An electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing

Abstract

This invention discloses an electroplating process for ultra-fine diamond cutting blades used in ultra-thin wafer dicing, relating to the field of blade electroplating technology. The process includes the following steps: Step 1, adding diamond particles with a diameter of 1-5 micrometers to a nickel sulfamate electroplating solution; Step 2, using a stainless steel or cemented carbide blade ring substrate as the cathode, sequentially performing degreasing, alkaline washing, acid washing, and activation treatments. The cavitation effect can be used to break up agglomerates of diamond particles, allowing the particles to be uniformly suspended in the electroplating solution, thus solving the problem of easy agglomeration of ultra-fine particles. Through a pre-plated transition anchoring layer, a uniform and dense nickel layer can be formed on the substrate surface, providing anchoring sites for subsequent diamond particle embedding. Simultaneously, the interface composition of the pre-plated layer and the co-deposited layer is consistent, improving the adhesion between the plating layer and the substrate.

Description

Technical Field

[0001] This invention belongs to the field of blade electroplating technology, specifically an electroplating preparation process for ultra-fine-grained diamond blades used for ultra-thin wafer cutting. Background Technology

[0002] With the development of semiconductor technology, the thickness of wafers is constantly decreasing, and the precision cutting of ultra-thin wafers places higher demands on the accuracy and lifespan of cutting blades. Electroplating is a commonly used method for preparing diamond cutting blades, which involves co-depositing diamond particles with nickel metal on a substrate to form the cutting edge.

[0003] In existing technologies, the preparation of electroplated diamond cutting tools typically suffers from the following problems: First, for ultrafine diamond particles, due to their large specific surface area and high surface energy, they are prone to agglomeration in the electroplating solution, resulting in uneven particle distribution in the coating and affecting the cutting performance of the tool; Second, improper control of substrate pretreatment and preplating processes leads to insufficient adhesion between the substrate and the coating, making the coating prone to peeling off during tool use; Third, insufficient precision in controlling the exposure rate of diamond particles can easily result in particles being embedded too deeply, leading to insufficient cutting ability, or embedded too shallowly, leading to particle detachment; Fourth, residual stress exists in the electroplated coating, which can easily cause tool deformation and affect cutting accuracy.

[0004] These problems make it difficult for existing blades to meet the cutting requirements of ultra-thin wafers. The cutting grooves are wide, the edge chipping is obvious, the surface roughness is high, and the blade life is short. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention urgently requires an electroplating process for diamond cutting tools that can overcome these defects.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] Specifically, an electroplating process for preparing ultra-fine-grained diamond cutting blades for ultra-thin wafer dicing is proposed, including the following steps:

[0008] Step 1: Add diamond particles with a particle size of 1-5 micrometers to the nickel aminosulfonate electroplating solution and disperse them ultrasonically at a frequency of 20-40kHz to break up the agglomerated diamond particles and suspend them uniformly in the electroplating solution.

[0009] Step 2: Using the stainless steel or cemented carbide blade ring substrate as the cathode, perform degreasing, alkaline washing, acid washing and activation treatment in sequence.

[0010] Step 3: The substrate treated in Step 2 is placed in a nickel sulfamate electroplating solution that does not contain diamond particles. The nickel sulfamate electroplating solution that does not contain diamond particles has the same composition as the nickel sulfamate electroplating solution in Step 1. High-purity nickel is used as the anode, and a nickel undercoating layer with a thickness of 1-2 micrometers is pre-plated under a current density of 0.5-1.0 A / dm^2. The nickel undercoating layer serves as a transition anchoring layer.

[0011] Step four: The substrate pre-plated in step three is transferred into the electroplating solution containing diamond particles obtained in step one. High-purity nickel is used as the anode. Under the conditions of current density of 1.5-2.5 A / dm^2, temperature of 50-55 degrees Celsius, and pH value of 3.50-4.50, mechanical stirring and ultrasonic dispersion are applied simultaneously to perform diamond co-deposition electroplating. The current density is higher than the current density of the pre-plating in step three. The exposure rate of diamond on the coating surface is controlled by adjusting the current density and mechanical stirring intensity, so that diamond particles and nickel coating are co-deposited on the substrate surface to form a cutting edge.

[0012] Step 5: Perform stress-relief annealing on the workpiece after electroplating in Step 4 at a temperature of 150-200 degrees Celsius for 0.5-2 hours. Step 6: Perform mechanical or electrolytic sharpening on the workpiece after annealing in Step 5.

[0013] Furthermore, in step one, the single crystal ratio of the diamond particles is greater than or equal to 90%, and the impurity content is less than or equal to 25 ppm. Before being added to the nickel aminosulfonate electroplating solution, the diamond particles are subjected to acid washing and purification treatment. The acid washing and purification treatment uses a 30%-50% volume fraction of dilute hydrochloric acid or dilute nitric acid solution to soak the diamond particles at room temperature for 2-4 hours. After treatment, the particles are washed with deionized water until neutral and dried at 80-100 degrees Celsius to constant weight.

[0014] Furthermore, in step one, the diamond particles have a particle size of 2-3 micrometers, the single crystal ratio of the diamond particles is greater than or equal to 92%, the impurity content is less than or equal to 20 ppm, and the ultrasonic dispersion frequency is 25-35 kHz.

[0015] Furthermore, in step two, an ultrasonic cleaning step is added after alkaline washing and before acid washing. The ultrasonic cleaning uses deionized water, the ultrasonic frequency is 30-50kHz, and the cleaning time is 2-5min. After activation, a passivation treatment step is added. The passivation treatment uses a chromic acid solution with a concentration of 1-3g / L for 5-10s.

[0016] Furthermore, the pre-plating in step three is carried out under the condition of a current density of 0.6-0.8 A / dm^2, the pre-plating time is 3-8 min, and the thickness of the nickel undercoat is 1.2-1.8 micrometers.

[0017] Furthermore, in step three, a polyester filter bag is provided outside the high-purity nickel anode. The polyester filter bag is used to trap the anode mud generated by anode dissolution, and the filtration accuracy of the polyester filter bag is 10-25 micrometers.

[0018] Furthermore, the current density of the co-deposition electroplating in step four is 1.8-2.2 A / dm^2, and the difference between the current density of the co-deposition electroplating and the current density of the pre-plating in step three (0.6-0.8 A / dm^2) is 1.0-1.6 A / dm^2.

[0019] Furthermore, in the nickel sulfamate electroplating solution described in step one and the nickel sulfamate electroplating solution without diamond particles described in step three, the concentration of nickel sulfamate is 300-450 g / L, the concentration of nickel chloride is 20 g / L, the concentration of boric acid is 30-40 g / L, the concentration of surfactant is 0.05-0.2 g / L, the solvent is deionized water, and the pH value of the electroplating solution is adjusted to 3.50-4.50 using dilute hydrochloric acid or dilute ammonia.

[0020] Furthermore, the surfactant is selected from sodium dodecyl sulfate, polyethylene glycol octylphenyl ether, or hexadecyltrimethylammonium bromide, and the concentration of the surfactant in the electroplating solution is 0.08-0.15 g / L.

[0021] Furthermore, in step four, the diamond exposure rate on the coating surface is increased by reducing the current density to 1.5-1.8 A / dm^2 and weakening the mechanical stirring intensity to 100-150 rpm, and the diamond exposure rate on the coating surface is reduced by increasing the current density to 2.2-2.5 A / dm^2 and strengthening the mechanical stirring intensity to 200-300 rpm, wherein the exposure rate is 20%-30%.

[0022] The technical solutions provided by the embodiments of this disclosure have at least the following beneficial effects:

[0023] Cavitation effect can be used to break up agglomerates of diamond particles, so that the particles are uniformly suspended in the electroplating solution, which solves the problem of easy agglomeration of ultrafine particles. Through pre-plating transition anchoring layer, a uniform and dense nickel layer can be formed on the substrate surface, providing anchoring sites for subsequent diamond particle embedding. At the same time, it ensures that the interface composition of the pre-plating layer and the co-deposited layer is consistent, which improves the bonding force between the plating layer and the substrate.

[0024] By synergistically controlling the current density and mechanical stirring intensity, the exposure rate of diamond particles can be precisely controlled, taking into account both the fixation strength of the particles and the cutting edge length. This avoids problems caused by excessively high or low exposure rates. Through stress-relief annealing, the residual internal stress of the coating can be reduced, lattice defects can be minimized, and the deformation of the cutting tool can be prevented, thereby improving the dimensional stability of the cutting tool. Attached Figure Description

[0025] Figure 1 This is a system flowchart of the present invention;

[0026] Figure 2 This is a performance comparison chart of the present invention. Detailed Implementation

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

[0028] Please see Figure 1 This application provides an electroplating preparation process for ultra-fine diamond cutting blades for ultra-thin wafer cutting, including the following steps: Step 1, diamond particles with a particle size of 1-5 micrometers are added to nickel aminosulfonate electroplating solution and ultrasonically dispersed at a frequency of 20-40kHz to break up the agglomerated diamond particles and suspend them uniformly in the electroplating solution.

[0029] Step 2: Using the stainless steel or cemented carbide blade ring substrate as the cathode, perform degreasing, alkaline washing, acid washing and activation treatment in sequence.

[0030] Step 3: The substrate treated in Step 2 is placed in a nickel sulfamate electroplating solution that does not contain diamond particles. The nickel sulfamate electroplating solution that does not contain diamond particles has the same composition as the nickel sulfamate electroplating solution in Step 1. High-purity nickel is used as the anode, and a nickel undercoating layer with a thickness of 1-2 micrometers is pre-plated under a current density of 0.5-1.0 A / dm^2. The nickel undercoating layer serves as a transition anchoring layer.

[0031] Step four: The substrate pre-plated in step three is transferred into the electroplating solution containing diamond particles obtained in step one. High-purity nickel is used as the anode. Under the conditions of current density of 1.5-2.5 A / dm^2, temperature of 50-55 degrees Celsius, and pH value of 3.50-4.50, mechanical stirring and ultrasonic dispersion are applied simultaneously to perform diamond co-deposition electroplating. The current density is higher than the current density of the pre-plating in step three. The exposure rate of diamond on the coating surface is controlled by adjusting the current density and mechanical stirring intensity, so that diamond particles and nickel coating are co-deposited on the substrate surface to form a cutting edge.

[0032] Step 5: Perform stress-relief annealing on the workpiece after electroplating in Step 4 at a temperature of 150-200 degrees Celsius for 0.5-2 hours. Step 6: Perform mechanical or electrolytic sharpening on the workpiece after annealing in Step 5.

[0033] In step one, the diamond particles have a diameter of 1-5 micrometers. The specific surface area of ​​spherical particles is calculated using the formula S=6 / (rho*d), where rho is the particle density and d is the particle diameter. The density of diamond is 3.52 g / cm^3. Taking a diamond particle with a diameter of 2 micrometers as an example, its specific surface area is S=6 / (3.52*2*10^-4cm)=8.52*10^5cm^2 / g;

[0034] Based on diamond particles with a diameter of 40 micrometers, its specific surface area S = 6 / (3.52*40*10^-4cm) = 4.26*10^4cm^2 / g.

[0035] The specific surface area of ​​2-micrometer particles is 20 times that of 40-micrometer particles. This increased specific surface area significantly raises the surface energy of the particles in the electroplating solution, causing them to aggregate through van der Waals forces. The ultrasonic dispersion utilizes the cavitation effect generated by ultrasound in the electroplating solution. The localized high-temperature, high-pressure shock waves released when the cavitation bubbles burst act on the aggregates, causing them to break up and disperse.

[0036] In step two, the degreasing process involves treating the substrate surface with an alkaline degreasing solution at 50-70 degrees Celsius for 5-10 minutes; the alkaline washing process involves treating the substrate surface with an alkaline solution of sodium hydroxide concentration of 30-50 g / L at 50-70 degrees Celsius for 5-10 minutes; the acid washing process involves treating the substrate surface with a dilute hydrochloric acid or dilute sulfuric acid solution with a volume fraction of 5%-10% for 1-3 minutes; and the activation process involves treating the substrate surface with a dilute sulfuric acid solution with a volume fraction of 10%-20% for 10-30 seconds. After each step, the substrate surface is rinsed with deionized water.

[0037] In step three, the transition anchoring layer refers to a nickel undercoat layer pre-plated on the substrate surface. This nickel undercoat layer forms a uniform and dense nickel metal layer on the substrate surface, providing anchoring sites for the embedding of diamond particles in the subsequent step four. The pre-plating is performed in an electroplating solution that does not contain diamond particles. The composition of the plating solution is the same as that of the nickel sulfamate electroplating solution described in step one, ensuring that the interface composition between the pre-plated layer and the co-deposited layer is consistent. The pre-plating current density is 0.5–1.0 A / dm², and the pre-plating time is 3–8 min.

[0038] The coating thickness is calculated according to Faraday's law of electrolysis: h = M * j * t * eta / (n * F * rho), where h is the coating thickness, M is the molar mass of nickel (58.69 g / mol), j is the current density, t is the time, eta is the current efficiency (0.95), n is the nickel ion valence (2), F is the Faraday constant (96485 C / mol), and rho is the nickel density (8.90 g / cm³). Using j = 0.8 A / dm² = 0.008 A / cm², and t = 6 min = 360 s, the calculation is as follows:

[0039] h = 58.69 * 0.008 * 360 * 0.95 / (2 * 96485 * 8.90) = 160.57 / 1717433 cm = 9.35 * 10^-5 cm = 0.935 micrometers.

[0040] Calculate using j = 0.8 A / dm^2 and t = 8 min = 480 s:

[0041] h = 58.69 * 0.008 * 480 * 0.95 / 1717433 = 214.26 / 1717433 cm = 1.247 micrometers. Using j = 1.0 A / dm² = 0.010 A / cm², and t = 8 min = 480 s, calculate:

[0042] h = 58.69 * 0.010 * 480 * 0.95 / 1717433 = 267.83 / 1717433 cm = 1.559 micrometers.

[0043] The measured coating thickness was verified using a scanning electron microscope cross-sectional observation method.

[0044] In step four, the exposure rate is defined as the ratio of the area of ​​the diamond particle exposed above the coating surface to the total cross-sectional area of ​​the particle. The exposure rate is controlled by two parameters: current density and mechanical stirring intensity.

[0045] Under conditions of current density of 1.5-2.5 A / dm², temperature of 50-55°C, and pH of 3.50-4.50, nickel ions are reduced and deposited on the cathode surface at a deposition rate v = k * j, where k is the electrochemical rate constant and j is the current density. Using j = 2.0 A / dm², the nickel deposition rate is approximately 1.0 μm / min. Mechanical stirring causes the diamond particles to move in the plating bath, and the collision frequency between the particles and the cathode surface is proportional to the stirring intensity. When the current density increases and the stirring intensity intensifies, the nickel deposition rate accelerates and particle movement intensifies, resulting in rapid embedding of the particles in the coating and a decrease in exposure rate. Conversely, when the current density decreases and the stirring intensity weakens, the nickel deposition rate slows down and particle movement decelerates, making it less likely for the tops of the particles to be covered by the coating, thus increasing the exposure rate.

[0046] In step five, the stress-relief annealing is performed at 150-200 degrees Celsius for 0.5-2 hours. During the annealing process, the lattice defects in the nickel plating recover, the grain size grows from 10-20 nm in the electroplated state to 30-50 nm, the lattice distortion energy decreases, and the residual internal stress decreases. The workpiece is then cooled to room temperature after annealing.

[0047] In step six, the mechanical sharpening uses diamond polishing paste to grind the cutting edge; the electrolytic sharpening uses the blade as the anode and a stainless steel plate as the cathode, and performs anodic dissolution sharpening by passing a direct current through a dilute acid electrolyte.

[0048] As an optional embodiment, the diamond particles in step one have a single crystal ratio greater than or equal to 90% and an impurity content less than or equal to 25 ppm. The diamond particles are acid-washed and purified before being added to the nickel sulfamate electroplating solution. The acid-washing and purification treatment uses a 30%-50% volume fraction of dilute hydrochloric acid or dilute nitric acid solution to soak the diamond particles at room temperature for 2-4 hours. After treatment, the particles are washed with deionized water until neutral and dried at 80-100 degrees Celsius to constant weight.

[0049] The single-crystal ratio refers to the percentage of single-crystal diamond in the total mass of the diamond particle. Single-crystal diamond has a complete sp^3 hybrid lattice structure and a microhardness of 10000-10200 HV; polycrystalline diamond contains grain boundaries, where sp^2 hybrid carbon phases exist, and the microhardness decreases to 8000-9000 HV. When the single-crystal ratio is greater than or equal to 90%, the hardness uniformity of the particle meets the cutting requirements.

[0050] The impurity content refers to the total content of elements other than carbon in the diamond particles, including metallic impurities and non-diamond carbon phase, determined by inductively coupled plasma mass spectrometry. When the impurity content is less than or equal to 25 ppm, the scratch density produced by the impurity particles on the wafer dicing surface is less than 0.5 scratches / mm².

[0051] The acid leaching and purification process involves immersing the diamond particles in a 30%–50% (v / v) dilute hydrochloric acid or dilute nitric acid solution at room temperature for 2–4 hours. The dilute acid dissolves the metal oxides and inorganic salt impurities on the particle surface, while the non-diamond carbon phase is oxidized and removed under acidic conditions. After treatment, the particles are washed with deionized water until neutral and dried at 80–100 degrees Celsius to constant weight. After acid leaching and purification, the impurity content of the diamond particles is measured to be in the range of 15–20 ppm.

[0052] As an optional embodiment, the diamond particles in step one have a particle size of 2-3 micrometers, the single crystal ratio of the diamond particles is greater than or equal to 92%, the impurity content is less than or equal to 20 ppm, and the ultrasonic dispersion frequency is 25-35 kHz.

[0053] The diamond particles have a particle size of 2-3 micrometers, which is a preferred range within the 1-5 micrometer range. Taking a particle with a particle size of 2.5 micrometers as an example, its specific surface area S = 6 / (3.52*2.5*10^-4cm) = 6.82*10^5cm^2 / g. When the ratio of the embedding depth of the 2-3 micrometer diamond particles in the nickel plating layer to the particle diameter is 0.4-0.5, the fixation strength of the particles and the cutting edge length are balanced. The single crystal ratio is greater than or equal to 92%, which is a preferred indicator of a single crystal ratio greater than or equal to 90%, and the impurity content is less than or equal to 20ppm, which is a preferred indicator of an impurity content less than or equal to 25ppm.

[0054] As an optional embodiment, an ultrasonic cleaning step is added after the alkaline washing and before the acid washing in step two. The ultrasonic cleaning uses deionized water, the ultrasonic frequency is 30-50kHz, and the cleaning time is 2-5min. After activation, a passivation treatment step is added. The passivation treatment uses a chromic acid solution with a concentration of 1-3g / L for 5-10s.

[0055] The ultrasonic cleaning step is performed after alkaline cleaning and before acid cleaning. Its function is to remove residual sodium hydroxide solution and microparticles from the micro-recesses on the substrate surface after alkaline cleaning. The cavitation effect generated by the ultrasonic frequency of 30-50kHz can effectively peel off the residues attached to the substrate surface. The passivation treatment step is performed after activation. Its function is to form an extremely thin chromium oxide passivation film on the substrate surface to prevent oxidation of the substrate during transfer to the electroplating tank. The concentration of the chromic acid solution is 1-3 g / L, the treatment time is 5-10 s, and the thickness of the formed passivation film is 2-5 nm. This passivation film is removed by reduction with cathodic current at the beginning of electroplating, and the reduction time is less than 10 s.

[0056] As an optional embodiment, the pre-plating in step three is carried out under the condition of a current density of 0.6-0.8A / dm^2, the pre-plating time is 3-8 min, and the thickness of the nickel undercoat is 1.2-1.8 micrometers.

[0057] The pre-plating current density of 0.6–0.8 A / dm² is a preferred range within the 0.5–1.0 A / dm² range, and the pre-plating time of 3–8 min corresponds to this current density range. The plating thickness is calculated according to Faraday's law of electrolysis: h = M * j * t * eta / (n * F * rho), where M = 58.69 g / mol, eta = 0.95, n = 2, F = 96485 C / mol, and rho = 8.90 g / cm³.

[0058] Calculate using j = 0.8 A / dm² = 0.008 A / cm²:

[0059] When t = 6 min = 360 s, h = 58.69 * 0.008 * 360 * 0.95 / 1717433 cm = 0.935 micrometers; when t = 8 min = 480 s, h = 58.69 * 0.008 * 480 * 0.95 / 1717433 cm = 1.247 micrometers. Calculated using j = 1.0 A / dm^2 = 0.010 A / cm^2:

[0060] When t=6min=360s, h=58.69*0.010*360*0.95 / 1717433cm=1.169 micrometers; when t=8min=480s, h=58.69*0.010*480*0.95 / 1717433cm=1.559 micrometers. Based on the above calculations, under the conditions of j=0.6-1.0A / dm^2 and t=3-8min, the calculated coating thickness is 0.47-1.56 micrometers. The measured values, obtained using scanning electron microscopy cross-sectional observation, are within the range of 1.2-1.8 micrometers.

[0061] As an optional embodiment, a polyester filter bag is provided outside the high-purity nickel anode in step three. The polyester filter bag is used to trap the anode mud generated by anode dissolution, and the filtration accuracy of the polyester filter bag is 10-25 micrometers.

[0062] The anode sludge is the detached material of tiny nickel particles generated during the oxidation and dissolution process of high-purity nickel anodes due to uneven local current density on the anode surface. The particle size distribution of the anode sludge is 5-50 micrometers, and the density is 8.90 g / cm^3. The polyester filter bag is a filter bag woven from polyester fibers with a pore size of 10-25 micrometers, which can effectively trap anode sludge particles larger than 10 micrometers. The water permeability of the polyester filter bag is greater than 500 L / (m^2*h), and the nickel ion permeability is greater than 99%. The replacement cycle of the polyester filter bag is determined according to the cumulative electroplating time. After 20-40 hours of electroplating, when the accumulated anode sludge reaches 60%-80% of the filter bag's retention capacity, it should be replaced.

[0063] As an optional embodiment, the current density of the co-deposition electroplating in step four is 1.8-2.2 A / dm^2, and the difference between the current density of the co-deposition electroplating and the current density of the pre-plating in step three (0.6-0.8 A / dm^2) is 1.0-1.6 A / dm^2.

[0064] The current density of the co-deposition electroplating is 1.8-2.2 A / dm^2, which is a preferred range within the range of 1.5-2.5 A / dm^2.

[0065] The current density difference Delta_j = j4 - j3, where j4 is the co-deposition current density in step four and j3 is the pre-plating current density in step three. Delta_j = 1.0 - 1.6 A / dm^2. The relationship between the nickel deposition rate v and the current density j is v = k * j, where k is the electrochemical rate constant. Calculated with k = 0.5 μm * dm^2 / (A * min), the pre-plating stage v3 = 0.5 * 0.7 = 0.35 μm / min, and the co-deposition stage v4 = 0.5 * 2.0 = 1.0 μm / min. The nickel deposition rate in the co-deposition stage is 2.86 times that in the pre-plating stage. This rate difference allows the diamond particles to be rapidly embedded and fixed after reaching the cathode surface.

[0066] As an optional embodiment, in the nickel sulfamate electroplating solution described in step one and the nickel sulfamate electroplating solution without diamond particles described in step three, the concentration of nickel sulfamate is 300-450 g / L, the concentration of nickel chloride is 20 g / L, the concentration of boric acid is 30-40 g / L, the concentration of surfactant is 0.05-0.2 g / L, the solvent is deionized water, and the pH value of the electroplating solution is adjusted to 3.50-4.50 using dilute hydrochloric acid or dilute ammonia.

[0067] The nickel sulfamate electroplating solution is a weakly acidic electroplating system with nickel sulfamate (Ni(NH2SO3)2)2 as the main salt. A nickel ion concentration of 300-450 g / L corresponds to a nickel ion concentration of 51-77 g / L, and the conductivity of the plating solution within this concentration range is 0.15-0.25 S / cm. A nickel chloride concentration of 20 g / L corresponds to a chloride ion concentration of 10.8 g / L. Chloride ions are adsorbed on the anode surface, promoting the active dissolution of the nickel anode and maintaining a stable nickel ion concentration in the plating solution. A boric acid concentration of 30-40 g / L forms a borate buffer system in the plating solution (H3BO3), stabilizing the pH value within the range of 3.50-4.50. The surfactant is an organic compound added to the electroplating solution to reduce interfacial tension, forming an adsorption layer on the surface of the diamond particles with a thickness of 2-5 nm.

[0068] As an optional embodiment, the surfactant is selected from sodium dodecyl sulfate, polyethylene glycol octylphenyl ether, or hexadecyltrimethylammonium bromide, and the concentration of the surfactant in the electroplating solution is 0.08-0.15 g / L.

[0069] The sodium dodecyl sulfate (C12H25OSO3Na) is an anionic surfactant with a critical micelle concentration (CMC) of 8.2 mmol / L = 2.36 g / L.

[0070] The polyethylene glycol octylphenyl ether (C34H62O11) is a nonionic surfactant with a CMC of 0.2-0.9 mmol / L = 0.13-0.58 g / L.

[0071] The hexadecyltrimethylammonium bromide (C16H33N(CH3)3Br) is a cationic surfactant with a CMC of 0.92 mmol / L = 0.34 g / L.

[0072] The surfactant concentration of 0.05–0.2 g / L is lower than the CMC values ​​of the three surfactants mentioned above. The surfactant exists in the plating solution in monomolecular form, forming a monomolecular adsorption layer on the surface of the diamond particles without micellization. A concentration of 0.08–0.15 g / L is the preferred range within the 0.05–0.2 g / L range. Within this concentration range, the absolute value of the Zeta potential of the diamond particles is greater than 30 mV, and the electrostatic repulsion between particles is sufficient to overcome van der Waals forces, resulting in good dispersion stability.

[0073] As an optional embodiment, in step four, the diamond exposure rate on the coating surface is increased by reducing the current density to 1.5-1.8 A / dm² and weakening the mechanical stirring intensity to 100-150 rpm, and the diamond exposure rate on the coating surface is reduced by increasing the current density to 2.2-2.5 A / dm² and strengthening the mechanical stirring intensity to 200-300 rpm, wherein the exposure rate is 20%-30%.

[0074] The exposure rate eta is defined as the ratio of the area of ​​the crown at the top of the diamond particle to the cross-sectional area of ​​the particle's equator. Calculated using a spherical particle model, the exposure rate eta = (h / d)^2, where h is the height of the particle's top exposed above the coating, and d is the particle diameter. An exposure rate of 20%-30% corresponds to h / d = 0.45-0.55, meaning that 45%-55% of the particle's top height is exposed above the coating surface, and the particle's embedding depth is 45%-55%d. When the exposure rate is below 20%, h / d < 0.45, indicating that the particle is embedded too deeply, resulting in insufficient effective cutting edge; when the exposure rate is above 30%, h / d > 0.55, indicating that the particle is embedded too shallowly, resulting in insufficient fixing strength.

[0075] The exposure rate is adjusted through the coordinated control of current density and mechanical stirring intensity. A mechanical stirring speed of 100-300 rpm corresponds to a stirring linear velocity of 0.5-1.5 m / s, and the relationship between the particle velocity vp in the plating solution and the stirring linear velocity vh is vp = 0.3-0.5vh. The collision frequency between the particles and the cathode surface is f = vp / delta, where delta is the diffusion layer thickness, delta = 0.05-0.1 mm.

[0076] Calculated with vh=1.0m / s and delta=0.07mm;

[0077] f = 0.4 * 1.0 / 0.00007 = 5714 s^-1, meaning the particles collide with the cathode surface approximately 5700 times per second. As the current density increases, the nickel deposition rate accelerates, and the particles are rapidly embedded after reaching the cathode, reducing the exposure rate. Increased stirring intensity leads to higher particle collision frequency and greater kinetic energy, causing the particles to embed deeper into the coating, further reducing the exposure rate.

[0078] The diamond cutting tool prepared using this invention has a thickness of 30-50 micrometers, a cutting groove width of 53-86 micrometers, a surface roughness Ra<=0.1 micrometers, and a maximum chipping width of less than or equal to 25 micrometers. It is suitable for precision cutting of ultra-thin wafers with a thickness of less than or equal to 100 micrometers.

[0079] The following is an illustration through specific examples:

[0080] Example 1: The electroplating preparation process of ultra-fine diamond cutting blades for ultra-thin wafer dicing in this example includes the following steps: Step 1: Take diamond particles with a particle size of 1-5 μm, add them to dilute hydrochloric acid with a volume fraction of 30%, soak them at room temperature for 2 hours to remove impurities on the particle surface, then wash them with deionized water until neutral, and dry them at 80°C to constant weight; add the treated diamond particles to nickel sulfamate electroplating solution, and ultrasonically disperse them at a frequency of 20 kHz for 30 minutes to break up the agglomerated diamond particles and suspend them uniformly in the electroplating solution; wherein the composition of the nickel sulfamate electroplating solution is: nickel sulfamate 300 g / L, nickel chloride 20 g / L, boric acid 30 g / L, sodium dodecyl sulfate 0.05 g / L, the solvent is deionized water, and the pH value is adjusted to 3.5. Step Two: Using the stainless steel blade ring substrate as the cathode, the following pretreatments were performed sequentially: alkaline degreasing (treatment with alkaline degreasing solution at 50℃ for 10 min); alkaline washing (treatment with 30 g / L sodium hydroxide solution at 50℃ for 10 min); ultrasonic cleaning (ultrasonic treatment with deionized water at 30 kHz for 2 min); acid washing (treatment with 5% (v / v) dilute hydrochloric acid for 3 min); activation (treatment with 10% (v / v) dilute sulfuric acid for 30 s); the substrate surface was rinsed with deionized water after each step. Step Three: The treated substrate was placed in a nickel sulfamate electroplating solution of the same composition without diamond particles. Using high-purity nickel as the anode, pre-plating was performed at a current density of 0.5 amperes per square decimeter for 8 min to obtain a 1.2 μm thick nickel undercoat layer, serving as a transition anchoring layer. Step 4: Transfer the pre-plated substrate into the electroplating solution containing diamond particles obtained in Step 1. Using high-purity nickel as the anode, and under conditions of a current density of 1.5 amperes per square decimeter, a temperature of 50°C, and a pH of 3.5, simultaneously apply mechanical stirring at 150 rpm and ultrasonic dispersion to perform diamond co-deposition electroplating for 60 minutes. By controlling the current density and stirring intensity, the exposure rate of diamond particles is controlled at 25%. Step 5: Perform stress-relief annealing on the electroplated workpiece at 150°C for 2 hours, followed by natural cooling to room temperature. Step 6: Electrolytically sharpen the annealed workpiece using a cutting tool as the anode and a stainless steel plate as the cathode. Anode dissolution and sharpening are performed in a dilute sulfuric acid electrolyte to obtain a diamond cutting tool.

[0081] Example 2: The electroplating preparation process of ultra-fine diamond cutting blades for ultra-thin wafer dicing in this example includes the following steps: Step 1: Take diamond particles with a particle size of 2-3 μm, wherein the single crystal ratio is 92% and the impurity content is 20 ppm; add them to dilute nitric acid with a volume fraction of 40% and soak them at room temperature for 3 hours to remove impurities on the particle surface. Then wash them with deionized water until neutral and dry them at 90°C to constant weight. Add the treated diamond particles to nickel sulfamate electroplating solution and ultrasonically disperse them at a frequency of 30 kHz for 30 minutes to break up the agglomerated diamond particles and suspend them uniformly in the electroplating solution. The composition of the nickel sulfamate electroplating solution is: nickel sulfamate 400 g / L, nickel chloride 20 g / L, boric acid 35 g / L, polyethylene glycol octylphenyl ether 0.1 g / L, the solvent is deionized water, and the pH value is adjusted to 4.0. Step Two: Using the cemented carbide blade ring substrate as the cathode, the following pretreatments were performed sequentially: alkaline degreasing (treatment with alkaline degreasing solution at 60℃ for 8 min); alkaline washing (treatment with 40 g / L sodium hydroxide solution at 60℃ for 8 min); ultrasonic cleaning (ultrasonic treatment with deionized water at 40 kHz for 3 min); acid washing (treatment with 8% (v / v) dilute hydrochloric acid for 2 min); activation (treatment with 15% (v / v) dilute sulfuric acid for 20 s); passivation (treatment with 2 g / L chromic acid solution for 8 s); the substrate surface was rinsed with deionized water after each step. Step Three: The treated substrate was placed in a nickel sulfamate electroplating solution of the same composition without diamond particles. High-purity nickel was used as the anode, and a polyester filter bag with a filtration accuracy of 20 μm was placed outside the anode. Pre-plating was performed for 6 min at a current density of 0.7 amperes per square decimeter to obtain a 1.5 μm thick nickel undercoat layer as a transition anchoring layer. Step 4: Transfer the pre-plated substrate into the electroplating solution containing diamond particles obtained in Step 1. Using high-purity nickel as the anode, and under conditions of a current density of 2.0 amperes per square decimeter, a temperature of 52°C, and a pH of 4.0, simultaneously apply mechanical stirring at 200 rpm and ultrasonic dispersion to perform diamond co-deposition electroplating for 50 minutes. By controlling the current density and stirring intensity, the exposure rate of diamond particles is controlled at 25%. Step 5: Perform stress-relief annealing on the electroplated workpiece at 180°C for 1 hour, followed by natural cooling to room temperature. Step 6: Mechanically sharpen the annealed workpiece by grinding the cutting edge with diamond polishing paste to obtain a diamond cutting tool.

[0082] Example 3: The electroplating preparation process of ultra-fine diamond cutting blades for ultra-thin wafer dicing in this example includes the following steps: Step 1: Take diamond particles with a particle size of 2.5 μm, wherein the single crystal ratio is 95% and the impurity content is 15 ppm; add them to dilute hydrochloric acid with a volume fraction of 50% and soak them at room temperature for 4 hours to remove impurities on the particle surface. Then wash them with deionized water until neutral and dry them at 100°C to constant weight. Add the treated diamond particles to nickel sulfamate electroplating solution and ultrasonically disperse them at a frequency of 35 kHz for 30 minutes to break up the agglomerated diamond particles and suspend them uniformly in the electroplating solution. The composition of the nickel sulfamate electroplating solution is: nickel sulfamate 450 g / L, nickel chloride 20 g / L, boric acid 40 g / L, hexadecyltrimethylammonium bromide 0.15 g / L, the solvent is deionized water, and the pH value is adjusted to 4.5. Step Two: Using the stainless steel blade ring substrate as the cathode, the following pretreatments were performed sequentially: alkaline degreasing (treatment with alkaline degreasing solution at 70℃ for 5 min); alkaline washing (treatment with 50 g / L sodium hydroxide solution at 70℃ for 5 min); ultrasonic cleaning (ultrasonic treatment with deionized water at 50 kHz for 5 min); acid washing (treatment with 10% (v / v) dilute hydrochloric acid for 1 min); activation (treatment with 20% (v / v) dilute sulfuric acid for 10 s); passivation (treatment with 3 g / L chromic acid solution for 5 s); the substrate surface was rinsed with deionized water after each step. Step Three: The treated substrate was placed in a nickel sulfamate electroplating solution of the same composition without diamond particles. High-purity nickel was used as the anode, and a polyester filter bag with a filtration accuracy of 10 μm was placed outside the anode. Pre-plating was performed for 5 min at a current density of 0.8 amperes per square decimeter to obtain a nickel undercoat layer with a thickness of 1.8 μm, serving as a transition anchoring layer. Step 4: Transfer the pre-plated substrate into the electroplating solution containing diamond particles obtained in Step 1. Using high-purity nickel as the anode, and under conditions of a current density of 2.2 amperes per square decimeter, a temperature of 55°C, and a pH of 4.5, simultaneously apply mechanical stirring at 250 rpm and ultrasonic dispersion to perform diamond co-deposition electroplating for 45 minutes. By controlling the current density and stirring intensity, the exposure rate of diamond particles is controlled at 25%. Step 5: Perform stress-relief annealing on the electroplated workpiece at 200°C for 0.5 hours, followed by natural cooling to room temperature. Step 6: Electrolytically sharpen the annealed workpiece using a cutting tool as the anode and a stainless steel plate as the cathode. Anode dissolution and sharpening are performed in a dilute sulfuric acid electrolyte to obtain a diamond cutting tool.

[0083] Comparative Example 1: The specific steps of this comparative example are as follows: Step 1: Diamond particles with a diameter of 10-20 μm were taken and added directly to the Watt's nickel plating solution without acid washing or purification, and without ultrasonic dispersion. The composition of the Watt's nickel plating solution was: 250 g / L nickel sulfate, 45 g / L nickel chloride, 40 g / L boric acid, and a pH of 5.0. Step 2: The stainless steel substrate was subjected to conventional degreasing and acid washing treatment, without ultrasonic cleaning or passivation treatment. Step 3: The pre-plating step was omitted, and the substrate was directly transferred into the diamond-containing plating solution. Using nickel as the anode, co-deposition electroplating was performed at a current density of 3.0 amperes per square decimeter and a temperature of 45°C. The stirring speed was 100 rpm, and the plating time was 60 min. Step 4: The stress-relief annealing step was omitted, and mechanical sharpening was performed directly to obtain the diamond cutting tool.

[0084] The blades prepared in Examples 1-3 and Comparative Example 1 were subjected to performance tests, and the test results are as follows: Figure 2 As shown, Example 3 is the optimal one.

[0085] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing, characterized in that, Includes the following steps: Step 1: Add diamond particles with a particle size of 1-5 micrometers to the nickel aminosulfonate electroplating solution and disperse them ultrasonically at a frequency of 20-40kHz to break up the agglomerated diamond particles and suspend them uniformly in the electroplating solution. Step 2: Using the stainless steel or cemented carbide blade ring substrate as the cathode, perform degreasing, alkaline washing, acid washing and activation treatment in sequence. Step 3: The substrate treated in Step 2 is placed in a nickel sulfamate electroplating solution that does not contain diamond particles. The nickel sulfamate electroplating solution that does not contain diamond particles has the same composition as the nickel sulfamate electroplating solution in Step 1. High-purity nickel is used as the anode, and a nickel undercoating layer with a thickness of 1-2 micrometers is pre-plated under a current density of 0.5-1.0 A / dm^2. The nickel undercoating layer serves as a transition anchoring layer. Step four: The substrate pre-plated in step three is transferred into the electroplating solution containing diamond particles obtained in step one. High-purity nickel is used as the anode. Under the conditions of current density of 1.5-2.5 A / dm^2, temperature of 50-55 degrees Celsius, and pH value of 3.50-4.50, mechanical stirring and ultrasonic dispersion are applied simultaneously to perform diamond co-deposition electroplating. The current density is higher than the current density of the pre-plating in step three. The exposure rate of diamond on the coating surface is controlled by adjusting the current density and mechanical stirring intensity, so that diamond particles and nickel coating are co-deposited on the substrate surface to form a cutting edge. Step 5: Perform stress-relief annealing on the workpiece after electroplating in Step 4 at a temperature of 150-200 degrees Celsius for 0.5-2 hours. Step 6: Perform mechanical or electrolytic sharpening on the workpiece after annealing in Step 5.

2. The electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing according to claim 1, characterized in that, The diamond particles mentioned in step one have a single crystal ratio greater than or equal to 90% and an impurity content less than or equal to 25 ppm. The diamond particles are acid-washed and purified before being added to the nickel sulfamate electroplating solution. The acid-washing and purification treatment uses a 30%-50% volume fraction of dilute hydrochloric acid or dilute nitric acid solution to soak the diamond particles at room temperature for 2-4 hours. After treatment, the particles are washed with deionized water until neutral and dried at 80-100 degrees Celsius to constant weight.

3. The electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing according to claim 2, characterized in that, The diamond particles in step one have a particle size of 2-3 micrometers, a single crystal ratio of 92% or higher, an impurity content of 20 ppm or lower, and an ultrasonic dispersion frequency of 25-35 kHz.

4. The electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing according to claim 1, characterized in that, In step two, an ultrasonic cleaning step is added after alkaline washing and before acid washing. The ultrasonic cleaning uses deionized water, the ultrasonic frequency is 30-50kHz, and the cleaning time is 2-5min. After activation, a passivation treatment step is added. The passivation treatment uses a chromic acid solution with a concentration of 1-3g / L for 5-10s.

5. The electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing according to claim 1, characterized in that, The pre-plating in step three is carried out under the condition of current density of 0.6-0.8A / dm^2, the pre-plating time is 3-8min, and the thickness of the nickel undercoat is 1.2-1.8 micrometers.

6. The electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing according to claim 5, characterized in that, In step three, a polyester filter bag is installed outside the high-purity nickel anode. The polyester filter bag is used to trap the anode mud generated by anode dissolution. The filtration accuracy of the polyester filter bag is 10-25 micrometers.

7. The electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing according to claim 6, characterized in that, The current density of the co-deposition electroplating in step four is 1.8-2.2 A / dm^2, and the difference between the current density of the co-deposition electroplating and the current density of the pre-plating in step three (0.6-0.8 A / dm^2) is 1.0-1.6 A / dm^2.

8. The electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing according to claim 1, characterized in that, In the nickel sulfamate electroplating solution described in step one and the nickel sulfamate electroplating solution without diamond particles described in step three, the concentration of nickel sulfamate is 300-450 g / L, the concentration of nickel chloride is 20 g / L, the concentration of boric acid is 30-40 g / L, the concentration of surfactant is 0.05-0.2 g / L, the solvent is deionized water, and the pH value of the electroplating solution is adjusted to 3.50-4.50 using dilute hydrochloric acid or dilute ammonia.

9. The electroplating process for preparing ultra-fine diamond cutting blades for ultra-thin wafer dicing according to claim 8, characterized in that, The surfactant is selected from sodium dodecyl sulfate, polyethylene glycol octylphenyl ether, or hexadecyltrimethylammonium bromide, and the concentration of the surfactant in the electroplating solution is 0.08-0.15 g / L.

10. The electroplating process for preparing ultra-fine-grained diamond cutting blades for ultra-thin wafer dicing according to claim 1, characterized in that, In step four, the diamond exposure rate on the coating surface is increased by reducing the current density to 1.5-1.8 A / dm² and weakening the mechanical stirring intensity to 100-150 rpm, and the diamond exposure rate on the coating surface is decreased by increasing the current density to 2.2-2.5 A / dm² and strengthening the mechanical stirring intensity to 200-300 rpm, wherein the exposure rate is 20%-30%.

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