Patent Publication Number: US-2016221017-A1

Title: Evaporation mask and method for manufacturing evaporation mask

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Taiwan Patent Application No. 104103483 filed on Feb. 2, 2015, the contents of which are incorporated by reference herein. 
     FIELD 
     The subject matter herein generally relates to an evaporation mask for depositing a thin film on a substrate wherein the evaporation mask has a nonmetallic film dispersed with magnetic particles; the subject matter herein also relates to a method for manufacturing the evaporation mask. 
     BACKGROUND 
     An organic electroluminescent display panel is made by evaporating organic electroluminescent material on a substrate through an evaporation mask. The evaporation mask is made of metal. During the vapor deposition, the evaporation mask is tightly attached to the substrate by using a magnet which attracts the evaporation mask onto the substrate. The evaporation mask is completely made of metal which is difficult to form a masking pattern thereon. Furthermore, the metal has a thermal expansion coefficient quite different from a thermal expansion coefficient of the substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a perspective view of an evaporation mask in accordance with a first embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view the evaporation mask of  FIG. 1 , taken along line thereof 
         FIG. 3  is a flowchart of a method for manufacturing the evaporation mask of  FIG. 1 . 
         FIG. 4  is a perspective view showing mixing magnetic particles and resin particles together to form a main body. 
         FIG. 5  is a perspective view showing a hollow base. 
         FIG. 6  is a perspective view showing the main body adhered to the base. 
         FIG. 7  is a perspective view showing that a plurality of apertures is to be formed in the main body. 
         FIG. 8  is a perspective view of an evaporation mask in accordance with a second embodiment of the present disclosure. 
         FIG. 9  is a cross-sectional view of the evaporation mask of  FIG. 8 , taken along line IX-IX thereof 
         FIG. 10  is a flowchart of a method for manufacturing the evaporation mask of  FIG. 8 . 
         FIG. 11  is a perspective view showing mixing magnetic particles and resin particles together to form a main body. 
         FIG. 12  is a perspective view showing a hollow base. 
         FIG. 13  is a perspective view showing the main body adhered to the base. 
         FIG. 14  is a perspective view showing that a plurality of groups of apertures is to be formed in the main body. 
         FIG. 15  is a perspective view of an evaporation mask in accordance with a third embodiment of the present disclosure. 
         FIG. 16  is a cross-sectional view of the evaporation mask of  FIG. 15 , taken along line XVI-XVI thereof 
         FIG. 17  is a flowchart of a method for manufacturing the evaporation mask of  FIG. 15 . 
         FIG. 18  is a perspective view showing mixing magnetic particles and resin particles together to form a main body 
         FIG. 19  is a perspective view showing the main body adhered to a plate. 
         FIG. 20  is a perspective view showing a photoresist coating applied to a bottom face of the plate. 
         FIG. 21  is a perspective view showing the photoresist coating being subjected to a Hat irradiation through a photo mask. 
         FIG. 22  is a perspective view showing that the photoresist coating becomes a patterned coating. 
         FIG. 23  is a perspective view showing a middle plate defining a plurality of holes therethrough. 
         FIG. 24  is a perspective view showing that the middle plate is to be mounted to a hollow base. 
         FIG. 25  is a perspective view showing that a plurality of groups of apertures is to be formed in the main body. 
         FIG. 26  is a flowchart of a method for using the evaporation mask in accordance with the present disclosure to carry out vapor deposition. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features. The description is not to be considered as limiting the scope of the embodiments described herein. 
     Several definitions that apply throughout this disclosure will now be presented. 
     The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “substantially” is defined to be essentially conforming to the particular dimension, shape or other word that substantially modifies, such that the component need not be exact. For example, substantially cylindrical means that the object resembles a cylinder, but can have one or more deviations from a true cylinder. The term “comprising” means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in a so-described combination, group, series and the like. 
     Referring to  FIG. 1 , a first embodiment of the present disclosure is described in relation to an evaporation mask  100  for use in carrying out a vapor deposition on a display substrate (not shown) so that the display substrate can have organic electroluminescent material thereon to thereby function as a component of a display panel. The evaporation mask  100  has a base  110  and a main body  120  coupled to a center of the base  110 . Each of the base  110  and the main body  120  has a substantially rectangular shape. The base  110  has a frame-like configuration. The main body  120  has a thin plate-like configuration and defines a plurality of square apertures  1211  therethrough to thereby form a pixel pattern  121  which is used for vapor deposition of a patterned film on the display substrate to form a plurality of organic pixels on the display substrate. The apertures  1211  are arranged in a rectangular array. 
     Referring to  FIG. 2 , the base  110  defines an opening  111  in a middle thereof. The main body  120  is mounted on the base  110  and covers the opening  111 . The apertures  1121  extend through the main body  120  to communicate with the opening  111 . The main body  120  has a plurality of magnetic particles  130  evenly dispersed therein. In an alternative embodiment, the base  110  can be omitted; the evaporation mask  100  only requires the main body  120  dispersed with the magnetic particles  130 . The apertures  1121  can be formed by laser processing or etch processing to the main body  120 . 
     The base  110  can be made of class or magnetic metal. In this embodiment, the base  110  is made of Invar, generally known as FeNi36 or 64FeNi which is a nickel-iron alloy notable for its low coefficient of thermal expansion. The main body  120  which is dispersed with the magnetic particles  130  can be coupled to the base  110  by gluing the main body  120  to the base  110 . The magnetic particles  130  can be attracted to the base  110  when the base  110  is made of magnetic metal thereby to enhance the coupling strength between the base  110  and the main body  120 . 
     The main body  120  can be made of resin material such as polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or polysulfone (PSU). In this embodiment, the main body  120  is made of polyimide resin. The apertures  1211  each can have a shape of a square, a rectangle, a circle or an ellipse or any other regular or irregular shape. In this embodiment, the aperture  1211  has a shape of a square. 
     The magnetic particles  130  each can be a round sphere, an elliptical sphere or an irregular sphere. In this embodiment, the magnetic particle  130  is a round sphere having a diameter smaller than 1 μm. When the mametic particle  130  is an elliptical or irregular sphere, the largest dimension of the magnetic particle  130  is not larger than 1 μm. The magnetic particles  130  can be made of magnetic material, paramagnetic material or antimagnetic material. In this embodiment, the magnetic particles  130  can be made of ferromagnetic material such as iron, cobalt, nickel or an alloy thereof, or ferric oxide such as Fe 2 O 3  or Fe 3 O 4 . In this embodiment, the magnetic particles  130  are made Fe 2 O 3 . 
     Referring to  FIG. 26 , a method  400  of using the evaporation mask  100  is disclosed. A flowchart is presented in accordance with an example embodiment. The example method  400  is provided by way of example, as there are a variety of ways to carry out the method. The method  400  described below can be carried out using the configurations illustrated in  FIGS. 1 and 2 , for example, and various elements of these figures are referenced in explaining example method  400 . Each block shown in  FIG. 26  represents one or more processes, methods or subroutines, carried out in the example method  400 . Furthermore, the illustrated order of blocks is illustrative only and the order of the blocks can change according to the present disclosure. Additional blocks can be added or fewer blocks may be utilized, without departing from this disclosure. The example method  400  can begin at block  401 . 
     At block  401 , the evaporation mask  100  is brought to be located over and fixed to an upper top of a display substrate (not shown). To achieve this, a magnetic plate is brought to be located over an underside of the display substrate. By the attraction of the magnetic plate to the magnetic particles  130  dispersed in the main body  120 , the main body  120  can be mametically pulled to the upper face of the display substrate. It can be understood that when the base  110  is made magnetic metal, the base  110  is also magnetically pulled to the upper face of the display substrate. 
     At block  402 , organic electroluminescent material is evaporated to become vapor. The vapor flows through the apertures  1211  to be deposited on the upper face of the display substrate to thereby form organic pixels thereon. 
     Referring to  FIG. 3 , a flowchart is presented in accordance with an example embodiment. The example method  50  is provided by way of example, as there are a variety of ways to carry out the method. The method  50  described below can be carried out to manufacture the evaporation mask  100  illustrated in  FIGS. 1 and 2 . Each block shown in  FIG. 3  represents one or more processes, methods or subroutines, carried out in the example method  50 . Furthermore, the illustrated order of blocks is illustrative only and the order of the blocks can change according to the present disclosure. Additional blocks can be added or fewer blocks may be utilized, without departing from this disclosure. The example method  50  can begin at block  501 . 
     At block  501 , also referring to  FIG. 4 , magnetic particles  130  and resin particles  122  are mixed together and then heat pressed to form the main body  120 . In this embodiment, the resin particles  122  are polyimide resin particles. 
     At block  502 , also referring to  FIG. 5 , the base  110  is provided which is a hollow rectangle defining the central rectangular opening  111  whereby the base  110  has a configuration of a rectangular frame. 
     At block  503 , also referring to  FIG. 6 , the main body  120  is adhered to a center of a top face of the base  110  around the opening  111  to cover the opening  111  of the base  110 . 
     At block  504 , also referring to  FIG. 7 , the main body  120  is processed to form the pixel pattern  121  by using laser beams  80  to form the plurality of apertures  1211  in the main body  120 . Accordingly the evaporation mask  100  in accordance with the first embodiment of the present disclosure is obtained. An area of the pixel pattern  121  is substantially the same as an area of the opening  111 . 
     In an alternative embodiment where the base  110  is not necessary and only the main body  120  dispersed with the magnetic particles  130  is required, then blocks  502  and  503  can be omitted. 
     In the present disclosure, since the main body  120  is made of resin which has a coefficient of expansion (i.e., 3.9 μm/m° C.) similar to a coefficient of expansion (i.e., 3.39 μm/m° C.) of the display substrate for forming a display screen of a computer or mobile phone, during vapor deposition, a relative movement due to thermal expansions of the evaporation mask  100  and the display substrate can be minimized. Furthermore, since the main body  120  is dispersed with the magnetic particles  130  which can be attracted by the magnetic plate located on the underside of the display substrate, an accurate position of the pixel pattern relative to the display substrate can be further assured. Moreover, according to the present disclosure, since the main body  120  is made of resin, the processing of the main body  120  by the laser beams  80  to define the apertures  1211  to thereby form the pixel pattern  121  is relatively easy and time and cost saving. In addition, the precision of dimensions and positions of the apertures  1211  can be enhanced by the laser processing in accordance with the present disclosure. 
     Referring to  FIG. 8 , an evaporation mask  200  in accordance with a second embodiment of the present disclosure is shown. The evaporation mask  200 , like the evaporation mask  100  of the first embodiment, also has a base  210  and a main body  220  located over a top face of the base  210 . The main body  220  defines a plurality of groups of apertures  2211  to define a plurality of pixel patterns  221  each including a corresponding group of apertures  2211 . Each of the base  210  and the main body  220  has a substantially rectangular shape. Each of the groups of apertures  2211  is a rectangular array. 
     Referring to  FIG. 9 , the base  210  defines a rectangular opening  211  in a center thereof. The main body  220  is dispersed with magnetic particles  230  and located over the rectangular opening  211 . The apertures  2211  are all in communication with the opening  211 . 
     Referring to  FIG. 10 , a flowchart is presented in accordance with an example embodiment. The example method  60  is provided by way of example, as there are a variety of ways to carry out the method. The method  60  described below can be carried out to manufacture the evaporation mask  200  illustrated in  FIGS. 8 and 9 . Each block shown in  FIG. 10  represents one or more processes, methods or subroutines, carried out in the example method  60 . Furthermore, the illustrated order of blocks is illustrative only and the order of the blocks can change according to the present disclosure. Additional blocks can be added or fewer blocks may be utilized, without departing from this disclosure. The example method  60  can begin at block  601 . 
     At block  601 , also referring to  FIG. 11 , magnetic particles  230  and resin particles  232  are mixed together and then heat pressed to form the main body  220 . In this embodiment, the resin particles  232  are polyimide resin particles. 
     At block  602 , also referring to  FIG. 12 , the base  210  is provided which is a hollow rectangle defining the central rectangular opening  211  whereby the base  210  has a configuration of a rectangular frame. 
     At block  603 , also referring to  FIG. 13 , the main body  220  is adhered to a center of a top face of the base  210  around the opening  211  to cover the opening  211  of the base  210 . 
     At block  604 , also referring to  FIG. 14 , the main body  120  is processed to form the plurality of pixel patterns  221  by using laser beams  80  to form the plurality of groups of apertures  1211  in the main body  220 . Accordingly the evaporation mask  200  in accordance with the second embodiment of the present disclosure is obtained. A display substrate which is subjected to vapor deposition by using the evaporation mask  200  can obtain a plurality of pixel patterns thereon. By severing the display substrate according the pixel patterns, a plurality of display sub-substrates each of which can be used for constituting a display screen can be obtained. 
     Referring to  FIG. 15 , an evaporation mask  300  in accordance with a third embodiment of the present disclosure is shown. The evaporation mask  300  includes a base  310 , a middle plate  340  over the base  310  and a main body  320  over the middle plate  340 . Each of the base  320 , the middle plate  340  and the base  310  is substantially rectangular in shape. The base  310  and the middle plate  340  have substantially the same size, while the main body  310  has a smaller size and is located over a center of the middle plate  340 . The main body  340  defines a plurality of groups of apertures  3211  therein to define a plurality of pixel patterns  321  each corresponding to a group of apertures  3211  which is arranged in a rectangular array. 
     Referring to  FIG. 16 , the base  310  defines a central, rectangular opening  311  therethrough. The middle plate  340  defines a plurality of rectangular holes  341  communicating with the rectangular opening  311 . The main body  320  is located over a top face of the middle plate  340  to cover the holes  341  and the opening  311 , wherein all of the apertures  3211  of the main body  320  communicate with the holes  341  and the opening  311 . A plurality of magnetic particles  330  is dispersed in the main body  320 . 
     Referring to  FIG. 17 , a flowchart is presented in accordance with an example embodiment. The example method  70  is provided by way of example, as there are a variety of ways to carry out the method. The method  70  described below can be carried out to manufacture the evaporation mask  300  illustrated in  FIGS. 15 and 16 . Each block shown in  FIG. 17  represents one or more processes, methods or subroutines, carried out in the example method  70 . Furthermore, the illustrated order of blocks is illustrative only and the order of the blocks can change according to the present disclosure. Additional blocks can be added or fewer blocks may be utilized, without departing from this disclosure. The example method  70  can begin at block  701 . 
     At block  701 , also referring to  FIG. 18 , magnetic particles  330  and resin particles  322  are mixed together and then heat pressed to form the main body  320 . In this embodiment, the resin particles  322  are polyimide resin particles. 
     At block  702 , also referring to  FIG. 19 , a plate  10  for forming the middle plate  340  is provided. The main body  320  is adhered to a top face  11  of the plate  10 , which has a bottom face  12  opposite the top face  11 . The plate  10  can be made of glass or magnetic metal such as Invar. In this embodiment, the plate is made of Invar. 
     At block  703 , also referring to  FIG. 20 , the plate  10  together with the main body  320  is inverted. Then a photoresist coating  20  is applied to the bottom face  12  of the plate  10 . 
     At block  704 , also referring to  FIG. 21 , a photo mask  30  is brought over the photoresist coating  20  and a light irradiation is applied to the photoresist coating  20  through the photo mask  30  as indicated by arrows in  FIG. 21 . Accordingly, the photoresist coating  21  becomes a patterned coating  21 , as shown in  FIG. 22 . 
     At block  705 , also referring to  FIG. 23 , an etching is processed to the plate  10  to define the plurality of holes  341  therethrough to thereby obtain the middle plate  340 . 
     At block  706 , also referring to  FIG. 24 , the base  310  is provided, which defines the central rectangular opening  311  therein. The middle plate  340  is inverted again to have main body  320  at an upper side thereof. A bottom face of the middle plate  340  is adhered or soldered to the base  310 . 
     At block  707 , also referring to  FIG. 25 , laser beams  80  are applied to the main body  320  to define the plurality of groups of apertures  3211  therein to form the plurality of pixel patterns  321 . Thus, the evaporation mask  300  in accordance with the third embodiment of the present disclosure is obtained. 
     The embodiments shown and described above are only examples. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, including in particular the matters of shape, size and arrangement of parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims.