Copper clad laminate and preparation method thereof

Abstract

The present application relates to the technical field of copper clad laminate production, and in particular to a copper clad laminate and a preparation method thereof. A preparation method for a copper clad laminate comprises the following steps: preparing a copper foil layer, a surface prepreg, a core prepreg, a surface prepreg, and a copper foil layer by sequentially stacking the layers through high-temperature pressing; using a low-halogen epoxy resin composition with a low solid content of modified fillers in the core prepreg to improve the peel strength and bending strength of the copper clad laminate; using a low-halogen epoxy resin composition with a high solid content of modified fillers in the surface prepreg to improve the heat resistance, flame retardancy, arc resistance, and leakage resistance of the copper clad laminate; using a low-halogen epoxy resin, a surface prepreg, and a core prepreg in combination, the prepared copper clad laminate has excellent heat resistance, flame retardancy, arc resistance, and leakage tracking resistance, as well as excellent bending strength and peel strength, and is environmentally friendly and meets environmental protection requirements.

Description

Technical Field

[0001] The present application relates to the technical field of copper clad laminate production, and in particular to a copper clad laminate and a preparation method thereof. Background Art

[0002] Copper-clad laminate, also known as base material, is a sheet material made by impregnating a reinforcing material with an adhesive resin, coating one or both sides with copper foil, and then heat-pressing. It is also called copper-clad laminate and is the fundamental material for PCBs. When used in multi-layer boards, it is also called core. Copper-clad laminate consists of three main components: base material, copper foil, and adhesive. It is primarily used in the manufacture of printed circuit boards and plays a vital role in the electronics industry, including televisions, radios, computers, and mobile communications.

[0003] During the use of copper-clad laminates, when there is moisture and dirt on the surface of the copper-clad laminate and the electric field is large enough, leakage current will be generated on the surface. Under the action of Joule heat of the current, the water is evaporated, and a gap (called a dry zone) is formed as the liquid film on the surface of the material separates. At the moment the dry zone is formed, the field strength between the liquid films reaches the discharge field strength, causing discharge. The heat generated by the discharge causes local carbonization of the material surface. Due to the high conductivity of the carbonized product, the electric field density here is concentrated in the carbonized part, causing repeated discharge, generating more carbides around it, forming a carbonized conductive path, and extending toward the electrode, eventually leading to a short circuit.

[0004] With the advancement of lead-free electronic products, the use of medium- and high-Tg copper-clad laminates is becoming increasingly widespread. However, due to the reliance on halogen-based flame-retardant copper-clad laminates, halogen elements are easily ionized in humid environments, increasing water absorption and reducing moisture resistance. This results in poor resistance to electrical tracking damage, which ultimately limits the use of copper-clad laminates. This is particularly evident in high-density PCB applications where performance deficiencies have been demonstrated. Therefore, the development of copper-clad laminates with high tracking resistance has a positive impact on the development of environmentally friendly electronic products.

[0005] In order to improve the tracking resistance and high temperature resistance of existing copper clad laminates, inorganic fillers are generally used to improve the adhesive resin to enhance the heat resistance, flame retardancy, arc resistance, and leakage resistance of the adhesive resin. However, there are generally interface problems between the inorganic fillers and the adhesive resin, which will lead to a decrease in the bending strength and peel strength of the copper clad laminate. Summary of the Invention

[0006] The present application solves the problem that existing copper clad laminates are difficult to have good heat resistance, flame retardancy, arc resistance, leakage resistance, bending strength and peel strength at the same time. The present application provides a copper clad laminate and a preparation method thereof.

[0007] In a first aspect, the present application provides a method for preparing a copper clad laminate.

[0008] A method for preparing a copper clad laminate comprises the following steps:

[0009] S1. Preparation of a low-halogen epoxy resin composition: 25-115 parts by mass of a modified filler, 60-80 parts by mass of a low-halogen epoxy resin, and 25-35 parts by mass of a curing agent are stirred and mixed to prepare a low-halogen epoxy resin composition having a modified filler solid content of 20-30% and a low-halogen epoxy resin composition having a modified filler solid content of 30-50% as required; the modified filler is prepared by surface-modifying an inorganic filler with a dispersant;

[0010] S2. Preparation of surface prepreg and core prepreg: coating the reinforcing material with a low-halogen epoxy resin composition having a solid content of 20-30% of a modified filler to obtain a core prepreg; coating the reinforcing material with a low-halogen epoxy resin composition having a solid content of 30-50% of a modified filler, and drying to obtain a surface prepreg;

[0011] S3. Preparation of copper clad laminate: copper foil layer, surface prepreg, core prepreg, surface prepreg and copper foil layer are stacked in sequence and pressed at high temperature to prepare copper clad laminate.

[0012] By adopting the above technical solution, inorganic fillers are used to improve the heat resistance, flame retardancy, arc resistance and leakage resistance of the low-halogen epoxy resin composition, and dispersants are used to improve the surface of the inorganic filler to prepare a modified filler, thereby improving the problem of poor interface compatibility between the modified filler and the epoxy resin. As a result, the copper clad laminate using the low-halogen epoxy resin composition not only has excellent heat resistance, flame retardancy, arc resistance and leakage resistance, but also has excellent bending strength and peel strength.

[0013] Due to the interface problem between inorganic fillers and epoxy resin, too much inorganic filler content may lead to reduced adhesion and bending strength of the epoxy resin composition, causing the copper clad laminate to crack easily.

[0014] In the present application, a gradient change in the inorganic filler content of the low-halogen epoxy resin composition in the copper clad laminate is further set. A low-halogen epoxy resin composition with a low solid content of modified fillers is used in the core layer semi-cured sheet, which is beneficial to improving the peel strength and bending strength of the copper clad laminate; a low-halogen epoxy resin composition with a high solid content of modified fillers is used in the surface layer semi-cured sheet, which is beneficial to improving the heat resistance, flame retardancy, arc resistance and leakage resistance of the copper clad laminate; the low-halogen epoxy resin, the surface layer semi-cured sheet and the core layer semi-cured sheet are used in combination, so that the prepared copper clad laminate has excellent heat resistance, flame retardancy, arc resistance and leakage tracking resistance, as well as excellent bending strength and peel strength, and is environmentally friendly and meets environmental protection requirements.

[0015] Preferably, the preparation process of the modified filler is as follows:

[0016] A polyol and boric acid are mixed in proportion, stirred and reacted at a temperature of 100-300°C for 3-8 hours to obtain a borate ester; maleic anhydride is then added, and stirred and reacted at 100-300°C for 3-8 hours to prepare a borate ester dispersant; the mass ratio of the polyol, boric acid and maleic anhydride is (1-2):(0.5-1):1;

[0017] After uniformly mixing a borate dispersant, ground filler and water in a mass ratio of (7-10):4:100, stirring and modifying for 3-5 hours at a temperature of 60-80°C to prepare a suspension, then allowing to stand, filter pressing and drying to prepare a modified filler.

[0018] By adopting the above technical scheme, a borate dispersant and a modified filler are prepared. The molecular chain of the borate dispersant contains hydroxyl and carboxyl groups, and the borate dispersant has good dispersing performance on the filler; the borate dispersant contains boron element, and the boron element has good compatibility with the active hydrogen in other raw materials, thereby improving the adhesion of the low-halogen epoxy resin composition using the modified filler and the interaction force between the modified filler and the low-halogen epoxy resin; the molecular chain of the borate dispersant of the modified filler contains hydroxyl groups, carboxyl groups, boron elements and carbon-carbon double bonds, which work together, so that the modified filler has good dispersing performance in the low-halogen epoxy resin, mutual synergy with the low-halogen epoxy resin and high adhesion performance, thereby making the prepared copper clad laminate have excellent thermal stress, relative tracking index, peel strength and bending strength.

[0019] Preferably, the raw materials of the modified filler further include vinyltributylon oxime-based silane and hydrogen-containing silicone oil; the mass ratio of the vinyltributylon oxime, hydrogen-containing silicone oil-based silane and filler is (0.2-0.4):0.3:4.

[0020] By adopting the above technical solution, vinyl tributylanoxime silane and hydrogen-containing silicone oil are used in the raw materials of the modified filler, and the borate dispersant contains a carbon-carbon double bond that reacts with the double-terminal hydrogen-containing silicone oil. The double-terminal hydrogen-containing silicone oil can react with the vinyl tributylanoxime silane, further improving the dispersibility, toughness and adhesion of the low-halogen epoxy resin composition; thereby, the prepared copper clad laminate has excellent thermal stress, relative tracking index, peel strength and bending strength.

[0021] Preferably, the hydrogen-containing silicone oil is a double-ended hydrogen-containing silicone oil with a hydrogen content of 0.016-0.08%.

[0022] By adopting the above technical solution, the higher the hydrogen content of the hydrogen-containing silicone oil, the less favorable it is for the toughness of the low-halogen epoxy resin composition; the hydrogen-containing silicone oil is preferably a double-ended hydrogen-containing silicone oil with a hydrogen content of 0.016-0.08%, which further improves the thermal stress, peel strength and bending strength of the copper clad laminate.

[0023] Preferably, the polyol is one of pentaerythritol, trimethylolethane, xylitol and sorbitol.

[0024] By adopting the above technical solution, polyols containing more hydroxyl groups are preferred, which is beneficial to improving the dispersion performance of the modified filler, thereby improving the prepared copper clad laminate and having excellent thermal stress, relative tracking index, peel strength and bending strength.

[0025] Preferably, the inorganic filler is at least two of aluminum hydroxide, barium sulfate, titanium dioxide, boron nitride, graphene oxide, aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, and silicon carbide;

[0026] By adopting the above technical solution and optimizing the filler, the thermal stress, flame retardancy, relative tracking index, peel strength and bending strength of the prepared copper clad laminate are improved.

[0027] Preferably, the inorganic filler is a composition of aluminum hydroxide, barium sulfate and boron nitride in a mass ratio of 1:1:(0.2-0.4).

[0028] By adopting the above technical solution, the filler adopts a composition of aluminum hydroxide, barium sulfate and boron nitride in a mass ratio of 1:1:(0.8-1.4). Aluminum hydroxide, barium sulfate and boron nitride have a good synergistic effect, which improves the thermal stress, peel strength and bending strength of the prepared copper clad laminate.

[0029] Preferably, the curing agent is a composition of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone in a mass ratio of (2-4):1.

[0030] By adopting the above technical solution, the curing agent uses dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone, which not only allows the low-halogen epoxy resin to be cured at high temperature; but also 4,4-diaminodiphenyl sulfone improves the high-temperature resistance of the low-halogen epoxy resin composition, dodecenylsuccinic anhydride can improve the flexibility of the low-halogen epoxy resin composition, and the combination of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone further improves the thermal stress, peel strength and bending strength of the copper clad laminate prepared using the low-halogen epoxy resin composition.

[0031] Preferably, in the preparation of the surface prepreg and the core prepreg, the drying temperature is 150-170°C and the baking time is 5-8 minutes; in the preparation of the copper clad laminate, the pressing pressure is 30-40 kg / cm2， The pressing temperature is 200-250°C and the pressing time is 3-5h.

[0032] By adopting the above technical solution, a reaction occurs between the low-halogen epoxy resin, the curing agent, and the modified filler at high temperature, so that the prepared copper clad laminate becomes a whole and has high thermal stress, peel strength, and bending strength.

[0033] On the other hand, the present application provides a copper clad laminate.

[0034] A copper clad laminate is prepared using the method for preparing the copper clad laminate in the present application. The copper clad laminate has a flame retardancy of V0 level (UL-94), a thermal stress of ≥90s, a PLC:0 level (600V), a glass transition temperature Tg ≥150°C (DSC), excellent electrical tracking resistance, and low halogen environmental performance, and complies with the standards for microelectronics and multifunctional electronic products in IPC-4101D.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. A method for preparing a copper clad laminate, comprising: performing high-temperature pressing on a copper foil layer, a surface prepreg, a core layer prepreg, a surface prepreg, and a copper foil layer stacked in sequence; using a low-halogen epoxy resin composition having a low solid content of a modified filler in the core layer prepreg, thereby improving the peel strength and bending strength of the copper clad laminate; using a low-halogen epoxy resin composition having a high solid content of a modified filler in the surface layer prepreg, thereby improving the heat resistance, flame retardancy, arc resistance, and leakage resistance of the copper clad laminate; using the low-halogen epoxy resin, the surface layer prepreg, and the core layer prepreg in combination, the prepared copper clad laminate has excellent heat resistance, flame retardancy, arc resistance, and tracking resistance, as well as excellent bending strength and peel strength, and is environmentally friendly and meets environmental protection requirements.

[0037] 2. Among the raw materials of the modified filler, vinyl trisbutyl ketoxime silane with good adhesion and hydrogen-containing silicone oil with good compliance are used in combination. The borate dispersant contains a carbon-carbon double bond that reacts with the double-ended hydrogen-containing silicone oil. The double-ended hydrogen-containing silicone oil can react with vinyl trisbutyl ketoxime silane, further improving the dispersibility, toughness and adhesion of the low-halogen epoxy resin composition; thereby, the prepared copper clad laminate has excellent thermal stress, relative tracking index, peel strength and bending strength.

[0038] 3. The curing agent adopts a composition of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone in a mass ratio of (2-4):1. 4,4-diaminodiphenyl sulfone improves the high temperature resistance of the low-halogen epoxy resin composition, dodecenylsuccinic anhydride improves the flexibility of the low-halogen epoxy resin composition, and the combination of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone further improves the thermal stress, peel strength and bending strength of the copper clad laminate prepared using the low-halogen epoxy resin composition. DETAILED DESCRIPTION

[0039] raw material

[0040] Low-halogen epoxy resin (bisphenol F epoxy, epoxy equivalent 170 g / eq., viscosity: 4000 mPa.s@25°C, total chlorine: 300 ppm), nano-graphene oxide (thickness 0.6-1.2 nm, diameter 0.8-2 μm, purity 99%), E-type glass fiber cloth (dielectric constant approximately 6.6 (1 MHz), dielectric loss constant 0.001 (1 MHz)), barium sulfate (average particle size D50: 1.3 microns, active ingredient content 98%), aluminum hydroxide (average particle size 2 μm, active ingredient content 99%), boron nitride (boron content ≥99.9%, average particle size 5 μm), titanium dioxide (average particle size 5 μm, active ingredient content 99%).

[0041] Preparation examples of intermediates

[0042] Preparation Example 1, a preparation process for a modified filler, using raw materials as shown in Table 1, the specific steps are as follows:

[0043] Preparation of borate dispersant: Polyol (pentaerythritol) and boric acid were added to a reactor and reacted at 300°C and 800 rpm for 3 hours to obtain the borate. Maleic anhydride was then added and stirred at 300°C for 3 hours to prepare the borate dispersant. The mass ratio of polyol, boric acid, and maleic anhydride was 2:1:1.

[0044] Grinding the filler: Place the filler (a composition of barium sulfate and aluminum hydroxide in a mass ratio of 1:1) in a grinder and grind it at 1000 r / min for 5 minutes.

[0045] Preparation of modified filler: Vinyl trisbutyl ketoxime silane, double-end hydrogenated silicone oil (hydrogen content 0.08%), borate dispersant, ground filler and water in a mass ratio of 0.4:0.3:10:4:100 are placed in a reactor, and stirred and modified for 3 hours at a temperature of 80°C and a speed of 1000 r / min to prepare a suspension. The suspension is then drained, allowed to stand, filtered and dried to prepare a modified filler.

[0046] Preparation Example 2, a preparation process for a modified filler, differs from Preparation Example 1 in that the types of raw materials used, the weight of raw materials used, and the preparation process parameter settings are different, as follows:

[0047] Preparation of borate dispersant: Polyol (pentaerythritol) and boric acid were added to a reactor and reacted at 200°C and 600 rpm for 5 hours to produce the borate. Maleic anhydride was then added and stirred at 200°C for 5 hours to produce the borate dispersant. The mass ratio of polyol, boric acid, and maleic anhydride was 1.5:0.8:1.

[0048] Grinding the filler: Place the filler (a composition of barium sulfate and titanium dioxide in a mass ratio of 1:1) in a grinder and grind it at 900 r / min for 5 minutes.

[0049] Preparation of modified filler: Vinyl trisbutyl ketoxime silane, double-end hydrogenated silicone oil (hydrogen content 0.03%), borate dispersant, ground filler and water in a mass ratio of 0.3:0.3:8:4:100 are placed in a reactor, stirred and modified for 4 hours at a temperature of 70°C and a speed of 900 r / min to prepare a suspension, and then the suspension is drained, allowed to stand, filtered and dried to prepare the modified filler.

[0050] Preparation Example 3, a preparation process for a modified filler, differs from Preparation Example 1 in that the types of raw materials used, the weight of raw materials used, and the preparation process parameter settings are different, as follows:

[0051] Preparation of borate dispersant: Polyol (sorbitol) and boric acid were added to a reactor and reacted at 100°C and 500 rpm for 8 hours to obtain the borate. Maleic anhydride was then added and stirred at 100°C for 8 hours to obtain the borate dispersant. The mass ratio of polyol, boric acid, and maleic anhydride was 1:0.5:1.

[0052] Grinding the filler: placing the filler (a composition of graphene oxide and titanium dioxide in a mass ratio of 1:0.5) in a grinder and grinding it at 800 r / min for 5 min.

[0053] Preparation of modified filler: Vinyl trisbutyl ketoxime silane, double-end hydrogenated silicone oil (hydrogen content 0.16%), borate dispersant, ground filler and water in a mass ratio of 0.2:0.3:7:4:100 are placed in a reactor, and stirred and modified for 5 hours at a temperature of 60°C and a speed of 800 r / min to prepare a suspension. The suspension is then drained, allowed to stand, filtered and dried to prepare a modified filler.

[0054] Preparation Example 4 is a preparation process for a modified filler. The difference from Preparation Example 1 is that phosphoric acid is used in equal amounts to replace boric acid, succinic anhydride is used in equal amounts to replace maleic anhydride, and 1,4-butanediol is used as the polyol.

[0055] Preparation Example 5 is a preparation process for a modified filler, which differs from Preparation Example 1 in that maleic anhydride is not used.

[0056] Preparation Example 6, a preparation process for a modified filler, differs from Preparation Example 1 in that the mass ratio of polyol, boric acid and maleic anhydride is 2.3:0.3:0.8.

[0057] Preparation Example 7 is a preparation process for a modified filler. The difference from Preparation Example 1 is that an equal amount of sodium pyrophosphate is used to replace the borate dispersant.

[0058] Preparation Example 8, a preparation process for a modified filler, differs from Preparation Example 1 in that the filler uses a composition of aluminum hydroxide, barium sulfate, and boron nitride in a mass ratio of 1:1:0.2.

[0059] Preparation Example 9 is a preparation process for a modified filler. The difference from Preparation Example 1 is that the filler uses a composition of aluminum hydroxide, barium sulfate and boron nitride in a mass ratio of 1:1:0.4.

[0060] Preparation Example 10 is a preparation process for a modified filler. The difference from Preparation Example 1 is that the filler uses a composition of aluminum hydroxide, barium sulfate and boron nitride in a mass ratio of 1:1:0.8.

[0061] Preparation Example 11, a preparation process for a modified filler, which differs from Preparation Example 1 in that the filler uses a composition of aluminum hydroxide, barium sulfate and boron nitride in a mass ratio of 1:1:0.1

[0062] Preparation Example 12, a preparation process for a modified filler, differs from Preparation Example 1 in that the filler uses a composition of aluminum hydroxide, barium sulfate and graphene oxide in a mass ratio of 1:1:0.2.

[0063] Preparation Example 13, a preparation process for a modified filler, differs from Preparation Example 1 in that the filler uses a composition of titanium dioxide and barium sulfate in a mass ratio of 1:1.

[0064] Preparation Example 14, a preparation process for a modified filler, differs from Preparation Example 1 in that end-side hydrogenated silicone oil with a hydrogen content of 0.1% is used; and the mass ratio of vinyl trisbutyl ketone oxime, hydrogenated silicone oil-based silane, and filler is 0.1:0.3:1.5.

[0065] Preparation Example 15 is a preparation process for a modified filler, which differs from Preparation Example 1 in that hydrogenated silicone oil is not used.

[0066] Preparation Example 16 is a preparation process for a modified filler, which differs from Preparation Example 1 in that vinyltributylonoximesilane is not used.

[0067] Preparation Example 17 is a preparation process for a modified filler. The difference from Preparation Example 1 is that hydrogenated silicone oil and vinyltributylanoximesilane are not used.

[0068] Example

[0069] Example 1, a method for preparing a copper clad laminate, using raw materials as shown in Table 1, specifically comprising the following preparation steps:

[0070] Step S1: Preparation of low halogen epoxy resin composition

[0071] The modified filler, low-halogen epoxy resin and curing agent were added to a stirring kettle, and stirred and mixed for 10 hours at a rotation speed of 500r±50 / min to prepare a low-halogen epoxy resin composition for the surface prepreg and the core prepreg as required.

[0072] The solid content of the low-halogen epoxy resin composition used for the surface layer prepreg is set to 50%; the solid content of the low-halogen epoxy resin composition used for the core layer prepreg is set to 30%.

[0073] Step S2: Preparation of surface prepreg and core prepreg

[0074] A low-halogen epoxy resin composition was coated on an E-type glass fiber cloth using a vertical glue coating machine to prepare a surface prepreg and a core prepreg, with the glue content being controlled at 20±3 g / m2.

[0075] The working parameters of the vertical glue coating machine are: oven temperature is 170℃ and baking time is 8min.

[0076] Step S3: Preparation of copper clad laminate:

[0077] The copper foil layer (215g / ㎡), surface prepreg, core prepreg, surface prepreg and copper foil layer stacked in sequence are placed in a vacuum press for pressing. The working parameters of the vacuum press are: pressing pressure of 40kg / cm 2 The pressing temperature is 200℃ and the pressing time is 5h to prepare a copper clad laminate.

[0078] Examples 2 to 3 are methods for preparing copper clad laminates. The difference from Example 1 is that the types of raw materials, weights of raw materials, and preparation process parameter settings used are different, as shown in Table 1.

[0079] Table 1. Raw material types, raw material weights, and preparation process parameter settings used in the preparation methods of copper clad laminates of Examples 1 to 3

[0080]

[0081]

[0082] Examples 4 to 17 are methods for preparing copper-clad laminates, which differ from Example 1 in that the modified fillers are prepared by sequentially adopting the preparation processes of the modified fillers of Preparation Examples 4 to 17.

[0083] Example 18, a method for preparing a copper clad laminate, differs from Example 1 in that the curing agent is a composition of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone in a mass ratio of 2:1.

[0084] Example 19, a method for preparing a copper clad laminate, differs from Example 1 in that the curing agent is a composition of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone in a mass ratio of 4:1.

[0085] Example 20, a method for preparing a copper clad laminate, differs from Example 1 in that the curing agent is a composition of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone in a mass ratio of 1:1.

[0086] Example 20, a method for preparing a copper clad laminate, differs from Example 1 in that dodecenylsuccinic anhydride is used as a curing agent.

[0087] Example 21, a method for preparing a copper clad laminate, differs from Example 1 in that 4,4-diaminodiphenyl sulfone is used as a curing agent.

[0088] Comparative Example

[0089] Comparative Example 1, a method for preparing a copper clad laminate, differs from Example 17 in that the low-halogen epoxy resin composition used in the surface layer semi-cured sheet and the core layer semi-cured sheet both uses a low-halogen epoxy resin composition with a modified filler solid content of 50%.

[0090] Comparative Example 2, a method for preparing a copper clad laminate, differs from Example 17 in that the amount of modified filler is adjusted to prepare a low-halogen epoxy resin composition with a filler solid content of 60%; both the surface layer semi-cured sheet and the core layer semi-cured sheet use a low-halogen epoxy resin composition with a filler solid content of 60%.

[0091] Comparative Example 3, a method for preparing a copper clad laminate, differs from Example 17 in that an equal amount of a composition of barium sulfate and aluminum hydroxide in a mass ratio of 1:1 is used to replace the modified filler.

[0092] Performance testing

[0093] Test 1: Heat stress

[0094] According to the IPC-TM-650-2.4.13.1 method, the test cycle is 10S+1 / -0 tin immersion and 10S+1 / -0 cooling at room temperature. The limit cycle number is examined. The longer the time corresponding to the thermal stress obtained by the test, the better the heat resistance of the prepared copper clad laminate.

[0095] Test 2: Peel Strength

[0096] The peel strength of the metal cover layer was tested according to the "after thermal stress" experimental conditions in the IPC-TM-650 2.4.8 method.

[0097] Test 3: Bending Strength

[0098] Test the flexural strength at room temperature according to the method specified in IPC-TM-650 2.4.4 and obtain the flexural modulus.

[0099] Test 4: Comparative Tracking Index (CTI)

[0100] Tested according to GB / T 4207-2022.

[0101] Test samples: The copper clad laminates prepared by the preparation methods of the copper clad laminates of Examples 1 to 22 are used as example samples, and the copper clad laminates prepared by the preparation methods of the copper clad laminates of Comparative Examples 1 to 3 are used as comparative example samples.

[0102] Test results: The test results of thermal stress, relative tracking index, peel strength and bending strength of the copper clad laminates prepared by the preparation methods of the copper clad laminates of Examples 1 to 22 and Comparative Examples 1 to 3 are shown in Table 2.

[0103] The copper clad laminates prepared by the preparation methods of the copper clad laminates of Examples 1 to 22 and Comparative Examples 1 to 3 have flame retardancy of V0 level (UL-94), thermal stress ≥90s, PLC: 0 level (600V), and glass transition temperature Tg ≥150°C (DSC), which meet the standards for microelectronics and multifunctional electronic products in IPC-4101D.

[0104] Table 2. Test results of thermal stress, comparative tracking index, peel strength and bending strength of copper clad laminates prepared by the preparation methods of copper clad laminates of Examples 1 to 22 and Comparative Examples 1 to 3

[0105]

[0106]

[0107] Combining Examples 1 to 22 and Comparative Examples 1 to 3 and Table 2, it can be seen that:

[0108] The copper clad laminates prepared using the preparation methods of the copper clad laminates of Examples 1 to 22 and Comparative Examples 1 to 3 all have excellent thermal stress and relative tracking index (CTI), and the peel strength and bending strength of the copper clad laminates prepared using the preparation methods of the copper clad laminates of Examples 1 to 22 are higher than those of Comparative Examples 1 to 3.

[0109] The reasons for this may be that: there are interface problems between inorganic fillers and epoxy resins, and the content of inorganic fillers is too high, which reduces the adhesion and bending strength of the epoxy resin composition, causing the copper clad laminate to crack easily. In this application, a gradient change in the inorganic filler content of the low-halogen epoxy resin composition in the copper clad laminate is set, and a low-halogen epoxy resin composition with a low solid content of modified fillers is used in the core layer semi-cured sheet, which is beneficial to improving the peel strength and bending strength of the copper clad laminate; a low-halogen epoxy resin composition with a high solid content of modified fillers is used in the surface layer semi-cured sheet, which is beneficial to improving the heat resistance, flame retardancy, arc resistance, and leakage resistance of the copper clad laminate; setting a gradient change in the inorganic filler content of the low-halogen epoxy resin composition in the copper clad laminate reduces the adverse effects of adding fillers or modifying fillers on the peel strength and bending strength of the copper clad laminate.

[0110] The thermal stress, peel strength and bending strength of the copper clad laminates prepared by the preparation method of the copper clad laminates of Examples 1 to 3 are higher than those of Examples 4 to 7, indicating that the use of a borate dispersant in the modified filler to prepare the modified filler improves the interfacial compatibility between the filler and the low-halogen epoxy resin and improves the dispersibility of the filler, so that the prepared copper clad laminates have excellent thermal stress, relative tracking index, peel strength and bending strength.

[0111] The reasons may be that: the prepared borate dispersant contains hydroxyl and carboxyl groups on its molecular chain, which makes the borate dispersant have better dispersibility for fillers; the borate dispersant contains boron element, which has good compatibility with active hydrogen in other raw materials, thereby improving the interaction between the modified filler and the low-halogen epoxy resin; further, the borate dispersant contains carbon-carbon double bonds that react with double-ended hydrogen silicone oil, and the double-ended hydrogen silicone oil can react with vinyl trisbutyl ketoxime silane, thereby further improving the dispersibility, toughness and adhesion of the low-halogen epoxy resin composition; the borate dispersant of the modified filler contains hydroxyl, carboxyl, boron and carbon-carbon double bonds on its molecular chain, which work together to make the modified filler have better dispersibility in the low-halogen epoxy resin, better synergistic performance with the low-halogen epoxy resin and higher adhesion performance, thereby making the prepared copper clad laminate have excellent thermal stress, relative tracking index, peel strength and bending strength.

[0112] The thermal stress, peel strength and bending strength of the copper clad laminates prepared by the preparation method of the copper clad laminates of Examples 8 to 9 are higher than those of Examples 1 to 3 and Examples 10 to 13, indicating that the filler uses a composition of aluminum hydroxide, barium sulfate and boron nitride in a mass ratio of 1:1:(0.2-0.4), and there is a good synergistic effect between aluminum hydroxide, barium sulfate and boron nitride, which improves the thermal stress, peel strength and bending strength of the prepared copper clad laminate.

[0113] The reason may be that barium sulfate, which has toughening, shrinkage resistance, aging resistance, and a low thermal expansion coefficient, is used in combination with aluminum hydroxide, which has good flame retardancy, arc resistance, and tracking resistance, and boron nitride, which has flame retardancy, thermal conductivity, good insulation properties, and is both flexible and rigid. This makes the prepared low-halogen epoxy resin composition have excellent flame retardancy, thermal stability, arc resistance, and tracking resistance.

[0114] Boron nitride has a flaky structure and is compatible with granular aluminum hydroxide and barium sulfate. The modified fillers are interconnected, effectively improving the thermal conductivity of the polymer matrix. There are fewer active groups on the surface of boron nitride. When the content of boron nitride increases relatively, the dispersibility becomes worse, resulting in a decrease in the peel strength and bending strength of the prepared copper clad laminate. At the same time, when the content of boron nitride increases relatively, it is not conducive to the formation of a thermal conductive network, resulting in a decrease in the thermal stability of the copper clad laminate. When the content of boron nitride decreases relatively and the dispersed granular filler increases relatively, the toughness of the prepared low-halogen epoxy resin composition decreases, and the crack resistance, peel strength, flame retardancy, thermal stability, arc resistance, and tracking resistance of the prepared low-halogen epoxy resin composition decrease.

[0115] Compared with graphene oxide, boron nitride has better thermal conductivity, toughness and smaller thermal expansion coefficient, and has better compatibility with aluminum hydroxide and barium sulfate.

[0116] The thermal stress, peel strength and bending strength of the copper clad laminates prepared by the preparation method of the copper clad laminates of Examples 1 to 3 are higher than those of Examples 14 to 17, indicating that the use of vinyl trisbutyl ketoxime silane and hydrogen-containing silicone oil in combination in the low-halogen epoxy resin composition, and preferably the hydrogen-containing silicone oil is a double-terminal hydrogen-containing silicone oil with a hydrogen content of 0.016-0.08%, further improves the thermal stress, peel strength and bending strength of the copper clad laminates.

[0117] The possible reason is that the double-ended hydrogenated silicone oil improves the flexibility of the low-halogen epoxy resin composition, and the vinyl trisbutyl ketoxime silane improves the adhesion performance of the low-halogen epoxy resin composition.

[0118] The higher the hydrogen content of the hydrogen-containing silicone oil, the less conducive it is to improving the toughness of the low-halogen epoxy resin composition; the relatively lower content of vinyl tributyl ketone oxime has a poor effect on improving the adhesion of the low-halogen epoxy resin composition, and has a poor effect on improving the thermal stability, arc resistance, and tracking resistance of the copper clad laminate.

[0119] The thermal stress, peel strength and bending strength of the copper clad laminates prepared by the preparation method of the copper clad laminates of Examples 18 to 19 are higher than those of Examples 1 to 3 and Examples 20 to 22, indicating that the use of a composition of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone in a mass ratio of (2-4):1 as a curing agent in the low-halogen epoxy resin composition further improves the thermal stress, peel strength and bending strength of the copper clad laminates.

[0120] The reason may be that the curing agent using dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone not only allows the low-halogen epoxy resin to be cured at high temperature; but also 4,4-diaminodiphenyl sulfone improves the high-temperature resistance of the low-halogen epoxy resin composition, dodecenylsuccinic anhydride improves the flexibility of the low-halogen epoxy resin composition, and the combination of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone further improves the thermal stress, peel strength and bending strength of the copper clad laminate prepared using the low-halogen epoxy resin composition.

[0121] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing a copper clad laminate, characterized in that: The method comprises the following preparation steps: S1. Preparation of a low-halogen epoxy resin composition: 25-115 parts by mass of a modified filler, 60-80 parts by mass of a low-halogen epoxy resin, and 25-35 parts by mass of a curing agent are stirred and mixed to prepare a low-halogen epoxy resin composition having a modified filler solid content of 20-25% and a low-halogen epoxy resin composition having a modified filler solid content of 30-50% as required; the modified filler is prepared by surface-modifying an inorganic filler with a dispersant; S2. Preparation of surface prepreg and core prepreg: coating the reinforcing material with a low-halogen epoxy resin composition having a solid content of 20-25% of a modified filler to obtain a core prepreg; coating the reinforcing material with a low-halogen epoxy resin composition having a solid content of 30-50% of a modified filler, and drying to obtain a surface prepreg; S3, preparation of copper clad laminate: sequentially stacking copper foil layer, surface prepreg, core layer prepreg, surface prepreg and copper foil layer and pressing at high temperature to prepare copper clad laminate; The preparation process of the modified filler is as follows: The polyol and boric acid are mixed in proportion, stirred and reacted at a temperature of 100-300°C for 3-8 hours to obtain a borate ester; then maleic anhydride is added, and stirred and reacted at 100-300°C for 3-8 hours to prepare a borate ester dispersant; the mass ratio of the polyol, boric acid and maleic anhydride is (1-2): (0.5-1): 1; After uniformly mixing the borate dispersant, the ground filler and water in a mass ratio of (7-10):4:100, stirring and modifying at a temperature of 60-80°C for 3-5 hours to prepare a suspension, then allowing it to stand, filter pressing and drying to prepare a modified filler; The raw materials of the modified filler also include vinyl tributylan oxime silane and hydrogen-containing silicone oil; the mass ratio of the vinyl tributylan oxime silane, hydrogen-containing silicone oil and filler is (0.2-0.4):0.3:4; the hydrogen-containing silicone oil is a double-ended hydrogen-containing silicone oil with a hydrogen content of 0.016-0.08%.

2. The method for preparing a copper clad laminate according to claim 1, wherein: The polyol is one of pentaerythritol, trimethylolethane, xylitol and sorbitol.

3. The method for preparing a copper clad laminate according to claim 1, wherein: The inorganic filler is at least two of aluminum hydroxide, barium sulfate, titanium dioxide, boron nitride, graphene oxide, aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, and silicon carbide.

4. The method for preparing a copper clad laminate according to claim 3, wherein: The inorganic filler is a composition of aluminum hydroxide, barium sulfate and boron nitride in a mass ratio of 1:1:(0.2-0.4).

5. The method for preparing a copper clad laminate according to claim 1, wherein: The curing agent is a composition of dodecenylsuccinic anhydride and 4,4-diaminodiphenyl sulfone in a mass ratio of (2-4):

1.

6. The method for preparing a copper clad laminate according to claim 1, wherein: In the preparation of the surface prepreg and the core prepreg, the drying temperature is 150-170°C and the baking time is 5-8 minutes; in the preparation of the copper clad laminate, the pressing pressure is 30-40 kg / cm 2 , the pressing temperature is 200-250℃, and the pressing time is 3-5h.

7. A copper clad laminate, characterized in that: A copper clad laminate prepared by the method for preparing a copper clad laminate according to any one of claims 1 to 6.

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