CN113682064A

CN113682064A - Display device packaging method

Info

Publication number: CN113682064A
Application number: CN202110894576.7A
Authority: CN
Inventors: 倪奎
Original assignee: Wuhan China Star Optoelectronics Semiconductor Display Technology Co Ltd
Current assignee: Wuhan China Star Optoelectronics Semiconductor Display Technology Co Ltd
Priority date: 2021-08-05
Filing date: 2021-08-05
Publication date: 2021-11-23

Abstract

The invention provides a display device packaging method, which comprises the following steps: providing a display device, wherein a first inorganic layer covering the display device is formed on the display device; printing ink on the first inorganic layer by inkjet printing; heating the ink; the ink is subjected to ultraviolet irradiation so as to be cured, the organic layer is formed on the first inorganic layer, and the ink is heated before being cured so as to be quickly leveled, so that the problem that the thickness of the organic layer formed by the ink is uneven is solved, and the mura defect is improved.

Description

Display device packaging method

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of display, in particular to a display device packaging method.

[ background of the invention ]

Organic Light Emitting diodes (OLE D) have been actively developed because of their advantages of simple structure, self-luminescence, fast response speed, ultra-Light and thin profile, and low power consumption. The Cathode (Cathode) and the light emitting layer (EML) of the OLED device are easy to be permeated by water (H)₂O) oxygen (O)₂) The reaction occurs, the service life and the display effect of the OLED device are greatly influenced, and the OLED device needs to be packaged to isolate water and oxygen. At present, the mainstream packaging methods include film packaging (TFE), glass powder packaging, retaining wall packaging and surface glue packaging. Since the thin film package can be applied to the wraparound display technology (i.e., flexible display technology), the thin film package is widely applied to the package of the OLED device. A common thin film packaging structure is in OLA first inorganic layer, an organic layer, and a second inorganic layer are sequentially formed on the ED device.

The organic layer is made by printing ink (ink) on the first inorganic layer, and curing the ink by Ultraviolet (UV) irradiation after natural leveling. However, on the one hand, gas (outgas) in the ink easily enters the OL ED device through a crack (pinhole) of the first inorganic layer, resulting in a small black spot on the display screen when the OLED device displays, and on the other hand, leveling abnormality easily occurs in the ink, resulting in uneven thickness of the formed organic layer film, thereby forming a display unevenness (mura) defect.

Therefore, the prior art has defects and needs to be improved and developed.

[ summary of the invention ]

The invention provides a display device packaging method which can effectively improve mura defects caused in the manufacturing process of an organic layer.

In order to solve the above problems, the present invention provides a display device packaging method, including: providing a display device, wherein a first inorganic layer covering the display device is formed on the display device; printing ink on the first inorganic layer by inkjet printing; heating the ink; ultraviolet light is irradiated to the ink to cure the ink, and an organic layer is formed on the first inorganic layer.

Wherein, after ultraviolet irradiation is carried out on the ink, the method further comprises the following steps:

a second inorganic layer is formed on the organic layer.

Wherein, heating the ink specifically includes:

the display device is placed on the carrier, and the carrier is heated by the heat source.

Wherein, the surface roughness of the side of the carrying platform contacted with the display device is not more than 40 um.

Wherein the heating temperature for heating the platform deck by the heat source is not more than 100 ℃.

Wherein the wavelength range of the ultraviolet light comprises 200-400 nm.

The lamp source of ultraviolet light includes, among others, a mercury lamp or an LED.

Wherein the time range for heating the ink comprises 10-60 minutes.

Wherein the ink is heated to cause gases to escape from the ink, the gases including water vapor and oxygen.

Wherein the display device comprises an organic electroluminescent display or a quantum dot light emitting diode.

The invention has the beneficial effects that: different from the prior art, the invention provides a display device packaging method, which comprises the following steps: providing a display device, wherein a first inorganic layer covering the display device is formed on the display device; printing ink on the first inorganic layer by inkjet printing; heating the ink; the ink is subjected to ultraviolet irradiation so as to be cured, the organic layer is formed on the first inorganic layer, and the ink is heated before being cured so as to be quickly leveled, so that the problem that the thickness of the organic layer formed by the ink is uneven is solved, and the mura defect is improved.

[ description of the drawings ]

Fig. 1 is a schematic flow chart of a display device packaging method according to an embodiment of the present invention;

fig. 2 is a schematic structural view of a display device provided in an embodiment of the present invention;

FIG. 3 is a schematic diagram of a structure formed by ink-jet printing according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an embodiment of the present invention formed by curing ink;

fig. 5 is a schematic structural diagram formed by the display device packaging method in the embodiment of the invention.

[ detailed description ] embodiments

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be noted that the following examples are only illustrative of the present invention, and do not limit the scope of the present invention. Likewise, the following examples are only some but not all examples of the present invention, and all other examples obtained by those skilled in the art without any inventive step are within the scope of the present invention.

In addition, directional terms mentioned in the present invention, such as [ upper ], [ lower ], [ front ], [ rear ], [ left ], [ right ], [ inner ], [ outer ], [ side ], and the like, refer to directions of the attached drawings only. Accordingly, the directional terms used are used for explanation and understanding of the present invention, and are not used for limiting the present invention. In the various figures, elements of similar structure are identified by the same reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. Moreover, some well-known elements may not be shown in the figures.

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

As shown in fig. 1, an embodiment of the present application provides a method for packaging a display device 110, which is applied in the field of display technology, and the specific flow is compared with the structure diagrams of fig. 2 to fig. 5, and may include the following steps:

s101, a step: a display device 110 is provided, wherein a first inorganic layer 120 is formed on the display device 110 to cover the display device.

Specifically, the method for packaging the display device 110 according to the embodiment of the present application is described in detail with reference to fig. 2 to 5. It should be understood that the relative arrangement of parts and steps, numerical expressions, and numerical values set forth in these embodiments should not be construed as limiting the scope of the present invention unless it is specifically stated otherwise. Further, the dimensions of the various elements shown in the figures are not necessarily drawn to scale relative to actual dimensions for ease of illustration, e.g., the thickness or width of some layers may be exaggerated relative to other layers. The following description of the exemplary embodiment(s) is merely illustrative and is not intended to limit the invention, its application, or uses in any way. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification as applicable. It should be noted that like reference numerals and letters refer to like items in the following figures, and thus, once an item is defined or illustrated in one figure, further discussion thereof will not be required in the subsequent description of the figures.

The display device 110 includes an organic electroluminescent display or a quantum dot light emitting diode, among others.

Specifically, when the display device 110 is an Organic Light-Emitting Diode (OLED), the structure of the conventional OLED device generally includes, from bottom to top, an Anode (Anode), a Hole Transfer Layer (HTL), an Emitting Layer (EML), an Electron Transfer Layer (ETL), a Cathode (Cathode), and a Capping Layer (CPL) that are sequentially stacked. At least one of the anode or the cathode needs to be transparent in order to transmit light emitted from the light emitting layer. Generally, the anode is selected as a transparent electrode, for example, the material of the anode is Indium Tin Oxide (ITO), and of course, the cathode may also be selected as a transparent electrode, which is not limited specifically. However, since the organic materials in the cathode and light emitting layers of an OLED device are water (H)₂O) and oxygen (O)₂) The OLED device is sensitive and easy to react with permeated water and oxygen, and the service life and the luminous efficiency of the OLED device are greatly influenced. Accordingly, the first inorganic layer 120 may be formed on the OLED device, and the first inorganic layer 120 covers the display device 110, i.e., the first inorganic layer entirely covers the display device 110.

Specifically, when a Quantum Dot Light Emitting diode (QLED) is used, the structure of the QLED device is very similar to that of an OLED device, and the main difference is that the Light Emitting layer of the QLED is made of Quantum Dot (Quantum dots) material, electrons (electrons) and holes (holes) on two sides of the Light Emitting layer converge in the Quantum Dot layer to form photons (exiton), and the photons recombine to emit Light. Based on the disadvantage that the quantum dots of the QLED device are easily affected by heat and moisture, the first inorganic layer 120 may be formed on the QLED device, and the display device 110 is covered by the first inorganic layer 120, that is, the entire surface of the first inorganic layer covers the display device 110, and the first inorganic layer 120 is used to isolate water and oxygen to protect the QLED device.

Fig. 2 shows the structure formed in step S101, which includes: a display device 110, and a first inorganic layer 120 covering the display device 110. In addition, a substrate (not numbered in the drawing) may be further formed below the display device 110, the display device 110 is completely isolated from water and oxygen by the substrate and the first inorganic layer 120 coated on the display device 110, generally, a film layer of the display device 110 needs to be fabricated on the substrate, the substrate is generally a rigid substrate, and when the display device 110 is a flexible device, the substrate is a flexible substrate.

Specifically, Plasma Enhanced Chemical Vapor Deposition (PECVD) is a technique for generating a solid film by activating a reaction gas with Plasma to promote a Chemical reaction on a substrate surface or in a near-surface space. The basic principle of the plasma chemical vapor deposition technology is that under the action of a high-frequency or direct-current electric field, source gas is ionized to form plasma, low-temperature plasma is used as an energy source, a proper amount of reaction gas is introduced, and the reaction gas is activated by plasma discharge to realize the chemical vapor deposition technology. Compared with conventional Chemical Vapor Deposition (CVD), PECVD plasma contains a large number of high-energy electrons that can provide the activation energy required in the CVD process, thereby changing the energy supply manner of the reaction system. Because the electron temperature in the plasma is as high as 10000K, the collision of electrons and gas phase molecules can promote the breaking and recombination of chemical bonds of reaction gas molecules to generate chemical groups with higher activity, and meanwhile, the whole reaction system keeps lower temperature. This feature allows CVD processes that originally required high temperatures to be carried out at low temperatures. The first inorganic layer 120 may be formed on the display device 110 by plasma chemical vapor deposition. In general, the material of the first inorganic layer 120 may be silicon oxide (SiO2), silicon nitride (SiN), silicon oxynitride (SiON), or the like.

S102, a step: the ink 130 is printed on the first inorganic layer 120 by inkjet printing.

Fig. 3 shows the structure formed in step S102, which includes: a display device 110, a first inorganic layer 120 covering the display device 110, and an ink 130 on the first inorganic layer 120. The ink 130 may be printed on the first inorganic layer 120 by means of inkjet printing.

Specifically, the ink 130 is printed on the first inorganic layer 120 by inkjet printing, many small particles of the ink 130 are formed on the first inorganic layer 120, and then the small particles of the ink 130 are naturally leveled to form a uniform ink layer. However, the area where the ink-jet printing is performed first may achieve the ink leveling faster than the area where the ink-jet printing is performed later, and when the next process step is performed after the ink-jet printing of the whole area is completed, the leveling states of the inks 130 in different areas are different, which may cause the difference in the film-forming uniformity of the ink-jet printing.

S103, a step: the ink 130 is heated.

Wherein the ink 130 is heated to cause gases, including water vapor and oxygen, to escape from the ink 130.

Specifically, the existing thin film encapsulation structure on the OLED device includes: the first inorganic layer 120, the organic layer 140, and the second inorganic layer 150 are sequentially stacked on the OLED device. The existing packaging method of the OLED device comprises the following steps: first, a first inorganic layer 120 is formed on the OLED device, then, the first inorganic layer 120 is printed by inkjet, and after it is naturally leveled, Ultraviolet (UV) light is applied to cure the ink 130 to form an organic layer 140, and finally, a second inorganic layer 150 is formed on the inorganic layer. However, the existing method for forming a thin film package has certain defects, for example, on one hand, due to equipment or process reasons, the abnormal flow of the ink 130 is easy to occur, resulting in uneven film thickness of the formed organic layer 140, thereby forming pin mura (display unevenness of a circular pattern) defect, stage mura (display unevenness of a stripe pattern) defect, and the like, and on the other hand, after a period of time elapses, the organic layer 140 formed by curing the ink 130 is easy to generate some gases (outsgas), such as water vapor and oxygen, and the generated water vapor and oxygen enter the OLED device through the crack (pinhole) in the first inorganic layer 120, resulting in small black spots on the display screen of the OLED device, thereby forming mura (display unevenness) defect.

Specifically, mura defects are phenomena that the pixel characteristics are changed due to pressure, scratch, offset, vibration, and pollution caused by equipment in a process, or due to the influence of environmental temperature and driving conditions, and finally corresponding display unevenness may be seen in display inspection. Various traces due to uneven brightness appear on the display screen, which are collectively called uneven display, and come from japanese "mottled" sounds. The manifestations are mainly 3 types: first, a little dark display portion is visible in a white picture; secondly, a little white display part can be seen in a dark picture; thirdly, the intermediate gray scale picture is visible. mura defects are roughly classified into abnormal mura-like alignment, uneven film thickness, substrate-like mura, abnormal TFT characteristics, and the like. mura defects have the following characteristics: without a clear definition, classification and degree determination is very difficult and no unified standard can be established at present.

In view of this, by executing step S103: as can be seen from the above, after a period of time elapses, the organic layer 140 formed by curing the ink 130 is prone to generate some gases, such as water vapor and oxygen, and by heating the ink 130, on one hand, the water vapor and oxygen which are prone to be generated in the ink 130 are allowed to escape from the ink 130 in advance, so that the problem that the gases generated in the ink 130 enter the OLED device through pinhole in the first inorganic layer 120, and a small black spot occurs on the display screen of the OLED device, thereby forming a mura defect can be effectively improved. On the other hand, by heating the ink 130, the ink 130 can be rapidly leveled, which is beneficial to forming a uniform organic layer 140, and the problem that the leveling abnormality of the ink 130 can be effectively improved, which causes uneven film thickness of the formed organic layer 140, thereby forming mura defects can be effectively solved.

Wherein, the step S103 specifically includes:

the display device 110 is placed on a stage, which is heated by a heat source.

Specifically, the heating of the ink 130 may be realized by placing the display device 110 on a stage (not shown in the drawings) and heating the stage by a heat source. The heat source is not particularly limited as long as the stage can be heated by the heat source to heat the ink 130, and for example, the heat source may be a heat exchanger connected to the stage, and the stage is heated by controlling the on-state of the heat source, and accordingly, the ink 130 is heated to allow the gas in the ink 130 to escape and the ink 130 to be rapidly leveled.

In addition, the heating temperature of the ink 130 can be controlled by controlling the heating temperature of the heat source, and the suitable heating temperature is selected according to different material characteristics of the ink 130, so that the escape of water vapor and oxygen in the ink 130 and the rapid leveling of the ink 130 are realized. Based on the material characteristics of the ink 130, for example, the ink 130 is formed by melting an organic material in a solvent, when the heating temperature of the ink 130 is too high, the ink 130 is easily vaporized and volatilized, so that the organic layer 140 cannot be formed subsequently, therefore, the heating temperature of the ink 130 cannot be too high, and the heating temperature for heating the stage by controlling the heat source is not more than 100 ℃, so as to ensure the stability of the performance of the ink 130. Meanwhile, in order to ensure the stability of the display device 110, the heating temperature for heating the stage by the heat source is not preferably 100 ℃.

Wherein, the surface roughness of the side of the carrier contacting the display device 110 is not more than 40 um.

As can be seen from the above, the mura defect is caused by the poor uniformity of the film thickness of the organic layer 140, since the organic layer 140 formed on the display device 110 is sensitive to the uniformity of the film thickness, when the step S103 is performed: the display device 110 is placed on the carrier, and when the carrier is heated by the heat source, the surface roughness of one side of the carrier, which is in contact with the display device 110, is not more than 40um, so that the uniformity of the thickness of the finally formed inorganic layer film is ensured. The surface roughness (surface roughness) is also called flatness, and refers to the roughness of small pitch and minute peak and valley of the machined surface. The distance between two wave crests or two wave troughs (wave distance) is very small (below 1 mm), and the micro geometrical shape error belongs to. The smaller the surface roughness, the smoother the surface. When the surface roughness of the side of the stage in contact with the display device 110 is not greater than 40um, the organic layer 140 with good film thickness uniformity formed on the display device 110 is facilitated, so that mura defects caused by uneven film thickness of the organic layer 140 are improved.

Wherein the time range for heating the ink 130 includes 10-60 minutes.

Specifically, in general, since water vapor and oxygen are easily generated in the ink 130, when the ink 130 is heated for 1 to 60 minutes, it is possible to realize escape of water vapor and oxygen easily generated in the ink 130 by heating. When the time for heating the ink 130 is 1 to 10 minutes, the ink 130 can be leveled by heating, and the longest time for heating in the gas escape and rapid leveling in step S103 is selected as the process time, so as to ensure that not only the water and oxygen in the ink 130 can escape by heating, but also the ink 130 can be leveled by heating, and therefore, preferably, the time range for heating the ink 130 is 10 to 60 minutes.

Note that the time for heating the ink 130 is not particularly limited as long as water and oxygen in the ink 130 can be released by heating and the ink 130 can be quickly leveled by heating, and the time for heating the ink 130 may vary depending on the material characteristics of the ink 130.

And S104: the ink 130 is irradiated with ultraviolet light to cure the ink 130, and an organic layer 140 is formed on the first inorganic layer 120.

Fig. 4 shows the structure formed in step S104, which includes: the display device 110, the first inorganic layer 120 covering the display device 110, and the organic layer 140 on the first inorganic layer 120.

Specifically, the UV coating is irradiated by ultraviolet light, then the photoinitiator is initiated to generate free radicals or ions, the free radicals or ions and double bonds in the prepolymer or unsaturated monomer perform a crosslinking reaction to form monomer genes, so that polymerization, crosslinking and grafting reactions are initiated, and the resin (the UV coating, the ink, the adhesive and the like) is converted from a liquid state to a solid state within seconds, wherein the change process is called UV curing. By executing step S103: after the ink 130 is heated to allow the gas in the ink 130 to escape and the ink 130 to rapidly level, the step S104 is executed: the ink 130 is irradiated with ultraviolet light to cure the ink 130, and an organic layer 140 is formed on the first inorganic layer 120. In this case, the uniformity of the formed organic layer 140 is good, and the mura defect is improved by effectively improving the problem of the uneven film thickness of the organic layer 140 formed by the ink 130.

Wherein the wavelength range of the ultraviolet light comprises 200-400 nm.

In particular, ultraviolet light (Ultra-Violet) has a wavelength in the range of 10-400nm in the electromagnetic spectrum, is a segment of electromagnetic radiation other than visible Violet light, and is invisible light. Generally, the method is subdivided into the following sections according to different properties: vacuum Ultraviolet (VUV) light with wavelength of 10-200 nm; short-wave Ultraviolet (UVC) with the wavelength of 200-280nm can be used for sterilization and disinfection; medium-wave Ultraviolet (UVB) with the wavelength of 290-320 nm; long-wave Ultraviolet (UVA) with the wavelength of 320-400nm can be used for photocuring printing plates. According to the material characteristics of the ink 130, different ultraviolet light is selected for the different inks 130 for irradiation, and preferably, when the wavelength range of the ultraviolet light is 200-400nm, the curing efficiency of the ink 130 is the highest, so when the ink is cured by the ultraviolet light, the wavelength range of the ultraviolet light is 200-400 nm.

It should be noted that the wavelength of the ultraviolet light is not particularly limited, but only the ink 130 can be cured under the irradiation of the ultraviolet light to form the organic layer 140, the wavelength of the ultraviolet light for curing the ink is different according to the material of the ink 130, and the wavelength of the ultraviolet light may be out of the range of 200-400nm depending on the material of the ink 130.

Specifically, the conventional ultraviolet light source mainly uses a mercury arc lamp (also called as an ultraviolet lamp or a mercury lamp), the mercury arc lamp is a transparent quartz tube which is packaged with mercury and has electrodes at two ends, when the filament is heated by electrifying, mercury vapor in the tube is excited to transition to an excited state, and when the filament returns to a ground state from the excited state, the mercury arc lamp emits ultraviolet light. Depending on the mercury vapor pressure in the tube, the emitted ultraviolet light also has a different spectrum, and can be classified into a low-pressure mercury lamp, a medium-pressure mercury lamp, and a high-pressure mercury lamp. The mercury vapor pressure of the low-pressure mercury lamp is 10-100kPa, the emitted ultraviolet light is linear discrete spectrum, the main emission wavelength is 254nm and 185nm, the low-pressure mercury lamp is low in power and generally only dozens of watts, meanwhile, the emission wavelength is extremely short, ozone is easily generated, air pollution is caused, and the low-pressure mercury lamp is rarely used in photocuring.

In particular, LEDs may also be used as a light source for uv light, such as uv LEDs. The ultraviolet LED is an LED having an emission center wavelength of 400nm or less, but an LED having an emission wavelength of more than 380nm may be called a near ultraviolet LED, and an LED having an emission wavelength of less than 300nm may be called a deep ultraviolet LED.

Further, it should be noted that the light source of the ultraviolet light is not particularly limited as long as the ultraviolet light required for curing the ink 130 can be generated, and for example, the ultraviolet light generated by the mercury lamp or the LED irradiates the ink 130 with the ultraviolet light to cure the ink 130, so that the organic layer 140 is formed on the first inorganic layer 120.

After the step S104, the method further includes:

and S105: a second inorganic layer 150 is formed on the organic layer 140.

Fig. 5 shows the structure formed in step S105, which includes: the display device 110, a first inorganic layer 120 encapsulating the display device 110, an organic layer 140 on the first inorganic layer 120, and a second inorganic layer 150 on the organic layer 140. The second inorganic layer 150 may be formed on the organic layer 140 by plasma chemical vapor deposition. In general, the material of the second inorganic layer 150 may be silicon oxide, silicon nitride, silicon oxynitride, or the like.

As can be seen from the above, the present invention provides a display device packaging method, including: providing a display device, wherein a first inorganic layer covering the display device is formed on the display device; printing ink on the first inorganic layer by inkjet printing; heating the ink; the ink is subjected to ultraviolet irradiation so as to be cured, the organic layer is formed on the first inorganic layer, and the ink is heated before being cured so as to be quickly leveled, so that the problem that the thickness of the organic layer formed by the ink is uneven is solved, and the mura defect is improved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A display device packaging method, comprising:

providing a display device, wherein a first inorganic layer covering the display device is formed on the display device;

printing ink on the first inorganic layer by inkjet printing;

heating the ink;

and irradiating ultraviolet light to the ink to cure the ink, so that an organic layer is formed on the first inorganic layer.

2. The display device packaging method of claim 1, further comprising, after the ultraviolet light irradiation of the ink:

a second inorganic layer is formed on the organic layer.

3. The method for encapsulating a display device according to claim 1, wherein the heating the ink specifically includes:

and placing the display device on a carrier, and heating the carrier through a heat source.

4. The method for packaging a display device according to claim 3, wherein a surface roughness of a side of the carrier contacting the display device is not more than 40 um.

5. The display device packaging method according to claim 3, wherein a heating temperature at which the stage is heated by the heat source is not more than 100 ℃.

6. The method for encapsulating a display device as claimed in claim 1, wherein the wavelength range of the ultraviolet light comprises 200-400 nm.

7. The display device packaging method of claim 1, wherein the lamp source of ultraviolet light comprises a mercury lamp or an LED.

8. The display device packaging method of claim 1, wherein the time period for heating the ink comprises 10-60 minutes.

9. The display device encapsulation method of claim 1, wherein heating the ink causes gases to escape from the ink, the gases including water vapor and oxygen.

10. The display device encapsulation method of claim 1, wherein the display device comprises an organic electroluminescent display or a quantum dot light emitting diode.