Low-expansion bismaleimide-triazine resin composition / silicon dioxide composite substrate and preparation method thereof

Abstract

The invention discloses a bismaleimide-triazine resin (BT)-based high-frequency composite dielectric substrate suitable for the field of microwave substrates and a preparation method of the bismaleimide-triazine resin (BT)-based high-frequency composite dielectric substrate. According to the substrate, a bismaleimide-triazine resin composition is used as matrix resin, spherical silicon dioxide with a low dielectric constant is used as a filling material, and the composite substrate with the low dielectric constant, the low dielectric loss and the low thermal expansion coefficient is obtained. Meanwhile, the problem that the original thermal conductivity of the BT resin is poor is also improved. The raw materials selected by the method are easy to obtain, the preparation process is simple and controllable, the preparation process is low in energy consumption and short in time consumption, and the method can be applied to the high-speed and high-frequency field and has wide application prospects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high-frequency copper-clad plates for microwave circuits, and particularly relates to a preparation method of a low-expansion bismaleimide-triazine resin composition / silica composite substrate. BACKGROUND

[0002] With the rapid development of high-frequency electronic technologies such as 5G communication, millimeter wave radar, satellite communication, electronic devices are continuously evolving towards high speed, high frequency, miniaturization and integration, which puts forward more stringent requirements on the performance of printed circuit board (PCB) substrate materials. In the field of microwave high frequency (usually referring to the scenario with a frequency reaching GHz), signal transmission loss, thermal stability and dimensional stability become key factors affecting device performance, and traditional substrate materials have been difficult to meet the technical requirements. Currently, the commonly used materials for PCB substrates include epoxy resin-based composite materials (such as FR-4), polytetrafluoroethylene (PTFE), cyanate ester (CE) and bismaleimide-triazine resin (BT resin) and the like. Among them, the traditional epoxy resin substrate has a relatively large viscosity and a relatively large loss, which is difficult to meet the demand for high frequency and high speed of signal transmission; the polytetrafluoroethylene-based substrate has excellent high-frequency dielectric properties, but the processing technology is complex, the processing temperature is relatively high, and it contains F element which pollutes the environment. Therefore, the BT resin with excellent high-temperature resistance (glass transition temperature T g Generally higher than 200℃), good mechanical properties and low thermal expansion coefficient has attracted widespread attention in the high-frequency field. However, the problems of relatively high dielectric loss (tan δ) and relatively large thermal expansion coefficient (CTE) and low thermal conductivity coefficient limit its further development and application.

[0003] Currently, the commonly used improvement methods mainly include cross-linking modification of the BT resin matrix by preparing a multi-component composite resin system, and further optimization of the dielectric properties of the composite substrate by adding functional fillers with low dielectric constant and good filling properties. In addition, Chinese invention patents “Resin composition and preparation method thereof, prepreg, laminated board and printed circuit board” (application number CN202411916845.5) and “Allyl compound and preparation method thereof, bismaleimide resin composition and application thereof” (application number CN202411875353.6) disclose the preparation method of a BT-based composite substrate filled with glass fibers, which effectively reduces the thermal expansion coefficient. However, the composite substrate prepared by the above methods has a relatively high dielectric constant (>4@10GHz) and a relatively high dielectric loss (>0.005@10GHz), which is limited in the application in the field of high-speed electronic information.

[0004] Therefore, developing a BT-based composite substrate with low dielectric constant, low dielectric loss, good thermal conductivity, good matching with copper foil (CTE≈17ppm / ℃), and simplified preparation process and reduced production cost has become a key technical breakthrough to meet the development needs of high-frequency PCB field, and has important significance for promoting the progress of high-end electronic equipment such as 5G / 6G communication and new generation radar system. SUMMARY

[0005] The present application is directed to the problems existing in the background art, and proposes a preparation method of a low-expansion bismaleimide-triazine resin composition / silica composite substrate. The present application uses spherical silica with low dielectric constant and excellent filling performance as a filler, and uses a bismaleimide-triazine resin composition as a matrix resin. The prepared composite substrate has the characteristics of low dielectric constant, low dielectric loss and low thermal expansion coefficient, and further optimizes the thermal conductivity of the bismaleimide-triazine resin composite substrate. In addition, the preparation process is simple and easy to operate, the cost is low, and it is convenient to realize industrialized production.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows

[0007] A low-expansion bismaleimide-triazine resin composition / silica composite substrate, characterized in that the components of the composite substrate and the weight parts of each component in the composite substrate are as follows:

[0008] Bismaleimide resin: 10-20 parts

[0009] Triazine resin: 5-10 parts

[0010] Polyphenyl ether resin: 2-6 parts

[0011] Silica filler: 60-80 parts

[0012] Silane coupling agent: 1-3 parts

[0013] Modifier: 1-3 parts

[0014] Among them, the silica filler is spherical silica with a particle size of 5-10 microns and a dielectric constant of 3.7-4.5.

[0015] Further, the preparation method of the low-expansion bismaleimide-triazine resin composition / silica composite substrate comprises the following steps:

[0016] Step 1: a certain amount of silica and silane coupling agent are added into a mixed solvent of anhydrous ethanol and deionized water, the mass ratio of which is 1:2, and stirred until mixed uniformly; then the pH value of the mixed solution is adjusted to 3-5 with acetic acid, and after stirring at 60-80°C for 90-120 minutes, it is dried in an oven at 100-120°C; the modified silica powder is obtained after sieving through a 60-120 mesh sieve.

[0017] Step 2: a certain amount of bismaleimide resin and modifier are respectively dissolved in an organic solvent, and stirred at 100-140°C for 3-4h to obtain a bismaleimide resin prepolymer.

[0018] Step 3: a certain amount of bismaleimide resin prepolymer, triazine resin, and polyphenyl ether resin are respectively dissolved in an organic solvent, and after stirring until the resin system is completely dissolved and mixed uniformly, the modified silica filler is added to the system, and reacted for 6-8h to obtain a sizing agent.

[0019] Step 4: the sizing agent obtained in Step 2 is poured into a rectangular mold to form a film, and the film thickness is 1-3mm; the film is dried to remove the solvent, and the oven temperature is set to 100-120°C, and the holding time is 1-3h.

[0020] Step 5: the film obtained in Step 3 is cut and then covered with copper foil on both sides for hot pressing; the hot pressing temperature is 200-250°C, the hot pressing time is 1-3h, and the hot pressing pressure is 5-10MPa; the composite substrate is obtained after hot pressing is completed.

[0021] Preferably, the silane coupling agent is one or two of vinyltrimethoxysilane, phenyltrimethoxysilane, aminopropyltriethoxysilane, glycidyl ether oxypropyltrimethoxysilane, and 3-methacryloyloxypropyltrimethoxysilane.

[0022] Preferably, the bismaleimide resin includes one or more of biphenyl type bismaleimide resin, bis(3-ethyl-5-methyl-4-maleimide phenyl)methane, and polyphenylmethane maleimide.

[0023] Preferably, the modifier further includes one or more of diallyl bisphenol A, diallyl bisphenol F, diallyl bisphenol S, and bisphenol A diallyl ether.

[0024] Preferably, the cyanate ester resin includes one or more of bisphenol A type cyanate ester resin, bisphenol F type cyanate ester resin, bisphenol E type cyanate ester resin, bisphenol M type cyanate ester resin, phenolic type cyanate ester resin, biphenyl type cyanate ester resin, naphthalene type cyanate ester resin, bisphenol S type cyanate ester resin, and dicyclopentadiene bisphenol type cyanate ester resin.

[0025] Preferably, the polyphenyl ether resin is a cross-linkable reactive polyphenyl ether resin, and the reactive group is one or more of hydroxyl, allyl, vinyl and acrylic groups.

[0026] Preferably, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, cyclohexane, butanone, toluene and xylene.

[0027] Further, the mass fraction of the bismaleimide resin, the triazine resin, the polyphenyl ether resin, the modifier, the silica filler and the silane coupling agent is:

[0028] The bismaleimide resin is 10-20 parts

[0029] The triazine resin is 5-10 parts

[0030] The polyphenyl ether resin is 2-6 parts

[0031] The silica filler is 60-80 parts;

[0032] The silane coupling agent is 1-3 parts;

[0033] The modifier is 1-3 parts;

[0034] Compared with the prior art, the present application has the following advantages

[0035] 1. The bismaleimide-triazine resin composition selected by the present application is first modified by the diallyl bisphenol A modifier to pre-polymerize the bismaleimide, which greatly solves the problem of bismaleimide monomer precipitation. Secondly, low molecular weight double bond modified polyphenyl ether is blended, which can form an interpenetrating cross-linked network during hot pressing, and endow the composite substrate with excellent dielectric properties.

[0036] 2. The spherical silica filler selected by the present application and the resin composition substrate raw material are easy to obtain, low in cost, simple in preparation process, easy to industrialize production, and meet the concept of green electronic chemistry and clean production preparation.

[0037] 3. The low-expansion bismaleimide-triazine resin composition / silica composite substrate obtained by the present application has the advantages of low dielectric constant (3.25@10GHz), low dielectric loss (0.0028@10GHz), low thermal expansion coefficient (18.66ppm / ℃) and good thermal conductivity (0.613W / (m·K)) at high frequency, and has good application prospect in the field of high-speed composite substrates. DETAILED DESCRIPTION

[0038] The technical solutions of the present application are described in detail below through specific examples, however, the examples are only typical and not limiting.

[0039] Example 1

[0040] Step 1: 100 g of silica and 3 g of silane coupling agent were dissolved in 500 g of a mixed solvent of anhydrous ethanol / deionized water, stirred at room temperature until mixed uniformly, the pH of the system was adjusted to 4 with glacial acetic acid, and stirred for 2 h, then dried in a 100℃ air drying oven, and sieved through a 120 mesh sieve to obtain modified silica powder.

[0041] Step 2: 10 g of bismaleimide resin and 2 g of diallyl bisphenol A modifier were weighed separately and dissolved in xylene solvent, and stirred at 120℃ for 4 h to obtain a bismaleimide prepolymer.

[0042] Step 3: 3 g of polyphenyl ether resin and 5 g of triazine resin were weighed separately and dissolved in the bismaleimide prepolymer solution obtained in step 2, and after the resin system was completely dissolved, 30 g of modified silica filler was added to the system, and reacted for 6-8 h to obtain a sizing material.

[0043] Step 4: The sizing material obtained in step 3 was poured into a rectangular mold to form a film, and the film thickness was 1 mm, and the film was dried to remove the solvent.

[0044] Step 5: The film obtained in step 4 was cut and copper foil was attached to both sides for hot pressing; the hot pressing temperature was 240℃, the hot pressing time was 2 h, and the hot pressing pressure was 8 MPa, and after hot pressing, the composite substrate was obtained. The surface copper foil of the prepared composite substrate was etched off, and cut into 50mm×30mm and 3mm×3mm square pieces and a diameter of 12.7mm round pieces for testing of microwave dielectric properties, thermal expansion coefficient and thermal conductivity.

[0045] Examples 2-5

[0046] Examples 2-5 differ from Example 1 in that the mass of modified silica added in step 2 is adjusted to 37.1 g, 46.7 g, 60 g and 80 g respectively; accordingly, the mass of the solvent xylene is also increased appropriately in each example.

[0047] Table 1 Properties of the composite substrates prepared in each example

[0048]

[0049] The inventors tested the dielectric properties, thermal expansion coefficient and thermal conductivity of the prepared composite substrates, as shown in Table 1. The results show that each example has a low dielectric constant, low dielectric loss and good thermal conductivity, with a minimum dielectric loss of 0.0028, a minimum thermal expansion coefficient of 12.98 ppm / ℃, and a maximum thermal conductivity of 0.616 (W / (m·K)), making it suitable for use in the field of high-frequency high-speed composite substrates.

[0050] The above description of the embodiments is made for the purpose of illustration only, and does not limit the embodiments. Based on the above embodiments, other different forms of changes can be made by those skilled in the art. Therefore, the present application is not limited to the above specific embodiments, and all improvements and modifications that do not depart from the scope of the present application should be included in the protection scope of the present application, which is defined by the claims.

Claims

1. A low-expansion bismaleimide-triazine resin composition / silica composite substrate, characterized in that, The components of the composite substrate and the weight percentage of each component in the composite substrate are as follows: Bismaleimide resin: 10-20 parts Triazine resin: 5-10 parts Polyphenylene ether resin: 2-6 parts Silica filler: 60-80 parts; Silane coupling agent: 1-3 parts; Modifier: 1-3 parts.

2. The low-expansion bismaleimide-triazine resin composition / silica composite substrate according to claim 1, characterized in that, The spherical silica filler has a particle size of 5–10 micrometers and a dielectric constant of 3.7–4.

5.

3. The low-expansion bismaleimide-triazine resin composition / silica composite substrate according to claim 1, characterized in that, The preparation method of the low-expansion bismaleimide-triazine resin composition / silica composite substrate includes the following specific steps: Step 1: Add an appropriate amount of silica and silane coupling agent to a mixed solvent of anhydrous ethanol / deionized water, and stir until homogeneous. The mass ratio of anhydrous ethanol to deionized water is 1:

2. Then, adjust the pH of the mixture to 3-5 using acetic acid. Stir and mix at 60-80℃ for 90-120 minutes, and then dry in an oven at 100-120℃. After sieving through a 60-120 mesh sieve, modified silica powder is obtained. Step 2: Take appropriate amounts of bismaleimide resin and modifier respectively and dissolve them in an organic solvent. Stir at 100-140℃ for 3-4 hours to obtain bismaleimide resin prepolymer. Step 3: Take appropriate amounts of bismaleimide resin prepolymer, triazine resin, and polyphenylene ether resin respectively and dissolve them in an organic solvent. Stir until the resin system is completely dissolved and mixed evenly. Then add the modified silica filler to the system and react for 6-8 hours to obtain the adhesive. Step 4: Pour the adhesive obtained in Step 2 into a rectangular mold to form a film with a thickness of 1-3 mm; dry the film to remove the solvent, set the oven temperature to 100℃-120℃, and keep it warm for 1-3 hours. Step 5: After cutting the film obtained in Step 3, copper foil is applied to both sides and hot-pressed. The hot-pressing temperature is 200-250℃, the hot-pressing time is 1-3h, and the hot-pressing pressure is 5-10MPa. After hot-pressing, the composite substrate is obtained.

4. The low-expansion bismaleimide-triazine resin composition / silica composite substrate according to claim 3, characterized in that, The silane coupling agent is one or two of vinyltrimethoxysilane, phenyltrimethoxysilane, aminopropyltriethoxysilane, glycidyl etheroxypropyltrimethoxysilane, and 3-methacryloyloxypropyltrimethoxysilane.

5. The method for preparing the low-expansion bismaleimide-triazine resin composition / silica composite substrate according to claim 3, characterized in that, The bismaleimide resin includes one or more of biphenyl-type bismaleimide resin, bis(3-ethyl-5-methyl-4-maleimidebenzene)methane, and polyphenylene maleimide.

6. The method for preparing the low-expansion bismaleimide-triazine resin composition / silica composite substrate according to claim 3, characterized in that, The modifier also includes one or more of diallyl bisphenol A, diallyl bisphenol F, diallyl bisphenol S, and bisphenol A diallyl ether.

7. The method for preparing the low-expansion bismaleimide-triazine resin composition / silica composite substrate according to claim 3, characterized in that, The cyanate resin includes one or more of the following: bisphenol A type cyanate resin, bisphenol F type cyanate resin, bisphenol E type cyanate resin, bisphenol M type cyanate resin, phenolic type cyanate resin, biphenyl type cyanate resin, naphthalene type cyanate resin, bisphenol S type cyanate resin, and dicyclopentadiene bisphenol type cyanate resin.

8. The method for preparing the low-expansion bismaleimide-triazine resin composition / silica composite substrate according to claim 3, characterized in that, The polyphenylene ether resin is a crosslinkable reactive polyphenylene ether resin, and the reactive groups are one or more of hydroxyl, allyl, vinyl and acrylic groups.

9. The method for preparing the low-expansion bismaleimide-triazine resin composition / silica composite substrate according to claim 3, characterized in that, The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, cyclohexane, butanone, toluene, and xylene.

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