Ceramic substrate with low-stress composite copper plating layer and method for manufacturing the same

Abstract

The application belongs to the technical field of electronic packaging and specifically relates to a ceramic substrate containing a low-stress composite copper plating layer and a preparation method thereof. The application also provides a preparation method of the ceramic substrate containing the low-stress composite copper plating layer, that is, a composite metal layer is deposited on a ceramic substrate by using a composite electroplating technology, the process is simple, the cost is low, the internal structure of the prepared composite plating layer is dense, the stress is small, the thermal conductivity of the ceramic substrate is improved, and the warping of the ceramic substrate is reduced. Experiments show that the thermal conductivity of the composite plating layer can be increased to more than 600 W / (m·K), the stress can be reduced from 130.3 MPa of a pure copper plating layer to -3.0 MPa, the heat conduction capacity of the DPC ceramic substrate is greatly improved, and the stress of the DPC ceramic substrate is significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of electronic packaging technology, specifically relating to a ceramic substrate containing a low-stress composite copper plating layer and its preparation method. Background Technology

[0002] Directly plated copper ceramic substrates (DPCs) are widely used in power semiconductor device packaging due to their advantages such as low-temperature fabrication, high patterning precision, controllable circuit layer thickness, and vertical interconnect capability. With increasing chip power density and ever-growing device reliability requirements, various thick copper structures, such as dammed cavities, thick copper lines, and microfluidic channels, need to be fabricated on the ceramic substrate surface to meet packaging application demands. However, due to the significant difference in thermal expansion coefficients between metallic copper and the ceramic substrate, DPC ceramic substrates with thick copper structures suffer from high stress and warping, affecting subsequent packaging quality. Furthermore, the thermal conductivity of pure metal materials cannot meet the heat dissipation requirements of power device packaging, necessitating novel high thermal conductivity materials to enhance heat dissipation. Simultaneously, the large copper layer thickness on the DPC substrate surface and the slow rate of existing electroplating deposition techniques significantly impact the fabrication efficiency of DPC ceramic substrates.

[0003] Metal matrix composites use metals and their alloys as the matrix, adding fibers, whiskers, or particles as reinforcing phases to achieve specific or improved overall properties, meeting diverse application requirements. Metal matrix composite thin film materials, in particular, can serve as hard and lubricating films to provide protection as a substrate material, and can also function as films with excellent mechanical, optical, electrical, and magnetic properties, making them widely applicable. Diamond particles possess high thermal conductivity, high strength, high modulus, excellent wear resistance, and chemical stability, making them a reinforcing phase material with excellent comprehensive properties. Furthermore, diamond particles have a wide particle size range; nano-sized diamond particles exhibit surface and size effects, further enhancing the physical properties of the composite material; micron-sized diamond particles have high thermal conductivity, significantly increasing the thermal conductivity of the composite material and meeting the needs of various applications. Adding both types of diamond particles simultaneously to an electroplating solution results in electroplated composite materials with even better physical properties and thermal conductivity, making them an ideal choice for next-generation packaging materials.

[0004] Currently, composite electroplating is the main method for preparing copper-based composite materials. It is a highly efficient, economical, low-temperature, and controllable processing technology. Furthermore, composite electroplating technology is highly applicable and can be used on the surfaces of various conductive materials. By adding diamond particles to the electroplating solution and co-depositing them with copper cations at the cathode, a copper-based composite coating with a ceramic particle reinforcement phase is formed. During the deposition process, the addition of the diamond particle reinforcement phase affects the grain growth pattern, and the internal stress of the composite coating is significantly reduced compared to pure metal coatings. In addition, the content of the diamond particle reinforcement phase also affects the performance of the composite coating. By changing the process parameters and adjusting the content of the reinforcement phase, composite coatings with various properties can be obtained. By adjusting the diamond particle size, the thermal conductivity of the composite coating can be controlled, improving the physical properties of the composite material (coefficient of thermal expansion, thermal conductivity, hardness, toughness, etc.). By combining pattern electroplating with composite plating technology, various complex microstructures can also be prepared to meet the application requirements of power device packaging.

[0005] In summary, replacing pure copper plating with copper-based diamond composite coating is an ideal method to improve thermal conductivity and reduce stress. However, existing electroplating technologies suffer from numerous interface defects, resulting in composite material conductivity that is far lower than the theoretical value and reduced reliability after heating. Furthermore, existing technologies for preparing composite coatings are inefficient, limiting their large-scale application. Summary of the Invention

[0006] To address the problems of low thermal conductivity, high stress, easy warping, and low fabrication efficiency of existing DPC ceramic substrates, this invention provides a ceramic substrate with a low-stress composite copper plating layer and its fabrication method. The purpose of this invention is to provide a method for preparing a composite copper plating layer with high electroplating rate, high thermal conductivity, and high processing efficiency, as well as the required process parameters, to obtain a high-performance, low-warping DPC ceramic substrate.

[0007] This invention provides a ceramic substrate containing a low-stress composite copper plating layer, comprising a composite copper plating layer and a ceramic substrate. The composite copper plating layer is fixed on the ceramic substrate and is composed of electroplated copper and diamond particles. The thickness of the composite copper plating layer is 60-600 μm. The diamond particles are a mixture of diamond particles with a particle size of 0.01-10 μm and diamond particles with a particle size of 10-100 μm, wherein the weight ratio of the diamond particles with a particle size of 0.01-10 μm to the diamond particles with a particle size of 10-100 μm is 2-5:1.

[0008] Furthermore, diamond possesses high thermal conductivity, low coefficient of thermal expansion, high strength, high modulus, excellent wear resistance, and chemical stability, making it a reinforcing phase material with superior comprehensive performance. Diamond particles have a wide particle size range; nano-sized diamond particles exhibit surface and size effects, enhancing the physical properties of the composite material and increasing the packing density of the composite copper plating layer while reducing void formation. Micron-sized diamond particles have higher thermal conductivity, significantly increasing the thermal conductivity of the composite material. In particular, the combined use of nano-sized and micron-sized diamond particles can effectively improve the packing density of the composite plating layer, reduce internal stress, and increase thermal conductivity, while also improving the electroplating rate.

[0009] Furthermore, the diamond particles are metal-pretreated or untreated diamond particles, wherein the metal-pretreated diamond particles are electroless nickel-plated or copper-plated diamond particles, and the untreated diamond particles are pure diamond particles.

[0010] Furthermore, diamond particles with a particle size of 0.01-10 μm are more preferably 0.01-1 μm, and diamond particles with a particle size of 10-100 μm are more preferably 30-80 μm.

[0011] This invention also provides a method for preparing a ceramic substrate containing a low-stress composite copper plating layer, the steps of which are as follows:

[0012] 1) Pretreatment of diamond particles: The diamond particles are subjected to multiple ultrasonic deionized water washing, alkali washing, hydrochloric acid washing, and ultrasonic deionized water washing steps to remove impurities from the particle surface, and then dried for later use.

[0013] 2) Prepare a composite copper plating solution by adding electroplating additives and diamond particles to the base copper plating solution and mixing the above components evenly through a stirring process.

[0014] 3) Pre-treat the ceramic substrate by removing impurities, removing the oxide layer, and roughening the surface;

[0015] 4) Circuit patterns are prepared on the surface of a ceramic substrate using processes such as sputtering seed layer, dry film lamination, exposure, and development;

[0016] 5) Place the ceramic substrate in the composite electroplating solution, stir the electroplating solution, and deposit the composite electroplating layer after applying electricity. Repeat steps 4)-5) until the composite coating reaches the required thickness.

[0017] 6) Remove the dry film and seed layer, clean and dry to obtain a ceramic substrate containing a composite copper plating layer.

[0018] Furthermore, the basic copper plating solution in the composite copper plating solution described in step 2) above consists of: copper sulfate pentahydrate 120-200 g / L, sulfuric acid 50-120 g / L, and chloride ions 50-80 mg / L.

[0019] Furthermore, the electroplating additive mentioned in step 2) includes a dispersant, an inhibitor, an accelerator, and a leveling agent. The dispersant is one or a mixture of several of octadecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and tetradecylpyridine bromide, with a total concentration of 10–50 mg / L.

[0020] The inhibitor is one or a mixture of several polyethylene glycols (molecular weight 6000, 8000, 11000), with a total concentration of 200-300 mg / L;

[0021] The accelerator is one or a mixture of several of the following: sodium thiazolinyl dithiopropane sulfonate, sodium polydithiopropane sulfonate, and sodium 3-mercapto-1-propane sulfonate, with a total concentration of 6 to 12 mg / L.

[0022] The leveling agent is one or a mixture of several of 2-mercaptothiazoline, 2-mercaptopyridine, and nitrotetrazole blue chloride, with a total concentration of 2-10 mg / L.

[0023] Furthermore, the diamond particles are allowed to undergo surface metallization treatments, including but not limited to one or all of electroless nickel plating and copper plating.

[0024] Furthermore, the concentration of diamond particles in the composite copper plating solution described in step 2) is 0.2-30 g / L; preferably, after surface metallization treatment, a lower concentration of diamond particles (0.2-5 g / L) should be selected. Furthermore, the size of the diamond particles in the composite copper plating solution described in step 2) above has a regulating effect on the thermal conductivity of the coating; preferably, to improve the thermal conductivity of the coating, diamond particles with a particle size of 30-80 μm should be selected.

[0025] Furthermore, a mixture of diamond particles with a diameter of 0.01-10 μm and diamond particles with a diameter of 10-100 μm is used, wherein the weight ratio of the 0.01-10 μm diamond particles to the 10-100 μm diamond particles is 2-5:1. Combining diamond particles of different sizes can improve thermal conductivity and packing density, thereby enhancing the overall performance of the composite coated ceramic substrate.

[0026] Furthermore, the stirring method and intensity during the electrodeposition process described in step 5) are related to the diamond particle size;

[0027] Preferably, diamond particles with a particle size of 0.01-10μm are stirred by ultrasonic and air agitation, with an ultrasonic frequency of 20-30kHz and an air flow rate of 0.6-1.6L / min.

[0028] Preferably, diamond particles with a particle size of 10-100μm are stirred magnetically with a rotor speed of 150-300rpm.

[0029] Preferably, the diamond particles are mixed using ultrasonic and magnetic stirring, with an ultrasonic frequency of 15-20kHz and a magnetic rotor speed of 100-200rpm.

[0030] Furthermore, the stirring intensity has a regulatory effect on the doping amount of diamond particles. A lower stirring intensity is preferred to increase the doping amount, and vice versa. When the composite electroplating solution contains diamond particles with a particle size of 0.01-10μm and diamond particles with a particle size of 10-100μm, a combination of ultrasonic and magnetic stirring should be used, and the stirring intensity of each stirring method should be lower than the stirring intensity of the unmixed particle size.

[0031] Furthermore, the process parameters for the electrodeposition process in step 5) are: current density 4-10 ASD, electroplating solution temperature 20-30℃;

[0032] Preferably, the diamond particles for surface metallization treatment should have a plating current density increased by 50%, i.e., 6 to 15 ASD;

[0033] Preferably, the diamond particles without surface metallization treatment should have a plating current density reduced by 50%, i.e., 2 to 5 ASD.

[0034] Furthermore, the composite copper plating layer obtained by the preparation method of the present invention has a fast electroplating rate. Specifically, when using diamond particles without surface metallization treatment, the electroplating rate is greater than 150 μm / h; when using diamond particles with surface metallization treatment, the electroplating rate is greater than 200 μm / h.

[0035] The main beneficial technical effects of this invention are as follows:

[0036] 1) This invention provides a method for preparing a ceramic substrate with a low-stress composite copper plating layer. The method involves depositing a composite metal layer on a ceramic substrate using composite electroplating technology. This process is simple, low-cost, and produces a dense composite plating layer with low stress, thereby improving the thermal conductivity of the ceramic substrate while reducing warpage. Experiments show that the thermal conductivity of the composite plating layer can be increased to over 600 W / (m·K), and the stress can be reduced from 130.3 MPa for pure copper plating to -3.0 MPa, significantly improving the thermal conductivity of the DPC ceramic substrate and substantially reducing its stress.

[0037] (2) This invention provides a novel high-speed composite copper material electroplating formulation: including an accelerator component to improve the limiting current density, an inhibitor component to promote surface wetting, a leveling agent component to improve the uniformity of the composite coating, and a dispersant component to promote the uniform dispersion of diamond particles; the dispersant is preferably a long-chain nitrogen-containing organic compound carrying a positive charge, which can further improve the stability of the plating solution and the limiting current density by forming a synergistic effect with other additives, promote the uniform adsorption of particles on the cathode surface, ensure the uniform distribution of particles in the composite coating, and at the same time increase the range of current density that can be applied to the composite coating, significantly improve the deposition rate of the composite coating (greater than 150 μm / h), and meet the requirements for the preparation of thick coatings.

[0038] (3) This invention uses a mixture of diamond particles with a particle size of 0.01-10 μm and diamond particles with a particle size of 10-100 μm, wherein the weight ratio of the diamond particles with a particle size of 0.01-10 μm to the diamond particles with a particle size of 10-100 μm is 2-5:1. The combination of diamond particles with different particle sizes can improve thermal conductivity and packing density, thereby improving the overall performance of the composite coated ceramic substrate. Attached Figure Description

[0039] Figure 1 These are scanning electron microscope (SEM) images of the surface and cross-section of the composite copper plating layer in Embodiment 1 of the present invention, used to characterize the plating quality;

[0040] Figure 2 This is a scanning electron microscope image of the composite copper plating layer surface in Embodiment 2 of the present invention, used to characterize the plating quality;

[0041] Figure 3 This is a diagram showing the warping offset of the substrate containing the composite copper-plated dam in Embodiment 3 of the present invention.

[0042] Figure 4 This is a scanning electron microscope (SEM) image of the cross-section of the composite copper plating layer in Embodiment 4 of the present invention.

[0043] Figure 5 This is a scanning electron microscope (SEM) image of the cross-section of the composite copper plating layer in Embodiment 5 of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the following description, in conjunction with embodiments and the appendix, is provided. Figure 1-3 The present invention will be further described in detail below. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and is not intended to limit the invention.

[0045] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. A composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0046] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0047] In some instances, approximate terms may correspond to the precision of the instrument used to measure the value. In this specification and claims, scope definitions may be combined and / or interchanged. Unless otherwise stated, these scopes include all subscopes contained therein.

[0048] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0049] The terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" used in this invention refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example. Furthermore, the technical features involved in the various embodiments of the invention can be combined with each other as long as they do not conflict with each other.

[0050] Unless otherwise specified, the raw materials and equipment used in this invention can be purchased from the market or are commonly used in the field. Unless otherwise specified, the methods in the embodiments are conventional methods in the field.

[0051] The present invention is further described below with reference to specific embodiments:

[0052] Example 1

[0053] Example 1 achieved high-speed preparation of low-stress copper composite coating, with the thermal conductivity of the composite copper coating increased to 432 W / (m·K) and the electroplating rate being 165 μm / h.

[0054] The main preparation process is as follows: Select diamond particles with a particle size of 1μm that have not undergone surface metallization treatment. Pre-treat the diamond particles to remove impurities such as metal and oxide layers from the surface. Place the diamond particles in deionized water and ultrasonically clean them for 10 minutes, repeating 2-3 times. Then, immerse the diamond particles in hydrochloric acid solution and heat to boiling (50℃), maintaining for 40 minutes. After acid washing, place the diamond particles in deionized water and ultrasonically clean them for 10 minutes, repeating 3-5 times. Next, immerse the diamond particles in sodium hydroxide solution and heat to boiling (110℃), maintaining for 40 minutes. After immersion, ultrasonically clean them for 10 minutes, repeating 3-5 times. After cleaning, place the diamond particles in an oven and bake at 150℃ for 2 hours. After drying, they are ready for use.

[0055] Prepare a copper-diamond particle composite plating solution with the following proportions: 120 g / L copper sulfate pentahydrate, 60 mg / L chloride ions, 50 g / L sulfuric acid, 300 mg / L polyethylene glycol (molecular weight 8000), 6 mg / L sodium thiazolinyl dithiopropane sulfonate, 30 mg / L hexadecyltrimethylammonium bromide, 30 g / L diamond particles, and the balance being deionized water.

[0056] Preparation method of composite plating solution: Add an appropriate amount of deionized water to the electroplating tank, then add the base plating solution copper sulfate pentahydrate, polyethylene glycol (molecular weight 8000), sodium thiazolinyl dithiopropane sulfonate, and hexadecyltrimethylammonium bromide in sequence. Then add diamond particles (after removing impurities) to form a composite electroplating solution. Stir the composite electroplating solution with a magnetic stirrer for 30 minutes at 800 rpm. Then, ultrasonically disperse the solution for 15 minutes at a frequency of 20 kHz. Repeat the magnetic stirring and ultrasonic dispersion three times to ensure the diamond particles are evenly dispersed in the solution. Finally, pour the composite plating solution into the electroplating tank and aerate it at a flow rate of 2 L / min to obtain the copper-diamond composite electroplating solution.

[0057] The electrode plate is pretreated and includes an anode phosphor bronze plate and a cathode ceramic substrate.

[0058] The anode phosphor bronze plate was polished to a uniform and bright finish using metallographic sandpaper. The cathode was a ceramic substrate, which was an alumina ceramic sheet with a sputtered seed layer (Ti and Cu) of approximately 1 μm in total thickness. The ceramic substrate underwent sequential degreasing and oxide film removal, surface roughening, and activation treatments. The pretreatment steps for the cathode ceramic substrate were as follows: First, the cathode was ultrasonically cleaned with deionized water for 5 minutes to remove soluble impurities; then, degreasing and oxide film were removed, followed by immersion in a 5% sulfuric acid solution for 1-5 minutes; next, surface roughening was performed by immersion in a mixed solution of 10% sulfuric acid and 50 g / L sodium persulfate for 0.5-1 minutes; finally, surface activation was performed by immersion in a 12% sulfuric acid solution for 1 minute.

[0059] A copper-diamond composite coating was prepared by electroplating with a prepared composite electroplating solution. The phosphor bronze anode was placed vertically on both sides of the electroplating tank, and the ceramic substrate cathode was placed vertically in the middle of the electroplating tank, keeping parallel to the anode plates on both sides.

[0060] Composite electroplating was performed using direct current electrodeposition at a current density of 5 ASD, a deposition temperature of 25℃, an ultrasonic vibration frequency of 20 kHz, and a plating time of 1.5 h.

[0061] The prepared copper-diamond composite coating was ultrasonically cleaned with deionized water for 10 minutes, repeated 2-3 times, and then dried in an oven at 120℃ for 0.5 hours.

[0062] As attached Figure 1 The copper-diamond composite coating prepared by high-speed electroplating has a uniform thickness, a small number of protruding particles on the surface, and a dense internal structure without microscopic defects. The composite electroplating deposition rate is 165 μm / h, and the average coating thickness is approximately 240 μm. The coating stress decreases from 130.3 MPa in the pure copper coating to -3.0 MPa, approaching stress-free levels. The average shear strength of the composite coating is 18.1 MPa, and the average offset of the composite coating decreases from 635.2 μm in the pure copper coating to 206.3 μm, a decrease of 67.5%. The thermal conductivity increases from 386 W / (m·K) in the pure copper layer to 432 W / (m·K), an increase of 11.9%.

[0063] Example 2

[0064] Example 2 uses surface-metallized diamond particles with a particle size of 20 μm. Compared to Example 1, this example further increases the thermal conductivity of the copper-diamond composite coating to 615 W / (m·K) and improves the electroplating rate to 227 μm / h.

[0065] This embodiment 2 is basically the same as the method in embodiment 1 above. The difference is that the component concentration, diamond particle size, diamond particle surface treatment process, and electroplating process parameters for preparing the composite copper plating solution in embodiment 2 are as follows:

[0066] The composition of the copper-diamond composite plating solution is as follows: copper sulfate pentahydrate 150g / L, chloride ions 70mg / L, sulfuric acid 80g / L, polyethylene glycol (molecular weight 6000, molecular weight 8000) 260mg / L, sodium polydisulfide dipropane sulfonate 4mg / L, 2-mercaptothiazoline 3mg / L, octadecyltrimethylammonium bromide 25mg / L, diamond particles 2g / L, and the balance being deionized water.

[0067] The preparation method of the composite electroplating solution is as follows: Add an appropriate amount of deionized water to the electroplating tank, then sequentially add the base plating solution (copper sulfate pentahydrate), polyethylene glycol (molecular weight 6000, molecular weight 8000), sodium polydisulfide dipropane sulfonate, dimercaptothiazoline, and octadecyltrimethylammonium bromide. Next, add diamond particles (for surface chemical copper plating to remove impurities) to form the composite electroplating solution. Stir the composite electroplating solution using a magnetic stirrer for 30 minutes at a speed of 800 rpm. Then, ultrasonically disperse the solution for 15 minutes at a frequency of 25 kHz. Repeat the magnetic stirring and ultrasonic dispersion three times to ensure the diamond particles are uniformly dispersed in the solution. Finally, pour the composite plating solution into the electroplating tank and magnetically stir at a speed of 200 rpm to obtain the copper-diamond composite electroplating solution.

[0068] The electrode pretreatment method is the same as in Example 1.

[0069] A copper-diamond composite coating was prepared by electroplating with a prepared composite electroplating solution. The phosphor bronze anode was placed vertically on both sides of the electroplating tank, and the ceramic substrate cathode was placed vertically in the middle of the electroplating tank, keeping parallel to the anode plates on both sides.

[0070] Composite electroplating was performed using direct current electrodeposition at a current density of 10 ASD, a deposition temperature of 25℃, a magnetic stirring speed of 200 rpm, and a plating time of 1.5 h.

[0071] The cleaning method for the composite coating is the same as in Example 1.

[0072] See attached Figure 2 As shown, the copper / diamond composite coating prepared in the experiment has a uniform thickness, a small number of protruding particles on the surface, and a relatively dense coating. The composite electroplating deposition rate is as high as 216 μm / h. The internal stress of the coating is significantly reduced from 130.3 MPa in the pure copper coating to 15.4 MPa, and the average offset of the composite coating is reduced from 635.2 μm in the pure copper coating to 337.8 μm, a decrease of 46.8%. The thermal conductivity increases from 386 W / (m·K) in the pure copper layer to 635 W / (m·K), an increase of 64.5%.

[0073] Example 3

[0074] Example 3 is basically the same as Example 1, except that Example 3 adds a pattern transfer step and multiple electroplating thickening processes, using composite electroplating technology to complete the preparation of thick copper dams, as detailed below:

[0075] The diamond particles had a diameter of 1 μm, and the pretreatment method was the same as in Example 1.

[0076] A copper-diamond composite electroplating solution was prepared with the following composition: 120 g / L copper sulfate pentahydrate, 60 mg / L chloride ions, 50 g / L sulfuric acid, 300 mg / L polyethylene glycol (molecular weight 8000, molecular weight 11000), 6 mg / L sodium thiazolinyl dithiopropane sulfonate, 30 mg / L sodium dodecyl sulfate, 20 g / L diamond particles, and the balance being deionized water.

[0077] The preparation method of the copper-diamond particle composite electroplating solution is the same as in Example 1.

[0078] A seed layer was deposited on the surface of a ceramic substrate using a sputtering process.

[0079] The ceramic substrate surface pattern transfer is completed using photolithography and development processes. The pattern transfer method is as follows: a certain thickness of photoresist (dry film) is applied to the seed layer, and then the mask of the pattern to be deposited is tightly attached to the photoresist (dry film). After the required time of deep ultraviolet exposure, the photolithography process is completed. Subsequently, the ceramic substrate is immersed in a 10% sodium carbonate solution for the required time to complete the development process.

[0080] The electrode pretreatment method and electroplating method are the same as in Example 1.

[0081] The electrodeposition process parameters are: current density of 8 ASD, deposition temperature of 25℃, and ultrasonic frequency of 20kHz, to obtain a high-strength, low-stress copper-diamond composite coating.

[0082] The pattern transfer, electrode pretreatment, and electroplating processes were repeated multiple times until the thickness of the copper-diamond composite coating dam was 800 μm.

[0083] The cleaning method for the composite coating is the same as in Example 1.

[0084] The experimentally prepared copper-diamond composite coating exhibited uniform thickness, high pattern precision, and dense structure. The composite electroplating deposition rate was 130 μm / h, and the coating stress decreased from 130.3 MPa for the pure copper coating to 2.2 MPa. The average shear strength of the composite coating was 16.8 MPa, and the average offset of the composite coating decreased from 635.2 μm for the pure copper coating to 156.3 μm, a reduction of 75.4%. The thermal conductivity increased from 386 W / (m·K) for the pure copper layer to 429 W / (m·K), an increase of 11.1%.

[0085] Example 4

[0086] Example 4 uses mixed diamond particles with particle sizes of 1 μm and 60 μm, in a mass ratio of 2:1. Compared to Example 1, this example increases the thermal conductivity of the copper-diamond composite coating to 659 W / (m·K), reduces substrate warpage by 15%, and achieves an electroplating deposition rate of 195 μm / h.

[0087] This embodiment 4 is basically the same as the method in embodiment 1 above. The difference is that the component concentration, diamond particle size, diamond particle surface treatment process, and electroplating process parameters for preparing the composite copper plating solution in embodiment 4 are as follows:

[0088] The composition of the copper-diamond composite plating solution is as follows: copper sulfate pentahydrate 150 g / L, chloride ions 50 mg / L, sulfuric acid 80 g / L, polyethylene glycol (molecular weight 6000, molecular weight 8000) 300 mg / L, sodium polydisulfide dipropane sulfonate 4 mg / L, 2-mercaptothiazoline 3 mg / L, octadecyltrimethylammonium bromide 30 mg / L, 1 μm diamond particles 4 g / L, 60 μm diamond particles 2 g / L, and the balance is deionized water.

[0089] The method for preparing the composite electroplating solution is as follows: Add an appropriate amount of deionized water to the electroplating tank, then sequentially add the base plating solution (copper sulfate pentahydrate), polyethylene glycol (molecular weight 6000, molecular weight 8000), sodium polydisulfide dipropane sulfonate, dimercaptothiazoline, and octadecyltrimethylammonium bromide. Next, add mixed diamond particles (after removing impurities) to form the composite electroplating solution. Then, stir the composite electroplating solution using a magnetic stirrer for 30 minutes at a speed of 800 rpm. Next, ultrasonically disperse the solution for 15 minutes at an ultrasonic frequency of 20 kHz. Repeat the magnetic stirring and ultrasonic dispersion three times to ensure the diamond particles are uniformly dispersed in the solution. Finally, pour the composite plating solution into the electroplating tank, and combine ultrasonic vibration and magnetic stirring (ultrasonic vibration frequency 20 kHz, magnetic stirring speed 200 rpm) to obtain a copper-diamond composite electroplating solution with mixed particle sizes.

[0090] The electrode pretreatment method is the same as in Example 1.

[0091] A copper-diamond composite coating was prepared by electroplating with a prepared composite electroplating solution. The phosphor bronze anode was placed vertically on both sides of the electroplating tank, and the ceramic substrate cathode was placed vertically in the middle of the electroplating tank, keeping parallel to the anode plates on both sides.

[0092] Composite electroplating was performed using direct current electrodeposition with a current density of 8 ASD, a deposition temperature of 25℃, an ultrasonic vibration frequency of 20 kHz, a magnetic stirring speed of 200 rpm, and an electroplating time of 1.5 h.

[0093] The cleaning method for the composite coating is the same as in Example 1.

[0094] See attached Figure 4 As shown, the copper / diamond composite coating particles prepared in the experiment were uniformly mixed in the copper matrix, the coating was dense, and the composite electroplating deposition rate was as high as 195 μm / h. The internal stress of the coating was significantly reduced from 130.3 MPa in the pure copper coating to 13.9 MPa, and the average offset of the composite coating was reduced from 635.2 μm in the pure copper coating to 287.1 μm, a decrease of 54.8%. The thermal conductivity increased from 386 W / (m·K) in the pure copper layer to 659 W / (m·K), an increase of 70.7%.

[0095] Example 5

[0096] Example 5: High-speed preparation of copper-based silicon carbide composite coating. The thermal conductivity of the composite copper coating is only 275 W / (m·K), and the electroplating rate is 127 μm / h.

[0097] Preparation process: Select silicon carbide particles with a particle size of 1μm that have not undergone surface metallization treatment, ultrasonically clean them with deionized water, dry them, soak them in hydrofluoric acid for 1 hour, and finally clean them with deionized water and dry them for later use.

[0098] Prepare a copper-silicon carbide particle composite plating solution with the following composition: copper sulfate pentahydrate 120 g / L, chloride ions 60 mg / L, sulfuric acid 50 g / L, polyethylene glycol (molecular weight 8000) 300 mg / L, sodium thiazolinyl dithiopropane sulfonate 6 mg / L, hexadecyltrimethylammonium bromide 30 mg / L, silicon carbide particles 30 g / L, and the balance being deionized water.

[0099] Preparation method of composite plating solution: Add an appropriate amount of deionized water to the electroplating tank, then add the base plating solution copper sulfate pentahydrate, polyethylene glycol (molecular weight 8000), sodium thiazolinyl dithiopropane sulfonate, and hexadecyltrimethylammonium bromide in sequence. Then add silicon carbide particles (after removing impurities) to form a composite electroplating solution. Stir the composite electroplating solution with a magnetic stirrer for 30 minutes at 800 rpm. Then, ultrasonically disperse the solution for 15 minutes at a frequency of 20 kHz. Repeat the magnetic stirring and ultrasonic dispersion three times to ensure that the silicon carbide particles are uniformly dispersed in the solution. Finally, pour the composite plating solution into the electroplating tank and aerate it at a flow rate of 2 L / min to obtain the copper-silicon carbide composite electroplating solution.

[0100] The electrode plate is pretreated and includes an anode phosphor bronze plate and a cathode ceramic substrate.

[0101] The anode phosphor bronze plate was polished to a uniform and bright finish using metallographic sandpaper. The cathode was a ceramic substrate, which was an alumina ceramic sheet with a sputtered seed layer (Ti and Cu) of approximately 1 μm in total thickness. The ceramic substrate underwent sequential degreasing and oxide film removal, surface roughening, and activation treatments. The pretreatment steps for the cathode ceramic substrate were as follows: First, the cathode was ultrasonically cleaned with deionized water for 5 minutes to remove soluble impurities; then, degreasing and oxide film were removed, followed by immersion in a 5% sulfuric acid solution for 1-5 minutes; next, surface roughening was performed by immersion in a mixed solution of 10% sulfuric acid and 50 g / L sodium persulfate for 0.5-1 minutes; finally, surface activation was performed by immersion in a 12% sulfuric acid solution for 1 minute.

[0102] A copper-silicon carbide composite coating was prepared by electroplating using a prepared composite plating solution. The phosphor bronze anode was placed vertically on both sides of the electroplating tank, and the ceramic substrate cathode was placed vertically in the middle of the electroplating tank, keeping it parallel to the anode plates on both sides.

[0103] Composite electroplating was performed using direct current electrodeposition at a current density of 5 ASD, a deposition temperature of 25℃, an ultrasonic vibration frequency of 20 kHz, and a plating time of 1.5 h.

[0104] The prepared copper-silicon carbide composite coating was ultrasonically cleaned with deionized water for 10 minutes, repeated 2-3 times, and then dried in an oven at 120℃ for 0.5 hours.

[0105] As attached Figure 5 The copper-silicon carbide composite coating prepared by high-speed electroplating has uniform thickness, dense internal structure, and no microscopic defects. The composite electroplating deposition rate is 127 μm / h, and the average coating thickness is approximately 190 μm. The coating stress is reduced from 130.3 MPa for pure copper coating to 15.8 MPa, and the average offset of the composite coating is reduced from 635.2 μm for pure copper coating to 357.6 μm, a decrease of 43.7%. The thermal conductivity is reduced from 386 W / (m·K) for pure copper layer to 275 W / (m·K), a decrease of 28.8%.

[0106] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A ceramic substrate containing a low-stress composite copper plating layer, comprising a composite copper plating layer and a ceramic substrate, wherein the composite copper plating layer is fixed on the ceramic substrate, the composite copper plating layer is composed of electroplated copper and diamond particles, the thickness of the composite copper plating layer is 60-600 μm, the diamond particles are a mixture of diamond particles with a particle size of 0.01-10 μm and diamond particles with a particle size of 30-80 μm, and the weight ratio of the diamond particles with a particle size of 0.01-10 μm to the diamond particles with a particle size of 30-80 μm is 2-5:1; the composite copper plating layer is fixed on the ceramic substrate by depositing a composite metal layer on the ceramic substrate using a composite electroplating technology.

2. The ceramic substrate containing a low-stress composite copper plating layer according to claim 1, characterized in that, The diamond particles are metal-pretreated diamond particles, wherein the metal-pretreated diamond particles are chemically plated with nickel or copper.

3. A ceramic substrate containing a low-stress composite copper plating layer according to claim 1, characterized in that, The diamond particles are pure diamond particles.

4. A method for preparing a ceramic substrate containing a low-stress composite copper plating layer as described in any one of claims 1-3, wherein the preparation method comprises the following steps: 1) Pretreatment of diamond particles: The diamond particles are subjected to multiple ultrasonic deionized water washing, alkali washing, hydrochloric acid washing, and ultrasonic deionized water washing steps to remove impurities from the particle surface, and then dried for later use. 2) Prepare a composite copper plating solution by adding electroplating additives and diamond particles to the base copper plating solution and mixing the above components evenly through a stirring process. 3) The ceramic substrate is pretreated by removing impurities, removing the oxide layer, and roughening the surface; 4) A process of sputtering a seed layer, applying a dry film, exposure, and development is used to prepare circuit patterns on the surface of a ceramic substrate; 5) Place the ceramic substrate in the composite electroplating solution, stir the electroplating solution, and deposit the composite electroplating layer after applying electricity. Repeat steps 4)-5) until the composite coating reaches the required thickness. 6) Remove the dry film and seed layer, clean and dry to obtain a ceramic substrate containing a composite copper plating layer.

5. The method for preparing a ceramic substrate containing a low-stress composite copper plating layer according to claim 4, characterized in that, The basic copper plating solution in the composite copper plating solution in step 2) consists of: copper sulfate pentahydrate 120~200g / L, sulfuric acid 50~120g / L, and chloride ions 50~80mg / L.

6. The method for preparing a ceramic substrate containing a low-stress composite copper plating layer according to claim 4, characterized in that, The electroplating additive in step 2) comprises a dispersant, an inhibitor, an accelerator, and a leveling agent. The dispersant is one or more of octadecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and tetradecylpyridine bromide, with a concentration of 10-50 mg / L. The inhibitor is one or a mixture of one or more of polyethylene glycol 6000, polyethylene glycol 8000, and polyethylene glycol 11000, with a concentration of 200-300 mg / L. The accelerator is one or a mixture of one or more of thiazolinyl dithiopropane sulfonate, polydithiopropane sulfonate, and 3-mercapto-1-propane sulfonate, with a concentration of 6-12 mg / L. The leveling agent is one or a mixture of one or more of 2-mercaptothiazoline, 2-mercaptopyridine, and nitrotetrazole blue chloride, with a total concentration of 2-10 mg / L.

7. The method for preparing a ceramic substrate containing a low-stress composite copper plating layer according to claim 4, characterized in that, In step 2), the concentration of diamond particles in the composite copper plating solution is 0.2-30 g / L.

8. The method for preparing a ceramic substrate containing a low-stress composite copper plating layer according to claim 4, characterized in that, In step 2), the composite copper plating solution contains a mixture of diamond particles with a particle size of 0.01-10 μm and 30-80 μm.

9. The method for preparing a ceramic substrate containing a low-stress composite copper plating layer according to any one of claims 4-8, characterized in that, In step 5), the stirring method during electrodeposition is ultrasonic and magnetic stirring, with an ultrasonic frequency of 15-20kHz and a magnetic rotor speed of 100-200rpm.

10. The method for preparing a ceramic substrate containing a low-stress composite copper plating layer according to any one of claims 4-8, characterized in that, The process parameters for step 5) of electrodeposition are: current density 2~15 ASD, electroplating solution temperature 20-30℃.

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