A processing technology for flame-retardant and high-temperature resistant circuit boards

Abstract

This invention relates to the field of printed circuit boards, specifically to a processing technology for flame-retardant and high-temperature resistant printed circuit boards. The invention discloses a processing technology for flame-retardant and high-temperature resistant printed circuit boards. The invention involves reacting 3,4,5-trihydroxybenzoic acid with 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane to obtain a polysiloxane, which is then reacted with a mixed reagent of phosphorus pentoxide and phosphoric acid to prepare a phosphate ester flame-retardant material with good compatibility with epoxy resin. Because the main chain structure of the polysiloxane is Si-O-Si, it has good stability, and blending it can effectively improve the heat resistance of the epoxy resin substrate. Compared with inorganic flame retardants, adding the flame retardant prepared by this invention can compensate for the mechanical strength of the cured epoxy resin material; compared with halogenated flame retardants, this invention can avoid the generation of toxic gases and smoke during combustion.

Description

Technical Field

[0001] This invention relates to the field of circuit board technology, specifically to a processing technology for flame-retardant and high-temperature resistant circuit boards. Background Technology

[0002] With the advent of the Third Industrial Revolution, the electronics, information, and communication technology industries developed rapidly, giving rise to printed circuit boards (PCBs). The concept of printed circuit boards was first proposed by the British in 1936, and in recent decades it has gradually become one of the most important components of the electronics industry, involving the intersection, penetration, and mutual promotion of multiple disciplines, and developing in tandem with the entire field of electronic communication technology.

[0003] The 5G era places new demands on printed circuit boards (PCBs) for high-frequency electronic information transmission. PCBs typically use insulating resin as their substrate, and the choice of substrate plays a crucial role in the performance and quality of the printed circuit board. As a high-molecular polymer, epoxy resin exhibits numerous excellent properties after curing, such as strong metal adhesion and high chemical corrosion resistance, making it widely used in PCB manufacturing. However, the highly flammable nature of epoxy resin significantly limits its application in microelectronics. Conventional modification methods mainly compensate for the shortcomings of epoxy resin by adding high-temperature resistant, flame-retardant inorganic fillers. However, due to the uneven dispersion of inorganic materials in epoxy resin, phase separation is prone to occur, which not only reduces the mechanical properties and glass transition temperature of the epoxy resin but also causes the cured epoxy resin substrate to become brittle, affecting the quality of the PCB. Therefore, it is essential to develop a flame-retardant, high-temperature resistant PCB. Summary of the Invention

[0004] The purpose of this invention is to provide a processing technology for flame-retardant and high-temperature resistant circuit boards to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] Step 1: Disperse 1-2 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir until homogeneous, add 2.4-4.8 mol of potassium carbonate, heat to 75-85℃, continue stirring for 15-30 min, then add 1-2 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 48-60 h to obtain mixture A;

[0007] Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 3-4, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 3-4 times to obtain hyperbranched polysiloxane.

[0008] Step 3: Mix phosphoric acid and phosphorus pentoxide in a certain proportion to obtain a phosphorylating agent; heat the hyperbranched polysiloxane to 45°C, and continuously add the phosphorylating agent until the pH of the system is 4-5 to obtain mixture B; add p-toluenesulfonic acid, react at 75-85°C for 4-5 hours, and then hydrolyze for 2-3 hours; add sodium hydroxide solution to adjust the pH to neutral, and add deionized water to adjust the solid content to obtain a flame retardant;

[0009] Step 4: Heat the bisphenol A epoxy resin to 45-50°C, add curing agent, methyl ether, accelerator, and flame retardant, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the copper foil onto the resin solution, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, the circuit board is obtained.

[0010] Furthermore, in step 1, the molar ratio of 3,4,5-trihydroxybenzoic acid, potassium carbonate, and 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane is (1-2):(2.4-4.8):(1-2).

[0011] Furthermore, in step 3, the molar ratio of phosphoric acid to phosphoric acid pentoxide in the phosphorylating agent is (2-3):1.

[0012] Furthermore, in step 3, the amount of p-toluenesulfonic acid used is 0.8 to 1% of mixture B by weight.

[0013] Furthermore, in step 3, the reaction temperature is 75–85°C, the reaction time is 4–5 h, and the hydrolysis time is 2–3 h.

[0014] Furthermore, in step 3, the solid content of the flame retardant is 30-35%.

[0015] Furthermore, in step 4, by weight, there are 100-115 parts of bisphenol A epoxy resin, 16-20 parts of curing agent, 10-15 parts of methyl ether, 5-8 parts of accelerator, and 15-20 parts of flame retardant.

[0016] Furthermore, in step 4, the curing agent is any one of ethylenediamine, hexamethylenediamine, diethylenetriamine, maleic anhydride, tetraethylenepentamine, phthalic anhydride, and methylhexahydrophthalic anhydride.

[0017] Furthermore, in step 4, the accelerator is any one of N,N-dimethylbenzylamine, N,N-dimethylurea, dimethylimidazole, and 2-ethyl-4-methylimidazole.

[0018] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention uses a hyperbranching reaction to react 3,4,5-trihydroxybenzoic acid with three hydroxyl groups with 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane to obtain polysiloxane. Then, through a phosphorylation agent and reaction with phenolic hydroxyl groups, a phosphate ester flame retardant material with good compatibility with epoxy resin is prepared. In the polysiloxane, the main chain structure is Si-O-Si, which has good stability and can improve the heat resistance of the epoxy resin substrate. Compared with inorganic flame retardants, polysiloxane has good compatibility with epoxy resin, and blending can compensate for the mechanical strength of the cured epoxy resin material. Compared with halogenated flame retardants, this invention can reduce the generation of toxic gases and smoke during combustion. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The main materials and their sources in the following examples are as follows: 3,4,5-trihydroxybenzoic acid (CAS No.: 149-91-7) from Alpha; N,N-dimethylformamide (CAS No.: 68-12-2) from Sinopharm; potassium carbonate (CAS No.: 584-08-7) from Aladdin; 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane (CAS No.: 2362-10-9) from Delta Bio; hydrochloric acid (CAS No.: 7647-01-0) from Aladdin; tetrahydrofuran (CAS No.: 109-99-9) from Maclean's; phosphoric acid (CAS No.: 7664-38- 2) From Aladdin; Phosphorus pentoxide (CAS No.: 1314-56-3) from Sichuan Phosphorus Chemical; p-Toluenesulfonic acid (CAS No.: 104-15-4) from Maclean; Sodium hydroxide (CAS No.: 1310-73-2) from Aladdin; Bisphenol A epoxy resin (CAS No.: 25085-99-8) from Xinchen Synthetic Materials, item number 6101-E44; Maleic anhydride (CAS No.: 108-31-6) from Qiboxiang Tengda Chemical; Dimethyl ether (CAS No.: 115-10-6) from Tianjian Chemical; 2-Ethyl-4-methylimidazolium (CAS No.: 931-36-2) from Aladdin.

[0021] Example 1:

[0022] Step 1: Disperse 1 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir well, add 2.4 mol of potassium carbonate, heat to 75℃, continue stirring for 15 min, then add 1 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 48 h to obtain mixture A;

[0023] Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 3, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 3 times to obtain hyperbranched polysiloxane.

[0024] Step 3: Mix 2 mol of phosphoric acid and 1 mol of phosphorus pentoxide to obtain a phosphorylating agent; heat the hyperbranched polysiloxane to 45°C, and continuously add the phosphorylating agent until the pH of the system is 4 to obtain mixture B; add 0.8% by weight of p-toluenesulfonic acid to mixture B, react at 75°C for 4 hours and then hydrolyze for 2 hours; adjust the pH to neutral using sodium hydroxide solution, add deionized water to adjust the solid content to 30%, and obtain the flame retardant;

[0025] Step 4: Heat 1 kg of bisphenol A epoxy resin to 50°C, add 0.16 kg of maleic anhydride, 0.1 kg of methyl ether, 0.05 kg of 2-ethyl-4-methylimidazole, and 0.15 kg of flame retardant, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the resin solution with copper foil, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, obtain the circuit board.

[0026] Example 2:

[0027] Step 1: Disperse 1.2 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir until homogeneous, add 2.9 mol of potassium carbonate, heat to 80℃, continue stirring for 20 min, then add 1.2 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 50 h to obtain mixture A;

[0028] Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 4, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 4 times to obtain hyperbranched polysiloxane.

[0029] Step 3: Mix 2.3 mol of phosphoric acid and 1 mol of phosphorus pentoxide to obtain a phosphorylating agent; heat the hyperbranched polysiloxane to 45°C, and continuously add the phosphorylating agent until the pH of the system is 4 to obtain mixture B; add 0.9% by weight of p-toluenesulfonic acid to mixture B, react at 80°C for 4.5 h and then hydrolyze for 2 h; adjust the pH to neutral using sodium hydroxide solution, add deionized water to adjust the solid content to 31%, and obtain the flame retardant;

[0030] Step 4: Heat 1.1 kg of bisphenol A epoxy resin to 55°C, add 0.17 kg of maleic anhydride, 0.12 kg of methyl ether, 0.06 kg of 2-ethyl-4-methylimidazole, and 0.17 kg of flame retardant, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the resin solution with copper foil, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, obtain the circuit board.

[0031] Example 3:

[0032] Step 1: Disperse 1.3 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir until homogeneous, add 3.1 mol of potassium carbonate, heat to 85℃, continue stirring for 20 min, then add 1.3 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 55 h to obtain mixture A;

[0033] Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 4, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 3 times to obtain hyperbranched polysiloxane.

[0034] Step 3: Mix 2.3 mol of phosphoric acid and 1 mol of phosphorus pentoxide to obtain a phosphorylating agent; heat the hyperbranched polysiloxane to 45°C, and continuously add the phosphorylating agent until the pH of the system is 4.5 to obtain mixture B; add 0.85% by weight of p-toluenesulfonic acid to mixture B, react at 75°C for 4 hours and then hydrolyze for 3 hours; adjust the pH to neutral using sodium hydroxide solution, and add deionized water to adjust the solid content to 32% to obtain a flame retardant;

[0035] Step 4: Heat 1.14 kg of bisphenol A epoxy resin to 58°C, add 0.175 kg of maleic anhydride, 0.11 kg of methyl ether, 0.075 kg of 2-ethyl-4-methylimidazole, and 0.18 kg of flame retardant, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the resin solution with copper foil, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, obtain the circuit board.

[0036] Example 4:

[0037] Step 1: Disperse 1.6 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir until homogeneous, add 3.8 mol of potassium carbonate, heat to 84℃, continue stirring for 30 min, then add 1.7 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 55 h to obtain mixture A;

[0038] Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 3, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 4 times to obtain hyperbranched polysiloxane.

[0039] Step 3: Mix 2.5 mol of phosphoric acid and 1 mol of phosphorus pentoxide to obtain a phosphorylating agent; heat the hyperbranched polysiloxane to 45°C, and continuously add the phosphorylating agent until the pH of the system is 4.5 to obtain mixture B; add 0.95% by weight of p-toluenesulfonic acid to mixture B, react at 80°C for 5 hours and then hydrolyze for 3 hours; adjust the pH to neutral using sodium hydroxide solution, and add deionized water to adjust the solid content to 33% to obtain a flame retardant;

[0040] Step 4: Heat 1.13 kg of bisphenol A epoxy resin to 50°C, add 0.185 kg of maleic anhydride, 0.135 kg of methyl ether, 0.072 kg of 2-ethyl-4-methylimidazole, and 0.165 kg of flame retardant, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the resin solution with copper foil, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, obtain the circuit board.

[0041] Example 5:

[0042] Step 1: Disperse 1.8 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir until homogeneous, add 4.4 mol of potassium carbonate, heat to 75℃, continue stirring for 25 min, then add 1.8 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 58 h to obtain mixture A;

[0043] Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 3, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 4 times to obtain hyperbranched polysiloxane.

[0044] Step 3: Mix 2.7 mol of phosphoric acid and 1 mol of phosphorus pentoxide to obtain a phosphorylating agent; heat the hyperbranched polysiloxane to 45°C, and continuously add the phosphorylating agent until the pH of the system is 4 to obtain mixture B; add 1% by weight of p-toluenesulfonic acid to mixture B, react at 80°C for 5 hours and then hydrolyze for 2 hours; adjust the pH to neutral using sodium hydroxide solution, and add deionized water to adjust the solid content to 34% to obtain a flame retardant;

[0045] Step 4: Heat 1.14 kg of bisphenol A epoxy resin to 56°C, add 0.195 kg of maleic anhydride, 0.13 kg of methyl ether, 0.07 kg of 2-ethyl-4-methylimidazole, and 0.19 kg of flame retardant, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the resin solution with copper foil, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, obtain the circuit board.

[0046] Example 6:

[0047] Step 1: Disperse 2 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir evenly, add 4.8 mol of potassium carbonate, heat to 85℃, continue stirring for 30 min, then add 2 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 60 h to obtain mixture A;

[0048] Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 3, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 4 times to obtain hyperbranched polysiloxane.

[0049] Step 3: Mix 3 mol of phosphoric acid and 1 mol of phosphorus pentoxide to obtain a phosphorylating agent; heat the hyperbranched polysiloxane to 45°C, and continuously add the phosphorylating agent until the pH of the system is 5 to obtain mixture B; add 1% by weight of p-toluenesulfonic acid to mixture B, react at 85°C for 5 hours and then hydrolyze for 3 hours; adjust the pH to neutral using sodium hydroxide solution, and add deionized water to adjust the solid content to 35% to obtain a flame retardant;

[0050] Step 4: Heat 1.15 kg of bisphenol A epoxy resin to 60°C, add 0.2 kg of maleic anhydride, 0.15 kg of methyl ether, 0.08 kg of 2-ethyl-4-methylimidazole, and 0.2 kg of flame retardant, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the resin solution with copper foil, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, obtain the circuit board.

[0051] Comparative Example 1:

[0052] 1 kg of bisphenol A epoxy resin is heated to 50°C, and 0.16 kg of maleic anhydride, 0.1 kg of methyl ether, and 0.05 kg of 2-ethyl-4-methylimidazole are added and mixed evenly to obtain a resin solution. The resin solution is coated onto a glass fiber cloth, and after semi-curing, copper foil is placed on the resin solution. The mixture is then hot-pressed and cured to obtain a high-temperature resistant epoxy resin-based copper-clad laminate. The circuit board is then obtained through grinding, circuit printing, etching, ink removal, and solder resist printing.

[0053] Comparative Example 2:

[0054] Step 1: Disperse 1.2 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir until homogeneous, add 2.9 mol of potassium carbonate, heat to 80℃, continue stirring for 20 min, then add 1.2 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 50 h to obtain mixture A;

[0055] Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 4, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 4 times to obtain hyperbranched polysiloxane.

[0056] Step 3: Heat 1.1 kg of bisphenol A epoxy resin to 55°C, add 0.17 kg of maleic anhydride, 0.12 kg of methyl ether, 0.06 kg of 2-ethyl-4-methylimidazole, and 0.17 kg of mixture A, and mix evenly to obtain a resin solution; coat the resin solution onto a fiberglass cloth, and after semi-curing, cover the copper foil onto the resin solution, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, obtain the circuit board.

[0057] Comparative Example 3:

[0058] Step 1: Heat 1.14 kg of bisphenol A epoxy resin to 58°C, add 0.175 kg of maleic anhydride, 0.11 kg of methyl ether, 0.075 kg of 2-ethyl-4-methylimidazole, and 0.18 kg of magnesium hydroxide, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the resin solution with copper foil, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, the circuit board is obtained.

[0059] Comparative Example 4:

[0060] Step 1: Disperse 1.6 mol of 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir until homogeneous, add 3.8 mol of potassium carbonate, heat to 84℃, continue stirring for 30 min, then add 1.7 mol of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir and react for 55 h to obtain mixture A;

[0061] Step 2: Heat 1.13 kg of bisphenol A epoxy resin to 50°C, add 0.185 kg of maleic anhydride, 0.135 kg of methyl ether, 0.072 kg of 2-ethyl-4-methylimidazole, 0.18 kg of mixture A, and 0.165 kg of bis(hexachlorocyclopentadiene)cyclooctane and mix thoroughly to obtain a resin solution; coat the resin solution onto a fiberglass cloth, and after semi-curing, cover the resin solution with copper foil, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, obtain the circuit board.

[0062] experiment:

[0063] The following tests were performed on Examples 1-6 and Comparative Examples 1-4 respectively, and the experimental results are shown in the table below:

[0064] Flame retardancy: Tested using a CZF-5 horizontal and vertical flame tester according to the method specified in UL 94;

[0065] Thermal stability: Tested using a Pyris 6 thermogravimetric analyzer. Test conditions: Heating to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, with heat loss of 5% (T) recorded. 5％ The temperature at which it occurs;

[0066] Impact strength: Tested using a HIT-2492 composite pendulum impact testing machine in accordance with GB / T 1843-2008;

[0067] Fracture toughness: Tested using a Model 5940 universal testing machine in accordance with GB / T 2567-2008;

[0068]

[0069] Example 3 V-0 383 39.1 4.0 Example 4 V-0 392 41.5 4.2 Example 5 V-0 388 39.8 3.9 Example 6 V-0 390 41.6 4.0 Comparative Example 1 V-1 368 33.7 3.3 Comparative Example 2 V-1 387 40.1 4.0 Comparative Example 3 V-0 / 30.1 2.7 Comparative Example 4 V-0 / 38.6 3.8

[0070] Conclusion: This invention prepares polysiloxane by hyperbranching 3,4,5-trihydroxybenzoic acid with three hydroxyl groups and silane, and then reacts it with the hydroxyl groups through a phosphorylation agent to generate a phosphate ester flame retardant. Circuit boards prepared by blending the flame retardants prepared in Examples 1-6 with epoxy resin exhibit good high-temperature resistance and flame retardant effects. Comparative Example 1, using Example 1 as a reference, shows that the flame retardant prepared in this invention not only improves the thermal stability and high-temperature resistance of the circuit board, but also effectively improves its impact strength and fracture toughness. Comparative Example 2, using Example 2 as a reference, shows that the unphosphorylated polysiloxane has poor flame retardant effect, but because polysiloxane has a Si-O-Si main chain, it has strong stability, and blending it can improve the high-temperature resistance of the epoxy resin substrate; furthermore, due to the good compatibility between polysiloxane and epoxy resin, blending it can improve the mechanical properties of the circuit board. Referring to Example 3, the data from Comparative Example 3 show that using magnesium hydroxide as a flame retardant can improve flame retardant performance, but the mechanical strength will be affected. Referring to Example 4, Comparative Example 4 illustrates that using a halogenated flame retardant blended with polysiloxane can improve the flame retardant effect of the circuit board, but toxic gases and smoke will be produced during combustion.

[0071] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A processing technology for a flame-retardant and high-temperature resistant circuit board, characterized in that: Includes the following steps: Step 1: Disperse 3,4,5-trihydroxybenzoic acid in N,N-dimethylformamide, stir until homogeneous, add potassium carbonate, heat and add 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane, stir to react and obtain mixture A; Step 2: Centrifuge and concentrate mixture A, add hydrochloric acid solution to adjust the pH to 3-4, precipitate for 12 hours, filter and dissolve in tetrahydrofuran, repeat the operation 3-4 times to obtain hyperbranched polysiloxane. Step 3: Mix phosphoric acid and phosphorus pentoxide in a certain proportion to obtain a phosphorylating agent; heat the hyperbranched polysiloxane to 45°C, add the phosphorylating agent until the pH of the system is 4-5, to obtain mixture B; add p-toluenesulfonic acid, react and hydrolyze, adjust the pH to neutral, add deionized water to adjust the solid content to obtain a flame retardant. Step 4: Heat the bisphenol A epoxy resin, add curing agent, methyl ether, accelerator, and flame retardant, and mix evenly to obtain a resin solution; coat the resin solution onto fiberglass cloth, and after semi-curing, cover the copper foil onto the resin solution, hot press, and cure to obtain a high-temperature resistant epoxy resin-based copper-clad laminate; then, through grinding, circuit printing, etching, ink removal, and solder resist printing, the circuit board is obtained. In step 1, the molar ratio of 3,4,5-trihydroxybenzoic acid, potassium carbonate, and 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane is (1-2):(2.4-4.8):(1-2). In step 3, the molar ratio of phosphoric acid to phosphoric acid pentoxide in the phosphorylating agent is (2-3):1; and the amount of p-toluenesulfonic acid used is 0.8-1% of mixture B by weight.

2. The processing technology of a flame-retardant and high-temperature resistant circuit board according to claim 1, characterized in that: In step 3, the reaction temperature is 75–85°C; the reaction time is 4–5 h; the hydrolysis time is 2–3 h; and the solid content of the flame retardant is 30–35%.

3. The processing technology of a flame-retardant and high-temperature resistant circuit board according to claim 1, characterized in that: In step 4, by weight, there are 100-115 parts of bisphenol A epoxy resin, 16-20 parts of curing agent, 10-15 parts of methyl ether, 5-8 parts of accelerator, and 15-20 parts of flame retardant.

4. The processing technology of a flame-retardant and high-temperature resistant circuit board according to claim 1, characterized in that: In step 4, the curing agent is any one of ethylenediamine, hexamethylenediamine, diethylenetriamine, maleic anhydride, tetraethylenepentamine, phthalic anhydride, and methylhexahydrophthalic anhydride.

5. The processing technology of a flame-retardant and high-temperature resistant circuit board according to claim 1, characterized in that: In step 4, the accelerator is any one of N,N-dimethylbenzylamine, N,N-dimethylurea, dimethylimidazole, and 2-ethyl-4-methylimidazole.

6. A circuit board prepared by the processing technology of a flame-retardant and high-temperature resistant circuit board according to any one of claims 1 to 5.

Images