Patent Publication Number: US-2023154940-A1

Title: Manufacturing method of mini-led backlight plate and mini-led backlight plate

Description:
BACKGROUND OF INVENTION 
     Field of Invention 
     The present application relates to the field of display technology and particularly to a manufacturing method of a mini light emitting diode (mini-LED) backlight plate and the mini-LED backlight plate. 
     Description of Prior Art 
     In order to ensure working stability of thin film transistor devices in manufacturing of mini light emitting diode (mini-LED) backlight plates, and to maximize light utilization and optical quality as much as possible, there is a process of passivation coating layers, wherein a thickness of the passivation coating layers is less than 30 um, and reflectivity of which is greater than 80%. In order to enable the passivation coating layers to form patterns at set positions, it is necessary to dispose metal mark objects on surfaces of substrates for alignment by exposure machines. When the set metal mark objects are used for alignment by the exposure machines, light of light sources penetrates the passivation coating layers and is reflected on the metal mark objects, and then is inputted to charge-coupled device (CCD) lenses with a function of detecting reflected light. Therefore, the alignment process of the passivation coating layers by the exposure machines is completed, so that the passivation coating layers can form corresponding patterns according to the set positions and sizes. One of current formation methods of the passivation coating layer is to fully coat the passivation coating layers on surfaces of the substrates. Regarding passivation coating materials with high reflectivity, most light from light sources is directly reflected after passing through the passivation coating layers, and it is difficult for the light to reach the surfaces of the metal mark objects, so the exposure machines cannot be aligned accurately, resulting in the passivation coating layers being unable to form the set patterns. In addition, after the process of passivation coating layers is completed, and corresponding size is cut in sequence, due to a relatively high film thickness of the passivation coating layers and inherent material characteristics, the passivation coating layers are prone to be jagged in the cutting regions during cutting. In severe cases, it will cause conditions of edge cracking and peeling off. Another one of the current formation methods of the passivation coating layers is not coating the passivation coating layers on entire edges of the surfaces of the substrates where the metal mark objects are disposed, which is conducive to the CCD lens reading the positions of the metal mark objects for accurate alignment by the exposure machines. However, edge regions of the substrates are wasted, and maximum utilization rate of the substrates cannot be realized, which causes production cost to rise sharply. 
     A technical problem is that in another one of the current formation methods of the passivation coating layers, although not coating the passivation coating layers on the entire edge of the surfaces of the substrates where the metal mark objects are disposed is conducive to the CCD lens reading the positions of the metal mark objects for accurate alignment by the exposure machines, edge regions of the substrates are wasted, and maximum utilization rate of the substrates cannot be realized. This can cause production cost to rise sharply. 
     SUMMARY OF INVENTION 
     Embodiments of the present application provide a manufacturing method of a mini light emitting diode (mini-LED) backlight plate and the mini-LED backlight plate, which allows a passivation coating layer with a set pattern to be formed, while a maximum utilization rate of a substrate is realized, and production cost is reduced. 
     One embodiment of the present application provides a manufacturing method of a mini light emitting diode (mini-LED) backlight plate, including following steps: 
     providing a substrate, defining at least one display region on a surface of a side of the substrate, other region on the surface of the side of the substrate except for the at least one display region is a non-display region, defining at least one mark region in the non-display region, and disposing a metal mark objects in the mark region, 
     covering the surface of the side of the substrate by a mask, covering the at least one display region and part of the non-display region on the surface of the side of the substrate by the mask to allow the at least one mark region to be exposed outside, and adopting a hydrophilic material to form a layer of a thin film on the at least one mark region; 
     removing the mask; and coating a hydrophobic material on the entire surface of the side of the substrate to form a passivation coating layer. 
     One embodiment of the present application further provides the manufacturing method of the mini-LED backlight plate, including following steps: 
     providing a substrate, defining a plurality of display regions on a surface of a side of the substrate, wherein other region on the surface of the side of the substrate except for the plurality of display regions is a non-display region, defining a plurality of cutting regions separating any two of the adjacent display regions in the non-display region; 
     covering the surface of the side of the substrate by a mask, covering the plurality of display regions and part of the non-display region on the surface of the side of the substrate by the mask to allow the plurality of cutting regions to be exposed outside, and adopting a hydrophilic material to form a layer of a thin film on the plurality of cutting regions; 
     removing the mask; coating a hydrophobic material on the entire surface of the side of the substrate to form a passivation coating layer; and 
     cutting the substrate along the plurality of cutting regions to form a sheet of a backlight plate. 
     One embodiment further provides a mini-LED backlight plate manufactured by adopting the aforesaid manufacturing method. 
     In the manufacturing method of the mini-LED backlight plate of the embodiments of the present application, other regions except the at least one mark region on the surface of the side of the substrate are covered by covering the mask on the surface of the substrate, the hydrophilic material is adopted to form the layer of the thin film on the at least one mark region exposed outside, the mask is removed, and the hydrophobic passivation coating layer is coated on the entire surface of the side of the substrate. Because the hydrophilic film formed on the at least one mark region makes it difficult for the hydrophobic passivation coating layer to form a film during coating, thereby exposing the metal mark objects, the exposure machines can align accurately, and the passivation coating layer of the set pattern is allowed to be formed. Meanwhile, the surface of the substrate can be coated with the passivation coating layer in the other regions except the at least one mark region, which can realize the maximum utilization rate of the substrate and reduce production cost. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       To more clearly illustrate the technical solutions of the embodiments of the present application, the required accompanying figures for description of embodiments is described in brief as follow. Obviously, the accompanying figures described below are only part of the embodiments of the present application, from which figures those skilled in the art can derive further figures without making any inventive efforts. 
         FIG.  1    is a flowchart of a manufacturing method of a mini light emitting diode (mini-LED) backlight plate provided by one embodiment of the present application. 
         FIG.  2    is a first operation process chart provided by one embodiment of the present application. 
         FIG.  3    is a structural schematic diagram of the mini-LED backlight plate provided by one embodiment of the present application. 
         FIG.  4    is a flowchart of forming a structure of a driving circuit provided by one embodiment of the present application. 
         FIG.  5    is a second operation process chart provided by one embodiment of the present application. 
         FIG.  6    is a third operation process chart provided by one embodiment of the present application. 
         FIG.  7    is a fourth operation process chart provided by one embodiment of the present application. 
         FIG.  8    is a fifth operation process chart provided by one embodiment of the present application. 
         FIG.  9    is a sixth operation process chart provided by one embodiment of the present application. 
         FIG.  10    is a seventh operation process chart provided by one embodiment of the present application. 
         FIG.  11    is an eighth operation process chart provided by one embodiment of the present application. 
         FIG.  12    is a ninth operation process chart provided by one embodiment of the present application. 
         FIG.  13    is a tenth operation process chart provided by one embodiment of the present application. 
         FIG.  14    is an eleventh operation process chart provided by one embodiment of the present application. 
         FIG.  15    is a flowchart of another manufacturing method of the mini-LED backlight plate provided by one embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The technical solutions in the embodiments of the present application are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but are not all embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts are within the scope of the present application. 
     Please refer to  FIGS.  1 - 14   .  FIG.  1    is a flowchart of a manufacturing method of a mini light emitting diode (mini-LED) backlight plate provided by one embodiment of the present application.  FIG.  2    is a first operation process chart provided by one embodiment of the present application.  FIG.  3    is a structural schematic diagram of the mini-LED backlight plate provided by one embodiment of the present application.  FIG.  4    is a flowchart of forming a structure of a driving circuit provided by one embodiment of the present application.  FIG.  5    is a second operation process chart provided by one embodiment of the present application.  FIG.  6    is a third operation process chart provided by one embodiment of the present application.  FIG.  7    is a fourth operation process chart provided by one embodiment of the present application.  FIG.  8    is a fifth operation process chart provided by one embodiment of the present application.  FIG.  9    is a sixth operation process chart provided by one embodiment of the present application.  FIG.  10    is a seventh operation process chart provided by one embodiment of the present application.  FIG.  11    is an eighth operation process chart provided by one embodiment of the present application.  FIG.  12    is a ninth operation process chart provided by one embodiment of the present application.  FIG.  13    is a tenth operation process chart provided by one embodiment of the present application.  FIG.  14    is an eleventh operation process chart provided by one embodiment of the present application. In one embodiment of the present application, the manufacturing method of the mini-LED backlight plate includes following steps. 
     Step  10 : as illustrated in  FIG.  2   , providing a substrate  100 , defining a plurality of display regions  110  arranged in a rectangular array manner on a surface of a side of the substrate  100 , wherein other region on the surface of the side of the substrate  100  except for the plurality of display regions  110  is a non-display region  120 ; defining a plurality of mark regions  130  in the non-display region  120 ; disposing the plurality of mark regions  130  corresponding to the plurality of display regions  110  one-to-one; disposing metal mark objects  140  in the mark regions  130 ; and further defining a plurality of cutting regions  150  separating any two adjacent display regions  110  in the non-display region  120 . 
     In the step  10 , the substrate  100  can be a glass substrate. It should be understood that the substrate  100  can also be made of other suitable rigid or flexible materials according to application requirements. The display region  110  is configured to dispose the driving circuit and light emitting devices to provide a display function. The display region  110  is preferably disposed as a plurality of display regions  110  arranged in a rectangular array manner, thereby being conducive to manufacturing a plurality of backlight plates on the substrate  100  to improve production efficiency. The plurality of mark regions  130  are disposed corresponding to the plurality of display regions one-to-one. The metal mark objects  140  are disposed in the mark regions  130 . By using the metal mark objects  140  for accurate alignment by an exposure machine, passivation coating layer of a set pattern is formed. After the backlight plate is completely manufactured, it can be cut into a plurality of small pieces along the plurality of cutting regions  150 . It can be understood that only one display region  110  and one corresponding mark region  130  are also allowed to be disposed on the substrate  100 . At this time, the backlight plate does not need to be cut into small the pieces after the manufacturing of the backlight plate is completed, so there is no need to divide the cutting regions  150  on one side of the surface of the substrate  100 . 
     Step  20 : forming a structure of a driving circuit  200  on the display region of the substrate  100  as illustrated in  FIG.  3   . 
     The driving circuit  200  includes a gate electrode  210 , a first electrode  220 , a second electrode  230 , a third electrode  270 , source and drain electrodes  240 , an active layer  250 , and a first binding electrode  260 . The gate electrode  210  and the first electrode  220  are disposed on a same layer. The gate electrode  210 , the source and drain electrodes  240 , and the active layer  250  compose a thin film transistor. The first electrode  220 , the second electrode  230 , and the third electrode  270  are located on a side of the thin film transistor. The first binding electrode  260  is located on another side of the thin film transistor. The second electrode  230  is electrically connected to the first electrode  220 . The third electrode  270  is electrically connected to the second electrode  230 . The third electrode  270  is configured to be electrically connected to a chip on film. The first binding electrode  260  is configured to be electrically connected to a light emitting diode. 
     In some embodiments, as illustrated in  FIG.  4   , steps of forming the structure of the driving circuit  200  on the display region of the substrate  100  includes the following. 
     Step  21 : forming a gate electrode  210  and a first electrode  220  on the substrate  100 . 
     Optionally, as illustrated in  FIGS.  5  and  6   , in the step  21 , a first conductive layer  300  is formed on the substrate  100 , and a patterning process is performed on the first conductive layer  300  to obtain the gate electrode  210  and the first electrode  220  disposed on the same layer. 
     Specifically, by forming the entire surface of the first conductive layer  300  on the substrate  100 , forming the entire surface of the photoresist layer covering the first conductive layer  300 , using a photomask to expose the photoresist layer, using a developer solution to develop the photoresist layer, and etching the first conductive layer  300  that is not covered by the photoresist layer to remove the remaining photoresist layer, the gate electrode  210  and the first electrode  220  are obtained. 
     Step  22 : forming the second electrode  230 , the source and drain electrodes  240 , the active layer  250 , and the first binding electrode  260 , wherein the second electrode  230  is electrically connected to the first electrode  220 . 
     Optionally, as illustrated in  FIGS.  7 - 10   , in the step  22 , a first insulation layer  400  covering the gate electrode  210 , the first electrode  220 , and the substrate  100  is formed; a semiconductor layer  500  is formed on a side of the first insulation layer  400  away from the substrate  100 ; a first via hole  280  penetrating the first insulation layer  400  and the semiconductor layer  500  and communicating with the first electrode  220  is formed; a second conductive layer  600  is formed in the first via hole  280  and on the semiconductor layer  500 ; a patterning process is performed on the second conductive layer  600  and the semiconductor layer  500 ; the second electrode  230 , the source and drain electrodes  240 , the active layer  250 , and the first binding electrode  260  are obtained; and the second electrode  230  is electrically connected to the first electrode  220  through the first via hole  280 . 
     Specifically, a chemical vapor deposition manner is used to form the first insulation layer  400  covering the gate electrode  210 , the first electrode  220 , and the substrate  100 . The first insulation layer  400  is a gate insulation layer. Then, amorphous silicon layer  510  covering the first insulation layer  400  and an n-type doped amorphous silicon layer  520  are sequentially formed. An entire surface of a photoresist layer is formed on the n-type doped amorphous silicon layer  520 , and the photoresist layer is exposed by using a photomask. After a developing process of a developer solution, the n-type doped amorphous silicon layer  520 , the amorphous silicon layer  510 , and the first insulation layer  400  corresponding to the first electrode  220  are etched to form the first via hole  280  penetrating the first insulation layer  400 , the n-type doped amorphous silicon layer  520 , and the amorphous silicon layer  510 . Sputtering deposition manner is adopted to form an entire surface of the second conductive layer  600  in the first via hole  280  and on the n-type doped amorphous silicon layer  520 . The entire surface of the photoresist layer is formed on the second conductive layer  600 . A halftone grayscale mask plate is adopted to expose the photoresist layer to define a photoresist completely removed region, a photoresist semi-remained region, and a photoresist fully remained region. After a photoresist of the photoresist completely removed region is processed by the developer solution, the second conductive layer  600 , the amorphous silicon layer  510 , and the n-type doped amorphous silicon layer  520  are etched, and the second electrode  230  and the first binding electrode  260  are obtained. The second electrode  230  is electrically connected to the first electrode  220  through the first via hole  280 . After a photoresist of the photoresist semi-remained region is processed by the developer solution, the n-type doped amorphous silicon layer  520  and the second conductive layer  600  of the photoresist semi-remained region are etched, and the source and drain electrodes  240  and the active layer  250  are obtained. The source and drain electrodes  240  are disposed corresponding to the active layer  250  and are electrically connected to the active layer  250 . The photoresist layer of the photoresist fully remained region is removed. 
     Step  23 : forming a third electrode  270 , wherein the third electrode  270  is electrically connected to the second electrode  230 . 
     Optionally, as illustrated in  FIGS.  11 - 13   , in the step  23 , a second insulation layer  700  covering the first binding electrode  260 , the second electrode  230 , the source and drain electrodes  240 , the active layer  250 , and the first insulation layer  400  is formed; a second via hole  290  penetrating the second insulation layer  700  and communicating with the second electrode  230  is formed; a third via hole  295  penetrating the second insulation layer  700  and communicating with the first binding electrode  260  is formed; a third conductive layer  800  is formed in the second via hole  290  and on the second insulation layer  700 ; a patterning process is performed on the third conductive layer  800  to obtain a third electrode  270 ; and the third electrode  270  is electrically connected to the second electrode  230  through the second via hole  290 . 
     Specifically, an entire surface of the third conductive layer  800  is formed in the second via hole  290 , in the third via hole  295 , and on the second insulation layer  700 ; an entire surface of a photoresist layer is formed on the third conductive layer  800 ; and after exposing the photoresist layer by using a photomask and developing by the developer solution, the third conductive layer  800  is etched to remove a remaining photoresist layer to allow the first binding electrode  260  to be exposed to obtain the third electrode  270 . A manufacturing material of the third conductive layer  800  is indium tin oxide. The third electrode  270  is electrically connected to the second electrode  230  through the second via hole  290 . 
     It should be understood that in this method, the substrate  100  provided in the step  10  can already have included the driving circuit  200  disposed in the display region  110 , but does not need to include processing steps of specially forming the driving circuit  200  on the substrate  100 . 
     Step  30 : covering the surface of the side of the substrate  100  by a mask  900 , using the mask  900  to cover the plurality of display regions  110  and part of the non-display region  120  on the surface of the side of the substrate  100  to allow the plurality of mark regions  130  and the plurality of cutting regions  150  to be exposed outside, and adopting a hydrophilic material to form a layer of the thin film on the plurality of mark regions  130  and the plurality of cutting regions  150 , as illustrated in  FIG.  14   . 
     In the step  30 , the mask  900  is configured to shield one side of the substrate  100  to remove other regions of the plurality of mark regions  130  and the plurality of cutting regions  150 , and to expose the plurality of mark regions  130  and the plurality of cutting regions  150 , which is conducive to the hydrophilic material forming the thin film on the plurality of mark regions  130  and the plurality of cutting regions  150 . Meanwhile, the hydrophilic material will not be coated on other regions to affect the formation of the passivation coating layer on the other regions. 
     In some embodiments, the hydrophilic material is poly(methyl methacrylate). 
     In some embodiments, a steam spray manner or a spraying manner is adopted to allow the hydrophilic material to form the thin film on the plurality of mark regions  130  and the plurality of cutting regions  150 . 
     Step  40 : removing the mask  900  and coating a hydrophobic material on the entire surface of the side of the substrate  100  to form a passivation coating layer. 
     In the step  40 , after the mask  900  is removed, when the hydrophobic passivation coating layer is coated on the entire surface of the side of the substrate  100 , as the hydrophilic film is formed on the plurality of mark regions  130  and the plurality of the cutting regions  150  of one side of the substrate  100 , and the hydrophobic passivation coating layer cannot form a film on the plurality of mark regions  130  and the plurality of cutting regions  150 , the metal mark objects  140  and the plurality of cutting regions  150  on the plurality of mark regions  130  are exposed, and the passivation coating layer can be formed on the other region on the surface of the substrate  100  except the plurality of mark regions  130  and the plurality of cutting regions  150 . 
     Step  50 : cutting the substrate  100  along the plurality of cutting regions  150  to form a sheet of a backlight plate. 
     In the step  50 , because the hydrophobic passivation coating layer cannot form a film on the cutting regions  150 , the plurality of cutting regions  150  are exposed, which allows cutting to the passivation coating layer to be prevented, and situations of cracking and peeling off occurring on the passivation coating layer on the edge of the backlight plate will not occur. It should be understood that if only one display region  110  is disposed on the surface of the substrate  100 , there is no need to cut the substrate  100 . 
     In some embodiments, a material of the hydrophobic passivation coating layer is WPR. Between the steps of removing the mask  900  and coating the hydrophobic material on the entire surface of the side of the substrate  100  to form the passivation coating layer and cutting the substrate along the plurality of cutting regions  150  to form the sheet of the backlight plate, the following step is further included: performing a first baking process, an exposure process, a development process, and a second baking process on the substrate  100  sequentially. 
     Wherein, WPR is a positive photoresist material or a negative photoresist material from JSR Micro, Inc. (Sunnyvale, Calif.) with a trademark of WPR. Photoresist materials of WPR series are a positive photoresist material or a negative photoresist material having a low curing temperature and can be formed from a thickness of about 5 microns to about 20 microns. In a red-green-blue (RGB) negative color resist process of a WPR material, a pattern can be formed through processes of coating, exposure, and development, which can be well linked to factories of thin film transistor liquid crystal displays (TFT-LCDs). Furthermore, it is not necessary to cut the glass substrate into small pieces before performing the process of coating the passivation coating layer, which can greatly improve production efficiency. 
     Preferably, a thickness of the passivation coating layer is less than 10 μm. The passivation coating layer with a smaller thickness can reduce costs, and it has a relatively high reflectivity of more than 80% at a same time, which can improve optical quality of the backlight. 
     In the manufacturing method of the mini-LED backlight plate of the embodiments of the present application, other region except the plurality of mark regions  130  on the surface of the side of the substrate  100  is covered by covering the mask  900  on the surface of the substrate  100 , the hydrophilic material is adopted to form the layer of the thin film on the plurality of mark region  130  exposed outside, the mask  900  is removed, and the hydrophobic passivation coating layer is coated on the entire surface of the side of the substrate  100 . Because the hydrophilic film formed on the plurality of mark regions  130  makes it difficult for the hydrophobic passivation coating layer to form a film during coating, thereby exposing the metal mark objects  140 , the exposure machines can align accurately, and the passivation coating layer of the set pattern is allowed to be formed. Meanwhile, the surface of the substrate  100  can be coated with the passivation coating layer in the other regions except the plurality of mark regions  130 , which can realize the maximum utilization rate of the substrate  100  and reduce production cost. 
     Please refer to  FIG.  15   .  FIG.  15    is a flowchart of another manufacturing method of the mini-LED backlight plate provided by one embodiment of the present application. In one embodiment of the present application, the manufacturing method of the mini-LED backlight plate includes following steps. 
     Step  10 ′: with reference to  FIG.  2   , providing the substrate  100 , defining a plurality of display regions  110  on a surface of a side of the substrate  100 , wherein, other region on the surface of the side of the substrate  100  except for the plurality of display regions  110  is a non-display region  120 ; and defining a plurality of cutting regions  150  separating any two adjacent display regions  110  in the non-display region  120 . 
     Step  20 ′: with reference to  FIG.  14   , covering the surface of the side of the substrate  100  by a mask  900 , using the mask  900  to cover the plurality of display regions  110  and part of the non-display region  120  on the surface of the side of the substrate  100  to allow the plurality of cutting regions  150  to be exposed outside, and adopting a hydrophilic material to form a layer of the thin film on the plurality of cutting regions  150 . 
     Step  30 ′: removing the mask  90  and coating a hydrophobic material on the entire surface of the side of the substrate  100  to form a passivation coating layer. 
     Step  40 ′: cutting the substrate  100  along the plurality of cutting regions  150  to form a sheet of a backlight plate. 
     In the manufacturing method of the mini-LED backlight plate of the embodiments of the present application, because the hydrophobic passivation coating layer cannot form a film on the cutting regions  150 , the plurality of cutting regions  150  are exposed, which allows cutting to the passivation coating layer during cutting the substrate  100  to form the sheet of a backlight plate to be prevented, and situations of cracking and peeling off occurring on the passivation coating layer on the edge of the backlight plate will not occur. 
     In some embodiments, the hydrophilic material is poly(methyl methacrylate). 
     In some embodiments, a steam spray manner or a spraying manner is adopted to allow the hydrophilic material to form the thin film on the plurality of cutting regions  150 . 
     In some embodiments, in the step  10 ′, a plurality of mark regions  130  are further defined in the non-display region  120 , the plurality of mark regions  130  are disposed corresponding to the plurality of display regions  110  one-to-one, and metal mark objects  140  are disposed in the mark regions  130 . In the step  20 ′, the mask covers the plurality of display regions  110  and part of the non-display region  120  on the surface of the side of the substrate  100  to allow the plurality of mark regions  130  and the plurality of cutting regions  150  to be exposed outside, and a hydrophilic material is adopted to form a layer of the thin film on the plurality of mark regions  130  and the plurality of cutting regions  150 . 
     In some embodiments, a material of the hydrophobic passivation coating layer is WPR. Between the step  30 ′ and the step  40 ′, the following step is further included: performing a first baking process, an exposure process, a development process, and a second baking process on the substrate  100  sequentially. 
     One embodiment further provides a mini-LED backlight plate manufactured by adopting the aforesaid manufacturing method. 
     Detailed description of the manufacturing method of the mini-LED backlight plate and the mini-LED backlight plate provided by the embodiments of the present application is described above. The principle and implementation manner of present application are described herein with reference to specific embodiments. The foregoing descriptions of the embodiments are merely used for better understanding of the present application. Meanwhile, for a person of ordinary skill in the art can make variations and modifications to the specific implementation manner and application scope according to the idea of this application. In summary, contents of the specification shall not be construed as a limitation to this application.