Resin for high-frequency high-speed copper-clad plate and polymerization method thereof

Abstract

The application belongs to the technical field of high-performance resin preparation, and particularly discloses a resin for high-frequency high-speed copper-clad plate and a polymerization method thereof.The structural formula of the resin is: wherein R1 is a group containing a benzocyclobutene, and R2 is a hydrogen, an alkyl group, a hydroxyl group, an alkoxy group or the like; the resin is obtained by copolymerization of an unsaturated resin and a benzocyclobutene containing an alkenyl group substituent group, and the obtained resin has high crosslinking density, extremely low dielectric loss, good moisture resistance and heat resistance and mechanical properties, and is applied to high-frequency high-speed copper-clad plates.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resin preparation, and particularly relates to a resin for high-frequency high-speed copper-clad plate and a polymerization method thereof. BACKGROUND

[0002] With the rapid development of electronic information, the domestic high-frequency high-speed copper-clad plate market has developed rapidly. High-frequency copper-clad plate is mainly used in 5G antenna systems, automotive ADAS systems, cloud server IDC and high-end routers and other fields. However, the current domestic high-frequency high-speed copper-clad plate market is still dominated by imported products. With the breakthrough of domestic enterprises in high-frequency high-speed copper-clad plate technology, the future of domestic substitution will accelerate.

[0003] High-frequency high-speed copper-clad plate requires low dielectric constant and low dielectric loss. The type of resin in the dielectric layer has a decisive influence on the dielectric loss and dielectric constant of the CCL. Generally, high frequency can be defined as a frequency above 1 GHz. High-frequency high-speed copper-clad plate uses special resin, which is divided into thermoplastic resin and thermosetting resin according to its thermal state. The material requirements are as follows: 1. The dielectric loss must be small, otherwise it will affect the quality of signal transmission. The smaller the dielectric loss, the smaller the signal loss. 2. The water absorption should be low. High water absorption will affect the dielectric constant and dielectric loss when wet. 3. The dielectric constant must be small and stable. High dielectric constant can easily cause signal transmission delay. 4. The thermal expansion coefficient of copper foil should be consistent as much as possible, otherwise it will cause copper foil separation in cold and hot changes. 5. Other heat resistance, chemical resistance, impact strength, peel strength, etc. must be good.

[0004] Benzocyclobutene resin, as a new type of active resin, can form thermoplastic resin and thermosetting resin, and has excellent thermal stability, molding processability, low dielectric constant (K), low water absorption and low thermal expansion coefficient. However, single benzocyclobutene resin material cannot meet the comprehensive requirements of high-frequency high-speed copper-clad plate material application, so it is necessary to introduce other groups to improve the performance of benzocyclobutene resin.

[0005] At present, the prepolymerization of benzocyclobutene resin is carried out by using organic solvent and initiator for reaction. Therefore, it is an important research topic of the present application to obtain a resin with good comprehensive performance such as toughness, dielectric performance and moisture resistance by introducing other groups through a simple and low-cost synthesis process. SUMMARY

[0006] In view of the shortcomings of the existing technology, pure benzocyclobutene (BCB) resin cannot completely meet the comprehensive requirements of high-frequency high-speed copper-clad plate material application. The present application provides a resin with strong comprehensive performance for high-frequency high-speed copper-clad plate and a polymerization method thereof.

[0007] In order to achieve the above object, the technical scheme adopted by the present application is:

[0008] The present application provides a resin for high-frequency high-speed copper-clad plate, the structure of the resin is:

[0009]

[0010] wherein R1 is a benzocyclobutene-containing group; R2 is hydrogen, alkyl, hydroxyl or alkoxy; 1 < n < 10000, the larger n is, the higher the polymerization degree is, the flowability of the polymer molecule decreases, which is not conducive to the uniformity of the cured film, therefore, 2 < n < 1000 is preferred.

[0011] Preferably, the structure of the monomer before polymerization in the present application is:

[0012]

[0013] wherein the substitution site of the olefin group connected with R4 on the benzene ring is not limited, and the olefin bond in R1 is broken to participate in polymerization in the polymerization process.

[0014] R3 is oxygen or an olefin group; when R3 is oxygen, R4 is a group containing an unsaturated bond; when R3 is an olefin group, R4 is hydrogen, a vinyl group, an alkyl group, an alkoxy group, a halogen or an amino group, and the olefin bond in R1 is broken to participate in polymerization in the polymerization process.

[0015] Further, the monomer structure of R1 is one of the following I-III:

[0016]

[0017]

[0018] wherein R is hydrogen, an alkyl group, an alkoxy group, a halogen or an amino group.

[0019] The present application also provides a polymerization method for the resin for high-frequency high-speed copper-clad plate, which is to polymerize benzocyclobutene monomer and unsaturated resin, dissolve them in an organic solvent in a certain proportion, add an initiator and stir to raise the temperature to 60-190℃ for 3-24h to obtain a prepolymer. Then, the prepolymer is heated to 190-250℃ under nitrogen protection, and kept for 1-3h to obtain a completely cured resin.

[0020] The characteristic structure of the benzocyclobutene monomer is as follows:

[0021]

[0022] wherein R3 is oxygen or an olefin group; when R3 is oxygen, R4 is a group containing an unsaturated bond; when R3 is an olefin group, R4 is hydrogen, a vinyl group, an alkyl group, an alkoxy group, a halogen or an amino group.

[0023] The unsaturated resin described in the present application is a resin containing at least two unsaturated bonds in each unit, including but not limited to one of 1,2-polybutadiene and 1,2-polyisoprene.

[0024] The benzocyclobutene monomer described in the present application can be polymerized with the unsaturated resin in any mass ratio, preferably in a ratio of (1-10):0.5 (W:W).

[0025] The organic solvent is one of acetonitrile, tetrahydrofuran, toluene, xylene, trimethylbenzene, decaline and N,N'-dimethylformamide.

[0026] The initiator described in the present application is one of bis-tert-butyl peroxyisopropylbenzene, methyl ethyl ketone peroxide, azobisisobutyronitrile, ammonium persulfate and cyclohexanone peroxide.

[0027] Compared with the prior art, the present application has the advantages and beneficial effects that:

[0028] The present application introduces a benzene alkenyl bond on the benzene ring of benzocyclobutene, and the presence of the benzene ring increases the rotational barrier in the molecular chain segment, so that the macromolecular chain is rigid, and the resin has excellent impact resistance; the structural glue is regular and symmetrical, and has a high glass transition temperature. In addition, the application of the benzocyclobutene resin in the copper-clad plate also needs to be pre-polymerized into a pre-polymer with a certain molecular weight: containing an alkenyl bond, the molecular weight can be adjusted according to the pre-polymerization process, which is convenient for later processing into a film; at the same time, an oligomer with excellent dielectric properties and low water absorption is designed and introduced for copolymerization. The polydiene material does not contain a polar group, has good dielectric properties, low water absorption and good flexibility. The copolymerization of the oligomeric diene and the benzocyclobutene monomer obtains a resin with high crosslinking density after curing, which can improve the toughness of the benzocyclobutene resin after curing.

[0029] The resin obtained by the present application has excellent performance, high crosslinking density, extremely low dielectric loss, good moisture resistance and mechanical properties. The polymerization method of the present application is simple to operate and low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a pre-polymer sample preparation diagram in the present application;

[0031] Figure 2 is a glass fiber impregnated semi-cured sheet in the present application;

[0032] Figure 3 is a single-sided copper-clad laminated board prepared in the present application;

[0033] Figure 4 is a double-sided copper-clad laminated board prepared in the present application;

[0034] Figure 5 is a resin film 1 containing laminated plate obtained by the embodiment 1 of the present application;

[0035] Figure 6 is a resin film 2 containing laminated plate obtained by the embodiment 2 of the present application;

[0036] Figure 7 is a resin film 3 containing laminated plate obtained by the embodiment 3 of the present application;

[0037] Figure 8 is a resin film 4 containing laminated plate obtained by the embodiment 4 of the present application;

[0038] Figure 9 is a resin film 5 containing laminated plate obtained by the comparative example 1 of the present application;

[0039] Figure 10 is a resin film 6 containing laminated plate obtained by the comparative example 2 of the present application;

[0040] Figure 11 is a DSC reaction curve diagram of resin 1 prepolymer prepared by the present application;

[0041] Figure 12 is a DSC reaction curve diagram of resin 2 prepolymer prepared by the present application;

[0042] Figure 13 is a DSC reaction curve diagram of resin 3 prepolymer prepared by the present application;

[0043] Figure 14 is an infrared spectrum diagram of resin prepolymer prepared by the present application. DETAILED DESCRIPTION

[0044] The applicant will combine specific embodiments and drawings to make detailed description of the technical solutions of the present application, so that the person skilled in the art can clearly understand the present application. However, the following examples should not be interpreted in any way as a limitation on the scope of protection claimed by the claims of the present application.

[0045] The technical solutions of the present application will be further illustrated by specific embodiments.

[0046] The monomer preparation of the prepolymer is as follows:

[0047]

[0048] Benzocyclobutene monomer 1, its synthesis method refers to patent application No. 202210910836.X, named a benzocyclobutene monomer of phenyl ether and its synthesis method.

[0049]

[0050] Benzocyclobutene monomer 2, the synthesis method of which is described in the reference: Prog. Polym. Sci., Vol. 18, 85-185, 1993. P110-112.

[0051]

[0052] Benzocyclobutene monomer 3, the synthesis method of which is described in the patent application No. 202210284439.6, entitled Benzocyclobutene monomers, benzocyclobutene resins and preparation thereof, low dielectric materials and application thereof.

[0053] Example 1

[0054] Preparation of resin 1 (pre-polymerization): A 50ml three-necked flask was charged with benzocyclobutene monomer 1 (5g) and 1,2-polybutadiene 10g (molecular weight 1000), solvent trimethylbenzene (30ml), initiator di-tert-butyl peroxyisopropylbenzene 0.05g, vacuum extraction and nitrogen protection were repeated for 3 times, and then the reaction was carried out under the condition of N2 protection and condensation reflux at 165℃ for 10h. After the reaction was completed, the reaction viscosity became large, methanol was added for precipitation, and then the white powder was obtained by filtration, which was the pre-polymer of resin 1. The polymerization reaction formula is as follows:

[0055]

[0056] Example 2

[0057] Preparation of resin 2 (pre-polymerization): A 50ml three-necked flask was charged with benzocyclobutene monomer 1 (5g) and 1,2-polyisoprene 10g (molecular weight 2000), solvent trimethylbenzene (30ml), initiator di-tert-butyl peroxyisopropylbenzene (BIPB) 0.05g, vacuum extraction and nitrogen protection were repeated for 3 times, and then the reaction was carried out under the condition of N2 protection and condensation reflux at 65℃ for 10h. After the reaction was completed, the reaction viscosity became large, methanol was added for precipitation, and then the white powder was obtained by filtration, which was the pre-polymer of resin 2. The polymerization reaction formula is as follows:

[0058]

[0059] Example 3

[0060] Preparation of resin 3 (pre-polymerization): A 50ml three-necked flask was charged with benzocyclobutene monomer 2 (5g) and 1,2-polybutadiene 10g (molecular weight 1000), solvent trimethylbenzene (30ml), initiator di-tert-butyl peroxyisopropylbenzene 0.06g, vacuum extraction and nitrogen protection were repeated for 3 times, and then the reaction was carried out under the condition of N2 protection and condensation reflux at 165℃ for 15h. After the reaction was completed, the reaction viscosity became large, methanol was added for precipitation, and then the white powder was obtained by filtration, which was the pre-polymer of resin 3. The polymerization reaction formula is as follows:

[0061]

[0062] Example 4

[0063] Preparation of resin 4 (pre-polymer): A 50ml three-necked flask was charged with benzocyclobutene monomer 3 (5g) and 1,2-polybutadiene (10g, molecular weight 1000), solvent trimethylbenzene (30ml), initiator di-tert-butyl peroxyisopropylbenzene (0.05g), vacuumed and purged with nitrogen for 3 times, then reacted under N2 protection at 165℃ with condenser reflux for 10h. The reaction was ended and the viscosity of the reaction was increased, then methanol was added for precipitation, and the white powder was obtained by filtration. The pre-polymer of resin 4 was obtained. The polymerization reaction formula was as follows:

[0064]

[0065] Example 5

[0066] Preparation of resin 5 (pre-polymer): A 50ml three-necked flask was charged with benzocyclobutene monomer 1 (10g) and trimethylbenzene (30ml), initiator di-tert-butyl peroxyisopropylbenzene (0.1g), vacuumed and purged with nitrogen for 3 times, then reacted under N2 protection at 165℃ with condenser reflux for 15h. The reaction was ended and the viscosity of the reaction was increased, then methanol was added for precipitation, and the white powder was obtained by filtration. The pre-polymer of resin 5 was obtained. The polymerization reaction formula was as follows:

[0067]

[0068] Example 6

[0069] Preparation of resin 6 (pre-polymer): A 50ml three-necked flask was charged with benzocyclobutene monomer 2 (10g) and trimethylbenzene (30ml), initiator di-tert-butyl peroxyisopropylbenzene (0.1g), vacuumed and purged with nitrogen for 3 times, then reacted under N2 protection at 165℃ with condenser reflux for 15h. The reaction was ended and the viscosity of the reaction was increased, then methanol was added for precipitation, and the white powder was obtained by filtration. The pre-polymer of resin 6 was obtained. The polymerization reaction formula was as follows:

[0070]

[0071] The pre-polymers prepared in Examples 1-4 have the following advantages: (1) simple synthesis operation and low cost; (2) excellent dielectric properties; (3) large performance adjustment space; (4) adjustable mechanical properties.

[0072] The effects of the pre-polymers of the resins obtained in Examples 1-6 are further illustrated by application examples.

[0073] In the practical application of high-frequency high-speed copper-clad plate, the resin prepolymer is heated and cured to prepare an organic dielectric material. The specific operation is as follows: the reinforcing material (electronic grade glass fiber cloth 7628) is immersed in a xylene solution containing 65 wt% resin prepolymer, see Figure 1 The xylene solvent is removed by baking in an oven at 155°C for 5 minutes to obtain a prepreg, see Figure 2 Two or more prepregs are stacked to form a prepreg, and then a copper foil is attached to the opposite surfaces of the prepreg. The hot pressing is carried out in a press under a nitrogen atmosphere at a temperature of 220°C and a pressure of 3 MPa for 1.5 hours to obtain a single-sided copper-clad laminate and a double-sided copper-clad laminate containing a resin film, see Figures 3-4 .

[0074] Example 1: The prepolymer of resin 1 is prepared into a prepreg according to the above operation, and then into a laminate, see Figure 5 .

[0075] Example 2: The prepolymer of resin 2 is prepared into a prepreg according to the above operation, and then into a laminate, see Figure 6 .

[0076] Example 3: The prepolymer of resin 3 is prepared into a prepreg according to the above operation, and then into a laminate, see Figure 7 .

[0077] Example 4: The prepolymer of resin 4 is prepared into a prepreg according to the above operation, and then into a laminate, see Figure 8 .

[0078] Comparative Example 1: The prepolymer of resin 5 is prepared into a prepreg according to the above operation, and then into a laminate, see Figure 9 .

[0079] Comparative Example 2: The prepolymer of resin 6 is prepared into a prepreg according to the above operation, and then into a laminate, see Figure 10 .

[0080] The laminates obtained in Examples 1-4 and Comparative Examples 1-2 are tested for performance, and the experimental results are shown in Table 1 below. The instruments and equipment used are shown in Table 2 below. By comparing the examples and comparative examples, the resins used in Comparative Examples 1-2 are obtained by self-polymerization of BCB monomers containing unsaturated bonds, which meet the requirements of low dielectric materials, but have some shortcomings in mechanical properties (such as peel strength). The resins used in Examples 1-4 are obtained by polymerization of BCB monomers containing unsaturated bonds and unsaturated resins, which have good peel strength and bending strength, and are more suitable for use in high-frequency high-speed copper-clad plates.

[0081] Table 1

[0082]

[0083]

[0084] Table 2. List of Testing Instruments and Equipment

[0085] Equipment name Model Electronic universal testing machine 01 5KN 10KN High frequency dielectric constant tester AET hollow resonant cavity Halogen rapid moisture tester JT-80

[0086] Meanwhile, the prepolymers of resins 1-3 prepared in the embodiments of the present invention were subjected to DSC and infrared spectroscopy tests. For the DSC test results of the prepolymer of resin 1, please refer to [link to DSC test results]. Figure 11 ,from Figure 11 It can be seen that the glass transition temperature (Tg) of the prepolymer of resin 1 is 85.9℃, and the ring-opening temperature is 215-257℃, indicating that the prepolymer has the necessary conditions for curing into resin. For the DSC test results of the prepolymer of resin 2, please refer to [reference needed]. Figure 12 ,from Figure 12 It can be seen that the glass transition temperature (Tg) of the prepolymer of resin 2 is 150℃, and the ring-opening temperature is 222-267℃, indicating that the prepolymer has the conditions for curing into resin. For the DSC test results of the prepolymer of resin 3, please refer to [reference needed]. Figure 13 ,from Figure 13 It can be seen that the glass transition temperature (Tg) of the prepolymer of resin 3 is 153℃, and the ring-opening temperature is 200-227℃, indicating that the prepolymer has the conditions to be cured into resin.

[0087] For infrared spectral analysis of resins 1-4 prepolymers, please refer to the appendix. Figure 14 , Figure 14 From top to bottom, the images show the infrared spectra of prepolymers 1, 2, 3, and 4. The image shows the infrared spectra of these prepolymers. As can be seen from the figures, the wavelength range is 2920-2850 cm⁻¹. -1 The position represents the CH stretching vibration of benzocyclobutene, 1601 cm⁻¹. -1 This is the stretching vibration of benzocyclobutene, 1453 cm⁻¹ -1 This is the stretching vibration of the four-membered ring in benzocyclobutene, 1377 cm⁻¹. -1 This is the out-of-plane stretching vibration of the CH group in the four-membered ring of benzocyclobutene; 907 cm⁻¹ -1 The position represents the out-of-plane stretching vibration of the alkene bond CH, 756-807 cm⁻¹. -1 It is a bending vibration.

Claims

1. A resin for high-frequency high-speed copper-clad plates, characterized by comprising: The structural formula of the resin is: R1 is a group containing a benzocyclobutene structure; R2 is hydrogen, an alkyl group, a hydroxyl group or an alkoxy group; 1 < n < 10000; the monomer structure of R1 before polymerization is one of the following I-III: R is hydrogen, an alkyl group, an alkoxy group, halogen or an amino group.

2. The polymerization method of resin for high-frequency high-speed copper-clad plate according to claim 1, characterized by, The polymerization method is: first, a prepolymer is synthesized, then the prepolymer is heated to 190-250 DEG C under nitrogen protection, and is kept for 1-3 h to obtain a completely cured resin.

3. The polymerization method of resin for high-frequency high-speed copper-clad plate according to claim 2, characterized in that, The synthesis method of the prepolymer is: unsaturated resin and specific monomers are dissolved in an organic solvent according to the required proportion, an initiator is added, and stirring is carried out to polymerize for 3-24 h to obtain the prepolymer, wherein the temperature is raised to 60-190 DEG C. The unsaturated resin is 1,2-polybutadiene or 1,2-polyisoprene; the specific monomer is a benzocyclobutene monomer.

4. The polymerization method of resin for high-frequency high-speed copper-clad plate according to claim 3, characterized by: The organic solvent is one of acetonitrile, tetrahydrofuran, toluene, xylene, trimethylbenzene, decaline and N,N'-dimethylformamide.

5. The polymerization method of resin for high-frequency high-speed copper-clad plate according to claim 3, characterized by: The initiator is one of di-tert-butyl peroxide isopropyl benzene, methyl ethyl ketone peroxide, azobis isobutyronitrile, ammonium persulfate and cyclohexanone peroxide.

6. The polymerization method of resin for high-frequency high-speed copper-clad plate according to claim 3, characterized in that: The mass ratio of the unsaturated resin and the specific monomer is (1-10):0.5.

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