Method for forming gap material bumps

Abstract

The method for forming the gap material bumps includes: providing a substrate, and the substrate has an alignment film thereon; placing a metal mold on the alignment film, and the metal mold has a plurality of through holes penetrating the metal mold; filling a light-cured material into the through holes of the metal mold, and pre-curing the light-cured material by ultraviolet rays; removing the metal mold; and after removing the metal mold, secondarily curing the light-cured material by ultraviolet rays to form a plurality of gap material bumps, wherein the alignment film and the material of the gap material bumps are different.

Description

Technical Field

[0001] This disclosure relates to a method for forming gap material bumps. Background Technology

[0002] As displays strive for higher resolution, the size of individual pixels continues to shrink. Traditional liquid crystal display panels, such as STN (Super-twisted Nematic) displays, have gradually been replaced by thin-film transistor liquid crystal displays (TFT-LCDs). The characteristics of traditional gap control materials no longer meet product requirements. Traditional gap control materials consist of micron-sized spherical particles, evenly sprinkled within the liquid crystal panel area, and then secured around the perimeter with encapsulating adhesives. However, the tendency of spherical particles to aggregate makes it difficult for traditional gap materials to distribute evenly, resulting in an inability to completely fix the gap between the two ITO glass panes of the display. Furthermore, due to the geometric characteristics of the spherical particles, they are prone to displacement, leading to light leakage and reducing display quality. Photocurable gap control materials, made from photosensitive polymers, can be exposed to specific areas to produce a cured adhesive, effectively maintaining the gap between the two ITO glass panes and preventing light leakage, significantly improving display performance.

[0003] Currently, most common photocurable gap control materials on the market are made by spin coating on a substrate and then exposure and development. Although they can produce highly stable finished products, the process is complicated, resulting in a relatively long manufacturing time. In addition, due to the characteristics of spin coating and development processes, a lot of waste adhesive is generated, which increases costs and carbon emissions.

[0004] In summary, new methods are urgently needed to form gap material bumps to overcome the above problems. Summary of the Invention

[0005] One embodiment of this disclosure provides a method for forming spacer bumps, comprising: providing a substrate having an alignment film on the substrate; placing a metal mold on the alignment film, the metal mold having a plurality of through holes penetrating the metal mold; filling the through holes of the metal mold with a photocurable material and pre-curing the photocurable material with ultraviolet light; removing the metal mold; and after removing the metal mold, second-curing the photocurable material with ultraviolet light to form a plurality of spacer bumps, wherein the alignment film and the spacer bumps are made of different materials.

[0006] In some embodiments, each through hole has an upper opening flush with the upper surface of the metal mold and a lower opening flush with the lower surface of the metal mold. The upper opening has a first size, the lower opening has a second size, and the ratio of the first size to the second size is 80:100 to 90:100.

[0007] In some embodiments, the substrate includes an array substrate, a color filter substrate, or a color filter on array (COA).

[0008] In some embodiments, the energy density ratio of the ultraviolet light of the pre-cured UV-curing material to that of the secondary-cured UV-curing material is 1:2 to 1:4.

[0009] In some embodiments, the energy density of the ultraviolet light in the pre-cured UV-curable material is 200 mJ / cm². 2 Up to 300mJ / cm 2 .

[0010] In some embodiments, the step of filling the through-holes of the metal mold with photocurable material is performed using inkjet printing.

[0011] In some embodiments, the photocurable material includes a photoinitiator and a monomer, and the weight ratio of the photoinitiator to the monomer is from 0.2:100 to 2:100.

[0012] In some embodiments, the photoinitiator includes a free radical photoinitiator, a cationic photoinitiator, or a combination thereof.

[0013] In some implementations, the height of the spacer bumps is 4 to 10 micrometers.

[0014] In some embodiments, the hardness of the spacer bumps is from 0.3 GPa to 0.55 GPa.

[0015] In some implementations, the step of filling the photocurable material is performed simultaneously with the step of pre-curing the photocurable material with ultraviolet light. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an alignment film on a substrate, representing one of the embodiments of this disclosure.

[0017] Figure 2 This is a top view of the metal mold.

[0018] Figure 3 This is a schematic diagram of a through hole in some embodiments of this disclosure.

[0019] Figure 4 This is a schematic diagram of some embodiments of the present disclosure, in which a photocurable material is filled into a through-hole and the photocurable material is pre-cured.

[0020] Figure 5This is a schematic diagram showing the metal mask after removal in some embodiments of this disclosure.

[0021] Figure 6 This is a schematic diagram of a secondary curing of a photocurable material to form spacer bumps, as described in some embodiments of this disclosure.

[0022] Symbol Explanation

[0023] D: Distance

[0024] H: Height

[0025] S1: First dimension

[0026] S2: Second size

[0027] 100: Metal mold

[0028] 101: Through hole

[0029] 101B: Lower side opening

[0030] 101U: Top opening

[0031] 115: Photocurable materials

[0032] 120: Inkjet unit

[0033] 130, 150: Ultraviolet light

[0034] 170: Gap Material Protrusion

[0035] 200:Substrate

[0036] 201:Alignment film Detailed Implementation

[0037] One embodiment of this disclosure provides a method for forming a spacer bump, including: as Figure 1 In some embodiments shown, a substrate 200 is provided, and an alignment film 201 is provided on the substrate 200. A metal mold 100 is placed on the alignment film 201, and the metal mold 100 has a plurality of through holes 101 penetrating the metal mold 100, such as... Figure 2 As shown. Figure 3 As shown, the through hole 101 is a cylinder that is narrower at the top and wider at the bottom. The upper opening 101U of the through hole 101 is flush with the upper surface of the metal mold 100. The lower opening 101B of the through hole 101 is flush with the lower surface of the metal mold 100. It can be understood that... Figure 2 and 3The number and shape of the through holes 101 are for illustrative purposes only and are not intended to limit the invention. For example, the number of through holes 101 may be greater than or less than six, depending on design requirements. Furthermore, the top view shape of the through holes 101 is not limited to a circle; it may also be a polygon (such as a triangle, square, rectangle, hexagon, or other polygon), an ellipse, or other suitable shape. Regardless of the top view shape, the upper opening 101U of the through hole 101 has a first dimension S1, and the lower opening 101B has a second dimension S2, with the ratio of the first dimension S1 to the second dimension S2 being 80:100 to 90:100. If the upper opening 101U is too large, it may be difficult to remove the metal mold 100 afterward. If the upper opening 101U is too small, it may be difficult to fill the through hole 101 with photocurable material, resulting in air bubbles remaining in the spacer bumps.

[0038] In some embodiments, substrate 200 includes an array substrate, a color filter substrate, or a color filter-on-array substrate. It is understood that the active units (such as transistors on the array substrate or color filter-on-array substrate) and / or passive units (such as color filters) of substrate 200 are sandwiched between the substrate material (not shown) and alignment film 201 of substrate 200. The substrate material may be glass, plastic, metal, semiconductor, or other suitable materials.

[0039] like Figure 4 As shown, photocurable material 115 is then filled into the through-hole 101 of the metal mold 100, and the photocurable material 115 is pre-cured with ultraviolet light 130. In some embodiments, the photocurable material 115 can be inkjet printed into the through-hole 101 using an inkjet printer 120. The advantage of this approach is that the photocurable material 115 only fills the through-hole 101 and does not form on the upper surface of the metal mold 100, thus reducing the amount of photocurable material 115 used and saving costs. Compared with photolithography to form spacer bumps, the cost of the metal mold 100 is lower than that of the photomask. Furthermore, in the photolithography process, other photocurable materials besides the spacer bumps are removed (developed) and are difficult to reuse. In other words, the method of forming spacer bumps with a metal mold can significantly reduce the amount of photocurable material used and lower costs.

[0040] In some embodiments, the photocurable material 115 comprises a photoinitiator and a monomer, with a weight ratio of photoinitiator to monomer of 0.2:100 to 2:100. If the amount of photoinitiator is too low, the pre-cured photocurable material 115 cannot be formed and will collapse after the metal mold 100 is removed. If the amount of photoinitiator is too high, the molecular chain segments are too short, resulting in a material that is too hard and brittle, lacking elastic recovery toughness. In some embodiments, the photoinitiator includes a free radical photoinitiator, a cationic photoinitiator, or a combination thereof. In some embodiments, the monomer may be a common acrylate monomer.

[0041] In some embodiments, the energy density of the ultraviolet light 130 of the pre-cured photocurable material 115 is 200 mJ / cm². 2 Up to 300mJ / cm 2 If the energy density of the ultraviolet light 130 is too low, the photocurable material 115 will not be able to form and will collapse after the metal mold 100 is removed. If the energy density of the ultraviolet light 130 is too high, the photocurable material 115 may completely cure and adhere to the metal mold 100. As a result, when the metal mold 100 is removed, some of the cured photocurable material may remain on the metal mold 100, causing damage to the final spacer bump. Furthermore, it should be understood that the step of filling the photocurable material 115 into the through-hole 101 and the step of pre-curing the photocurable material 115 may be performed simultaneously or not simultaneously. If they are performed simultaneously, the photocurable material 115 is not pre-cured after the photocurable material 115 has filled the through-hole 101, but rather pre-cured during the filling of the photocurable material 115 into the through-hole 101 (e.g., when the photocurable material 115 is dripped into the through-hole 101). This avoids the problem of different pre-curing degrees of the photocurable material 115 in different parts of the through-hole 101 (such as the bottom and top). On the other hand, the pre-curing time, which is the time it takes for the photocurable material 115 to fill the through-hole 101, can save process time.

[0042] Then as Figure 5 As shown, the metal mold 100 is removed, leaving the pre-cured photocurable material 115 on the alignment film 201. Since the photocurable material 115 is pre-cured, it will not collapse like a liquid. Furthermore, the pre-cured photocurable material 115 will not adhere to the surface of the metal mold 100, thus preventing damage to the spacer bumps. In some embodiments, the metal mold 100 is magnetic, allowing it to be removed magnetically. Because the pre-cured photocurable material 115 does not adhere to the surface of the metal mold 100, there is no need to form an additional release layer between the metal mold 100 and the photocurable material 115.

[0043] Then as Figure 6As shown, after removing the metal mold 100, the photocurable material 115 is cured a second time with ultraviolet light 150 to form multiple spacer bumps 170. It is understood that the material used for the alignment film 201 can be polyimide (PI), which differs from the material used for the spacer bumps 170 (such as the cured photocurable material). In this way, materials can be selected separately for the properties required for the alignment film 201 (Young's modulus greater than 3 GPa) and the properties required for the spacer bumps 170 (Young's modulus greater than 4.5 GPa), without compromising between them.

[0044] In some embodiments, the energy density ratio of the ultraviolet 130 of the pre-cured UV-curable material 115 to the ultraviolet 150 of the secondary-cured UV-curable material 115 is 1:2 to 1:4. If the energy density of the ultraviolet 150 is too low, the hardness of the spacer bump 170 will be too low, making it prone to deformation in subsequent applications and degrading the efficiency of the device. If the energy density of the ultraviolet 150 is too high, it will consume too much energy and cause the spacer bump 170 to become brittle.

[0045] In some embodiments, the height of the spacer bump 170 is 4 to 10 micrometers. In some embodiments, the hardness of the spacer bump is 0.3 GPa to 0.55 GPa. Generally, the height of spacer bumps formed by photolithography-cured materials is less than 4 micrometers, otherwise they are prone to collapse. The method described in this disclosure can form a spacer bump 170 with a relatively high height. Thus, the spacer bump 170 is formed on the substrate 200. In some embodiments, the substrate can then be combined with another substrate, and liquid crystal can be filled into the gap between the substrate and the other substrate. After encapsulation, a so-called liquid crystal display is completed.

[0046] In summary, the method provided in this disclosure can form a spacer bump 170, which can reduce costs by omitting the photomask and reducing the amount of photocurable material 115 used.

[0047] To make the foregoing contents and other objects, features and advantages of this disclosure more apparent and understandable, embodiments are described below in conjunction with the accompanying drawings for detailed explanation:

[0048] Example

[0049] In the following embodiments, the metal mold 100 used has six through holes 101 penetrating the metal mold 100, such as... Figure 2 As shown. The metal mold 100 is made of magnetic stainless steel or nickel alloy. The through hole 101 is a cylinder that is narrower at the top and wider at the bottom, as shown. Figure 3As shown. The upper opening 101U of the through hole 101 is flush with the upper surface of the metal mold 100, and its shape is circular, with a first dimension S1, such as a diameter of 20 micrometers. The lower opening 101B of the through hole 101 is flush with the lower surface of the metal mold 100, and its shape is circular, with a second dimension S2, such as a diameter of 24 micrometers. The height H of the through hole 101 (i.e., the thickness of the metal mold 100) is 5 micrometers. The distance D between two adjacent through holes 101 is 4 micrometers.

[0050] Example 1

[0051] 50 parts by weight of acrylate monomer TMPTA, 50 parts by weight of acrylate monomer PETA, 20 parts by weight of aliphatic polyurethane acrylate (DOUBLEMER 584 purchased from Double Bond Chemical Ind., Co., Ltd., dissolved in HDDA at a concentration of 12%), 0.8 parts by weight of free radical photoinitiator 184 (purchased from Mufeng Industrial Co., Ltd.), and 0.4 parts by weight of free radical photoinitiator 819 (purchased from Mufeng Industrial Co., Ltd.) were mixed to form the photocurable material UV-1. The chemical structure of TMPTA is as follows: The chemical structure of PETA is The chemical structure of HDDA is The chemical structure of free radical photoinitiator 184 is as follows: The chemical structure of free radical photoinitiator 819 is as follows:

[0052]

[0053] A metal mold was placed on a PI alignment film (100 micrometers thick, taken from the Institute of Materials and Chemistry, Industrial Technology Research Institute, Young's modulus 4.2 GPa) on a glass substrate, ensuring a tight seal. Six drops of UV-1 photocurable material were inkjet-printed into each through-hole of the metal mold to fill the holes, simultaneously using a low energy density (250 mJ / cm²). 2 The material is pre-cured with ultraviolet light to shape it. Then the metal mold is removed, and the curing process is performed with a high energy density (900 mJ / cm²). 2 The pre-cured photocurable material was irradiated with ultraviolet light for 2 seconds to completely cure it into spacer bumps. An MTS XPW Nanoindenter (purchased from KLA Instruments) was used. TM The hardness (0.53 GPa) and Young's modulus (7.1 GPa) of the spacer bump were tested. The shape of the spacer bump conforms to a through hole and is a cylinder that is narrower at the top and wider at the bottom. The upper side of the spacer bump is circular with a diameter of 20 micrometers. The lower side of the spacer bump is circular with a diameter of 22.5 micrometers. The height of the spacer bump is 4.75 micrometers.

[0054] Example 2

[0055] A metal mold was placed on a PI alignment film (100 micrometers thick, taken from the Institute of Materials and Chemistry, Industrial Technology Research Institute, Young's modulus 4.2 GPa) on a glass substrate, ensuring a tight seal. Six drops of UV-1 photocurable material were inkjet-printed into each through-hole of the metal mold to fill the holes, simultaneously using a low energy density (250 mJ / cm²). 2 The material is pre-cured with ultraviolet light to shape it. Then the metal mold is removed, and the material is cured with a high energy density (500 mJ / cm²). 2 The pre-cured UV-cured material was irradiated with ultraviolet light for 3 seconds to fully cure it into a spacer bump. The hardness (0.35 GPa) and Young's modulus (6.1 GPa) of the spacer bump were tested using a nano indenter. The shape of the spacer bump conforms to a through-hole and is also a cylinder that is narrower at the top and wider at the bottom. The upper side of the spacer bump is circular with a diameter of 20 micrometers. The lower side of the spacer bump is circular with a diameter of 22.5 micrometers. The height of the spacer bump is 4.71 micrometers.

[0056] Example 3

[0057] Take 50 parts by weight of acrylate monomer TMPTA, 50 parts by weight of acrylate monomer PETA, 20 parts by weight of aliphatic polyurethane acrylate DOUBLEMER 584, 0.4 parts by weight of free radical photoinitiator 184, and 0.2 parts by weight of free radical photoinitiator 819 and mix them to form UV-2 photocurable material.

[0058] A metal mold was placed on a PI alignment film (100 micrometers thick, taken from the Institute of Materials and Chemistry, Industrial Technology Research Institute, Young's modulus 4.2 GPa) on a glass substrate, ensuring a tight seal between the two. Six drops of UV-curable material (UV-2) were inkjet-printed onto each through-hole of the metal mold to fill the via, simultaneously using a low energy density (250 mJ / cm²). 2 The material is pre-cured with ultraviolet light to shape it. Then the metal mold is removed, and the curing process is performed with a high energy density (900 mJ / cm²). 2 The pre-cured UV-cured material was irradiated with ultraviolet light for 3 seconds to fully cure it into a spacer bump. The hardness (0.43 GPa) and Young's modulus (6.4 GPa) of the spacer bump were tested using a nano indenter. The shape of the spacer bump conforms to a through-hole and is also a cylinder that is narrower at the top and wider at the bottom. The upper side of the spacer bump is circular with a diameter of 20 micrometers. The lower side of the spacer bump is circular with a diameter of 22.5 micrometers. The height of the spacer bump is 4.77 micrometers.

[0059] Comparative Example 1

[0060] Six drops of UV-1 photocurable material were directly inkjet printed onto a PI alignment film, simultaneously using a low energy density (250 mJ / cm²). 2 The UV-cured material is then pre-cured using ultraviolet light. This is followed by high energy density (900 mJ / cm²). 2 The pre-cured UV-cured material is irradiated with ultraviolet light for 2 seconds to fully cure it. The cured UV-cured material is a flat circle with a height of 4 micrometers and a lateral dimension of 135 micrometers.

[0061] Comparative Example 2

[0062] A metal mold was placed on a PI alignment film (100 micrometers thick, taken from the Institute of Materials and Chemistry, Industrial Technology Research Institute, Young's modulus 4.2 GPa) on a glass substrate, ensuring a tight seal between the two. Six drops of UV-1 photocurable material were inkjet-printed into each through-hole of the metal mold to fill the via, simultaneously using a low energy density (250 mJ / cm²). 2 The material is pre-cured with ultraviolet light to shape it. Then the metal mold is removed, and the material is cured with a high energy density (350 mJ / cm²). 2 The pre-cured UV-cured material was irradiated with ultraviolet light for 4 seconds to fully cure it into a spacer bump. The hardness (0.21 GPa) and Young's modulus (5.0 GPa) of the spacer bump were tested using a nano indenter. The shape of the spacer bump conforms to a through-hole and is also a cylinder that is narrower at the top and wider at the bottom. The upper side of the spacer bump is circular with a diameter of 20.1 micrometers. The lower side of the spacer bump is circular with a diameter of 22.7 micrometers. The height of the spacer bump is 4.4 micrometers.

[0063] Comparative Example 3

[0064] Take 50 parts by weight of acrylate monomer TMPTA, 50 parts by weight of acrylate monomer PETA, 20 parts by weight of aliphatic polyurethane acrylate DOUBLEMER 584, 0.1 parts by weight of free radical photoinitiator 184, and 0.05 parts by weight of free radical photoinitiator 819 to form a photocurable material UV-3.

[0065] A metal mold was placed on a PI alignment film (100 micrometers thick, taken from the Institute of Materials and Chemistry, Industrial Technology Research Institute, Young's modulus 4.2 GPa) on a glass substrate, ensuring a tight seal between the two. Six drops of UV-3 photopolymer material were inkjet-printed into each through-hole of the metal mold to fill the via, simultaneously using a low energy density (250 mJ / cm²). 2 The UV-3 pre-cured photocurable material was used. However, the proportion of UV-3 photoinitiator was too low to allow the pre-cured photocurable material to take shape. After the metal mold was removed, it collapsed and could not be further cured into a spacer bump.

[0066] Although this disclosure has been presented above with several embodiments, it is not intended to limit the scope of this disclosure. Anyone skilled in the art can make any modifications and alterations without departing from the spirit and scope of this disclosure. Therefore, the scope of protection of this disclosure shall be determined by the appended claims.

Claims

1. A method for forming a gap material bump, comprising: A substrate is provided, and the substrate has an alignment film. A metal mold is placed on the alignment membrane, and the metal mold has a plurality of through holes penetrating the metal mold; The through-hole of the metal mold is filled with a photocurable material, and the photocurable material is pre-cured with ultraviolet light. Remove the metal mold; as well as After removing the metal mold, the photocurable material is cured a second time with ultraviolet light to form multiple spacer bumps. The alignment membrane is made of a different material than the spacer bump.

2. The method for forming a gap material protrusion as claimed in claim 1, wherein each of the through holes has an upper opening flush with the upper surface of the metal mold and a lower opening flush with the lower surface of the metal mold, the upper opening having a first size, the lower opening having a second size, and the ratio of the first size to the second size being 80:100 to 90:

100.

3. The method for forming the gap material bump as described in claim 1, wherein the substrate includes an array substrate, a color filter substrate, or an array substrate on a color filter.

4. The method for forming a gap material bump as described in claim 1, wherein the energy density ratio of the ultraviolet light used in the pre-curing of the photocurable material to the ultraviolet light used in the secondary curing of the photocurable material is 1:2 to 1:

4.

5. The method for forming the gap material bump as described in claim 1, wherein the energy density of the ultraviolet light used to pre-cur the photocurable material is 200 mJ / cm². 2 Up to 300mJ / cm 2 .

6. The method for forming a gap material bump as claimed in claim 1, wherein the step of filling the photocurable material into the through hole of the metal mold is performed by inkjet printing.

7. The method for forming a gap material bump as described in claim 1, wherein the photocurable material comprises a photoinitiator and a monomer, and the weight ratio of the photoinitiator to the monomer is 0.2:100 to 2:

100.

8. The method for forming a gap material bump as claimed in claim 1, wherein the photoinitiator comprises a free radical photoinitiator, a cationic photoinitiator, or a combination thereof.

9. The method for forming a spacer bump as claimed in claim 1, wherein the height of the spacer bump is 4 micrometers to 10 micrometers.

10. The method for forming a spacer bump as claimed in claim 1, wherein the hardness of the spacer bump is from 0.3 GPa to 0.55 GPa.

11. The method for forming a gap material bump as claimed in claim 1, wherein the step of filling with photocurable material and the step of pre-curing the photocurable material with ultraviolet light are performed simultaneously.

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