A method for preparing a surface metallization coating for a dielectric filter

Abstract

The application provides a preparation method of a medium filter surface metallization coating, and comprises the following steps: a deposition process: a metal layer is deposited on the surface of a medium ceramic base by using a high-power magnetron sputtering technology; first, the peak current is increased by adjusting the frequency and pulse width of the high-power magnetron sputtering technology to obtain high-density plasma; then, the rotation speed of the medium ceramic base is reduced, and an auxiliary cathode is added behind the medium ceramic base to increase the directionality of plasma movement, so that columnar crystals with different inclination angles are obtained. The application has the beneficial effects that: according to the method, only a Cu metal layer needs to be deposited on the surface of the medium ceramic, the process of metallizing the surface of the medium ceramic is reduced, the production cost is greatly reduced, and the preparation process is relatively simple because a reducing gas does not need to be introduced during the preparation process.

Description

Technical Field

[0001] This invention relates to metallization coatings on ceramic surfaces, and more particularly to a method for preparing a metallization coating on the surface of a dielectric filter. Background Technology

[0002] Ceramic materials (including salt ceramics, silicon carbide, etc.) often require welding, etching circuits, or shielding in various applications. However, welding ceramic materials to metals often presents numerous challenges.

[0003] 1. Most ceramic materials are difficult to bond with metal layers, and the difference in their coefficients of thermal expansion is large, which can easily lead to problems such as separation, blistering, and cracking.

[0004] 2. For high thermal conductivity materials such as aluminum nitride, silicon carbide, and diamond, the best connection method between heating devices and cooling units is currently welding, such as gold-tin welding. However, the welding temperature is relatively high, and under high and low temperature shocks, the interface of materials with different thermal expansion coefficients is very easy to separate, causing failure and heat transfer failure.

[0005] 3. Most ceramics have poor electrical conductivity, or even no electrical conductivity at all, making them difficult to weld.

[0006] 4. Because ceramic materials are mostly covalent crystals, they are not easily deformed and often undergo brittle fracture. Currently, most methods utilize an intermediate layer to lower the welding temperature and employ indirect diffusion welding.

[0007] 5. The structural design of ceramic-metal welding differs from that of ordinary welding. It is usually divided into flat sealing structure, sleeve sealing structure, needle sealing structure and butt sealing structure. Among them, the sleeve sealing structure has the best effect. The manufacturing requirements of these joint structures are very high.

[0008] Therefore, it is necessary to metallize ceramic materials, that is, to apply a thin metal film that is firmly bonded to the ceramic surface and is not easily melted, so that it is conductive, and then to connect it with metal leads or other metal conductive layers by welding process to make it a whole.

[0009] How to achieve strong bonding and metallization of high thermal conductivity ceramic materials to cope with high-temperature welding and high-low temperature oscillations during long-term use has become a hot topic that urgently needs in-depth research.

[0010] Magnetron sputtering is a commonly used metallization method in the semiconductor industry. In recent years, the emerging high-power magnetron sputtering (HiPIMS) technology has been able to improve coating density and thus enhance the adhesion between the coating and the substrate by exciting high-density, high-energy, and high-ionization plasmas. Simultaneously, the high plasma energy increases the energy for the migration of deposited atoms, which can fill the voids in columnar crystal growth, resulting in a denser structure.

[0011] Due to the welding requirements of 5G dielectric filter ceramics, multi-layer structures are often needed to improve the adhesion between the coating and the metal welding layer. These multi-layer structures also reduce heat conduction to the metal-ceramic interface during welding, preventing a decrease in the bonding strength between the metal and ceramic interfaces. However, multi-layer structures often require multiple manufacturing processes, significantly increasing manufacturing costs.

[0012] To improve the film-substrate adhesion between the ceramic substrate and the surface conductive metal coating of a 5G dielectric filter, CN112779494A discloses a surface metallization process for a dielectric ceramic filter. The process includes: ultrasonically cleaning the dielectric ceramic filter using an organic solvent; high-temperature baking and heat preservation; then vacuuming and heating it in a furnace; introducing argon gas into the furnace and using a Hall ion source to sputter-clean the surface of the dielectric ceramic filter; stopping the argon gas supply and using high-energy pulsed ion implantation with a metal target to implant metal ions into the surface of the dielectric ceramic filter; using magnetron sputtering with argon gas and a reducing gas, and using a metal target to deposit a metal layer on the surface of the ion-implanted metal layer; continuing to introduce argon gas and removing the dielectric ceramic filter from the furnace after cooling.

[0013] However, the above method requires the introduction of reducing gas during the preparation process, which makes the preparation process relatively complex. Summary of the Invention

[0014] To address the problems in the prior art, this invention provides a method for preparing a metallized coating on the surface of a dielectric filter.

[0015] This invention provides a method for preparing a metallized coating on the surface of a dielectric filter, comprising the following steps:

[0016] Deposition process: A metal layer is deposited on the surface of a dielectric ceramic substrate using high-power magnetron sputtering technology. First, the peak current is increased by adjusting the frequency and pulse width of the high-power magnetron sputtering technology to obtain high-density plasma. Then, the rotation speed of the dielectric ceramic substrate is reduced and an auxiliary cathode is added behind the dielectric ceramic substrate to increase the directionality of plasma movement in order to obtain columnar crystals with different tilt angles.

[0017] As a further improvement of the present invention, during the deposition process, the angle between the dielectric ceramic substrate and the target material is maintained at 20° to 30°.

[0018] As a further improvement of the present invention, during the deposition process, the dielectric ceramic substrate is placed in an argon atmosphere, and a metal plate is placed behind the dielectric ceramic substrate as an auxiliary cathode. The size of the auxiliary cathode is larger than that of the dielectric ceramic substrate, so that the dielectric ceramic substrate cannot completely block the target and the auxiliary cathode.

[0019] As a further improvement of the present invention, the auxiliary cathode is set with a negative bias voltage of 200-500V, the vacuum degree inside the furnace is 0.05-0.3Pa, and a pulse bias voltage of 50-200V and a duty cycle of 40-90% is applied to the dielectric ceramic substrate. The target material is turned on, the HiPIMS power supply is adjusted to a frequency of 300HZ and a pulse width of 100μs, and a Cu layer is deposited on the surface of the dielectric ceramic substrate.

[0020] As a further improvement of the present invention, the ceramic substrate of the activating medium is activated before the deposition process.

[0021] As a further improvement of the present invention, activating the dielectric ceramic substrate includes: first, thoroughly cleaning the dielectric ceramic substrate with alcohol, then placing it in a drying furnace to evaporate residual alcohol and water on the surface; then placing the cleaned dielectric ceramic substrate in an argon atmosphere, at a distance of 60-150 mm from the target surface, keeping the dielectric ceramic substrate facing the target; adjusting the vacuum degree to 0.06-1 Pa by adjusting the argon flow rate; performing glow discharge cleaning for 20-60 min in a vacuum coating equipment under a bias voltage of -300 to -1000 V; after glow discharge cleaning, adjusting the bias voltage to -50 to -300 V, turning on the target, adjusting the average current of the target to 0.5-20 A, and bombarding the ceramic substrate with Cu and Ar ions at high energy for 1-20 min to activate the dielectric ceramic substrate.

[0022] As a further improvement of the present invention, after activating the dielectric ceramic substrate, the glow discharge is not turned off, so that the glow discharge is uninterrupted during the deposition process.

[0023] As a further improvement of the present invention, the inclination angle between the growth direction of the columnar crystals and the dielectric ceramic matrix is ​​20° to 30°.

[0024] As a further improvement of the present invention, in the deposition process, physical vapor deposition technology is used to sputter and deposit a film on the dielectric ceramic substrate, and vacuuming, heating, plasma cleaning, surface activation and sputtering deposition of Cu coating are performed in sequence.

[0025] The beneficial effects of this invention are: by using high-energy magnetron sputtering technology, dense columnar crystals grown at an angle are deposited on the ceramic dielectric filter, which reduces the heat transfer from the solder to the metal-ceramic interface and increases the metal-ceramic bonding force. This method only requires depositing a Cu metal layer on the surface of the dielectric ceramic, which reduces the metallization process on the surface of the dielectric ceramic, greatly reduces the production cost, and does not require the introduction of reducing gas during the preparation process, making the preparation process simpler. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other solutions can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the deposition system structure of a method for preparing a metallized coating on the surface of a dielectric filter according to the present invention.

[0028] Figure 2 This is a schematic diagram of the coating structure of a method for preparing a metallized coating on the surface of a dielectric filter according to the present invention. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0030] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] A method for preparing a metallized coating on the surface of a dielectric filter involves first increasing the peak current by adjusting the frequency and pulse width of high-power magnetron sputtering (HiPIMS) technology to obtain high-density plasma, then reducing the rotation speed of the substrate, and adding an auxiliary cathode behind the substrate to increase the directionality of plasma movement, making it easier to obtain columnar crystals with different tilt angles.

[0034] The specific process includes:

[0035] Step 1: Activate the dielectric ceramic substrate. First, thoroughly clean the dielectric ceramic substrate with alcohol, then place it in a drying oven to evaporate any residual alcohol and water on the surface. Next, place the cleaned dielectric ceramic substrate in an argon atmosphere, 60–150 mm away from the target surface, ensuring the substrate is directly facing the target. Adjust the argon flow rate to achieve a vacuum level of 0.06–1 Pa; perform glow discharge cleaning for 20–60 min in a vacuum coating equipment under a bias voltage of -300–-1000 V. After glow discharge cleaning, adjust the bias voltage to -50–-300 V, turn on the Cu target, and adjust the average target current to 0.5–20 A. High-energy bombardment of the dielectric ceramic substrate with Cu and Ar ions for 1–20 min activates the dielectric ceramic substrate.

[0036] Step 2, Deposition Process: After the dielectric ceramic substrate surface is activated, a Cu layer is deposited on the dielectric ceramic substrate surface using the HiPIMS method. The dielectric ceramic substrate is placed in an argon atmosphere. The target-substrate distance remains unchanged, and the angle between the dielectric ceramic substrate and the target is adjusted to 20-30°. A metal plate, slightly larger than the dielectric ceramic substrate, is placed 2mm-5mm behind the dielectric ceramic substrate to prevent the dielectric ceramic substrate from completely blocking the target and auxiliary cathode. The auxiliary cathode is set with a negative bias voltage of 200-500V. Under the conditions of a furnace vacuum of 0.05-0.3Pa, a pulse bias voltage of 50-200V applied to the dielectric ceramic substrate, and a duty cycle of 40-90%, the Cu target is turned on, and the HiPIMS power supply is adjusted to a frequency of 300Hz and a pulse width of 100μs. A Cu layer is deposited on the dielectric ceramic substrate surface, and the deposition thickness is adjusted according to the corresponding deposition time.

[0037] Do not turn off the glow after activating the surface; keep the process uninterrupted.

[0038] In the above steps, PVD technology is used to sputter and coat the workpiece, and the following steps are performed in sequence: vacuuming (better than 5E-4Pa), heating (200℃-500℃), plasma cleaning (using argon ions to remove the oxide layer on the workpiece surface and enhance the adhesion of the film), surface activation, and sputtering deposition of Cu coating.

[0039] PVD is an abbreviation for Physical Vapor Deposition. It is a technique that, under vacuum conditions, uses physical methods to vaporize a material source (solid or liquid) into gaseous atoms or molecules, or partially ionize them, and then deposits a thin film with specific functions onto a substrate surface through a low-pressure gas (or plasma) process. PVD is one of the major surface treatment technologies, and its main methods include vacuum evaporation, sputtering, arc plasma deposition, ion plating, and molecular beam epitaxy. The main characteristics of PVD technology include environmental improvement, no pollution, low material consumption, uniform and dense film formation, and strong adhesion to the substrate.

[0040] The sedimentation system used in the sedimentation process, such as Figure 1 As shown, it includes a target 1, a dielectric ceramic substrate 2, and an auxiliary cathode 3. The dielectric ceramic substrate 2 is located between the target 1 and the auxiliary cathode 3. The target 1 is connected to a HiPIMS power supply. The dielectric ceramic substrate 2 and the auxiliary cathode 3 are each connected to a bias power supply. The target 1 and the auxiliary cathode 3 are placed vertically, while the dielectric ceramic substrate 2 is placed at an angle of 20-30°.

[0041] Example 1:

[0042] After external alcohol cleaning and drying, the ceramic substrate is placed in front of the magnetron target, 80 mm from the target surface, so that it is directly facing the target. A vacuum is drawn to a base vacuum of 1.0 × 10⁻³ Pa, then argon gas is introduced to achieve a vacuum of 1 Pa. A pulsed bias is then applied, with parameters set to -800 V, 100 kHz / 8 μs, for glow discharge cleaning for 40 min. After glow discharge cleaning, the bias is adjusted to -300 V, while other parameters remain unchanged. The Cu target is then activated, and HiPIMS is applied to the target surface at a frequency of 1000 Hz and a pulse width of 30 μs. The target peak current is adjusted to 40 A, and the ceramic substrate is bombarded with high-energy Cu ions for 20 min to activate the ceramic substrate surface.

[0043] After the ceramic substrate surface was activated, a Cu layer was deposited on the ceramic substrate surface using the HiPIMS method: The ceramic substrate was placed in an argon atmosphere. The target-substrate distance remained unchanged, and the angle between the substrate and the target was adjusted to 20°. A metal plate, slightly larger than the ceramic substrate, was placed 5 mm behind the ceramic substrate to prevent the ceramic substrate from completely blocking the target and auxiliary cathode. The auxiliary cathode was set with a negative bias of 300V. Under the conditions of a furnace vacuum of 0.2 Pa, a pulsed bias of 50V applied to the ceramic substrate, and a duty cycle of 90%, the Cu target was turned on, and the HiPIMS power supply was adjusted to a frequency of 1000 Hz and a pulse width of 30 μs. The peak current of the target was adjusted to 40 A, and a Cu layer was deposited on the ceramic substrate surface. The deposition thickness was adjusted according to the corresponding deposition time.

[0044] Example 2:

[0045] The process parameters for external cleaning and internal substrate activation remain unchanged.

[0046] After the ceramic substrate surface was activated, a Cu layer was deposited on the ceramic substrate surface using the HiPIMS method, and the ceramic substrate was placed in an argon atmosphere. The target-substrate distance remained unchanged, and the angle between the substrate and the target was adjusted to 25°. A metal plate, slightly larger than the ceramic substrate, was placed 3 mm behind the ceramic substrate to prevent the ceramic substrate from completely blocking the target and auxiliary cathode. The auxiliary cathode was set with a negative bias voltage of 400V. Under the conditions of a furnace vacuum of 0.2 Pa, a pulsed bias voltage of 200V applied to the ceramic substrate, and a duty cycle of 90%, the Cu target was turned on, and the HiPIMS power supply was adjusted to a frequency of 200 Hz and a pulse width of 150 μs. The peak current of the target was adjusted to 40 A, and a Cu layer was deposited on the ceramic substrate surface. The deposition thickness was adjusted according to the corresponding deposition time.

[0047] Comparative Example 1:

[0048] The process parameters for external cleaning and internal substrate activation remain unchanged.

[0049] After the ceramic substrate surface is activated, a Cu layer is deposited on the ceramic substrate surface using DCMS. The ceramic substrate is placed in an argon atmosphere. With the target-substrate distance unchanged, the angle between the substrate and the target adjusted to 25°, the vacuum degree inside the furnace at 0.2 Pa, the applied pulse bias voltage to the ceramic substrate at 200 V, and the duty cycle at 90%, the Cu target is turned on, and the DCMS power supply is adjusted multiple times, with an average current of 2 A, to deposit a Cu layer on the ceramic substrate surface. The deposition thickness is adjusted according to the corresponding deposition time.

[0050] The thermal conductivity of the materials was tested using a physical performance testing system and a Fourier transform thermal analysis system. The physical performance testing system primarily measures the thermal conductivity based on the steady-state heat flow principle; the Fourier transform analysis system measures the thermal diffusivity of the composite material based on the instantaneous heat flow principle, and combines this with differential scanning calorimetry to test the specific heat of the nano-copper interface material. The thermal conductivity of the material was obtained from the thermal diffusivity, density, and specific heat. Thermal resistance was tested using a MicReD T3Ster device. This device, based on a static testing method, can acquire the transient temperature response curve of the device in real time, analyze the thermal performance of structures related to the heat transfer path of the device, and construct an equivalent thermal model of the device. A microstructure mechanical testing machine was used. This device tests the bonding force between the film layer and the substrate by soldering a metal block and the film layer together and pushing the metal block with a pusher. The above data are shown in Table 1.

[0051] Table 1. Test Results

[0052]

[0053] This invention provides a method for preparing a metallized coating on the surface of a dielectric filter. By using oblique incidence, the growth direction of the columnar crystals in the coating is artificially made at a certain angle to the substrate (e.g., ...). Figure 2 As shown in the diagram, this allows for a tighter bond between the coating and the substrate. Furthermore, the columnar crystals growing at a specific angle, with their directional lobes at an angle to the substrate, effectively block surface heat and solder from eroding the substrate. Simultaneously, the high-density, high-ionization, and high-energy plasma generated by HiPIMS also contributes to a denser coating growth, reducing the porosity between the columnar crystals caused by oblique incidence, thus compensating for the disadvantages of obliquely grown columnar crystals and amplifying their advantages.

[0054] Placing an auxiliary cathode behind the ceramic substrate can compensate for the poor conductivity and low plasma density of the ceramic substrate. During the coating process, the auxiliary cathode can attract the target plasma to the substrate direction, increasing the deposition efficiency and bombardment intensity of ceramic metallization.

[0055] Compared with existing technologies, the coating prepared by this invention has the advantage of simplicity. The preparation process does not require the introduction of other reducing gases, and the coating adhesion can be improved through the coating's structural design. In terms of preparation method, this invention incorporates an auxiliary cathode, making the three-dimensional deposition process more directional, enabling the coating to grow at better angles and with greater density.

[0056] The present invention provides a method for preparing a metallized coating on the surface of a dielectric filter, which has the following characteristics:

[0057] 1. Inclination angle 20°-30°, by tilting columnar crystals, the distance between the substrate and the surface is reduced for erosion.

[0058] 2. HiPIMS technology makes the tilted columnar crystals more compact, especially in their bonding with the substrate, reducing porosity and improving compactness and bonding strength while ensuring thermal conductivity and electrical conductivity.

[0059] 3. The auxiliary cathode increases the directionality of plasma movement, deposition efficiency, and coating quality, making it easier to obtain columnar crystals with a certain tilt angle.

[0060] The present invention provides a method for preparing a metallized coating on the surface of a dielectric filter, which can be used in the semiconductor field for preparing metallized ceramic surfaces.

[0061] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a metallized coating on the surface of a dielectric filter, characterized in that, Includes the following steps: Deposition process: A metal layer is deposited on the surface of a dielectric ceramic substrate using high-power magnetron sputtering technology. First, the peak current is increased by adjusting the frequency and pulse width of the high-power magnetron sputtering technology to obtain high-density plasma. Then, the rotation speed of the dielectric ceramic substrate is reduced and an auxiliary cathode is added behind the dielectric ceramic substrate to increase the directionality of plasma movement in order to obtain columnar crystals with different tilt angles. During the deposition process, the angle between the ceramic substrate and the target material is maintained at 20° to 30°. During the deposition process, the dielectric ceramic substrate is placed in an argon atmosphere, and a metal plate is placed behind the dielectric ceramic substrate as an auxiliary cathode. The size of the auxiliary cathode is larger than that of the dielectric ceramic substrate, so that the dielectric ceramic substrate cannot completely block the target and the auxiliary cathode. The auxiliary cathode is set with a negative bias voltage of 200-500V, the vacuum degree inside the furnace is 0.05-0.3 Pa, and a pulse bias voltage of 50-200V and a duty cycle of 40-90% is applied to the dielectric ceramic substrate. The target is turned on, the HiPIMS power supply is adjusted to a frequency of 300Hz and a pulse width of 100μs, and a Cu layer is deposited on the surface of the dielectric ceramic substrate.

2. The method for preparing a metallized coating on the surface of a dielectric filter according to claim 1, characterized in that: Before the deposition process, the ceramic substrate is activated.

3. The method for preparing a metallized coating on the surface of a dielectric filter according to claim 2, characterized in that, The activation of the dielectric ceramic substrate includes: first, thoroughly cleaning the dielectric ceramic substrate with alcohol, then placing it in a drying furnace to evaporate residual alcohol and water on the surface; then placing the cleaned dielectric ceramic substrate in an argon atmosphere, 60–150 mm away from the target surface, keeping the dielectric ceramic substrate directly facing the target; adjusting the argon flow rate to adjust the vacuum level to 0.06–1 Pa; performing glow discharge cleaning for 20–60 min in a vacuum coating equipment under a bias voltage of -300–-1000 V; after glow discharge cleaning, adjusting the bias voltage to -50–-300 V, turning on the target, adjusting the average current of the target to 0.5–20 A, and bombarding the ceramic substrate with high-energy Cu and Ar ions for 1–20 min to activate the dielectric ceramic substrate.

4. The method for preparing a metallized coating on the surface of a dielectric filter according to claim 3, characterized in that, After activating the ceramic substrate, the glow discharge is not turned off, so that the glow discharge continues uninterrupted during the deposition process.

5. The method for preparing a metallized coating on the surface of a dielectric filter according to claim 1, characterized in that: The angle between the growth direction of the columnar crystals and the dielectric ceramic matrix is ​​20° to 30°.

6. The method for preparing a metallized coating on the surface of a dielectric filter according to claim 1, characterized in that: During the deposition process, physical vapor deposition technology is used to sputter and deposit a film on the dielectric ceramic substrate, and the process involves vacuuming, heating, plasma cleaning, surface activation, and sputtering deposition of a Cu coating.

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