Chemical mechanical polishing liquid for soft magnetic alloy and polishing method

Abstract

The application discloses a chemical mechanical polishing liquid and a polishing method for soft magnetic alloy. The polishing liquid is composed of the following raw material components in percentage by weight: 1.3wt%-1.8wt% of a chelating agent, 10wt%-13wt% of abrasive, 7wt%-9wt% of a pH buffer, 3wt%-3.5wt% of a corrosion inhibitor, 11wt%-13wt% of an oxidizing agent and the balance of deionized water. The abrasive is acidic silica sol, the oxidizing agent is hydrogen peroxide, the corrosion inhibitor is at least one of glycine, polyaspartic acid, glutamic acid and chitosan, the pH of the polishing liquid is 3-5, and the pH buffer is a citric acid-sodium citrate buffer. The polishing method comprises the following steps: grinding the soft magnetic alloy; performing chemical mechanical polishing rough polishing on the ground soft magnetic alloy by using a rough polishing slurry; performing chemical mechanical polishing fine polishing on the rough polished soft magnetic alloy by using the polishing liquid, so that the soft magnetic alloy with a smooth and flat surface is obtained. The polishing liquid is green, environment-friendly and pollution-free, and the surface of the soft magnetic alloy after polishing is smooth and flat.

Description

Technical Field

[0001] This invention belongs to the technical field of metal processing, and particularly relates to a chemical mechanical polishing slurry and polishing method for soft magnetic alloys. Background Technology

[0002] Soft magnetic alloys are mainly composed of elements such as iron (Fe), chromium (Cr), silicon (Si), and aluminum (Al). Due to their excellent properties such as high permeability, low coercivity, and low hysteresis loss, they occupy an indispensable position in many key fields such as electronic information, power transmission, aerospace, and precision instrument manufacturing. They are key materials for various precision instruments and navigation equipment, motors, sensors, magnetic recording heads, and other devices. With the continuous advancement of technology, the requirements for the surface quality and precision of soft magnetic alloys are increasing. Surface quality directly affects the magnetic properties, corrosion resistance, and service life of soft magnetic alloys.

[0003] Chemical mechanical polishing (CMP) is an ultra-precision machining process that combines chemical reactions and mechanical removal. Through the coupling effect between the polishing pad, polishing slurry and workpiece, the workpiece surface is continuously finished. It can effectively remove micro-defects on the workpiece surface, reduce surface roughness and improve surface smoothness, thereby meeting the stringent requirements of soft magnetic alloys in high-end applications.

[0004] As a core component of chemical mechanical polishing (CMP) technology, the performance of polishing slurries directly determines the quality, efficiency, and environmental friendliness of material surface processing. Traditional CMP processes typically use polishing slurries containing large amounts of chemical reagents, such as strong oxidants, acids, and alkalis. If these chemicals are discharged directly after polishing without proper treatment, they can cause serious pollution to the soil, water bodies, and other natural environments. Furthermore, traditional polishing slurries and methods often fail to achieve ideal surface roughness and smoothness when polishing soft magnetic alloys. Summary of the Invention

[0005] The purpose of this invention is to solve at least one problem in the prior art by providing a chemical mechanical polishing slurry and polishing method for soft magnetic alloys.

[0006] To achieve the above objectives, this invention provides a chemical mechanical polishing slurry for soft magnetic alloys, wherein the slurry comprises the following raw material components in weight percentage: 1.3wt%–1.8wt% chelating agent, 10wt%–13wt% abrasive, 7wt%–9wt% pH buffer, 3wt%–3.5wt% corrosion inhibitor, 11wt%–13wt% oxidant, and the balance being deionized water. The abrasive is acidic silica sol, the oxidant is hydrogen peroxide, and the corrosion inhibitor is at least one selected from glycine, polyaspartic acid, glutamic acid, and chitosan. The pH of the slurry is 3–5, and the pH buffer is a citrate-sodium citrate buffer solution.

[0007] As an optional implementation, the chelating agent is oxalic acid or humic acid.

[0008] As an optional implementation, the content of silicon dioxide in the acidic silica sol is 30%, and the particle size of the acidic silica sol is 10nm to 20nm.

[0009] As an optional embodiment, the citric acid-sodium citrate buffer solution is prepared by mixing citric acid and sodium citrate in a mass ratio of (0.5-1.5):(2-4). The mass ratio of citric acid to sodium citrate in the citric acid-sodium citrate buffer solution can be (0.5:2), (0.5:4), (1:2), or (1:3), and can be configured according to the pH adjustment requirements and the content of other components in the polishing solution.

[0010] As an optional implementation, the citric acid-sodium citrate buffer solution is prepared by mixing citric acid and sodium citrate in a mass ratio of 1:3.

[0011] As an optional implementation, the polishing liquid is prepared by mixing the various raw material components, subjecting them to ultrasonic vibration treatment, and stirring to form a uniform and stable suspension.

[0012] This invention also proposes a polishing method for polishing soft magnetic alloys, comprising the following steps:

[0013] The soft magnetic alloy is ground to remove deep scratches from its surface;

[0014] The soft magnetic alloy after grinding was subjected to chemical mechanical polishing (CMP) to reduce the surface roughness of the soft magnetic alloy to the submicron level. The CMP process is as follows: the polishing disc speed is 60 rpm to 90 rpm, the flow rate of the polishing fluid is 10 mL / min to 15 mL / min, the polishing pressure is 30 kPa to 40 kPa, and the polishing time is 40 min to 60 min. After polishing, the surface of the soft magnetic alloy is cleaned and dried.

[0015] The soft magnetic alloy after rough polishing is subjected to chemical mechanical polishing (CMP) to obtain a soft magnetic alloy with a smooth and flat surface by using the polishing slurry described in any one of claims 1 to 6. The polishing process for fine polishing is as follows: the polishing disc rotation speed is 60 rpm to 80 rpm, the flow rate of the polishing slurry is 3 mL / min to 5 mL / min, the polishing pressure is 30 kPa to 40 kPa, and the polishing time is 40 min to 60 min. After polishing, the surface of the soft magnetic alloy is cleaned and dried.

[0016] As an optional implementation, the coarse polishing slurry is prepared by mixing hydrogen peroxide, acidic silica sol, cerium oxide and deionized water.

[0017] As an optional implementation, the grinding is performed using 2000-4000 grit sandpaper, and the polishing pad used in the chemical mechanical polishing process is made of frosted leather. The grit of the sandpaper can be selected according to the required grinding roughness, and can be 2000 grit, 2500 grit, 3000 grit, or 4000 grit.

[0018] As an optional implementation, the surface of the polished soft magnetic alloy is cleaned sequentially with deionized water and anhydrous ethanol, and then dried with compressed air. The Sa value of the finely polished soft magnetic alloy is 0.104nm to 0.123nm.

[0019] Introduction to the working mechanism of polishing slurry and soft magnetic alloy in CMP process:

[0020] In soft magnetic alloys, the metallic elements Al, Cr, and Fe are oxidized by H₂O₂, forming an oxide layer on the metal surface. + The oxides of Fe dissolved, while the oxides of Cr and Al hardly dissolved, resulting in Fe... 2+ and Fe 3+ Released into the slurry, the oxides generated in CMP are continuously removed through mechanical action, improving surface defects and ultimately forming an ultra-smooth surface of the soft magnetic alloy. The nano-sized SiO2 particles in the acidic silica sol are mechanically ground, removing the surface oxide layer and metal debris through physical friction, thus providing a basic smoothness. Furthermore, the acidic environment of the sol (pH 3.5) inhibits particle agglomeration, ensuring uniform grinding and guaranteeing dispersion stability. The chelating agent participates in the reaction, dissolving Fe through chelation. 3+ It forms soluble complexes, accelerating metal dissolution; on the other hand, its weak reducing properties can partially reduce Cr. 6+ For Cr 3+ To avoid Cr 6+ Toxic oxides hinder the reaction; corrosion inhibitors such as glycine can form an adsorption film on the metal surface, effectively preventing direct contact between the metal and the corrosive medium, slowing down the corrosion rate of the metal, and reducing the wear and tear on the equipment while ensuring the smooth progress of the reaction.

[0021] Introduction to the effects of the components in the polishing slurry:

[0022] The high-hardness silica particles in acidic silica sol provide efficient grinding capabilities, ensuring polishing efficiency and effectiveness; the nanoscale monodisperse particle size enables uniform surface removal, avoiding local over-polishing or under-polishing; the low coefficient of friction, combined with dynamic lubrication, significantly reduces surface scratches and damage; and the low surface activity allows it to remain stably dispersed in acidic environments, extending abrasive lifespan and reducing replacement frequency.

[0023] Hydrogen peroxide, as an oxidant, possesses strong oxidizing properties. Through oxidative corrosion, it oxidizes the metal surface into higher-valence oxides, increasing the chemical dissolution rate. Furthermore, it can form a dense oxide film, which is then synergistically exfoliated by hydrogen peroxide and chelating agents, achieving dynamic oxide layer control, balancing passivation and corrosion, and improving the removal rate of impurities and defects on the metal surface. This results in improved surface quality of the polished metal. Moreover, hydrogen peroxide is low in cost and produces non-polluting byproducts, making it a green and environmentally friendly oxidant.

[0024] Chelating agents can chelate with some metal ions in soft magnetic alloys, promoting the dissolution of the material. Oxalic acid or humic acid are preferred chelating agents. Oxalic acid and humic acid are non-toxic, harmless, and environmentally friendly, and can prevent metal ions from polluting the environment.

[0025] Corrosion inhibitors can effectively suppress excessive corrosion and protect the surface of soft magnetic alloys. Glycine, polyaspartic acid, glutamic acid, and chitosan are preferred because they are green and environmentally friendly.

[0026] The preferred pH buffer is a citrate-sodium citrate buffer solution, which is environmentally friendly and can replace traditional strong acid reagents. It provides a stable acidic environment for the polishing process, reducing environmental harm and allowing for more precise control of the chemical reaction rate. Through pH control, it maintains the polishing solution at a pH of 3-5, ensuring the chelating activity of the chelating agent while inhibiting the rapid decomposition of hydrogen peroxide. It also plays a crucial role in pH buffering, effectively resisting the influence of small amounts of external acid or alkali on the system's pH value, ensuring a relatively stable reaction environment, and providing suitable and stable acid-base conditions for the entire reaction process.

[0027] The beneficial effects of this invention are as follows: By using a special ratio of chelating agent, abrasive, pH buffer, corrosion inhibitor, and oxidant, and with a polishing solution pH of 3-5, the components work synergistically to improve the polishing effect of the polishing solution on soft magnetic alloys, remove microscopic defects on the surface of the soft magnetic alloys, and make the surface of the soft magnetic alloys smooth and flat with low roughness after polishing. All components in the polishing solution are selected from green, environmentally friendly, and pollution-free reagents, so that the polishing solution will not cause pollution to the environment after polishing, and the preparation process is simple. The polishing method combines grinding, chemical mechanical polishing, rough polishing, and fine polishing to achieve atomic-level removal and flattening of the soft magnetic alloy surface, thereby preparing a nearly damage-free ultra-smooth surface.

[0028] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0029] Figure 1 This is a diagram showing the surface roughness and morphology of the soft magnetic alloy obtained in Example 1 of this application.

[0030] Figure 2The images show the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 1 of this application.

[0031] Figure 3 The image shows the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 2 of this application.

[0032] Figure 4 The image shows the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 3 of this application.

[0033] Figure 5 The image shows the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 4 of this application.

[0034] Figure 6 The image shows the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 5 of this application.

[0035] Figure 7 The images show the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 6 of this application.

[0036] Figure 8 The image shows the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 7 of this application.

[0037] Figure 9 The image shows the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 8 of this application.

[0038] Figure 10 The image shows the surface roughness and morphology of the soft magnetic alloy obtained in Comparative Example 9 of this application. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0040] The present invention will now be described in detail with reference to the accompanying drawings.

[0041] Example 1

[0042] This embodiment provides a chemical mechanical polishing slurry for soft magnetic alloys, which is composed of the following raw material components by weight percentage: 1.6 wt% oxalic acid, 11 wt% acidic silica sol, 8 wt% citric acid-sodium citrate buffer, 3.2 wt% glycine, 12 wt% hydrogen peroxide, and the balance being deionized water. The pH of the polishing slurry is 3.5, the silica content in the acidic silica sol is 30%, and the citric acid-sodium citrate buffer is composed of citric acid and sodium citrate mixed in a mass ratio of 1:3.

[0043] This embodiment also provides a polishing method for polishing soft magnetic alloys, comprising the following steps:

[0044] The soft magnetic alloy was ground with 3000-grit sandpaper for 2 minutes to remove deep scratches on its surface. After grinding, the surface was cleaned with deionized water and anhydrous ethanol in turn and then dried with compressed air.

[0045] The soft magnetic alloy after grinding was subjected to chemical mechanical polishing (CMP) to reduce the surface roughness to the submicron level using a coarse polishing slurry. The coarse polishing slurry was prepared by mixing 2 wt% hydrogen peroxide, 6 wt% acidic silica sol (30%), 1.25 wt% cerium oxide, and the balance deionized water. The coarse polishing process was as follows: the polishing disc speed was 80 rpm, the flow rate of the polishing fluid was 10 mL / min, the polishing pressure was 38.9 kPa, and the polishing time was 40 min. Magnetic stirring was used during the polishing process to maintain the uniformity of the coarse polishing slurry. After polishing, the surface of the soft magnetic alloy was cleaned with deionized water and anhydrous ethanol in sequence, and then dried with compressed air.

[0046] The soft magnetic alloy after rough polishing was subjected to chemical mechanical polishing (CMP) to achieve a smooth surface. The polishing process was as follows: the polishing disc speed was 60 rpm, the flow rate of the polishing fluid was 5 mL / min, the polishing pressure was 38.9 kPa, and the polishing time was 45 min. Magnetic stirring was used during the polishing process to maintain the uniformity of the polishing fluid. After polishing, the surface of the soft magnetic alloy was cleaned with deionized water and anhydrous ethanol in sequence, and then dried with compressed air.

[0047] The surface roughness and morphology of the finely polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 1 The detection range is 50×50μm 2 Under these conditions, the soft magnetic alloy polished by the polishing method of this application has a minimum surface roughness Sa of 0.104 nm, and the surface is smooth with no obvious protrusions.

[0048] Example 2

[0049] This embodiment provides a chemical mechanical polishing slurry for soft magnetic alloys, which is composed of the following raw material components by weight percentage: 1.3 wt% humic acid, 10 wt% acidic silica sol, 7 wt% citric acid-sodium citrate buffer, 3 wt% glutamic acid, 11 wt% hydrogen peroxide, and the balance being deionized water. The pH of the polishing slurry is 4, the silica content in the acidic silica sol is 25%, and the citric acid-sodium citrate buffer is composed of citric acid and sodium citrate mixed in a mass ratio of 1:2.

[0050] This embodiment also provides a polishing method for polishing soft magnetic alloys, comprising the following steps:

[0051] The soft magnetic alloy was ground with 2500-grit sandpaper for 3 minutes to remove deep scratches on its surface. After grinding, the surface was cleaned with deionized water and anhydrous ethanol in turn and then dried with compressed air.

[0052] The soft magnetic alloy after grinding was subjected to chemical mechanical polishing (CMP) to reduce the surface roughness to the submicron level. The CMP was prepared by mixing 4 wt% hydrogen peroxide, 8 wt% acidic silica sol (30%), 1.5 wt% cerium oxide, and the balance deionized water. The CMP process was as follows: the polishing disc speed was 60 rpm, the polishing fluid flow rate was 12 mL / min, the polishing pressure was 30 kPa, and the polishing time was 50 min. Magnetic stirring was used during the polishing process to maintain the uniformity of the CMP. After polishing, the surface of the soft magnetic alloy was cleaned with deionized water and anhydrous ethanol in sequence, and then dried with compressed air.

[0053] The soft magnetic alloy after rough polishing was subjected to chemical mechanical polishing (CMP) to achieve a smooth surface. The polishing process was as follows: the polishing disc rotation speed was 70 rpm, the flow rate of the polishing fluid was 3 mL / min, the polishing pressure was 30 kPa, and the polishing time was 40 min. Magnetic stirring was used during the polishing process to maintain the uniformity of the polishing fluid. After polishing, the surface of the soft magnetic alloy was cleaned with deionized water and anhydrous ethanol in sequence, and then dried with compressed air.

[0054] The surface roughness and morphology of the soft magnetic alloy after fine polishing were inspected using a 3D surface optical profilometer (NewView 9000, Zygo Corporation, USA). The soft magnetic alloy polished by the polishing method of this application had a minimum surface roughness Sa of 0.108 nm, and the surface was smooth with no obvious protrusions.

[0055] Example 3

[0056] This embodiment provides a chemical mechanical polishing slurry for soft magnetic alloys, which is composed of the following raw material components by weight percentage: 0.7 wt% humic acid, 1.1% oxalic acid, 13 wt% acidic silica sol, 9 wt% citric acid-sodium citrate buffer, 1 wt% glutamic acid, 1.5% glycine, 11 wt% hydrogen peroxide, and the balance being deionized water. The pH of the polishing slurry is 3, the silica content in the acidic silica sol is 30%, and the citric acid-sodium citrate buffer is composed of citric acid and sodium citrate mixed in a mass ratio of 1:3.

[0057] This embodiment also provides a polishing method for polishing soft magnetic alloys, comprising the following steps:

[0058] The soft magnetic alloy was ground with 4000-grit sandpaper for 5 minutes to remove deep scratches on its surface. After grinding, the surface was cleaned with deionized water and anhydrous ethanol in turn and then dried with compressed air.

[0059] The soft magnetic alloy after grinding was subjected to chemical mechanical polishing (CMP) to reduce the surface roughness to the submicron level using a coarse polishing slurry. The coarse polishing slurry was prepared by mixing 3 wt% hydrogen peroxide, 10 wt% acidic silica sol (30%), 1.8 wt% cerium oxide, and the balance deionized water. The coarse polishing process was as follows: the polishing disc speed was 70 rpm, the flow rate of the polishing fluid was 15 mL / min, the polishing pressure was 40 kPa, and the polishing time was 60 min. Magnetic stirring was used during the polishing process to maintain the uniformity of the coarse polishing slurry. After polishing, the surface of the soft magnetic alloy was cleaned with deionized water and anhydrous ethanol in sequence, and then dried with compressed air.

[0060] The soft magnetic alloy after rough polishing was subjected to chemical mechanical polishing (CMP) to achieve a smooth surface. The polishing process was as follows: the polishing disc rotation speed was 80 rpm, the polishing fluid flow rate was 4.5 mL / min, the polishing pressure was 40 kPa, and the polishing time was 40 min. Magnetic stirring was used during the polishing process to maintain the uniformity of the polishing fluid. After polishing, the surface of the soft magnetic alloy was cleaned with deionized water and anhydrous ethanol in sequence, and then dried with compressed air.

[0061] The surface roughness and morphology of the soft magnetic alloy after fine polishing were inspected using a 3D surface optical profilometer (NewView 9000, Zygo Corporation, USA). The soft magnetic alloy polished by the polishing method of this application had a minimum surface roughness Sa of 0.106 nm, and the surface was smooth with no obvious protrusions.

[0062] Compare with Example 1

[0063] This comparative example uses a single grinding method to process the surface of the soft magnetic alloy. The specific grinding method is as follows: the soft magnetic alloy is ground with 3000-grit sandpaper for 2 minutes. After grinding, the surface is cleaned with deionized water and anhydrous ethanol in sequence and then dried with compressed air.

[0064] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 2 The detection range is 50×50μm 2 In this case, the lowest surface roughness Sa of the soft magnetic alloy after grinding is 42.260 nm, and there are a lot of scratches and protrusions on the surface.

[0065] Compare with Example 2

[0066] This comparative example uses a single chemical mechanical polishing (CMP) method to process the surface of a soft magnetic alloy. The specific polishing method is as follows: The soft magnetic alloy is chemically mechanically polished using a polishing slurry. The polishing slurry is prepared by mixing 2 wt% hydrogen peroxide, 6 wt% acidic silica sol (30%), and 1.25 wt% cerium oxide with the balance deionized water. The polishing process is as follows: the polishing disc speed is 80 rpm, the polishing fluid flow rate is 10 mL / min, the polishing pressure is 38.9 kPa, and the polishing time is 40 min. During the polishing process, magnetic stirring is used to maintain the uniformity of the coarse polishing slurry. After polishing, the surface of the soft magnetic alloy is cleaned sequentially with deionized water and anhydrous ethanol, and then dried with compressed air.

[0067] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 3 The detection range is 50×50μm 2 In this case, the lowest surface roughness Sa of the soft magnetic alloy is 1.808 nm, and the surface has pits and scratches with obvious protrusions.

[0068] Compare with Example 3

[0069] The polishing solution of this comparative example is the same as that of Example 1, except that the weight percentage of hydrogen peroxide in the components is adjusted to 8 wt% and the weight percentage of deionized water is increased accordingly. The same polishing method as that of Example 1 is used to treat the soft magnetic alloy surface.

[0070] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 4 The detection range is 50×50μm 2 In this case, the lowest surface roughness Sa of the soft magnetic alloy is 0.109 nm, and there are a few small pits on the surface.

[0071] Compare with Example 4

[0072] The polishing solution in this comparative example is identical to the polishing solution in Example 1, except that the weight percentage of hydrogen peroxide in the components is adjusted to 0 wt% and the weight percentage of deionized water is increased accordingly. The same polishing method as in Example 1 is used to treat the soft magnetic alloy surface.

[0073] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 5 The detection range is 50×50μm 2In this case, the lowest surface roughness Sa of the soft magnetic alloy is 0.224 nm, and small pits exist on the surface.

[0074] Compare with Example 5

[0075] The polishing solution in this comparative example is identical to the polishing solution in Example 1, except that the weight percentage of hydrogen peroxide in the components is adjusted to 4 wt% and the weight percentage of deionized water is increased accordingly. The same polishing method as in Example 1 is used to treat the soft magnetic alloy surface.

[0076] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 6 The detection range is 50×50μm 2 In this case, the lowest surface roughness Sa of the soft magnetic alloy is 0.129 nm, and there are a few small pits on the surface.

[0077] Compare with Example 6

[0078] The polishing solution in this comparative example is identical to the polishing solution in Example 1, except that the weight percentage of hydrogen peroxide in the components is adjusted to 16 wt% and the weight percentage of deionized water is reduced accordingly. The same polishing method as in Example 1 is used to treat the soft magnetic alloy surface.

[0079] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 7 The detection range is 50×50μm 2 Under these conditions, the lowest surface roughness Sa of the soft magnetic alloy is 0.230 nm, the surface is smooth and there are no obvious protrusions.

[0080] Compare with Example 7

[0081] The polishing solution in this comparative example is identical to the polishing solution in Example 1, except that the weight percentage of glycine in the components is adjusted to 0 wt% and the weight percentage of deionized water is increased accordingly. The same polishing method as in Example 1 is used to treat the soft magnetic alloy surface.

[0082] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo Corporation, USA). See Figure 8; the inspection range was 50 × 50 μm. 2 In this case, the lowest surface roughness Sa of the soft magnetic alloy is 0.164 nm, and the surface has scratches and small pits.

[0083] Compare with Example 8

[0084] The polishing solution of this comparative example is the same as that of Example 1, except that the weight percentage of glycine in the components is adjusted to 1.6 wt% and the weight percentage of deionized water is increased accordingly. The same polishing method as that of Example 1 is used to treat the soft magnetic alloy surface.

[0085] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 9 The detection range is 50×50μm 2 In this case, the lowest surface roughness Sa of the soft magnetic alloy is 0.190 nm, and there are a few scratches and small pits on the surface.

[0086] Compare with Example 9

[0087] The polishing solution of this comparative example is the same as that of Example 1, except that the weight percentage of glycine in the components is adjusted to 4.8 wt% and the weight percentage of deionized water is reduced accordingly. The same polishing method as that of Example 1 is used to treat the soft magnetic alloy surface.

[0088] The surface roughness and morphology of the polished soft magnetic alloy were inspected using a 3D surface optical profilometer (NewView 9000, Zygo, USA). See also... Figure 10 The detection range is 50×50μm 2 In this case, the lowest surface roughness Sa of the soft magnetic alloy is 0.143 nm, and there are some small pits on the surface.

[0089] Based on the comparison of the lowest surface roughness and surface morphology of the soft magnetic alloys in Example 1 and the comparative examples, it can be seen that compared with the single grinding treatment in Comparative Example 1, the grinding + chemical mechanical polishing treatment in Comparative Example 2, and the single chemical mechanical polishing treatment in Comparative Example 3, the grinding method of Example 1 can achieve a lower surface roughness and a smoother and flatter surface. Combining grinding, chemical mechanical polishing, and chemical mechanical polishing, grinding removes deep scratches on the metal surface, and then chemical mechanical polishing further reduces scratches, pits, and other defects, reducing the initial roughness from the micrometer level to the submicrometer level to obtain a surface of a certain quality. Finally, chemical mechanical polishing, through the dynamic balance between chemical corrosion and mechanical grinding, achieves atomic-level removal and smoothing of the soft magnetic alloy surface, thereby preparing a nearly damage-free ultra-smooth surface.

[0090] Experiments revealed that the selection of each component and its proportion in the polishing slurry of this application affects the subsequent polishing effect on soft magnetic alloys, making it difficult to simultaneously achieve the desired polishing effect of the polishing slurry on the surface smoothness and roughness of the soft magnetic alloy. Specific experimental results are shown in Example 1 and Comparative Examples 3-9. The optimal polishing slurry formulation was obtained by controlling the content of corrosion inhibitors and oxidants in the polishing slurry through single-factor experiments.

[0091] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.

Claims

1. A chemical mechanical polishing slurry for soft magnetic alloys, characterized in that, The polishing slurry is composed of the following raw material components in weight percentage: chelating agent 1.3wt% to 1.8wt%, abrasive 10wt% to 13wt%, pH buffer 7wt% to 9wt%, corrosion inhibitor 3wt% to 3.5wt%, oxidant 11wt% to 13wt%, and the balance being deionized water. The abrasive is acidic silica sol, the oxidant is hydrogen peroxide, and the corrosion inhibitor is at least one selected from glycine, polyaspartic acid, glutamic acid, and chitosan. The pH of the polishing slurry is 3 to 5, and the pH buffer is a citrate-sodium citrate buffer solution.

2. The chemical mechanical polishing slurry for soft magnetic alloys as described in claim 1, characterized in that: The chelating agent is oxalic acid or humic acid.

3. The chemical mechanical polishing slurry for soft magnetic alloys as described in claim 1, characterized in that: The acidic silica sol contains 30% silica and has a particle size of 10 nm to 20 nm.

4. The chemical mechanical polishing slurry for soft magnetic alloys as described in claim 1, characterized in that: The citric acid-sodium citrate buffer solution is prepared by mixing citric acid and sodium citrate in a mass ratio of (0.5-1.5):(2-4).

5. The chemical mechanical polishing slurry for soft magnetic alloys as described in claim 4, characterized in that: The citric acid-sodium citrate buffer solution is prepared by mixing citric acid and sodium citrate in a mass ratio of 1:

3.

6. The chemical mechanical polishing slurry for soft magnetic alloys as described in claim 1, characterized in that: During the preparation of the polishing fluid, the various raw material components are mixed and then subjected to ultrasonic vibration treatment and stirring to form a uniform and stable suspension.

7. A polishing method for polishing soft magnetic alloys, characterized in that: It includes the following steps: The soft magnetic alloy is ground to remove deep scratches from its surface; The soft magnetic alloy after grinding was subjected to chemical mechanical polishing (CMP) to reduce the surface roughness of the soft magnetic alloy to the submicron level. The CMP process is as follows: the polishing disc speed is 60 rpm to 90 rpm, the flow rate of the polishing fluid is 10 mL / min to 15 mL / min, the polishing pressure is 30 kPa to 40 kPa, and the polishing time is 40 min to 60 min. After polishing, the surface of the soft magnetic alloy is cleaned and dried. The soft magnetic alloy after rough polishing is subjected to chemical mechanical polishing (CMP) to obtain a soft magnetic alloy with a smooth and flat surface by using the polishing slurry described in any one of claims 1 to 6. The polishing process for fine polishing is as follows: the polishing disc rotation speed is 60 rpm to 80 rpm, the flow rate of the polishing slurry is 3 mL / min to 5 mL / min, the polishing pressure is 30 kPa to 40 kPa, and the polishing time is 40 min to 60 min. After polishing, the surface of the soft magnetic alloy is cleaned and dried.

8. The polishing method as described in claim 7, characterized in that: The coarse polishing slurry is prepared by mixing hydrogen peroxide, acidic silica sol, cerium oxide and deionized water.

9. The polishing method as described in claim 7, characterized in that: The grinding process uses 2000-4000 grit sandpaper, and the polishing pad used in the chemical mechanical polishing process is made of frosted leather.

10. The polishing method as described in claim 7, characterized in that: The surfaces of the soft magnetic alloys after polishing are cleaned sequentially with deionized water and anhydrous ethanol, and then dried with compressed air. The Sa value of the soft magnetic alloys after fine polishing is 0.104 nm to 0.123 nm.

Images