Alkali-resistant spherical silica slurry for packaging substrate and preparation method thereof

Abstract

The application discloses an alkali-resistant spherical silica slurry for packaging substrates and a preparation method thereof. The method comprises the following steps: firstly, compounding submicron spherical silica and micron spherical silica; secondly, wetly modifying the compounded spherical silica by using a silane coupling agent; thirdly, secondly modifying the wetly modified spherical silica by using a non-polar short-chain silane coupling agent; and finally, dispersing the modified spherical silica in an organic solvent, and obtaining the spherical silica slurry through grading. The spherical silica slurry prepared by the method has good stability, reasonable product particle size distribution, and uniform modifier coating, and has good alkali resistance, good fluidity and low melting viscosity when applied to packaging substrates.

Description

Technical Field

[0001] This invention belongs to the field of inorganic filler technology, and relates to an alkali-resistant spherical silica slurry for packaging substrates and its preparation method. Background Technology

[0002] The packaging substrate, also known as the IC substrate, is a crucial material used in IC packaging to connect the chip to the PCB motherboard. It has largely replaced traditional lead frames in mid-to-high-end packaging applications. The main functions of the IC substrate include providing protection, support, and heat dissipation for the chip. While similar in structure and function to PCBs and evolved from HDI boards, the technological threshold for IC substrates is significantly higher than that of HDI and ordinary PCBs. They are characterized by high density, high precision, high pin count, high performance, miniaturization, and thinness, and require higher specifications in various technical parameters such as line width / spacing.

[0003] The packaging substrate has high requirements for CTE (Chemical Equilibrium Tolerance). In addition to high fluidity, it also requires good bonding between the filler and resin, good alkali resistance, and low surface roughness after Desmearing. When the alkali resistance is poor, the surface roughness after Desmearing is large, which may pose a risk to the long-term reliability of interlayer insulation.

[0004] Chinese patent CN106700132B discloses a silica slurry composition, which uses nano-sized silica to coat the surface of silica micropowder and disperse it in an organic solvent to obtain a silica slurry composition. This product is used in laminates and has good dispersibility and flowability. However, the addition of nano-spherical silica cannot improve its alkali resistance.

[0005] Chinese patent CN109021292B discloses a slurry composition. The silica slurry composition is prepared by coating a weakly polar or non-polar monomer onto the surface of silica using a plasma modification method and then dispersing it in an organic solvent. The composition has good dispersibility, flowability and dielectric properties. At the same time, due to the uniform coating of the modifier, it has good sedimentation stability. However, the plasma modification method used in this method is difficult to industrialize. Summary of the Invention

[0006] The purpose of this invention is to provide an alkali-resistant spherical silica paste for packaging substrates with good stability and its preparation method.

[0007] The technical solution for achieving the objective of this invention is as follows:

[0008] The specific steps for preparing alkali-resistant spherical silica paste for packaging substrates are as follows:

[0009] (1) Raw material compounding:

[0010] Set D50=0.3-0.8μm, D100≤5.0μm, SSA=4.0-12.0m 2 / g of submicron spherical silica with D50 = 1.0-3.0μm, D100 ≤ 5.0μm, and SSA = 0.5-4.0m 2 Micron-sized spherical silica ( / g) was mixed at a mass ratio of 1:3-3:1 to obtain D50 = 0.4-2.0μm, D100 ≤ 5.0μm, and SSA = 1.5-9.0μm. 2 / g of spherical silica A;

[0011] (2) Wet modification:

[0012] Spherical silica A and water are mixed evenly at a mass ratio of 3:7-6:4. After pre-dispersion, a submicron slurry is obtained. Then, a modifier is added, and the mixture is subjected to wet grinding for preliminary modification. The pre-modified slurry is then dried at 120-300℃ until the moisture content is ≤0.3%. After drying, the mixture is kept at 60-120℃. Finally, the material after heat preservation is depolymerized to a particle size consistent with that of spherical silica A to obtain wet-modified spherical silica B. The modifier is selected from epoxy, aniline, isocyanate, or urea-based silane coupling agents.

[0013] (3) Secondary modification:

[0014] Spherical silica B is modified twice using a nonpolar short-chain silane coupling agent to obtain spherical silica C after secondary modification. The short-chain silane coupling agent is a short-chain alkyl silane coupling agent or a silazane; (4) Slurrying:

[0015] Spherical silica C is pre-dispersed in an organic solvent under stirring, then dispersed in a disperser, and then classified to remove large particles to obtain spherical silica slurry. The organic solvent is acetone, butanone, methyl isobutyl ketone (MIBK), or cyclohexanone.

[0016] Preferably, in step (2), a sand mill is used for pre-dispersion, and the pre-dispersion temperature is 50-90℃.

[0017] Preferably, in step (2), the heat preservation time is 20-60 minutes.

[0018] Preferably, in step (2), an air jet mill is used for depolymerization, and the depolymerization pressure is ≥1.0MPa.

[0019] Preferably, in step (2), the mass ratio of the modifier to spherical silica A is 0.1-2.0:100.

[0020] Preferably, in step (2), the epoxy silane coupling agent is 3-glycidylpropyltrimethoxysilane, the aniline silane coupling agent is N-phenyl-3-aminopropyltrimethoxysilane, the isocyanate silane coupling agent is 3-isocyanate propyltriethoxysilane, and the ureosilane coupling agent is 3-ureapropyltriethoxysilane.

[0021] Preferably, in step (3), the short-chain alkylsilane is selected from methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, dimethyldimethoxysilane or trimethylmethoxysilane, and the silazane is hexamethyldisilazane or tetramethyldisilazane;

[0022] Preferably, in step (3), the mass ratio of the nonpolar short-chain silane coupling agent to the spherical silica B is 0.1-1.0:100.

[0023] Preferably, in step (3), the modification equipment is a high-speed mixer, the modification temperature is 80-150℃, and the modification time is 10-40min.

[0024] Preferably, in step (4), the mass ratio of spherical silica C to organic solvent is 25:75-50:50.

[0025] Preferably, in step (4), the disperser is a high-pressure homogenizer with a dispersion pressure of 10,000 psi-20,000 psi; the equipment used for grading is a wet vibrating screen with a screen aperture ≤10 μm.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The present invention uses micron-sized spherical silica with small specific surface area and narrow distribution in submicron spherical silica. Micron-sized spherical silica has a small specific surface area, resulting in less interfacial contact with resin during use. At the same time, the combination of large and small spheres can improve alkali resistance, and the surface roughness is low after Desmear treatment.

[0028] (2) This invention uses a polar silane coupling agent for wet modification, resulting in uniform coating. A second modification is then performed using short-chain silanes. The presence of polar groups improves the compatibility between the filler and the resin, while the presence of non-polar groups enhances the filler's dispersibility. Therefore, the filler exhibits good alkali resistance and low surface roughness after Desmear treatment. Furthermore, the synergistic effect of the silane coupling agent and short-chain silanes further improves the product's stability and flowability.

[0029] (3) The spherical silica slurry product prepared by the present invention has good stability. When applied to the packaging substrate, it has good alkali resistance and low surface roughness after Desmear treatment. At the same time, the production process is easy to control, the product has good stability, and it is suitable for mass production. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments.

[0031] The test methods for D50, D100, pH, TGA weight loss, viscosity, and flow time of silica powder in the following examples and comparative examples are as follows:

[0032] (1) D50 and D100 tests: The Beckman Coulter LS13320 laser particle size analyzer was used for testing.

[0033] (2) Sedimentation stability: Pour the slurry into a 100ml stoppered test tube to the 100ml mark, seal it, and store it at room temperature. After one month, observe the stratification of the slurry, record the height of the clear liquid in each stratification, and observe whether there is sedimentation at the bottom after inverting the tube. The less stratification and the less sedimentation at the bottom, the better the product stability.

[0034] (3) Melt viscosity test: The rheological curve of the prepreg resin powder used in the carrier board formulation is tested in the range of 80 to 190°C to determine the minimum melt viscosity (η). The lower the minimum melt viscosity, the better the flowability.

[0035] Example 1

[0036] (1) Raw material compounding

[0037] Set D50=0.50μm, D100=2.6μm, SSA=6.6m 2 / g of submicron spherical silica with D50 = 1.5μm, D100 = 2.2μm, and SSA = 2.6m 2 Micron-sized spherical silica particles of 1 g were mixed at a mass ratio of 1:1 to obtain particles with D50 = 0.93 μm, D100 = 2.6 μm, and SSA = 4.6 μm. 2 / g of spherical silica A;

[0038] (2) Wet modification

[0039] Spherical silica A and deionized water were mixed evenly at a mass ratio of 1:1 and then fed into a sand mill for pre-dispersion at a temperature controlled at 80℃. After uniform dispersion, a submicron slurry was obtained. Then, 0.6% of N-phenyl-3-aminopropyltrimethoxysilane KBM-573 (Shin-Etsu Chemical) was added, and the mixture was wet-milled for preliminary modification. The pre-modified slurry was then fed into a flash dryer for further drying modification at an inlet air temperature of 250℃ until the moisture content was ≤0.3%. After drying, the slurry was fed into a collector for heat preservation at 110℃ for 30 minutes to complete the secondary modification. The heat-preserved material was then depolymerized using an air jet mill at a pressure of 1.0 MPa to obtain wet-modified spherical silica B.

[0040] (3) Secondary modification

[0041] Spherical silica B was added to a high-speed mixer along with methyltrimethoxysilane KBM-13 (Shin-Etsu Chemical). The mixture was modified at 100°C for 20 minutes to obtain secondary modified spherical silica C. The mass ratio of methyltrimethoxysilane KBM-13 to spherical silica B was 0.3:100.

[0042] (4) Slurrying

[0043] Spherical silica C and organic solvent acetone were added to a mixing tank at a mass ratio of 7:3 for initial dispersion. Then, the mixture was further dispersed using a homogenizer under a pressure of 10,000 psi. Finally, the mixture was sieved through a 5 μm sieve to remove large particles, resulting in spherical silica slurry.

[0044] Example 2

[0045] (1) Raw material compounding

[0046] Set D50=0.78μm, D100=3.5μm, SSA=5.2m 2 / g of submicron spherical silica with D50 = 2.0μm, D100 = 3.5μm, and SSA = 1.8m 2 Micron-sized spherical silica particles of 1 g were mixed at a mass ratio of 1:2 to obtain particles with D50 = 1.2 μm, D100 = 3.5 μm, and SSA = 4.8 μm. 2 / g of spherical silica A;

[0047] (2) Wet modification

[0048] Spherical silica A and deionized water were mixed evenly at a mass ratio of 6:4 and then fed into a sand mill for pre-dispersion at a temperature controlled at 60℃. After uniform dispersion, a submicron slurry was obtained. Then, 0.8% of 3-glycidylpropyltrimethoxysilane KBM-403 (Shin-Etsu Chemical) was added, and the mixture was wet-milled for preliminary modification. The pre-modified slurry was then fed into a flash dryer for further drying modification at an inlet air temperature of 150℃ until the moisture content was ≤0.3%. After drying, the slurry was fed into a collector for heat preservation at 100℃ for 60 minutes to complete the secondary modification. The heat-preserved material was then depolymerized using an air jet mill at a pressure of 1.0 MPa to obtain wet-modified spherical silica B.

[0049] (3) Secondary modification

[0050] Spherical silica B was added to a high-speed mixer along with dimethyldimethoxysilane KBM-22 (Shin-Etsu Chemical). The mixture was modified at 100°C for 20 minutes to obtain secondary modified spherical silica C. The mass ratio of dimethyldimethoxysilane KBM-22 to spherical silica B was 0.3:100.

[0051] (4) Slurrying

[0052] Spherical silica C and organic solvent methyl ethyl ketone were added to a mixing tank at a mass ratio of 7:3 for initial dispersion. Then, the mixture was further dispersed using a homogenizer under a pressure of 10,000 psi. Finally, the mixture was sieved through a 10 μm sieve to remove large particles, resulting in spherical silica slurry.

[0053] Example 3

[0054] (1) Raw material compounding

[0055] Set D50=0.36μm, D100=0.87μm, SSA=11.6m 2 / g submicron spherical silica and D50 = 1.1μm, D100 = 2.0μm, SSA = 3.2m 2 Micron-sized spherical silica particles of 1 g were mixed at a mass ratio of 1:2 to obtain particles with D50 = 0.59 μm, D100 = 2.0 μm, and SSA = 6.0 μm. 2 / g of spherical silica A;

[0056] (2) Wet modification

[0057] Spherical silica A and deionized water were mixed evenly at a mass ratio of 4:6 and then fed into a sand mill for pre-dispersion at a temperature controlled at 60℃. After uniform dispersion, a submicron slurry was obtained. Then, 2.0% of 3-ureapropyltriethoxysilane KBE-585 (Shin-Etsu Chemical) was added, and the mixture was wet-milled for preliminary modification. The pre-modified slurry was then fed into a flash dryer for further drying modification at an inlet air temperature of 220℃ until the moisture content was ≤0.3%. After drying, the slurry was fed into a collector for heat preservation at 120℃ for 30 minutes to complete the secondary modification. The heat-preserved material was then depolymerized using an air jet mill at a pressure of 1.0 MPa to obtain wet-modified spherical silica B.

[0058] (3) Secondary modification

[0059] Spherical silica B was added to a high-speed mixer along with hexamethyldisilazane SZ-13 (Shin-Etsu Chemicals), and modified at 110°C for 20 min to obtain secondary modified spherical silica C. The mass ratio of hexamethyldisilazane SZ-13 to spherical silica B was 0.8:100.

[0060] (4) Slurrying

[0061] Spherical silica C and organic solvent methyl ethyl ketone were added to a mixing tank at a mass ratio of 7:3 for initial dispersion. Then, the mixture was further dispersed using a homogenizer under a pressure of 10,000 psi. Finally, the mixture was sieved through a 5 μm sieve to remove large particles, resulting in spherical silica slurry.

[0062] Example 4

[0063] (1) Raw material compounding

[0064] Set D50=0.50μm, D100=2.6μm, SSA=6.6m 2 / g of submicron spherical silica with D50 = 1.5μm, D100 = 2.2μm, and SSA = 2.6m 2 Micron-sized spherical silica particles of 1 g were mixed at a mass ratio of 1:1 to obtain particles with D50 = 0.93 μm, D100 = 2.6 μm, and SSA = 4.6 μm. 2 / g of spherical silica A;

[0065] (2) Wet modification

[0066] Spherical silica A and deionized water were mixed evenly at a mass ratio of 3:7 and then fed into a sand mill for pre-dispersion at a temperature controlled at 70℃. After uniform dispersion, a submicron slurry was obtained. Then, 1.0% of 3-isocyanate propyltriethoxysilane KBE-9007N (Shin-Etsu Chemical) was added, and the mixture was wet-milled for modification, completing the initial modification. The pre-modified slurry was then fed into a flash dryer for drying modification at an inlet air temperature of 180℃ until the moisture content was ≤0.3%. After drying, the slurry was fed into a collector for heat preservation at 100℃ for 60 minutes, completing the secondary modification. The heat-preserved material was then depolymerized using an air jet mill at a pressure of 1.0 MPa to obtain wet-modified spherical silica B.

[0067] (3) Secondary modification

[0068] Spherical silica B was added to a high-speed mixer along with methyltrimethoxysilane KBM-13 (Shin-Etsu Chemical). The mixture was modified at 100°C for 20 minutes to obtain secondary modified spherical silica C. The mass ratio of methyltrimethoxysilane KBM-13 to spherical silica B was 0.5:100.

[0069] (4) Slurrying

[0070] Spherical silica C and organic solvent MIBK were added to a mixing tank at a mass ratio of 7:3 for initial dispersion. Then, the mixture was dispersed using a homogenizer under a pressure of 10,000 psi. Finally, the mixture was sieved through a 5 μm sieve to remove large particles, resulting in spherical silica slurry.

[0071] Comparative Example 1

[0072] This comparative example is roughly the same as Example 1, except that dry modification is used in step (2). Specifically, spherical silica A is added to a high-speed mixer and stirred, while 0.6% of KBM-573 (Shin-Etsu Chemical) aniline silane coupling agent is added. The mixture is modified at 110°C for 30 minutes to obtain spherical silica B.

[0073] Comparative Example 2

[0074] This comparative example is largely the same as Example 1, except that micron-sized spherical silica was not added in step (1).

[0075] Comparative Example 3

[0076] This comparative example is largely the same as Example 1, except that the silane coupling agent in step (2) is vinyltrimethoxysilane KBM-1003.

[0077] Comparative Example 4

[0078] This comparative example is largely the same as Example 1, except that step (3) is omitted.

[0079] Comparative Example 5

[0080] This comparative example is largely the same as Example 1, except that the silane coupling agent in step (3) is decyltrimethoxysilane KBM-3103 (Shin-Etsu Chemical).

[0081] The stability of the silica slurries prepared in the examples and comparative examples was tested, and the results are shown in Table 1.

[0082] Table 1 shows the sedimentation results of the silica slurries prepared in the examples and comparative examples.

[0083]

[0084]

[0085] Table 1 shows that after one month of storage, Examples 1-4 had less stratification height and no sediment at the bottom after inversion, indicating that the slurry products of the examples all had good stability. Compared with Example 1, Comparative Example 1 used a different modification process in step (2). Example 1 used wet modification, while Comparative Example 1 used dry modification. Comparative Example 1 had a higher stratification height and sediment at the bottom, indicating that wet modification is beneficial to improving sedimentation stability. Compared with Example 1, Comparative Example 2 did not add micron-sized spherical silica to the raw materials, while Comparative Example 2 had a slightly lower stratification height and no sediment at the bottom. The stability of the slurry product was also better, indicating that although the addition of micron-sized spherical silica was not conducive to sedimentation stability, the effect was not significant. Compared with Example 1, Comparative Example 3 used a different type of modifier in step (2), while the stratification height in Comparative Example 3 was close to that of Example 1, and there was no sediment at the bottom. The stability of the slurry product was still good, indicating that the type of modifier in step (2) had no significant effect on the stability of the slurry product. Compared with Example 1, Comparative Example 4 did not include step 3, but the slurry product had a greater layer height and sediment at the bottom, indicating that step 3 can improve sedimentation stability. Compared with Example 1, Comparative Example 5 used a different modifier, the long-chain alkylsilane KBM-3103. The slurry product of Comparative Example 5 had a greater layer height and sediment at the bottom, indicating that the alkylsilane chain length in step (3) affects the stability of the product.

[0086] The advanced foreign slurry product SC2050MT*, as well as the slurry products from the examples and comparative examples, were used in the formulation of BT resin encapsulation substrates, with a filler ratio of 65%. The melt viscosity of the product and the weight loss rate of the substrate after desmearing were tested. The lower the desmear weight loss rate, the smaller the surface roughness of the substrate after desmearing, indicating better alkali resistance. The melt viscosity of the product and the desmear weight loss rate of the substrate are shown in Table 2.

[0087] Table 2. Melt viscosity and weight loss of the packaging substrates prepared in the examples and comparative examples after desmearing.

[0088]

[0089]

[0090] As can be seen from Table 2, the minimum melt viscosity of all examples is close to that of SC2050MT*, and the weight loss after desmearing is lower than that of SC2050MT*, indicating that the fluidity of the product of this invention is close to that of foreign counterparts, and its alkali resistance is better than that of foreign counterparts. Compared with Example 1, Comparative Example 1 uses a different modification process in step (2). Example 1 uses wet modification, while Comparative Example 1 uses dry modification. Comparative Example 1 has a larger weight loss and melt viscosity after desmearing, indicating that the wet modification method of this invention has good alkali resistance and low melt viscosity. Compared with Example 2, Comparative Example 1 does not contain micron-sized spherical silica, while Comparative Example 2 has a larger weight loss and melt viscosity after desmearing, indicating that the addition of micron-sized spherical silica can improve alkali resistance and melt viscosity. Compared with Example 1, Comparative Example 3 uses a different type of modifier in step (2), while Comparative Example 3 has a larger weight loss and melt viscosity after desmearing, indicating that the type of modifier in step (2) affects the alkali resistance and melt viscosity of the slurry product. Compared with Example 1, Comparative Example 4 did not include step (3). However, the product of Comparative Example 4 had a larger weight loss rate and higher melt viscosity after desmearing, indicating that step (3) can improve alkali resistance and melt viscosity. Compared with Example 1, Comparative Example 5 used a different modifier. Comparative Example 5 used a long-chain alkylsilane KBM-3103. The slurry product of Comparative Example 5 had a slightly larger weight loss rate and higher melt viscosity after desmearing, indicating that the alkylsilane chain length in step (3) affects the alkali resistance and melt viscosity of the product.

Claims

1. A method for preparing alkali-resistant spherical silica slurry for packaging substrates, characterized in that, The specific steps are as follows: (1) Raw material compounding: Set D50=0.3-0.8μm, D100≤5.0μm, SSA=4.0-12.0m 2 / g of submicron spherical silica with D50=1.0-3.0μm, D100≤5.0μm, and SSA=0.5-4.0m 2 Micron-sized spherical silica ( / g) is mixed at a mass ratio of 1:3-3:1 to obtain D50 = 0.4-2.0 μm, D100 ≤ 5.0 μm, and SSA = 1.5-9.0 μm. 2 / g of spherical silica A; (2) Wet modification: Spherical silica A and water are mixed evenly at a mass ratio of 3:7-6:

4. After pre-dispersion, a submicron slurry is obtained. Then, a modifier is added, and the mixture is subjected to wet grinding for preliminary modification. The pre-modified slurry is then dried at 120-300℃ until the moisture content is ≤0.3%. After drying, the mixture is kept at 60-120℃. Finally, the material after heat preservation is depolymerized to a particle size consistent with that of spherical silica A to obtain wet-modified spherical silica B. The modifier is selected from epoxy, aniline, isocyanate, or urea-based silane coupling agents. (3) Secondary modification: Spherical silica B is modified twice using a nonpolar short-chain silane coupling agent to obtain modified spherical silica C. The short-chain silane coupling agent is a short-chain alkyl silane coupling agent or a silazane. The short-chain alkyl silane is selected from methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, dimethyldimethoxysilane, or trimethylmethoxysilane. The silazane is hexamethyldisilazane or tetramethyldisilazane. The modification equipment is a high-speed mixer, the modification temperature is 80-150℃, and the modification time is 10-40 min. (4) Slurry preparation: Spherical silica C is pre-dispersed in an organic solvent under stirring, then dispersed in a disperser, and then graded to remove large particles to obtain spherical silica slurry. The organic solvent is acetone, butanone, methyl isobutyl ketone, or cyclohexanone.

2. The preparation method according to claim 1, characterized in that, In step (2), a sand mill is used for pre-dispersion at a temperature of 50-90℃ and a holding time of 20-60 min. An air jet mill is used for depolymerization at a pressure ≥1.0 MPa.

3. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the modifier to spherical silica A is 0.1-2.0:

100.

4. The preparation method according to claim 1, characterized in that, In step (2), the epoxy silane coupling agent is 3-glycidylpropyltrimethoxysilane, the aniline silane coupling agent is N-phenyl-3-aminopropyltrimethoxysilane, the isocyanate silane coupling agent is 3-isocyanate propyltriethoxysilane, and the ureosilane coupling agent is 3-ureapropyltriethoxysilane.

5. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of the nonpolar short-chain silane coupling agent to the spherical silica B is 0.1-1.0:

100.

6. The preparation method according to claim 1, characterized in that, In step (4), the mass ratio of spherical silica C to organic solvent is 25:75-50:

50.

7. The preparation method according to claim 1, characterized in that, In step (4), the disperser is a high-pressure homogenizer with a dispersion pressure of 10,000 psi-20,000 psi; the equipment used for grading is a wet vibrating screen with a screen aperture of ≤10 μm.

8. The spherical silica slurry prepared by any one of claims 1 to 7.

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