Composite ultrathin bonding sheet for multi-layer lamination of high-frequency copper-clad plate and preparation method of composite ultrathin bonding sheet

Abstract

The invention discloses a composite ultrathin bonding sheet for multi-layer lamination of a high-frequency copper-clad plate and a preparation method of the composite ultrathin bonding sheet, and particularly belongs to the field of copper-clad plate bonding sheet manufacturing. The composite ultrathin bonding sheet is obtained by dipping a reinforced base material in a composite resin adhesive and drying the composite resin adhesive. The composite resin adhesive comprises a composite resin composition and a solvent, the composite resin composition comprises composite bisphenol A epoxy resin, o-cresol formaldehyde epoxy resin, brominated epoxy resin, poly (4-vinyl n-butyl benzoate), heat-resistant filler, a curing agent and a curing accelerator. A copper-clad plate prepared from the composite ultrathin adhesive provided by the invention has excellent high temperature resistance and tracking resistance, and also has better flame retardance, lower dielectric constant and peel strength and excellent comprehensive performance.

Description

Technical Field

[0001] The invention belongs to the field of copper clad laminate bonding sheet manufacturing, and in particular relates to a composite ultra-thin bonding sheet for multi-layer lamination of high-frequency copper clad laminates and a preparation method thereof. Background Art

[0002] With the rapid development of modern communication technology and the increasing popularity of electronic products, high-frequency copper clad laminates, as important basic materials in the electronics industry, have higher and higher performance requirements. Especially in the multi-layer lamination process, the performance of the bonding sheet plays a vital role in the overall performance of the high-frequency copper clad laminate.

[0003] Traditional bonding sheets for multi-layer lamination of high-frequency copper clad laminates mostly use thermoplastic or thermosetting resin systems. Although thermoplastic bonding sheets have good fluidity and filling properties during processing, their heat resistance and chemical stability are relatively poor, making it difficult to meet the use requirements of high-frequency copper clad laminates in complex environments. Although thermosetting bonding sheets have good heat resistance and chemical stability, they require higher temperatures and pressures during processing, and take longer to cure, increasing production costs and process difficulty.

[0004] In order to overcome the above shortcomings, the industry has begun to explore and develop a new type of composite bonding sheet for high-frequency copper clad laminate multilayer lamination. This bonding sheet needs to have excellent heat resistance, chemical stability, processing performance and good interlayer bonding strength. At the same time, in order to meet the needs of high-frequency signal transmission, the dielectric properties of the bonding sheet also need to meet certain standards.

[0005] However, the existing composite bonding sheets often have some problems in the preparation process, such as unreasonable raw material ratio, complex preparation process, high cost, etc. These problems limit the wide application and further development of the composite bonding sheets. Summary of the invention

[0006] The present invention provides a composite bonding sheet for multi-layer lamination of high-frequency copper clad laminates and a preparation method thereof, aiming to solve the problems existing in the prior art and provide a composite ultra-thin bonding sheet with excellent performance, simple preparation process and moderate cost to meet the requirements of the multi-layer lamination process of high-frequency copper clad laminates.

[0007] In order to achieve the above object, the present invention discloses the following technical solutions:

[0008] In a first aspect, the present invention provides a composite resin composition, which comprises the following components in parts by mass:

[0009] 40-50 parts of composite bisphenol A epoxy resin;

[0010] 40-45 parts of o-cresol epoxy resin;

[0011] 30-40 parts of brominated epoxy resin;

[0012] Poly (n-butyl 4-vinylbenzoate) 10-12 parts;

[0013] 50-60 parts of heat-resistant filler;

[0014] 10-12 parts of curing agent;

[0015] Curing accelerator 0.6-1 part;

[0016] The composite bisphenol A epoxy resin is composed of epoxy resin E-44, epoxy resin E-42, and epoxy resin CYD-012 in a mass ratio of 1:(1-2):(0.3-0.5);

[0017] The o-cresol epoxy resin is at least one of o-cresol epoxy CYDCN-205 and o-cresol epoxy CYDCN-205H;

[0018] The brominated epoxy resin is at least one of brominated epoxy KJB-400T60, brominated epoxy KJB-400T80, and brominated epoxy KJB-400A80.

[0019] Preferably, the heat-resistant filler is hydrophobic fumed silica.

[0020] More preferably, the hydrophobic fumed silica is at least one of HB-132, HB-139, HB-151, and HB-152.

[0021] Preferably, the curing agent is at least one of dicyandiamide, boron trifluoride monoethylamine and boron trifluoride aniline.

[0022] Preferably, the curing accelerator is at least one of 2-methylimidazole and 2-ethyl-4-methylimidazole.

[0023] In a second aspect, the present invention provides a composite resin adhesive, which comprises the composite resin composition described in the first aspect and a solvent, wherein the mass ratio of the composite resin composition to the solvent is (4-7):1, and the solvent is at least one of butanone, acetone, toluene, and xylene.

[0024] Preferably, the mass ratio of the composite resin composition to the solvent is 5:1.

[0025] In a third aspect, the present invention provides a composite ultra-thin bonding sheet for multi-layer lamination of high-frequency copper-clad laminates, wherein the bonding sheet is obtained by impregnating a reinforced substrate in the composite resin adhesive described in the second aspect and then drying the resulting adhesive.

[0026] Preferably, the reinforcing substrate is at least one of glass fiber cloth, synthetic fiber cloth, non-woven fabric, and laminate base paper.

[0027] In a fourth aspect, the present invention provides a method for preparing the composite ultra-thin bonding sheet according to the third aspect, comprising the following steps:

[0028] S1. According to the formula, the composite bisphenol A epoxy resin, o-cresol epoxy resin, brominated epoxy resin, poly (4-vinyl benzoic acid n-butyl ester), heat-resistant filler, curing agent, curing accelerator, and solvent are uniformly mixed to obtain an adhesive;

[0029] S2. The reinforced substrate is immersed in the adhesive for 10-15 minutes, dried at 100-130°C for 40-60 minutes, and hot roller pressed at 130°C to obtain a composite ultra-thin bonding sheet, wherein the thickness of the composite ultra-thin bonding sheet is ≤0.5 mm.

[0030] In the present invention:

[0031] Different types of bisphenol A epoxy resins have different heat resistances. By compounding and using them, the heat resistance advantages of various resins can be combined to improve the heat resistance of the adhesive. Bisphenol A epoxy resins will undergo complex chemical reactions during the curing process. By compounding and using different types of epoxy resins, the rate and conditions of the curing reaction can be adjusted to make the adhesive more stable during the curing process. By compounding and using different types of bisphenol A epoxy resins, the mechanical property advantages of various resins can be combined to enhance the strength and toughness of the adhesive. Therefore, the present invention selects multiple types of bisphenol A epoxy resins for compounding and use, and simultaneously selects and uses them in compound with o-cresol epoxy resin, brominated epoxy resin and poly (4-vinyl benzoic acid n-butyl ester). Such selection plays an important role in improving the comprehensive performance of the adhesive.

[0032] After the hydrophobic fumed silica is evenly dispersed in the adhesive system, a large number of particles form hydrogen bonds through the surface silanol (Si-OH) to form a silica aggregate network, which limits the fluidity of the system and increases the viscosity, thereby playing a thickening role. During the preparation process, under the action of shear force, the hydrogen bonds and the silica network are destroyed, resulting in a decrease in the viscosity of the system and thixotropy, which facilitates the adhesive to be glued on the reinforced substrate. Once the external force is eliminated, the hydrogen bonds and the silica network are re-formed, allowing the adhesive to adhere to the reinforced substrate and improve the overall stability; the surface of the hydrophobic fumed silica is specially treated to give it excellent hydrophobicity. When added to the adhesive, this hydrophobicity can effectively prevent the penetration and erosion of water molecules, thereby improving the water resistance of the adhesive, and can also effectively prevent the adhesive from aging and degradation due to environmental factors such as moisture and oxygen, thereby improving the weather resistance of the copper clad laminate. Compared with hydrophilic fumed silica, the inclusion of hydrophobic fumed silica in the copper clad laminate adhesive can also improve the mechanical properties of the copper clad laminate.

[0033] Beneficial effects of the present invention:

[0034] The composite ultra-thin adhesive provided by the present invention can be used to prepare a copper-clad laminate with a high CTI value and high heat resistance, wherein the CTI value can reach above 750V, the glass transition temperature is above 200°C, the heat resistance test (288°C solder float and solder dip) is above 210s, and the laminate has excellent high temperature resistance and tracking resistance (CTI) performance, and also has good flame retardant performance, low dielectric constant and peel strength, and excellent comprehensive performance. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0037] In the present invention:

[0038] Bisphenol A type epoxy resin: Epoxy resin E-44, epoxy resin E-42 and epoxy resin CYD-012 were purchased from Sinopec Baling Petrochemical Company;

[0039] o-Cresol epoxy resin: o-Cresol CYDCN-205 and o-Cresol CYDCN-205H were purchased from Sinopec Baling Petrochemical Company;

[0040] Poly (4-vinylbenzoic acid n-butyl ester): model YH83588, purchased from Hangzhou Yuhao Chemical Technology Co., Ltd.;

[0041] Brominated epoxy resin: Brominated epoxy KJB-400T60, Brominated epoxy KJB-400T80, Brominated epoxy KJB-400A80 were purchased from Shandong Kaiji Chemical Technology Co., Ltd.;

[0042] Tetrabromobisphenol A: traditional reactive flame retardant, model KBP-200A, purchased from Shandong Kaiji Chemical Technology Co., Ltd.;

[0043] Hydrophobic fumed silica: Model HB-132, Model HB-139, Model HB-151, Model HB-152 were all purchased from Hubei Huifu Nanomaterials Co., Ltd.;

[0044] Hydrophilic fumed silica: Model HL-200, purchased from Hubei Huifu Nanomaterials Co., Ltd.;

[0045] Other raw materials are commercially available.

[0046] Preparation of Examples and Comparative Examples

[0047] Step (1), weighing the raw materials according to the mass fractions in Table 1, first dissolving poly (4-vinyl benzoic acid n-butyl ester), brominated epoxy resin, curing agent and curing accelerator in a solvent, then adding a heat-resistant filler and stirring evenly, finally adding a composite bisphenol A epoxy resin and an o-cresol epoxy resin and mixing, and stirring evenly at high speed using a high-speed shear emulsifier to obtain an adhesive, and keeping the room temperature unchanged during the mixing process;

[0048] Step (2), immersing the glass fiber cloth in the adhesive for 15 minutes, drying at 120° C. for 60 minutes, and hot rolling at 130° C. to obtain an adhesive sheet with a thickness of ≤0.5 mm;

[0049] Step (3), stacking 6 adhesive sheets together, covering the adhesive sheets with copper foil, hot pressing at 170-200° C. for 1.5-2 h, cutting and shaping, and obtaining copper clad laminates of Examples 1-3 and Comparative Examples 1-9.

[0050] Table 1 Components and their mass ratios, preparation process parameters of Examples 1-3 and Comparative Examples 1-9

[0051]

[0052]

[0053] Note: “——” in the table means no component is added.

[0054] In order to verify the comprehensive performance of the composite resin composition provided by the present invention, and to verify that the specific components in the composite resin composition are key necessary components, replacement or omission is performed on the basis of the formula of Example 2, with specific reference to the following settings and Table 1:

[0055] Comparative Example 1: Bisphenol A epoxy resin uses a single type of resin E-44, and the rest is the same as Example 2;

[0056] Comparative Example 2: Bisphenol A epoxy resin uses a single type of resin E-42, and the rest is the same as Example 2;

[0057] Comparative Example 3: Bisphenol A epoxy resin uses a single type of resin CYD-012, and the rest is the same as Example 2;

[0058] Comparative Example 4: o-cresol-formaldehyde epoxy resin is missing, and the missing amount is allocated to bisphenol A epoxy resin, brominated epoxy resin, and poly (4-vinyl benzoic acid n-butyl ester) according to the mass ratio in Example 2, and the rest is consistent with Example 2;

[0059] Comparative Example 5: The composite bisphenol A epoxy resin is missing, and the missing amount is allocated to o-cresol epoxy resin, brominated epoxy resin, and poly (4-vinyl benzoic acid n-butyl ester) according to the mass ratio in Example 2, and the rest is consistent with Example 2;

[0060] Comparative Example 6: brominated epoxy resin was missing, 15 parts of the missing amount was replaced with tetrabromobisphenol A, and 20 parts were distributed to bisphenol A epoxy resin, o-cresol epoxy resin, and poly (4-vinyl benzoic acid n-butyl ester) according to the mass ratio in Example 2, and the rest was consistent with Example 2;

[0061] Comparative Example 7: The brominated epoxy resin is missing, and the missing amount is allocated to bisphenol A epoxy resin, o-cresol epoxy resin, and poly (4-vinyl benzoic acid n-butyl ester) according to the mass ratio in Example 2, and the rest is consistent with Example 2;

[0062] Comparative Example 8: The hydrophobic fumed silica was missing, and the missing amount was replaced with an equal amount of hydrophilic fumed silica, and the rest was consistent with Example 2;

[0063] Comparative Example 9: Poly(n-butyl 4-vinylbenzoate) is missing, and the missing amount is distributed to bisphenol A epoxy resin, o-cresol epoxy resin, and brominated epoxy resin according to the mass ratio in Example 2. The rest is consistent with Example 2.

[0064] Performance Testing

[0065] The copper clad laminates prepared in Examples 1-4 and Comparative Examples 1-9 were subjected to performance tests;

[0066] The test items are as follows:

[0067] CTI value: Tested according to the IEC-112 standard method;

[0068] Peel strength: tested in accordance with the IPC-TM-650 2018 test standard;

[0069] Glass transition temperature: tested in accordance with the IPC-TM-650 2018 test standard;

[0070] Dielectric constant and dielectric loss: tested according to ASTM D150;

[0071] Flame retardancy: measured according to UL-94 combustion method;

[0072] Dip soldering test: Tested in accordance with the IPC-TM-650 2018 test standard;

[0073] The results are shown in Table 2.

[0074] Table 2 Performance test results

[0075]

[0076] From the results in Table 2, it can be seen that the copper clad laminates of Examples 1-3 have a high CTI value, reaching more than 750V, the glass transition temperature is all above 200°C, and the heat resistance test (288°C solder float and solder dip) is more than 210s, and has excellent high temperature resistance and tracking resistance, as well as good flame retardant properties and peel strength, and excellent comprehensive performance; By comparing the results of Example 2 with those of Comparative Examples 1-9, it can be seen that selecting a specific ratio of bisphenol A epoxy resin, selecting a specific type of heat-resistant filler, and selecting to compound the composite bisphenol A epoxy resin, o-cresol epoxy resin, brominated epoxy resin and poly (4-vinyl benzoic acid n-butyl ester) in a specific dosage ratio plays a key role in effectively improving the heat resistance, mechanical properties and CTI performance of the resin adhesive.

[0077] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A composite resin composition, characterized in that The composition comprises the following components in parts by mass: 40-50 parts of composite bisphenol A epoxy resin; 40-45 parts of o-cresol epoxy resin; 30-40 parts of brominated epoxy resin; Poly (n-butyl 4-vinylbenzoate) 10-12 parts; 50-60 parts of heat-resistant filler; 10-12 parts of curing agent; Curing accelerator 0.6-1 part; The composite bisphenol A epoxy resin is composed of epoxy resin E-44, epoxy resin E-42, and epoxy resin CYD-012 in a mass ratio of 1:(1-2):(0.3-0.5); The o-cresol epoxy resin is at least one of o-cresol epoxy CYDCN-205 and o-cresol epoxy CYDCN-205H; The brominated epoxy resin is at least one of brominated epoxy KJB-400T60, brominated epoxy KJB-400T80, and brominated epoxy KJB-400A80.

2. The composite resin composition according to claim 1, characterized in that The heat-resistant filler is hydrophobic fumed silica.

3. The composite resin composition according to claim 2, characterized in that: The hydrophobic fumed silica is at least one of HB-132, HB-139, HB-151, and HB-152.

4. The composite resin composition according to claim 1, characterized in that The curing agent is at least one of dicyandiamide, boron trifluoride monoethylamine and boron trifluoride aniline.

5. The composite resin composition according to claim 1, characterized in that: The curing accelerator is at least one of 2-methylimidazole and 2-ethyl-4-methylimidazole.

6. A composite resin adhesive, characterized in that: The adhesive comprises the composite resin composition according to any one of claims 1 to 5 and a solvent, the mass ratio of the composite resin composition to the solvent is (4-7):1, and the solvent is at least one of butanone, acetone, toluene and xylene.

7. A composite ultra-thin adhesive sheet for multi-layer lamination of high-frequency copper-clad laminates, characterized in that: The bonding sheet is obtained by dipping a reinforcing substrate into the composite resin adhesive according to claim 6 and then drying the same.

8. The composite ultra-thin bonding sheet for multi-layer lamination of high-frequency copper-clad laminates according to claim 7, characterized in that: The reinforcing substrate is at least one of glass fiber cloth, synthetic fiber cloth, non-woven fabric, and laminate base paper.

9. The method for preparing the composite ultra-thin bonding sheet according to claim 8, characterized in that: The following steps are involved: S1. According to the formula, the composite bisphenol A epoxy resin, o-cresol epoxy resin, brominated epoxy resin, poly (4-vinyl benzoic acid n-butyl ester), heat-resistant filler, curing agent, curing accelerator, and solvent are uniformly mixed to obtain an adhesive; S2. The reinforced substrate is immersed in the adhesive for 10-15 minutes, dried at 100-130°C for 40-60 minutes, and hot roller pressed at 130°C to obtain a composite ultra-thin bonding sheet, wherein the thickness of the composite ultra-thin bonding sheet is ≤0.5 mm.

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