Grinding fluid for thinning ceramic substrate with high radius-thickness ratio and preparation method of grinding fluid

Abstract

The invention discloses grinding fluid for thinning a ceramic substrate with a high radius-thickness ratio and a preparation method of the grinding fluid, and belongs to the technical field of electronic ceramic substrate processing technologies. The grinding fluid comprises the following raw material components in percentage by mass: 5-25% of grinding particles A, 1-6% of grinding particles B, 0.01-20% of a dispersing lubricant, 0.01-10% of a metal corrosion inhibitor and the balance of a pH value regulator and water, wherein the hardness of the grinding particles A is lower than that of the grinding particles B. The preparation method of the grinding fluid comprises the following steps: performing plasma spheroidizing treatment on the grinding particles A to obtain spherical grinding particles, performing screening treatment on the grinding particles B to obtain rhombic grinding particles, proportioning according to a ratio, adding the grinding particles into water, performing ultrasonic dispersion, adding other raw materials, uniformly mixing, and adjusting the pH value to 8-10. The invention can effectively solve the problems of poor surface state, low processing efficiency and the like of the existing grinding fluid after grinding.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic ceramic substrate processing technology, and in particular relates to a grinding liquid for thinning a ceramic substrate with a high diameter-to-thickness ratio and a preparation method thereof. Background Art

[0002] Ceramic substrates are widely used in electronic information, new energy, aerospace and other fields. Grinding and polishing are essential processes for substrate processing, mainly used to remove attachments, improve flatness, and obtain thinner metallization layers. However, due to the high hardness and brittleness of ceramic substrates, cracks are easily generated during the processing process, surface processing is difficult, and it is difficult to ensure the quality and integrity of the surface and sub-surface after processing. This is inconsistent with the fact that ceramic surface processing not only requires high dimensional accuracy and shape accuracy, low surface roughness and good surface integrity, but also requires that the application of ceramic substrates also requires the substrate surface to be defect-free, damage-free and ultra-smooth. Therefore, achieving high-quality grinding and polishing processing on the surface of ceramic substrates is the key and difficulty of substrate material preparation technology.

[0003] During the substrate processing, grinding needs to ensure that the ceramic substrate does not break, and the dimensional accuracy, surface roughness, appearance, etc. meet the processing requirements. Therefore, the selection of grinding methods, equipment, and grinding fluids are all crucial. The thinner the ceramic substrate, the more difficult it is to control product quality. Ceramic substrates are basically thin sheets with a thickness of less than or equal to 0.381mm. This process increases the processing requirements. Under normal circumstances, the thinner the product, the lower the speed and pressure will be in the process, and the efficiency will be seriously reduced. Therefore, it is very important to develop grinding fluids that meet high-quality and efficient grinding and polishing processing.

[0004] Traditional grinding fluids used for thinning high-diameter-to-thickness ratio ceramic substrates mainly use free abrasives for processing. Abrasives with high hardness have high efficiency, but poor surface conditions, while abrasives with low hardness have good surface conditions but low efficiency. For example, grinding fluids with diamond as abrasive particles mainly remove materials from ceramic substrates through micro-scratching. Although efficient, it is very easy to cause serious scratches on the surface of ceramic substrates. At the same time, diamond is expensive, resulting in high processing costs. Secondly, grinding fluids with one of silicon carbide, aluminum oxide, and zirconium corundum as abrasive particles mainly remove materials from ceramic substrates through rolling and scraping. The products processed with this type of abrasive have good appearance and are uniform and scratch-free, but the disadvantages are low processing efficiency, short service life, and easy product damage. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the existing grinding liquid used for thinning high diameter-to-thickness ratio ceramic substrates cannot simultaneously meet the requirements of good surface condition of the abrasive product without scratches, high processing efficiency and low processing cost.

[0006] In view of the above shortcomings, the present invention proposes a grinding liquid containing composite particles, which buffers the rolling and scraping effects of the high-hardness abrasive on the product by adding low-hardness spherical abrasive particles to high-hardness prismatic abrasive particles, thereby achieving efficient, low-cost, high-consistency, high-yield, and long-life thinning processing of high-diameter-to-thickness ratio ceramic substrates.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] In a first aspect, the present invention provides a grinding liquid for thinning a high aspect ratio ceramic substrate: the raw material components of the grinding liquid are as follows by mass percentage: 5-25% grinding particles A, 1-6% grinding particles B, 0.01-20% dispersing lubricant, 0.01-10% metal corrosion inhibitor, and the remainder is pH regulator and water.

[0009] The abrasive particles A are one or more of cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, aluminum oxide, and silicon dioxide.

[0010] Furthermore, the abrasive particles A are spherical abrasive particles obtained by plasma spheroidization technology, and the sphericity thereof is greater than 95%.

[0011] The abrasive particles B are one or more of diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, and aluminum oxide, which have a higher hardness than the abrasive particles A.

[0012] Furthermore, the abrasive particles B are prismatic abrasive particles obtained by filtering and screening, and the number of edges and corners thereof is greater than 6.

[0013] The above-mentioned dispersing lubricant is one or more of sodium polyacrylate, polyvinyl alcohol, polyacrylamide, polyvinyl ether, polyvinyl ether acrylate, polyvinyl ether acrylic acid, and polyvinyl ether acrylate sulfonate.

[0014] The metal corrosion inhibitor is one or more of sodium nitrite, potassium dichromate, benzotriazole, thiazole, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium silicate.

[0015] The pH adjuster is one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, barium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

[0016] Furthermore, the pH adjuster is used in an amount to adjust the pH of the polishing liquid to be stable at 8-10.

[0017] In a second aspect, the present invention provides a method for preparing the above-mentioned grinding liquid for thinning a high aspect ratio ceramic substrate, comprising the following steps:

[0018] S1 prepares abrasive particles A and abrasive particles B, and then prepares materials according to the raw material components of the grinding liquid;

[0019] S2 adds spherical abrasive particles and prismatic abrasive particles into water, and disperses them uniformly by ultrasonic and mechanical stirring to obtain a composite abrasive solution;

[0020] S3 adds a dispersing lubricant to the composite abrasive solution and stirs until the mixture is uniform to obtain a first mixed solution;

[0021] S4 adds a metal corrosion inhibitor to the first mixed solution and stirs until the mixture is uniform to obtain a second mixed solution;

[0022] S5: adding a pH adjuster into the second mixed solution to adjust the pH of the system to be stable at 8-10, thereby obtaining a grinding liquid for thinning a high aspect ratio ceramic substrate.

[0023] Furthermore, in step S1, the preparation method of the abrasive particles A and the abrasive particles B is:

[0024] At least two selected from diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, aluminum oxide, and silicon dioxide as abrasives;

[0025] When only two types of abrasives are selected, the abrasive with lower hardness is used as abrasive particle A, and is processed by plasma spheroidization technology to obtain spherical abrasive particles with a sphericity of more than 95%; the abrasive with higher hardness is used as abrasive particle B, and is filtered and screened to obtain rhombus-shaped abrasive particles with more than 6 edges and corners;

[0026] When more than two types of abrasives are selected, the average hardness of the selected abrasives is calculated, and the abrasive with hardness less than the average hardness is used as abrasive particles A, and is processed by plasma spheroidization technology to obtain spherical abrasive particles with a sphericity greater than 95%; the abrasive with hardness ≥ the average hardness is used as abrasive particles B, and diamond-shaped abrasive particles with the number of edges and corners greater than 6 are obtained by filtering and screening.

[0027] Furthermore, in step S1, the preparation method of the abrasive particles A and the abrasive particles B is:

[0028] At least one abrasive selected from cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, aluminum oxide, and silicon dioxide as abrasive particles A, and processed by plasma spheroidization technology to obtain spherical abrasive particles with a sphericity greater than 95%;

[0029] At least one abrasive having a harderness higher than that of the selected abrasive particles A is selected from diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum and aluminum oxide as abrasive particles B, and diamond-shaped abrasive particles with more than 6 edges and corners are obtained by filtering and screening.

[0030] Furthermore, the content a of the above-mentioned abrasive particles A should be in the range of: πn / 6≤a≤πn / 5, where n is the rotation speed of the lower grinding disc of the machine.

[0031] Furthermore, the content b of the above-mentioned abrasive particles B should be in the range of πn / 30≤b≤πn / 20, where n is the rotation speed of the lower grinding disc of the machine.

[0032] The beneficial effects of the present invention are as follows: the present invention proposes a grinding liquid containing composite particles, which realizes the high-efficiency, low-cost, high-consistency, high-yield, and long-life thinning processing of high-diameter-to-thickness ratio ceramic substrates by regulating the rolling effect of relatively low-hardness spherical particles and the micro-scratching effect of relatively high-hardness prismatic particles. Compared with traditional grinding liquids, the grinding liquid for thinning high-diameter-to-thickness ratio ceramic substrates provided by the present invention has a cost that is more than 70% lower under the premise of the same high grinding efficiency; the yield rate is higher, and the ceramic substrate is less likely to be damaged; there are no scratches on the surface caused by processing, and the thickness consistency is good. The grinding liquid for thinning high-diameter-to-thickness ratio ceramic substrates of the present invention can be recycled and reused, and the utilization rate of the grinding liquid is high. DETAILED DESCRIPTION

[0033] The technical solution of the present invention can be specifically implemented in the following manner.

[0034] The present invention provides a grinding liquid for thinning a ceramic substrate with a high aspect ratio, which comprises the following components: 5-25wt% of relatively low hardness spherical particles, 1-6wt% of relatively high hardness prismatic particles, 0.01-20wt% of a dispersing lubricant, 0.01-10wt% of a metal corrosion inhibitor, a small amount of a pH value regulator, and the remaining components are water; wt% represents the mass percentage. The relatively high hardness refers to the higher hardness when the prismatic particles are compared with the spherical particles, and the relatively low hardness refers to the lower hardness when the spherical particles are compared with the prismatic particles.

[0035] The relatively low hardness spherical particles include one or more of cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, aluminum oxide, and silicon dioxide; the preparation of the spherical particles is achieved by plasma spheroidization technology.

[0036] The higher hardness prismatic particles include one or more of diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, and aluminum oxide, in addition to the lower hardness spherical particles, and the hardness is higher than that of the lower hardness spherical particles; the prismatic abrasive particles do not require special treatment, that is, they are obtained by filtering and screening conventional abrasives on the market.

[0037] The particle sizes of the spherical particles and the prismatic particles are both 20 μm, and the hardness of the abrasive particles is ranked from large to small as follows: diamond> cubic boron nitride> boron carbide> silicon carbide> silicon nitride> corundum> aluminum oxide> silicon dioxide.

[0038] A higher hardness means that the spherical particles are higher when compared with the prismatic particles, and a lower hardness means that the spherical particles are lower when compared with the prismatic particles.

[0039] The metal corrosion inhibitor comprises one or more of sodium nitrite, potassium dichromate, benzotriazole, thiazole, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium silicate;

[0040] The dispersing lubricant comprises one or more of sodium polyacrylate, polyvinyl alcohol, polyacrylamide, polyvinyl ether, polyvinyl ether acrylate, polyvinyl ether acrylic acid, and polyvinyl ether acrylate sulfonate;

[0041] The pH adjuster includes one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, barium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

[0042] The preparation method of the grinding liquid is:

[0043] 1. The two types of abrasive particles are selected according to the material characteristics of the ceramic substrate to be processed. The abrasive particles with lower hardness are processed by plasma spheroidization technology to obtain spherical particles (sphericity must be greater than 95%), and the abrasive particles with higher hardness are filtered to obtain prismatic particles (the number of edges and corners is greater than 6);

[0044] 2. The range of the content a of the lower hardness spherical particles should be: πn / 6≤a≤πn / 5 (n is the rotation speed of the lower plate of the machine grinding plate);

[0045] 3. The content b of prismatic particles with higher hardness should be within the range of πn / 30≤b≤πn / 20 (n is the rotation speed of the lower grinding disc of the machine);

[0046] 4. Add the lower hardness spherical particles and the higher hardness prismatic particles into water in proportion, and disperse them evenly by ultrasonic and mechanical stirring to obtain a composite abrasive solution;

[0047] 5. Add the dispersing lubricant to the composite abrasive solution and stir until the mixture is uniformly mixed to obtain a first mixed solution;

[0048] 6. Add metal corrosion inhibitor to the first mixed solution and stir until the mixture is uniformly mixed to obtain a second mixed solution;

[0049] 7. Add a pH adjuster to the second mixed solution and adjust the pH of the system to 8-10;

[0050] 8. Continue stirring and determine whether the pH value of the system is stable in the range of 8 to 10. If it is within the target range, the coarse grinding liquid product is obtained. If not, repeat steps 7 and 8.

[0051] In one embodiment of the present invention, the specific preparation method of the two abrasive particles is: selecting at least two from diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, aluminum oxide, and silicon dioxide as abrasives;

[0052] When only two types of abrasives are selected, the abrasive with lower hardness is used as spherical particles with lower hardness, and the plasma spheroidization technology is used to process the spherical abrasive particles with a sphericity greater than 95%; the abrasive with higher hardness is used as rhombic particles with higher hardness, and the rhombic abrasive particles with the number of edges and corners greater than 6 are obtained by filtering and screening;

[0053] When more than two types of abrasives are selected, the average hardness of the selected abrasives is calculated, and the abrasives with hardness less than the average hardness are taken as spherical particles with lower hardness, and are processed into spherical abrasive particles with sphericity greater than 95% by plasma spheroidization technology; the abrasives with hardness ≥ the average hardness are taken as rhombus particles with higher hardness, and rhombus abrasive particles with the number of edges and corners greater than 6 are obtained by filtering and screening.

[0054] In one embodiment of the present invention, the specific preparation method of the two types of abrasive particles is as follows: at least one abrasive is selected from cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, alumina, and silicon dioxide as spherical particles with lower hardness, and the particles are processed into spherical abrasive particles with a sphericity greater than 95% using plasma spheroidization technology; at least one abrasive with a hardness higher than the selected spherical particles with lower hardness is selected from diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, and alumina as rhombic particles with higher hardness, and rhombic abrasive particles with an edge number greater than 6 are obtained by filtering and screening.

[0055] The technical solution and effects of the present invention are further illustrated below through practical examples.

[0056] Example

[0057] 1. Preparation of grinding fluid

[0058] (1) The present invention provides three groups (Examples 1 to 3) of grinding liquids containing composite abrasive particles prepared according to the grinding liquid preparation method in the specific implementation manner, and the specific components thereof are shown in Table 1.

[0059] Table 1 Example grinding liquid components wt%

[0060]

[0061] (2) The present invention further provides four groups (Comparative Examples 1 to 4) of grinding liquids as the control group of Example 1, and their specific components are shown in Table 2.

[0062] Table 2 Comparative Example Grinding Liquid Components wt%

[0063]

[0064] In Table 1 and Table 2, the particle size of the spherical abrasive particles and the prismatic abrasive particles is 20 μm.

[0065] 2. Application of grinding fluid

[0066] The ceramic substrate was roughly ground using the grinding liquids prepared in the above embodiments and comparative examples. The grinding conditions of each embodiment and comparative example are as follows.

[0067] Example 1

[0068] Grinding machine: 18B double-sided iron disc machine; substrate to be ground: silicon nitride ceramic substrate; number of substrates to be ground: 16pcs; grinding liquid: cast iron disc (slotted); grinding pressure: 400kg; lower disc grinding speed: 30rpm; upper disc grinding speed: 18rpm; sun gear grinding speed: 23rpm; grinding time: 60min; grinding liquid flow rate: 250~300ml / min.

[0069] Example 2

[0070] Grinding machine: 13B double-sided iron disc machine; Grinded substrate: alumina ceramic substrate; Number of ground substrates: 120pcs; Grinding liquid: cast iron disc (slotted); Grinding pressure: 200kg; Lower disc grinding speed: 20rpm; Upper disc grinding speed: 15rpm; Sun gear grinding speed: 18rpm; Grinding time: 30min; Grinding liquid flow rate: 200~240ml / min.

[0071] Example 3

[0072] Grinding machine: 9B double-sided iron disc machine; substrate to be ground: beryllium oxide ceramic substrate; number of substrates to be ground: 20pcs; grinding liquid: cast iron disc (slotted); grinding pressure: 100kg; lower disc grinding speed: 25rpm; upper disc grinding speed: 225rpm; sun gear grinding speed: 23rpm; grinding time: 5min; grinding liquid flow rate: 150~200ml / min.

[0073] Comparative Example 1 The grinding conditions are the same as those in Example 1.

[0074] The grinding conditions of Comparative Example 2 are the same as those of Example 1.

[0075] The grinding conditions of Comparative Example 3 are the same as those of Example 1.

[0076] The grinding conditions of Comparative Example 4 are the same as those of Example 1.

[0077] The grinding performance of the grinding fluids in the above embodiments and comparative examples was tested, and the results are shown in Table 3.

[0078] Table 3 Grinding performance of grinding fluid

[0079]

[0080] It can be seen from the data in Table 3 that Comparative Example 1 uses a single spherical abrasive with a low hardness value, and although its surface scratches are few, the grinding efficiency is greatly reduced; Comparative Example 2 uses a single diamond abrasive with a high hardness value, and although the grinding efficiency is improved, it leads to more surface scratches and greater surface roughness; Although Comparative Examples 3 and 4 use abrasives of mixed hardness, the abrasive particles have the same morphology, and the comprehensive grinding performance cannot reach the effect of the embodiment of the present invention.

[0081] In summary, the grinding liquid for thinning high aspect ratio ceramic substrates of the present invention has better grinding performance than those of comparative examples 1 to 4, and can realize high efficiency, low cost, high consistency, high yield, and long service life thinning processing of high aspect ratio ceramic substrates, and has promotion and application value.

Claims

1. A grinding fluid for thinning a ceramic substrate with a high diameter-to-thickness ratio, characterized in that: The raw material components of the grinding liquid are as follows by mass percentage: 5-25% of grinding particles A, 1-6% of grinding particles B, 0.01-20% of dispersing lubricant, 0.01-10% of metal corrosion inhibitor, and the balance is pH regulator and water; The abrasive particles A are one or more of cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, aluminum oxide, and silicon dioxide; The abrasive particles B are one or more of diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, and aluminum oxide, which have a higher hardness than the abrasive particles A; The pH value adjusting agent is used in an amount to adjust the pH value of the grinding liquid to be stable at 8-10.

2. The grinding liquid for thinning a high aspect ratio ceramic substrate according to claim 1, characterized in that: The abrasive particles A are spherical abrasive particles obtained by plasma spheroidization technology, and the sphericity thereof is greater than 95%.

3. The grinding liquid for thinning a high aspect ratio ceramic substrate according to claim 1, characterized in that: The abrasive particles B are prismatic abrasive particles obtained by filtering and screening, and the number of edges and corners thereof is greater than 6.

4. The grinding liquid for thinning a high aspect ratio ceramic substrate according to claim 1, characterized in that: The dispersing lubricant is one or more of sodium polyacrylate, polyvinyl alcohol, polyacrylamide, polyvinyl ether, polyvinyl ether acrylate, polyvinyl ether acrylic acid, and polyvinyl ether acrylate sulfonate.

5. The grinding liquid for thinning a high aspect ratio ceramic substrate according to claim 1, characterized in that: The metal corrosion inhibitor is one or more of sodium nitrite, potassium dichromate, benzotriazole, thiazole, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium silicate.

6. The grinding liquid for thinning a high aspect ratio ceramic substrate according to claim 1, characterized in that: The pH regulator is one or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, barium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

7. The method for preparing a grinding liquid for thinning a high aspect ratio ceramic substrate according to any one of claims 1 to 6, characterized in that: The steps include: S1 prepares abrasive particles A and abrasive particles B, and then prepares materials according to the raw material components of the grinding liquid; S2 adds spherical abrasive particles and prismatic abrasive particles into water, and disperses them uniformly by ultrasonic and mechanical stirring to obtain a composite abrasive solution; S3 adds a dispersing lubricant to the composite abrasive solution and stirs until the mixture is uniform to obtain a first mixed solution; S4 adds a metal corrosion inhibitor to the first mixed solution and stirs until the mixture is uniform to obtain a second mixed solution; S5: adding a pH adjuster into the second mixed solution to adjust the pH of the system to be stable at 8-10, thereby obtaining a grinding liquid for thinning a high aspect ratio ceramic substrate.

8. The method for preparing a grinding liquid for thinning a high aspect ratio ceramic substrate according to claim 7, characterized in that: In step S1, the preparation method of abrasive particles A and abrasive particles B is: selecting at least two from diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, aluminum oxide, and silicon dioxide as abrasives; When only two types of abrasives are selected, the abrasive with lower hardness is used as abrasive particle A, and is processed by plasma spheroidization technology to obtain spherical abrasive particles with a sphericity of more than 95%; the abrasive with higher hardness is used as abrasive particle B, and is filtered and screened to obtain rhombus-shaped abrasive particles with more than 6 edges and corners; When more than two types of abrasives are selected, the average hardness of the selected abrasives is calculated, and the abrasives with hardness less than the average hardness are used as abrasive particles A, which are processed by plasma spheroidization technology to spherical abrasive particles with a sphericity greater than 95%; Abrasives with a hardness ≥ average hardness are used as abrasive particles B, and diamond-shaped abrasive particles with a corner number of >6 are obtained by filtering and screening.

9. The method for preparing a grinding liquid for thinning a high aspect ratio ceramic substrate according to claim 7, characterized in that: In step S1, the preparation method of abrasive particles A and abrasive particles B is as follows: at least one abrasive is selected from cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, aluminum oxide, and silicon dioxide as abrasive particles A, and the abrasive particles are processed into spherical abrasive particles with a sphericity greater than 95% by plasma spheroidization technology; at least one abrasive having a hardness higher than that of the selected abrasive particles A is selected from diamond, cubic boron nitride, boron carbide, silicon carbide, silicon nitride, corundum, and aluminum oxide as abrasive particles B, and diamond-shaped abrasive particles with an edge number greater than 6 are obtained by filtering and screening.

10. The method for preparing a grinding liquid for thinning a ceramic substrate with a high aspect ratio according to claim 8 or 9, characterized in that: The content a of the abrasive particles A should be in the range of πn / 6≤a≤πn / 5, and the content b of the abrasive particles B should be in the range of πn / 30≤b≤πn / 20; wherein n is the rotation speed of the lower grinding disc of the machine.

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