High-reflectivity cover film

Abstract

The utility model is applicable to the technical field of cover films, and provides a high-reflectivity cover film which is provided with two polyimide layers and two adhesive layers by arranging a first polyimide protective layer, a metal coating, a first adhesive layer, a second polyimide protective layer and a second adhesive layer, so that the flatness of a product can be improved, the surface roughness can be reduced, and the product quality can be improved. The reflective film is more stable in reflectivity and suitable for large-area chip pasting, the scratch resistance and the oxidation resistance of the reflective film are improved, the service life is prolonged, and the reflection effect of the reflective film is achieved by arranging the metal coating; by arranging the adhesive layer, the application range of the film is widened, and the film is convenient to use; the covering film has the advantages of being high in reflectivity, good in bonding performance, light and thin in material, resistant to bending, long in service life, excellent in optical performance and the like, wherein the reflectivity can reach 90% or above; therefore, the problems that in the prior art, a covering film is prone to yellowing, the reflectivity is reduced, and cracking and even separation are generated are solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of covering films, in particular to a covering film with high reflectivity. Background Art

[0002] With the rapid development of the information and communication industry, the microelectronics industry has developed rapidly. Flexible printed circuit boards (FPC) have emerged and developed rapidly, and are widely used in many fields such as mobile phones, LCD screens, and tablets. The biggest difference between flexible printed circuit boards and PCBs (Printed Circuit Board, rigid printed circuit boards) is that the function of the cover film used in the former exceeds the solder mask ink used in PCBs. It not only acts as a solder mask to prevent FPC from being corroded by dust, moisture, and chemicals, but also reduces the influence of stress during bending. In addition, with the development of the FPC market, the cover film has been given more functions.

[0003] The prior art still has the following deficiencies:

[0004] The surface flatness of the prior art is closely related to the size of the glue particles. Larger particles in the adhesive will affect the flatness of the product's reflective surface, making the surface rougher. Utility Model Content

[0005] The utility model provides a high reflectivity covering film, aiming to solve the problem in the prior art that the surface flatness is closely related to the glue particle size, and the larger particle size in the adhesive will affect the flatness of the product reflective surface, resulting in greater surface roughness.

[0006] The utility model is implemented as follows: a high-reflectivity covering film comprises: a covering film body, wherein the covering film body comprises a first polyimide protective layer, a varnish layer, a metal plating layer, a second polyimide protective layer and a release layer; a first adhesive layer is arranged between the metal plating layer and the second polyimide protective layer, and a second adhesive layer is arranged between the second polyimide protective layer and the release layer; a PET optical film is bonded to the top of the first polyimide protective layer.

[0007] Preferably, the varnish layer has a thickness of 1 to 50 μm; the first polyimide protective layer and the second polyimide protective layer have a thickness of 3 to 50 μm; and the metal plating layer has a thickness of 0.1 to 3 μm.

[0008] Preferably, the metal coating is aluminum foil, silver foil, gold foil or copper foil, and the metal coating is formed by evaporation or sputtering.

[0009] Preferably, the material of the first adhesive layer and the second adhesive layer is a conventional epoxy resin adhesive system, to which a flame retardant is added to improve the flame resistance.

[0010] Preferably, the thickness of the first adhesive layer and the thickness of the second adhesive layer are both -μm.

[0011] Preferably, the release layer is a carrier film layer or a release paper layer or an optical-grade PET release film layer that has been pre-shrunk.

[0012] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0013] By setting a first polyimide protective layer, a metal plating layer, a first adhesive layer, a second polyimide protective layer and a second adhesive layer, there are two polyimide layers and two adhesive layers, which can improve the flatness of the product, reduce the surface roughness, make the reflectivity more stable, and be suitable for large-area sheet pasting, improve the scratch resistance and oxidation resistance of the reflective film, and increase the service life. The reflective effect of the reflective film is achieved by setting a metal plating layer; by setting an adhesive layer, the application range of the film is increased and the use of the film is convenient; the covering film has the advantages of high reflectivity, good bonding, light and thin material, bending resistance, long service life, excellent optical performance, etc., wherein the reflectivity can reach more than 90%; thereby solving the problems of the covering film in the prior art that is prone to yellowing, the reflectivity is also reduced, cracks are generated, and even detachment occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure of the utility model;

[0015] In the figure: 1. Covering film body; 2. First polyimide protective layer; 3. Varnish layer; 4. Metal plating layer; 5. First adhesive layer; 6. Second polyimide protective layer; 7. Second adhesive layer; 8. Release layer; 9. PET optical film. DETAILED DESCRIPTION

[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0017] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations 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 herein may be combined with other embodiments.

[0018] The utility model embodiment provides a high reflectivity cover film, such as Figure 1 As shown, it includes: a covering film body 1, the covering film body 1 includes a first polyimide protective layer 2, a varnish layer 3, a metal coating 4, a second polyimide protective layer 6 and a release layer 8; a first adhesive layer 5 is arranged between the metal coating 4 and the second polyimide protective layer 6, and a second adhesive layer 7 is arranged between the second polyimide protective layer 6 and the release layer 8; a PET optical film 9 is bonded to the top of the first polyimide protective layer 2.

[0019] It should be noted that, since the surface flatness of the prior art is closely related to the size of the glue particles, the larger particle size in the adhesive will affect the flatness of the product's reflective surface, making the surface roughness larger. This solution has two polyimide layers and two adhesive layers by setting a first polyimide protective layer 2, a metal plating layer 4, a first adhesive layer 5, a second polyimide protective layer 6 and a second adhesive layer 7, which can improve the flatness of the product, reduce the surface roughness, and make the reflectivity more stable. The PET optical film 9 has a smooth and transparent material surface with negligible roughness, so as to meet the physical property requirements of high-transparency polyimide as much as possible.

[0020] In a further preferred embodiment of the present invention, Figure 1 As shown, the thickness of the varnish layer 3 is 1-50 μm; the thickness of the first polyimide protective layer 2 and the second polyimide protective layer 6 is 3-50 μm; and the thickness of the metal plating layer 4 is 0.1-3 μm.

[0021] In this embodiment, the polyimide material has an extremely low water absorption rate, and water vapor is not easy to invade. It also has excellent reliability in high temperature and high humidity environments, a long service life, and is resistant to bending. The material is light and thin, and has good processing performance. There are many types of polyimide (PI), and polyimide materials with high glass transition temperature (Tg), high hardness, high temperature resistance, high L* value, low a*, b* value, high transmittance, low haze, low expansion coefficient, low rebound force, low thermal conductivity, and low refractive index are preferred.

[0022] In a further preferred embodiment of the present invention, Figure 1 As shown, the metal coating 4 is aluminum foil, silver foil, gold foil or copper foil, and the metal coating 4 is formed by evaporation or sputtering.

[0023] In this embodiment, the metal plating layer 4 is used to achieve a high reflection effect of the reflective film.

[0024] In a further preferred embodiment of the present invention, Figure 1 As shown, the material of the first adhesive layer 5 and the second adhesive layer 7 is a conventional epoxy resin adhesive system, wherein a flame retardant is added to improve the flame resistance.

[0025] In a further preferred embodiment of the present invention, Figure 1 As shown, the thickness of the first adhesive layer 5 and the thickness of the second adhesive layer 7 are both 3-100 μm.

[0026] In this embodiment, the flatness of the product surface is ensured.

[0027] In a further preferred embodiment of the present invention, Figure 1 As shown, the release layer 8 is a carrier film layer or a release paper layer or an optical-grade PET release film layer that has been pre-shrunk.

[0028] In this embodiment, the release film 8 is preferably made of an optical-grade PET release film that has been pre-shrunk to ensure the smoothness of the PI layer.

[0029] It should be noted that, for the above-mentioned embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the utility model is not limited by the described action sequence, because according to the utility model, some steps may be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the utility model.

[0030] In the several embodiments provided in the present application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are merely schematic, such as the division of the above-mentioned units. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be in the form of telecommunication or other forms.

[0031] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0032] The above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit the protection scope of the utility model. Obviously, the described embodiments are only some embodiments of the utility model, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model. Although the utility model has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the utility model according to the circumstances without conflict, without making creative work, so as to obtain different other technical solutions that do not deviate from the concept of the utility model in essence, and these technical solutions also belong to the scope of protection of the utility model.

Claims

1. A high reflectivity cover film, characterized in that: include: A covering film body (1), the covering film body (1) comprising a first polyimide protective layer (2), a varnish layer (3), a metal plating layer (4), a second polyimide protective layer (6) and a release layer (8); A first adhesive layer (5) is provided between the metal plating layer (4) and the second polyimide protective layer (6), and a second adhesive layer (7) is provided between the second polyimide protective layer (6) and the release layer (8); A PET optical film (9) is laminated on the top of the first polyimide protective layer (2).

2. The high reflectivity cover film according to claim 1, characterized in that: The varnish layer (3) has a thickness of 1 to 50 μm; The thickness of the first polyimide protective layer (2) and the second polyimide protective layer (6) is 3 to 50 μm; The thickness of the metal coating (4) is 0.1 to 3 μm.

3. The high reflectivity cover film according to claim 2, characterized in that: The metal coating is aluminum foil, silver foil, gold foil or copper foil, and the metal coating is formed by evaporation or sputtering.

4. The high reflectivity cover film according to claim 1, characterized in that: The thickness of the first adhesive layer (5) and the thickness of the second adhesive layer (7) are both 3-100 μm.

5. The high reflectivity cover film according to claim 2, characterized in that: The release layer (8) is a carrier film layer or a release paper layer or an optical-grade PET release film layer that has been pre-shrunk.

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