A polyurethane composite polishing pad and its preparation method

Abstract

This invention discloses a polyurethane composite polishing pad and its preparation method, belonging to the field of polishing pad preparation technology. First, 10-20 parts by weight of polyurethane resin, 70-95 parts by weight of solvent, 3-5 parts by weight of abrasive, and 5-10 parts by weight of reinforcing components are added to a mixer and stirred for 0.5-1 hours to obtain an impregnation solution. At room temperature, the substrate is impregnated in the impregnation solution, and then placed in water for pre-coagulation for 10-30 minutes. After pre-coagulation, it is dried. Addressing the problems of poor thermal conductivity and wear resistance in existing composite polishing pads, this invention provides a polyurethane composite polishing pad using non-woven or woven fabric as the substrate. By introducing reinforcing components into the polyurethane impregnation solution, the thermal conductivity and wear resistance of the polishing pad are improved without reducing its water permeability, thereby increasing the service life of the polishing pad.

Description

Technical Field

[0001] This invention belongs to the field of polishing pad preparation technology, specifically relating to a polyurethane composite polishing pad and its preparation method. Background Technology

[0002] Polishing pads are an important component of consumable materials in chemical mechanical polishing (CMP) systems, serving to store polishing fluid and evenly distribute it throughout the workpiece's processing area. Polyurethane / non-woven composite polishing pads are composite materials developed based on polyurethane polishing pads. They have a relatively rough surface, offering good polishing precision and excellent polishing fluid retention capacity. They are widely used for polishing semiconductor materials such as silicon wafers, optical glass, and magnetic optical discs, and have attracted considerable attention.

[0003] The polyurethane microporous membrane in polyurethane / nonwoven composite polishing pads, due to prolonged close contact with the polished object and repeated friction, generates heat that is difficult to dissipate in time and results in mass loss, often leading to aging and wear of the polyurethane microporous membrane. To address the poor wear resistance and thermal conductivity of the polyurethane microporous membrane in existing composite polishing pads, nano-carbon black has been introduced into the polyurethane microporous membrane to improve this phenomenon. However, nano-carbon black is prone to agglomeration and is difficult to disperse evenly in the polyurethane microporous membrane, resulting in generally poor thermal conductivity and wear resistance. Consequently, this technique cannot achieve the desired technical effect. Therefore, it is necessary to provide a polyurethane composite polishing pad with better performance. Summary of the Invention

[0004] The purpose of this invention is to provide a polyurethane composite polishing pad and its preparation method to solve the problems in the background art.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a polyurethane composite polishing pad includes the following steps:

[0007] At room temperature, the substrate is immersed in the impregnation solution, and then placed in water for pre-coagulation for 10-30 minutes. After pre-coagulation, it is dried to obtain the polyurethane composite polishing pad.

[0008] As a further aspect of the present invention, the impregnation solution is prepared by the following steps:

[0009] Add 10-20 parts by weight of polyurethane resin, 70-95 parts by weight of solvent, 3-5 parts by weight of polishing agent and 5-10 parts by weight of reinforcing component to a mixer and stir for 0.5-1 hour.

[0010] As a further aspect of the present invention, the impregnation adopts an alternating impregnation-rolling process, and the rolling is carried out by a rubber roller device with a rotation speed of 1-5 r / min and a rolling pressure of 9-11 MPa.

[0011] As a further aspect of the present invention, the mass percentage of organic solvent in the water during the pre-coagulation process is ≤2%, the drying temperature is 120-160℃, and the drying time is 1-2h.

[0012] As a further aspect of the present invention, the reinforcing component is prepared by the following steps:

[0013] Step S1: Add hBN-COOH, thionyl chloride and DMF to the reaction vessel, heat to 70℃ and stir for 24 h, then remove the solvent under reduced pressure to obtain boron nitride acyl chloride.

[0014] In the above reaction, the carboxyl group of hBN-COOH was chlorinated using a thionyl chloride and DMF system. The ratio of hBN-COOH, thionyl chloride and DMF was 0.4-0.5g:20-40mL:2mL. hBN-COOH (carboxyl-modified boron nitride nanosheets) was purchased from Xi'an Ruixi Biotechnology Co., Ltd.

[0015] Step S2: Add boron nitride chloride and DMF to the reactor, stir for 15 min, then add hyperbranched polyester and pyridine, heat to 110℃ and stir for 48 h. After the reaction is completed, cool to room temperature, filter, wash the filter cake with deionized water 3-5 times, and dry to obtain the reinforcing component.

[0016] In the above reaction, under the action of pyridine, the acyl chloride group of boron nitride chloride reacts with the terminal hydroxyl group of hyperbranched polyester, and the hyperbranched polyester is chemically bonded to the surface of boron nitride to obtain the reinforcing component. The ratio of boron nitride chloride, DMF, hyperbranched polyester and pyridine is 0.4-0.6g: 20-30mL: 2.5-3.5g: 0.5mL.

[0017] As a further aspect of the present invention, the hyperbranched polyester is prepared by the following steps:

[0018] Trimethylolpropane, sodium isophthalic acid-5-sulfonate, DMF, and p-toluenesulfonic acid were added to a reactor. Under nitrogen protection, the reaction temperature was controlled at 130°C and maintained for 2 hours. The temperature was then increased to 150°C, and the reaction was carried out under vacuum for another 2 hours. After the reaction was completed, DMF was removed by vacuum distillation to obtain a hyperbranched polyester. The molar ratio of trimethylolpropane, sodium isophthalic acid-5-sulfonate, and p-toluenesulfonic acid was 1:1:0.01. Using trimethylolpropane and sodium isophthalic acid-5-sulfonate as monomers and p-toluenesulfonic acid as a catalyst, a esterification reaction was carried out to obtain a hyperbranched polyester with terminal hydroxyl groups containing sulfonic acid structures.

[0019] As a further aspect of the present invention, the solvent is one or more of DMF, acetone, methyl ethyl ketone, cyclohexanone, and butanone.

[0020] As a further aspect of the present invention, the polishing agent is one or more of the following: silicon dioxide powder, titanium dioxide powder, silicon carbide powder, zirconium oxide powder, cerium oxide powder, aluminum oxide powder, and diamond powder.

[0021] As a further embodiment of the present invention, the substrate is a nonwoven or woven fabric of polyester, polyamide, polyolefin, or polyphenylene sulfide, preferably a nonwoven fabric of polyester or polyamide, with a substrate thickness of 2-3 mm and a density of 300-700 g / m³.

[0022] As a further aspect of the present invention, a polyurethane composite polishing pad is prepared by the above-described preparation method.

[0023] The beneficial effects of this invention are:

[0024] 1. In view of the problems of poor thermal conductivity and wear resistance of existing composite polishing pads, the present invention provides a polyurethane composite polishing pad, which uses non-woven fabric or woven fabric as the base material. By introducing reinforcing components into the polyurethane impregnation liquid, the thermal conductivity and wear resistance of the polishing pad are improved without reducing the water permeability of the polishing pad, thereby improving the service life of the polishing pad.

[0025] 2. Based on the high thermal conductivity and high wear resistance of boron nitride, this invention introduces it as a reinforcing component into the microporous polyurethane layer through modification treatment to improve the thermal conductivity and wear resistance of the microporous polyurethane layer. Compared with directly adding boron nitride nanosheets, this invention first selects boron nitride nanosheets with active carboxyl groups on the surface as the substrate, and then grafts terminal hydroxyl hyperbranched polyester with sulfonic acid structure onto its surface. Based on the characteristics of hyperbranched polymer such as high branching degree and low viscosity, the boron nitride nanosheets are improved in the base material and play a role in toughening the polyurethane. In addition, the hyperbranched polyester contains a large number of active hydroxyl groups, which can participate in the curing reaction of polyurethane and "anchor" the boron nitride nanosheets in the microporous membrane, thereby stably exerting the thermal conductivity and wear resistance. More importantly, the sulfonic acid structure of the hyperbranched polyester can improve the hydrophilicity of the microporous membrane, thereby improving its water permeability and better storing and transporting polishing fluid.

[0026] 3. The impregnation liquid in this invention also contains a wear-resistant agent. During the thermosetting process, the wear-resistant agent is evenly distributed between the lamellar structures of the reinforcing components to form a complete three-dimensional filling layer, forming a more effective wear-resistant layer and giving the polishing pad excellent wear resistance. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] An enhancing component is prepared by the following steps:

[0030] Step S1: Add 0.4g hBN-COOH, 20mL thionyl chloride and 2mL DMF to the reaction vessel, heat to 70℃ and stir for 24h. Remove the solvent under reduced pressure to obtain boron nitride acyl chloride. hBN-COOH (carboxyl-modified boron nitride nanosheets) was purchased from Xi'an Ruixi Biotechnology Co., Ltd.

[0031] Step S2: Add 0.4g boron nitride acyl chloride and 20mL DMF to the reaction vessel, stir for 15min, then add 2.5g hyperbranched polyester and 0.5mL pyridine, heat to 110℃ and stir for 48h. After the reaction is completed, cool to room temperature, filter, wash the filter cake three times with deionized water, and dry to obtain the reinforcing component.

[0032] The hyperbranched polyester is prepared by the following steps:

[0033] 0.1 mol of trimethylolpropane, 0.1 mol of sodium isophthalic acid-5-sulfonate, 500 mL of DMF and 0.001 mol of p-toluenesulfonic acid were added to a reaction vessel. Under nitrogen protection, the reaction temperature was controlled at 130 °C and maintained for 2 h. The temperature was then increased to 150 °C, and a vacuum was applied for another 2 h. After the reaction was completed, DMF was removed by vacuum distillation to obtain hyperbranched polyester.

[0034] Example 2

[0035] An enhancing component is prepared by the following steps:

[0036] Step S1: Add 0.5g hBN-COOH, 40mL thionyl chloride and 2mL DMF to the reaction vessel, heat to 70℃ and stir for 24h. Remove the solvent under reduced pressure to obtain boron nitride acyl chloride. hBN-COOH (carboxyl-modified boron nitride nanosheets) was purchased from Xi'an Ruixi Biotechnology Co., Ltd.

[0037] Step S2: Add 0.6g of boron nitride acyl chloride and 30mL of DMF to the reaction vessel, stir for 15min, then add 3.5g of hyperbranched polyester and 0.5mL of pyridine, heat to 110℃ and stir for 48h. After the reaction is completed, cool to room temperature, filter, wash the filter cake 5 times with deionized water, and dry to obtain the reinforcing component.

[0038] The hyperbranched polyester is prepared by the following steps:

[0039] 0.1 mol of trimethylolpropane, 0.1 mol of sodium isophthalic acid-5-sulfonate, 500 mL of DMF and 0.001 mol of p-toluenesulfonic acid were added to a reaction vessel. Under nitrogen protection, the reaction temperature was controlled at 130 °C and maintained for 2 h. The temperature was then increased to 150 °C, and a vacuum was applied for another 2 h. After the reaction was completed, DMF was removed by vacuum distillation to obtain hyperbranched polyester.

[0040] Comparative Example 1

[0041] This comparative example provides an enhancing component. Compared with Example 1, the sodium isophthalic acid-5-sulfonate of Example 1 is replaced with the same molar amount of isophthalic acid, while the other raw materials and preparation process are the same as in Example 1.

[0042] Comparative Example 2

[0043] This comparative example provides an enhancing component, specifically hBN-COOH (carboxyl-modified boron nitride nanosheets), purchased from Xi'an Ruixi Biotechnology Co., Ltd.

[0044] Example 3

[0045] A method for preparing a polyurethane composite polishing pad includes the following steps:

[0046] Ten parts by weight of polyurethane resin, 70 parts by weight of solvent, 3 parts by weight of polishing agent, and 5 parts by weight of the reinforcing component of Example 1 were added to a mixer and stirred for 0.5 h to obtain an impregnation solution. At room temperature, the substrate was impregnated in the impregnation solution using an alternating impregnation-rolling process. Rolling was performed using a rubber roller device with a rotation speed of 1 r / min and a rolling pressure of 9 MPa. Afterward, the substrate was placed in water for pre-coagulation for 10 min. During the pre-coagulation process, the mass percentage of organic solvent in the water was 2%. The substrate was then treated at 120°C for 2 h to obtain a polyurethane composite polishing pad.

[0047] The solvent is DMF, the abrasive is composed of silica powder and titanium dioxide powder in a mass ratio of 1:1, and the substrate is polyester nonwoven fabric with a thickness of 2 mm and a density of 300 g / m³.

[0048] Example 4

[0049] A method for preparing a polyurethane composite polishing pad includes the following steps:

[0050] 15 parts by weight of polyurethane resin, 85 parts by weight of solvent, 4 parts by weight of polishing agent and 6 parts by weight of the reinforcing component of Example 2 were added to a mixer and stirred for 0.8 hours to obtain an impregnation solution. At room temperature, the substrate was impregnated in the impregnation solution by an alternating impregnation-rolling process. The rolling was performed using a rubber roller device with a rotation speed of 3 r / min and a rolling pressure of 10 MPa. After that, it was placed in water for pre-coagulation for 20 minutes. During the pre-coagulation process, the mass percentage of organic solvent in the water was 1%. Then, it was treated at a temperature of 150°C for 1.5 hours to obtain a polyurethane composite polishing pad.

[0051] The solvent is acetone, and the polishing agent is composed of silica powder, titanium dioxide powder and cerium oxide powder in a mass ratio of 1:1:1. The substrate is polyamide nonwoven fabric with a thickness of 3 mm and a density of 500 g / m³.

[0052] Example 5

[0053] A method for preparing a polyurethane composite polishing pad includes the following steps:

[0054] 20 parts by weight of polyurethane resin, 95 parts by weight of solvent, 5 parts by weight of polishing agent and 10 parts by weight of the reinforcing component of Example 2 were added to a mixer and stirred for 1 hour to obtain an impregnation solution. At room temperature, the substrate was impregnated in the impregnation solution using an alternating impregnation-rolling process. Rolling was performed using a rubber roller device with a rotation speed of 5 r / min and a rolling pressure of 11 MPa. After that, the substrate was placed in water for pre-coagulation for 30 minutes. During the pre-coagulation process, the mass percentage of organic solvent in the water was 0.5%. After that, the substrate was treated at a temperature of 160°C for 2 hours to obtain a polyurethane composite polishing pad.

[0055] The solvent is one or more of DMF, acetone, methyl ethyl ketone, cyclohexanone and butanone, and the polishing agent is one or more of silica powder, titanium dioxide powder, silicon carbide powder, zirconium oxide powder, cerium oxide powder, aluminum oxide powder and diamond powder.

[0056] The substrate is a nonwoven or woven fabric of polyester, polyamide, polyolefin, or polyphenylene sulfide, preferably a nonwoven fabric of polyester or polyamide, with a thickness of 2-3 mm and a density of 300-700 g / m³.

[0057] Comparative Example 3

[0058] This comparative example provides a method for preparing a polyurethane composite polishing pad. Compared with Example 3, the reinforcing component in Example 3 is replaced with the same mass of the substance in Comparative Example 1, while the remaining raw materials and preparation process are the same as in Example 3.

[0059] Comparative Example 4

[0060] This comparative example provides a method for preparing a polyurethane composite polishing pad. Compared with Example 3, the reinforcing component in Example 3 is replaced with the same mass of the substance in Comparative Example 2, while the remaining raw materials and preparation process are the same as in Example 3.

[0061] Performance tests were conducted on Examples 3-5 and Comparative Examples 3-4. The test items are as follows:

[0062] Hardness test: Performed in accordance with the standard GB / T 2411-2008 Plastics and hard rubber, determination of indentation hardness (Shore hardness) using a hardness tester;

[0063] Thermal conductivity: The thermal conductivity was measured using a thermal conductivity meter, and the average value was taken after three measurements.

[0064] Abrasion resistance test: The specific method is to attach 100-grit sandpaper to the upper plate of the polishing machine, rotate at 80 r / min, and rotate the lower plate of the polishing pad at 40 r / min, polish for 5 minutes, and record the mass loss before and after. The polishing machine is from Shenyang Kejing Automation Equipment Co., Ltd., model UNIPOL-1200S.

[0065] Water permeability: Refer to the water permeability test standard for artificial leather, GB / T4689.22—1996, calculate the time it takes for 50 mL of deionized water to flow over the sample surface, and use the formula 1800000 / (100t1-50t0) to calculate the water permeability of the sample, where t1 is the time it takes for 50 mL of water to pass through the sample, and t0 is the time it takes for 50 mL of water to flow down without a sample.

[0066] Number of surface scratches: In accordance with standard GB / T 6624-2009 "Visual Inspection Method for Surface Quality of Silicon Polished Wafers";

[0067] The results are shown in Table 1:

[0068] Table 1

[0069]

[0070] As can be seen from Table 1, compared with Comparative Examples 3 and 4, the polyurethane composite polishing pads prepared in Examples 3-5 have the characteristics of fast heat dissipation, wear resistance and high water permeability, and have a longer service life while reducing the generation of polishing scratches.

[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of making a polyurethane composite polishing pad, characterized by, The method comprises the following steps: 10-20 parts by weight of polyurethane resin, 70-95 parts by weight of solvent, 3-5 parts by weight of polishing agent and 5-10 parts by weight of reinforcing component are added into a mixing machine, and stirring and mixing are carried out for 0.5-1 h to obtain an impregnating solution; the substrate is impregnated in the impregnating solution at room temperature, and then is placed in water to carry out pre-coagulation for 10-30 min, and drying is carried out after pre-coagulation, so that the polyurethane composite polishing pad is obtained; The reinforcing component is prepared by the following steps: In step S1, hBN-COOH, thionyl chloride and DMF are added into a reaction kettle, and stirring reaction is carried out at 70℃ for 24 h; then, the solvent is removed under reduced pressure to obtain acyl chloride boron nitride; In step S2, acyl chloride boron nitride and DMF are added into a reaction kettle, and stirring is carried out for 15 min; then, hyperbranched polyester and pyridine are added, and stirring reaction is carried out at 110℃ for 48 h; after the reaction is completed, cooling is carried out to room temperature, and the filter cake is washed with deionized water for 3-5 times and dried to obtain the reinforcing component. The hyperbranched polyester is prepared by the following steps: In the reaction kettle, trimethylolpropane, sodium 5-sulfoisophthalate, DMF and p-toluenesulfonic acid are added, and under the protection of nitrogen, reaction is carried out at 130℃ for 2 h; then, the temperature is increased to 150℃, and vacuum reaction is carried out for 2 h; after the reaction is completed, DMF is removed by distillation under reduced pressure to obtain the hyperbranched polyester.

2. The method for preparing a polyurethane composite polishing pad according to claim 1, characterized in that, The amount ratio of hBN-COOH, thionyl chloride and DMF is 0.4-0.5 g: 20-40 mL: 2 mL.

3. The method for preparing a polyurethane composite polishing pad according to claim 1, characterized in that, The amount ratio of acyl chloride boron nitride, DMF, hyperbranched polyester and pyridine is 0.4-0.6 g: 20-30 mL: 2.5-3.5 g: 0.5 mL.

4. The method for preparing a polyurethane composite polishing pad according to claim 1, characterized in that, The molar ratio of trimethylolpropane, sodium 5-sulfoisophthalate and p-toluenesulfonic acid is 1:1:0.

01.

5. The method for preparing a polyurethane composite polishing pad according to claim 1, characterized in that, The impregnation is carried out by the way of impregnation-roller pressing alternation, and the roller pressing is carried out by using a rubber roller device; the rotating speed of the rubber roller is 1-5 r / min, and the roller pressing pressure is 9-11 MPa.

6. The method for preparing a polyurethane composite polishing pad according to claim 1, characterized in that, In the pre-coagulation process, the mass percentage content of organic solvent in water is ≤2%, and the drying temperature is 120-160℃, and the drying time is 1-2 h.

7. A polyurethane composite polishing pad characterized by, The polyurethane composite polishing pad is prepared by the preparation method of any one of claims 1-6.

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