Ceramic cover and preparation method and application thereof

Abstract

The invention provides a ceramic cover and a preparation method and application thereof, and the ceramic cover comprises a ceramic substrate which is provided with a groove; and the wireless charging coil is embedded in the groove and is compounded with the ceramic matrix into a whole. According to the ceramic cover, the wireless charging coil can be integrated on the ceramic base body, space is saved, the requirements for miniaturization and light weight of a terminal product applying the ceramic cover are met, meanwhile, the wireless charging coil and the ceramic base body are compounded into a whole, the combination strength of the wireless charging coil and the ceramic base body is high, and undesirable phenomena such as wireless charging coil falling are not prone to occurring; and the wireless charging coil which is compounded with the ceramic substrate into a whole is used as one part of the ceramic cover to bear load, so that the mechanical property and the reliability of the ceramic cover can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of wireless charging materials, and particularly relates to a ceramic cover, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, wireless charging technology has gradually been popularized in intelligent terminal products such as mobile phones and watches. To achieve the wireless charging function, an electromagnetic induction coil (or wireless charging coil) needs to be configured inside the product. In related technologies, usually, a conductive coil is adhered to the back cover of the product, but this will increase the thickness and weight of the product and is not conducive to heat dissipation.

[0003] To achieve miniaturization and light weight of the product, integrating the wireless charging coil into structural components such as the back cover of the product is a feasible solution. However, the existing integration methods generally have problems such as weak bonding force between the wireless charging coil and structural components such as the back cover, easy detachment, and poor reliability of structural components such as the back cover integrated with the wireless charging coil, resulting in a poor practical application prospect.

[0004] Specifically, the currently common integration methods mainly include the following two: (1) Prepare a conductive paste with the material for forming the wireless charging coil (mainly metal), apply the conductive paste on structural components such as the back cover (such as a ceramic back cover), and then sinter it to form a conductive coil (wireless charging coil) on the back cover and other structural components. This can reduce the weight and occupied space of the product to a certain extent. However, on the one hand, through this coating method, the coating density of the conductive paste is low, and it is difficult for the sintered conductive coil to be densified, affecting its performance. On the other hand, the main component of the conductive paste is metal, and the coating (i.e., the conductive coil) formed by it has a weak bonding force with structural components such as the back cover, and there is a risk of coating detachment; (2) Open a groove in structural components such as the ceramic back cover, and place the wireless charging coil in the groove to achieve the purpose of saving space. However, after opening the groove in structural components such as the ceramic back cover, its local thickness decreases, the mechanical properties become worse, and the reliability decreases. Therefore, to meet the reliability of the whole machine, it is usually necessary to thicken and compensate the ceramic back cover and other structural components (i.e., increase the thickness of the structural components), which is difficult to meet the requirements of product miniaturization and light weight. Summary of the Invention

[0005] The present invention provides a ceramic cover, a preparation method thereof, and an application thereof, so as to at least solve the problems of weak bonding force between the wireless charging coil and structural components such as the back cover, easy detachment, and poor reliability of structural components such as the back cover integrated with the wireless charging coil existing in the prior art.

[0006] On the one hand, the present invention provides a ceramic cover, including: a ceramic substrate provided with a groove; a wireless charging coil embedded in the groove and integrated with the ceramic substrate as a whole.

[0007] According to an embodiment of the present invention, the ceramic cover has a composite region formed by the mutual infiltration of the ceramic matrix and the wireless charging coil.

[0008] According to an embodiment of the present invention, the thickness of the composite region is in the micron range.

[0009] According to an embodiment of the present invention, the thickness of the composite region is 5 - 30 μm.

[0010] According to an embodiment of the present invention, the ceramic matrix includes a ceramic material; the wireless charging coil includes a conductive material; the composite region includes the ceramic material in the ceramic matrix and the conductive material in the wireless charging coil.

[0011] According to an embodiment of the present invention, in the ceramic cover, the four-point bending strength at the position where the wireless charging coil is located is 600 MPa - 1000 MPa.

[0012] According to an embodiment of the present invention, the ceramic matrix includes a ceramic material, and the ceramic material includes the following components in parts by mass: 2 - 6 parts of niobium pentoxide, 0 - 30 parts of alumina powder, 64 - 98 parts of yttria-doped zirconia, and in the yttria-doped zirconia, the molar ratio of yttria to zirconia is 1% - 5%.

[0013] According to an embodiment of the present invention, the wireless charging coil includes a conductive material, and the conductive material includes the following components in parts by mass: 10 - 20 parts of titanium nitride powder, 15 - 30 parts of nickel powder, 5 - 10 parts of chromium powder, 40 - 70 parts of titanium carbide powder.

[0014] According to an embodiment of the present invention, the average particle size of the nickel powder is 0.5 μm - 3 μm; and / or, the average particle size of the chromium powder is 0.5 μm - 3 μm.

[0015] According to an embodiment of the present invention, the depth of the groove is 0.05 mm - 0.5 mm; and / or, the width of the groove is 0.15 mm - 1 mm.

[0016] According to an embodiment of the present invention, the thickness of the wireless charging coil in the depth direction of the groove is less than or equal to the depth of the groove; and / or, the thickness of the wireless charging coil in the depth direction of the groove is 0.05 mm - 0.5 mm.

[0017] According to an embodiment of the present invention, the thickness of the ceramic matrix is 0.3 mm - 0.6 mm.

[0018] According to an embodiment of the present invention, it further includes an explosion-proof film located on the side of the ceramic matrix where the groove is provided and covering the wireless charging coil.

[0019] According to an embodiment of the present invention, the explosion-proof film includes a plastic film.

[0020] On the other hand, the present invention also provides a method for preparing the above-mentioned ceramic cover, including the following steps: providing a ceramic green body for forming the ceramic matrix, the ceramic green body being reserved with a sink for forming the groove; after mixing the conductive material raw powder for forming the wireless charging coil and the second binder, injecting them into the sink and forming a coil green body to obtain a composite green body; sintering the composite green body to obtain the ceramic cover.

[0021] According to an embodiment of the present invention, the depth of the sink of the ceramic green body is 0.5 mm to 2 mm; and / or, the width of the sink of the ceramic green body is 0.2 mm to 1 mm.

[0022] According to an embodiment of the present invention, the ceramic green body is injection molded from ceramic material raw powder, and the density ratio of the ceramic green body to the ceramic material raw powder is 50% to 65%; and / or, the density ratio of the coil green body to the conductive material raw powder is 53% to 68%; and / or, the ceramic green body is injection molded from ceramic material raw powder, and the density ratio of the coil green body to the conductive material raw powder is greater than the density ratio of the ceramic green body to the ceramic material raw powder. Preferably, the difference between the density ratio of the coil green body to the conductive material raw powder and the density ratio of the ceramic green body to the ceramic material raw powder is 3% to 5%.

[0023] According to an embodiment of the present invention, the composite green body is first heated to 500 - 800 °C for debinding, and then heated to 1400 - 1550 °C for the sintering, and the sintering time is 30 min to 180 min.

[0024] On the other hand, the present invention also provides an electronic product, which includes the above-mentioned ceramic cover.

[0025] The ceramic cover, its preparation method and application provided by the present invention can integrate the wireless charging coil on the ceramic matrix, save space, meet the requirements of miniaturization and light weight of the terminal products applying the ceramic cover. At the same time, the wireless charging coil and the ceramic matrix are compounded into one body, and the combination strength between the two is strong, and it is not easy to occur adverse phenomena such as the detachment of the wireless charging coil. There is no risk of coating detachment, and the wireless charging coil compounded with the ceramic matrix as a part of the ceramic cover bears the load, which can ensure the mechanical properties and reliability of the ceramic cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the ceramic cover according to an embodiment of the present invention;

[0027] Figure 2 Cross-sectional schematic view of the position of the wireless charging coil of the ceramic cover according to an embodiment of the present invention;

[0028] Figure 3 Scanning electron microscope image of the interface between the ceramic substrate and the wireless charging coil in Embodiment 1 of the present invention.

[0029] Explanation of reference numerals: 1: Ceramic substrate; 2: Wireless charging coil; 3: Composite area. Detailed implementation manners

[0030] To enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below. The following specific implementation manners are only used to describe the principles and features of the present invention, and the examples are only used to explain the present invention, not to limit the scope of the present invention. Based on the embodiments of the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0031] An embodiment of the present invention provides a ceramic cover, as Figure 1 and Figure 2 shown, the ceramic substrate 1 includes: a ceramic substrate 1 provided with a groove; a wireless charging coil 2 embedded in the groove and integrated with the ceramic substrate 1 as a whole.

[0032] The ceramic cover provided by the embodiment of the present invention is a ceramic cover with a wireless charging function. Its wireless charging coil 2 is integrated in the groove of the ceramic substrate 1, saving space and meeting the requirements of miniaturization and light weight of the terminal products using this ceramic cover. At the same time, the wireless charging coil 2 is integrated with the ceramic substrate 1 as a whole, and the combination strength between the two is strong, and it is not easy to occur bad phenomena such as the wireless charging coil 2 falling off, and there is no risk of coating peeling off. Moreover, the wireless charging coil 2 integrated with the ceramic substrate 1 bears the load as a part of the ceramic cover, which can ensure the mechanical properties and reliability of the ceramic cover.

[0033] Specifically, in the above ceramic cover, the four-point bending strength at the position of the wireless charging coil 2 can be 600 MPa to 1000 MPa, such as 600 MPa, 650 MPa, 700 MPa, 750 MPa, 800 MPa, 850 MPa, 900 MPa, 950 MPa, 1000 MPa or any range composed of any two of them.

[0034] The ceramic cover of the embodiment of the present invention can specifically be used as an appearance structural member of terminal products such as mobile phones, tablets, and smart wearable devices (such as watches), for example, as the back cover (ceramic back cover) of these terminal products.

[0035] Specifically, the above-mentioned ceramic substrate 1 may include zirconia-based ceramics, which have the characteristics of a texture as gentle as jade, excellent wear resistance, excellent corrosion resistance, and good skin-friendly feeling, etc., and are more conducive to the application of the ceramic cover in the appearance structure parts of terminals such as mobile phones, tablets, and smart wearable devices (such as watches).

[0036] Specifically, the ceramic substrate 1 includes a ceramic material, and the ceramic material may include a ceramic main material. As the main component of the ceramic material (ceramic substrate 1), its mass percentage content (mass fraction) in the ceramic substrate 1 is usually greater than 50%. The ceramic main material may specifically include zirconia, and the formed ceramic substrate 1 is a zirconia-based ceramic.

[0037] In addition, the ceramic substrate 1 may further include ceramic dyes and / or ceramic stabilizers, etc. The ceramic dyes are used to dye the ceramic substrate 1 to make the ceramic cover present corresponding colors. Its mass percentage content in the ceramic substrate 1 can be 2% - 6%, such as 2%, 3%, 4%, 5%, 6% or the range composed of any two of them. The ceramic dyes may include black ceramic materials (black pigments), and specifically may include niobium pentoxide; the ceramic stabilizers can play roles such as stabilizing the structure of the ceramic main material, and specifically may include alumina (generally alumina powder) and / or yttrium oxide.

[0038] Generally, in the ceramic substrate 1, zirconia is in a polycrystalline structure (that is, zirconia particles are polycrystalline particles (secondary particles) aggregated by multiple primary particles), and yttrium oxide can be doped into zirconia to stabilize the crystal phase and other characteristics of zirconia, forming zirconia doped with yttrium oxide (or yttrium-stabilized zirconia). Among them, in the zirconia doped with yttrium oxide, the molar ratio of yttrium oxide to zirconia can be 1% - 5% (that is, the molar quantity of yttrium oxide accounts for 1% - 5% of the molar quantity of zirconia), such as 1%, 2%, 3%, 4%, 5% or the range composed of any two of them.

[0039] In some embodiments, the ceramic material may include the following components in parts by mass: 2 - 6 parts of niobium pentoxide, 0 - 30 parts of alumina powder, and 64 - 98 parts of zirconia doped with yttrium oxide.

[0040] Specifically, based on the total mass of the ceramic material (ceramic matrix 1) being 100 parts, niobium pentoxide is 2 to 6 parts (i.e., the mass percentage content of niobium pentoxide in the ceramic matrix 1 is 2% to 6%). For example, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, or a range composed of any two of them. The alumina powder is 0 to 30 parts (i.e., the mass percentage content of the alumina powder in the ceramic matrix 1 is 0 to 30%). For example, 0 parts (i.e., the ceramic matrix 1 does not contain alumina powder), 1 part, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, or a range composed of any two of them. Zirconia doped with yttrium oxide is 64 to 98 parts (i.e., the mass percentage content of zirconia doped with yttrium oxide in the ceramic matrix 1 is 64% to 98%). For example, 64 parts, 68 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, 98 parts, or a range composed of any two of them.

[0041] In addition, the wireless charging coil 2 includes a conductive material, which may specifically include a cermet material. The formed wireless charging coil 2 is a ring-shaped cermet coil made of cermet, and the cermet is integrated as the wireless charging coil 2 in the ceramic cover.

[0042] Specifically, the conductive material (cermet material) may include a ceramic material and a metal material. By introducing the ceramic material, the wireless charging coil 2 has a ceramic phase, which is more conducive to being compounded with the ceramic matrix 1 and improving properties such as the interfacial bonding strength between the two.

[0043] Generally, the mass percentage content of the ceramic material in the conductive material (wireless charging coil 2) may be greater than or equal to the mass percentage content of the metal material in the wireless charging coil 2.

[0044] In some embodiments, based on the total mass of the conductive material (wireless charging coil 2) being 100 parts, the ceramic material may be greater than 50 parts, specifically 50 to 90 parts (i.e., the mass percentage content of the ceramic material in the conductive material (wireless charging coil 2) is greater than 50%, specifically 50% to 90%). For example, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, or a range composed of any two of them; the metal material may be 10 to 50 parts, for example, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, or a range composed of any two of them.

[0045] Among them, the ceramic material in the wireless charging coil 2 may include titanium nitride powder and / or titanium carbide powder, which can maintain a ceramic phase in the wireless charging coil 2 while also maintaining high conductivity, facilitating the function of the wireless charging coil 2.

[0046] In some embodiments, based on 100 parts by total mass of the conductive material (wireless charging coil 2), the titanium nitride powder can be 10 to 20 parts, such as 10 parts, 13 parts, 15 parts, 18 parts, 20 parts, or a range composed of any two of them. The titanium carbide powder can be 40 to 70 parts, such as 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, or a range composed of any two of them.

[0047] In addition, the metal materials in the wireless charging coil 2 can include nickel powder and / or chromium powder.

[0048] In some embodiments, based on 100 parts by total mass of the conductive material (wireless charging coil 2), the nickel powder is 15 to 30 parts, such as 15 parts, 20 parts, 25 parts, 30 parts, or a range composed of any two of them. The chromium powder is 5 to 10 parts, such as 5 parts, 8 parts, 10 parts, or a range composed of any two of them.

[0049] In some specific embodiments, the conductive material (wireless charging coil 2) includes the following components in parts by mass: 10 to 20 parts of titanium nitride powder, 15 to 30 parts of nickel powder, 5 to 10 parts of chromium powder, and 40 to 70 parts of titanium carbide powder. Through this cermet formulation, the interfacial bonding with the ceramic substrate 1 (especially zirconia-based ceramics) can be further optimized, and the strength between the wireless charging coil 2 and the ceramic substrate 1 can be improved.

[0050] Specifically, based on 100 parts by total mass of the conductive material (wireless charging coil 2), the titanium nitride powder is 10 to 20 parts, such as 10 parts, 13 parts, 15 parts, 18 parts, 20 parts, or a range composed of any two of them. The titanium carbide powder is 40 to 70 parts, such as 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, or a range composed of any two of them. The nickel powder is 15 to 30 parts, such as 15 parts, 20 parts, 25 parts, 30 parts, or a range composed of any two of them. The chromium powder is 5 to 10 parts, such as 5 parts, 8 parts, 10 parts, or a range composed of any two of them.

[0051] In addition, the average particle size D50 of the nickel powder can be 0.5 μm to 3 μm, such as 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, or a range composed of any two of them.

[0052] In addition, the average particle size D50 of the chromium powder can be 0.5 μm to 3 μm, such as 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, or a range composed of any two of them.

[0053] Continue to refer to Figure 2, the ceramic cover has a composite region 3 formed by the mutual penetration of the ceramic substrate 1 and the wireless charging coil 2. Specifically, at the interface where the wireless charging coil 2 contacts the ceramic substrate 1, part of it penetrates into the interior of the ceramic substrate 1 to form the composite region 3. The composite region 3 includes the ceramic material in the ceramic substrate 1 and the conductive material in the wireless charging coil 2, enabling the wireless charging coil 2 and the ceramic substrate 1 to have good interfacial bonding and improving the bonding strength between the two.

[0054] Generally, the thickness of the composite region 3 (i.e., the thickness of the composite region 3 in the thickness direction of the ceramic substrate 1) is on the micron scale. The thickness of the composite region 3 can specifically be 5 - 30 μm, such as 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm, 25 μm, 28 μm, 30 μm, or any range composed of any two of them.

[0055] In addition, the depth H1 of the groove can be 0.05 mm - 0.5 mm, such as 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, or any range composed of any two of them.

[0056] In addition, the width W1 of the groove can be 0.15 mm - 1 mm, such as 0.15 mm, 0.2 mm, 0.4 mm, 0.5 mm, 0.7 mm, 0.85 mm, 1 mm, or any range composed of any two of them.

[0057] Generally, the thickness of the wireless charging coil 2 in the depth direction of the groove is less than or equal to the depth H1 of the groove.

[0058] In some embodiments, the thickness of the wireless charging coil 2 in the depth direction of the groove (i.e., the embedding depth of the wireless charging coil 2) can be 0.05 mm - 0.5 mm, such as 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, or any range composed of any two of them. The thickness of the wireless charging coil 2 in the depth direction of the groove described here does not include the thickness of the composite region 3.

[0059] Specifically, the groove on the ceramic substrate 1 has a structure adapted to the wireless charging coil 2, and its projection on the plane where the ceramic substrate 1 is located is coil-shaped, usually in a racetrack shape (as Figure 1 shown), and the annular pattern formed by its winding can specifically be circular (as Figure 1 shown) or square (not shown in the figure), and no special limitation is made on this.

[0060] In addition, the thickness of the ceramic substrate 1 can be 0.3 mm to 0.6 mm, such as 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, or the range formed by any two of them. It can be understood that the thickness (0.3 mm to 0.6 mm) of the ceramic substrate 1 described here refers to the thickness at the position where the ceramic substrate 1 is not provided with a groove.

[0061] In addition, the above-mentioned ceramic cover may further include an explosion-proof film located on the side of the ceramic substrate 1 where the groove is provided and covering the wireless charging coil 2. By providing the explosion-proof film, it is possible to prevent the ceramic cover from bursting during application and the ceramic cover material from splashing onto other structural components in the electronic product, resulting in damage to other structural components.

[0062] Specifically, the explosion-proof film includes a flexible film, and specifically may include a plastic film.

[0063] In addition, the above-mentioned ceramic cover is also provided with a connection port (or connection interface) for the wireless charging coil 2, which is used to connect the wireless charging coil 2 to the circuit in the electronic product to achieve the wireless charging function.

[0064] Specifically, the ceramic cover of the embodiment of the present invention can be obtained according to a preparation process including the following steps: providing a ceramic green body for forming the ceramic substrate 1, and the ceramic green body is reserved with a sink for forming a groove; after mixing the conductive material raw powder for forming the wireless charging coil 2 and the second binder, injecting them into the sink and forming a coil green body to obtain a composite green body; sintering the composite green body to obtain the ceramic cover.

[0065] Thus, in the embodiment of the present invention, by integrally sintering the ceramic green body and the coil green body injected into the sink of the ceramic green body, the wireless charging coil 2 and the ceramic substrate 1 are integrated together, so that the wireless charging coil 2 and the ceramic substrate 1 are tightly combined, and there is no gap between them. Specifically, the wireless charging coil 2 and the ceramic substrate 1 can penetrate each other to form a composite region 3, so that the wireless charging coil 2 and the ceramic substrate 1 form a good interfacial bond, improving the bonding strength between the two; at the same time, the wireless charging coil 2 composite with the ceramic substrate 1 as a part of the ceramic cover bears the load, ensuring the mechanical properties and reliability of the ceramic cover.

[0066] The embodiment of the present invention also provides a preparation method for the above-mentioned ceramic cover, including the following steps: providing a ceramic green body for forming the ceramic substrate 1, and the ceramic green body is reserved with a sink for forming a groove; after mixing the conductive material raw powder for forming the wireless charging coil 2 and the second binder, injecting them into the sink and forming a coil green body to obtain a composite green body; sintering the composite green body to obtain the ceramic cover.

[0067] In the embodiments of the present invention, through secondary injection molding, a composite blank formed by mutual embedding of a ceramic green body and a wireless charging coil 2 green body is formed, and then the composite blank is integrally sintered (i.e., co-sintering the ceramic green body and the coil green body), so as to integrate the wireless charging coil 2 with the ceramic matrix 1, and a ceramic cover with a wireless charging function is manufactured. Through this preparation process, the wireless charging coil 2 and the ceramic matrix 1 can penetrate into each other to form a composite region 3, so that the wireless charging coil 2 and the ceramic matrix 1 form a good interfacial bond, improving the bonding strength between the two. Compared with the existing coating or printing and other integration methods, in the embodiments of the present invention, the wireless charging coil 2 is integrated into the ceramic matrix 1 by an integral sintering method to manufacture a ceramic cover, which can avoid the phenomenon of the wireless charging coil 2 falling off, etc.; at the same time, the wireless charging coil 2 integrated with the ceramic matrix 1 as a part of the ceramic cover bears the load, ensuring the mechanical properties and reliability of the ceramic cover. Compared with the existing integration method of opening a groove in the ceramic cover and then placing the wireless charging coil 2 in the groove, in the embodiments of the present invention, the wireless charging coil 2 is integrated into the ceramic matrix 1 by an integral sintering method to manufacture a ceramic cover, without sacrificing the reliability of the ceramic matrix 1, and can avoid problems such as local thickness reduction of the ceramic cover, poor mechanical properties, low reliability, and increasing the thickness of the ceramic cover to meet the reliability of the whole machine, and thus it is difficult to balance the requirements of product miniaturization and lightweight.

[0068] Generally, during the sintering process, the ceramic green body and the coil green body in the composite blank will shrink. In the manufactured ceramic cover, the depth H1 of the groove of the ceramic matrix 1 will be less than the depth H0 of the sink of the ceramic green body, and usually 15% ≤ (H0 - H1) / H1 ≤ 20% (i.e., the shrinkage ratio is 15% - 20%), and the width W1 of the groove of the ceramic matrix 1 will be less than the width W0 of the sink of the ceramic green body, and usually 15% ≤ (W0 - W1) / W1 ≤ 20%.

[0069] In some embodiments, the depth of the sink of the ceramic green body can be 0.5 mm - 2 mm, such as 0.5 mm, 0.8 mm, 1 mm, 1.3 mm, 1.5 mm, 1.7 mm, 2 mm or the range composed of any two of them.

[0070] In some embodiments, the width of the sink of the ceramic green body can be 0.2 mm - 1 mm, such as 0.2 mm, 0.4 mm, 0.5 mm, 0.7 mm, 0.85 mm, 1 mm or the range composed of any two of them.

[0071] Specifically, the ceramic green body is injection-molded from the original ceramic powder. The preparation process of the ceramic green body may specifically include: ball-milling and mixing the original ceramic powder (such as niobium pentoxide and zirconia doped with yttrium oxide, etc.), granulating to form a uniform powder, then mixing the formed powder (or called granulated powder) with the first binder, kneading, and then injection-molding into a ceramic green body with a preset ceramic cover shape, and reserving a sunk groove in the ceramic green body. Specifically, it can be injection-molded in a mold to form a ceramic green body with a preset shape and make the ceramic green body reserve a sunk groove.

[0072] Exemplarily, the above-mentioned original ceramic powder may be a zirconia-based powder including 2 - 6 parts of niobium pentoxide, 0 - 30 parts of alumina powder, and 64 - 98 parts of zirconia doped with yttrium oxide.

[0073] Exemplarily, in the above-mentioned preparation process, the original conductive material powder used may be a cermet powder including 10 - 20 parts of titanium nitride powder, 15 - 30 parts of nickel powder, 5 - 10 parts of chromium powder, and 40 - 70 parts of titanium carbide powder.

[0074] Specifically, the first binder may include paraffin wax, and the second binder may include polyvinyl butyral.

[0075] In addition, the relative density of the ceramic green body (i.e., the ratio of the density of the ceramic green body to the density of the original ceramic powder) ρ1 may be 50% - 65%, such as 50%, 53%, 55%, 58%, 60%, 63%, 65% or the range composed of any two of them.

[0076] Among them, the density of the ceramic green body is the ratio of the weight of the ceramic green body to the volume of the ceramic green body. The volume of the ceramic green body is basically equal to the cavity volume of the mold used when injection-molding the ceramic green body. The density of the original ceramic powder can be converted according to the density of each ceramic material and its mass fraction in the original ceramic powder. For example, taking the total mass of the original ceramic powder as 100 parts, the original ceramic powder includes 2 - 6 parts of niobium pentoxide (mass fraction is 2% - 6%), 0 - 30 parts of alumina powder (mass fraction is 0 - 30%), and 64 - 98 parts of zirconia doped with yttrium oxide (mass fraction is 64% - 98%). Then the density of the original ceramic powder = density of niobium pentoxide × mass fraction of niobium pentoxide (i.e., 2% - 6%) + density of alumina powder × mass fraction of alumina powder (i.e., 0 - 30%) + density of zirconia doped with yttrium oxide × mass fraction of zirconia doped with yttrium oxide (i.e., 64% - 98%).

[0077] In addition, the relative density of the coil green body (i.e., the ratio of the density of the coil green body to the density of the original conductive material powder) ρ2 may be 53% - 68%, such as 53%, 55%, 58%, 60%, 63%, 65%, 68% or the range composed of any two of them.

[0078] Among them, the density of the coil green body is the ratio of the weight of the coil green body to the volume of the charging coil. The density of the original powder of the conductive material can be converted according to the density of each conductive material and its mass fraction in the original powder of the conductive material. For example, taking the total mass of the original powder of the conductive material as 100 parts, the original powder of the conductive material includes 10 - 20 parts of titanium nitride powder (mass fraction is 10% - 20%), 15 - 30 parts of nickel powder (mass fraction is 15% - 30%), 5 - 10 parts of chromium powder (mass fraction is 5% - 10%), and 40 - 70 parts of titanium carbide powder (mass fraction is 40% - 70%). Then the density of the original powder of the conductive material = density of titanium nitride powder × mass fraction of titanium nitride powder (i.e., 10% - 20%) + density of nickel powder × mass fraction of nickel powder (i.e., 15% - 30%) + density of chromium powder × mass fraction of chromium powder (i.e., 5% - 10%) + density of titanium carbide powder × mass fraction of titanium carbide powder (i.e., 40% - 70%).

[0079] Specifically, the relative density ρ2 of the coil green body is greater than the relative density ρ1 of the ceramic green body. Preferably, the difference between the relative density ρ2 of the charging coil and the relative density ρ1 of the ceramic green body is 3% - 5%, such as 3%, 3.5%, 4%, 4.5%, 5% or the range composed of any two of them.

[0080] By controlling the relative density ρ1 of the ceramic green body, the relative density ρ2 of the coil green body, and the difference between the two within the above range, matching the shrinkage ratios of the two ceramics, and controlling the stress mismatch between the ceramic matrix 1 and the wireless charging coil 2 (cermet), the performance of the obtained ceramic cover is further improved.

[0081] In addition, during the above preparation process, the sintering temperature can be 1400 - 1550 °C, such as 1400 °C, 1430 °C, 1450 °C, 1480 °C, 1500 °C, 1530 °C, 1550 °C or the range composed of any two of them, and the sintering time can be 30 min - 180 min, such as 30 min, 50 min, 60 min, 80 min, 100 min, 120 min, 150 min, 180 min or the range composed of any two of them. Through this sintering process, it is beneficial to achieve a good combination between the ceramic matrix 1 and the wireless charging coil 2.

[0082] Generally, the composite green body can be first heated to 500 - 800 °C (degumming temperature) for degumming (or debinding, that is, burning off gum-like materials such as the first binder and the second binder through high-temperature treatment), and then heated to the above sintering temperature (1400 - 1550 °C) for sintering. Among them, the degumming temperature is, for example, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C, 800 °C or the range composed of any two of them.

[0083] In some embodiments, the debinding process may include: heating the composite green body to a first temperature and then to the debinding temperature (hereinafter referred to as the second temperature), and holding at the second temperature for a preset time to perform debinding on the composite green body.

[0084] Among them, the composite green body can be heated from room temperature to the first temperature, and the first temperature can be 150 - 300 °C, such as 150 °C, 180 °C, 200 °C, 230 °C, 250 °C, 280 °C, 300 °C or the range composed of any two of them.

[0085] In addition, the difference between the second temperature and the first temperature can be 200 - 500 °C, such as 200 °C, 230 °C, 250 °C, 280 °C, 300 °C, 330 °C, 350 °C, 380 °C, 400 °C, 430 °C, 450 °C, 480 °C, 500 °C or the range composed of any two of them.

[0086] In addition, during the process of heating the composite green body to the first temperature and from the first temperature to the second temperature, the heating rate can be 1 - 10 °C / min, such as 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 8 °C / min, 10 °C / min or the range composed of any two of them.

[0087] Specifically, the holding time at the second temperature can be 20 - 70 min, such as 20 min, 30 min, 40 min, 50 min, 60 min, 70 min or the range composed of any two of them.

[0088] In some embodiments, the sintering process may include: heating the debound composite green body to a third temperature (specifically, heating the composite green body from the second temperature to the third temperature), holding at the third temperature for a preset time, then heating to a fourth temperature, holding at the fourth temperature for a preset time, and then heating to the sintering temperature (hereinafter referred to as the fifth temperature), and holding at the fifth temperature for a preset time (i.e., the above-mentioned sintering time) to sinter the composite green body.

[0089] Among them, the third temperature can be 900 - 1050 °C, such as 900 °C, 930 °C, 950 °C, 980 °C, 1000 °C, 1030 °C, 1050 °C or the range composed of any two of them, and the fourth temperature can be 1100 - 1300 °C, such as 1100 °C, 1130 °C, 1150 °C, 1180 °C, 1200 °C, 1230 °C, 1250 °C, 1280 °C, 1300 °C or the range composed of any two of them.

[0090] In addition, the holding time at the third temperature can be 20 to 50 min, such as 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, or the range composed of any two of them.

[0091] In addition, the difference between the third temperature and the second temperature can be 400 to 550 °C, such as 400 °C, 430 °C, 450 °C, 480 °C, 500 °C, 530 °C, 550 °C, or the range composed of any two of them; the difference between the fourth temperature and the third temperature can be 100 to 300 °C, such as 100 °C, 130 °C, 150 °C, 180 °C, 200 °C, 230 °C, 250 °C, 280 °C, 300 °C, or the range composed of any two of them; the difference between the fifth temperature and the fourth temperature can be 150 to 450 °C, such as 150 °C, 180 °C, 200 °C, 230 °C, 250 °C, 280 °C, 300 °C, 330 °C, 350 °C, 380 °C, 400 °C, 430 °C, 450 °C, or the range composed of any two of them.

[0092] In addition, the holding time at the fourth temperature can be 20 to 50 min, such as 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, or the range composed of any two of them.

[0093] In addition, during the process of heating the debound composite green body to the third temperature, from the third temperature to the fourth temperature, and from the fourth temperature to the fifth temperature, the heating rate can be 2 to 5 °C / min, such as 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, or the range composed of any two of them.

[0094] In the above preparation process, after sintering is completed, the sintered body can be gradually cooled. Specifically, it can be first cooled to the sixth temperature, then cooled to the seventh temperature, and then cooled to room temperature, thus obtaining the ceramic cover.

[0095] Among them, during the process of cooling to the sixth temperature and from the sixth temperature to the seventh temperature, the cooling rate can be 1 to 10 °C / min, such as 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 7 °C / min, 9 °C / min, 10 °C / min, or the range composed of any two of them.

[0096] According to the research of the inventors, through the above debinding and sintering processes, by holding at different temperature regions, the phenomena such as cracks caused by ceramic stress can be overcome, and the performance of the obtained ceramic cover can be further improved. At the same time, different reactions occur in different temperature regions, which is also a factor in enhancing the performance of the ceramic cover.

[0097] In specific implementation, raw materials such as titanium nitride powder, nickel powder, chromium powder, and titanium carbide powder can be ball-milled and mixed, granulated to form a uniform powder. Then, the formed powder is mixed with a second binder, ball-milled, and kneaded, and then injection-molded into the sink of the ceramic green body. Next, the obtained composite green body is degummed (specifically, negative pressure degreasing can be carried out), and then sintered (specifically, vacuum sintering can be carried out) to obtain a ceramic cover (ceramic sintered body). During application, the ceramic cover can be processed and polished by CNC machining to make it a ceramic cover product for end products, such as a ceramic back cover for smart terminals such as mobile phones, tablets, and smart wearable devices (such as watches), specifically a ceramic battery cover. The embodiments of the present invention are also applicable to other devices such as antennas and NFC, realizing the integration of antennas, NFC and other devices on the ceramic back cover.

[0098] An embodiment of the present invention further provides an electronic product, which includes the above-mentioned ceramic cover. The above-mentioned ceramic cover can specifically be used as the ceramic back cover of the electronic product, and the wireless charging coil 2 is located on the inner side surface of the ceramic cover (that is, the surface of the ceramic cover facing the inside of the electronic product). Exemplarily, the electronic product can be a smart terminal such as a mobile phone, a tablet, or a smart wearable device (such as a watch).

[0099] The present invention will be further introduced through specific embodiments below.

[0100] Embodiment 1

[0101] The ceramic cover provided in this Embodiment 1 includes a ceramic substrate 1 and a wireless charging coil 2. The ceramic substrate 1 has a groove, and the wireless charging coil 2 is arranged in the groove and is integrated with the ceramic substrate 1. The thickness of the wireless charging coil 2 in the depth direction of the groove is the same as the groove depth (the depth of the groove). The thickness of the ceramic substrate 1 is 0.4 mm, the embedding depth of the wireless charging coil 2 is 0.2 mm, and the width is 0.34 mm. The wireless charging coil 2 and the ceramic substrate 1 penetrate each other to form a composite region 3. Among them, the thickness of the composite region 3 is 12 μm, and the microscopic morphology diagram is as Figure 3 shown. The four-point bending strength at the position of the wireless charging coil 2 of the ceramic cover is 800 MPa.

[0102] The preparation process of the ceramic cover in this Embodiment 1 is specifically as follows:

[0103] 0.3 kg of niobium pentoxide powder and 9.7 kg of yttrium-stabilized zirconia powder (the molar ratio of yttrium oxide to zirconia is 3%) are ball-milled and mixed, granulated to form a uniform granulated powder; the granulated powder and 1.5 kg of paraffin are kneaded and injection-molded into a ceramic green body (zirconia green body) with a preset shape, and a racetrack-shaped coil sink is reserved in the ceramic green body (the same as Figure 1The wireless charging coil structures are the same); among them, the relative density ρ1 of the ceramic green body is 56% (by weighing the weight of the ceramic green body and calculating the ratio of the weight of the ceramic green body to the volume of the die cavity (which is also the volume of the ceramic green body), the density of the ceramic green body is obtained, and then its relative density ρ1 is calculated). The depth of the sinking groove is 1 mm, and the width of the sinking groove is 0.5 mm;

[0104] 1.5 kg of titanium nitride powder, 2 kg of nickel powder, 0.5 kg of chromium powder, and 6 kg of titanium carbide powder are ball-milled, mixed, and granulated to form a uniform powder. The formed powder and 1.3 kg of polyvinyl butyral are kneaded and injection-molded into the runway-shaped coil sinking groove of the ceramic green body to form a coil green body in the sinking groove (the relative density ρ2 of the coil green body is 60% (by weighing the increased weight of the composite green body (i.e., the weight of the coil green body) and calculating the ratio of the volume of the charging coil green body to the volume of the coil green body, the density of the coil green body is obtained, and then its relative density ρ2 is calculated)), and a composite green body is obtained; among them, the average particle size of the nickel powder is 1.0 μm, and the average particle size of the chromium powder is 1.0 μm.

[0105] The composite green body is placed in a kiln for debinding and sintering. The sintering procedure is shown in Table 1; among them, after sintering, the sintered cover body is polished, and connection interfaces are welded to both ends of the wireless charging coil to obtain a ceramic cover with a wireless charging coil. Among them, the thickness of the ceramic matrix is 0.4 mm, and the thickness of the wireless charging coil in the depth direction of the groove (i.e., the metal-ceramic embedding depth) is 0.2 mm.

[0106] Table 1 Exhaust gas and sintering temperature procedures in the process of preparing the ceramic cover by integral sintering in Example 1

[0107]

[0108] In Table 1, a It indicates that this process section is a heat preservation process. Taking process section 3 as an example, it means heat preservation at 500 °C for 60 min; the remaining process sections are heating or cooling processes. Taking process section 2 as an example, it means the process of heating from 200 °C to 500 °C (i.e., setting the temperature to 500 °C to make the temperature rise from 200 °C to 500 °C), and the time of this process is 30 min; the same below, no more details will be described.

[0109] Comparative Example 1

[0110] The difference between Comparative Example 1 and Example 1 is that the groove of the ceramic matrix 1 in Comparative Example 1 is not filled with a wireless charging coil 2 (that is, the ceramic cover in Comparative Example 1 only includes the ceramic matrix 1, the ceramic matrix 1 has a groove, and the conditions such as the groove depth and width are the same as those in Example 1, and the groove is not filled with the wireless charging coil 2). The thickness of the ceramic cover 1 is 0.4 mm, and the four-point bending strength at the same position as the position of the wireless charging coil 2 in Example 1 (that is, the position where the groove of the ceramic cover in Comparative Example 1 is located) of the ceramic cover in Comparative Example 1 is 300 MPa.

[0111] The difference in the preparation process of the ceramic cover in this Comparative Example 1 from that in Example 1 is only that: the cermet raw powder is not filled in the ceramic green body, that is, the wireless charging coil 2 is not formed.

[0112] It can be seen from Example 1 and Comparative Example 1 that in the ceramic cover of Example 1, the wireless charging coil 2, as a part of the ceramic cover, bears the load, which can improve the mechanical properties and reliability of the ceramic cover.

[0113] Example 2

[0114] The ceramic cover provided in this Example 2 includes a ceramic matrix 1 and a wireless charging coil 2. The ceramic matrix 1 has a groove, and the wireless charging coil 2 is arranged in the groove and is integrated with the ceramic matrix 1. The thickness of the wireless charging coil 2 in the depth direction of the groove is the same as the groove depth. The thickness of the ceramic matrix 1 is 0.4 mm, the embedding depth of the wireless charging coil 2 is 0.2 mm, and the width is 0.35 mm. The wireless charging coil 2 and the ceramic matrix 1 penetrate each other to form a composite zone 3, wherein the thickness of the composite zone 3 is 9 μm; the four-point bending strength at the position of the wireless charging coil 2 of the ceramic cover is 740 MPa.

[0115] The difference in the preparation process of the ceramic cover in this Example 2 from that in Example 1 is that the conditions during debinding and sintering are different, as specifically shown in Table 2. Except for the differences shown in Table 2, the other conditions are the same as those in Example 1.

[0116] Table 2 Debinding and sintering temperature procedures in the process of preparing the ceramic cover by integral sintering in Example 2

[0117]

[0118] In this Example 2, while improving the interfacial bonding strength between the ceramic matrix 1 and the wireless charging coil 2, the overall sintering time can also be reduced, and the cost can be reduced.

[0119] Comparative Example 2

[0120] The difference between Comparative Example 2 and Example 2 is that the groove of the ceramic substrate 1 in Comparative Example 2 is not filled with the wireless charging coil 2 (that is, the ceramic cover of Comparative Example 2 only includes the ceramic substrate 1, the ceramic substrate 1 has a groove, the conditions such as the groove depth and width are the same as those in Example 2, and the groove is not filled with the wireless charging coil 2). The thickness of the ceramic cover 1 can be 0.4 mm. The four-point bending strength at the same position as the position where the wireless charging coil 2 is located in Example 2 (that is, the position where the groove of the ceramic cover of Comparative Example 1 is located) of the ceramic cover of Comparative Example 2 is 250 MPa.

[0121] The difference in the preparation process of the ceramic cover of this Comparative Example 2 from that of Example 2 is only that: the cermet raw powder is not filled in the ceramic green body, that is, the wireless charging coil 2 is not formed.

[0122] It can be seen from Example 2 and Comparative Example 2 that in the ceramic cover of Example 2, the wireless charging coil 2, as a part of the ceramic cover, bears the load, which can improve the mechanical properties and reliability of the ceramic cover.

[0123] Example 3

[0124] The ceramic cover provided in this Example 3 includes a ceramic substrate 1 and a wireless charging coil 2. The ceramic substrate 1 has a groove, and the wireless charging coil 2 is arranged in the groove and is integrated with the ceramic substrate 1. The thickness of the wireless charging coil 2 in the groove depth direction is the same as the groove depth. The thickness of the ceramic substrate 1 is 0.4 mm, the embedding depth of the wireless charging coil 2 is 0.2 mm, and the width is 0.35 mm. The wireless charging coil 2 and the ceramic substrate 1 penetrate each other to form a composite zone 3, wherein the thickness of the composite zone 3 is 15 μm; the four-point bending strength at the position where the wireless charging coil 2 of the ceramic cover is located is 850 MPa.

[0125] The difference in the preparation process of the ceramic cover of this Example 3 from that of Example 1 is that the formulations of the ceramic green body and the coil green body are different, and the other conditions are the same as those in Example 1; the specific formulation of this Example 3 is as follows:

[0126] 0.4 kg of niobium pentoxide powder and 9.6 kg of yttria-stabilized zirconia powder (the molar ratio of yttria to zirconia is 4%) are ball-milled and mixed, granulated to form a uniform granulated powder; the granulated powder and 1.8 kg of paraffin are kneaded and injection-molded into a ceramic green body (zirconia green body) with a preset shape, and a racetrack-shaped coil sink (consistent with the Figure 1 wireless charging coil structure therein) is reserved in the ceramic green body, and the relative density ρ1 of the ceramic green body is 52%;

[0127] Mix 1 kg of titanium nitride powder, 2.5 kg of nickel powder, 1 kg of chromium powder, and 5.5 kg of titanium carbide powder by ball milling, granulate to form a uniform powder, and knead and inject the required powder and 1.2 kg of paraffin into the runway-shaped coil sink of the ceramic green body to form a coil green body in the early stage (the relative density ρ2 of the coil green body is 55%), and obtain a composite green body;

[0128] Manufacture a ceramic cover according to the processes such as debinding and sintering in Example 1.

[0129] Example 4

[0130] The ceramic cover provided in this Example 4 includes a ceramic substrate 1 and a wireless charging coil 2. The ceramic substrate 1 has a groove, and the wireless charging coil 2 is arranged in the groove and integrated with the ceramic substrate 1. The thickness of the wireless charging coil 2 in the depth direction of the groove is the same as the groove depth. The thickness of the ceramic substrate 1 is 0.4 mm, the embedding depth of the wireless charging coil 2 is 0.1 mm, and the width is 0.30 mm. The wireless charging coil 2 and the ceramic substrate 1 penetrate each other to form a composite region 3. Among them, the thickness of the composite region 3 is 8 μm; the four-point bending strength at the position of the wireless charging coil 2 of the ceramic cover is 950 MPa.

[0131] The difference between the preparation process of the ceramic cover in this Example 4 and the preparation process in Example 1 is that by modifying the mold, the width and depth of the sink of the injection-molded ceramic green body are reduced, and the other conditions are the same as those in Example 1. Manufacture a ceramic cover according to the processes such as debinding and sintering in Example 1.

[0132] In Examples 1 to 4, by balancing conditions such as the green body density, sintering temperature, sintering atmosphere, and shrinkage rate of the cermet and zirconia-based ceramics, a ceramic cover product with a wireless charging function was prepared by integral sintering, realizing a good interfacial bond between the cermet and the zirconia ceramic. Thus, the embodiments of the present invention can integrate the wireless charging coil into the ceramic cover without reducing the reliability of the ceramic back cover, achieve a good interfacial bond between the wireless charging coil and the ceramic substrate, and at the same time can save the space occupied by the wireless charging coil, meeting the requirements of product miniaturization and lightweight.

[0133] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A ceramic cover, characterized in that, Comprising: A ceramic substrate provided with a groove; A wireless charging coil embedded in the groove and integrated with the ceramic substrate.

2. The ceramic cover according to claim 1, characterized in that, The ceramic cover has a composite region formed by the mutual penetration of the ceramic substrate and the wireless charging coil.

3. The ceramic cover according to claim 2, characterized in that, The thickness of the composite region is in the micron range.

4. The ceramic cover according to claim 3, characterized in that, The thickness of the composite region is 5 - 30 μm.

5. The ceramic cover according to any one of claims 2 - 4, characterized in that, The ceramic substrate comprises a ceramic material; The wireless charging coil comprises a conductive material; The composite region comprises the ceramic material in the ceramic substrate and the conductive material in the wireless charging coil.

6. The ceramic cover according to any one of claims 1 - 4, characterized in that, In the ceramic cover, the four-point bending strength at the position where the wireless charging coil is located is 600 MPa - 1000 MPa.

7. The ceramic cover according to any one of claims 1 - 4, characterized in that, The ceramic substrate comprises a ceramic material, and the ceramic material comprises the following components in parts by mass: 2 - 6 parts of niobium pentoxide, 0 - 30 parts of alumina powder, 64 - 98 parts of yttria-doped zirconia, and in the yttria-doped zirconia, the molar ratio of yttria to zirconia is 1% - 5%.

8. The ceramic cover according to any one of claims 1 - 4, characterized in that, The wireless charging coil comprises a conductive material, and the conductive material comprises the following components in parts by mass: 10 - 20 parts of titanium nitride powder, 15 - 30 parts of nickel powder, 5 - 10 parts of chromium powder, 40 - 70 parts of titanium carbide powder.

9. The ceramic cover according to claim 8, characterized in that, The average particle size of the nickel powder is 0.5 μm - 3 μm; And / or, the average particle size of the chromium powder is 0.5 μm - 3 μm.

10. The ceramic cover according to any one of claims 1 - 4, characterized in that, The depth of the groove is 0.05 mm - 0.5 mm; And / or, the width of the groove is 0.15 mm - 1 mm.

11. The ceramic cover according to any one of claims 1 - 4, characterized in that, The thickness of the wireless charging coil in the depth direction of the groove is less than or equal to the depth of the groove; And / or, the thickness of the wireless charging coil in the depth direction of the groove is 0.05 mm - 0.5 mm.

12. The ceramic cover according to any one of claims 1 - 4, characterized in that, The thickness of the ceramic substrate is 0.3 mm - 0.6 mm.

13. The ceramic cover according to any one of claims 1 - 4, characterized in that, It further comprises an explosion-proof film located on the side of the ceramic substrate where the groove is provided and covering the wireless charging coil.

14. The ceramic cover according to claim 13, characterized in that, The explosion-proof film comprises a plastic film.

15. A method for preparing the ceramic cover according to any one of claims 1 - 14, characterized in that, Including the following steps: Providing a ceramic green body for forming the ceramic substrate, and the ceramic green body is reserved with a sink for forming the groove; After mixing the conductive material raw powder for forming the wireless charging coil and a second binder, injecting them into the sink and forming a coil green body to obtain a composite green body; Sintering the composite green body to obtain the ceramic cover.

16. The preparation method of the ceramic cover according to claim 15, characterized in that, The depth of the sink of the ceramic green body is 0.5 mm - 2 mm; And / or, the width of the sink of the ceramic green body is 0.2 mm - 1 mm.

17. The preparation method of the ceramic cover according to claim 15, characterized in that, The ceramic green body is injection-molded from ceramic material raw powder, and the density ratio of the ceramic green body to the ceramic material raw powder is 50% - 65%; And / or, the density ratio of the coil green body to the conductive material raw powder is 53% - 68%; And / or, the ceramic green body is injection-molded from ceramic material raw powder, the density ratio of the coil green body to the conductive material raw powder is greater than the density ratio of the ceramic green body to the ceramic material raw powder, and preferably the difference between the density ratio of the coil green body to the conductive material raw powder and the density ratio of the ceramic green body to the ceramic material raw powder is 3% - 5%.

18. The preparation method of the ceramic cover according to claim 15, characterized in that, The composite green body is first heated to 500-800 °C for debinding, and then heated to 1400-1550 °C for the sintering, and the sintering time is 30 min-180 min.

19. An electronic product, characterized in that, It includes the ceramic cover according to any one of claims 1-14.

Images