reacting a DOPO group-containing compound, a diisocyanate compound, and a benzoxazine resin" or "the DOPO group-containing compound is grafted onto the main chain of the benzoxazine resin via a diisocyanate compound" to prepare the modified benzoxazine resin of the present invention, thereby achieving the effect of preventing the floating of oily substances.

[0086] Furthermore, the present invention adopts the technical solutions of "the phosphorus atom content in the modified benzoxazine resin is 1 weight percent to 2 weight percent" or "the phosphorus atom content in the DOPO group-containing compound is 12 weight percent to 20 weight percent" to achieve the effect of improving the heat resistance and flame retardancy of the cured product and the metal foil layer substrate.

[0087] The content disclosed above is only the preferred feasible embodiment of the present invention, and does not limit the protection scope of the claims of the present invention. Therefore, all equivalent technical changes made by using the content of the specification and drawings of the present invention are included in the protection scope of the claims of the present invention.

Claims

1. A method for manufacturing a cured product for a metal foil-clad substrate, characterized in that, The manufacturing method includes: Preparing a resin composition, the resin composition including: 20 to 40 parts by weight of an epoxy resin, 40 to 60 parts by weight of a modified benzoxazine resin, 2 to 10 parts by weight of a maleimide resin, and 25 to 50 parts by weight of a filler; wherein, the modified benzoxazine resin has a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group, and based on the total weight of the modified benzoxazine resin being 100 weight percentages, the proportion of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group is 10 weight percentages to 20 weight percentages; Coating the resin composition onto a metal substrate; Curing the resin composition at a temperature of 70°C to 200°C to form a semi-cured film; and Thermocompressing the semi-cured film to form a cured product; wherein, The synthesis steps of the modified benzoxazine resin include: Adding a DOPO group-containing compound to a benzoxazine resin and heating and dissolving at a temperature of 55°C to 95°C to form a reaction solution; and Adding a diisocyanate compound to the reaction solution and reacting at a temperature of 120°C to 140°C to generate the modified benzoxazine resin.

2. The manufacturing method according to claim 1, characterized in that, The DOPO group-containing compound is grafted onto the main chain of the benzoxazine resin via the diisocyanate compound.

3. The manufacturing method according to claim 1, characterized in that, The phosphorus atom content in the DOPO group-containing compound is 12 weight percentages to 20 weight percentages.

4. The manufacturing method according to claim 1, characterized in that, The DOPO group-containing compound is as shown in formula (I):

5. The manufacturing method according to claim 1, wherein The diisocyanate compound is selected from the group consisting of: isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, hexamethylene diisocyanate, and combinations thereof.

6. The manufacturing method according to claim 1, characterized in that, The benzoxazine resin is a bisphenol A-type modified benzoxazine resin, a bisphenol F-type modified benzoxazine resin, a diamine-type modified benzoxazine resin, or a combination thereof.

7. The manufacturing method according to claim 1, characterized in that, The phosphorus atom content in the modified benzoxazine resin is 1 weight percentage to 2 weight percentages.

8. A method for manufacturing a metal foil layer substrate, characterized in that, The manufacturing method includes: Preparing a resin composition, the resin composition including: 20 to 40 parts by weight of an epoxy resin, 40 to 60 parts by weight of a modified benzoxazine resin, 2 to 10 parts by weight of a maleimide resin, and 25 to 50 parts by weight of a filler; wherein, the modified benzoxazine resin has a 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group, and based on the total weight of the modified benzoxazine resin being 100 weight percentages, the proportion of the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide group is 10 weight percentages to 20 weight percentages; Coating the resin composition onto a metal substrate; Curing the resin composition at a temperature of 70°C to 200°C to form a semi-cured film; and Providing a printed circuit board on the semi-cured film and obtaining a metal foil layer substrate after thermocompression; wherein, The synthesis steps of the modified benzoxazine resin include: Add a DOPO-based compound to a benzoxazine resin and heat and dissolve it at a temperature of 55°C to 95°C to form a reactant solution; and Add a diisocyanate compound to the reactant solution and react it at a temperature of 120°C to 140°C to produce a modified benzoxazine resin.

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