Mobile phone middle frame and coating process thereof

Abstract

The invention relates to the technical field of film coating, in particular to a mobile phone middle frame and a film coating technology thereof.The film coating technology comprises the following steps that (1) the mobile phone middle frame with the cleaned surface is put into a film coating jig and put into a film coating chamber, and the mobile phone middle frame comprises a first film coating area located on the inner side and a second film coating area located on the outer side; (2) covering the second coating area, and sequentially coating seven times in the first coating area by adopting a physical vapor deposition method; (3) the first coating area is covered, and then seven times of coating is sequentially conducted on the second coating area through the physical vapor deposition method; and (4) the surfaces of the seventh inner coating film layer and the seventh outer coating film layer are coated with AF film layers, and through testing, the mobile phone middle frame coated with the film has excellent adhesive force, hardness and wear resistance and further has excellent boiling resistance, temperature impact resistance, hand sweat resistance, cosmetic resistance, salt mist resistance, oil resistance, low-temperature storage, high-temperature storage, alternating temperature heat resistance, smudginess resistance and solar radiation resistance.

Description

Technical Field

[0001] The present invention relates to the field of film coating technology, and in particular to a mobile phone middle frame and a film coating process thereof. Background Art

[0002] As time progresses, people's demands for mobile phones have become more diverse, extending beyond mere practicality. From keypad phones to touchscreen smartphones, and from plastic to today's metal phones, the vast majority of plastic exterior components have been replaced by metal. Metal components offer excellent thermal conductivity, superior texture, structural strength, and a variety of appearances. Compared to plastic phones, metal phones better meet people's demand for quality.

[0003] The metal midframe has become an indispensable component in metal mobile phones, providing both internal support and aesthetics. Since metal exterior parts are significantly more expensive than plastic, their surface treatments are limited. The industry has consistently selected aluminum as the raw material. Aluminum's lower hardness than steel facilitates CNC cutting, and directly die-casting internal assembly features with die-cast aluminum optimizes CNC processing time, thereby reducing processing costs. However, the varying reactivity of aluminum used in mobile phone midframes leads to corrosion during the production process, which only corrodes the aluminum and leaves other stainless steel elements unaffected. This results in poorly finished anodized surfaces and aesthetics.

[0004] Chinese invention patent application number 201810581788.8 discloses a method for preparing a mobile phone midframe using vacuum coating. The method includes initial forming, forming plastic parts, post-processing, coating, and blanking. Subsequent exterior treatment uses vacuum coating to avoid the problem of only corroding the aluminum during processing, resulting in poor appearance. The resulting mobile phone midframe's appearance is comparable to that of a fully CNC-machined mobile phone midframe. The entire process has a high yield rate, reducing the overall processing cycle and cost of the mobile phone midframe. However, the patent does not disclose the specific steps and parameters for vacuum coating. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies in the prior art, the present invention aims to provide a mobile phone middle frame and a coating process thereof.

[0006] The object of the present invention is achieved through the following technical solution: A coating process for a mobile phone middle frame comprises the following steps:

[0007] (1) placing the mobile phone middle frame after surface cleaning into a coating fixture and placing it into a coating chamber, wherein the mobile phone middle frame includes a first coating area located on the inner side and a second coating area located on the outer side;

[0008] (2) Cover the second coating area, start the vacuum pump and the heating device to heat, and first use the physical vapor deposition method to coat the first coating area seven times in sequence:

[0009] A. Select a first inner coating material and perform a first coating in a reaction gas environment to deposit a first inner coating layer in the first coating area. The first inner coating material is Si-Cr2O3-CrN-CrC and the reaction gas is nitrogen.

[0010] B. Select a second inner coating material and perform a second coating in a reaction gas environment to deposit a second inner coating layer on the surface of the first inner coating layer. The second inner coating material is In-Si-Cr2O3 and Si-TiO2N-Cr2O3, and the reaction gas is acetylene.

[0011] C. Select a third inner coating material and perform a third coating in a reaction gas environment to deposit a third inner coating layer on the surface of the second inner coating layer. The third inner coating material is Si-Cr2O3 and In-Si-Cr2O3, and the reaction gases are acetylene and oxygen.

[0012] D. Select a fourth inner coating material and perform a fourth coating in a reaction gas environment to deposit a fourth inner coating layer on the surface of the third inner coating layer. The fourth inner coating material is Si-Cr2O3 and Si-TiO2N-Cr2O3, and the reaction gases are acetylene and oxygen.

[0013] E. Select a fifth inner coating material and perform a fifth coating in a reaction gas environment to deposit a fifth inner coating layer on the surface of the fourth inner coating layer. The fifth inner coating material is Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC. The reaction gas is oxygen.

[0014] F. Select a sixth inner coating material and perform a sixth coating in a reaction gas environment to deposit a sixth inner coating layer on the surface of the fifth inner coating layer. The sixth inner coating material is In-Si-Cr2O3 and the reaction gases are nitrogen and oxygen.

[0015] G. Select a seventh inner coating material and perform a seventh coating in a reaction gas environment to deposit a seventh inner coating layer on the surface of the sixth inner coating layer, wherein the seventh inner coating material is In-Si-Cr2O3 and the reaction gas is oxygen;

[0016] (3) Cover the first coating area, start the vacuum pump and the heating device to heat, and then use the physical vapor deposition method to coat the second coating area seven times in sequence:

[0017] a. Select a first outer coating material and perform a first coating in a reaction gas environment, and deposit a first outer coating layer in the second coating area, wherein the first outer coating material is Si-Cr2O3-CrN-CrC and the reaction gas is oxygen;

[0018] b. Select a second outer coating material and perform a second coating in a reaction gas environment to deposit a second outer coating layer on the surface of the first outer coating layer, wherein the second outer coating material is Si-Cr2O3 and the reaction gas is nitrogen;

[0019] c. Select a third outer coating material and perform a third coating in a reaction gas environment to deposit a third outer coating layer on the surface of the second outer coating layer, wherein the third outer coating material is Si-Cr2O3 and the reaction gas is nitrogen and oxygen;

[0020] d. Select a fourth outer coating material and perform a fourth coating in a reaction gas environment to deposit a fourth outer coating layer on the surface of the third outer coating layer. The fourth outer coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.1-1.0:0.1-1.0, and the reaction gases are nitrogen and oxygen;

[0021] e. Select a fifth outer coating material and perform a fifth coating in a reaction gas environment to deposit a fifth outer coating layer on the surface of the fourth outer coating layer. The fifth outer coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.1-1.0:0.1-1.0, and the reaction gas is oxygen;

[0022] f. Select a sixth outer coating material and perform a sixth coating in a reaction gas environment to deposit a sixth outer coating layer on the surface of the fifth outer coating layer, wherein the sixth outer coating material is In-Si-Cr2O3 and the reaction gases are nitrogen and oxygen;

[0023] g. Select a seventh outer coating material and perform a seventh coating in a reaction gas environment to deposit a seventh outer coating layer on the surface of the sixth outer coating layer, wherein the seventh outer coating material is In-Si-Cr2O3 and the reaction gas is oxygen;

[0024] (4) An AF film layer is plated on the surface of the seventh inner coating layer and the seventh outer coating layer.

[0025] Preferably, in steps B to C and step Cd, the Si content of the Si-Cr2O3 is 10% to 20% by mass, with the remainder being Cr2O3. Silicon has a high refractive index and a low absorption coefficient, as well as strong substrate adhesion; chromium trioxide has high wear resistance, hardness, and good chemical stability. By strictly controlling the mass ratio of Si to Cr2O3 in the Si-Cr2O3, the coating layer obtained by the coating process of the present invention exhibits excellent hardness, wear resistance, and impact resistance.

[0026] Preferably, in steps FG and steps bc and fg, the mass content of In in-Si-Cr2O3 is 15%-30%, the mass content of Si is 10%-20%, and the balance is Cr2O3. Indium has high transparency, high adhesion, high temperature resistance, and corrosion resistance; silicon has high transparency and strong substrate adhesion; and chromium oxide has high wear resistance, hardness, and good chemical stability. By strictly controlling the mass ratio of In, Si, and Cr2O3 in In-Si-Cr2O3, the coating layer obtained by the coating process of the present invention exhibits excellent flexibility, wear resistance, and chemical stability.

[0027] Preferably, in steps D-E and steps b and e, the mass content of Si in Si-TiO2N-Cr2O3 is 20%-40%, the mass content of TiO2N is 20%-30%, and the balance is Cr2O3. Silicon has high transparency and strong substrate adhesion; titanium dioxide nitride has excellent optical properties; and chromium oxide has high wear resistance, hardness, and good chemical stability. The coating process of the present invention strictly controls the mass ratio of Si, TiO2N, and Cr2O3 in Si-TiO2N-Cr2O3, resulting in a coating layer with excellent wear resistance and chemical stability, and also allows for controllable color of the coating layer.

[0028] Preferably, in steps A, E, and steps a, e, the mass content of Si in Si-Cr2O3-CrN-CrC is 7%-15%, the mass content of Cr2O3 is 25%-40%, the mass content of CrN is 15%-25%, and the balance is CrC. Silicon has high transparency and strong substrate adhesion; chromium trioxide has high wear resistance, hardness, and good chemical stability; chromium nitride has high hardness and good wear resistance; and chromium carbide has high hardness, wear resistance, and corrosion resistance. The coating process of the present invention strictly controls the mass ratio of Si, Cr2O3, CrN, and CrC in Si-Cr2O3-CrN-CrC, resulting in a coating layer with good wear resistance, impact resistance, and corrosion resistance.

[0029] Preferably, in step B, the second inner coating material is a mixture of In-Si-Cr2O3 and Si-TiO2N-Cr2O3 at a mass ratio of 0.1-1.0:0.1-1.0. More preferably, the second inner coating material is a mixture of In-Si-Cr2O3 and Si-TiO2N-Cr2O3 at a mass ratio of 0.5:0.5. The coating process of the present invention strictly controls the mass ratio of In-Si-Cr2O3 and Si-TiO2N-Cr2O3, resulting in a coating layer having good flexibility, wear resistance, and good chemical stability.

[0030] In step C, the third inner coating material is a mixture of Si-Cr2O3 and In-Si-Cr2O3 at a mass ratio of 0.1-1.0:0.1-1.0. More preferably, the third inner coating material is a mixture of Si-Cr2O3 and In-Si-Cr2O3 at a mass ratio of 0.5:0.5. By strictly controlling the mass ratio of Si-Cr2O3 and In-Si-Cr2O3, the coating layer obtained by the coating process of the present invention has excellent hardness, wear resistance, and impact resistance.

[0031] In step D, the fourth inner coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 at a mass ratio of 0.1-1.0:0.1-1.0. More preferably, the fourth inner coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 at a mass ratio of 0.5:0.5. By strictly controlling the mass ratio of Si-Cr2O3 and Si-TiO2N-Cr2O3, the coating layer obtained by the coating process of the present invention has excellent hardness, wear resistance, and impact resistance.

[0032] In step E, the fifth inner coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC at a mass ratio of 0.1-1.0:0.1-1.0. More preferably, the fifth inner coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC at a mass ratio of 0.5:0.5. By strictly controlling the mass ratio of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC, the coating layer obtained by the coating process of the present invention exhibits excellent wear resistance, impact resistance, and corrosion resistance.

[0033] In step d, the fourth outer coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 at a mass ratio of 0.1-1.0:0.1-1.0. More preferably, the fourth outer coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 at a mass ratio of 0.5:0.5. By strictly controlling the mass ratio of Si-Cr2O3 and Si-TiO2N-Cr2O3, the coating layer obtained by the coating process of the present invention has excellent hardness, wear resistance, and impact resistance.

[0034] In step e, the fifth outer coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC at a mass ratio of 0.1-1.0:0.1-1.0. More preferably, the fifth outer coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC at a mass ratio of 0.5:0.5. By strictly controlling the mass ratio of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in the coating process of the present invention, the resulting coating layer has excellent wear resistance, impact resistance, and corrosion resistance.

[0035] Preferably, in steps AG and ag, the coating is performed by vacuum evaporation, vacuum ion plating, or magnetron sputtering. More preferably, magnetron sputtering is used, in which ions bombard a target material, causing atoms on the target surface to splash onto the substrate, forming a thin film. Sputtering coating has good film uniformity and adhesion, and is suitable for large-area coating.

[0036] Preferably, in the steps AG and ag, the gas pressure of the coating is 1.0*10 -4 -1.0*10 -2 Pa, power is 1-15kw, coating temperature is 80-160°C, single coating time is 1-10min, and total coating thickness is 1.5-15.0μm. Under a high vacuum environment, the impurity gas content is low, which is conducive to the formation of high-purity thin films. The deposition temperature affects the crystallization quality and stress of the film, and the appropriate temperature must be selected based on the material properties and process requirements. The coating process of the present invention strictly controls the coating process parameters, and the resulting film has good film uniformity and adhesion.

[0037] Preferably, in steps CG and steps a and cg, the oxygen flow rate is 10-1000 sccm, in step A and steps bd and f, the nitrogen flow rate is 10-1000 sccm, and in step BD, the acetylene flow rate is 10-1000 sccm. The coating process of the present invention can improve the film color and optical transmittance by strictly controlling the gas flow rates.

[0038] Another object of the present invention is achieved through the following technical solution: a mobile phone middle frame, which is manufactured according to the above-mentioned coating process.

[0039] The beneficial effects of the present invention are as follows: the inner side of the mobile phone middle frame of the present invention adopts Si-Cr2O3-CrN-CrC for the first coating, adopts In-Si-Cr2O3 and Si-Cr2O3-CrN-CrC for the second coating, adopts Si-Cr2O3 and In-Si-Cr2O3 for the third coating, adopts Si-Cr2O3 and Si-TiO2N-Cr2O3 for the fourth coating, adopts Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC for the fifth coating, adopts In-Si-Cr2O3 for the sixth coating, and adopts In-Si-Cr2O3 for the seventh coating; the outer side adopts Si-Cr2O3-CrN-Cr C for the first coating, Si-Cr2O3 for the second coating, Si-Cr2O3 for the third coating, Si-Cr2O3 and Si-TiO2N-Cr2O3 for the fourth coating, Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC for the fifth coating, In-Si-Cr2O3 for the sixth coating, In-Si-Cr2O3 for the seventh coating, and then AF film coating. After coating, the middle frame of the mobile phone has excellent adhesion, hardness and wear resistance after testing. It also has excellent resistance to boiling water, temperature shock, hand sweat, cosmetics, salt spray, oil, low temperature storage, high temperature storage, alternating warm and hot, dirt and solar radiation. DETAILED DESCRIPTION

[0040] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the embodiments. The contents mentioned in the embodiments are not intended to limit the present invention.

[0041] Example 1

[0042] A coating process for a mobile phone middle frame includes the following steps:

[0043] (1) placing the mobile phone middle frame after surface cleaning into a coating fixture and placing it into a coating chamber, wherein the mobile phone middle frame includes a first coating area located on the inner side and a second coating area located on the outer side;

[0044] (2) Cover the second coating area, start the vacuum pump and the heating device to heat, and first use the physical vapor deposition method to coat the first coating area seven times in sequence:

[0045] A. Select a first inner coating material and perform a first coating in a reaction gas environment to deposit a first inner coating layer in the first coating area. The first inner coating material is Si-Cr2O3-CrN-CrC and the reaction gas is nitrogen.

[0046] B. Select a second inner coating material and perform a second coating in a reaction gas environment to deposit a second inner coating layer on the surface of the first inner coating layer. The second inner coating material is In-Si-Cr2O3 and Si-Cr2O3-CrN-CrC, and the reaction gas is acetylene.

[0047] C. Select a third inner coating material and perform a third coating in a reaction gas environment to deposit a third inner coating layer on the surface of the second inner coating layer. The third inner coating material is Si-Cr2O3 and In-Si-Cr2O3, and the reaction gases are acetylene and oxygen.

[0048] D. Select a fourth inner coating material and perform a fourth coating in a reaction gas environment to deposit a fourth inner coating layer on the surface of the third inner coating layer. The fourth inner coating material is Si-Cr2O3 and Si-TiO2N-Cr2O3, and the reaction gases are acetylene and oxygen.

[0049] E. Select a fifth inner coating material and perform a fifth coating in a reaction gas environment to deposit a fifth inner coating layer on the surface of the fourth inner coating layer. The fifth inner coating material is Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC. The reaction gas is oxygen.

[0050] F. Select a sixth inner coating material and perform a sixth coating in a reaction gas environment to deposit a sixth inner coating layer on the surface of the fifth inner coating layer. The sixth inner coating material is In-Si-Cr2O3 and the reaction gases are nitrogen and oxygen.

[0051] G. Select a seventh inner coating material and perform a seventh coating in a reaction gas environment to deposit a seventh inner coating layer on the surface of the sixth inner coating layer, wherein the seventh inner coating material is In-Si-Cr2O3 and the reaction gas is oxygen;

[0052] (3) Cover the first coating area, start the vacuum pump and the heating device to heat, and then use the physical vapor deposition method to coat the second coating area seven times in sequence:

[0053] a. Select a first outer coating material and perform a first coating in a reaction gas environment, and deposit a first outer coating layer in the second coating area, wherein the first outer coating material is Si-Cr2O3-CrN-CrC and the reaction gas is oxygen;

[0054] b. Select a second outer coating material and perform a second coating in a reaction gas environment to deposit a second outer coating layer on the surface of the first outer coating layer, wherein the second outer coating material is Si-Cr2O3 and the reaction gas is nitrogen;

[0055] c. Select a third outer coating material and perform a third coating in a reaction gas environment to deposit a third outer coating layer on the surface of the second outer coating layer, wherein the third outer coating material is Si-Cr2O3 and the reaction gas is nitrogen and oxygen;

[0056] d. Select a fourth outer coating material and perform a fourth coating in a reaction gas environment to deposit a fourth outer coating layer on the surface of the third outer coating layer. The fourth outer coating material is Si-Cr2O3 and Si-TiO2N-Cr2O3, and the reaction gases are nitrogen and oxygen.

[0057] e. Selecting a fifth outer coating material and performing a fifth coating in a reaction gas environment to deposit a fifth outer coating layer on the surface of the fourth outer coating layer, wherein the fifth outer coating material is Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC, and the reaction gas is oxygen;

[0058] f. Select a sixth outer coating material and perform a sixth coating in a reaction gas environment to deposit a sixth outer coating layer on the surface of the fifth outer coating layer, wherein the sixth outer coating material is In-Si-Cr2O3 and the reaction gases are nitrogen and oxygen;

[0059] g. Select a seventh outer coating material and perform a seventh coating in a reaction gas environment to deposit a seventh outer coating layer on the surface of the sixth outer coating layer, wherein the seventh outer coating material is In-Si-Cr2O3 and the reaction gas is oxygen;

[0060] (4) An AF film layer is plated on the surface of the seventh inner coating layer and the seventh outer coating layer.

[0061] In the steps BD and cd, the mass content of Si in Si-Cr2O3 is 10%, and the balance is Cr2O3.

[0062] In the steps FG and steps bc and fg, the mass content of In in In-Si-Cr2O3 is 15%, the mass content of Si is 10%, and the balance is Cr2O3.

[0063] In the steps DE and steps b and de, the mass content of Si in Si-TiO2N-Cr2O3 is 20%, the mass content of TiO2N is 20%, and the balance is Cr2O3.

[0064] In the steps A and E and the steps a and e, the mass content of Si in Si-Cr2O3-CrN-CrC is 7%, the mass content of Cr2O3 is 25%, the mass content of CrN is 15%, and the balance is CrC.

[0065] In the step B, the second inner coating material is a mixture of In-Si-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.8:0.2; in the step C, the third inner coating material is a mixture of Si-Cr2O3 and In-Si-Cr2O3 in a mass ratio of 0.8:0.2; in the step D, the fourth inner coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.8:0.2; in the step E, The fifth inner coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.8:0.2; in the step d, the fourth outer coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.8:0.2; in the step e, the fifth outer coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.8:0.2.

[0066] In the steps AG and ag, the coating is performed by magnetron sputtering, and the coating pressure is 5.0*10 -4 Pa, power is 5 kW, coating temperature is 100°C, single coating time is 5 min, total coating thickness is 1.8 μm (six layers in total, each layer is 300 nm thick), in step (3), the AF film layer thickness is 10 nm.

[0067] In step CG and steps a and cg, the flow rate of oxygen is 200 sccm, in step A and steps bd and f, the flow rate of nitrogen is 200 sccm, and in step BD, the flow rate of acetylene is 200 sccm.

[0068] A mobile phone middle frame is manufactured according to the above-mentioned coating process.

[0069] Example 2

[0070] The difference between this embodiment and the above-mentioned embodiment 1 is that in the steps BD and cd, the mass content of Si in Si-Cr2O3 is 15%, and the balance is Cr2O3.

[0071] In the steps FG and the steps bc and fg, the mass content of In in In-Si-Cr2O3 is 22%, the mass content of Si is 15%, and the balance is Cr2O3.

[0072] In the steps DE and steps b and de, the mass content of Si in Si-TiO2N-Cr2O3 is 30%, the mass content of TiO2N is 25%, and the balance is Cr2O3.

[0073] In the steps A and E and the steps a and e, the mass content of Si in Si-Cr2O3-CrN-CrC is 11%, the mass content of Cr2O3 is 32%, the mass content of CrN is 20%, and the balance is CrC.

[0074] In the step B, the second inner coating material is a mixture of In-Si-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.5:0.5; in the step C, the third inner coating material is a mixture of Si-Cr2O3 and In-Si-Cr2O3 in a mass ratio of 0.5:0.5; in the step D, the fourth inner coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.5:0.5; in the step E, The fifth inner coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.5:0.5; in the step d, the fourth outer coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.5:0.5; in the step e, the fifth outer coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.5:0.5.

[0075] In the steps AG and ag, the coating is performed by magnetron sputtering, and the pressure of the coating is 5.0*10 - 3 Pa, power is 10kw, coating temperature is 120℃, single coating time is 8min, total coating thickness is 3.0μm (six layers in total, each layer is 500nm thick), in step (3), the AF film thickness is 30nm.

[0076] In step CG and steps a and cg, the flow rate of oxygen is 250 sccm, in step A and steps bd and f, the flow rate of nitrogen is 250 sccm, and in step BD, the flow rate of acetylene is 250 sccm.

[0077] Example 3

[0078] The difference between this embodiment and the above-mentioned embodiment 1 is that in the steps BD and cd, the mass content of Si in Si-Cr2O3 is 20%, and the balance is Cr2O3.

[0079] In the steps FG and steps bc and fg, the mass content of In in In-Si-Cr2O3 is 15%-30%, the mass content of Si is 20%, and the balance is Cr2O3.

[0080] In the steps DE and steps b and de, the mass content of Si in Si-TiO2N-Cr2O3 is 20%-40%, the mass content of TiO2N is 30%, and the balance is Cr2O3.

[0081] In the steps A and E and the steps a and e, the mass content of Si in Si-Cr2O3-CrN-CrC is 7%-15%, the mass content of Cr2O3 is 40%, the mass content of CrN is 25%, and the balance is CrC.

[0082] In step B, the second inner coating material is a mixture of In-Si-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.2:0.8; in step C, the third inner coating material is a mixture of Si-Cr2O3 and In-Si-Cr2O3 in a mass ratio of 0.2:0.8; in step D, the fourth inner coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.2:0.8; in step E, The fifth inner coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.2:0.8; in the step d, the fourth outer coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.2:0.8; in the step e, the fifth outer coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.2:0.8.

[0083] In the steps AG and ag, the coating is performed by magnetron sputtering, and the pressure of the coating is 8.0*10 - 3 Pa, power is 12kw, coating temperature is 140℃, single coating time is 10min, total coating thickness is 4.8μm (six layers in total, each layer is 800nm ​​thick), in step (3), the AF film thickness is 50nm.

[0084] In step CG and steps a and cg, the flow rate of oxygen is 300 sccm, in step A and steps bd and f, the flow rate of nitrogen is 300 sccm, and in step BD, the flow rate of acetylene is 300 sccm.

[0085] The performance test of the mobile phone middle frame after coating of Examples 1-3 is shown in the following table:

[0086]

[0087]

[0088] As can be seen from the above table, the inner side of the mobile phone middle frame of the present invention is coated with Si-Cr2O3-CrN-CrC for the first time, In-Si-Cr2O3 and Si-Cr2O3-CrN-CrC for the second time, Si-Cr2O3 and In-Si-Cr2O3 for the third time, Si-Cr2O3 and Si-TiO2N-Cr2O3 for the fourth time, Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC for the fifth time, In-Si-Cr2O3 for the sixth time, and In-Si-Cr2O3 for the seventh time; the outer side is coated with Si-Cr2O3-CrN-CrC The first coating is carried out, Si-Cr2O3 is used for the second coating, Si-Cr2O3 is used for the third coating, Si-Cr2O3 and Si-TiO2N-Cr2O3 are used for the fourth coating, Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC are used for the fifth coating, In-Si-Cr2O3 is used for the sixth coating, In-Si-Cr2O3 is used for the seventh coating, and then AF film is coated. After testing, the coated mobile phone middle frame has excellent adhesion, hardness and wear resistance, as well as excellent resistance to boiling water, temperature shock, hand sweat, cosmetics, salt spray, oil, low temperature storage, high temperature storage, alternating warm and hot, dirt and solar radiation.

[0089] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the scope of protection of the present invention.

Claims

1. A coating process for a mobile phone middle frame, characterized in that: The steps include: (1) placing the mobile phone middle frame after surface cleaning into a coating fixture and placing it in a coating chamber, wherein the mobile phone middle frame includes a first coating area located on the inner side and a second coating area located on the outer side; (2) Cover the second coating area, turn on the pump to evacuate and the heating device to heat, and first use the physical vapor deposition method to coat the first coating area seven times in sequence: A. Select a first inner coating material and perform a first coating in a reaction gas environment to deposit a first inner coating layer in a first coating area, wherein the first inner coating material is Si-Cr2O3-CrN-CrC and the reaction gas is nitrogen; B. Select a second inner coating material and perform a second coating in a reaction gas environment to deposit the second inner coating layer on the surface of the first inner coating layer, wherein the second inner coating material is In-Si-Cr2O3 and Si-TiO2N-Cr2O3, and the reaction gas is acetylene; C. Select a third inner coating material and perform a third coating in a reaction gas environment to deposit a third inner coating layer on the surface of the second inner coating layer. The third inner coating material is Si-Cr2O3 and In-Si-Cr2O3, and the reaction gas is acetylene and oxygen. D. Select a fourth inner coating material and perform a fourth coating in a reaction gas environment to deposit a fourth inner coating layer on the surface of the third inner coating layer, wherein the fourth inner coating material is Si-Cr2O3 and Si-TiO2N-Cr2O3, and the reaction gas is acetylene and oxygen; E. Select a fifth inner coating material and perform a fifth coating in a reaction gas environment to deposit a fifth inner coating layer on the surface of the fourth inner coating layer, wherein the fifth inner coating material is Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC, and the reaction gas is oxygen; F. Select a sixth inner coating material and perform a sixth coating in a reaction gas environment to deposit a sixth inner coating layer on the surface of the fifth inner coating layer, wherein the sixth inner coating material is In-Si-Cr2O3, and the reaction gas is nitrogen and oxygen; G. Select a seventh inner coating material and perform a seventh coating in a reaction gas environment to deposit a seventh inner coating layer on the surface of the sixth inner coating layer, wherein the seventh inner coating material is In-Si-Cr2O3 and the reaction gas is oxygen; (3) Cover the first coating area, turn on the pump to evacuate and the heating device to heat, and then use the physical vapor deposition method to coat the second coating area seven times in sequence: a. Select a first outer coating material and perform a first coating in a reaction gas environment, and deposit a first outer coating layer in the second coating area, wherein the first outer coating material is Si-Cr2O3-CrN-CrC, and the reaction gas is oxygen; b. Select a second outer coating material and perform a second coating in a reaction gas environment to deposit the second outer coating layer on the surface of the first outer coating layer, wherein the second outer coating material is Si-Cr2O3 and the reaction gas is nitrogen; c. Select a third outer coating material and perform a third coating in a reaction gas environment to deposit a third outer coating layer on the surface of the second outer coating layer, wherein the third outer coating material is Si-Cr2O3 and the reaction gas is nitrogen and oxygen; d. Select a fourth outer coating material and perform a fourth coating in a reaction gas environment to deposit a fourth outer coating layer on the surface of the third outer coating layer, wherein the fourth outer coating material is Si-Cr2O3 and Si-TiO2N-Cr2O3, and the reaction gas is nitrogen and oxygen; e. Select a fifth outer coating material and perform a fifth coating in a reaction gas environment to deposit a fifth outer coating layer on the surface of the fourth outer coating layer, wherein the fifth outer coating material is Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC, and the reaction gas is oxygen; f. Select a sixth outer coating material and perform a sixth coating in a reaction gas environment to deposit a sixth outer coating layer on the surface of the fifth outer coating layer, wherein the sixth outer coating material is In-Si-Cr2O3, and the reaction gas is nitrogen and oxygen; g. Select a seventh outer coating material and perform a seventh coating in a reaction gas environment to deposit a seventh outer coating layer on the surface of the sixth outer coating layer, wherein the seventh outer coating material is In-Si-Cr2O3 and the reaction gas is oxygen; (4) An AF film layer is coated on the surface of the seventh inner coating layer and the seventh outer coating layer.

2. The coating process for a mobile phone middle frame according to claim 1, characterized in that: In the steps BD and cd, the mass content of Si in Si-Cr2O3 is 10%-20%, and the balance is Cr2O3.

3. The coating process for a mobile phone middle frame according to claim 1, characterized in that: In the step FG and the steps bc and fg, the mass content of In in In-Si-Cr2O3 is 15%-30%, the mass content of Si is 10%-20%, and the balance is Cr2O3.

4. The coating process for a mobile phone middle frame according to claim 1, characterized in that: In the steps DE and steps b and de, the mass content of Si in Si-TiO2N-Cr2O3 is 20%-40%, the mass content of TiO2N is 20%-30%, and the balance is Cr2O3.

5. The coating process for a mobile phone middle frame according to claim 1, characterized in that: In the steps A, E and the steps a, e, the mass content of Si in Si-Cr2O3-CrN-CrC is 7%-15%, the mass content of Cr2O3 is 25%-40%, the mass content of CrN is 15%-25%, and the balance is CrC.

6. The coating process for a mobile phone middle frame according to claim 1, characterized in that: In the step B, the second inner coating material is a mixture of In-Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.1-1.0:0.1-1.0; in the step C, the third inner coating material is a mixture of Si-Cr2O3 and In-Si-Cr2O3 in a mass ratio of 0.1-1.0:0.1-1.0; in the step D, the fourth inner coating material is a mixture of Si-Cr2O3 and Si-Ti02N-Cr2O3 in a mass ratio of 0.1-1.0:0.1-1.0; in the step E, The fifth inner coating material is a mixture of Si-TiO2N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.1-1.0:0.1-1.0; in the step d, the fourth outer coating material is a mixture of Si-Cr2O3 and Si-TiO2N-Cr2O3 in a mass ratio of 0.1-1.0:0.1-1.0; in the step e, the fifth outer coating material is a mixture of Si-Ti02N-Cr2O3 and Si-Cr2O3-CrN-CrC in a mass ratio of 0.1-1.0:0.1-1.

0.

7. The coating process for a mobile phone middle frame according to claim 1, characterized in that: In step AG and step ag, the coating is performed by vacuum evaporation, vacuum ion plating or magnetron sputtering.

8. The coating process for a mobile phone middle frame according to claim 1, characterized in that: In the step AG and the step ag, the gas pressure of the coating is 1.0*10 -4 -1.0*10 -2 Pa, power is 1-15kw, coating temperature is 80-160℃, single coating time is 1-10min, and total coating thickness is 1.5-15.0μm.

9. The coating process for a mobile phone middle frame according to claim 1, characterized in that: In step CG and steps a and cg, the flow rate of oxygen is 10-1000 sccm, in step A and steps bd and f, the flow rate of nitrogen is 10-1000 sccm, and in step BD, the flow rate of acetylene is 10-1000 sccm.

10. A mobile phone middle frame, characterized in that: The mobile phone middle frame is manufactured according to the coating process according to any one of claims 1-9.

Images