A waxless pad for IC integrated circuit and a manufacturing process thereof
By introducing modified polyurethane particles and thermally conductive fillers into the wax-free pad, the problem of poor heat transfer in the center of the silicon wafer was solved, achieving efficient heat dissipation and flatness of the IC integrated circuit silicon wafer, and improving the polishing quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI HECHEN NEW MATERIAL CO LTD
- Filing Date
- 2023-04-24
- Publication Date
- 2026-06-05
AI Technical Summary
During CMP polishing, heat cannot be transferred quickly from the center of the silicon wafer, resulting in low hardness at the center of the adsorption pad, which affects the polishing quality.
The pad is made of a support layer and an adsorption layer. The support layer is composed of modified polyurethane particles and fiberglass cloth, and the adsorption layer is formed by curing polyurethane prepolymer. Thermally conductive fillers such as carbon nanotubes and nano-aluminum nitride powder are mixed into the modified polyurethane particles to improve heat dissipation performance.
It improves the heat dissipation and mechanical properties of wax-free pads, ensures the flatness of IC integrated circuit silicon wafers after polishing, and avoids quality defects.
Smart Images
Figure BDA0004196744100000101 
Figure BDA0004196744100000111
Abstract
Description
Technical Field
[0001] This invention belongs to the field of wax-free pad technology, specifically relating to a wax-free pad for IC integrated circuits and its preparation process. Background Technology
[0002] Integrated circuits (ICs) are miniature electronic devices that integrate transistors, diodes, resistors, capacitors, inductors, and interconnections required for a circuit. These components are fabricated on one or more small semiconductor wafers or dielectric substrates and then packaged in a housing to form a miniature structure with the desired circuit function. In modern large-scale integrated circuit manufacturing, multilayer metal cross-linking is commonly used to form metal-wound circuits. However, multilayer metal cross-linking technology also has drawbacks. One is that the layer-by-layer stacking effect leads to a loss of chip flatness, resulting in an uneven, undulating surface. Near areas with high convexity, these conductive or insulating films are susceptible to heat, current, or mechanical stress, causing pattern discontinuities. These discontinuities can cause certain functional failures of the component, thus requiring CMP polishing.
[0003] CMP polishing can be divided into chemical and physical processes. The chemical process refers to the chemical reaction between the chemical components in the polishing slurry and the silicon wafer surface material, converting insoluble substances into soluble substances or softening high-hardness substances to generate substances that are easier to remove. The physical process refers to the mechanical physical friction between the abrasive grains in the polishing slurry and the silicon wafer surface material, removing these chemically reacted substances from the silicon wafer surface, which are then dissolved and carried away by the flowing liquid.
[0004] Wax-free pads enable wax-free polishing of silicon wafers, offering advantages such as time-saving, labor-saving, and low cost. They are ideal for processing and polishing sapphire wafers, LCD substrates, wax-free silicon lenses, glass panels, optical crystal wafers, and laser crystal wafers. They effectively prevent wafer insertion and peeling, helping to extend the lifespan of the polishing pad while avoiding fragmentation, chipping, and scratches, thus improving the wafer polishing pass rate and efficiency.
[0005] For use in polishing silicon wafers
[0006] Patent CN112873074B discloses a method for producing a wax-free polishing pad. It uses epoxy resin and polyurethane prepolymer to react and produce a composite resin, which is then used as an adhesive layer to bond the layers together and prevent the wax-free pad from delaminating.
[0007] However, during high-speed rotation in CMP polishing, the silicon wafer being polished generates heat. While the heat on the polishing pad is carried away by the polishing fluid, the heat in the center of the adsorption pad cannot be transferred away quickly. This results in the center of the adsorption pad having lower hardness than the surrounding area, leading to quality defects in the final polished product. Summary of the Invention
[0008] The purpose of this invention is to provide a wax-free pad for IC integrated circuits and its fabrication process, so as to solve the problems in the background art.
[0009] The objective of this invention can be achieved through the following technical solutions:
[0010] A wax-free pad for IC integrated circuits includes a support layer and an adsorption layer from the inside out.
[0011] The fabrication process for the wax-free pad used in IC integrated circuits includes the following steps:
[0012] Step 1: Lay 4-6 mesh fiberglass cloth flat in the mold, then melt modified polyurethane particles at 180-190℃ and coat them on the surface of the fiberglass cloth. After hot pressing, a substrate with a thickness of 0.3-0.5mm is obtained. The side of the substrate exposed on the fiberglass cloth is roughened to prepare the support layer.
[0013] Step 2: Lay out the support layer with the roughened side facing up, apply polyurethane prepolymer to the roughened side of the support layer, and after reaction and curing, obtain an adsorption layer with a thickness of 0.3-0.6mm. After cutting and shaping, prepare a wax-free pad for IC integrated circuits.
[0014] Furthermore, polyurethane prepolymers include polyurethane prepolymers generated by reacting polyethylene terephthalate and isocyanate as raw materials.
[0015] Furthermore, the modified polyurethane particles are prepared through the following steps:
[0016] Step S1: Mix ethylene carbonate and p-phenylenediamine and react at 60°C until no bubbles are generated. Then raise the temperature to 90°C and react for 3 hours. Remove unreacted raw materials by rotary evaporation. Pour the reaction product into a polytetrafluoroethylene mold, cool it, grind and pulverize it, and vacuum dry it at 60°C to obtain urethane-based diol.
[0017] Step S2: Hexamethylene diisocyanate and dibutyltin dilaurate were dissolved in N,N-dimethylacetamide under stirring at 80±5℃. Then, polytetrahydrofuran ether diol, 2,2-dimethylolbutyric acid and urethane diol were added after vacuum dehydration. The mixture was stirred and reacted at 80℃ under nitrogen protection for 3-4 hours. The temperature of the reaction system was lowered to 40℃, and then isophthalic acid dihydrazide solution was added to the reaction system. The mixture was stirred for 14-16 hours under nitrogen protection. The N,N-dimethylacetamide was removed by rotary evaporation at 80℃ to obtain polyurethane elastomer.
[0018] Step S3: After chopping the polyurethane elastomer, shear and mix it with the thermally conductive filler for 10-20 min, then melt mix it at 180±5℃ and 200-300 r / min for 10-15 min, and then extrude and granulate it using a twin-screw extruder to obtain modified polyurethane particles.
[0019] Furthermore, the ratio of ethylene carbonate to p-phenylenediamine is 50g:55g.
[0020] Furthermore, the ratio of the solutions of hexamethylene diisocyanate, dibutyltin dilaurate, N,N-dimethylacetamide, polytetrahydrofuran ether diol, 2,2-dimethylolbutyric acid, urethane diol, and isophthalic acid dihydrazide is 5.4 g: 0.02 g: 10 mL: 5 g: 1 g: 4 g: 60 mL.
[0021] Furthermore, the ratio of isophthalic acid dihydrazide to N,N-dimethylacetamide in the isophthalic acid dihydrazide solution is 1 g: 65 mL.
[0022] Furthermore, the ratio of polyurethane elastomer to thermally conductive filler is 100g: 25-30g.
[0023] Furthermore, the thermally conductive filler is prepared through the following steps:
[0024] Step 1: Disperse carbon nanotubes, anhydrous ethanol, polyvinyl alcohol and silane coupling agent by ultrasonication at 70-80℃ for 40-60 min, remove anhydrous ethanol by rotary evaporation, wash with deionized water 2-3 times, and vacuum dry at 60℃ to obtain modified carbon nanotubes.
[0025] Step 2: After ultrasonically dispersing the nano-aluminum nitride powder with anhydrous ethanol, aluminum dihydrogen phosphate and silane coupling agent are added. The mixture is ultrasonically dispersed for 60-80 min at 70-80℃. Then, polyvinyl alcohol is added and stirred for 1 h. The anhydrous ethanol is removed by rotary evaporation. The mixture is then washed 2-3 times with deionized water and vacuum dried at 60℃ to obtain modified aluminum nitride powder.
[0026] Step 3: Add the modified carbon nanotubes and modified aluminum nitride powder to acetone, using acetone as the dispersing liquid, and ultrasonically disperse for 10-20 minutes under ice bath conditions. Filter and dry to obtain the thermally conductive filler.
[0027] Furthermore, the ratio of carbon nanotubes, anhydrous ethanol, polyvinyl alcohol, and silane coupling agent is 50g:300mL:0.5-0.6g:0.1-0.3g.
[0028] Furthermore, the ratio of nano-aluminum nitride powder, anhydrous ethanol, aluminum dihydrogen phosphate, silane coupling agent and polyvinyl alcohol is 50g:300mL:1g:0.5-0.8g:0.1-0.3g.
[0029] Furthermore, the ratio of modified carbon nanotubes, modified aluminum nitride powder, and acetone is 1-2g: 1-1.5g: 10-15mL.
[0030] Furthermore, the silane coupling agent is silane coupling agent KH560 or silane coupling agent KH570.
[0031] The beneficial effects of this invention are:
[0032] The wax-free pads used in this invention for IC integrated circuits exhibit good mechanical properties and heat dissipation. During the preparation process, thermally conductive fillers are incorporated into the modified polyurethane particles. The nano-aluminum nitride powder and carbon nanotubes, after modification with a silane coupling agent, help improve their dispersion performance in the polyurethane elastomer and prevent the thermally conductive fillers from agglomerating. Polyvinyl alcohol helps improve the dispersion performance of both in anhydrous ethanol, thus enhancing the modification effect.
[0033] In the preparation of modified polyurethane particles, the raw materials contain large benzene ring rigid groups, which helps to improve the compression resistance of polyurethane particle materials. 2,2-dihydroxymethylbutyric acid containing carboxyl groups is introduced into the polyurethane backbone, followed by the addition of polar small molecule isophthalic acid dihydrazide. The acid-base relationship between the carboxyl group and the amino group forms ionic bonds, increasing the degree of hydrogen bonding and improving the tensile strength and hardness of the modified polyurethane particles, thus providing good support. The reaction of ethylene carbonate and p-phenylenediamine produces an urethane-based diol containing urethane groups. Combined with polytetrahydrofuran ether diol, this further enhances the hydrogen bonding of the hard segments of the polyurethane, increasing its melting temperature and resulting in better heat resistance of the modified polyurethane particle materials.
[0034] The support layer is composited with fiberglass cloth, which helps ensure that the wax-free pad has high tensile strength. The fiberglass cloth mesh also helps to ensure good contact between the adsorption layer material and the modified polyurethane material on the support layer, which helps to ensure the heat dissipation effect of the wax-free pad and keeps the rigidity of the wax-free pad consistent throughout, thereby preventing the flatness of the polished IC integrated circuit silicon wafer. Detailed Implementation
[0035] 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.
[0036] Example 1
[0037] This embodiment provides a thermally conductive filler, including the following implementation steps:
[0038] Step 1: 500g carbon nanotubes, 3L anhydrous ethanol, 5g polyvinyl alcohol and 1g silane coupling agent KH560 were ultrasonically dispersed at 70℃ for 40min, the anhydrous ethanol was removed by rotary evaporation, and then washed twice with deionized water and vacuum dried at 60℃ to obtain modified carbon nanotubes.
[0039] Step 2: Disperse 500g of nano aluminum nitride powder with 3L of anhydrous ethanol using ultrasonication, then add 10g of aluminum dihydrogen phosphate and 5g of silane coupling agent KH560. Continue ultrasonic dispersion at 70℃ for 60min, then add 1g of polyvinyl alcohol and stir for 1h. Remove the anhydrous ethanol by rotary evaporation, then wash twice with deionized water, and vacuum dry at 60℃ to obtain modified aluminum nitride powder.
[0040] Step 3: Add 200g of modified carbon nanotubes and 200g of modified aluminum nitride powder to 2L of acetone, using acetone as the dispersing liquid, and ultrasonically disperse for 10min under ice bath conditions. Filter and dry to obtain the thermally conductive filler.
[0041] Example 2
[0042] This embodiment provides a thermally conductive filler, including the following implementation steps:
[0043] Step 1: 500g carbon nanotubes, 3L anhydrous ethanol, 5.5g polyvinyl alcohol and 2g silane coupling agent KH570 were ultrasonically dispersed at 75℃ for 50min, the anhydrous ethanol was removed by rotary evaporation, and then washed three times with deionized water and vacuum dried at 60℃ to obtain modified carbon nanotubes.
[0044] Step 2: Disperse 500g of nano aluminum nitride powder with 3L of anhydrous ethanol using ultrasonication, then add 10g of aluminum dihydrogen phosphate and 6g of silane coupling agent KH570. Continue ultrasonic dispersion at 75℃ for 70min, then add 2g of polyvinyl alcohol and stir for 1h. Remove the anhydrous ethanol by rotary evaporation, then wash three times with deionized water, and vacuum dry at 60℃ to obtain modified aluminum nitride powder.
[0045] Step 3: Add 300g of modified carbon nanotubes and 250g of modified aluminum nitride powder to 2.5L of acetone, using acetone as the dispersing liquid, and ultrasonically disperse for 15min under ice bath conditions. Filter and dry to obtain the thermally conductive filler.
[0046] Example 3
[0047] This embodiment provides a thermally conductive filler, including the following implementation steps:
[0048] Step 1: 500g carbon nanotubes, 3L anhydrous ethanol, 6g polyvinyl alcohol and 3g silane coupling agent KH570 were ultrasonically dispersed at 80℃ for 60min, the anhydrous ethanol was removed by rotary evaporation, and then washed three times with deionized water and vacuum dried at 60℃ to obtain modified carbon nanotubes.
[0049] Step 2: After ultrasonically dispersing 500g of nano aluminum nitride powder with 3L of anhydrous ethanol, add 10g of aluminum dihydrogen phosphate and 8g of silane coupling agent KH570, and continue ultrasonic dispersion at 80℃ for 80min. Then add 3g of polyvinyl alcohol and stir for 1h. Remove the anhydrous ethanol by rotary evaporation, then wash three times with deionized water, and vacuum dry at 60℃ to obtain modified aluminum nitride powder.
[0050] Step 3: Add 400g of modified carbon nanotubes and 300g of modified aluminum nitride powder to 3L of acetone, using acetone as the dispersing liquid, and ultrasonically disperse for 20min under ice bath conditions. Filter and dry to obtain the thermally conductive filler.
[0051] Example 4
[0052] This embodiment provides a wax-free pad for IC integrated circuits, including the following specific implementation methods:
[0053] Step 1: Mix 50 kg of ethylene carbonate and 55 kg of p-phenylenediamine and react at 60°C until no bubbles are generated. Then raise the temperature to 90°C and react for 3 hours. Remove unreacted raw materials by rotary evaporation. Pour the reaction product into a polytetrafluoroethylene mold, cool it, grind and pulverize it, and vacuum dry it at 60°C to obtain urethane-based diol.
[0054] Step 2: Dissolve 10 kg of isophthalic acid dihydrazide in 650 L of N,N-dimethylacetamide to obtain an isophthalic acid dihydrazide solution; under conditions of 80±5℃, dissolve 54 kg of hexamethylene diisocyanate and 0.2 kg of dibutyltin dilaurate in 100 L of N,N-dimethylacetamide with stirring, then add 50 kg of polytetrahydrofuran ether glycol (after vacuum dehydration), 10 kg of 2,2-dimethylolbutyric acid, and 40 kg of urethane-based diol, and stir the reaction under nitrogen protection and at 80℃ for 3-4 h; lower the temperature of the reaction system to 40℃, then add 600 L of isophthalic acid dihydrazide solution to the reaction system, and stir under nitrogen protection for 14 h; then remove N,N-dimethylacetamide by rotary evaporation at 80℃ to obtain polyurethane elastomer.
[0055] Step 3: Chop 1 kg of polyurethane elastomer and shear mix it with 250 g of thermally conductive filler from Example 1 for 10 min. Then, melt mix it at 180±5℃ and 200 r / min for 10 min. Finally, extrude and granulate it using a twin-screw extruder to obtain modified polyurethane particles.
[0056] Step 4: Lay 6-mesh fiberglass cloth flat in the mold, then melt the modified polyurethane particles at 180°C and coat them onto the surface of the fiberglass cloth. After hot pressing, a substrate with a thickness of 0.3 mm is obtained. The side of the substrate exposed above the fiberglass cloth is roughened to prepare the support layer.
[0057] Step 5: Lay out the support layer with the roughened side facing up. Coat the roughened side of the support layer with polyurethane prepolymer. After the reaction and curing, an adsorption layer with a thickness of 0.3 mm is obtained. After cutting and shaping, a wax-free pad for IC integrated circuits is prepared. The polyurethane prepolymer is a polyurethane prepolymer generated by reacting polyethylene terephthalate and isocyanate as raw materials. The hardness and density of the wax-free pad adsorption layer can be adjusted according to the ratio of raw materials in the polyurethane prepolymer and the reaction control, which will not be elaborated here.
[0058] Example 5
[0059] This embodiment provides a wax-free pad for IC integrated circuits, including the following specific implementation methods:
[0060] Step 1: Mix 50 kg of ethylene carbonate and 55 kg of p-phenylenediamine and react at 60°C until no bubbles are generated. Then raise the temperature to 90°C and react for 3 hours. Remove unreacted raw materials by rotary evaporation. Pour the reaction product into a polytetrafluoroethylene mold, cool it, grind and pulverize it, and vacuum dry it at 60°C to obtain urethane-based diol.
[0061] Step 2: Dissolve 10 kg of isophthalic acid dihydrazide in 650 L of N,N-dimethylacetamide to obtain an isophthalic acid dihydrazide solution; under conditions of 80±5℃, dissolve 54 kg of hexamethylene diisocyanate and 0.2 kg of dibutyltin dilaurate in 100 L of N,N-dimethylacetamide with stirring, then add 50 kg of polytetrahydrofuran ether glycol (after vacuum dehydration), 10 kg of 2,2-dimethylolbutyric acid, and 40 kg of urethane-based diol, and stir the reaction under nitrogen protection and at 80℃ for 3.5 h; lower the temperature of the reaction system to 40℃, then add 600 L of isophthalic acid dihydrazide solution to the reaction system, stir under nitrogen protection for 15 h, and then remove N,N-dimethylacetamide by rotary evaporation at 80℃ to obtain polyurethane elastomer.
[0062] Step 3: Chop 1 kg of polyurethane elastomer and mix it with 280 g of thermally conductive filler from Example 2 by shearing for 15 min. Then, melt mix it at 180±5℃ and 250 r / min for 12 min. Finally, extrude and granulate it using a twin-screw extruder to obtain modified polyurethane particles.
[0063] Step 4: Lay 5-mesh fiberglass cloth flat in the mold, then melt the modified polyurethane particles at 185°C and coat them onto the surface of the fiberglass cloth. After hot pressing, a substrate with a thickness of 0.4 mm is obtained. The side of the substrate exposed above the fiberglass cloth is roughened to prepare the support layer.
[0064] Step 5: Lay out the support layer with the roughened side facing up. Apply a polyurethane prepolymer to the roughened side of the support layer. After the reaction and curing, an adsorption layer with a thickness of 0.5 mm is obtained. After cutting and shaping, a wax-free pad for IC integrated circuits is prepared. The polyurethane prepolymer is a polyurethane prepolymer generated by reacting polyethylene terephthalate and isocyanate as raw materials. The hardness and density of the wax-free pad adsorption layer can be adjusted according to the ratio of raw materials in the polyurethane prepolymer and the reaction control, which will not be elaborated here.
[0065] Example 6
[0066] This embodiment provides a wax-free pad for IC integrated circuits, including the following specific implementation methods:
[0067] Step 1: Mix 50 kg of ethylene carbonate and 55 kg of p-phenylenediamine and react at 60°C until no bubbles are generated. Then raise the temperature to 90°C and react for 3 hours. Remove unreacted raw materials by rotary evaporation. Pour the reaction product into a polytetrafluoroethylene mold, cool it, grind and pulverize it, and vacuum dry it at 60°C to obtain urethane-based diol.
[0068] Step 2: Dissolve 10 kg of isophthalic acid dihydrazide in 650 L of N,N-dimethylacetamide to obtain an isophthalic acid dihydrazide solution; under conditions of 80±5℃, dissolve 54 kg of hexamethylene diisocyanate and 0.2 kg of dibutyltin dilaurate in 100 L of N,N-dimethylacetamide by stirring, then add 50 kg of polytetrahydrofuran ether glycol (after vacuum dehydration), 10 kg of 2,2-dimethylolbutyric acid, and 40 kg of urethane-based diol, and stir the reaction under nitrogen protection and at 80℃ for 4 h; lower the temperature of the reaction system to 40℃, then add 600 L of isophthalic acid dihydrazide solution to the reaction system, and stir under nitrogen protection for 16 h; then remove N,N-dimethylacetamide by rotary evaporation at 80℃ to obtain polyurethane elastomer.
[0069] Step 3: Chop 1 kg of polyurethane elastomer and mix it with 300 g of thermally conductive filler from Example 3 by shearing for 20 min. Then, melt mix it at 180±5℃ and 300 r / min for 15 min. Finally, extrude and granulate it using a twin-screw extruder to obtain modified polyurethane particles.
[0070] Step 4: Lay 4-mesh fiberglass cloth flat in the mold, then melt the modified polyurethane particles at 190°C and coat them on the surface of the fiberglass cloth. After hot pressing, a substrate with a thickness of 0.5 mm is obtained. The side of the substrate exposed on the fiberglass cloth is roughened to prepare the support layer.
[0071] Step 5: Lay out the support layer with the roughened side facing up. Coat the roughened side of the support layer with polyurethane prepolymer. After the reaction and curing, an adsorption layer with a thickness of 0.6 mm is obtained. After cutting and shaping, a wax-free pad for IC integrated circuits is prepared. The polyurethane prepolymer is a polyurethane prepolymer generated by reacting polyethylene terephthalate and isocyanate as raw materials. The hardness and density of the wax-free pad adsorption layer can be adjusted according to the ratio of raw materials in the polyurethane prepolymer and the reaction control, which will not be elaborated here.
[0072] Comparative Example 1: Based on Example 3, 700g of the modified aluminum nitride powder from Example 3 was directly added to 3L of acetone, ultrasonically dispersed for 20min under ice bath conditions, filtered, and dried to obtain a thermally conductive filler; using this thermally conductive filler, a wax-free pad was prepared according to the method of Example 6.
[0073] Comparative Example 2: Based on Example 6, 1 kg of polyurethane elastomer was directly chopped and melted at 180±5℃ and 300 r / min for 15 min. Then, polyurethane particles were prepared by extrusion granulation using a twin-screw extruder. The modified polyurethane particles were replaced with these polyurethane particles, and the remaining steps remained unchanged to prepare a wax-free pad.
[0074] Comparative Example 3: Based on Example 6, the urethane-based diol was replaced with the same mass of polytetrahydrofuran ether diol. Wax-free pads were prepared by adding only 60 kg of polytetrahydrofuran ether diol and 10 kg of 2,2-dihydroxymethylbutyric acid, while keeping the other steps unchanged.
[0075] The carbon nanotubes were purchased from Hebei Moyu Chemical Co., Ltd., with the product number CN300; the nano aluminum nitride was purchased from Yumu (Ningbo) New Materials Co., Ltd., with the MDL number MFCD00003429; and the polytetrahydrofuran ether diol used had a molecular weight of 1000.
[0076] Performance tests were conducted on Examples 4-6 and Comparative Examples 1-3. According to GB / T528—2009, the tensile strength and elongation at break of different unwaxed pads were tested using an electronic universal testing machine (tensile speed 200 mm / min, average value of 5 samples per group). Different unwaxed pads were cut into circular pieces with a diameter of 2 cm and heated to 100°C using a thermal conductivity tester. The temperature difference T over 20 minutes was measured (the thermal conductivity tester consisted of three parts: a constant heat source, a heat transfer section, and a heat transfer component). The temperature measurement section is as follows: The constant heat source is a constant-pressure, constant-current heat source that provides constant power. The heat transfer section consists of thermoelectric ceramics, graphite sheets, and a copper column. It does not lose heat during the heat transfer process and is surrounded by insulating cotton for insulation. The temperature measurement section consists of a thermocouple thermometer and two probes. One probe detects the temperature at the center of the copper column (T1), and the other probe detects the temperature at the center of the disc (T2). The temperature is then displayed by the thermometer. The heat dissipation effect is compared by the temperature difference between T1 and T2 (the larger the temperature difference, the better the heat dissipation effect). The results are shown in Table 1.
[0077] Table 1
[0078]
[0079]
[0080] As can be seen from Table 1, the wax-free pads in Examples 4-6 of this application have good tensile strength and good heat dissipation effect. As can be seen from Comparative Documents 1-2, modified carbon nanotubes help to synergistically improve the heat dissipation effect. As can be seen from Comparative Document 3, urethane-based diols help to improve the tensile strength of the wax-free pads.
[0081] It should be noted that, in this document, terms such as “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.
[0082] 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 process for fabricating a wax-free pad for IC integrated circuits, characterized in that, Includes the following steps: Step 1: Melt the modified polyurethane particles at 180-190℃ and coat them onto the surface of 4-6 mesh fiberglass cloth. After hot pressing, a substrate with a thickness of 0.3-0.5mm is obtained. The side of the substrate exposed on the fiberglass cloth is roughened to obtain the support layer. Step 2: Lay out the support layer and coat the roughened side of the support layer with polyurethane prepolymer. After the reaction and curing, an adsorption layer with a thickness of 0.3-0.6 mm is obtained. After cutting and shaping, a wax-free pad for IC integrated circuits is prepared. Modified polyurethane particles are prepared through the following steps: The polyurethane elastomer was shredded and sheared and mixed with thermally conductive filler for 10-20 min. Then, it was melt-mixed for 10-15 min at 180±5℃ and 200-300 r / min, and then extruded and granulated to obtain modified polyurethane particles.
2. The fabrication process of a wax-free pad for IC integrated circuits according to claim 1, characterized in that, The ratio of polyurethane elastomer to thermally conductive filler is 100g: 25-30g.
3. The fabrication process of a wax-free pad for IC integrated circuits according to claim 1, characterized in that, The polyurethane elastomer is prepared by the following steps: Hexamethylene diisocyanate and dibutyltin dilaurate were dissolved in N,N-dimethylacetamide under stirring at 80±5℃. Polytetrahydrofuran ether diol, 2,2-dimethylolbutyric acid and urethane diol were added and stirred at 80℃ for 3-4 hours under nitrogen protection. The mixture was then cooled to 40℃, and isophthalic acid dihydrazide solution was added to the reaction system and stirred for 14-16 hours under nitrogen protection. The mixture was then rotary evaporated to obtain polyurethane elastomer.
4. The fabrication process of a wax-free pad for IC integrated circuits according to claim 3, characterized in that, The ratio of the hexamethylene diisocyanate, dibutyltin dilaurate, N,N-dimethylacetamide, polytetrahydrofuran ether diol, 2,2-dimethylolbutyric acid, urethane diol, and isophthalic acid dihydrazide solution is 5.4g:0.02g:10mL:5g:1g:4g:60mL.
5. The fabrication process of a wax-free pad for IC integrated circuits according to claim 4, characterized in that, The urethane-type diol is prepared by the following steps: Ethylene carbonate and p-phenylenediamine were stirred and mixed, and reacted at 60°C until no bubbles were generated. Then the temperature was increased to 90°C and reacted for 3 hours. The mixture was then rotary evaporated, cooled, ground, and vacuum dried to obtain an urethane-based diol.
6. The fabrication process of a wax-free pad for IC integrated circuits according to claim 5, characterized in that, The ratio of ethylene carbonate to p-phenylenediamine is 50g:55g.
7. The fabrication process of a wax-free pad for IC integrated circuits according to claim 1, characterized in that, The thermally conductive filler is prepared by the following steps: Step 1: Carbon nanotubes, anhydrous ethanol, polyvinyl alcohol, and silane coupling agent are ultrasonically dispersed at 70-80℃ for 40-60 min, followed by rotary evaporation, washing, and vacuum drying to obtain modified carbon nanotubes; nano-aluminum nitride powder, anhydrous ethanol, aluminum dihydrogen phosphate, and silane coupling agent are ultrasonically dispersed at 70-80℃ for 60-80 min, then polyvinyl alcohol is added and stirred for 1 h, followed by rotary evaporation, washing, and vacuum drying to obtain modified aluminum nitride powder; Step 2: The modified carbon nanotubes, modified aluminum nitride powder and acetone are ultrasonically dispersed in an ice bath for 10-20 minutes, filtered and dried to obtain the thermally conductive filler.
8. The fabrication process of a wax-free pad for IC integrated circuits according to claim 7, characterized in that, The ratio of the modified carbon nanotubes, modified aluminum nitride powder and acetone is 1-2g: 1-1.5g: 10-15mL.
9. The fabrication process of a wax-free pad for IC integrated circuits according to claim 7, characterized in that, The silane coupling agent is silane coupling agent KH560 or silane coupling agent KH570.
10. A wax-free pad for IC integrated circuits, characterized in that, It is prepared by any one of the preparation processes in claims 1-9.