PREPARATION METHOD FOR POLYSILOXANE POWDER FILLER, POLYSILOXANE POWDER FILLER OBTAINED THEREBY AND APPLICATION THEREOF

Abstract

Disclosed is a preparation method for a polysiloxane powder filler. The method comprises: providing polysiloxane which contains at least 60 wt % of T unit, wherein T unit is equal to R.sub.1SiO.sub.3-, R.sub.1 is a hydrogen atom or an independently selected organic group comprising 1-18 carbon atoms; and performing heat treatment on the polysiloxane under inert gas atmosphere or vacuum conditions, wherein the heat treatment temperature is 250 to 750 degrees, such that silicon hydroxyl groups in the polysiloxane are condensed to obtain a polysiloxane powder filler having a true density greater than or equal to 1.33 g/cm.sup.3 and more preferably greater than or equal to 1.34 g/cm.sup.3. The polysiloxane powder filler obtained by the described preparation method has low inductivity, low inductivity loss and low radioactivity; and can be used for semiconductor packaging materials, circuit boards and intermediate semi-finished products thereof, and semi-cured sheets or copper clad laminates of high-frequency high-speed circuit boards.

Claims

1. A preparation method for a polysiloxane powder filler, comprising the steps of: S1, providing polysiloxane which contains at least 60 wt % of T unit, wherein T unit=R.sub.1SiO.sub.3-, R.sub.1 is a hydrogen atom or an independently selected organic group comprising 1-18 carbon atoms; and S2, performing heat treatment on the polysiloxane under inert gas atmosphere or vacuum conditions, wherein the heat treatment temperature is 300 to 700 degrees, such that silicon hydroxyl groups in the polysiloxane are condensed to obtain a polysiloxane powder filler having a true density greater than or equal to 1.33 g/cm.sup.3.

2. The preparation method according to claim 1, wherein in the step S2, the heat treatment on the polysiloxane is performed under inert gas atmosphere or vacuum conditions, wherein the heat treatment temperature is 300 to 700 degrees, such that silicon hydroxyl groups in the polysiloxane are condensed to obtain the polysiloxane powder filler having a true density greater than or equal to 1.34 g/cm.sup.3.

3. The preparation method according to claim 1, wherein in the step S1, the polysiloxane is prepared by a reaction of methyltrichlorosilane and water.

4. The preparation method according to claim 1, wherein the polysiloxane contains 90%-100% of T unit.

5. The preparation method according to claim 1, wherein R.sub.1 in the T unit is methyl.

6. The preparation method according to claim 1, wherein the preparation method further comprises treating the polysiloxane powder filler on surface by a treatment agent, wherein the treatment agent includes a silane coupling agent, which is (R.sub.7).sub.a(R.sub.8).sub.bSi(M).sub.4-a-b, wherein each of R.sub.7, R.sub.8 is a hydrogen atom, an independently selected hydrocarbyl comprising 1-18 carbon atoms, or an independently selected hydrocarbyl comprising 1-18 carbon atoms replaced by functional groups, wherein the functional group is at least one group selected from following organic functional groups: vinyl, allyl, styryl, epoxy group, aliphatic amino, aromatic amino, methacryloxypropyl, acryloxypropyl, ureidopropyl, chloropropyl, mercaptopropyl, polysulfide group, isocyanate propyl, M is an alkoxy group comprising 1-18 carbon atoms or a halogen atom, a=0, 1, 2 or 3, b=0, 1, 2 or 3, and a+b=1, 2 or 3; and/or the treatment agent includes disilazane, which is (R.sub.9R.sub.10R.sub.11)SiNHSi(R.sub.12R.sub.13R.sub.14), wherein each of R.sub.9, R.sub.10, R.sub.11, R.sub.12, R.sub.13, R.sub.14 is a hydrogen atom or an independently selected hydrocarbyl comprising 1-18 carbon atoms.

7. The preparation method according to claim 1, wherein the preparation method comprises removing coarse oversize particles above 1, 3, 5, 10, 20, 45, 55 or 75 microns in the polysiloxane powder filler by dry or wet sieving or inertial classification.

8. The preparation method according to claim 1, wherein the polysiloxane powder filler has a particle size of 0.1-50 microns.

9. The preparation method according to claim 8, wherein the polysiloxane powder filler of different particle sizes is tightly packed and graded in resin to form a composite material.

10. The preparation method according to claim 9, wherein the composite material is suitable for semiconductor packaging materials, circuit boards and intermediate semi-finished products thereof, and semi-cured sheets or copper clad laminates of high-frequency high-speed circuit boards.

Description

DESCRIPTION OF THE ENABLING EMBODIMENT

[0034] The preferred embodiments of the present invention are given below and described in detail.

[0035] The detection methods involved in the following embodiments include:

[0036] The average particle size was measured by a laser particle size distribution instrument HORIBA LA-700, and the solvent was isopropanol.

[0037] The specific surface area was measured by SHIMADZU FlowSorbIII2305.

[0038] The true density was measured by MicrotracBEL BELPycno, and the gas used for measurement was helium.

[0039] The weight loss after heating at 200 degrees for 2 hours was weighed by an analytical balance, and the heated sample was cooled in a dry air container and then weighed. The heated sample absorbed water to gain weight when placed in the atmosphere, indicating that the weight loss after heating was the water absorbed by the polysiloxane. The sample before the test was placed in the atmosphere for more than 1 hour to allow the sample to absorb water in the atmosphere to reach a saturated state. The atmosphere mentioned here refers to the natural atmosphere in the subtropical area.

[0040] The content of uranium and thorium was measured by Agilent 7700X ICP-MS. The sample was prepared by total dissolution in hydrofluoric acid after burning at 800 degrees.

[0041] The content of Q, T, D, or M unit was measured by solid .sup.28Si-NMR nuclear magnetic resonance spectrum of JEOL ECS-400 Nuclear magnetic resonance instrument, wherein the Q unit content was calculated from the peak integrated area between −80 ppm and −120 ppm, the T unit content was calculated from the peak integrated area between −30 ppm and −80 ppm, the D unit content was calculated from the peak integrated area between −10 ppm and −30 ppm; and the M unit content was calculated from the peak integrated area between +20 ppm and −10 ppm; referring to Separation and Purification Technology Volume 25, Issues 1-3, 1 Oct. 2001, Pages 391-397, 29Si NMR and Si2p XPS correlation in polysiloxane membranes prepared by plasma enhanced chemical vapor deposition.

[0042] The inductivity or inductivity loss was measured by KEYCOM inductivity or inductivity loss measuring device Model No. DPS18 in perturbation method and sample hole block-shaped cavity resonance method.

[0043] In this text, temperature degree refers to “degrees Celsius”, that is, ° C.

[0044] Referring to method of “Spherical Silicone Resin Micropowder”, Huang Wenrun, Organic Silicone Materials, 2007, 21(5) 294-299, wherein the raw material was Methyltrimethoxysilane, and method of PCT/CN2018/124685, wherein the raw material was Methyltrichlorosilane, the spherical siloxane of different compositions in Examples and Comparative Examples was prepared for subsequent heat treatment.

[0045] Methyltrichlorosilane was added into water to provide a white precipitate. After being washed with deionized water, the precipitate was ground by a sand mill to a fine powder of 2 microns in Examples and Comparative Examples for subsequent heat treatment. Observed by an electron microscope, the prepared powder contains spherical polysiloxane.

Embodiment 1

[0046] The polysiloxane of 100% T unit (R is methyl) with an average particle size of 2 microns was heat-treated at different temperatures in air or nitrogen atmosphere. The powder was separated by cyclone to remove coarse oversize particles above 10 microns to obtain samples of Examples and Comparative Examples. The analysis results of the samples were listed in Table 1.

TABLE-US-00001 TABLE 1 Average Heat Weight Loss Particle Heat Treatment Treatment True after heating Inductivity Size Temperature Time density at 200° C. for 2 Inductivity Loss μm ° C. h Atmosphere g/cm.sup.3 hours % 500 MHz 500 MHz Example 1 2.0 350 20 nitrogen 1.33 0.09 2.9 0.003 Example 2 2.0 450 2 nitrogen 1.36 0.04 2.6 <0.001 Example 3 2.0 650 1 nitrogen 1.38 0.05 2.6 <0.001 Comparative 2.0 350 20 air 1.37 0.9 3.1 0.01 Example 1 Comparative 2.0 450 2 air 1.85 2.9 4.9 0.02 Example 2 Comparative 2.0 650 1 air 2.1 3.5 5.1 0.03 Example 3 Comparative 2.0 commercial Tospearl120 1.32 1.2 2.9 0.009 Example 4

[0047] Obviously, for each of the samples obtained according to Examples 1-3, the inductivity was less than 3 and the inductivity loss was less than 0.005, meeting the requirement of low inductivity (less signal delay) and low inductivity loss (less signal loss) of the filler in the 5G era. For each of the samples obtained by heat-treating in air atmosphere according to Comparative Examples 1-3, the inductivity was greater than 3 and the inductivity loss was greater than 0.005, and for the sample of Comparative Example 4, the inductivity loss was greater than 0.005, failing to meet the requirement of low inductivity (less signal delay) and low inductivity loss (less signal loss) of the filler in the 5G era.

Embodiment 2

[0048] The polysiloxane of 100% T unit (R.sub.1 is methyl) with an average particle size of 2 microns was heat-treated in nitrogen atmosphere. The treated powder was treated with 0.5% vinyltrimethoxysilane, and then heated at 130° C. for 6 hours. The powder was separated by cyclone to remove coarse oversize particles above 10 microns to obtain the sample of Example 4. The analysis results of the sample were listed in Table 2.

The polysiloxane of 100% T unit (R.sub.1 is vinyl) with an average particle size of 2 microns was heat-treated in nitrogen atmosphere. The treated powder was treated with a mixture of 1% phenyltrimethoxysilane and 1% hexamethyldisilazane (the weight of the treatment agent is equal to 2%), and then heated at 130° C. for 6 hours. The powder was separated by cyclone to remove coarse oversize particles above 10 microns to obtain the sample of Example 5. The analysis results of the sample were listed in Table 2.

TABLE-US-00002 TABLE 2 Average Heat Weight Loss Particle Heat Treatment Treatment after heating at True Inductivity Size Temperature Time 200° C. for 2 density Inductivity Loss μm ° C. h Atmosphere hours % g/cm.sup.3 500 MHz 500 MHz Example 2.0 430 2 nitrogen 0.05 1.35 2.6 <0.001 4 Example 2.0 430 2 nitrogen 0.06 1.34 2.7 <0.001 5

[0049] Obviously, for each of the samples obtained according to Examples 4-5, the inductivity was less than 3 and the inductivity loss was less than 0.005, meeting the requirement of low inductivity (less signal delay) and low inductivity loss (less signal loss) of the filler in the 5G era.

Embodiment 3

[0050] Methyltrichlorosilane was added into water to provide a white precipitate. After being washed with deionized water, the precipitate was ground by a sand mill to a fine powder of 2 microns. Observed by an electron microscope, the prepared powder contains spherical polysiloxane. After filtration and drying, the heat treatment was performed in nitrogen atmosphere. The treated powder was mixed and treated with 5% vinyl silane coupling agent, and then heated at 130° C. for 6 hours. The powder was separated by cyclone to remove coarse oversize particles above 10 microns to obtain the sample of Example 6. The analysis results of the sample were listed in Table 3.

TABLE-US-00003 TABLE 3 Average Heat Weight Loss Particle Heat Treatment Treatment True after heating at Inductivity Size Temperature Time density 200° C. for 2 Inductivity Loss μm ° C. h Atmosphere g/cm.sup.3 hours % 500 MHz 500 MHz Example 2.0 450 3 nitrogen 1.37 0.05 2.6 <0.001 6

[0051] Obviously, for the sample obtained according to Example 6, the inductivity was less than 3 than 3 and the inductivity loss was less than 0.005, meeting the requirement of low inductivity (less signal delay) and low inductivity loss (less signal loss) of the filler in the 5G era.

Embodiment 4

[0052] The polysiloxane of 100% T unit (R.sub.1 is methyl) with different average particle sizes was heat-treated at different temperatures in vacuum or nitrogen atmosphere. The powder was separated by a vibrating screen to remove coarse oversize particles above 45 microns to obtain samples of Examples 7-10. The analysis results of the samples were listed in Table 4.

TABLE-US-00004 TABLE 4 Average Heat Weight Loss Particle Heat Treatment Treatment True after heating at Inductivity Size Temperature Time density 200° C. for 2 Inductivity Loss μm ° C. h Atmosphere g/cm.sup.3 hours % 500 MHz 500 MHz Example 0.5 430 2 nitrogen 1.35 0.07 2.8 0.002 7 Example 5.0 430 2 nitrogen 1.35 0.05 2.7 <0.001 8 Example 10 430 2 nitrogen 1.35 0.05 2.7 <0.001 9 Example 30 430 2 vacuum 1.34 0.04 2.6 <0.001 10

[0053] Obviously, for each of the samples obtained according to Examples 7-10, the inductivity was less than 3 and the inductivity loss was less than 0.005, meeting the requirement of low inductivity (less signal delay) and low inductivity loss (less signal loss) of the filler in the 5G era. For each of the samples obtained by heat-treating in an air atmosphere according to Comparative Examples 1-4, the inductivity was greater than 3 and the inductivity loss was greater than 0.005, failing to meet the requirement of low inductivity (less signal delay) and low inductivity loss (less signal loss) of the filler in the 5G era.

[0054] It should be understood that samples of above Examples 1-10 can be vertex cut to remove coarse oversize particles. Specifically, coarse oversize particles above 1, 3, 5, 10, 20, 45, 55, or 75 μm in the polysiloxane powder filler can be removed by dry or wet sieving or inertial classification according to the size of the semiconductor chip. Further, Uranium or thorium content of samples of above Examples 1-10 was less than 0.5 ppb, wherein the samples were dissolved in hydrofluoric acid and measured by ICP-MS.

[0055] The foregoing description refers to preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Various changes can be made to the foregoing embodiments of the present invention. That is to say, all simple and equivalent changes and modifications made in accordance with the claims of the present invention and the content of the description fall into the protection scope of the patent of the present invention. What is not described in detail in the present invention is conventional technical content.