A display screen

Abstract

The utility model discloses a display screen, including a PCB board and a light-emitting chip welded on the PCB board, wherein the light-emitting chip is distributed in a Bayer array, and the side of the light-emitting chip that is not in contact with the PCB board is sealed by a sealing layer; the surface of the PCB board close to the light-emitting chip is sequentially covered with a first solder resist ink layer and a second solder resist ink layer by a rolling coating process, wherein the first solder resist ink layer and the second solder resist ink layer cover positions in the PCB board that do not require welding; the second solder resist ink layer covers the surface of the first solder resist ink layer, and the second solder resist ink layer is made of a transparent or translucent material. The present application forms a second solder resist ink layer with a protective function on the first solder resist ink layer, wherein the second solder resist ink layer is made of a transparent or translucent material and is coated on the first solder resist ink layer, thereby preventing the first solder resist ink layer from being corroded by a developer, improving the stability of the first solder resist ink layer, ensuring the stability of the welding position, and preventing the display screen from being distorted.

Description

Technical Field

[0001] The utility model relates to the technical field of display screen structures, in particular to a display screen. Background Art

[0002] At present, after the matt black solder mask ink on the PCB is made into a display screen, when the display screen is lit, the display screen will show different colors from different angles such as the front, side, top, and bottom, resulting in a flowery screen or a yin-yang screen. This is because during the exposure and development process after the matt black ink is applied, the developer will corrode the ink, causing the matt black ink to deform, and then the subsequent welding position will deform, resulting in a flowery screen or a yin-yang screen defect on the final display screen.

[0003] In order to solve the screen flower problem in the prior art, screen printing ink is usually used to form an ink layer on the PCB board. The ink is applied by screen printing, which helps to control the ink thickness within 10-20 μm By controlling the ink thickness and thickness range, the ink layer is ensured to remain stable in the subsequent exposure and development process, thereby reducing screen defects. However, simply controlling the ink thickness does not change the structure and processing procedures of the PCB board, and cannot completely eliminate screen defects, which affects the performance stability of the final product. Utility Model Content

[0004] In view of this, the present application aims to solve the problems in the related art to at least a certain extent. One of the purposes of the present application is to provide a display screen, by forming a second solder resist ink layer with a protective function on the first solder resist ink layer, the second solder resist ink layer is a transparent or translucent material, and is coated on the first solder resist ink layer. It can prevent the first solder resist ink layer from being corroded by the developer, improve the stability of the first solder resist ink layer, ensure the stability of the welding position, and avoid screen distortion of the display screen.

[0005] A display screen comprises a PCB board and a light-emitting chip welded on the PCB board, wherein the light-emitting chips are distributed in a Bayer array, and the side of the light-emitting chip that is not in contact with the PCB board is sealed by a sealing layer;

[0006] The surface of the PCB board close to the light-emitting chip is sequentially covered with a first solder resist ink layer and a second solder resist ink layer through a roll coating process, and the first solder resist ink layer and the second solder resist ink layer cover positions on the PCB board where no welding is required; the second solder resist ink layer covers the surface of the first solder resist ink layer, and the second solder resist ink layer is made of a transparent or translucent material.

[0007] Furthermore, the surface roughness of the second solder resist ink layer after exposure and development is 0.1-12.5 μm.

[0008] Furthermore, the transparency of the second solder resist ink layer after exposure and development is 30%-90%.

[0009] Furthermore, the thickness of the first solder resist ink layer is 10-40 μm, and the thickness of the second solder resist ink layer is 5-40 μm.

[0010] Furthermore, the surface of the PCB board is provided with a first circuit area, a second circuit area and a non-circuit area, and the first solder resist ink layer has different thicknesses in the first circuit area, the second circuit area and the non-circuit area;

[0011] The first circuit region is a region in the circuit pattern whose cross-sectional area is smaller than a first threshold, and the second circuit region is a region in the circuit pattern whose cross-sectional area is greater than or equal to the first threshold.

[0012] Furthermore, the thickness of the first solder resist ink layer on the first circuit area is 5-15 μm; the thickness of the first solder resist ink layer on the second circuit area is 5-20 μm; and the thickness of the first solder resist ink layer on the non-circuit area is 15-30 μm.

[0013] Furthermore, the thickness of the second solder resist ink layer on the first circuit area is 10-20 μm; the thickness of the second solder resist ink layer on the second circuit area is 10-20 μm; and the thickness of the second solder resist ink layer on the non-circuit area is 20-45 μm.

[0014] Furthermore, a first pad is formed in an area of ​​the PCB surface not coated with the first solder resist ink layer and the second solder resist ink layer, a second pad is provided in the light emitting chip, and the first pad and the second pad are connected.

[0015] Furthermore, when the light-emitting chip is mounted upright in the PCB board, the first pad and the second pad are connected via a wire; when the light-emitting chip is flipped in the PCB board, the first pad and the second pad are directly connected.

[0016] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art: the display screen of the present application includes a PCB board and a light-emitting chip soldered on the PCB board, the light-emitting chips are distributed in a Bayer array, and the side of the light-emitting chip that is not in contact with the PCB board is sealed by a sealing layer; the surface of the PCB board close to the light-emitting chip is sequentially covered with a first solder resist ink layer and a second solder resist ink layer by a roll coating process, the first solder resist ink layer and the second solder resist ink layer cover positions on the PCB board that do not require welding; the second solder resist ink layer covers the surface of the first solder resist ink layer, and the second solder resist ink layer is made of a transparent or translucent material. In the present application, the first solder resist ink layer and the second solder resist ink layer are both formed by a roll coating process, which can accurately control the thickness of the solder resist ink layer and reduce the range of the solder resist ink layer; and through two roll coating processes, the thickness range of the overall solder resist ink layer can be reduced; at the same time, in the present application, the first solder resist ink layer is a conventional matte black ink or other conventionally used solder resist inks, and the second solder resist ink layer is a transparent material or a translucent material. The second solder resist ink layer covers the first solder resist ink layer. During the development process, the second solder resist ink layer exists as a protective layer on the surface of the first solder resist ink layer, which can prevent the first solder resist ink layer from being corroded by the developer, thereby improving the stability of the first solder resist ink layer, ensuring the stability of the welding position, and avoiding display screen distortion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] In the attached figure:

[0020] Figure 1 This is a schematic diagram of the PCB board structure in this application;

[0021] Figure 2 It is a schematic diagram of the top-mounting and flip-mounting when the light-emitting chip is packaged through the SMD process;

[0022] Figure 3 It is a schematic diagram of the top-mounting and flip-mounting when the light-emitting chip is packaged through the IMD process;

[0023] Figure 4 The diagrams are the top-mounted and flip-mounted diagrams when the light-emitting chip is packaged through the COB process.

[0024] Reference numerals:

[0025] 11. PCB board; 12. Circuit pattern; 13. First solder resist ink layer; 14. Second solder resist ink layer; 21. Light emitting chip; 22. First solder pad; 23. Second solder pad; 24. Wire; 25. Sealing layer; 26. Driver IC. DETAILED DESCRIPTION

[0026] In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present application are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the mechanism or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present application.

[0027] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0028] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, mechanisms, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0029] Example 1

[0030] like Figure 1 As shown, a display screen proposed in the present application includes a PCB board 11 and a light-emitting chip 21 welded on the PCB board 11, wherein the light-emitting chip 21 is distributed in a Bayer array, and the side of the light-emitting chip 21 that does not abut against the PCB board 11 is sealed by a sealing layer 25; the surface of the PCB board 11 close to the light-emitting chip 21 is sequentially covered with a first solder resist ink layer 13 and a second solder resist ink layer 14 by a roll coating process, wherein the first solder resist ink layer 13 and the second solder resist ink layer 14 cover positions in the PCB board 11 where no welding is required; the second solder resist ink layer 14 covers the surface of the first solder resist ink layer 13, and the second solder resist ink layer 14 is made of a transparent or translucent material. A circuit pattern 12 is pre-formed on the PCB board 11.

[0031] In the present application, the first solder resist ink layer and the second solder resist ink layer are both formed by a roll coating process, which can accurately control the thickness of the solder resist ink layer and reduce the range of the solder resist ink layer; and through two roll coating processes, the thickness range of the overall solder resist ink layer can be reduced; at the same time, in the present application, the first solder resist ink layer is a conventional matte black ink or other conventionally used solder resist inks, and the second solder resist ink layer is a transparent material or a translucent material. The second solder resist ink layer covers the first solder resist ink layer. During the development process, the second solder resist ink layer exists as a protective layer on the surface of the first solder resist ink layer, which can prevent the first solder resist ink layer from being corroded by the developer, thereby improving the stability of the first solder resist ink layer, ensuring the stability of the welding position, and avoiding display screen distortion.

[0032] In this application, the first solder resist ink layer and the second solder resist ink layer are first coated globally, and then the first solder resist ink layer and the second solder resist ink layer are exposed and developed to expose the circuit pattern that needs to be welded or revealed. During the exposure and development process, the first solder resist ink layer and the second solder resist ink layer are exposed and developed together. In this application, the second solder resist ink layer is a transparent or translucent material, and the first solder resist ink layer is a conventional matte black ink or other conventionally used solder resist ink. The second solder resist ink layer does not affect the exposure and development effect of the first solder resist ink layer. In addition, in the PCB structure finally formed in this application, the first solder resist ink layer and the second solder resist ink layer cover the positions in the PCB board that do not require welding, which have a solder resist effect on subsequent processes.

[0033] Example 2

[0034] like Figure 1As shown, a display screen proposed in the present application includes a PCB board 11 and a light-emitting chip 21 welded on the PCB board 11, wherein the light-emitting chip 21 is distributed in a Bayer array, and the side of the light-emitting chip 21 that does not abut against the PCB board 11 is sealed by a sealing layer 25; the surface of the PCB board 11 close to the light-emitting chip 21 is sequentially covered with a first solder resist ink layer 13 and a second solder resist ink layer 14 by a roll coating process, wherein the first solder resist ink layer 13 and the second solder resist ink layer 14 cover positions in the PCB board 11 where no welding is required; the second solder resist ink layer 14 covers the surface of the first solder resist ink layer 13, and the second solder resist ink layer 14 is made of a transparent or translucent material. A circuit pattern 12 is pre-formed on the PCB board 11.

[0035] In the present application, the first solder resist ink layer uses matte black ink. Specifically, the matte black ink can be applied to the surface of the PCB board by a roll coating process to form a matte black bottom layer, and the thickness of the first solder resist ink layer is 10-40 μm. After the first solder resist ink layer is formed, the first pre-baking is performed to make the first solder resist ink layer initially solidified, and then the second solder resist ink layer is rolled.

[0036] The second solder resist ink layer is made of transparent or semi-transparent material. The thickness of the second solder resist ink layer is 5-40 μm. After the second solder resist ink layer is formed, it is pre-baked for the second time to make the second solder resist ink layer initially solidified, and then exposed and developed.

[0037] The first solder resist ink layer and the second solder resist ink layer are exposed and developed at the same time, so that the circuit pattern to be soldered is exposed. The exposure can be performed according to customer needs or subsequent needs. During the development, the circuit pattern to be soldered / exposed later is exposed; during the development process, the surface of the second solder resist ink layer is microscopically roughened.

[0038] By controlling the developing temperature, the transmission speed of the PCB board and the spraying pressure, the transparency of the surface of the second solder mask ink layer is maintained between 30% and 90%, where 100% transparency means completely transparent and 0% transparency means completely opaque. The transparency of the protective layer ink in this application is best between 30-90%; when the transparency is greater than 90%, the developer cannot bite the protective layer ink due to the reflection of the ink exposure light source and the smooth surface, which will cause the finished patch flux to be unable to diffuse and cause screen distortion. When the transparency is less than 30%, the ink surface is too dark, blocking the matte black color of the bottom layer, which is not conducive to the color consistency of the finished product.

[0039] Specifically, after development, the transparency of the surface of the second solder resist ink layer decreases as the development temperature increases, and the transparency of the surface of the second solder resist ink layer increases as the transmission speed of the PCB board increases; the transparency of the surface of the second solder resist ink layer decreases as the spray pressure increases.

[0040] By controlling the developing temperature, the transmission speed of the PCB board and the spraying pressure, the surface roughness of the second solder resist ink layer is made 0.1-12.5μm. When the surface roughness of the second solder resist ink layer is too large or too small, the subsequent solder flux of the patch cannot diffuse, which leads to the defect of screen flower.

[0041] After development, the roughness of the surface of the second solder resist ink layer increases with the increase of the development temperature, and the roughness of the surface of the second solder resist ink layer decreases with the increase of the transmission speed of the PCB board; the roughness of the surface of the second solder resist ink layer increases with the increase of the spray pressure.

[0042] Specifically, the relationship between surface roughness and other parameters in this application is: when the development temperature increases by 1 degree, or the speed decreases by 0.3-0.5m / min, or the spray pressure increases by 0.3-0.6KG, the surface roughness Ra will increase by 0.5-5μm and the transparency will decrease by 5-20% accordingly.

[0043] In the present application, the first solder resist ink layer and the second solder resist ink layer are covered on the circuit pattern and non-circuit pattern of the PCB board by rolling coating. The rolling coating method can ensure that the first solder resist ink layer and the second solder resist ink layer are formed in sequence. As shown in Table 1, the thickness of the first solder resist ink layer and the second solder resist ink layer at different positions when the rolling coating process of the present application forms the first solder resist ink layer and the second solder resist ink layer. The thickness of the solder resist ink layer coated on the line surface, the substrate and the large copper foil in the rolling coating process is different. By controlling the ink thickness in different areas, it is ensured that the surface range of the first solder resist ink layer and the second solder resist ink layer formed is small. For example, the thickness of the solder resist ink layer formed at the raised position on the PCB board is small, and the thickness of the solder resist ink layer formed at the relatively recessed position on the PCB board is large. The thickness of the first solder resist ink layer and the second solder resist ink layer can be accurately controlled by the rolling coating process to ensure that the surface thickness range of the first solder resist ink layer and the second solder resist ink layer is controlled within 5μm.

[0044] Table 1 Thickness of solder mask ink layer formed by roller coating process

[0045]

[0046] In Table 1, line surface refers to an area in the circuit pattern of the PCB board whose cross-sectional area is less than the first threshold, large copper skin refers to an area in the circuit pattern of the PCB board whose cross-sectional area is greater than or equal to the first threshold, and substrate refers to an area on the surface of the PCB board without a circuit pattern.

[0047] That is, the thickness of the first solder resist ink layer on the first circuit area is 5-15μm; the thickness of the first solder resist ink layer on the second circuit area is 5-20μm; the thickness of the first solder resist ink layer on the non-circuit area is 15-30μm. The thickness of the second solder resist ink layer on the first circuit area is 10-20 microns; the thickness of the second solder resist ink layer on the second circuit area is 10-20μm; the thickness of the second solder resist ink layer on the non-circuit area is 20-45μm.

[0048] The material of the second solder resist ink layer includes the following components in weight fractions: 16-20 parts of phenolic epoxy resin, 22-28 parts of o-cresol epoxy resin, 4-6 parts of acrylate, 27-33 parts of barium sulfate, 2-4 parts of photosensitizer, 1.8-2.2 parts of defoaming agent, 0.9-1.1 parts of silicon dioxide, 0.9-1.1 parts of melamine, and 13-17 parts of high boiling point aromatic hydrocarbon solvent.

[0049] The high boiling point aromatic solvent is prepared by mixing dimethyl glutarate, dimethyl adipate and dimethyl succinate in a certain proportion, specifically comprising: 25-60 parts of dimethyl glutarate, 20-50 parts of dimethyl adipate and 10-30 parts of dimethyl succinate.

[0050] In the present application, phenolic epoxy resin, o-cresol epoxy resin, barium sulfate and high-boiling point aromatic solvent are all transparent materials. Therefore, it can be ensured that the second solder resist ink layer is a transparent material, which does not change the color of the first solder resist ink layer and protects and shields the first solder resist ink layer, while also not affecting the normal exposure and development of the first solder resist ink layer. In addition, phenolic epoxy resin and o-cresol epoxy resin have the characteristic of being resistant to development. With specific development conditions, it is ensured that the surface roughness of the second solder resist ink layer after development is maintained within the range of 0.1-12.5μm, ensuring that the surface appearance of the final PCB board is consistent, and avoiding flower screen defects caused by large differences in the surface of the PCB board.

[0051] The components of the second solder resist ink layer in the present application ensure that it can be exposed and developed together with the first solder resist ink layer, so that the graphic area that needs to be soldered is exposed and the subsequent process can proceed normally.

[0052] like Figure 2-Figure 4As shown, the display screen includes a PCB board 11 and a light-emitting chip 21 soldered on the PCB board 11, the light-emitting chip 21 is distributed in a Bayer array, and the side of the light-emitting chip 21 that is not in contact with the PCB board 11 is sealed by a sealing layer 25. A first pad 22 is formed in the area on the surface of the PCB board 11 that is not coated with the first solder resist ink layer 13 and the second solder resist ink layer 14, and a second pad 23 is provided in the light-emitting chip 21, and the first pad 22 and the second pad 23 are connected. When the light-emitting chip 21 is installed upright in the PCB board 11, the first pad 22 and the second pad 23 are connected through a wire 24; when the light-emitting chip 21 is flipped in the PCB board 11, the first pad 22 and the second pad 23 are directly connected.

[0053] A front-mounted chip refers to connecting the second pad 23 of the light-emitting chip 21 to the first pad 22 on the PCB board 11 through a wire 24. This method requires soldering the wire 24 between the second pad 23 of the light-emitting chip 21 and the first pad 22 of the PCB board 11 to form an electrical connection. A flip-chip refers to directly flipping the light-emitting chip 21 on the PCB board 11, and connecting the second pad 23 of the light-emitting chip 21 to the first pad 22 on the PCB board 11 through a solder ball.

[0054] like Figure 2 As shown in the figure, it is a schematic diagram of the top mounting and the flip mounting when the light emitting chip 21 is packaged by the SMD process; a single light emitting chip 21 is packaged and then soldered on the PCB board 11, which is usually used for display modules with a pitch of more than P1.0. A driving IC 26 is also arranged on the side of the PCB board 11 away from the light emitting chip 21, which is used to control the operating state of the light emitting chip 21.

[0055] like Figure 3 As shown in the figure, it is a schematic diagram of the top-mounting and flip-mounting when the light-emitting chip 21 is packaged by the IMD process; the matrix integrated package (IMD) is to package two, four or more groups of light-emitting chips 21 in a small device unit. Typical IMD packages exist in the form of 2×2 or four-in-one. Four-in-one means that each IMD package includes 4 pixel groups, and each pixel group consists of RGB three-color light-emitting chips 21. IMD is usually used for display modules with a pitch of P0.9.

[0056] like Figure 4 As shown in the figure, it is a schematic diagram of the top-mounting and flip-mounting when the light-emitting chip 21 is packaged by the COB process; COB technology can interconnect multiple light-emitting chips 21 with the PCB board 11 and package them together. COB technology does not use a bracket, but directly solders the light-emitting chip 21 to the PCB board 11, reducing the number of solder joints, so the failure rate will be reduced. The technical route of COB is mainly based on products with pitches of P0.9 and P1.2.

[0057] It can be understood that the above embodiments only express the preferred implementation methods of the present application, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application; it should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, the above-mentioned technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present application; therefore, all equivalent changes and modifications made to the scope of the claims of the present application should belong to the scope covered by the claims of the present application.

Claims

1. A display screen, characterized in that: It comprises a PCB board and a light-emitting chip welded on the PCB board, wherein the light-emitting chips are distributed in a Bayer array, and the side of the light-emitting chip that is not in contact with the PCB board is sealed by a sealing layer; The surface of the PCB board close to the light-emitting chip is sequentially covered with a first solder resist ink layer and a second solder resist ink layer through a roll coating process, and the first solder resist ink layer and the second solder resist ink layer cover positions on the PCB board where no welding is required; the second solder resist ink layer covers the surface of the first solder resist ink layer, and the second solder resist ink layer is made of a transparent or translucent material.

2. A display screen according to claim 1, characterized in that: The surface roughness of the second solder resist ink layer after exposure and development is 0.1-12.5 μm.

3. A display screen according to claim 1, characterized in that: The transparency of the second solder resist ink layer after exposure and development is 30%-90%.

4. A display screen according to claim 1, characterized in that: The thickness of the first solder resist ink layer is 10-40 μm, and the thickness of the second solder resist ink layer is 5-40 μm.

5. A display screen according to claim 1, characterized in that: The surface of the PCB board is provided with a first circuit area, a second circuit area and a non-circuit area, and the thickness of the first solder resist ink layer in the first circuit area, the second circuit area and the non-circuit area is different; The first circuit region is a region in the circuit pattern whose cross-sectional area is smaller than a first threshold, and the second circuit region is a region in the circuit pattern whose cross-sectional area is greater than or equal to the first threshold.

6. A display screen according to claim 5, characterized in that: The thickness of the first solder resist ink layer on the first circuit area is 5-15 μm; the thickness of the first solder resist ink layer on the second circuit area is 5-20 μm; The thickness of the first solder resist ink layer on the non-circuit area is 15-30 μm.

7. A display screen according to claim 6, characterized in that: The thickness of the second solder resist ink layer on the first circuit area is 10-20 μm; the thickness of the second solder resist ink layer on the second circuit area is 10-20 μm; The thickness of the second solder resist ink layer on the non-circuit area is 20-45 μm.

8. The display screen according to claim 1, characterized in that: A first pad is formed on the surface of the PCB board in an area where the first solder resist ink layer and the second solder resist ink layer are not coated, a second pad is arranged in the light emitting chip, and the first pad and the second pad are connected.

9. A display screen according to claim 8, characterized in that: When the light emitting chip is mounted upright in the PCB board, the first pad and the second pad are connected via a wire; when the light emitting chip is flipped in the PCB board, the first pad and the second pad are directly connected.

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