Middle frame assembly, preparation method thereof and electronic equipment

Abstract

The invention provides a middle frame assembly, a preparation method thereof and electronic equipment. The middle frame assembly provided by the embodiment of the invention comprises a middle frame, wherein the middle frame is provided with a peripheral side surface; the decorative film is attached to the peripheral side face of the middle frame, the decorative film comprises a base material layer, a texture layer and a film coating layer which are sequentially arranged in a stacked mode, and the base material layer is farther away from the middle frame than the film coating layer; the Young's modulus E1 of the base material layer is larger than or equal to 3.0 GPa and smaller than or equal to 4.2 GPa, and the elongation at break e of the base material layer is larger than or equal to 130% and smaller than or equal to 159%. The middle frame assembly provided by the embodiment of the invention has a relatively good appearance effect.

Description

Technical Field

[0001] The present application relates to the field of electronics, and in particular to a middle frame assembly and a preparation method thereof, and an electronic device. Background Art

[0002] With the development of technology and the improvement of living standards, people have put forward higher requirements for the visual effects of the appearance of electronic devices. However, the appearance of the middle frame of existing electronic devices is not expressive enough and cannot well meet the needs of consumers. Summary of the invention

[0003] The embodiment of the present application provides a middle frame assembly, which has a good appearance effect.

[0004] A first aspect of the present application provides a middle frame assembly, wherein the middle frame assembly includes:

[0005] A middle frame, the middle frame having a peripheral side surface; and

[0006] A decorative film, wherein the decorative film is attached to the peripheral side surface of the middle frame, and the decorative film comprises a substrate layer, a texture layer and a coating layer which are stacked in sequence, and the substrate layer is farther away from the middle frame than the coating layer; the Young's modulus E1 of the substrate layer is in the range of 3.0 GPa ≤ E1 ≤ 4.2 GPa, and the elongation at break e of the substrate layer is in the range of 130% ≤ e ≤ 159%.

[0007] A second aspect of the present application provides a method for preparing a middle frame assembly, which includes:

[0008] Providing a middle frame, wherein the middle frame has a peripheral side surface;

[0009] A decorative film is provided, wherein the decorative film comprises a substrate layer, a texture layer and a coating layer which are sequentially stacked, the Young's modulus E1 of the substrate layer is in the range of 3.0 GPa≤E1≤4.2 GPa, and the elongation at break e of the substrate layer is in the range of 130%≤e≤159%; and

[0010] The decorative film is attached to the peripheral side surface of the middle frame, and the substrate layer is further away from the middle frame than the coating layer.

[0011] A third aspect of the present application provides an electronic device, comprising:

[0012] Display screen;

[0013] The middle frame assembly according to the first aspect of the present application, wherein the middle frame assembly is used to support the display screen; and

[0014] A processor is carried by the middle frame assembly and is electrically connected to the display screen to control the display screen to display.

[0015] The middle frame assembly of the embodiment of the present application includes a middle frame and a decorative film, the decorative film is attached to the peripheral side of the middle frame, and the decorative film includes a base layer, a texture layer and a coating layer stacked in sequence. The texture layer and coating layer of the decorative film of the embodiment of the present application are first formed on the base layer, and then attached to the middle frame by bonding. Compared with directly forming the texture layer and coating layer on the middle frame, the preparation yield of the texture layer and coating layer can be greatly improved, thereby reducing the probability of scrapping the middle frame and reducing the preparation cost of the middle frame assembly. In addition, the coating layer can make the decorative film have a colorful effect or a metallic highlight effect. Furthermore, by making the Young's modulus E1 of the substrate layer in the range of: 3.0GPa≤E1≤4.2GPa, and the elongation at break e of the substrate layer in the range of: 130%≤e≤159%, the decorative film has good hardness and flexibility, and can be well fitted to the middle frame, especially the bending part of the middle frame can be well fitted with the decorative film, which greatly reduces the difficulty of fitting the decorative film; and the substrate layer is closer to the outer surface of the middle frame than the texture layer and the coating layer. When opening side holes on the middle frame assembly, the decorative film can be better prevented from jumping and cracking, thereby improving the yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a structural schematic diagram of a middle frame assembly according to an embodiment of the present application.

[0018] Figure 2 It is a schematic diagram of the exploded structure of the middle frame assembly of one embodiment of the present application.

[0019] Figure 3 The middle frame component of an embodiment of the present application is Figure 1 Schematic diagram of the cross-sectional structure in the AA direction.

[0020] Figure 4 This application Figure 2 Enlarged view of the dashed box I in the middle.

[0021] Figure 5 The middle frame edge of an embodiment of the present application Figure 1 Schematic diagram of the cross-sectional structure in the BB direction.

[0022] Figure 6 The middle frame component of an embodiment of the present application is Figure 1 Schematic diagram of the cross-sectional structure in the BB direction.

[0023] Figure 7 The middle frame assembly of another embodiment of the present application is Figure 1 Schematic diagram of the cross-sectional structure in the AA direction.

[0024] Figure 8 It is a middle frame component of another embodiment of the present application. Figure 1 Schematic diagram of the cross-sectional structure in the AA direction.

[0025] Fig. 9 It is a middle frame component of another embodiment of the present application. Figure 1 Schematic diagram of the cross-sectional structure in the AA direction.

[0026] Fig.10 It is a schematic diagram of the exploded structure of a middle frame assembly according to another embodiment of the present application.

[0027] Fig.11 This is a partial view of the middle frame of an embodiment of the present application.

[0028] Fig.12 It is a schematic diagram of the exploded structure of a middle frame assembly according to another embodiment of the present application.

[0029] Fig.13 The middle frame assembly of another embodiment of the present application is Figure 1 Schematic diagram of the cross-sectional structure in the AA direction.

[0030] Fig.14 This is a partial view of a middle frame assembly according to an embodiment of the present application.

[0031] Fig.15 It is a schematic diagram of the exploded structure of a middle frame assembly according to another embodiment of the present application.

[0032] Fig.16 It is a middle frame component of another embodiment of the present application. Figure 1 Schematic diagram of the cross-sectional structure in the BB direction.

[0033] Fig.17 It is a schematic flow chart of a method for preparing a middle frame assembly according to an embodiment of the present application.

[0034] Fig.18 It is a schematic flow chart of a method for preparing a decorative film according to an embodiment of the present application.

[0035] Fig.19 It is a schematic flow chart of a method for preparing a decorative film according to another embodiment of the present application.

[0036] Fig. 20It is a schematic diagram of a process for preparing a middle frame assembly according to an embodiment of the present application.

[0037] Fig.21 It is a schematic diagram of a process for preparing a middle frame assembly according to an embodiment of the present application.

[0038] Fig. 22 It is a schematic diagram of the structure of an electronic device according to an embodiment of the present application.

[0039] Fig.23 It is a schematic diagram of a partial exploded structure of an electronic device according to an embodiment of the present application.

[0040] Fig.24 It is a circuit block diagram of an electronic device according to an embodiment of the present application.

[0041] Description of reference numerals:

[0042] 100-middle frame assembly, 10-middle frame, 11-side surface, 111-straight area, 112-first annular arc surface area, 113-second annular arc surface area, 12-body, 13-protruding portion, 131-first end, 132-second end, 30-decorative film, 38-third end, 39-fourth end, 31-substrate layer, 32-texture layer, 321-texture structure, 33-coating layer, 34-ink layer, 35-adhesive layer, 36-hardening layer, 50-first Decorative strip, 51-first adhesion layer, 52-first primer layer, 53-first topcoat layer, 70-second decorative strip, 71-second adhesion layer, 72-second primer layer, 73-second topcoat layer, 90-third decorative strip, 91-third adhesion layer, 92-third primer layer, 93-third topcoat layer, 400-electronic device, 410-display screen, 420-housing, 430-processor, 450-memory, 470-camera module, 421-light-transmitting part. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0044] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0045] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0046] It should be noted that, for the convenience of explanation, in the embodiments of the present application, the same figure marks represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0047] In order to make the middle frame of the electronic device have a better appearance, the surface of the metal middle frame can be polished, water-plated, anodized or physically vapor deposited (PVD) to show a high-gloss texture, which is the metallic highlight effect. However, this method has a high preparation cost and is only suitable for high-end models. In addition, the plastic middle frame can be directly coated to make the plastic middle frame have a metallic luster. However, the yield of the coating is low, which greatly increases the scrap rate of the middle frame and increases the preparation cost of the middle frame.

[0048] See also Figures 1 to 3 The present application provides a middle frame assembly 100, which includes a middle frame 10 and a decorative film 30. The middle frame 10 has a peripheral side surface 11; the decorative film 30 is attached to the peripheral side surface 11 of the middle frame 10, and the decorative film 30 includes a substrate layer 31, a texture layer 32, and a coating layer 33 stacked in sequence, and the substrate layer 31 is farther away from the middle frame 10 than the coating layer 33; the Young's modulus E1 of the substrate layer 31 is in the range of 3.0GPa≤E1≤4.2GPa, and the elongation at break e of the substrate layer 31 is in the range of 130%≤e≤159%.

[0049] The middle frame assembly 100 of the embodiment of the present application can be applied to portable electronic devices such as mobile phones, tablet computers, laptop computers, desktop computers, smart bracelets, smart watches, e-readers, game consoles, etc.

[0050] It is understandable that the substrate layer 31 is closer to the outer surface of the middle frame 10 than the coating layer 33. It is understandable that when the middle frame assembly 100 is applied to an electronic device, the decorative film 30 is exposed to the electronic device.

[0051] It should be noted that the elongation at break of the base layer 31 is e=(La-L0) / L0, wherein L0 is the original length of the base layer 31 and La is the length of the base layer 31 when it is broken.

[0052] Specifically, the Young's modulus E1 of the substrate layer 31 may be, but is not limited to, 3.0 GPa, 3.2 GPa, 3.4 GPa, 3.6 GPa, 3.8 GPa, 4.0 GPa, 4.2 GPa, etc. If the Young's modulus E1 of the substrate layer 31 is too large, the rigidity of the substrate layer 31 is too large, which affects the fit between the decorative film 30 and the middle frame 10. In addition, the brittleness of the substrate layer 31 increases, and it is easy to crack when subjected to external force; if the Young's modulus E1 of the substrate layer 31 is too small, the surface hardness of the decorative film 30 is reduced, affecting the wear resistance of the decorative film 30, and making the surface of the decorative film 30 easily scratched.

[0053] Specifically, the elongation at break e of the substrate layer 31 may be, but is not limited to, 130%, 135%, 140%, 145%, 150%, 155%, 159%, etc. If the elongation at break e of the substrate layer 31 is too small, the toughness of the substrate layer 31 is insufficient, which affects the fit between the decorative film 30 and the middle frame 10, thereby affecting the appearance of the middle frame assembly 100; if the elongation at break e of the substrate layer 31 is too large, the substrate layer 31 is too soft, which reduces the hardness of the substrate layer 31, thereby reducing the wear resistance of the decorative film 30, making the surface of the decorative film 30 easily scratched.

[0054] Optionally, the tensile strength of the substrate layer 31 ranges from 180Mpa to 240Mpa. Specifically, the tensile strength of the substrate layer 31 may be, but is not limited to, 180Mpa, 190Mpa, 200Mpa, 210Mpa, 220Mpa, 230Mpa, 240Mpa, and the like. If the tensile strength of the substrate layer 31 is too high, the rigidity of the substrate layer 31 is too large, which affects the fit between the decorative film 30 and the middle frame 10. In addition, the brittleness of the substrate layer 31 increases, and it is easy to crack when subjected to external force; if the tensile strength of the substrate layer 31 is too low, the decorative film 30 is easily broken during the film application process, and the wear resistance of the decorative film 30 is affected. In the embodiment of the present application, when it comes to the numerical range a to b, if not specifically specified, it means that the numerical value can be any numerical value between a and b, including the endpoint numerical value a and the endpoint numerical value b.

[0055] The middle frame assembly 100 of the embodiment of the present application includes a middle frame 10 and a decorative film 30, the decorative film 30 is attached to the peripheral side surface 11 of the middle frame 10, and the decorative film 30 includes a base layer 31, a texture layer 32 and a coating layer 33 stacked in sequence. The texture layer 32 and the coating layer 33 of the decorative film 30 of the embodiment of the present application are first formed on the base layer 31, and then attached to the middle frame 10 by bonding. Compared with directly forming the texture layer 32 and the coating layer 33 on the middle frame 10, the preparation yield of the texture layer 32 and the coating layer 33 can be greatly improved, thereby reducing the probability of scrapping the middle frame 10 and reducing the preparation cost of the middle frame assembly 100. In addition, the coating layer 33 can make the decorative film 30 have a colorful effect or a metallic highlight effect. Furthermore, by making the Young's modulus E1 of the substrate layer 31 in the range of: 3.0GPa≤E1≤4.2GPa, and the elongation at break e of the substrate layer 31 in the range of: 130%≤e≤159%, the decorative film 30 has good hardness and flexibility, and can be well fitted to the middle frame 10, especially the bending part of the middle frame 10 can be well fitted with the decorative film 30, which greatly reduces the difficulty of fitting the decorative film 30; and the substrate layer 31 is closer to the outer surface of the middle frame 10 than the texture layer 32 and the coating layer 33. When the side hole is opened on the middle frame assembly 100, the decorative film 30 can be better prevented from jumping and cracking, thereby improving the yield.

[0056] Optionally, the material of the middle frame 10 may be but is not limited to a resin material, and the resin may be but is not limited to polycarbonate (PC).

[0057] Optionally, the middle frame 10 can be prepared by injection molding. Using resin to prepare the middle frame 10 by injection molding can not only greatly reduce the weight of the middle frame 10, so that the electronic device using the middle frame assembly 100 has a lighter weight, but also facilitate large-scale process production, reducing the preparation cost of the middle frame 10.

[0058] Please also see Figure 2 and Figure 4 In some embodiments, the middle frame 10 includes a main body portion 12 and a protruding portion 13 connected to each other, the main body portion 12 has the peripheral side surface 11, the protruding portion 13 is protruded on the peripheral side surface 11 of the main body portion 12, and along the circumferential direction of the peripheral side surface 11, the protruding portion 13 includes a first end 131 and a second end 132 arranged opposite to each other, and the decorative film 30 includes a third end 38 and a fourth end 39 arranged opposite to each other; the third end 38 is arranged close to the first end 131, and the fourth end 39 is arranged close to the second end 132.

[0059] It can be understood that the main body 12 and the protruding portion 13 are an integral structure. The main body 12 and the protruding portion 13 can be formed by integral injection molding.

[0060] It can be understood that the circumferential direction of the peripheral side surface 11 refers to the extending direction of the peripheral side surface 11 .

[0061] Optionally, an extending direction of the protrusion 13 is perpendicular to an extending direction of the peripheral side surface 11 .

[0062] In this embodiment, a protrusion 13 is provided on the middle frame 10, and the protrusion 13 can be used as a starting position positioning point for pasting the decorative film 30. When pasting the decorative film 30, one of the first end 131 and the second end 132 of the protrusion 13 is used as the starting point for pasting the decorative film 30, and the other is used as the terminal for pasting the decorative film 30. Therefore, there is no need to consider the alignment of the head and tail of the decorative film 30, which simplifies the pasting process and can also beautify the gap where the head and tail of the film are connected, so that the middle frame assembly 100 has a better appearance effect. Furthermore, the protrusion 13 can also be used as a wave-transmitting structure (or antenna seam) of the antenna of the electronic device to prevent the coating layer 33 on the decorative film 30 from affecting the electromagnetic wave signal of the antenna.

[0063] Optionally, the range of the difference between the height h of the protrusion 13 protruding from the main body 12 and the thickness d of the decorative film 30 is: 0≤|hd|≤100μm. Specifically, the difference |hd| between the height h of the protrusion 13 protruding from the main body 12 and the thickness d of the decorative film 30 can be, but is not limited to, 0, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc. The smaller the difference between the height h of the protruding portion 13 protruding from the main body 12 and the thickness d of the decorative film 30 is, the more flush the end of the protruding portion 13 of the middle frame assembly 100 is with the end surface of the decorative film 30. When the difference between the height h of the protruding portion 13 protruding from the main body 12 and the thickness d of the decorative film 30 is too large, after the decorative film 30 is attached to the middle frame 10, the protruding portion 13 is likely to be too protruding or too concave, thereby affecting the appearance of the middle frame assembly 100.

[0064] See also Figure 5Optionally, the height h of the protrusion 13 protruding from the main body 12 is in the range of 0.25mm≤h≤0.4mm; in other words, the height h of the protrusion 13 is in the range of 0.25mm≤h≤0.4mm. Specifically, the height h of the protrusion 13 can be, but is not limited to, 0.25mm, 0.28mm, 0.30mm, 0.32mm, 0.34mm, 0.36mm, 0.38mm, 0.4mm, etc. If the height of the protrusion 13 is too small, the protrusion 13 will be sunken into the decorative film 30 after the decorative film 30 is attached to the middle frame 10, affecting the appearance of the middle frame assembly 100; if the height of the protrusion 13 is too large, the protrusion 13 will protrude too much from the decorative film 30, resulting in a large height difference, which also affects the appearance of the decorative film 30.

[0065] Optionally, along the extension direction of the peripheral side surface 11, the width L of the protrusion 13 is in the range of 0.8mm≤L≤1.5mm. Specifically, the width L of the protrusion 13 may be, but is not limited to, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, etc. If the width of the protrusion 13 is too small, the process difficulty of preparing the protrusion 13 is increased, and in addition, the process difficulty of aligning the decorative film 30 is increased; if the width of the protrusion 13 is too large, after the decorative film 30 is attached, the protrusion 13 is horizontal in the middle of the decorative film 30, so that the gap at the ends of the decorative film 30 is too large, affecting the appearance of the middle frame assembly 100.

[0066] See also Figure 6 , optionally, the range of the gap s1 between the first end 131 and the third end 38 is: 10μm≤s1≤150μm. Specifically, if the gap between the first end 131 and the third end 38 is too small, the difficulty of aligning the decorative film 30 is increased when the decorative film 30 is attached. In addition, it is easy for the decorative film 30 to cover part of the protrusion 13, causing local bulges, affecting the appearance of the attachment; if the gap between the first end 131 and the third end 38 is too large, the gap between the protrusion 13 and the decorative film 30 is visible to the naked eye, affecting the appearance of the middle frame assembly 100.

[0067] Optionally, the range of the gap s2 between the second end 132 and the fourth end 39 is: 10μm≤s2≤150μm. Specifically, if the gap between the second end 132 and the fourth end 39 is too small, the difficulty of aligning the decorative film 30 is increased when the decorative film 30 is attached. In addition, the decorative film 30 is likely to cover part of the protrusion 13, causing local bulges, affecting the appearance of the attachment; if the gap between the second end 132 and the fourth end 39 is too large, the gap between the protrusion 13 and the decorative film 30 is visible to the naked eye, affecting the appearance of the middle frame assembly 100.

[0068] Optionally, the substrate layer 31 may be but is not limited to polyethylene terephthalate (PET), which is a highly crystalline polymer with a smooth and glossy surface, excellent light transmittance and mechanical properties. The substrate layer 31 used for the decorative film 30 plays a role in supporting various functional layers.

[0069] Optionally, the thickness of the substrate layer 31 is 0.15 mm to 0.25 mm, that is, 150 μm to 250 μm. Specifically, the thickness of the substrate layer 31 may be, but is not limited to, 150 μm, 160 μm, 170 μm, 180 μm, 188 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, etc. If the thickness of the substrate layer 31 is too thick, the rigidity of the substrate layer 31 is too large, which affects the lamination of the decorative film 30. If the thickness of the substrate layer 31 is too thin, the cost of preparing the substrate layer 31 is increased.

[0070] See also Figure 7 Optionally, the texture layer 32 includes a surface texture structure 321 located away from the substrate layer 31. Through the cooperation between the texture structure 321 and the coating layer 33, the decorative film 30 can present a texture effect of flowing light and shadow and a colorful effect.

[0071] It should be noted that when the decorative film 30 needs to achieve a metallic highlight effect, the texture layer 32 does not have a texture structure 321; when the decorative film 30 needs to achieve a texture effect of flowing light and shadow, the texture layer 32 has a texture structure 321, so that the texture layer 32 and the coating layer 33 cooperate to present a texture effect of flowing light and shadow and a colorful effect.

[0072] Optionally, the texture layer 32 is coated on the texture mold using light-curing glue (such as UV glue), and the UV glue layer on the texture mold is transferred to the substrate layer 31 , and the texture layer 32 having the texture structure 321 is formed after curing.

[0073] Optionally, the thickness of the texture layer 32 is 8 μm to 12 μm. Specifically, the thickness of the texture layer 32 may be, but is not limited to, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, etc. When the thickness of the texture layer 32 is too thin, it is not conducive to the formation of the texture structure 321 on the texture layer 32. When the thickness of the texture layer 32 is too thick, the thickness of the decorative film 30 is increased, thereby increasing the rigidity of the decorative film 30 as a whole, which is not conducive to the fitting of the decorative film 30 with the middle frame 10.

[0074] Optionally, the coating layer 33 may include but is not limited to at least one of a metal oxide film and a non-conductive metal film (abbreviated as NCVM film). The metal oxide film has a colorful color effect and is also called an optical film, and the non-conductive metal film plays a role in reflecting light and providing a metallic luster effect.

[0075] Optionally, the number of the coating layer 33 may be one or more layers. "Multiple layers" means greater than or equal to two layers.

[0076] Optionally, the total thickness of the coating layer 33 is 50 nm to 400 nm. Specifically, the total thickness of the coating layer 33 may be, but is not limited to, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, etc.

[0077] Optionally, the non-conductive metal film may be, but is not limited to, indium (purity 99.9%) or indium tin alloy. When the non-conductive metal film is indium tin alloy, the mass ratio of indium to tin in the indium tin alloy is 8:2 to 9:1.

[0078] In some embodiments, the metal oxide film may include a primer layer (e.g., a silicon layer) and Ti3O5 / SiO2 alternately stacked in sequence. In other embodiments, the metal oxide film may include a primer layer (e.g., a silicon layer) and Nb2O5 / SiO2 alternately stacked in sequence.

[0079] See also Figure 8 In some embodiments, the decorative film 30 further includes an ink layer 34, which is disposed on the surface of the coating layer 33 away from the substrate layer 31, and is used to shield the middle frame 10 to prevent the color of the middle frame 10 from being revealed. Optionally, the number of layers of the ink is 1 to 5, for example, 3. When the ink layer 34 is multi-layered, the layer of the multi-layer ink layer 34 that is most away from the coating layer 33 has corrosion resistance, so that the coating layer 33 can be better protected.

[0080] Optionally, the dyne value of the surface of the ink layer 34 away from the coating layer 33 is greater than or equal to 40. Specifically, the dyne value of the surface of the ink layer 34 away from the coating layer 33 may be, but is not limited to, 40, 42, 44, 46, etc. In this way, when the decorative film 30 is attached to the middle frame 10, the adhesive can have better adhesion on the ink layer 34.

[0081] Optionally, the raw material components of the ink layer 34 include colored ink, curing agent, diluent and auxiliary agent, etc. The ink layer 34 is formed by screen printing a slurry composed of the raw material components of the ink layer 34 and baking it at 70° C. to 80° C. for 30 min to 60 min.

[0082] Optionally, the total thickness of the ink layer 34 is 15 μm to 25 μm. Specifically, the total thickness of the ink layer 34 may be, but is not limited to, 15 μm, 18 μm, 20 μm, 21 μm, 23 μm, 25 μm, etc.

[0083] See also Figure 7 and Figure 8 In some embodiments, the decorative film 30 further includes a bonding layer 35, which is disposed on a side of the coating layer 33 away from the substrate layer 31, and is used to bond the decorative film 30 to the middle frame 10, and a Young's modulus E2 of the bonding layer 35 is in the range of 1000MPa≤E2≤2000MPa.

[0084] Specifically, the Young's modulus E2 of the adhesive layer 35 may be, but is not limited to, 1000MPa, 1200MPa, 1400MPa, 1600MPa, 1800MPa, 2000MPa, etc. If the Young's modulus of the adhesive layer 35 is too low, the strength of the adhesive layer 35 is insufficient. When the decorative film 30 is attached to the middle frame 10 and the edge chamfer of the middle frame 10 is subjected to computerized numerical control (CNC) processing, the adhesive layer 35 is easily directly broken, resulting in burrs or burrs and other adverse effects, affecting the appearance of the middle frame assembly 100; if the Young's modulus of the adhesive layer 35 is too high, the overall rigidity of the decorative film 30 is too large, and the flexibility is insufficient, which increases the difficulty of attaching the decorative film 30 to the middle frame 10, and even makes it impossible for the decorative film 30 to completely attach to the middle frame 10, affecting the adhesion of the decorative film 30 to the middle frame 10. In this embodiment, by controlling the Young's modulus of the adhesive layer 35 , the decorative film 30 is attached to the middle frame 10 , and when the edge chamfering of the middle frame assembly 100 is performed, burrs, rough edges and other adverse effects are less likely to occur, thereby improving the appearance of the middle frame assembly 100 .

[0085] It can be understood that when the decorative film 30 does not include the ink layer 34, the adhesive layer 35 is arranged on the surface of the coating layer 33 away from the substrate layer 31; when the decorative film 30 includes the ink layer 34, the adhesive layer 35 is arranged on the surface of the ink layer 34 away from the substrate layer 31.

[0086] Optionally, the adhesive layer 35 may be formed of, but not limited to, heat-curing glue or semi-curing glue. Heat-curing glue may be, but not limited to, epoxy resin glue, such as Fuller two-component AB glue 8190. Semi-curing glue may be, but not limited to, 3M UV activated adhesive film EAS-2807.

[0087] In a specific embodiment, the epoxy resin glue includes an epoxy resin monomer and an aliphatic amine curing agent, and the aliphatic amine curing agent includes at least one of aliphatic diamine (EDA), aliphatic triamine (TDA) or aliphatic tetraamine (TETA).

[0088] Optionally, when the decoration film 30 includes both the ink layer 34 and the adhesive layer 35 , the adhesive layer 35 is disposed on a surface of the ink layer 34 that is away from the substrate layer 31 .

[0089] Optionally, the thickness of the adhesive layer 35 is 50 μm to 100 μm. Specifically, the thickness of the adhesive layer 35 may be, but is not limited to, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc. If the thickness of the adhesive layer 35 is too thin, the adhesive performance is insufficient, and the decorative film 30 cannot be well bonded to the middle frame 10. If the thickness of the adhesive layer 35 is too thick, the overall thickness of the decorative film 30 is increased, affecting the appearance of the middle frame assembly 100.

[0090] See also Fig. 9 In some embodiments, the decorative film 30 further includes a hardening layer 36, which is disposed on the surface of the substrate layer 31 away from the middle frame 10, and the water contact angle of the hardening layer 36 is greater than or equal to 105°. The hardening layer 36 is used to improve the hardness and wear resistance of the decorative film 30, and enables the decorative film 30 to have an anti-fingerprint effect.

[0091] Optionally, the water contact angle of the hardened layer 36 may be, but is not limited to, 105°, 106°, 108°, 110°, 112°, 115°, etc. The higher the water contact angle of the hardened layer 36 is, the less likely the paint will adhere to the decorative film 30 during subsequent spraying and trimming, and the better the appearance of the decorative film 30 is.

[0092] Optionally, the hardening layer 36 can be formed by coating a hardening liquid on the surface of the base material layer 31 away from the middle frame 10 and then performing a baking and light curing process.

[0093] Optionally, the thickness of the hardening layer 36 is 5 μm to 10 μm. Specifically, the thickness of the hardening layer 36 may be, but is not limited to, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. If the thickness of the hardening layer 36 is too thin, the wear resistance of the obtained decorative film 30 will be affected. If the thickness of the hardening layer 36 is too thick, the toughness will be too poor, so that the decorative film 30 is prone to cracking when being bent by force, which affects the flexibility of the decorative film 30, thereby affecting the fit between the decorative film 30 and the middle frame 10.

[0094] See also Fig.10In some embodiments, the middle frame assembly 100 further includes a first decorative strip 50 , which is formed on the peripheral side surface 11 of the middle frame 10 , and the first decorative strip 50 is disposed on one side of the decorative film 30 and at least partially covers the decorative film 30 .

[0095] It can be understood that the first decorative strip 50 and the decorative film 30 are sequentially arranged along the thickness direction of the middle frame 10 .

[0096] In order to make the middle frame assembly 100 have a better feel and appearance, usually after the decorative film 30 is attached, the corners of the middle frame assembly 100 are CNC processed to remove excess material and form chamfers. At this time, the color of the middle frame 10 is exposed at the chamfers, affecting the texture of the middle frame assembly 100. In this embodiment, after the decorative film 30 is attached, the first decorative strip 50 is provided on the part of the middle frame 10 exposed by the decorative film 30, so that the middle frame assembly 100 can have a better appearance and improve the refinement of the whole machine.

[0097] Optionally, the decorative film 30 and the first decorative strip 50 may have the same color or different colors. The appearance of the middle frame assembly 100 may be diversified by designing the difference in appearance effects between the decorative film 30 and the first decorative strip 50 .

[0098] See also Fig.11 Optionally, the peripheral side surface 11 includes a straight area 111 and a first annular curved area 112, the first annular curved area 112 is located on one side of the straight area 111 and connected to the straight area 111, the straight area 111 is provided with the decorative film 30, and the first annular curved area 112 is formed with the first decorative strip 50. The first annular curved area 112 forms an arc chamfer.

[0099] See also Fig.12 In some embodiments, the middle frame assembly 100 further includes a second decorative strip 70, which is formed on the peripheral side surface 11 of the middle frame 10, and the second decorative strip 70 is arranged on the side of the decorative film 30 away from the first decorative strip 50 and at least partially covers the decorative film 30.

[0100] It can be understood that the first decorative strip 50 , the decorative film 30 and the second decorative strip 70 are sequentially arranged along the thickness direction of the middle frame 10 .

[0101] In order to make the middle frame assembly 100 have a better feel and appearance, usually after the decorative film 30 is attached, the corners of the middle frame assembly 100 are CNC machined to remove the excess material and form chamfers. At this time, the color of the middle frame 10 is exposed at the chamfers, affecting the texture of the middle frame assembly 100. In this embodiment, after the decorative film 30 is attached, the second decorative strip 70 is provided on the part of the middle frame 10 exposed on the side of the decorative film 30 away from the first decorative strip 50. Through the cooperation of the first decorative strip 50, the decorative film 30 and the second decorative strip 70, the middle frame assembly 100 can have a better appearance and improve the refinement of the whole machine.

[0102] Optionally, the decorative film 30 and the second decorative strip 70 may have the same color or different colors. The appearance of the middle frame assembly 100 may be diversified by designing the difference in appearance effects between the decorative film 30 and the second decorative strip 70 .

[0103] Please see again Fig.11 Optionally, the peripheral side surface 11 further includes a second annular curved surface area 113, which is located on the side of the straight area 111 away from the first annular curved surface area 112 and connected to the straight area 111, and the second annular curved surface area 113 is formed with the second decorative strip 70; in other words, in this embodiment, the peripheral side surface 11 includes the first annular curved surface area 112, the straight area 111 and the second annular curved surface area 113 connected in sequence. The second annular curved surface area 113 forms an arc chamfer.

[0104] In some embodiments, when the middle frame assembly 100 is provided with the first decorative strip 50 and the second decorative strip 70 , the first decorative strip 50 and the second decorative strip 70 can be omitted by adjusting the color of the middle frame 10 to be close to the color of the decorative film 30 , thereby simplifying the preparation process and preparation cost of the middle frame assembly 100 .

[0105] See also Fig.13 Optionally, the first decorative strip 50 includes a first adhesion layer 51, a first primer layer 52 and a first topcoat layer 53 which are stacked in sequence, and the first adhesion layer 51 is closer to the middle frame 10 than the first topcoat layer 53; the first primer layer 52 includes a first decorative piece (not shown), and the first decorative piece is dispersed in the first primer layer 52.

[0106] Optionally, the first decorative element includes at least one of silver powder, pearl powder, glitter powder, glitter flakes, sequins, etc.

[0107] Optionally, the thickness of the first adhesion layer 51 ranges from 5 μm to 10 μm; specifically, it may be, but not limited to, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. The thickness of the first primer layer 52 ranges from 8 μm to 12 μm; specifically, it may be, but not limited to, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, etc. The thickness of the first topcoat layer 53 ranges from 15 μm to 20 μm; specifically, it may be, but not limited to, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0108] In this embodiment, by setting the first adhesion layer 51, the adhesion of the first primer layer 52 on the middle frame 10 can be improved. By adding the first decorative piece in the first primer layer 52, not only the appearance effect of the first decorative strip 50 can be improved, so that the first decorative strip 50 has a shiny appearance, but also the shielding power of the first primer layer 52 can be improved to better cover the defects on the surface of the middle frame 10. The first topcoat layer 53 can improve the surface gloss of the first decorative strip 50 and, at the same time, make the first decorative strip 50 have better wear resistance.

[0109] Optionally, along the arrangement direction of the first decorative strip 50 and the decorative film 30, the ratio of the line width w1 of the first decorative strip 50 to the width w of the decorative film 30 is in the range of 0.08≤w1 / w≤0.18. Specifically, the ratio of the line width w1 of the first decorative strip 50 to the width w of the decorative film 30 may be, but is not limited to, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, etc. If the ratio of the line width w1 of the first decorative strip 50 to the width w of the decorative film 30 is too small, the first decorative strip 50 is not obvious, and after the middle frame assembly 100 is assembled in the electronic device, it is difficult to present the effect of the combination of the first decorative strip 50 and the decorative film 30. If the ratio of the line width w1 of the first decorative strip 50 to the width w of the decorative film 30 is too large, the proportion of the first decorative strip 50 and the decorative film 30 is not coordinated, affecting the appearance of the middle frame assembly 100. When the ratio of the line width w1 of the first decorative strip 50 to the width w of the decorative film 30 is 0.08 to 0.18, the first decorative strip 50 and the decorative film 30 can have a better proportion, so that the middle frame assembly 100 has a better appearance.

[0110] Optionally, the line width w1 of the first decorative strip 50 is in the range of 0.8 mm ≤ w1 ≤ 1.3 mm; specifically, the line width w1 of the first decorative strip 50 may be, but is not limited to, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, etc. If the line width of the first decorative strip 50 is too small, a portion of the first decorative strip 50 will be blocked after the middle frame assembly 100 is assembled in the electronic device, which may easily make the exposed portion of the first decorative strip 50 too small or even completely block the first decorative strip 50, affecting the appearance of the first decorative strip 50; if the line width of the first decorative strip 50 is too large, a portion of the first decorative strip 50 exposed after the middle frame assembly 100 is assembled in the electronic device is too large, which may cause the first decorative strip 50 to be out of proportion with the decorative film 30, and also affect the appearance of the middle frame assembly 100.

[0111] Optionally, when the middle frame assembly 100 is assembled in the electronic device, the line width of the first decorative strip 50 is in the range of 0.3 mm to 0.8 mm, so that the line width of the first decorative strip 50 and the width of the decorative film 30 have a better ratio, so that the middle frame assembly 100 has a better appearance.

[0112] Optionally, the width w of the decorative film 30 is in the range of: 4mm≤w≤8mm; specifically, the width w of the decorative film 30 may be, but is not limited to, 4mm, 5mm, 6mm, 7mm, 8mm, etc. If the width of the decorative film 30 is too small, it cannot completely cover the peripheral side surface 11 of the middle frame 10, affecting the appearance of the middle frame assembly 100, or the width ratio of the first decorative strip 50 to the decorative film 30 is out of balance, affecting the appearance of the middle frame assembly 100; if the width of the decorative film 30 is too large, it exceeds the thickness of the middle frame 10, affecting the appearance of the middle frame assembly 100.

[0113] Optionally, the second decorative strip 70 includes a second adhesion layer 71, a second primer layer 72 and a second topcoat layer 73 which are stacked in sequence, and the second adhesion layer 71 is closer to the middle frame 10 than the second topcoat layer 73; the second primer layer 72 includes a second decorative part, and the second decorative part is dispersed in the second primer layer 72.

[0114] Optionally, the second decorative element includes at least one of silver powder, pearl powder, glitter powder, glitter flakes, sequins, etc.

[0115] Optionally, the thickness of the second adhesion layer 71 ranges from 5 μm to 10 μm; specifically, it can be, but not limited to, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. The thickness of the second primer layer 72 ranges from 8 μm to 12 μm; specifically, it can be, but not limited to, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, etc. The thickness of the second topcoat layer 73 ranges from 15 μm to 20 μm; specifically, it can be, but not limited to, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0116] In this embodiment, by setting the second adhesion layer 71, the adhesion of the second primer layer 72 on the middle frame 10 can be improved. By adding the second decorative piece in the second primer layer 72, not only the appearance effect of the second decorative strip 70 can be improved, so that the second decorative strip 70 has a shiny appearance, but also the shielding power of the second primer layer 72 can be improved to better cover the defects on the surface of the middle frame 10. The second topcoat layer 73 can improve the surface gloss of the second decorative strip 70 and, at the same time, make the second decorative strip 70 have better wear resistance.

[0117] Optionally, along the arrangement direction of the first decorative strip 50, the decorative film 30, and the second decorative strip 70: the ratio of the line width w2 of the second decorative strip 70 to the width w of the decorative film 30 is in the range of 0.08≤w2 / w≤0.18. Specifically, the ratio of the line width w2 of the second decorative strip 70 to the width w of the decorative film 30 may be, but is not limited to, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, etc. If the ratio of the line width w2 of the second decorative strip 70 to the width w of the decorative film 30 is too small, the second decorative strip 70 is not obvious, and after the middle frame assembly 100 is assembled in the electronic device, it is difficult to present the effect of the combination of the second decorative strip 70 and the decorative film 30. If the ratio of the line width w2 of the second decorative strip 70 to the width w of the decorative film 30 is too large, the proportion of the second decorative strip 70 to the decorative film 30 is not coordinated, affecting the appearance of the middle frame assembly 100. When the ratio of the line width w2 of the second decorative strip 70 to the width w of the decorative film 30 is 0.08 to 0.18, the second decorative strip 70 and the decorative film 30 can have a better proportion, so that the middle frame assembly 100 has a better appearance.

[0118] Optionally, the line width w2 of the second decorative strip 70 is in the range of 0.8mm≤w2≤1.3mm; specifically, the line width w2 of the second decorative strip 70 may be, but is not limited to, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, etc. If the line width of the second decorative strip 70 is too small, a portion of the second decorative strip 70 will be blocked after the middle frame assembly 100 is assembled in the electronic device, which may easily make the exposed portion of the second decorative strip 70 too small or even completely block the second decorative strip 70, affecting the appearance of the second decorative strip 70; if the line width of the second decorative strip 70 is too large, a portion of the second decorative strip 70 will be exposed too large after the middle frame assembly 100 is assembled in the electronic device, which may cause the proportion of the second decorative strip 70 to the decorative film 30 to be out of balance, which may also affect the appearance of the middle frame assembly 100.

[0119] Optionally, when the middle frame assembly 100 is assembled in the electronic device, the width of the second decorative strip 70 is in the range of 0.3 mm to 0.8 mm, so that the width of the second decorative strip 70 and the width of the decorative film 30 have a better ratio, so that the middle frame assembly 100 has a better appearance.

[0120] For a detailed description of the line widths of the first decorative strip 50 and the decorative film 30 , please refer to the description of the corresponding parts of the above embodiment, which will not be repeated here.

[0121] See also Fig.14 and Fig.15 In some embodiments, the middle frame assembly 100 also includes a third decorative strip 90, which covers the surface of the protrusion 13, and is located between the first decorative strip 50 and the second decorative strip 70, and the opposite ends of the third decorative strip 90 are respectively connected to the first decorative strip 50 and the second decorative strip 70.

[0122] See also Fig.16 Optionally, the third decorative strip 90 includes a third adhesion layer 91, a third primer layer 92 and a third topcoat layer 93 which are stacked in sequence, and the third adhesion layer 91 is closer to the middle frame 10 than the third topcoat layer 93; the third primer layer 92 includes a third decorative piece (not shown), and the third decorative piece is dispersed in the third primer layer 92.

[0123] Optionally, the third decorative element includes at least one of silver powder, pearl powder, glitter powder, glitter flakes, sequins, etc.

[0124] Optionally, the thickness of the third adhesion layer 91 ranges from 5 μm to 10 μm; specifically, it can be, but not limited to, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc. The thickness of the third primer layer 92 ranges from 8 μm to 12 μm; specifically, it can be, but not limited to, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, etc. The thickness of the third topcoat layer 93 ranges from 15 μm to 20 μm; specifically, it can be, but not limited to, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0125] In this embodiment, by setting the third adhesion layer 91, the adhesion of the third primer layer 92 on the middle frame 10 can be improved. By adding the third decorative piece in the third primer layer 92, not only the appearance effect of the third decorative strip 90 can be improved, so that the third decorative strip 90 has a shiny appearance, but also the shielding power of the third primer layer 92 can be improved to better cover the defects on the surface of the middle frame 10. The third topcoat layer 93 can improve the surface gloss of the third decorative strip 90 and, at the same time, make the third decorative strip 90 have better wear resistance.

[0126] The third decorative strip 90 covers the entire protrusion 13, so the line width of the third decorative strip 90 is equivalent to the width of the protrusion 13 and is designed according to the width of the protrusion 13. In other words, the line width of the third decorative strip 90 ranges from 0.8 mm to 1.5 mm.

[0127] The middle frame assembly 100 of the embodiment of the present application can be prepared by the method described in the following embodiments of the present application. In addition, it can also be prepared by other methods. The preparation method of the embodiment of the present application is only one or more preparation methods of the middle frame assembly 100 of the present application, and should not be understood as a limitation on the middle frame assembly 100 provided in the embodiment of the present application.

[0128] See also Fig.17 The present application also provides a method for preparing a middle frame assembly 100, which includes:

[0129] S201, providing a middle frame 10, wherein the middle frame 10 has a peripheral side surface 11;

[0130] Optionally, the material of the middle frame 10 may be, but is not limited to, a resin material. In some embodiments, the material of the middle frame 10 may be, but is not limited to, polycarbonate (PC).

[0131] Optionally, the middle frame 10 includes a connected main body portion 12 and a protruding portion 13, the main body portion 12 has the peripheral side surface 11, the protruding portion 13 is protruded on the peripheral side surface 11 of the main body portion 12, and along the circumferential direction of the peripheral side surface 11, the protruding portion 13 includes a first end 131 and a second end 132 arranged back to back.

[0132] For detailed description of other aspects of the middle frame 10 , please refer to the description of the corresponding parts of the above embodiment, which will not be repeated here.

[0133] S202, providing a decorative film 30, wherein the decorative film 30 comprises a substrate layer 31, a texture layer 32 and a coating layer 33 which are sequentially stacked, the Young's modulus E1 of the substrate layer 31 is in the range of 3.0 GPa≤E1≤4.2 GPa, and the elongation at break e of the substrate layer 31 is in the range of 130%≤e≤159%; and

[0134] It can be understood that there is no order of precedence between S201 and S202. S201 and S202 can be performed simultaneously; S201 can be performed first and S202 can be performed later; or S202 can be performed first and S201 can be performed later.

[0135] S203 , attaching the decorative film 30 to the peripheral side surface 11 of the middle frame 10 , and making the base material layer 31 farther away from the middle frame 10 than the coating layer 33 .

[0136] Optionally, the cut decorative film 30 strips are torn off the release film, and then placed under a 365nm wavelength ultraviolet lamp (UV lamp) for irradiation activation, and the UV energy is controlled at 1500mj / cm 2 Up to 3000mj / cm 2 . After activation, the decorative film 30 is attached to the peripheral side surface 11 of the middle frame 10 by an automatic film attaching device within 10 minutes. Optionally, the decorative film 30 includes a third end 38 and a fourth end 39 arranged opposite to each other. The attaching process first fixes one end of the decorative film 30 (such as the third end 38) to one side of the protrusion 13 (such as the first end 131), and then uses a silicone wheel with a guide and limiting pressure ring to gradually attach the decorative film 30 to the peripheral side surface 11 of the middle frame 10 along the shape of the middle frame 10, and finally ends at the other side of the protrusion 13 (such as the second end 132). Optionally, the fitting gap between the two sides of the protrusion 13 and the decorative film 30 needs to be controlled within 0.15mm to ensure the exquisite appearance of the middle frame assembly 100; finally, the middle frame 10 after attaching the decorative film 30 is placed in a contoured pressure holding fixture for 30 seconds, and the pressure is 1kg / cm 2 Then, the decorative film 30 is placed at room temperature for 24 hours to fully cure.

[0137] The middle frame assembly 100 prepared by the method for preparing the middle frame assembly 100 of the embodiment of the present application includes a middle frame 10 and a decorative film 30, the decorative film 30 is attached to the peripheral side surface 11 of the middle frame 10, and the decorative film 30 includes a base layer 31, a texture layer 32 and a coating layer 33 stacked in sequence. The texture layer 32 and the coating layer 33 of the decorative film 30 of the embodiment of the present application are first formed on the base layer 31, and then attached to the middle frame 10 by bonding. Compared with directly forming the texture layer 32 and the coating layer 33 on the middle frame 10, the preparation yield of the texture layer 32 and the coating layer 33 can be greatly improved, thereby reducing the probability of scrapping the middle frame 10 and reducing the preparation cost of the middle frame assembly 100. In addition, the coating layer 33 can make the decorative film 30 have a colorful effect or a metallic highlight effect. Furthermore, by making the Young's modulus E1 of the substrate layer 31 in the range of: 3.0GPa≤E1≤4.2GPa, and the elongation at break e of the substrate layer 31 in the range of: 130%≤e≤159%, the decorative film 30 has good hardness and flexibility, and can be well fitted to the middle frame 10, especially the bending part of the middle frame 10 can be well fitted with the decorative film 30, which greatly reduces the difficulty of fitting the decorative film 30; and the substrate layer 31 is closer to the outer surface of the middle frame 10 than the texture layer 32 and the coating layer 33. When the side hole is opened on the middle frame assembly 100, the decorative film 30 can be better prevented from jumping and cracking, thereby improving the yield.

[0138] Optionally, in S201, providing the middle frame 10 includes:

[0139] 1) providing a middle frame 10 raw material, and drying the middle frame 10 raw material; and

[0140] Optionally, the raw material of the middle frame 10 is polycarbonate resin (PC resin), and the raw material of the middle frame 10 is dried at 100°C to 120°C (for example, 110°C) for 12h (hours) to 36h (for example, 24h), and then kept warm in an insulation box at 85°C to 95°C (for example, 90°C). Then, the raw material of the middle frame 10 is set in the hopper of the injection molding machine for insulation, and the temperature of the hopper is 90°C to 110°C.

[0141] 2) The dried raw material of the middle frame 10 is used for injection molding to obtain the middle frame 10 .

[0142] Specifically, the injection molding process refers to the process of making semi-finished products of a certain shape through pressurization, injection, cooling, and separation of molten raw materials. The injection molding process mainly includes six stages: mold closing - filling - pressure holding - cooling - mold opening - demolding.

[0143] Optionally, the raw material of the middle frame 10 is heated and melted, and the molten raw material of the middle frame 10 is injected into the injection mold by rod extrusion, and then cooled and demolded to obtain the middle frame 10.

[0144] Optionally, the screw speed is 30r / min to 60r / min; the temperature of the injection mold is 80℃ to 100℃, and during injection molding, the temperature of the front section of the injection molding machine barrel is 260℃ to 280℃, the temperature of the middle section is 260℃ to 290℃, and the temperature of the rear section is 260℃ to 270℃; the temperature of the injection molding machine nozzle is 230℃ to 250℃, the injection time is 16s (seconds), and the cooling time is 24s.

[0145] Optionally, the temperature of the raw material of the middle frame 10 during injection molding (i.e., the injection molding temperature) is 280° C. to 300° C. The injection molding temperature cannot be too low. When the injection molding temperature is lower than 260° C., it is difficult to form. When the injection molding temperature is too high, the raw material of the middle frame 10 is easily decomposed by heat.

[0146] For detailed description of other aspects of the middle frame 10 , please refer to the description of the corresponding parts of the above embodiment, which will not be repeated here.

[0147] See also Fig.18 Optionally, in S202, providing the decorative film 30 includes:

[0148] S2021, providing a substrate layer 31;

[0149] Optionally, the substrate layer 31 may be, but is not limited to, a PET layer.

[0150] For detailed description of other aspects of the substrate layer 31 , please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0151] S2022, forming a texture layer 32 on the substrate layer 31; and

[0152] Optionally, a texture mold is provided, wherein the texture mold has a texture structure 321, and the texture mold is placed on a carrier of a transfer machine with the texture structure 321 facing upward; a different layer of liquid ultraviolet light-curing glue (UV glue) is coated on the texture mold to form a UV glue layer, and a substrate layer 31 is arranged on the surface of the UV glue layer; a roller is used to roll on the substrate layer 31 to make the UV glue layer uniform, and while the roller is used to roll, an LED lamp is moved under the texture mold to follow the irradiation, so that the UV glue layer is initially cured, and the curing energy of the LED lamp is 1200mj to 2600mj; the substrate layer 31 with the initially cured UV glue layer is removed, and the UV glue layer is secondary cured with a mercury lamp, and the curing energy of the mercury lamp is 800mj to 1500mj, to ensure that the UV glue layer is completely cured to form a texture layer 32.

[0153] For detailed description of other aspects of the texture layer 32 , please refer to the description of the corresponding parts of the above embodiment, which will not be repeated here.

[0154] S2023 , forming a coating layer 33 on a surface of the texture layer 32 away from the substrate layer 31 .

[0155] Optionally, the coating layer 33 is plated on the surface of the texture layer 32 away from the substrate layer 31 by electron gun evaporation or magnetron sputtering, so that the decorative film 30 has a metallic luster or a colorful effect.

[0156] The length of the coating time can be determined according to the desired effect. The longer the coating time is, the thicker the coating layer 33 is, and the brighter the metallic luster effect is.

[0157] For detailed description of other aspects of the coating layer 33 , please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0158] See also Fig.19 In some embodiments, providing the decorative film 30 further includes: S2024, forming an ink layer 34 on the surface of the coating layer 33 away from the substrate layer 31.

[0159] Optionally, screen printing is used to form the ink layer 34 on the surface of the coating layer 33 away from the substrate layer 31. Optionally, the ink layer 34 may be formed by multi-layer color matching, and each layer is formed by ink screen printing.

[0160] Optionally, a slurry is prepared by mixing a certain proportion of colored ink, a curing agent, a diluent and an auxiliary agent, and used within 2 hours to prevent curing. The thickness of each ink layer 34 is controlled to be 6 μm to 10 μm; after each layer of colored ink is printed, it is heated and cured at 75° C. to 85° C. (e.g., 80° C.). Optionally, when the ink layer 34 is multi-layered, the curing time of the first several ink layers 34 is 30 minutes, and the curing time of the last ink layer is 90 minutes to ensure that the ink is completely dried.

[0161] For detailed description of other aspects of the ink layer 34 , please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0162] In some embodiments, providing the decorative film 30 further includes: S2025 , laminating an adhesive layer 35 on the surface of the ink layer 34 facing away from the substrate layer 31 .

[0163] Optionally, 3M UV activated adhesive film EAS-2807 is used as the adhesive layer 35, which is self-adhesive before activation. The releasable protective film on one side is first torn off, and then the adhesive layer 35 is bonded to the side of the ink layer 34 away from the substrate layer 31 by a laminating machine.

[0164] In other embodiments, the adhesive layer 35 is formed by dispensing before the decorative film 30 is attached. Specifically, epoxy resin glue (such as Fuller two-component AB glue 8190) is dispensed on the peripheral side surface 11 of the middle frame 10 by a 5-axis dispensing machine, and then the decorative film 30 is attached to the peripheral side surface 11 of the middle frame 10, and the adhesive layer 35 is formed by dispensing before the decorative film 30 is attached. 2 Up to 3kg / cm 2 Maintain the pressure for 1 minute to 3 minutes (e.g. 2 minutes).

[0165] For detailed description of other aspects of the adhesive layer 35 , please refer to the description of the corresponding parts of the above embodiment, which will not be repeated here.

[0166] In some embodiments, providing the decorative film 30 further includes: cutting thin strips.

[0167] Specifically, an infrared laser cutting machine is used to cut the decorative film 30 into thin strips for laminating the plastic straight-edge middle frame 10. The length needs to be controlled within ±0.03mm of the length of the side surface 11 of the middle frame 10 to ensure the fineness of the gap after laminating. Since there is usually a certain offset when the decorative film 30 is laminating, a 0.5mm margin is designed on both sides of the width of the decorative film 30 to improve the accuracy of the film laminating.

[0168] In some embodiments, providing the decorative film 30 further includes: S2026 , forming a hardening layer 36 on a surface of the substrate layer 31 away from the coating layer 33 .

[0169] Optionally, S2026 may be before S2022 or after S2025. In the accompanying drawings of the present application, S2026 is taken as after S2025 for illustration, which should not be construed as a limitation on the present application.

[0170] Optionally, the hardening liquid is coated on the surface of the substrate layer 31 away from the coating layer 33, the solvent is removed by baking, and then the hardening liquid is formed by light curing (such as UV curing). Optionally, the hardening liquid includes a polyurethane acrylate oligomer, a photoinitiator and a volatile solvent. Optionally, the photoinitiator can be but is not limited to at least one of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (Diphenyl(2,4,6-Trimethylbenzoyl)Phosphine Oxide, TPO), propylthioxanthone (ITX), benzophenone (Benzophenone, BP), etc. Optionally, the solvent can be but is not limited to one or more of ethyl acetate, propyl acetate, butyl acetate, cyclohexanone, propylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, isopropyl alcohol, butanone, and methyl butanone.

[0171] For detailed description of other aspects of the hardening layer 36 , please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0172] See also Fig. 20 The present application also provides a method for preparing a middle frame assembly 100, which includes:

[0173] S301, providing a middle frame 10, wherein the middle frame 10 has a peripheral side surface 11;

[0174] S302, providing a decorative film 30, wherein the decorative film 30 comprises a substrate layer 31, a texture layer 32 and a coating layer 33 which are stacked in sequence; and

[0175] S303, attaching the decorative film 30 to the peripheral side surface 11 of the middle frame 10, and making the base material layer 31 farther away from the middle frame 10 than the coating layer 33;

[0176] For a detailed description of S301 to S303, please refer to the description of the corresponding parts of S201 to S203 in the above embodiment.

[0177] S304, performing CNC machining to remove the excess material of the decorative film 30, and forming a first annular arc surface area 112 and a second annular arc surface area 113 on the middle frame 10, wherein the peripheral side surface 11 includes a first annular arc surface area 112, a straight area 111 and a second annular arc surface area 113 connected in sequence, and the decorative film 30 is located in the straight area 111; and

[0178] Since the decorative film 30 has a certain Z-direction offset when being applied, the decorative film 30 is designed with a 0.5mm margin on both sides of the middle frame 10 in the Z direction (i.e., the thickness direction). Therefore, after the decorative film 30 is attached, it is only necessary to use a common CNC machine to remove the margins on both sides; after removing the margins, the edge line R angle of the middle frame 10+ on both sides is 0, and the scratching feel is obvious, so CNC processing is required to form chamfers (i.e., the first annular arc surface area 112 and the second annular arc surface area 113) on the middle frame 10 to optimize the feel. Optionally, the chamfer of the middle frame 10 is controlled to be between R 0.1mm and 0.5mm to ensure the balance between the feel and the appearance. After the CNC is performed to form an arc chamfer, the first annular arc surface area 112 and the second annular arc surface area 113 are exposed. In other words, the decorative film 30 is only set in the straight area 111, and is not set in the first annular arc surface area 112 and the second annular arc surface area 113.

[0179] In the embodiment of the present application, since the substrate layer 31 is closer to the outside than the texture layer 32 and the coating layer 33, paint peeling and paint film cracking are less likely to occur during CNC processing, which can significantly improve the yield.

[0180] For detailed description of other aspects of the first annular arc surface area 112 , the straight area 111 and the second annular arc surface area 113 , please refer to the description of the corresponding parts of the above embodiment, which will not be repeated here.

[0181] S305 , forming a first decorative strip 50 on the first annular arc surface area 112 , and forming a second decorative strip 70 on the second annular arc surface area 113 .

[0182] After CNC removal of excess material and chamfering, the middle frame 10 exposes the material surface (i.e., the first annular arc surface area 112 and the second annular arc surface area 113). It is necessary to protect the material surface by spraying paint (i.e., spray filling) to improve the quality and reliability of the product, beautify the appearance of the material surface, and improve the refinement of the entire machine.

[0183] Optionally, the forming of the first decorative strip 50 in the first annular arc surface area 112 and the forming of the second decorative strip 70 in the second annular arc surface area 113 include: fixing the middle frame 10 with the decorative film 30 on the jig, and then spraying the paint mist of the adhesion layer on the surface of the middle frame 10 by controlling the angle of the spray gun, and curing, so as to form a first adhesion layer 51 in the first annular arc surface area 112 and a second adhesion layer 71 in the second annular arc surface area 113; then spraying primer and curing to form a first primer layer 52 on the surface of the first adhesion layer 51 and a second primer layer 72 on the surface of the second adhesion layer 71; finally spraying topcoat (UV topcoat) and curing to form a first topcoat layer 53 on the first primer layer 52 and a second topcoat layer 73 on the second primer layer 72. Among them, the first decorative strip 50 includes a first adhesion layer 51, a first primer layer 52 and a first topcoat layer 53 which are sequentially stacked on the first annular arc surface area 112; the second decorative strip 70 includes a second adhesion layer 71, a second primer layer 72 and a second topcoat layer 73 which are sequentially stacked on the second annular arc surface area 113.

[0184] Optionally, the curing can be light curing or heat curing, and whether light curing or heat curing is used depends on the type of paint. When heat curing is used for curing, the curing baking temperature is 55°C to 65°C, and the curing baking time is 10min to 15min; when ultraviolet light curing (i.e. UV curing) is used for light curing, the curing energy is 800mj / cm 2 Up to 1100mj / cm 2 .

[0185] For detailed descriptions of other aspects of the first decorative strip 50, the first adhesion layer 51, the first primer layer 52, the first topcoat layer 53, the second decorative strip 70, the second adhesion layer 71, the second primer layer 72 and the second topcoat layer 73, please refer to the description of the corresponding parts of the above embodiments and will not be repeated here.

[0186] In some embodiments, when the middle frame assembly 100 further includes a third decorative strip 90, S305 further includes forming the third decorative strip 90 on the surface of the protrusion 13. For a detailed description of the third decorative strip 90, please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0187] See also Fig.21 In some embodiments, the method for preparing the middle frame assembly 100 further includes: S306 , removing the flying oil (ie, paint) on the surface of the decorative film 30 .

[0188] When performing S305 and forming the first decorative strip 50 and the second decorative strip 70, paint will also be sprayed on the decorative film 30, covering the original effect of the decorative film 30, so it is necessary to remove the flying oil on the surface of the decorative film 30. Specifically, a tape with a certain adhesive force is pasted on the surface of the decorative film 30, and then the tape is torn off to remove the paint on the surface of the decorative film 30, thereby exposing the original effect of the decorative film 30; the adhesive force of the tape ranges from 1.5N / 25mm to 3.5N / 25mm, and the peeling force ranges from 5N / 25mm to 10N / 25mm. Since a hardening layer 36 is provided on the substrate layer 31, the hardening layer 36 is the outermost layer of the decorative film 30, and the hardening layer 36 has a higher water contact angle. Therefore, when paint is sprayed on the surface of the decorative film 30, the paint on the surface of the decorative film 30 can be removed by pasting with the tape to expose the decorative film 30.

[0189] In some embodiments, the method for preparing the middle frame assembly 100 further includes: S307 , opening a side hole on the middle frame assembly 100 , wherein the side hole penetrates the peripheral side surface 11 of the middle frame 10 and the decorative film 30 .

[0190] Optionally, a CNC processing method is used to open a side hole on the middle frame assembly 100. Optionally, the side hole can be used to set a volume button, a power button, a charging port, etc., or as at least one of a speaker hole, a microphone hole (Mic hole), etc. When the middle frame 10 is attached to the decorative film 30, it is difficult to ensure the accurate alignment of the side hole. Therefore, CNC processing is required to expose the volume button, power button, charging port, speaker hole and mic hole to ensure the normal use of the whole machine.

[0191] In the embodiment of the present application, since the substrate layer 31 is closer to the outside than the texture layer 32 and the coating layer 33, it is less likely to cause paint peeling and paint film cracks when performing CNC side holes, which can significantly improve the yield.

[0192] When the color of the middle frame 10 is similar to the color of the decorative film 30 , S305 and S306 may be omitted to simplify the manufacturing process of the middle frame assembly 100 and further reduce the manufacturing cost of the middle frame assembly 100 .

[0193] See also Figure 22 to Figure 24 The embodiment of the present application further provides an electronic device 400, which includes a display screen 410, a middle frame assembly 100 described in the embodiment of the present application, and a processor 430. The middle frame assembly 100 is used to carry the display screen 410; the decorative film 30 of the middle frame assembly 100 is exposed on the display screen 410. The processor 430 is carried by the middle frame assembly 100, and the processor 430 is electrically connected to the display screen 410, and is used to control the display screen 410 to display.

[0194] The electronic device 400 of the embodiment of the present application may be, but is not limited to, a portable electronic device 400 such as a mobile phone, a tablet computer, a laptop computer, a desktop computer, a smart bracelet, a smart watch, an e-reader, a game console, etc.

[0195] For a detailed description of the middle frame assembly 100 , please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0196] Optionally, the display screen 410 may be, but is not limited to, one or more of a liquid crystal display screen, a light emitting diode display screen (LED display screen), a micro light emitting diode display screen (Micro LED display screen), a sub-millimeter light emitting diode display screen (Mini LED display screen), an organic light emitting diode display screen (OLED display screen), etc.

[0197] Optionally, the processor 430 includes one or more general-purpose processors, wherein the general-purpose processor can be any type of device capable of processing electronic instructions, including a central processing unit (CPU), a microprocessor, a microcontroller, a main processor, a controller, and an ASIC, etc. The processor 430 is used to execute various types of digital storage instructions, such as software or firmware programs stored in a memory, which enables the computing device to provide a wide variety of services.

[0198] Optionally, the electronic device 400 of the present application further includes a memory 450. The memory 450 is electrically connected to the processor 430 and is used to store program codes required for the processor 430 to run, program codes required for controlling the display screen 410 and the color-changing film 10, and display contents of the display screen 410.

[0199] Optionally, the memory 450 may include a volatile memory (Volatile Memory), such as a random access memory (Random Access Memory, RAM); the memory 450 may also include a non-volatile memory (NVM), such as a read-only memory (Read-Only Memory, ROM), a flash memory (Flash Memory, FM), a hard disk drive (Hard Disk Drive, HDD) or a solid-state drive (SSD). The memory 450 may also include a combination of the above-mentioned types of memory.

[0200] In some embodiments, the electronic device 400 of the embodiment of the present application further includes a housing 420 and a camera module 470, the housing 420 is disposed on the side of the middle frame assembly 100 away from the display screen 410, and is fixed to the middle frame 10 of the middle frame assembly 100, and the decorative film 30, the first decorative strip 50 and the second decorative strip 70 of the middle frame assembly 100 are exposed in the housing 420 and the display screen 410. The middle frame assembly 100 and the housing 420 enclose a housing space (not shown), and the housing space is used to accommodate the processor 430, the memory 450 and the camera module 470. The camera module 470 is electrically connected to the processor 430, and is used to shoot under the control of the processor 430.

[0201] Optionally, the housing 420 has a light-transmitting portion 421, and the camera module 470 can shoot through the light-transmitting portion 421 on the housing 420, that is, the camera module 470 in this embodiment is a rear camera module 470. It can be understood that in other embodiments, the light-transmitting portion 421 can be set on the display screen 410, that is, the camera module 470 is a front camera module 470. In the schematic diagram of this embodiment, the light-transmitting portion 421 is illustrated as an opening. In other embodiments, the light-transmitting portion 421 may not be an opening, but a light-transmitting material, such as plastic, glass, etc.

[0202] It can be understood that the electronic device 400 described in this embodiment is merely a form of electronic device 400 used by the shell 420, and should not be understood as a limitation on the electronic device 400 provided in this application, nor should it be understood as a limitation on the shell 420 provided in each embodiment of this application.

[0203] Mentioning "embodiment" and "implementation method" in this application means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should also be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, provided that there is no contradiction between them.

[0204] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the above preferred implementation modes, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A middle frame assembly, characterized in that: The middle frame assembly includes: A middle frame, the middle frame having a peripheral side surface; and A decorative film, wherein the decorative film is attached to the peripheral side surface of the middle frame, and the decorative film comprises a substrate layer, a texture layer and a coating layer which are stacked in sequence, and the substrate layer is farther away from the middle frame than the coating layer; the Young's modulus E1 of the substrate layer is in the range of 3.0 GPa ≤ E1 ≤ 4.2 GPa, and the elongation at break e of the substrate layer is in the range of 130% ≤ e ≤ 159%.

2. The middle frame assembly according to claim 1, characterized in that: The middle frame includes a main body portion and a protruding portion connected to each other, the main body portion has the peripheral side surface, the protruding portion is protruded on the peripheral side surface of the main body portion, and along the circumferential direction of the peripheral side surface, the protruding portion includes a first end and a second end arranged opposite to each other, and the decorative film includes a third end and a fourth end arranged opposite to each other; the third end is arranged close to the first end, and the fourth end is arranged close to the second end.

3. The middle frame assembly according to claim 2, characterized in that: The difference between a height h of the protruding portion protruding from the main body and a thickness d of the decorative film is in the range of 0≤|hd|≤100 μm.

4. The middle frame assembly according to claim 2, characterized in that: The range of the gap s1 between the first end and the third end is: 10 μm≤s1≤150 μm; the range of the gap s2 between the second end and the fourth end is: 10 μm≤s2≤150 μm.

5. The middle frame assembly according to claim 1, characterized in that: The decorative film further includes a bonding layer, which is disposed on a side of the coating layer away from the substrate layer and is used to bond the decorative film to the middle frame. The Young's modulus E2 of the bonding layer is in the range of 1000MPa≤E2≤2000MPa.

6. The middle frame assembly according to claim 1, characterized in that: The middle frame assembly further includes a first decorative strip, which is formed on a peripheral side surface of the middle frame, and is disposed on one side of the decorative film and at least partially covers the decorative film.

7. The middle frame assembly according to claim 6, characterized in that: The middle frame assembly further includes a second decorative strip, which is formed on a peripheral side surface of the middle frame, and is disposed on a side of the decorative film away from the first decorative strip and at least partially covers the decorative film.

8. The middle frame assembly according to claim 7, characterized in that: The first decorative strip includes a first adhesion layer, a first primer layer and a first topcoat layer stacked in sequence, the first adhesion layer is closer to the middle frame than the first topcoat layer, the first primer layer includes a first decorative piece, and the first decorative piece is dispersed in the first primer layer; the second decorative strip includes a second adhesion layer, a second primer layer and a second topcoat layer stacked in sequence, the second adhesion layer is closer to the middle frame than the second topcoat layer, the second primer layer includes a second decorative piece, and the second decorative piece is dispersed in the second primer layer.

9. The middle frame assembly according to any one of claims 1 to 8, characterized in that: The decorative film further comprises: A hardening layer is provided on a surface of the substrate layer away from the middle frame, and a water contact angle of the hardening layer is greater than or equal to 105°.

10. A method for preparing a middle frame assembly, characterized in that: include: Providing a middle frame, wherein the middle frame has a peripheral side surface; A decorative film is provided, wherein the decorative film comprises a substrate layer, a texture layer and a coating layer which are sequentially stacked, the Young's modulus E1 of the substrate layer is in the range of 3.0 GPa≤E1≤4.2 GPa, and the elongation at break e of the substrate layer is in the range of 130%≤e≤159%; and The decorative film is attached to the peripheral side surface of the middle frame, and the base material layer is further away from the middle frame than the coating layer.

11. An electronic device, characterized in that: include: Display screen; The middle frame assembly according to any one of claims 1 to 9, wherein the middle frame assembly is used to support the display screen; as well as A processor is carried by the middle frame assembly and is electrically connected to the display screen to control the display screen to display.

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