CN110733098A

CN110733098A - 3D ceramic shell, preparation method thereof and electronic equipment

Info

Publication number: CN110733098A
Application number: CN201910950551.7A
Authority: CN
Inventors: 罗思杰
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2019-10-08
Filing date: 2019-10-08
Publication date: 2020-01-31
Anticipated expiration: 2039-10-08
Also published as: CN110733098B

Abstract

The method for manufacturing the 3D ceramic shell comprises the steps of placing an unsintered ceramic wafer into a mold for sintering treatment to obtain the 3D ceramic shell, wherein the difference between the shrinkage rate of the ceramic wafer and the shrinkage rate of the mold is smaller than or equal to 3%, therefore, in the sintering treatment process, the ceramic wafer and the mold shrink, the shrinkage rates of the ceramic wafer and the mold are close (the difference is smaller than or equal to 3%), the ceramic wafer and the mold are well attached in the sintering process, namely the ceramic wafer and the mold are closely attached, the 3D ceramic shell with a small dimensional tolerance can be obtained, in addition, the ceramic shell is formed only through times of sintering, the strength of the ceramic shell can be effectively improved, in addition, the preparation process is simple and easy to operate, the process flows of mechanical processing such as CNC treatment and grinding wheel polishing can be omitted, and the processing difficulty of the ceramic shell is greatly reduced.

Description

3D ceramic shell, preparation method thereof and electronic equipment

Technical Field

The application relates to the technical field of electronics, in particular to a 3D ceramic shell, a preparation method thereof and electronic equipment.

Background

At present, compared with a glass shell, the ceramic shell has higher hardness, scratches are not easily generated after the ceramic shell is rubbed with a hard object, and the color, the matte, the sand blasting, the texture and the like of the ceramic shell have texture and experience which are not -like with the glass shell, but the ceramic shell is difficult to process and has high processing cost.

Therefore, research on the ceramic case is awaited.

Disclosure of Invention

, which is intended to solve technical problems of the related art at least at a fixed distance of , is a object of the present application to propose a method for manufacturing kinds of 3D ceramic cases, in which machining is not required or the manufactured 3D ceramic cases have superior strength.

According to aspects of the application, the application provides methods for manufacturing 3D ceramic shells, the method for manufacturing the 3D ceramic shells comprises the step of placing ceramic plates which are not sintered in a mold for sintering treatment to obtain the 3D ceramic shells, wherein the difference between the shrinkage rate of the ceramic plates and the shrinkage rate of the mold is less than or equal to 3% (for example, the difference is 3%, 2.5%, 2%, 1.5%, 1.0%, 0.5% and 0.1%), therefore, in the sintering treatment process, the ceramic plates and the mold shrink, the shrinkage rates of the ceramic plates and the mold are close (the difference is less than or equal to 3%), in the sintering process, the ceramic plates and the mold are well attached, namely the ceramic plates and the mold are tightly attached, the 3D ceramic shells with small size tolerance can be obtained, the ceramic shells only need to be sintered and formed for times, the ceramic shells cannot be reduced due to multiple times of sintering, the strength of the ceramic shells is effectively improved, in addition, the preparation process is simple and easy to operate, CNC processing and grinding wheels and the machining efficiency and the ceramic shells are greatly reduced.

According to another aspects of the present application, kinds of 3D ceramic shells are provided, according to the embodiment of the present application, the 3D ceramic shells are manufactured by the method for manufacturing the 3D ceramic shells, so that the ceramic shells have better strength, lower processing difficulty, higher production yield and higher dimensional accuracy.

According to an embodiment of the electronic device, the electronic device comprises the 3D ceramic shell, a display screen assembly and a main board, wherein the display screen assembly is connected with the 3D ceramic shell, an installation space is defined between the display screen assembly and the 3D ceramic shell, and the main board is arranged in the installation space and is electrically connected with the display screen assembly.

Drawings

Fig. 1 is a schematic structural diagram of the preparation of 3D ceramic shells according to examples of the present application.

Fig. 2 is a schematic structural diagram of an electronic device according to another embodiment of the present application.

Detailed Description

Embodiments of the present application are described in detail below. The following description of the embodiments is merely exemplary in nature and is in no way intended to limit the present disclosure. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

According to embodiments of the present disclosure, a method for manufacturing a 3D ceramic housing (which may be referred to as a ceramic housing for short herein) includes placing an unsintered ceramic wafer 10 in a mold 20 for sintering to obtain the 3D ceramic housing 30 (see fig. 1), wherein a difference between a shrinkage rate of the ceramic wafer and a shrinkage rate of the mold is less than or equal to 3% (e.g., the difference is 3%, 2.5%, 2%, 1.5%, 1.0%, 0.5%, 0.1%), so that the ceramic wafer and the mold shrink during the sintering process, and the shrinkage rates of the ceramic wafer and the mold are close (the difference is less than or equal to 3%), the ceramic wafer and the mold are well attached during the sintering process, i.e., the ceramic wafer and the mold are closely attached to each other, the 3D ceramic housing with a small dimensional tolerance can be obtained, if the difference between the ceramic wafer and the mold is greater than 3%, cracking during the sintering process is likely to occur, the dimensional tolerance of the obtained ceramic housing is large, the ceramic housing can be manufactured only by a CNC machining process, and the ceramic housing can be manufactured by a simple process, so that the ceramic housing manufacturing yield can be reduced, and the ceramic housing manufacturing efficiency can be greatly reduced by a simple CNC machining process, and the ceramic housing can be manufactured.

The shrinkage rate of the ceramic wafer is the percentage of the difference between the size of the ceramic wafer before sintering (before R) and the size of the ceramic wafer after sintering and cooling to room temperature (after R), i.e., the shrinkage rate is [ (pre-R-post)/pre-R ] × 100%, where the size R is the length of a certain straight line of the ceramic wafer, such as the long side or the short side of the ceramic wafer, (pre-R-post) is the length change of the same straight line before and after sintering, the calculation method of the shrinkage rate of the mold is the same as the calculation method of the shrinkage rate of the ceramic wafer, and no description is repeated here.

The inventor finds that if the ceramic wafer is placed in a shaped die (the die is shaped by sintering, and shrinkage does not occur during sintering of the ceramic wafer), the ceramic wafer is difficult to shrink due to the shaped die, so that the prepared ceramic shell is poor in compactness and easy to crack, the strength of the ceramic shell is seriously influenced, the bonding effect between the ceramic wafer and the die is poor during sintering, the size of the ceramic shell is uncontrollable, and the precision is poor, and the inventor finds that the ceramic shell is prepared by sintering twice or more times, the strength of the ceramic is reduced due to the fact that the ceramic formed by sintering is heated to the softening temperature again, the energy consumption is high, and the strength and the size precision of the ceramic shell can be effectively improved due to the fact that the ceramic wafer and the die shrink during sintering only by sintering times.

, referring to fig. 1, the mold 20 includes a female mold 22 and a male mold 21, where a shrinkage rate of the male mold 21 is greater than a shrinkage rate of the ceramic sheet 10, and a shrinkage rate of the female mold 22 is less than a shrinkage rate of the ceramic sheet 10, thereby preventing the ceramic sheet from being cracked during sintering, and where a shrinkage rate of the female mold is greater than a shrinkage rate of the ceramic sheet (i.e., the female mold shrinks faster than the ceramic sheet), the ceramic sheet is easily crushed by the female mold, and where a shrinkage rate of the male mold is less than a shrinkage rate of the ceramic sheet (i.e., the male mold shrinks slower than the ceramic sheet), thereby causing the ceramic sheet to be cracked, before and after sintering, the shrinkage rate of the ceramic sheet is 8% to 23%, such as 8%, 10%, 12%, 16%, 18%, 20%, and the mold shrinks less than 3%, such that a difference between shrinkage rates of the ceramic sheet and the mold shrinks less than a predetermined shrinkage rate, such that a difference between shrinkage rates of the ceramic sheet and the shrinkage rate of the ceramic sheet is less than a predetermined shrinkage rate of the ceramic sheet during sintering, such that a difference between shrinkage rate of the ceramic sheet and a difference of the shrinkage rate of the ceramic sheet is less than a predetermined shrinkage rate of the ceramic sheet during sintering.

, the ceramic plate is obtained by a casting process, therefore, by adopting the casting process, the continuity of the 3D ceramic shell production is enhanced, the production speed is high, the automation degree is high, the efficiency is high, the large-scale production is convenient, and the obtained 3D ceramic shell has uniform tissue structure and good product quality.

, after the ceramic plate is obtained by the casting process, the size of the ceramic plate can be calculated according to the size and shrinkage of the required ceramic shell, and then the ceramic plate with the required size is obtained by cutting.

The thickness of the ceramic sheet is 0.3-1.3 mm, such as 0.3 mm, 0.5mm, 0.7 mm, 0.9 mm, 1.1 mm or 1.3 mm. Therefore, the ceramic shell with a small thickness can be obtained, the light and thin design of the ceramic shell is facilitated, and the good impact resistance and other strength of the ceramic shell can be ensured.

, the casting slurry comprises, in mass percent, 40% to 80% (such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%) of ceramic powder, the balance being binder solution, the mass percent of binder in the binder solution being 3% to 10% (such as 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%), based on the total mass of the casting slurry forming the ceramic sheet.

Wherein, the th adhesive can be at least selected from PMMA (polymethyl methacrylate), PVA (polyvinyl alcohol) and PVB (polyvinyl butyral), and the ceramic powder can be at least selected from zirconia, alumina, silica and titania.

, the mold powder comprises, in mass percent, 90% to 97% (e.g., 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%) of mold powder, the balance being a second binder solution having a second binder content of 3% to 10% (e.g., 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%), based on the total mass of the mold powder forming the mold.

Wherein, the second binder can be at least selected from PMMA (polymethyl methacrylate), PVA (polyvinyl alcohol) and PVB (polyvinyl butyral), the die powder can be at least materials selected from zirconia, alumina, silica, titania, alumina and stainless steel, and the material of the die powder can be selected from to no to the material of the ceramic powder.

Thus, a feature defined as "", "second" may or may not include or more of that feature.

, the die is made by dry pressing die powder, the pressure of the dry pressing die is 100-200 MPa, such as 100MPa, 110MPa, 120MPa, 130MPa, 140MPa, 150MPa, 160MPa, 170MPa, 180MPa, 190MPa and 200MPa, therefore, the die with better strength and stable performance can be obtained under the pressure, if the pressure is smaller, the die powder is not tightly pressed and cracks are easy to appear in subsequent use, if the pressure is larger, the shrinkage rate of the die is easy to be smaller and the pressed blank of the die is easy to be cracked, and the die is directly obtained after the dry pressing, the die does not need to be sintered and shaped, but is sintered and formed with the ceramic plate , further the preparation process of the die is saved, namely the preparation process flow of the ceramic shell is saved.

, the sintering temperature is 1200-1500 ℃ (such as 1200 ℃, 1250 ℃, 1300 ℃, 1350 ℃, 1400 ℃, 1450 ℃ or 1500 ℃) for 2-6 hours (such as 2 hours, 3 hours, 4 hours, 5 hours or 6 hours), therefore, under the sintering condition, the prepared ceramic shell has better strength, and the shrinkage of the ceramic sheet is relative to that of the mold in the sintering process, so that the bonding condition between the ceramic sheet and the mold can be better improved, the ceramic shell with the size closer to the required size can be obtained, and the ceramic shell with more accurate size can be obtained.

In the sintering process, the pressure of the punch on the ceramic wafer is 0.1-2 MPa (such as 0.1MPa, 0.3MPa, 0.5MPa, 0.7MPa, 0.9MPa, 1MPa, 1.2MPa, 1.4MPa, 1.6MPa, 1.8MPa and 2MPa), therefore, fixed pressure is applied to the ceramic wafer through the punch, the bonding degree of the die and the ceramic wafer can be further improved steps, the pressure can be applied through the self gravity of the punch, if the mass of the punch is small, the ceramic wafer can be pressed by a balancing weight, if the pressure is less than 0.1MPa, the bonding effect between the die and the ceramic wafer is relatively poor, the size accuracy of the ceramic shell is not improved, and if the pressure is more than 2MPa, the ceramic wafer is relatively easy to deform, and the quality of the ceramic shell is affected.

, heat-resistant interlayer is set between the ceramic plate and the mould, that is, layers of heat-resistant interlayer are set between the ceramic plate and the male mould and the female mould before sintering, thus, the ceramic plate and the mould are prevented from sticking to in the sintering process, which is not beneficial to demoulding the ceramic shell.

Wherein the heat resistant barrier layer satisfies at least of the following conditions:

the heat-resistant interlayer is the alumina cellucotton, so the alumina cellucotton can bear higher temperature, does not have adverse effect on the die and the ceramic plate, is prepared from materials and has lower cost;

the heat resistant barrier layer has a thickness of less than or equal to 1 mm, such as 1 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.5mm, 0.6 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm. Therefore, the influence of the heat-resistant interlayer with the small thickness on the forming shape of the ceramic sheet is small, and the ceramic shell with the required shape can be obtained; if the thickness is larger than 1 mm, the final shape of the ceramic shell is relatively influenced greatly, and the size precision of the ceramic shell is reduced.

, after the sintering process, may further include polishing the ceramic shell obtained by the sintering process to obtain a ceramic shell with less surface roughness, higher smoothness and smooth hand feeling, wherein the specific steps of the polishing process do not have special requirements, and those skilled in the art can flexibly select the steps according to actual needs, and will not be described herein again.

According to another aspects of the present application, types of 3D ceramic shells are provided, according to an embodiment of the present application, the 3D ceramic shells are manufactured by the method for manufacturing the 3D ceramic shells, so that the ceramic shells have better strength, lower manufacturing cost, higher production yield and higher dimensional accuracy.

According to the embodiment of the application, the ceramic shell has better strength, in embodiments, at least 32g of small balls are hit on the surface of the ceramic shell at a distance of 70 cm from the ceramic shell, and the repetition is carried out for 5 times, so that the ceramic shell has no cracks.

According to another aspects of the present application, there are provided electronic devices, according to an embodiment of the present application, referring to fig. 2, the electronic device includes the aforementioned 3D ceramic housing 100, a display screen assembly 200, the display screen assembly 200 being connected to the 3D ceramic housing 100, a mounting space being defined between the display screen assembly 200 and the 3D ceramic housing 100, and a main board (not shown in fig. 2), the main board being disposed in the mounting space and electrically connected to the display screen assembly.

The specific type of the electronic device has no special requirement, and those skilled in the art can flexibly select the electronic device according to actual requirements, for example, the electronic device may be a mobile phone (see fig. 2), an iPad, a notebook, or the like. According to the embodiment of the present application, the specific category of the electronic device is not particularly required, for example, the specific category of the electronic device includes, but is not limited to, electronic devices such as a mobile phone, a game machine, a television, an iPad, and a kindle. In addition to the chip assembly, the electronic device may further include a structure or a component necessary for a conventional electronic device, and in addition to the chip assembly, a mobile phone may further include a structure or a component necessary for a display panel, a touch panel, a housing assembly, a CPU, a camera module, an audio module, and the like.

Examples

Example 1

The step of preparing the 3D ceramic shell includes:

s100: preparing casting slurry: the casting slurry comprises: 80% of ceramic powder whose main component is zirconia, and the balance of PVA solution whose mass concentration is 5%;

s200: preparing mould powder: the mold powder comprises: 90% of alumina powder and the balance of PVA solution with the mass concentration of 5%;

s300: preparing a ceramic wafer by a tape casting process, wherein the thickness of the ceramic wafer is 0.7 mm;

s400: adding the die powder into an original die, and preparing the needed die by dry pressing, wherein the pressure applied in the dry pressing is 150 MPa;

s500, placing the ceramic wafer in a die comprising a female die and a male die, wherein layers of alumina cellucotton with the thickness of 0.5mm are respectively arranged between the ceramic wafer and the female die and between the ceramic wafer and the male die;

s600; and (5) sintering the mould and the ceramic wafer in the step (S500) in a sintering furnace at 1400 ℃ for 6 hours to obtain the 3D ceramic shell.

Through tests, before and after sintering treatment, the shrinkage rate of the ceramic wafer is 20%, the shrinkage rate of the male die is 21%, the shrinkage rate of the female die is 19%, the prepared ceramic shell is not cracked, 32g of small balls are dropped on the surface of the ceramic shell at a position 70 cm away from the ceramic shell, and the steps are repeated for 5 times, so that the ceramic shell is not cracked; and the dimensional tolerance of the ceramic shell is within a tolerance specification value (+ -70 microns).

Example 2

The step of preparing the 3D ceramic shell includes:

s300: preparing a ceramic wafer by a tape casting process, wherein the thickness of the ceramic wafer is 0.6 mm;

s400: adding the die powder into an original die, and preparing the needed die by dry pressing, wherein the pressure applied in the dry pressing is 130 MPa;

s600: and (5) sintering the mould and the ceramic wafer in the step (S500) in a sintering furnace at 1450 ℃ for 6 hours to obtain the 3D ceramic shell.

Through tests, before and after sintering, the shrinkage rate of the ceramic wafer is 17%, the shrinkage rate of the male die is 18%, the shrinkage rate of the female die is 16%, the prepared ceramic shell is not cracked, 32g of small balls are dropped on the surface of the ceramic shell at a position 70 cm away from the ceramic shell, and the steps are repeated for 5 times, so that the ceramic shell is not cracked; and the dimensional tolerance of the ceramic shell is within a tolerance specification value (+ -70 microns).

Example 3

The step of preparing the 3D ceramic shell includes:

s300: preparing a ceramic wafer by a tape casting process, wherein the thickness of the ceramic wafer is 0.5 mm;

s600: and (5) sintering the mould and the ceramic wafer in the step (S500) in a sintering furnace at 1400 ℃ for 5 hours to obtain the 3D ceramic shell.

Through tests, before and after sintering treatment, the shrinkage rate of the ceramic wafer is 19%, the shrinkage rate of the male die is 20%, the shrinkage rate of the female die is 18%, the prepared ceramic shell is not cracked, 32g of small balls are dropped on the surface of the ceramic shell at a position 70 cm away from the ceramic shell, and the steps are repeated for 5 times, so that the ceramic shell is not cracked; and dimensional tolerances are within tolerance specifications (+ -70 microns).

Example 4

The step of preparing the 3D ceramic shell includes:

Through tests, before and after sintering treatment, the shrinkage rate of the ceramic wafer is 19%, the shrinkage rate of the male die is 18%, the shrinkage rate of the female die is 20%, the prepared ceramic shell is cracked, 32g of small balls are dropped on the surface of the ceramic shell at a position 65 cm away from the ceramic shell, and the steps are repeated for 5 times, so that the ceramic shell is cracked; the dimensional tolerances of the ceramic shell are within tolerance specifications (+ -70 microns).

Comparative example 1

The step of preparing the 3D ceramic shell includes:

s300: preparing a ceramic wafer by a tape casting process, wherein the thickness of the ceramic wafer is 1 mm;

s400: adding the die powder into an original die, and preparing the needed die by dry pressing, wherein the pressure applied in the dry pressing is 160 MPa;

s600: and (5) sintering the mould and the ceramic wafer in the step (S500) in a sintering furnace at 1400 ℃ for 4 hours to obtain the 3D ceramic shell.

Through tests, the shrinkage rate of the ceramic wafer is 20%, the shrinkage rate of the male die is 23.5%, the shrinkage rate of the female die is 16%, and the dimensional tolerance of the ceramic shell is beyond the range of tolerance specified values (+/-70 microns) before and after sintering treatment.

Comparative example 2

The step of preparing the 3D ceramic shell includes:

s200: preparing a ceramic wafer by a tape casting process, wherein the thickness of the ceramic wafer is 0.7 mm;

s300, placing the ceramic wafer in a sintered and shaped die, and keeping the material of the die and the die of the embodiment 1;

s400: and (3) sintering the die and the ceramic wafer in the step (S300) in a sintering furnace at 1400 ℃ for 6 hours to obtain the 3D ceramic shell, wherein the 3D ceramic shell is cracked during sintering, and the dimensional tolerance of the ceramic shell is beyond the range of tolerance specified value (+ -70 microns).

Comparative example 3

The step of preparing the 3D ceramic shell includes:

s300, conducting th sintering treatment on the ceramic wafer to obtain flat plate ceramic, wherein the th sintering temperature is 1400 ℃, and the sintering time is 6 hours;

s400, placing the flat ceramic in a sintered and shaped die, and keeping the material of the die and the die of the embodiment 1 at ;

s500: and (5) carrying out second sintering treatment on the flat plate ceramic in the step (S400) in a sintering furnace, wherein the temperature of the second sintering treatment is 1200 ℃, and the time is 5 hours, so that the flat plate ceramic is softened again and is attached to the mold, and the 3D ceramic shell is obtained.

By testing, 32g of the pellets were dropped onto the surface of the ceramic shell at 65 cm from the ceramic shell, repeated 5 times, the ceramic shell cracked, and the dimensional tolerance of the 3D ceramic shell exceeded the tolerance specification (+ -70 microns).

Although embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application, and that variations, modifications, substitutions and alterations may be made to the above embodiments by those of ordinary skill in the art within the scope of the present application.

Claims

1, A method of making a 3D ceramic shell, comprising:

placing the ceramic wafer which is not sintered in a mould for sintering treatment to obtain the 3D ceramic shell,

wherein the difference between the shrinkage rate of the ceramic sheet and the shrinkage rate of the die is less than or equal to 3%.

2. The method according to claim 1, wherein the mold comprises a female mold and a male mold, the male mold has a shrinkage rate greater than that of the ceramic sheet, and the female mold has a shrinkage rate less than that of the ceramic sheet.

3. The method according to claim 1 or 2, wherein the ceramic sheet has a shrinkage of 8% to 23% and the mold has a shrinkage of 5% to 26% before and after the sintering process.

4. The method according to claim 1 or 2, wherein the mold is made by dry pressing mold powder, and the pressure of the dry pressing is 100-200 MPa.

5. The method according to claim 1, wherein the ceramic sheet has a thickness of 0.3 to 1.3 mm.

6. The method according to claim 1 or 5, characterized in that the ceramic sheet is obtained by a casting process.

7. The method of claim 6, wherein the casting paste comprises, in mass percent, based on a total mass of casting pastes forming the ceramic sheet:

40-80% of ceramic powder;

the balance of binder solution, wherein the mass percent of the binder in the binder solution is 3-10%.

8. The method of claim 4, wherein the mold powder comprises, in mass percent, based on the total mass of the mold powder forming the mold:

90% -97% of die powder;

and the balance of a second binder solution, wherein the mass percent of a second binder in the second binder solution is 3-10%.

9. The method according to claim 1 or 2, wherein the sintering treatment is carried out at a temperature of 1200 ℃ to 1500 ℃ for 2 to 6 hours,

optionally, in the sintering process, the pressure of the male die on the ceramic wafer is 0.1-2 MPa.

10. The method according to claim 1 or 2, characterized in that a heat resistant barrier is provided between the ceramic sheet and the mould.

11. The method of claim 10, wherein the heat resistant barrier meets at least of the following conditions:

the heat-resistant interlayer is made of alumina cellucotton;

the thickness of the heat resistant interlayer is less than or equal to 1 millimeter.

12, A3D ceramic shell, characterized by being produced by the method of any of claims 1-11, .

An electronic device of the type , comprising:

the 3D ceramic housing of claim 12;

the display screen assembly is connected with the 3D ceramic shell, and an installation space is defined between the display screen assembly and the 3D ceramic shell; and

the mainboard is arranged in the installation space and electrically connected with the display screen assembly.