A composite ultra-thin adhesive sheet for high-frequency copper-clad plate multilayer pressing and a preparation method thereof

Abstract

The application discloses a kind of composite ultra-thin bonding sheet for high-frequency copper-clad plate multilayer pressing and a preparation method thereof, and specifically belongs to the field of copper-clad plate bonding sheet manufacturing.The composite ultra-thin bonding sheet is obtained by impregnating the reinforcing substrate in a composite resin adhesive and then drying.The composite resin adhesive comprises a composite resin composition and a solvent.The composite resin composition comprises a composite bisphenol A type epoxy resin, an o-cresol formaldehyde epoxy resin, a brominated epoxy resin, poly(4-vinyl butyl benzoate), a heat-resistant filler, a curing agent, and a curing accelerator.The copper-clad plate prepared using the composite ultra-thin adhesive provided by the application has excellent high-temperature resistance and tracking resistance, as well as good flame retardance, low dielectric constant, and peel strength, with excellent overall performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of copper-clad plate bonding sheet manufacturing, and particularly relates to a composite ultrathin bonding sheet for multilayer pressing of high-frequency copper-clad plate and a preparation method thereof. BACKGROUND

[0002] With the rapid development of modern communication technology and the increasing popularity of electronic products, the performance requirements of high-frequency copper-clad plate, an important basic material in the electronic industry, are becoming higher and higher. In particular, in the multilayer pressing process, the performance of the bonding sheet plays a crucial role in the overall performance of the high-frequency copper-clad plate.

[0003] Traditional bonding sheets for multilayer pressing of high-frequency copper-clad plate mostly use thermoplastic or thermosetting resin systems. Although thermoplastic bonding sheets have good flowability 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 plate in complex environments. While thermosetting bonding sheets have good heat resistance and chemical stability, they require high temperature and pressure during processing, and have a long curing time, increasing production costs and process difficulty.

[0004] In order to overcome the above-mentioned shortcomings, the industry has begun to explore and develop a new type of composite bonding sheet for multilayer pressing of high-frequency copper-clad plate. 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 demand of high-frequency signal transmission, the dielectric properties of the bonding sheet also need to meet certain standards.

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

[0006] The present application provides a composite bonding sheet for multilayer pressing of high-frequency copper-clad plate and a preparation method thereof, aiming to solve the problems existing in the prior art and provide a composite ultrathin bonding sheet with excellent performance, simple preparation process, and moderate cost to meet the demand of multilayer pressing process of high-frequency copper-clad plate.

[0007] In order to achieve the above-mentioned purpose, the present application discloses the following technical solutions:

[0008] In the first aspect, the present application provides a composite resin composition, which contains the following components by mass fraction:

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

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

[0011] Brominated epoxy resin 30-40 parts;

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

[0013] Heat-resistant filler 50-60 parts;

[0014] Curing agent 10-12 parts;

[0015] Curing accelerator 0.6-1 part;

[0016] The composite bisphenol A type epoxy resin is prepared from 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 formaldehyde epoxy resin is at least one of o-cresol formaldehyde epoxy CYDCN-205 and o-cresol formaldehyde 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] Further 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 application provides a composite resin adhesive, which comprises the composite resin composition of the first aspect and a solvent, and the mass ratio of the composite resin composition to the solvent is (4-7):1, and the solvent is at least one of methyl ketone, 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 application provides a composite ultra-thin bonding sheet for high-frequency copper-clad plate multi-layer pressing, which is obtained by drying a reinforced substrate impregnated in the composite resin adhesive of the second aspect.

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

[0027] In a fourth aspect, the present application provides a preparation method of the composite ultra-thin adhesive sheet according to the third aspect, comprising the following steps:

[0028] S1. Mix the composite bisphenol A epoxy resin, the o-cresol formaldehyde epoxy resin, the brominated epoxy resin, the poly(4-vinyl butyl benzoate), the heat-resistant filler, the curing agent, the curing accelerator, and the solvent according to the formula amount, and mix them uniformly to obtain the adhesive;

[0029] S2. Dip the reinforcing substrate in the adhesive for 10-15 min, dry it at 100-130 DEG C for 40-60 min, and perform hot roller pressing at 130 DEG C to obtain the composite ultra-thin adhesive sheet, wherein the thickness of the composite ultra-thin adhesive sheet is ≤0.5 mm.

[0030] In the present application:

[0031] Different types of bisphenol A epoxy resins have different heat resistance, and by compounding them, the heat resistance of the adhesive can be improved by comprehensively utilizing the heat resistance advantages of various resins; Bisphenol A epoxy resins will undergo complex chemical reactions during the curing process, and by compounding 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 different types of bisphenol A epoxy resins, the mechanical properties of various resins can be comprehensively utilized to enhance the strength and toughness of the adhesive, therefore, the present application selects multiple types of bisphenol A epoxy resins for compounding, and at the same time, o-cresol formaldehyde epoxy resin, brominated epoxy resin, and poly(4-vinyl butyl benzoate) are selected for compounding, which plays an important role in improving the comprehensive performance of the adhesive.

[0032] After the hydrophobic fumed silica is uniformly dispersed in the adhesive system, a large number of particles form hydrogen bonds through the surface silicon hydroxyl (Si-OH) to form a silica aggregate network, which limits the fluidity of the system and increases the viscosity, thereby playing a thickening role. Under the action of shear force in the preparation process, the hydrogen bonds and the silica network are destroyed, resulting in a decrease in the viscosity of the system, a thixotropy, which facilitates the adhesive to be applied on the reinforced substrate. Once the external force is eliminated, the hydrogen bonds and the silica network are reformed, so that the adhesive is attached to the reinforced substrate, improving the overall stability; the surface of the hydrophobic fumed silica is specially treated to have excellent hydrophobicity. When added to the adhesive, the 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, degrading and other phenomena due to the action of water, oxygen and other environmental factors, thereby improving the weather resistance of the copper-clad plate. Compared with hydrophilic fumed silica, the inclusion of hydrophobic fumed silica in the copper-clad plate adhesive can also improve the mechanical properties of the copper-clad plate.

[0033] Advantages of the present application:

[0034] The composite ultrathin adhesive provided by the present application can be used to prepare a copper-clad plate with high CTI value and high heat resistance. The CTI value of the copper-clad plate can reach more than 750V, the glass transition temperature is more than 200℃, the heat resistance test (288℃ floating welding immersion welding) is more than 210s, and the copper-clad plate has excellent high-temperature resistance and tracking resistance (CTI) performance, as well as good flame retardant performance, low dielectric constant and peel strength, and excellent comprehensive performance. DETAILED DESCRIPTION

[0035] The technical solutions in the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0036] The technical solutions of the present application will be further described in combination with specific embodiments. It should be understood that the following embodiments are only used to explain the present application, and are not used to limit the present application.

[0037] In the present application:

[0038] Bisphenol A type epoxy resin: epoxy resin E-44, epoxy resin E-42 and epoxy resin CYD-012 are all purchased from SINOPEC Baling Petrochemical Company;

[0039] Ortho-cresol novolac epoxy resin: Ortho-cresol novolac CYDCN-205, Ortho-cresol novolac CYDCN-205H, both purchased from SINOPEC Baling Petrochemical Company;

[0040] Poly(4-vinyl butyl benzoate): 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, all purchased from Shandong Kaiji Chemical Technology Co., Ltd.;

[0042] Tetrabromobisphenol A: Traditional reaction type 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, all purchased from Hubei HuiFu Nanometer Material Co., Ltd.;

[0044] Hydrophilic fumed silica: Model HL-200, purchased from Hubei HuiFu Nanometer Material Co., Ltd.;

[0045] Other raw materials can be obtained from the market.

[0046] Preparation of examples and comparative examples

[0047] Step (1), according to the mass fraction in Table 1, the raw materials were weighed, poly(4-vinyl butyl benzoate), brominated epoxy resin, curing agent and curing accelerator were first dissolved in the solvent, then heat-resistant filler was added and stirred uniformly, finally composite bisphenol A type epoxy resin and ortho-cresol novolac epoxy resin were added and mixed, and a high-speed shearing emulsifier was used for high-speed stirring to obtain the adhesive. The mixing process was kept at room temperature;

[0048] Step (2), the glass fiber cloth was immersed in the adhesive for 15 min, then dried at 120℃ for 60 min, and hot rolled at 130℃ to obtain a bonding sheet with a thickness of ≤0.5 mm;

[0049] Step (3), 6 bonding sheets were stacked together, copper foil was covered on the surface of the bonding sheet, and hot pressing was carried out at 170-200℃ for 1.5-2h, and then cutting and shaping were carried out to obtain the copper-clad plate of examples 1-3 and comparative examples 1-9.

[0050] Table 1 Components of examples 1-3 and comparative examples 1-9, mass fraction, preparation process parameters

[0051]

[0052]

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

[0054] To verify the comprehensive performance of the composite resin composition provided by the present application, and to verify that the specific components in the composite resin composition are key necessary components, substitutions or omissions are made on the basis of the formulation of Example 2. For details, refer to the following settings and Table 1:

[0055] Comparative Example 1: A single type of bisphenol A epoxy resin E-44 is used, and the rest is consistent with Example 2;

[0056] Comparative Example 2: A single type of bisphenol A epoxy resin E-42 is used, and the rest is consistent with Example 2;

[0057] Comparative Example 3: A single type of bisphenol A epoxy resin CYD-012 is used, and the rest is consistent with Example 2;

[0058] Comparative Example 4: O-cresol formaldehyde epoxy resin is omitted, and the omitted amount is distributed to bisphenol A epoxy resin, brominated epoxy resin, and poly(4-vinyl butyl benzoate) according to the mass ratio in Example 2, and the rest is consistent with Example 2;

[0059] Comparative Example 5: Composite bisphenol A epoxy resin is omitted, and the omitted amount is distributed to o-cresol formaldehyde epoxy resin, brominated epoxy resin, and poly(4-vinyl butyl benzoate) according to the mass ratio in Example 2, and the rest is consistent with Example 2;

[0060] Comparative Example 6: Brominated epoxy resin is omitted, and 15 parts of the omitted amount is replaced with tetrabromobisphenol A, and 20 parts is distributed to bisphenol A epoxy resin, o-cresol formaldehyde epoxy resin, and poly(4-vinyl butyl benzoate) according to the mass ratio in Example 2, and the rest is consistent with Example 2;

[0061] Comparative Example 7: Brominated epoxy resin is omitted, and the omitted amount is distributed to bisphenol A epoxy resin, o-cresol formaldehyde epoxy resin, and poly(4-vinyl butyl benzoate) according to the mass ratio in Example 2, and the rest is consistent with Example 2;

[0062] Comparative Example 8: Hydrophobic fumed silica is omitted, and the omitted amount is replaced with an equal amount of hydrophilic fumed silica, and the rest is consistent with Example 2;

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

[0064] Performance Test

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

[0066] The test items were as follows:

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

[0068] Peeling strength: tested according to the test standard of IPC-TM-650 2018;

[0069] Glass transition temperature: tested according to the test standard of IPC-TM-650 2018;

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

[0071] Flame retardancy: determined according to the burning method of UL-94;

[0072] Immersion soldering test: tested according to the test standard of IPC-TM-650 2018;

[0073] The results are shown in Table 2.

[0074] Table 2: Performance test results

[0075]

[0076] As can be seen from the results in Table 2, the copper-clad plates of Examples 1-3 have high CTI values, reaching more than 750 V, the glass transition temperatures are all above 200℃, the heat resistance tests (288℃ floating solder immersion soldering) all exceed 210s, and have excellent high-temperature resistance and tracking resistance performance, and also have good flame retardancy and peeling strength, and have excellent comprehensive performance; as can be seen from the results of Comparative Example 2 and Comparative Examples 1-9, selecting a specific ratio of bisphenol A epoxy resin, selecting a specific type of heat-resistant filler, and selecting a specific amount of compounding use of composite bisphenol A epoxy resin, o-cresol formaldehyde epoxy resin, brominated epoxy resin and poly(4-vinyl butyl 4-vinylbenzoate), effectively improve the heat resistance, mechanical properties and CTI performance of the resin adhesive.

[0077] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application 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 replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A composite resin composition, characterized by comprising: The composition comprises the following components by mass fraction: 40-50 parts of a composite bisphenol A type epoxy resin; 40-45 parts of an ortho-cresol formaldehyde epoxy resin; 30-40 parts of a brominated epoxy resin; 10-12 parts of poly(4-vinyl butyl benzoate); 50-60 parts of a heat-resistant filler; 10-12 parts of a curing agent; 0.6-1 part of a curing accelerator; The composite bisphenol A type epoxy resin is 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 ortho-cresol formaldehyde epoxy resin is at least one of ortho-cresol formaldehyde epoxy CYDCN-205 and ortho-cresol formaldehyde 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; The heat-resistant filler is hydrophobic fumed silica.

2. The composite resin composition according to claim 1, characterized by The hydrophobic fumed silica is at least one of HB-132, HB-139, HB-151, and HB-152.

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

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

5. A composite resin adhesive, characterized by comprising: The adhesive comprises the composite resin composition of any one of claims 1-4 and a solvent, and the mass ratio of the composite resin composition to the solvent is (4-7):1, and the solvent is at least one of methyl ketone, acetone, toluene, and xylene.

6. A composite ultra-thin bonding sheet for high-frequency copper-clad board multilayer pressing, characterized by The adhesive sheet is obtained by impregnating a reinforcing substrate in the composite resin adhesive of claim 5 and drying.

7. The composite type ultra-thin bonding sheet for high frequency copper clad plate multi-layer press bonding according to claim 6, characterized in that, The reinforcing substrate is at least one of glass fiber cloth, synthetic fiber cloth, non-woven fabric, and laminate base paper.

8. The method for preparing the composite ultrathin adhesive sheet according to claim 7, characterized in that, The method comprises the following steps: S1. uniformly mixing the composite bisphenol A type epoxy resin, the ortho-cresol formaldehyde epoxy resin, the brominated epoxy resin, poly(4-vinyl butyl benzoate), the heat-resistant filler, the curing agent, the curing accelerator, and the solvent according to the formula amount to obtain the adhesive; S2. impregnating the reinforcing substrate in the adhesive for 10-15 min, drying at 100-130°C for 40-60 min, and performing hot roller pressing at 130°C to obtain the composite ultra-thin adhesive sheet, and the thickness of the composite ultra-thin adhesive sheet is ≤0.5 mm.

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