Patent Publication Number: US-2019198821-A1

Title: Mask for oled thin-film encapsulation

Description:
FIELD OF INVENTION 
     The present invention relates to a mask, and more particularly to a mask for an OLED thin-film encapsulation. 
     BACKGROUND OF INVENTION 
     OLED (organic light-emitting diode) displays are a new generation of displays. An organic thin-film emits light by forming an organic thin-film on an OLED substrate, where an organic thin-film is disposed between a cathode metal electrode and an anode metal electrode and a voltage is applied to both electrodes. OLED displays, compared to LCD displays, have the following advantages: self-luminous, fast response times, wide viewing angles, saturated colors, and many other advantages, also including being able to achieve a flexible display. For example, by using a flexible plastic substrate to be a carrier, and implement a thin-film encapsulating process, a flexible OLED panel can be achieved. 
     Currently, OLED thin-film encapsulations mainly adopt a structure in which an inorganic layer and an organic layer are stacked. Inorganic layer materials typically used are, for example, SiNx, SiOx, SiON, etc. Organic layer materials commonly use polymer materials. The inorganic layer is used to block water and oxygen. The organic layer mainly disperses stress generated between two inorganic layers. During implementation of the thin-film encapsulation process, a mask needs to be disposed, and there is at least one opening formed in the mask. A region of the opening can form a thin-film layer on a substrate, and the unopened region cannot form the thin-film on the substrate. 
     As illustrated in  FIG. 3 a   , in order to avoid shadowing while using a mask, the mask  302  needs to be closely in contact with a substrate  301  during thin-film formation, the mask  302  forms at least one opening  304 , the thin-film encapsulating material will form a continuous thin-film  303  on the substrate  301 , the mask  302  and a junction of the substrate  301  and the mask  302 . After the thin-film is formed, as illustrated in  FIG. 3 b   , the mask  310  needs to be raised to facilitate picking and placing the substrate  311 . In this case, the continuous thin-film  312  will be broken at the junction of the substrate  301  and the mask  302  (region A) due to the rise of the mask  310 , resulting in a large number of particles being generated. Particles are an important factor of thin-film encapsulation, and when there are many particles in thin-film encapsulating, the thin-film encapsulating will very easily fail. 
     In summary, the mask for an OLED thin-film encapsulation according to the conventional art, the thin-film encapsulating material will form a continuous thin-film on the substrate, the mask and the junction of the substrate, and the mask. After the thin-film is formed, when the mask is raised, the continuous thin-film will be torn due to the rise of the mask, resulting in a large number of particles being generated, thereby impacting effectiveness of thin-film encapsulation. 
     SUMMARY OF THE INVENTION 
     The present invention provides a mask for an OLED thin-film encapsulation, which can prevent the continuous thin-film tearing and resulting in a large number of particles being generated when the mask is raised, thereby ensuring the effectiveness of thin-film encapsulation. 
     In order to solve the above-mentioned problems, the technical solutions provided by the present invention are as follows: 
     The present invention provides a mask for an OLED thin-film encapsulation, comprising: 
     a hollow portion having an opening configured to form a thin-film encapsulation layer on a substrate; and 
     a cover portion configured to cover a non-thin-film encapsulation region on the substrate, wherein the cover portion has a first surface contacting with the substrate, and a second surface away from the substrate; 
     wherein the cover portion has an edge surrounding the opening and close to a side of the cover portion contacting with the substrate, at least one portion of the edge of the cover portion is formed with a beveled corner; an area of the first surface is smaller than an area of the second surface; and the second surface covers the first surface. 
     According to a preferred embodiment of the present invention, the beveled corner is a chamfered corner or a filleted corner. 
     According to a preferred embodiment of the present invention, the edge surrounding the opening has an inner wall formed with a first cutting point, and the first surface is formed with a second cutting point. 
     According to a preferred embodiment of the present invention, the beveled corner is an equilateral orthogonal beveled corner, and an angle between a line from the first cutting point to the second cutting point and a vertical direction of the mask is 45°. 
     According to a preferred embodiment of the present invention, a distance from the first cutting point to the substrate ranges from 15 to 20 um. 
     According to a preferred embodiment of the present invention, the mask for the OLED thin-film encapsulation is configured to form a gap between the thin-film encapsulation layer and an inner wall of the cover portion surrounding the opening. 
     According to a preferred embodiment of the present invention, the gap surrounds the thin-film encapsulation layer. 
     According to a preferred embodiment of the present invention, another gap is formed between the thin-film encapsulation layer formed on the substrate corresponding to a region of the opening and a thin-film encapsulation material attached on the cover portion. 
     According to a preferred embodiment of the present invention, the mask comprises two or more of the hollow portions, and one of the hollow portions is configured to correspondingly form one of the openings. 
     The present invention further provides a mask for an OLED thin-film encapsulation, comprising: 
     a hollow portion having an opening configured to form a thin-film encapsulation layer on a substrate; and 
     a cover portion configured to cover a non-thin-film encapsulation region on the substrate, wherein the cover portion has a first surface contacting with the substrate, and a second surface away from the substrate; 
     wherein the cover portion has an edge surrounding the opening and close to a side of the cover portion contacting with the substrate, and at least one portion of the edge of the cover portion is formed with a beveled corner. 
     According to a preferred embodiment of the present invention, the beveled corner is a chamfered corner or a filleted corner. 
     According to a preferred embodiment of the present invention, the edge surrounding the opening has an inner wall formed with a first cutting point, and the first surface is formed with a second cutting point. 
     According to a preferred embodiment of the present invention, the beveled corner is an equilateral orthogonal beveled corner, and an angle between a line from the first cutting point to the second cutting point and a vertical direction of the mask is 45°. 
     According to a preferred embodiment of the present invention, a distance from the first cutting point to the substrate ranges from 15 to 20 um. 
     According to a preferred embodiment of the present invention, the mask for the OLED thin-film encapsulation is configured to form a gap between the thin-film encapsulation layer and an inner wall of the cover portion surrounding the opening. 
     According to a preferred embodiment of the present invention, the gap surrounds a peripheral of the thin-film encapsulation layer. 
     According to a preferred embodiment of the present invention, another gap is formed between the thin-film encapsulation layer formed on the substrate corresponding to a region of the opening and a thin-film encapsulation material attached on the cover portion. 
     According to a preferred embodiment of the present invention, the mask comprises two or more of the hollow portions, and one of the hollow portions is configured to correspondingly form one of the openings. 
     The present invention has the following advantages: in comparison with the prior art, the present invention provides a mask for an OLED thin-film encapsulation, a side of a mask closing to and contacting with a substrate, a cover portion which has an edge surrounding an opening, at least one portion of the edge of the cover portion is formed with a beveled corner, such that the thin-film formed on the substrate is disconnected with the mask and the thin-film attached on the mask, so as to prevent a continuous thin-film from being formed between the substrate and the mask, thereby preventing the continuous thin-film tearing and resulting in a large number of particles being generated when the mask is raised, thereby ensuring the effectiveness of thin-film encapsulation. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the following drawings, which are intended to be used in the description of the embodiments or the prior art, will be briefly described. It will be apparent that the drawings and the following description are only some embodiments of the present invention. Those of ordinary skill in the art may, without creative efforts, derive other drawings from these drawings. 
         FIG. 1  illustrates a cross-sectional view of a mask for an OLED thin-film encapsulation according to a first embodiment of the present invention. 
         FIG. 2  illustrates a cross-sectional view of a mask for the OLED thin-film encapsulation according to a second embodiment of the present invention. 
         FIG. 3 a    illustrates a cross-sectional view of a mask for an OLED thin-film encapsulation in the conventional art. 
         FIG. 3 b    illustrates a partial view of a mask for an OLED thin-film encapsulation in the conventional art. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The structure and the technical means adopted by the present invention to achieve the above and other objects may be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings. Furthermore, directional terms described by the present invention, such as upper, lower, front, back, left, right, inner, outer, side, longitudinal/vertical, transverse/horizontal, etc., are only directions by referring to the accompanying drawings, and thus the used directional terms are used to describe and understand the present invention, but the present invention is not limited thereto. 
     The present invention is directed against a conventional mask for an OLED thin-film encapsulation, which solves the problem that the mask for an OLED thin-film encapsulation in the conventional art: a continuous thin-film is formed on the substrate, the mask and the junction of the substrate and the mask; the continuous thin-film will be torn when the mask is raised, resulting in a large number of particles being generated; the particles will cause technological problems with the failure of thin-film encapsulation, an embodiment according to the present invention can solve this drawback. 
     Referring now to  FIG. 1 .  FIG. 1  illustrates a cross-sectional view of a mask for an OLED thin-film encapsulation according to a first embodiment of the present invention. The present invention provides a mask for an OLED thin-film encapsulation, comprising a hollow portion having an opening  105  configured to form a thin-film encapsulation layer  103  on a substrate  101 ; and a cover portion  102  configured to cover a non-thin-film encapsulation region on the substrate  101 , wherein the cover portion  102  has a first surface contacting with the substrate  101 , and a second surface away from the substrate  101 ; wherein the cover portion  102  has an edge surrounding the opening  105  and close to a side of the cover portion  102  contacting with the substrate  101 , at least one portion of the edge of the cover portion  102  is formed with a chamfered corner. 
     An area of the first surface is smaller than an area of the second surface, and the second surface covers the first surface. The first surface is opposite to and parallel to the second surface. The edge surrounding the opening  105  has an inner wall formed with a first cutting point  106 , and the first surface is formed with a second cutting point  107 . A distance from the first cutting point  106  to the substrate  101  ranges from 15 to 20 um. The chamfered corner of the cover portion  102  is formed on the mask via the first cutting point  106  and the second cutting point  107 . The opening  105  surrounded by the cover portion  102  has a structure which is a tapering shape. An end of the opening  105  closed to the substrate  101  is larger. The opposite end of the opening  105  is used to define the size of the thin-film encapsulation layer  103 . 
     In a preferred embodiment, the chamfered corner is an equilateral orthogonal beveled corner, and an angle between a line from the first cutting point  106  to the second cutting point  107  and a vertical direction of the mask is 45°. In order to prevent the shadow effect, the mask needs to be closely attached on the substrate  101  so as to implement a thin-film encapsulation process. The thin-film encapsulation material passes through the openings  105  and forms the thin-film encapsulation layer  103  in a region of the substrate  101  corresponding to the opening  105 . The thin-film encapsulation layer  103  includes an inorganic film and an organic film. Since the end of the opening  105  away from the substrate  101  is configured to define the size of the thin-film encapsulation layer  103 , therefore, when one end of the opening  105  closed to the substrate  101  is larger than the other end, an area of the thin-film encapsulation layer  103  formed on the substrate  101  is smaller than an area of the end of the opening  105  closed to the substrate  101 , A gap is formed between the thin-film encapsulation layer  103  and an inner wall of the cover portion surrounding the opening  105 , the gap surrounds the thin-film encapsulation layer  103 . In the film encapsulation process, the cover portion  102  is used to keep out the thin-film encapsulation material in the non-encapsulated area. Therefore, the thin-film encapsulation film  104  is attached on a surface of the cover portion  102 , the cover portion  102  has the edge surrounding the opening  105  and close to the side of the cover portion  102  contacting with the substrate  101 , at least one portion of the edge of the cover portion  102  is formed with a chamfered corner, the distance from the first cutting point  106  to the substrate  101  ranges from 15 to 20 um. In the current thin-film encapsulation, a thickness of the inorganic film generally ranges from 0.5 to 1 um, a thickness of the organic film is generally larger than 10 um. Therefore, another gap is formed between the thin-film encapsulation film  104  attached on the surface of the cover portion  102  and the thin-film encapsulation layer  103  formed on the substrate  101  corresponding to a region of the opening  105 , and at the chamfered corner is in a disconnected state. 
     An angle of the chamfered corner is not limited in the present invention. The angle can be determined according to a specific thickness of the mask and a thickness of the thin-film encapsulation layer, as long as the embodiments can meet that the thin-film encapsulation layer disposed on the substrate, the mask plate and the thin-film encapsulation film attached on the mask are disconnected and a gap can be formed. 
     Refer now to  FIG. 2 .  FIG. 2  illustrates a cross-sectional view of a mask for an OLED thin-film encapsulation according to a second embodiment of the present invention. The present invention provides a mask for an OLED thin-film encapsulation, comprising: a hollow portion having an opening  205  configured to form a thin-film encapsulation layer  203  on a substrate  201 ; and a cover portion  202  configured to cover a non-thin-film encapsulation region on the substrate  201 , wherein the cover portion  202  has a first surface contacting with the substrate  201 , and a second surface away from the substrate  201 ; wherein the cover portion  202  has an edge surrounding the opening  205  and close to a side of the cover portion  202  contacting with the substrate  201 , at least one portion of the edge of the cover portion  202  is formed with a filleted corner. 
     An area of the first surface is smaller than an area of the second surface, and the second surface covers the first surface. The edge surrounding the opening  205  has an inner wall formed with a first cutting point  206 , and the first surface is formed with a second cutting point  207 . The filleted corner is a convex filleted corner. An angle between a line from the first cutting point  206  to the second cutting point  207  and a vertical direction of the mask is 45°. During implementing a thin-film encapsulation process, the thin-film encapsulation material passes through the openings  205  and forms the thin-film encapsulation layer  203  in a region of the substrate  201  corresponding to the opening  205 . The thin-film encapsulation layer  203  includes an inorganic film and an organic film. Since the end of the opening  205  away from the substrate  201  is configured to define the size of the thin-film encapsulation layer  203 , therefore, when one end of the opening  205  closed to the substrate  201  is larger than the other end, an area of the thin-film encapsulation layer  203  formed on the substrate  201  is smaller than an area of the end of the opening  205  closed to the substrate  201 , A gap is formed between the thin-film encapsulation layer  203  and an inner wall of the cover portion surrounding the opening  205 , the gap surrounds the thin-film encapsulation layer  203 . In the film encapsulation process, the cover portion  202  is used to keep out the thin-film encapsulation material in the non-encapsulated area. Therefore, the thin-film encapsulation film  204  is attached on a surface of the cover portion  202 , the cover portion  202  has the edge surrounding the opening  205  and close to the side of the cover portion  202  contacting with the substrate  201 , at least one portion of the edge of the cover portion  202  is formed with a filleted corner, the distance from the first cutting point  206  to the substrate  201  ranges from 15 to 20 um. In the current thin-film encapsulation, a thickness of the inorganic film generally ranges from 0.5 to 1 um, a thickness of the organic film is generally larger than 10 um. Therefore, a gap is formed between the thin-film encapsulation film  204  attached on the surface of the cover portion  202  and the thin-film encapsulation layer  203  formed on the substrate  201  corresponding to a region of the opening  205 , and at the filleted corner is in a disconnected state. 
     An angle of the filleted corner is not limited in the present invention. The angle can be determined according to a specific thickness of the mask and a thickness of the thin-film encapsulation layer, the filleted corner may also be a concave filleted corner, or other shapes, as long as the embodiments can meet that the thin-film encapsulation layer disposed on the substrate, the mask plate and the thin-film encapsulation film attached on the mask are disconnected and a gap can be formed. 
     The present invention further provides a mask for an OLED thin-film encapsulation, the mask comprises two or more of the hollow portions and one of the hollow portions is configured to correspondingly form one of the openings, thereby configured to form a plurality of thin-film encapsulation units on an OLED substrate. The mask surrounding the opening and close to a side of the mask contacting with the substrate, at least one portion of the mask is formed with a beveled corner. The beveled corner may be a chamfered corner, a filleted corner, or other shapes. The mask has a first surface contacting with the OLED substrate, and a second surface away from the OLED substrate. The mask surrounding the opening has an inner wall formed with a first cutting point, and the first surface surrounding the opening is formed with a second cutting point. A distance from the first cutting point to the OLED substrate ranges from 15 to 20 um. A gap is formed between a thin-film encapsulation film attached on a surface of a cover portion and the thin-film encapsulation units formed on the OLED substrate, and is in a disconnected state. Another gap is formed between one of the thin-film encapsulation units and an inner wall of the cover portion surrounding one of the openings, the gap is surrounding the thin-film encapsulation units. An angle of the beveled corner is not limited in the present invention. The angle can be determined according to a specific thickness of the mask and a thickness of the thin-film encapsulation layer. 
     The present invention has the following advantages: in comparison with the prior art, the present invention provides a mask for an OLED thin-film encapsulation, the thin-film formed on the substrate is disconnected with the mask and the thin-film attached on the mask, so as to prevent a continuous thin-film from being formed between the substrate and the mask, thereby preventing the continuous thin-film tearing and resulting in a large number of particles being generated when the mask is raised, thereby ensuring the effectiveness of thin-film encapsulation. 
     In view of the above, although the present invention has been disclosed by way of preferred embodiments, the above preferred embodiments are not intended to limit the present invention, and one of ordinary skill in the art, without departing from the spirit and scope of the invention, the scope of protection of the present invention is defined by the scope of the claims.