Modified silica powder enhanced copper-clad plate and preparation method thereof

Abstract

The invention relates to the technical field of electronic materials, in particular to a modified silica powder enhanced copper-clad plate and a preparation method thereof. Comprising a base material layer, a copper foil layer and a reinforced composite layer arranged between the base material layer and the copper foil layer, the reinforced composite layer comprises surface modified silica powder and a resin composition, the surface modified silica powder is subjected to double modification treatment by an amino silane coupling agent and a titanate coupling agent, and the surface hydroxyl content is less than or equal to 0.8 mmol / g. According to the modified silica powder enhanced copper-clad plate and the preparation method thereof, silica powder is doubly modified through amino silane and a titanate coupling agent, the surface hydroxyl content is remarkably reduced, and the compactness and thermal mechanical performance of a resin composite layer are optimized in combination with the bimodal distribution particle size design.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic materials, and particularly to a modified silica powder reinforced copper clad laminate and a preparation method thereof. Background Art

[0002] As the core substrate of printed circuit boards (PCBs), copper clad laminates (CCLs) directly affect the reliability of electronic devices and the signal transmission efficiency. Traditional CCLs usually consist of a substrate layer, a reinforcing layer, and a copper foil layer, where the reinforcing layer is mostly composed of a glass fiber cloth or a composite of ordinary inorganic fillers (such as silica powder) and resin.

[0003] However, the following problems still exist in the prior art: (1) The surface hydroxyl content of ordinary silica powder is relatively high, and the binding force with the resin matrix is weak, which easily leads to uneven dispersion of the filler and stress concentration at the interface, thereby reducing the mechanical strength and thermal stability of the copper clad laminate; (2) It is difficult for silica powder with a single particle size distribution to optimize the coefficient of thermal expansion of the resin composite layer, and delamination or warping is likely to occur due to thermal stress in a high-temperature environment; (3) Although traditional flame retardants (such as halogen-containing compounds) can improve the flame retardancy, they may deteriorate the dielectric properties and do not meet the environmental protection requirements. Summary of the Invention

[0004] The present invention provides a modified silica powder reinforced copper clad laminate and a preparation method thereof. By double-modifying silica powder with an amino silane and a titanate coupling agent, the surface hydroxyl content is significantly reduced, and combined with the particle size design of bimodal distribution, the compactness and thermo-mechanical properties of the resin composite layer are optimized.

[0005] The technical solution adopted by the present invention is as follows: A modified silica powder reinforced copper clad laminate includes a substrate layer, a copper foil layer, and a reinforcing composite layer disposed therebetween. The reinforcing composite layer contains surface-modified silica powder and a resin composition. The surface-modified silica powder is double-modified with an amino silane coupling agent and a titanate coupling agent, and the surface hydroxyl content is ≤0.8 mmol / g.

[0006] As a further improvement of the present invention, the particle size of the surface-modified silica powder shows a bimodal distribution, where 60-75% of the particles have a D50 of 2-5 μm, and 25-40% of the particles have a D50 of 0.5-1.2 μm.

[0007] As a further improvement of the present invention, the bimodal distribution particles are achieved by a classification screening process, and the surface of the coarse particles has a nano-scale pit structure with a pit depth of 50-200 nm.

[0008] As a further improvement of the present invention, the resin composition consists of the following parts by weight: 40 - 60 parts of epoxy resin, 15 - 25 parts of polyphenylene ether resin, 8 - 12 parts of phosphorus-containing flame retardant, and the filling amount of the modified silica powder is 45 - 65% of the total weight of the resin composition.

[0009] As a further improvement of the present invention, the molecular chain ends of the polyphenylene ether resin are grafted with vinyl benzyl structures, and the grafting rate is 1.2 - 1.8 per molecular chain.

[0010] A preparation method of a modified silica powder-reinforced copper clad laminate includes the following steps:

[0011] S1: Perform plasma pretreatment on the silica powder, with a treatment power of 300 - 500 W and a treatment time of 5 - 15 min;

[0012] S2: Use the gradient impregnation method for coupling agent modification: first impregnate in an amino silane solution with pH = 4.5 - 5.5 for 30 - 60 min, and then perform secondary impregnation in a titanate / ethanol solution;

[0013] S3: Mix the modified silica powder and the resin composition in a double planetary mixer, controlling the vacuum degree ≤ -0.08 MPa and the temperature at 85 - 95 °C;

[0014] S4: Adopt a segmented hot pressing process: pre-cure at 120 - 130 °C for 20 - 40 min in the first stage, and final-cure at 170 - 185 °C for 60 - 90 min in the second stage.

[0015] As a further improvement of the present invention, in the step S1, argon is used as the working gas for plasma pretreatment, and the gas flow rate is 20 - 40 L / min.

[0016] As a further improvement of the present invention, in the step S2, after secondary impregnation, microwave-assisted drying is adopted, with a microwave power of 300 - 500 W, a drying time of 8 - 15 min, and controlling the final water content ≤ 0.3 wt%.

[0017] As a further improvement of the present invention, in the step S3, an asymmetric stirring paddle is used during the stirring process, the main paddle rotates at 150 - 200 rpm, the auxiliary paddle rotates at 800 - 1200 rpm, and the rotation speed ratio changes periodically according to a sine wave form.

[0018] As a further improvement of the present invention, in the step S4, an alternating pressure field is applied in the second stage of the segmented hot pressing process, and the pressure fluctuates within the range of 5 - 8 MPa at a frequency of 0.5 - 1 Hz.

[0019] Advantages of the present invention: (1) Through dual modification with amino silane and titanate coupling agent, the hydroxyl group content on the surface of silica powder is reduced to ≤0.8 mmol / g, effectively enhancing the bonding force with the resin matrix, increasing the flexural strength of the copper clad laminate by more than 30%, and the heat distortion temperature reaching 220°C. At the same time, combined with the asymmetric stirring process and the segmented hot pressing alternating pressure field, the dispersion uniformity of the filler is improved, the porosity is lower than 0.1%, and the product uniformity and impact resistance are significantly optimized.

[0020] (2) The present invention uses modified silica powder with bimodal distribution (cooperatively filled with particles with D50 of 2 - 5 μm and 0.5 - 1.2 μm), reducing the coefficient of thermal expansion of the resin composite layer to 12 - 15 ppm / °C, which is highly matched with the coefficient of thermal expansion of copper foil (about 17 ppm / °C). After high-temperature thermal cycle testing (150°C / 100 times), there is no delamination phenomenon, and the warpage degree is reduced by 40%, greatly improving the reliability in high-temperature environments.

[0021] (3) The phosphorus-containing flame retardant (8 - 12 parts) and the polyphenylene ether resin grafted with vinyl benzyl at the end (grafting rate of 1.2 - 1.8 per molecular chain) in the present invention act synergistically, achieving UL94 V-0 level flame retardancy while having a dielectric constant (Dk) ≤ 3.5 @ 1 GHz and a dielectric loss (Df) ≤ 0.005 @ 1 GHz, meeting the stringent requirements of high-frequency scenarios such as 5G communication and high-speed circuits. Specific embodiments

[0022] In order to make the technical problems, technical solutions and advantages to be solved by the present application more clear and understandable, the following further details the present application in combination with embodiments. It should be understood that the embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] The present invention provides a modified silica powder reinforced copper clad laminate, which includes a substrate layer, a copper foil layer, and a reinforcing composite layer disposed therebetween. The reinforcing composite layer contains surface-modified silica powder and a resin composition. The surface-modified silica powder is treated by dual modification with amino silane coupling agent and titanate coupling agent, and the surface hydroxyl group content is ≤0.8 mmol / g.

[0024] In the present invention, the particle size of the surface-modified silica powder shows a bimodal distribution, among which 60 - 75% of the particles have D50 of 2 - 5 μm, and 25 - 40% of the particles have D50 of 0.5 - 1.2 μm. The bimodal distribution particles are realized by a classification screening process, and the surface of the coarse particles has a nano-scale pit structure with a pit depth of 50 - 200 nm.

[0025] In the present invention, the resin composition consists of the following components by weight: 40 - 60 parts of epoxy resin, 15 - 25 parts of polyphenylene ether resin, 8 - 12 parts of phosphorus-containing flame retardant, and the filling amount of modified silica powder is 45 - 65% of the total weight of the resin composition. The molecular chain end of the polyphenylene ether resin is grafted with a vinyl benzyl structure, and the grafting rate is 1.2 - 1.8 per molecular chain.

[0026] A preparation method of a modified silica powder-reinforced copper clad laminate includes the following steps:

[0027] S1: Perform plasma pretreatment on the silica powder, with a treatment power of 300 - 500 W, a treatment time of 5 - 15 min. Argon is used as the working gas for the plasma pretreatment, and the gas flow rate is 20 - 40 L / min;

[0028] S2: Use the gradient impregnation method for coupling agent modification: First, impregnate in an amino silane solution with pH = 4.5 - 5.5 for 30 - 60 min, then perform secondary impregnation in a titanate / ethanol solution. After secondary impregnation, use microwave-assisted drying, with a microwave power of 300 - 500 W and a drying time of 8 - 15 min, and control the final water content ≤ 0.3 wt%;

[0029] S3: Mix the modified silica powder and the resin composition in a double planetary mixer, control the vacuum degree ≤ -0.08 MPa, the temperature is 85 - 95 °C. During the mixing process, use an asymmetric mixing paddle, the main paddle speed is 150 - 200 rpm, the auxiliary paddle speed is 800 - 1200 rpm, and the speed ratio changes periodically according to a sine wave form;

[0030] S4: Adopt a segmented hot pressing process: In the first stage, pre-cure at 120 - 130 °C for 20 - 40 min, and in the second stage, final-cure at 170 - 185 °C for 60 - 90 min. An alternating pressure field is applied in the second stage of the segmented hot pressing process, and the pressure fluctuates within the range of 5 - 8 MPa at a frequency of 0.5 - 1 Hz.

[0031] Example 1:

[0032] Step S1: Take 1000 g of silica powder, use argon as the working gas (flow rate 30 L / min), perform plasma pretreatment, with a power of 400 W and a time of 10 min.

[0033] Step S2: Immerse the pretreated silica powder in an amino silane solution with pH = 5.0 for 45 min, and then transfer it to a titanate / ethanol solution (mass ratio 1:9) for secondary impregnation for 30 min. The microwave-assisted drying power is 400 W and the time is 10 min, and the final water content is 0.25 wt%.

[0034] Step S3: According to the weight ratio, 50 parts of epoxy resin, 20 parts of polyphenylene ether resin, and 10 parts of phosphorus-containing flame retardant are added, and modified silica powder (filling amount 55wt%) is added and mixed in a double planetary mixer. The vacuum degree is -0.09MPa, the temperature is 90°C, the main paddle speed is 180rpm, the auxiliary paddle speed is 1000rpm, and the speed ratio changes according to the sine wave period.

[0035] Step S4: Segmented hot pressing process: The first stage is pre-cured at 125°C for 30min, and the second stage is finally cured at 180°C for 75min. An alternating pressure field is applied during the final curing stage (pressure 6MPa, frequency 0.8Hz).

[0036] Example 2:

[0037] Step S1: 1000g of silica powder, argon flow rate 40L / min, plasma pretreatment power 500W, time 5min.

[0038] Step S2: The pH of the amino silane solution is 4.5, and the impregnation time is 60min; the titanate / ethanol solution is impregnated for a second time for 20min. The microwave drying power is 500W, the time is 8min, and the water content is 0.2wt%.

[0039] Step S3: Resin composition ratio: 60 parts of epoxy resin, 15 parts of polyphenylene ether resin, 12 parts of phosphorus-containing flame retardant, and the filling amount of modified silica powder is 65wt%. The main paddle speed is 200rpm, the auxiliary paddle speed is 1200rpm, and the temperature is 95°C.

[0040] Step S4: Segmented hot pressing: The first stage is pre-cured at 130°C for 20min, and the second stage is finally cured at 185°C for 60min. The alternating pressure field pressure is 8MPa, and the frequency is 1Hz.

[0041] Example 3:

[0042] Step S1: 1000g of silica powder, argon flow rate 20L / min, plasma pretreatment power 300W, time 15min.

[0043] Step S2: The pH of the amino silane solution is 5.5, and the impregnation time is 30min; the titanate / ethanol solution is impregnated for a second time for 40min. The microwave drying power is 300W, the time is 15min, and the water content is 0.3wt%.

[0044] Step S3: Resin composition ratio: 40 parts of epoxy resin, 25 parts of polyphenylene ether resin, 8 parts of phosphorus-containing flame retardant, and the filling amount of modified silica powder is 45wt%. The main paddle speed is 150rpm, the auxiliary paddle speed is 800rpm, and the temperature is 85°C.

[0045] Step S4: Segmented hot pressing: In the first stage, pre-cure at 120°C for 40 min, in the second stage, final cure at 170°C for 90 min, with an alternating pressure field pressure of 5 MPa and a frequency of 0.5 Hz.

[0046] The comparison table of product data and performance indicators is as follows.

[0047]

[0048]

[0049] As can be seen from the above table, Example 1 has the best comprehensive performance, with a flexural strength of 325.6 MPa, good matching of the thermal expansion coefficient with copper foil (13.54 ppm / °C), and achieves V-0 level flame retardancy; Example 2 has the highest heat distortion temperature, reaching 233.8°C, showing excellent thermal stability; while Example 3, although slightly inferior to the former two in some indicators, has stable dielectric properties and meets the application requirements of high-frequency scenarios. Generally speaking, the modified silica powder reinforced copper clad laminate and its preparation method of the present invention significantly improve the comprehensive performance of the copper clad laminate through optimized material ratios and preparation processes, and have broad application prospects.

[0050] In summary, a modified silica powder reinforced copper clad laminate and its preparation method of the present invention, through innovative dual modification technology and bimodal particle size design, not only significantly improve the mechanical strength, thermal stability and flame retardancy of the copper clad laminate, but also optimize the dielectric properties and the matching of the thermal expansion coefficient, providing an ideal substrate solution for high-frequency and high-speed circuit applications. The preparation method has a simple process, is easy to scale up production, and has high practical value and application prospects.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modified silicon powder reinforced copper clad laminate, characterized in that: The invention comprises a substrate layer, a copper foil layer and a reinforced composite layer arranged therebetween, wherein the reinforced composite layer comprises surface-modified silicon micropowder and a resin composition, wherein the surface-modified silicon micropowder is double-modified by an aminosilane coupling agent and a titanate coupling agent, and the surface hydroxyl content is ≤0.8 mmol / g.

2. The modified silicon powder reinforced copper clad laminate according to claim 1, characterized in that: The particle size of the surface modified silicon micropowder presents a bimodal distribution, wherein particles with a D50 of 2-5 μm account for 60-75%, and particles with a D50 of 0.5-1.2 μm account for 25-40%.

3. The modified silicon powder reinforced copper clad laminate according to claim 2, characterized in that: The bimodal distribution particles are obtained by a graded screening process, wherein the surface of the coarse particles has a nanometer-scale pit structure with a pit depth of 50-200 nm.

4. The modified silicon powder reinforced copper clad laminate according to claim 1, characterized in that: The resin composition is composed of the following parts by weight: 40-60 parts of epoxy resin, 15-25 parts of polyphenylene ether resin, and 8-12 parts of phosphorus-containing flame retardant. The filling amount of the modified silicon micropowder is 45-65% of the total weight of the resin composition.

5. The modified silicon powder reinforced copper clad laminate according to claim 4, characterized in that: The molecular chain end of the polyphenylene ether resin is grafted with a vinyl benzyl structure, and the grafting rate is 1.2-1.8 per molecular chain.

6. A method for preparing a modified silicon powder reinforced copper clad laminate, characterized in that: The following steps are involved: S1: Plasma pretreatment of silicon powder, with a processing power of 300-500W and a processing time of 5-15min; S2: Coupling agent modification was performed using a gradient impregnation method: first, the mixture was impregnated in an aminosilane solution at pH = 4.5-5.5 for 30-60 min, and then impregnated in a titanate / ethanol solution for a second time; S3: Mix the modified silicon powder and the resin composition in a double planetary mixer, control the vacuum degree to ≤-0.08MPa, and the temperature to 85-95°C; S4: adopts segmented hot pressing process: the first stage is pre-curing at 120-130℃ for 20-40min, and the second stage is final curing at 170-185℃ for 60-90min.

7. The method for preparing a modified silicon powder reinforced copper clad laminate according to claim 6, characterized in that: In the step S1, argon is used as the working gas for plasma pretreatment, and the gas flow rate is 20-40 L / min.

8. The method for preparing a modified silicon powder reinforced copper clad laminate according to claim 6, characterized in that: In the step S2, microwave-assisted drying is adopted after the secondary impregnation, the microwave power is 300-500 W, the drying time is 8-15 min, and the final water content is controlled to be ≤0.3 wt%.

9. The method for preparing a modified silicon powder reinforced copper clad laminate according to claim 6, characterized in that: In step S3, an asymmetric stirring paddle is used in the stirring process, the main paddle speed is 150-200 rpm, the auxiliary paddle speed is 800-1200 rpm, and the speed ratio changes periodically according to a sinusoidal waveform.

10. The method for preparing a modified silicon powder reinforced copper clad laminate according to claim 6, characterized in that: In step S4, an alternating pressure field is applied in the second stage of the segmented hot pressing process, and the pressure fluctuates within the range of 5-8 MPa at a frequency of 0.5-1 Hz.

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