Cover plate packaging structure of silicon-based OLED

Abstract

The invention relates to the technical field of silicon-based OLEDs, and discloses a cover plate packaging structure of a silicon-based OLED, which comprises a silicon substrate, cover plate glass, cofferdam glue and surface glue, and is characterized in that the silicon substrate is provided with a display area and an isolation structure for isolating the cofferdam glue from the surface glue; the isolation structure comprises a first enclosing wall and a second enclosing wall which are arranged on the silicon substrate. The first enclosing wall and the second enclosing wall are arranged to form the buffer interlayer, and the overflow assembly is arranged, so that cofferdam glue and surface glue can be effectively isolated, and mutual dissolution of the cofferdam glue and the surface glue before curing is avoided; the second enclosing wall formed by the photoetching process provides a stable coating boundary for the surface glue, so that the dependence on the coating precision of the cofferdam glue is reduced, and the coating requirement of the surface glue is fixed; the overflow assembly provides a controlled discharge channel for redundant surface glue in the laminating process, so that the redundant surface glue can flow into the buffer interlayer, internal pressure generated by coating fluctuation or laminating extrusion of the surface glue can be relieved, the uniformity of the thickness of a packaging layer is promoted, and the packaging reliability is improved.

Description

Technical Field

[0001] This invention relates to the field of silicon-based OLED technology, and more particularly to a cover plate encapsulation structure for silicon-based OLEDs. Background Technology

[0002] As a core technology in the field of microdisplays, silicon-based OLEDs rely heavily on the barrier properties of the encapsulation structure against water vapor and oxygen for their lifespan and reliability. Since organic light-emitting materials and metal electrodes are extremely sensitive to water and oxygen, the sealing effect of the cover plate encapsulation structure directly determines the lifespan and display stability of the device.

[0003] Currently, the mainstream silicon-based OLED cover plate encapsulation method in the industry is a "cofferdam adhesive + surface adhesive + glass cover plate" structure. This structure involves coating a ring-shaped cofferdam adhesive around the display area of ​​the silicon substrate, coating the display area with surface adhesive, and finally covering it with a glass cover plate and curing it. Among them, the cofferdam adhesive is mainly used to support the cover plate, bond the substrate and the cover plate, and prevent water and oxygen intrusion from the sides. The surface adhesive is used to bond the display area and the cover plate and acts as a light path buffer layer to reduce reflection. However, before the adhesive cures, the inside of the panel lacks reliable support and relies solely on the surface tension of the adhesive to maintain the position of the cover plate, which can easily lead to bonding deviations or uneven gaps. The coating accuracy of the cofferdam adhesive is usually only ±15%, and its enclosure area fluctuates greatly. The surface adhesive coating is mostly done by inkjet printing, with an accuracy of about ±0.5%, which is still insufficient for high-precision applications. At the same time, before curing, the cofferdam adhesive and the surface adhesive are prone to mutual solubility after contact, affecting their respective functions and interface morphology, and reducing the reliability of the encapsulation.

[0004] To address these issues, the industry has attempted to introduce isolation structures, such as a partition wall between the cofferdam adhesive and the display area. This partition wall prevents direct contact between the cofferdam adhesive and the topcoat, thereby reducing mutual solubility. While these improvements enhance the controllability of the encapsulation process to some extent, they do not fundamentally solve the problem of inconsistent topcoat coating amounts caused by fluctuations in the cofferdam adhesive coating area. Furthermore, they do not provide a mechanism to accommodate and guide excessive flow of the topcoat during bonding. The precision requirements for topcoat coating remain high, and the process window is still relatively narrow. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a cover plate encapsulation structure for silicon-based OLEDs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A cover plate encapsulation structure for a silicon-based OLED includes a silicon substrate, a cover glass, a damming adhesive, and a surface adhesive. The silicon substrate has a display area and an isolation structure for isolating the damming adhesive and the surface adhesive.

[0008] The isolation structure includes a first enclosure and a second enclosure disposed on a silicon substrate. The first enclosure is located outside the second enclosure, and a buffer interlayer is formed between the two. The second enclosure is disposed around the display area. A dike adhesive is applied to the outside of the first enclosure. A surface adhesive is applied to the display area and contacts the inner wall of the second enclosure. An overflow component is disposed on the second enclosure.

[0009] Among them, the overflow component allows excess adhesive in the display area to pass through and flow into the buffer interlayer during the cover glass pressing process.

[0010] As a further embodiment of the present invention, the overflow assembly includes a plurality of overflow channels formed on the second wall, the overflow channels being used to connect the display area and the buffer interlayer.

[0011] As a further embodiment of the present invention, the overflow trough is composed of a flow guiding section and a flow diversion section.

[0012] As a further embodiment of the present invention, the flow guide is an inclined surface that slopes from the middle of the overflow channel toward the display area, and the flow diversion part is a straight channel connecting the highest point of the flow guide with the buffer interlayer.

[0013] As a further embodiment of the present invention, a ramp is provided in the buffer interlayer, the ramp having an inclined slope toward the root of the first wall.

[0014] As a further embodiment of the present invention, both the first and second walls are made of elastic plastic material. The second wall deforms when the cover glass is pressed together and closes the flow channel after the excess adhesive passes through the overflow groove.

[0015] As a further aspect of the present invention, the height of the first wall is greater than the height of the second wall.

[0016] As a further aspect of the present invention, the cofferdam adhesive contains a septum material, the initial height of which matches the initial height of the first wall.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This silicon-based OLED cover plate encapsulation structure, by setting a first and second perimeter wall to form a buffer interlayer and configuring an overflow component, can effectively isolate the cofferdam adhesive and the topcoat adhesive, thereby preventing them from dissolving each other before curing. The second perimeter wall, formed by photolithography, provides a stable coating boundary for the topcoat adhesive, reducing the dependence on the coating precision of the cofferdam adhesive, making the coating requirements of the topcoat adhesive more consistent and the process easier to achieve. The overflow component provides a controlled discharge channel for excess topcoat adhesive during the bonding process, allowing it to flow into the buffer interlayer. This helps to alleviate the internal pressure caused by fluctuations in the topcoat adhesive coating or bonding extrusion, promotes the uniformity of the encapsulation layer thickness, and improves the encapsulation reliability. Attached Figure Description

[0019] Figure 1 This is a top view schematic diagram of the current cover plate encapsulation structure for silicon-based OLEDs;

[0020] Figure 2 This is a cross-sectional schematic diagram of the current cover plate encapsulation structure for silicon-based OLEDs;

[0021] Figure 3 This is a three-dimensional structural diagram of a cover plate encapsulation structure for a silicon-based OLED proposed in this invention;

[0022] Figure 4 This is a schematic diagram showing the disassembled structure of a cover plate encapsulation structure for a silicon-based OLED proposed in this invention.

[0023] Figure 5 This is a top view schematic diagram of a cover plate encapsulation structure for a silicon-based OLED proposed in this invention;

[0024] Figure 6 This is a schematic cross-sectional view of the cover plate encapsulation structure of a silicon-based OLED proposed in this invention.

[0025] Figure 7 This is a top view of the enclosure structure of a cover plate encapsulation structure for a silicon-based OLED proposed in this invention.

[0026] Figure 8 This is a schematic cross-sectional view of the enclosure of a cover plate encapsulation structure for a silicon-based OLED proposed in this invention.

[0027] Figure 9 This is a schematic cross-sectional view of the cover plate encapsulation structure of a silicon-based OLED proposed in this invention after the application of the cofferdam adhesive and the surface adhesive.

[0028] Figure 10 This invention proposes a cover plate encapsulation structure for a silicon-based OLED. Figure 4 Enlarged structural diagram at point A in the middle.

[0029] In the diagram: 1. Silicon substrate; 2. Cover glass; 3. Dike adhesive; 4. Surface adhesive; 5. Display area; 6. Spacer; 101. First wall; 102. Second wall; 103. Buffer interlayer; 201. Overflow channel; 301. Guide section; 302. Drainage section; 401. Slope. Detailed Implementation

[0030] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0031] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Example 1

[0034] like Figures 1-10 As shown, a cover plate encapsulation structure for a silicon-based OLED includes a silicon substrate 1, a cover glass 2, a cofferdam adhesive 3, and a surface adhesive 4. The silicon substrate 1 is provided with a display area 5, and an isolation structure for isolating the cofferdam adhesive 3 and the surface adhesive 4.

[0035] The isolation structure includes a first wall 101 and a second wall 102 disposed on a silicon substrate 1. The first wall 101 is located outside the second wall 102, and a buffer interlayer 103 is formed between the two. The second wall 102 is disposed around the display area 5. A confining adhesive 3 is applied to the outside of the first wall 101. A surface adhesive 4 is applied to the display area 5 and contacts the inner wall of the second wall 102. An overflow assembly is disposed on the second wall 102.

[0036] Among them, the overflow component allows excess adhesive 4 in the display area 5 to pass through and flow into the buffer interlayer 103 during the pressing process of the cover glass 2.

[0037] An isolation structure consisting of a first wall 101 and a second wall 102 is formed on the silicon substrate 1, with a buffer layer 103 between them. The first wall 101 mainly contacts the cofferdam adhesive 3, while the second wall 102 provides a stable and precise inner boundary for the surface adhesive 4. During the encapsulation process, the exposure transmittance of the first wall 101 and the second wall 102 can be controlled by a single photomask, and they can be formed in one step using photolithography processes such as coating, exposure, and development. The width of the two walls can be set to 3.5 μm, and the spacing can be set to 100 μm. When the cover glass 2 is pressed together, the overflow component on the second wall 102 provides a preset overflow channel for excess surface adhesive 4 in the display area 5, allowing it to flow into the buffer layer 103 in an orderly manner, rather than dissolving with the cofferdam adhesive 3 or causing uncontrollable compression. The physical structure isolates the cofferdam adhesive 3 and the topcoat adhesive 4, resolving their mutual solubility before curing. Simultaneously, since the coating boundary of the topcoat adhesive 4 is defined by the second wall 102 formed by the photolithography process, rather than by the cofferdam adhesive 3 with lower coating precision, the stringent requirements for the precision of the topcoat adhesive coating equipment are significantly reduced, improving process tolerance and encapsulation yield. The entire cover plate bonding process follows the flow of cofferdam adhesive coating, topcoat adhesive coating, cover plate vacuum bonding, photocuring, and thermal curing.

[0038] Example 2

[0039] This embodiment further defines the overflow component based on embodiment 1.

[0040] like Figures 4-10 As shown, in this embodiment, the overflow component includes a plurality of overflow channels 201 opened on the second enclosure 102, and the overflow channels 201 are used to connect the display area 5 and the buffer interlayer 103.

[0041] like Figure 6 and Figures 8-10 As shown, in this embodiment, the overflow trough 201 consists of a flow guide 301 and a flow diversion 302.

[0042] like Figure 6 and Figures 8-10 As shown, in this embodiment, the flow guide 301 is an inclined surface that slopes from the middle of the overflow channel 201 toward the display area 5, and the flow diversion 302 is a straight channel connecting the highest point of the flow guide 301 with the buffer interlayer 103.

[0043] After the top adhesive 4 is applied and during the initial pressing of the cover glass 2, if there is too much top adhesive, the liquid will first overflow the inclined surface of the guide section 301, and then be smoothly introduced into the buffer interlayer 103 through the channel of the drainage section 302. This transforms the overflow process from passive, random squeezing to active, directional guidance. The technical effect is that it further refines and optimizes the path and control method of the top adhesive overflow, avoiding local pressure accumulation of the adhesive within narrow interfaces, ensuring the uniformity of the encapsulation layer thickness, and achieving a uniform encapsulation effect even when there are certain fluctuations in the top adhesive coating. This overflow groove 201 structure can be formed simultaneously during the photolithography process for fabricating the second enclosure 102.

[0044] Example 3

[0045] This embodiment optimizes the buffer interlayer 103 based on embodiments 1 and 2.

[0046] like Figure 6 and Figures 8-9 As shown, in this embodiment, a ramp 401 is provided in the buffer interlayer 103, and the ramp 401 has an inclined slope toward the root of the first wall 101.

[0047] Excess adhesive 4 flowing from the overflow component into the buffer interlayer 103 will, under the influence of gravity and liquid surface tension, flow along the inclined surface of the ramp 401 and accumulate at the root region of the first enclosure 101. This ramp 401 structure actively manages the adhesive distribution within the buffer interlayer 103, preventing disorderly spread of the adhesive. The adhesive accumulated at the root forms a continuous, surrounding auxiliary sealing ring, which is equivalent to adding a redundant anti-permeability barrier to the inner side of the root of the main sealing barrier, i.e., the first enclosure 101. This significantly enhances the packaging structure's resistance to water and oxygen intrusion, especially lateral path intrusion, and improves the long-term reliability of the device. This ramp 401 structure can be implemented simultaneously during the photolithography fabrication of the enclosure.

[0048] Example 4

[0049] This embodiment, based on embodiment 1, further defines the wall material and its dynamic behavior.

[0050] like Figures 1-10 As shown, in this embodiment, both the first enclosure 101 and the second enclosure 102 are made of elastic plastic material. The second enclosure 102 deforms when the cover glass 2 is pressed together and closes the flow channel after the excess adhesive 4 passes through the overflow groove 201.

[0051] During the pressing of the cover glass 2, the second enclosure 102 undergoes elastic deformation. After pressing is completed and excess colloid is discharged, the deformation of the second enclosure 102 narrows or even closes the flow channel of the overflow groove 201. The enclosure material is usually a negative photosensitive material (such as acrylic copolymer), which needs to have a high elastic modulus and be able to produce controllable plastic deformation under pressure. This achieves "process opening and final closure" of the overflow channel. It ensures the pressure release function during the process and reduces potential permeation paths formed by open trenches after encapsulation, so that the overflow component does not affect the long-term airtightness of the encapsulation after completing its flow guiding function, achieving a balance between functionality and reliability.

[0052] Example 5

[0053] This embodiment, based on embodiment 1, further limits the height of the wall and the structure of the cofferdam.

[0054] like Figure 3 , Figure 6 and Figures 8-10 As shown, in this embodiment, the height of the first wall 101 is greater than the height of the second wall 102.

[0055] like Figure 6 and Figure 9 As shown, in this embodiment, the cofferdam adhesive 3 contains a spacer 6, and the initial height of the spacer 6 matches the initial height of the first wall 101.

[0056] During the atmospheric compression stage after vacuum bonding, the cover glass 2 simultaneously presses down on the spacer 6 and the first enclosure 101 in the cofferdam adhesive 3. Since both have similar initial heights (e.g., both can be set to 4μm) and are compressible (spacer 6 is a resin ball), they undergo essentially equal compression deformation together, providing initial support. Only when the compression reaches the height level of the second enclosure 102 does the cover glass 2 contact the top of the second enclosure 102. This height difference design ensures that the adhesive 4 overflows before the cover glass 2 contacts the second enclosure 102, preventing premature sealing. The coordinated compression of the spacer 6 and the first enclosure 101 provides uniform and stable support for the cover glass 2, avoiding poor bonding or stress concentration caused by uneven local support, ensuring the uniformity of the display area cavity, and thus guaranteeing the consistency of optical performance and the mechanical stability of the encapsulation structure. The doping of the septum 6 can be mixed before the coating of the cofferdam adhesive 3. Its size must match the design. The height difference between the first wall 101 and the second wall 102 can also be adjusted according to the actual product requirements.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A cover glass encapsulation structure for a silicon-based OLED, comprising a silicon substrate (1), a cover glass (2), a cofferdam adhesive (3), and a surface adhesive (4), characterized in that: The silicon substrate (1) is provided with a display area (5) and an isolation structure for isolating the cofferdam adhesive (3) and the surface adhesive (4); The isolation structure includes a first wall (101) and a second wall (102) disposed on a silicon substrate (1). The first wall (101) is located outside the second wall (102), and a buffer interlayer (103) is formed between the two. The second wall (102) is disposed around the display area (5). A dam adhesive (3) is applied to the outside of the first wall (101). A surface adhesive (4) is applied to the display area (5) and contacts the inner wall of the second wall (102). An overflow assembly is disposed on the second wall (102). During the pressing process of the cover glass (2), the overflow component allows excess adhesive (4) in the display area (5) to pass through and flow into the buffer interlayer (103).

2. The cover plate encapsulation structure for a silicon-based OLED according to claim 1, characterized in that, The overflow assembly includes multiple overflow channels (201) opened on the second wall (102), the overflow channels (201) being used to connect the display area (5) and the buffer interlayer (103).

3. The cover plate encapsulation structure for a silicon-based OLED according to claim 2, characterized in that, The overflow trough (201) consists of a flow guide (301) and a flow diversion section (302).

4. The cover plate encapsulation structure for a silicon-based OLED according to claim 3, characterized in that, The flow guide (301) is an inclined surface that slopes from the middle of the overflow channel (201) toward the display area (5), and the flow diversion part (302) is a straight channel connecting the highest point of the flow guide (301) with the buffer interlayer (103).

5. The cover plate encapsulation structure for a silicon-based OLED according to claim 1, characterized in that, The buffer interlayer (103) is provided with a ramp (401) having an inclined slope toward the root of the first wall (101).

6. The cover plate encapsulation structure for a silicon-based OLED according to claim 1, characterized in that, The first enclosure (101) and the second enclosure (102) are both made of elastic plastic material. The second enclosure (102) deforms when the cover glass (2) is pressed together and closes the flow channel after the excess adhesive (4) passes through the overflow channel (201).

7. The cover plate encapsulation structure for a silicon-based OLED according to claim 6, characterized in that, The height of the first wall (101) is greater than the height of the second wall (102).

8. The cover plate encapsulation structure for a silicon-based OLED according to claim 1, characterized in that, The cofferdam adhesive (3) contains a septum (6), the initial height of which matches the initial height of the first wall (101).

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