TWI849325B - Display module and manufacturing method thereof - Google Patents

Abstract

Disclosed is a method for manufacturing a display module. The method includes the steps of: providing a printed circuit board; arranging a plurality of Mini-LED chips on the printed circuit board; forming a cured transparent adhesive layer to completely cover the printed circuit board and the Mini-LED chips; forming a black matrix pattern on the cured transparent adhesive layer, wherein the black matrix pattern and the Mini-LED chips do not overlap in the vertical direction; disposing an optical glue layer on the black matrix pattern and the partially exposed surface of the cured transparent adhesive layer corresponding to the Mini-LED chips; and arranging a transparent cover on the optical adhesive layer.

Description

Display module and manufacturing method thereof

The present invention relates to a method for manufacturing a display module, and more particularly to a method for manufacturing a sub-millimeter light-emitting diode (Mini-LED) display module.

In the manufacturing process of general Mini-LED display modules, the black matrix (BM) process usually involves filling the gaps between sub-millimeter LED components by dispensing glue after the sub-millimeter LED components are attached to the printed circuit board. This can separate the sub-millimeter LED components to prevent adjacent sub-millimeter LED components from being interfered with by the light emitted by each other.

However, as the size of sub-millimeter LED components is getting smaller and smaller, the gaps between the sub-millimeter LED components are also getting smaller and smaller, making it increasingly difficult to fill the black matrix into the gaps between the sub-millimeter LED components by glue dispensing, resulting in a poor glue dispensing yield. As shown in FIG. 1 , the manufacturing process of the sub-millimeter LED display module 100 in the prior art mainly includes firstly attaching a plurality of sub-millimeter LED elements 104 to a printed circuit board 102, and then filling a black matrix 106 in the gaps between adjacent sub-millimeter LED elements 104 by dispensing glue, and then covering the sub-millimeter LED elements 104 and the black matrix 106 with transparent glue 108, and then bonding them to a transparent cover plate 112 by optical glue 110. As can be seen from FIG. 1 , when electronic components continue to shrink, the black matrix dispensing process will have the following defects. For example, in the first area A1, the amount of glue in the black matrix 106 is too much, resulting in the light-emitting surface S1 of the sub-millimeter LED element 104 being covered by the black matrix 106, and the light cannot be emitted or the light is greatly attenuated. In addition, in the second area A2, the distance between the adjacent sub-millimeter LED elements 104 is too large, so that the black matrix 106 cannot fill the first opening O1 and the second opening O2. In the third area A3, due to insufficient amount of glue of the black matrix 106, the adjacent sub-millimeter LED device 104 still has cross-talk problem. In the fourth area A4, due to the small opening of the sub-millimeter LED device 104, the glue of the black matrix 106 overflows and covers the light-emitting surface S1 of the sub-millimeter LED device 104. In the fifth area A5, the position of the black matrix 106 is offset, resulting in the side of the sub-millimeter LED device 104 not being covered by the black matrix 106, and the cross-talk problem occurs. The defects caused by the above-mentioned dispensing process may cause light beam crosstalk or optical noise to occur.

Representatively, these known technologies show the design and manufacturing of display modules. If the stacking structure and manufacturing method of the display module, as well as the above-mentioned application scenarios, are redesigned to be different from those of the users, its usage pattern can be changed and its application range can be increased, which is different from the old method. For example, under the conditions of considering the structure and improving the effects of beam crosstalk, the old method must be improved according to different configurations, and display modules with light-emitting surfaces of the same height must be manufactured respectively, so that each sub-millimeter light-emitting diode element can improve the accuracy of glue dispensing, reduce the overall production time, reduce the above-mentioned beam crosstalk, and make each sub-millimeter light-emitting diode element less likely to be offset. These topics are not specifically taught or disclosed in the above-mentioned reference materials.

Therefore, the present invention mainly provides a display module that can effectively optimize the overall display effect and improve the production yield.

In view of the above content, one aspect of the present disclosure is to provide a method for manufacturing a display module, comprising: providing a printed circuit board; disposing a plurality of sub-millimeter light-emitting diode elements on the printed circuit board; forming a cured transparent adhesive layer to completely cover the printed circuit board and the sub-millimeter light-emitting diode elements; forming a black matrix pattern on the cured transparent adhesive layer, wherein the black matrix pattern and the sub-millimeter light-emitting diode elements are misaligned in a vertical direction; disposing an optical adhesive layer on the black matrix pattern and a portion of the exposed surface of the cured transparent adhesive layer corresponding to the sub-millimeter light-emitting diode elements; and disposing a transparent cover plate on the optical adhesive layer.

According to one or more embodiments of the present disclosure, the step of forming the cured transparent adhesive layer is to first apply the transparent adhesive layer to a height greater than the height of the sub-millimeter LED elements, and then cure the transparent adhesive layer to form a flat surface.

According to one or more embodiments of the present disclosure, the step of forming the black matrix pattern is to first print a photosensitive ink layer on the cured transparent adhesive layer, and then remove the portion of the photosensitive ink layer corresponding to the sub-millimeter LED elements by a yellow light process.

According to one or more embodiments of the present disclosure, the portion of the photosensitive ink layer corresponding to the sub-millimeter LED elements is removed by etching.

Another aspect of the present disclosure is to provide a display module, comprising: a printed circuit board; a plurality of sub-millimeter light-emitting diode elements disposed on the printed circuit board; a cured transparent adhesive layer, completely covering the printed circuit board and the sub-millimeter light-emitting diode elements; a black matrix pattern, disposed on the cured transparent adhesive layer, wherein the black matrix pattern has a plurality of openings, and the openings respectively correspond to the sub-millimeter light-emitting diode elements; and an optical adhesive layer, attaching a transparent cover plate to the black matrix pattern and the sub-millimeter light-emitting diode elements.

According to one or more embodiments of the present disclosure, a top surface and all side surfaces of any of the sub-millimeter light-emitting diode components are covered by the cured transparent adhesive layer.

According to one or more embodiments of the present disclosure, the transmittance of the cured transparent adhesive layer is greater than 85%.

According to one or more embodiments of the present disclosure, the cured transparent adhesive layer has a flat surface, wherein the height difference of the flat surface is less than 10 μm.

According to one or more embodiments of the present disclosure, the difference between the height of the cured transparent adhesive layer and the height of any of the sub-millimeter LED elements is greater than or equal to 5 μm, but less than or equal to 15 μm.

According to one or more embodiments of the present disclosure, a horizontal distance between any side surface of any opening of the black matrix pattern and any corresponding sub-millimeter LED element is less than 10 μm.

In order to help the review committee members to have a deeper understanding of the purpose, shape, structural features and effects of the present invention, the following embodiments are provided with accompanying drawings for detailed description.

The following disclosure provides different embodiments or examples to implement different features of the subject matter provided. The specific examples of components and arrangements described below are for the purpose of simplifying the present disclosure and are not intended to be limiting; the size and shape of the components are not limited by the disclosed range or values, but may depend on the process conditions or required characteristics of the components. For example, cross-sectional views are used to describe the technical features of the present invention, and these cross-sectional views are idealized schematic views of embodiments. Therefore, it is foreseeable that the shapes of the diagrams will be different due to manufacturing processes and/or tolerances, and should not be limited thereto.

Furthermore, spatially relative terms, such as “below,” “under,” “lower than,” “above,” and “higher than,” are intended to easily describe the relationship between elements or features depicted in the diagrams; in addition, spatially relative terms include different directions of the components when in use or operation in addition to the directions depicted in the diagrams.

The following is a diagram illustrating the display module and its manufacturing method of the embodiment of the present invention. It should be particularly noted that in order to solve the problem of defects in the black matrix dot glue process caused by the continuous shrinkage of electronic components in the prior art, the embodiment of the present invention first forms a solidified transparent glue layer on the sub-millimeter light-emitting diode element, and then uses a yellow light process to make a black matrix pattern on the solidified transparent glue layer. In this way, it can be ensured that the opening size of the sub-millimeter light-emitting diode element is consistent and will not be offset. This point will be further explained in detail in the following content.

First, please refer to FIG. 2A to FIG. 2F , which illustrate a method for manufacturing a display module according to an embodiment of the present invention.

As shown in FIG2A , a plurality of sub-millimeter light emitting diode devices 204 are bonded to a printed circuit board 202. There is a certain distance between the plurality of sub-millimeter light emitting diode devices 204. In this embodiment, the printed circuit board 202 is, for example, a flexible printed circuit board, including a single-sided board, a double-sided board, or a multi-layer board.

Next, as shown in FIG2B , a transparent adhesive layer is coated on the printed circuit board 202, and completely covers the surface of the printed circuit board 202 and a plurality of sub-millimeter LED elements 204. Next, a curing step is performed to cause the transparent adhesive layer to undergo a curing reaction to form a cured transparent adhesive layer 206 having a flat surface with a height difference of less than 10 μm.

In this embodiment, when the transparent adhesive layer is applied, the transparent adhesive layer is made higher than all the plurality of sub-millimeter LED components 204, so that the cured transparent adhesive layer 206 can not only completely cover the surface of the printed circuit board 202 and the plurality of sub-millimeter LED components 204, but also completely cover the side surface of each sub-millimeter LED component 204. Please refer to FIG. 5 , in this step, the difference between the height of the cured transparent adhesive layer 206 and the height d3 of any sub-millimeter LED component 204 is greater than or equal to 5 μm, but less than or equal to 15 μm. In this way, by forming a cured transparent adhesive layer 206 having a height greater than any one millimeter LED element 204 and a flat surface, subsequent black matrix manufacturing processes can be performed and the yield can be ensured.

In addition, in this embodiment, the cured transparent adhesive layer 206 may be a light-cured or heat-cured transparent adhesive. The transmittance of the cured transparent adhesive layer 206 is greater than 85%.

Afterwards, referring to FIG. 2C , a black matrix process is performed on the flat surface of the cured transparent adhesive layer 206. Since the cured transparent adhesive layer 206 has a flat surface, it is convenient to print a photosensitive ink layer 208 with a uniform thickness thereon. In other embodiments, the photosensitive ink layer 208 can also be formed on the cured transparent adhesive layer 206 by other methods.

Then, a yellow light process is performed on the photosensitive ink layer 208 printed on the cured transparent adhesive layer 206. As shown in FIG2D, a photomask 250 and a light source 252 are used to expose the photosensitive ink layer 208. In this embodiment, the photomask 250 has a pattern to be transferred to the photosensitive ink layer 208, and this pattern can form an opening 210 of the same size above each sub-millimeter light-emitting diode element 204 (please refer to FIG2E), and the opening 210 will not shift. In addition, in this embodiment, the light source 252 can be a light source of ultraviolet light or other wavelengths. In this embodiment, the photosensitive ink layer 208 may be made of UV-curable ink or other photosensitive materials. When the portion of the photosensitive ink layer 208 other than the sub-millimeter LED element 204 is irradiated by light from the light source 252, a curing reaction occurs and the ink becomes hard. In other words, according to the design of the photomask 250, the portion of the photosensitive ink layer 208 opposite the sub-millimeter LED element 204 is not irradiated because the pattern on the photomask 250 blocks the light from the light source 252, and thus no curing reaction occurs.

Next, referring to FIG. 2E , after the exposure step is completed for the photosensitive ink layer 208, a developing step and/or etching step is continued for the photosensitive ink layer 208. In this embodiment, a suitable developer and/or etching solution can be selected to remove the portion of the photosensitive ink layer 208 that is not exposed to light in the above exposure step, that is, the portion of the photosensitive ink layer 208 that does not produce a curing reaction. In this way, the portion of each sub-millimeter light-emitting diode element 204 corresponding to the upper photosensitive ink layer 208 can be accurately removed, and finally a plurality of openings 210 are formed in the photosensitive ink layer 208 to form a patterned photosensitive ink layer 208a, and each opening 210 corresponds to each sub-millimeter light-emitting diode element 204 below. In this embodiment, the patterned photosensitive ink layer 208a is manufactured using a yellow light process. Even if the resolution requirement of the display is getting higher and higher, the manufacturing time will not be affected by the resolution. In addition to improving the productivity, the yield is also higher than the dispensing process. That is to say, with the trend of increasing resolution of the display, the yellow light process is more accurate than the dispensing process in manufacturing the patterned photosensitive ink layer 208a, and can ensure that the size of the opening 210 of each sub-millimeter LED element 204 is consistent and will not shift. In this way, the problems of the sub-millimeter LED element opening being too large, the sub-millimeter LED element opening being too small, the black matrix glue amount being too little, the black matrix glue amount being too much, or the black matrix position shifting generated by the dispensing process for manufacturing the patterned photosensitive ink layer 208a can be solved. In this embodiment, the diameter of each opening 210 from top to bottom is consistent. However, in another embodiment, each opening 210 is gradually contracted, that is, the diameter becomes smaller from bottom to top. In yet another embodiment, each opening 210 is gradually expanded, that is, the diameter becomes larger from bottom to top.

Please refer to FIG. 2E again. At this point, a patterned photosensitive ink layer 208a has been formed on the cured transparent adhesive layer 206, and the surface of the cured transparent adhesive layer 206 corresponding to each sub-millimeter LED element 204 is exposed through the opening 210 in the patterned photosensitive ink layer 208a, so that light from the sub-millimeter LED element 204 can pass through and subsequent processing can be performed.

2F, a transparent cover plate 214 is bonded to the patterned photosensitive ink layer 208a and the partially exposed surface of the cured transparent adhesive layer 206 corresponding to the sub-millimeter LED element 204 using an optical adhesive layer 212. Thus, the display module 200 is completed.

The structure of the display module 200 is further described below using FIG. 3 to FIG. 5 . FIG. 3 shows a display module according to an embodiment of the present invention. FIG. 4 shows a partially enlarged top view of the display module of FIG. 3 . FIG. 5 shows a partially enlarged cross-sectional view of the display module of FIG. 3 .

As shown in FIG3 , a display module 200 of an embodiment of the present invention is manufactured by the manufacturing method of the display module of FIG2A to FIG2E . In this embodiment, the display module 200 includes a printed circuit board 202, a plurality of sub-millimeter light-emitting diode elements 204, a cured transparent adhesive layer 206, a patterned photosensitive ink layer 208a, an optical adhesive layer 212, and a transparent cover plate 214. In addition, in this embodiment, the material of the patterned photosensitive ink layer 208a is chromium (Cr), so it can also be called a black matrix pattern. However, in other embodiments, the material of the patterned photosensitive ink layer 208a can also be selected from other materials with a light-shielding effect, such as red, green, blue, etc. color photoresists used for color filters.

Please refer to FIG. 3 again, the plurality of sub-millimeter light-emitting diode elements 204 are arranged on the printed circuit board 202. The cured transparent adhesive layer 206 completely covers the printed circuit board 202 and the sub-millimeter light-emitting diode elements 204. The patterned photosensitive ink layer 208a is arranged on the cured transparent adhesive layer 206. The patterned photosensitive ink layer 208a has a plurality of openings 210, and the openings 210 correspond to the sub-millimeter light-emitting diode elements 204 respectively. The optical adhesive layer 212 attaches the transparent cover plate 214 to the patterned photosensitive ink layer 208a and the partially exposed surface of the cured transparent adhesive layer 206 corresponding to the sub-millimeter light-emitting diode elements 204.

In addition, please refer to FIG. 3 and FIG. 4 at the same time. FIG. 4 is a partial enlarged top view of the display module of FIG. 3, which is used to illustrate the partial structure 220 of FIG. 1. As shown in FIG. 4, the portion outside the opening 210 is covered by the patterned photosensitive ink layer 208a to prevent light leakage and light interference between adjacent sub-millimeter light-emitting diode elements 204. Furthermore, looking down from the opening 210, a partial surface of the cured transparent adhesive layer 206 and the upper surface of a sub-millimeter light-emitting diode element 204 can be seen. In this embodiment, the opening 210 and the corresponding sub-millimeter light-emitting diode element 204 have a distance d1 in the width direction and a distance d2 in the length direction. Specifically, the distance d1 is the horizontal distance from the inner edge of the long side of the opening 210 to the outer edge of the long side of the corresponding sub-millimeter LED device 204 in the opening 210; the distance d2 is the horizontal distance from the inner edge of the short side of the opening 210 to the outer edge of the short side of the corresponding sub-millimeter LED device 204 in the opening 210. In this embodiment, the distance d1 is equal to the distance d2, and both are less than 10 μm.

In addition, please refer to FIG. 3 and FIG. 5 at the same time. FIG. 5 is a partial enlarged cross-sectional view of the display module of FIG. 3, which is also used to illustrate the partial structure 220 of FIG. 1. As shown in FIG. 5, the upper surface and all side surfaces of the sub-millimeter light-emitting diode element 204 disposed on the printed circuit board 202 are completely covered and encapsulated by the cured transparent adhesive layer 206, and the patterned photosensitive ink layer 208a covering the cured transparent adhesive layer 206 allows the light emitted by the sub-millimeter light-emitting diode element 204 to pass through the opening 210. In this embodiment, the cured transparent adhesive layer 206 and the sub-millimeter LED element 204 have a height difference d3, which is the vertical distance from the lower surface of the patterned photosensitive ink layer 208a to the upper surface of the sub-millimeter LED element 204. In this embodiment, the height difference d3 is greater than or equal to 5 μm, but less than or equal to 15 μm.

It should be particularly noted that in this embodiment, the height of the cured transparent adhesive layer 206 is greater than the height of any sub-millimeter light-emitting diode element 204. In this embodiment, the cured transparent adhesive layer 206 completely covers the upper surface and all side surfaces of any sub-millimeter light-emitting diode element 204. In this embodiment, the transmittance of the cured transparent adhesive layer is greater than 85%. In this embodiment, the cured transparent adhesive layer 206 has a flat surface, and the height difference of the flat surface is less than 10 μm.

In summary, the manufacturing process of Mini-LED display modules in the prior art is to fill the gaps between the sub-millimeter LED components by glue dispensing after the sub-millimeter LED components are bound on the printed circuit board. However, such a black matrix glue dispensing process does not have a good yield rate when the display resolution continues to increase. In contrast, the display module and the manufacturing method thereof proposed in the embodiment of the present invention is to first form a cured transparent adhesive layer on the sub-millimeter LED element after the sub-millimeter LED element is bound to the printed circuit board, and then use a yellow light process to make a black matrix pattern on the cured transparent adhesive layer. In this way, it can be ensured that the opening size of the sub-millimeter LED element is consistent and will not be offset, thereby improving the process yield.

The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

100: Sub-millimeter LED display module 102: Printed circuit board 104: Sub-millimeter LED element 106: Black matrix 108: Transparent adhesive 110: Optical adhesive 112: Transparent cover plate 200: Display module 202: Printed circuit board 204: Sub-millimeter LED element 206: Cured transparent adhesive layer 208: Photosensitive ink layer 208a: Figure Photosensitive ink layer 210: opening 212: optical adhesive layer 214: transparent cover plate 220: local structure 250: photomask 252: light source d1: spacing d2: spacing d3: height difference A1: first area A2: second area A3: third area A4: fourth area A5: fifth area S1: luminous surface O1: first opening O2: second opening

In order to make the above and other purposes, features, advantages and embodiments of the present invention more clearly understandable, the attached drawings are described as follows: FIG. 1 shows a display module of the prior art. FIG. 2A to FIG. 2F show a method for manufacturing a display module of an embodiment of the present invention. FIG. 3 shows a display module of an embodiment of the present invention. FIG. 4 shows a partially enlarged top view of the display module of FIG. 3. FIG. 5 shows a partially enlarged cross-sectional view of the display module of FIG. 3.

According to conventional operation methods, various features and components in the figure are not drawn according to the actual scale, and the drawing method is to present the specific features and components related to the present invention in the best way. In addition, between different figures, the same or similar element symbols are used to refer to similar elements and components.

200: Display module

202: Printed circuit board

204: Sub-millimeter light-emitting diode element

206: Cured transparent adhesive layer

208a: Patterned photosensitive ink layer

210: Open mouth

212: Optical glue layer

214: Translucent cover

220: Local structure

Claims (3)

A method for manufacturing a display module comprises: providing a printed circuit board; then, disposing a plurality of sub-millimeter light-emitting diode components on the printed circuit board; then, forming a cured transparent adhesive layer to completely cover the exposed surface of the printed circuit board where the sub-millimeter light-emitting diode components are not disposed and the sub-millimeter light-emitting diode components, so that an upper surface and all side surfaces of any sub-millimeter light-emitting diode component are covered by the cured transparent adhesive layer; forming a black matrix pattern on the cured transparent adhesive layer , wherein the black matrix pattern and the sub-millimeter light-emitting diode elements are misaligned in the vertical direction; an optical adhesive layer is disposed on the black matrix pattern and the exposed surface of the cured transparent adhesive layer corresponding to the sub-millimeter light-emitting diode elements; and a transparent cover plate is disposed on the optical adhesive layer; wherein the step of forming the black matrix pattern is to first print a photosensitive ink layer on the cured transparent adhesive layer, and remove the portion of the photosensitive ink layer corresponding to the sub-millimeter light-emitting diode elements by a yellow light process. The manufacturing method of the display module as described in claim 1, wherein the step of forming the cured transparent adhesive layer is to first apply the transparent adhesive layer so that its height is greater than the height of the sub-millimeter light-emitting diode elements, and then cure the transparent adhesive layer to form a flat surface. A method for manufacturing a display module as described in claim 1, wherein the portion of the photosensitive ink layer corresponding to the sub-millimeter light-emitting diode elements is removed by etching.

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