Miniature LED module packaging structure, preparation method and display device

Abstract

The invention discloses a miniature LED module packaging structure, a preparation method and a display device, and relates to the technical field of micro display, and the miniature LED module packaging structure comprises a substrate, a driving chip, an LED chip and a protection shell. The substrate comprises a patch area and a bonding wire area; the driving chip is mounted in the chip mounting area and is electrically connected with the wire welding area through a lead; the LED chip is bonded on the driving chip and is driven by the driving chip to emit light; the protection shell is attached to the substrate, and the protection shell, the substrate and the driving chip define a protection cavity used for containing the lead. The lead is covered and protected by the protective shell, and the flatness and the appearance consistency of the protective shell are high, so that the problem that the appearance consistency of the existing glue-sealed lead is poor is solved, and the subsequent module assembly is facilitated. Meanwhile, the packaging structure also solves the problem that the size of the module is too large due to the fact that the glue thickness is large and the glue diffusion area is large in the existing COB packaging process, so that the requirement for module miniaturization is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro display, in particular to a micro LED module packaging structure, a packaging method and a display device. BACKGROUND

[0002] With the rapid development of virtual reality (VR) and augmented reality (AR) technology, the requirements for display technology are constantly improving. Micro-LED display technology has emerged as a result of its high brightness, high resolution and pixel density. Its modular design can be flexibly spliced into screens of different sizes to meet the needs of various devices. Currently, traditional Micro-LED module packaging often adopts Chip on board (COB) method, which covers die bonding, cleaning, wire bonding, gold wire encapsulation and other processes. For example, the chip is first bonded to the FPC board and baked to solidify, then cleaned and wire bonded, and finally the gold wire dam glue and filling glue are coated and cured to protect the gold wire.

[0003] However, the existing COB packaging method for protecting gold wires has inconsistent wire bonding arc heights, and the glue flow during encapsulation makes it difficult to accurately control the glue shape. In addition, the glue curing relies on UV light and heat baking, and the curing speed of glue at different positions also differs, resulting in poor consistency of the final Micro-LED module shape, which affects subsequent module assembly. At the same time, the Micro LED module formed by COB packaging has the problem of large volume due to high glue thickness and large glue diffusion area. SUMMARY

[0004] The main purpose of the present application is to provide a micro LED module packaging structure, a packaging method and a display device, which aims to solve the problems of poor consistency of the existing micro LED module packaging structure and large module volume.

[0005] To achieve the above-mentioned purpose, the micro LED module packaging structure provided by the present application comprises: a substrate, the substrate comprising a patch area and a wire bonding area; a driving chip, the driving chip being mounted on the patch area and being electrically connected to the wire bonding area through a lead; an LED chip, the LED chip being bonded to the driving chip and emitting light under the driving of the driving chip; and a protective shell, the protective shell being mounted on the substrate and enclosing the substrate and the driving chip to form a protective cavity for accommodating the lead.

[0006] In an embodiment of the present application, the protective shell is arranged on the driving chip and the wire bonding area, and is bonded to the substrate through a glue layer, the protective shell is provided with a clearance, and the clearance has a size greater than or equal to the size of the LED chip to expose the LED chip.

[0007] In an embodiment of the present application, the protective shell comprises a cover plate, a frame arranged on the surface of the cover plate, and a support block, the frame is arranged around the periphery of the surface of the cover plate on the side facing the LED chip and is connected to the substrate, and the support block abuts the surface of the driving chip.

[0008] In an embodiment of the present application, the support block is arranged on the side close to the driving chip and the lead wire, and extends along the side close to the lead wire of the driving chip, and the support block, at least part of the frame, at least part of the cover plate, the substrate, and the driving chip form a protective cavity.

[0009] In an embodiment of the present application, the cover plate abuts at least part of the surface of the driving chip away from the lead wire.

[0010] In an embodiment of the present application, the support block extends along the periphery of the clearance to form an annular support structure.

[0011] In an embodiment of the present application, the protective shell is an integrally formed structure made of injection molding or 3D printing.

[0012] In an embodiment of the present application, the surface of the protective shell facing the substrate is provided with a glue containing groove, the glue containing groove extends along the periphery of the protective shell and surrounds the outer periphery of the driving chip and the wire bonding area.

[0013] In an embodiment of the present application, the height difference between the highest point of the lead wire and the top wall of the protective cavity is H, and 25um≤H≤75um. And / or, the shortest distance between the LED chip and the edge of the substrate is D, and 200um≤D≤400um.

[0014] In an embodiment of the present application, the micro-LED module packaging structure further comprises a heat sink, the substrate is a flexible circuit board, the heat sink is arranged on the side of the substrate away from the protective shell, and the projection of the protective shell on the surface of the substrate is located in the projection area of the heat sink on the surface of the substrate.

[0015] In an embodiment of the present application, the surface of the protective shell away from the substrate is parallel to the light emitting surface of the LED chip.

[0016] The present invention also provides a method for preparing a micro LED module packaging structure, the method comprising the steps of: Bonding the driver chip and the LED chip to form a light-emitting device; Dispensing glue on the surface of the patch area of ​​the substrate, and attaching the light-emitting device to the patch area; electrically connecting the driver chip to the bonding area of ​​the substrate through the lead wire; Glue is dispensed on the surface of the substrate, and the protective shell is attached to the surface of the substrate and covers the leads and the wire bonding area.

[0017] The present invention further provides a display device, comprising an optical engine and any of the above-described micro-LED module packaging structures; The optical engine is packaged on the micro LED module packaging structure and is located on the light-emitting side of the LED chip.

[0018] In one embodiment of the present invention, the protective shell is provided with an escape opening, the LED chip is exposed in the escape opening, the optical engine is arranged on the protective shell and blocks the escape opening, and the optical engine and the protective shell are sealed and connected by a sealant.

[0019] The micro-LED module packaging structure proposed in this invention includes a substrate, a driver chip, an LED chip, and a protective shell. The substrate includes a mounting area and a wire bonding area. The wire bonding area is provided with pads and electronic components. The driver chip is mounted on the mounting area, and metal leads are connected to the driver chip and the pads in the wire bonding area to achieve an electrical connection between the driver chip and the substrate. The LED chip is bonded to the driver chip, and then the LED chip is driven by the driver chip to emit light.

[0020] The protective shell is mounted on the substrate, and the protective shell cover is arranged above the lead, and is enclosed with the substrate and the driver chip to form a protective cavity. The lead is in the protective cavity so that the protective shell plays a protective role on the lead. The protective shell can be made by injection molding or 3D printing and other processes to ensure that the size and shape of the protective shell are uniform, thereby making the formed micro-LED module packaging structure have a high consistency in appearance, which is convenient for the subsequent assembly of the module. At the same time, since the packaging structure of the present application protects the lead through the protective shell, there is no need to set gold wire filling glue, which solves the problem of large module volume caused by high glue thickness and large glue diffusion area in the existing COB packaging, so as to meet the demand for module miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from the structures shown in the drawings without any creative effort.

[0022] Figure 1 Structure diagram of the substrate in the micro-LED module packaging structure provided by the present application; Figure 2 Structure diagram of the driving chip, LED chip and substrate packaging in the micro-LED module packaging structure provided by the present application; Figure 3 Structure diagram of the driving chip and substrate connected by the lead in the micro-LED module packaging structure provided by the present application; Figure 4 Structure diagram of the protective shell in the micro-LED module packaging structure provided by the present application; Figure 5 Structure diagram of the protective shell and driving chip, LED chip and substrate packaging in the micro-LED module packaging structure provided by the present application; Figure 6 Internal structure diagram of the micro-LED module packaging structure provided by the present application; Figure 7 Internal structure diagram of the light machine and the micro-LED module packaging structure after packaging; Figure 8 Flow chart of the preparation method of the micro-LED module packaging structure provided by the present application.

[0023] Explanation of the reference numerals: 10, substrate; 11, soldering area; 12, patch area; 13, electronic component; 20, driving chip; 30, LED chip; 40, lead; 50, protective shell; 51, cover plate; 52, frame; 53, support block; 54, avoiding opening; 55, protective cavity; 56, glue containing groove; 60, light machine; 70, heat dissipation plate; 80, connector; 90, metal shielding cover.

[0024] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0025] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present application.

[0026] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture, and if the certain posture changes, the directional indications will also change accordingly.

[0027] In addition, if the embodiments of the present application involve descriptions such as “first”, “second”, etc., the descriptions of “first”, “second”, etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first” and “second” can explicitly or implicitly include at least one of the features. In addition, “and / or” or “and / or” appearing throughout the text means that the three parallel schemes are included, for example, “A and / or B” includes A scheme, or B scheme, or A and B are satisfied at the same time. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0028] In the prior art, the packaging process of the micro LED module usually uses liquid glue to protect the lead. Due to the difference in the arc height of the soldering wire, it is difficult for the glue to form uniform coverage during flow, and the glue type is difficult to control accurately. The difference in UV light or heat baking during solidification further aggravates the structural deformation, making it difficult to achieve accurate alignment during module assembly, affecting the overall performance of the display device. In addition, due to the different distances from the curing source, the curing speed is different, so the glue type of the Micro LED module at different positions, or the glue type of the Micro LED module at different positions of the carrier simultaneously cured will be different, resulting in poor consistency of the appearance of the COB packaged Micro LED module. And the packaging process needs to be carried out three times of dispensing and curing (three times of dispensing are dispensing glue for fixing the chip, gold wire dam glue, and gold wire filling glue), resulting in low production efficiency. In addition, the resin glue used for gold wire sealing has low pressure resistance and poor mechanical properties. Some existing packaging processes utilize plastic encapsulation to protect the leads. These processes heat solid epoxy molding compound (EMC) to a molten state using an injection molding machine. The wire-bonded Micro LED modules are then neatly arranged in a custom carrier and placed into a dedicated mold. The molds are then closed and molten resin is injected. Once the resin solidifies, it encapsulates the gold wires and substrate, completing the injection molding process. While this packaging method can improve module appearance consistency, the high cost of the injection molding machine and molds limits its large-scale application.

[0029] In order to solve the above problems, the present invention proposes a micro LED module packaging structure.

[0030] Combine Figures 1 to 3 as well as Figure 5 and Figure 6 As shown, in one embodiment of the present invention, the micro LED module packaging structure includes a substrate 10, a driver chip 20, an LED chip 30 and a protective shell 50; the substrate 10 includes a patch area 12 and a wire bonding area 11; the driver chip 20 is mounted on the patch area 12 and is electrically connected to the wire bonding area 11 through a lead 40; the LED chip 30 is bonded to the driver chip 20 and emits light under the drive of the driver chip 20; the protective shell 50 is mounted on the substrate 10, and encloses the substrate 10 and the driver chip 20 to form a protective cavity 55 for accommodating the lead 40.

[0031] The substrate 10 can be a flexible printed circuit board (FPC), a rigid printed circuit board (PCB), or a flexible and rigid combined board PCB-FPC. The patch area 12 on its surface is used for chip mounting and positioning. The wire bonding area 11 provides electrical connection pads. The pads of the wire bonding area 11 are connected to the pads on the surface of the driver chip 20 by welding through the lead 40 to achieve the connection between the driver chip 20 and the circuit of the substrate 10. The lead 40 can be a gold wire or a copper wire. In addition, Figure 1 As shown, electronic components 13, such as capacitors, resistors, ferrite beads, ASICs, and connectors, are also disposed on the surface of substrate 10. A metal shield 90 is disposed above these electronic components 13 to reduce interference from external signals. A connector 80 is disposed on one side of substrate 10. Connector 80 is used to electrically connect substrate 10 to an external power supply device and to communicate with an external control device.

[0032] The driver chip 20 is provided with an integrated circuit for driving the LED to emit light. Specifically, the LED chip 30 can be mounted on the driver chip 20 in the form of bonding, that is, under the conditions of hot pressing or hot pressing + ultrasonic waves, the metal bumps and the pads are mechanically connected and electrically conductive to minimize the overall volume.

[0033] The protective shell 50 refers to a preformed component covering the surface of the substrate 10, which can specifically be a plastic shell formed by injection molding, and the inner wall of the protective shell 50 cooperates with the substrate 10 and the driving chip 20 to form a protective cavity 55, so that the lead wire 40 is isolated from the external environment, and the lead wire 40 is prevented from being broken due to mechanical impact or moisture corrosion, thereby improving the reliability of the lead wire 40. The protective shell 50 is fixed on the substrate 10 by means of sealing glue, so as to improve the stability of the protective shell 50. Here, the sealing glue is used to fixedly connect the protective shell 50 and the substrate 10, and does not serve the purpose of forming a dam or filling gold wires, and the thickness and amount of the sealing glue are relatively low, the glue dispensing speed is relatively fast, and the influence on the overall module appearance consistency is also relatively small.

[0034] Specifically, as shown in Figure 6 The protective shell 50 is fixedly connected with the substrate 10 and forms the protective cavity 55, and the protective cavity 55 wraps the lead wire 40 structure. The spatial size and structural shape of the protective shell 50 are determined before assembly, so as to avoid the size deviation caused by the solidification shrinkage or expansion of the liquid glue. Therefore, the present scheme constructs a stable protection space for the lead wire 40 by preforming the protective shell 50. Meanwhile, compared with the prior art which needs to dispense and solidify the glue on the lead wire 40 twice, the present scheme can complete the packaging and protection of the lead wire 40 by means of one-time pasting of the protective shell 50, thereby improving the production efficiency. In addition, since the region of the packaged lead wire 40 is a hollow structure, if it is found that the signal conduction is poor after the protective shell 50 is pasted, the protective shell 50 can be removed and the gold wire can be reworked, thereby improving the yield.

[0035] As shown in Figures 4 to 6 In an embodiment of the present application, the protective shell 50 covers the driving chip 20 and the soldering wire area 11, and is bonded with the substrate 10 through a glue layer. The protective shell 50 is provided with a relief opening 54, and the size of the relief opening 54 is greater than or equal to the size of the LED chip 30, so as to expose the LED chip 30.

[0036] In the present embodiment, the protective shell 50 covers the soldering wire area 11 domain where the driving chip 20 is connected with the substrate 10, so that the protective shell 50 not only plays a protective role on the lead wire 40, but also plays a protective role on the driving chip 20, so as to protect the driving chip 20 from mechanical impact during module packaging. The protective shell 50 is bonded with the substrate 10 through a glue layer, so as to fix the protective shell 50; the protective shell 50 and the driving chip 20 can be in abutment, gap fit or bonded through a glue layer.

[0037] The relief opening 54 is formed on the surface of the protective shell 50, which can be realized by laser cutting or mold forming. The opening size of the relief opening 54 matches the size of the LED chip 30, and the relief opening 54 corresponds to the LED chip 30, so that the light emitted by the LED chip 30 can be emitted through the relief opening 54.

[0038] In other embodiments, the protective shell 50 may be provided only around the periphery of the leads 40. In another embodiment, the protective shell 50 may be provided to be at least partially transparent and to cover the periphery of the LED chip 30, the driver chip 20, the wire bonding area 11, and the leads 40, with the LED chip 30 aligned with the transparent area of ​​the protective shell 50.

[0039] Combine Figure 4 and Figure 6 As shown, in one embodiment of the present invention, the protective shell 50 includes a cover plate 51 and a frame 52 and a support block 53 provided on the surface of the cover plate 51. The frame 52 is arranged around the periphery of the surface of the cover plate 51 facing the LED chip 30 and is connected to the substrate 10. The support block 53 abuts the surface of the driver chip 20.

[0040] In this embodiment, the cover plate 51 is a flat plate structure covering the substrate 10, and is used to form the top sealing surface of the protective cavity 55, that is, the top structure of the protective shell 50. The frame 52 is arranged on the side of the cover plate 51 facing the substrate 10, and extends along the periphery of the cover plate 51 to form a frame structure surrounding the lead 40, or the driver chip 20 and the lead 40, and forms the side wall of the protective cavity 55, that is, the side structure of the protective shell 50. The support block 53 is a columnar protrusion arranged between the cover plate 51 and the driver chip 20, and is used to form a mechanical support between the cover plate 51 and the driver chip 20, that is, the internal support structure of the protective shell 50. The support block 53 can be set at any position on the surface of the driver chip 20 that avoids the connection area with the lead 40 and the bonding area with the LED chip 30.

[0041] Specifically, the frame 52 and substrate 10 are sealed together with a sealant, and the support block 53 abuts the surface of the driver chip 20. Therefore, the frame and support block jointly support the cover plate 51, thereby improving the structural stability of the protective shell 50. The support block 53, frame 52, cover plate 51, substrate 10, and driver chip 20 enclose the protective cavity 55. The multi-point support of the support block 53 and frame 52 improves the structural stability of the protective cavity 55, thereby preventing the protective cavity 55 from deforming due to external forces and colliding with the leads 40, thereby improving the protection of the leads 40 and also improving the appearance consistency of the encapsulated micro LED module.

[0042] In one embodiment of the present invention, the protective shell 50 is an integrally formed structure made by injection molding or 3D printing.

[0043] In the packaging process, the protective shell 50 is directly pressed on the surface of the substrate 10 as a prefabricated component, the internal support block 53 mechanically limits the driving chip 20, and the protective cavity 55 is spatially isolated from the lead 40. Since the protective shell 50 is an integral structure, the cover plate 51, the surrounding frame 52, and the support block 53 have the same thermal expansion coefficient, and the overall structure will not locally warp during the packaging process, thereby maintaining the constant spacing between the top wall of the protective cavity 55 and the lead 40 and the consistency of the shape of the protective shell 50. At the same time, the cover plate 51, the surrounding frame 52, and the support block 53 are integrally formed, and the size control is more accurate than the split connection structure, and the flatness is higher, further improving the module packaging precision and the consistency of the module shape.

[0044] Compared with the original need for multiple coating of the glue layer to cover the lead 40, the present application can protect the lead 40 through one-time packaging of the preformed protective shell 50, eliminating the uncertainty of the glue flow path, improving the production efficiency, and avoiding the solidification deformation caused by the difference in thermal expansion of multiple components.

[0045] In combination Figure 6 As shown in the embodiment of the present application, the support block 53 is arranged on the side close to the driving chip 20 where the lead 40 is connected, and extends along the side of the driving chip 20 close to the lead 40.

[0046] The support block 53 is a local protruding structure arranged between the cover plate 51 and the driving chip 20, which is used to abut against the driving chip 20 at a specific position and support the cover plate 51, so as to form a protective cavity 55 with stable structure. In this embodiment, the support block 53 is arranged on the side close to the lead 40 where the lead 40 is connected, so that it can form directional support for the dense area of the lead 40 and avoid the protective shell 50 from being deformed by external force and hitting the lead 40. Since the pads of the driving chip 20 are generally arranged close to one side, for example Figure 5 As shown, the pads on the driving chip 20 connected with the lead 40 are arranged close to the lower side, and a plurality of pads are arranged in sequence along the lower side. Therefore, in this embodiment, the support block 53 is arranged along the side of the driving chip 20 where the lead 40 is connected (i.e. the above-mentioned lower side), so as to improve the protection effect of the lead 40. And the support block 53 extends along the side of the driving chip 20 close to the lead 40 (i.e. the above-mentioned lower side), further improving the contact area between the support block 53 and the driving chip 20.

[0047] Since the extension direction of the support block 53 is consistent with the arrangement direction of the lead 40, this layout not only prevents the protective shell 50 from being deformed by gravity or assembly pressure and pressing the lead 40, thereby maintaining the stability of the internal structure of the protective cavity 55, but also avoids the interference of the support structure extending transversely with the lead 40 welding space.

[0048] The support block 53 and the driver chip 20 may be in abutment, clearance fit, or fixedly connected by an adhesive. The support block 53 may be disposed close to the edge of the escape opening 54 to increase the space of the protection cavity 55.

[0049] Combine Figure 6 As shown, in one embodiment of the present invention, the cover plate 51 is in contact with at least a portion of the surface of the driver chip 20 away from the leads 40 .

[0050] As can be seen from the above, the support block 53 abuts against the surface of the driver chip 20 close to the lead 40, and supports the cover plate 51 so that the cover plate 51, the driver chip 20, the substrate 10, the frame 52 and the support block 53 form a protective cavity 55. In this embodiment, the cover plate 51 abuts against at least the portion of the surface of the driver chip 20 away from the lead 40, as shown in FIG. Figure 6 As shown, for example, the thickness of the cover plate 51 at a position away from the lead 40 is designed to be greater than the thickness near the lead 40 (ie Figure 6 The thickness of the cover plate 51 on the left side of the middle avoidance opening 54 is greater than the thickness of the cover plate 51 on the right side of the avoidance opening 54), so that the cover plate 51 contacts the surface of the driver chip 20 away from the lead 40, thereby improving the stability and flatness of the cover plate 51.

[0051] Of course, the cover plate 51 can also be arranged so that three sides thereof abut against the driver chip 20, and one side abuts against the driver chip 20 through the support block 53. Figure 5 As shown, the side of the driver chip 20 connected to the lead 40 is defined as the lower side, the side corresponding to the lower side is the upper side, and the other two sides are the right side and the left side respectively. At this time, the thickness of the cover plate 51 and the upper side, left side and right side of the driver chip 20 is designed to be larger, and the thickness of the cover plate 51 corresponding to the lower side of the driver chip 20 is designed to be smaller, and the support block 53 is correspondingly arranged on the lower side of the driver chip 20. At this time, when the protective shell 50 is encapsulated on the substrate 10, the support block 53 is fitted and abutted against the lower side of the driver chip 20, and the cover plate 51 is fitted and abutted against the upper side, left side and right side of the driver chip 20 respectively, that is, the protective shell 50 forms a stable support structure for the driver chip 20 on all sides of the LED chip 30, thereby making the protective shell 50 not only more stable in the structure around the lead 40, but also more stable in the structure around the LED chip 30, thereby making the flatness of the protective shell 50 facing away from the substrate 10 higher. The cover plate 51 and the support block 53 may abut against the surface of the driver chip 20 , or may be connected to the driver chip 20 via an adhesive.

[0052] Since the micro-LED module package structure needs to be assembled with the light machine 60 subsequently, the light machine 60 is located on the light-emitting side of the LED chip 30, therefore, the structure design of the embodiment can facilitate the installation of the light machine 60 on the surface of the protective shell 50 and above the avoiding opening 54, and the light machine 60 is supported by the cover plate 51 of the protective shell 50. Since the protective shell 50 around the LED chip 30 has a relatively stable structure, high flatness and high shape consistency, the installation precision of the light machine 60 can be improved, and thus the display effect is improved.

[0053] In an embodiment of the present application, the support block 53 extends along the periphery of the avoiding opening 54 to form a ring-shaped support structure.

[0054] In the embodiment, the support block 53 is designed in a circular ring shape or a square shape to form a support structure continuously distributed around the outer edge of the LED chip 30, which can be formed by an integral molding process such as injection molding or 3D printing. The inner circle contour of the support block 53 is kept at a distance from the edge of the LED chip 30 to facilitate packaging.

[0055] When an external force is applied to the surface of the protective shell 50, the support structure and the surrounding frame 52 evenly disperse the pressure along the ring-shaped or square-shaped path to the surface of the driving chip 20 and the surface of the substrate 10, avoiding stress concentration in the local area to cause the protective shell 50 to break, deform or displace, thereby improving the protection effect on the lead wire 40 and the consistency of the shape of the protective shell 50.

[0056] In combination with Figure 4 As shown in the figure, in an embodiment of the present application, the surface of the protective shell 50 facing the substrate 10 is provided with a glue containing groove 56, which extends along the periphery of the protective shell 50 and surrounds the outer periphery of the driving chip 20 and the soldering area 11.

[0057] In the embodiment, the protective shell 50 and the substrate 10 are connected by sealing glue, and the glue containing groove 56 is opened on the surface of the protective shell 50 facing the substrate 10. When the protective shell 50 is attached to the substrate 10, a certain amount of flowing sealing glue will enter the glue containing groove 56, thereby increasing the contact area between the sealing glue and the protective shell 50, and improving the connection strength between the protective shell 50 and the substrate 10. At the same time, the sealing glue filled in the glue containing groove 56 also improves the sealing effect between the substrate 10 and the protective shell 50, reduces the moisture and dust entering the connection between the substrate 10 and the protective shell 50 or the protective cavity 55, and thus improves the packaging reliability of the substrate 10 and the protective shell 50, the sealing performance of the protective cavity 55, and the reliability of the connection between the lead wire 40 and the driving chip 20 and the substrate 10.

[0058] In an embodiment of the present application, the height difference between the highest point of the lead wire 40 and the top wall of the protective cavity 55 is H, and 25um≤H≤75um. And / or, the shortest distance between the LED chip 30 and the edge of the substrate 10 is D, 200um≤D≤400um.

[0059] In the embodiment, the height difference between the highest point of the lead 40 and the top wall of the protection cavity 55 refers to the distance between the upper surface of the highest lead 40 and the top inner wall of the protection cavity 55 in the vertical direction. Due to the process influence, the arc height of the lead 40 will have a certain floating. In addition, the size deviation of the protection shell 50 and the glue thickness deviation between the protection shell 50 and the substrate 10 will also affect the height difference between the highest point of the lead 40 and the top wall of the protection cavity 55. Therefore, the height difference H is designed to be 25um≤H≤75um. This parameter range can avoid the deformation or fracture of the lead 40 caused by the downward pressure of the top wall of the protection cavity 55, and at the same time, the overall thickness of the module is reduced as much as possible to meet the miniaturization requirement. The height difference H can be 30um, 40um, 50um, 60um or 70um.

[0060] In the case of limiting or not limiting the height difference between the lead 40 and the top wall of the protection cavity 55, the shortest distance between the LED chip 30 and the edge of the substrate 10 refers to the minimum horizontal distance from the chip edge to the outer contour of the substrate 10. This parameter range can reduce the area occupation of the substrate 10 while meeting the requirements of the surface circuit layout of the substrate 10 and the packaging space of the protection shell 50, thereby increasing the number of chips produced by a single wafer on the same size specification wafer.

[0061] The shortest distance D between the LED chip 30 and the edge of the substrate 10 can be 200um, 300um or 400um. Relative to the plastic packaging process, due to the width of the mold itself (300um) of the plastic packaging process, the injection resin needs to wrap about 200um outside the chip, and the mold needs to maintain a safe distance (about 100um) from the LED chip 30 during the injection process. Therefore, the plastic packaging process needs to meet the requirement that the minimum distance from the LED chip 30 to the surface of the substrate 10 is greater than or equal to 600um. Therefore, the size of the micro-LED module packaging structure can be reduced by the present application relative to the plastic packaging process, the number of chips produced by a single wafer is increased, and the unit manufacturing cost is reduced.

[0062] In combination with Figures 1 to 3 As shown in the embodiment of the present application, the micro-LED module packaging structure further comprises a heat sink 70. The substrate 10 is a flexible circuit board. The heat sink 70 is arranged on the side of the substrate 10 away from the protection shell 50. The projection of the protection shell 50 on the surface of the substrate 10 is located in the projection area of the heat sink 70 on the surface of the substrate 10.

[0063] The heat dissipation plate 70 can be a metal plate or a ceramic plate, which is fixed to the surface of the substrate 10 by bonding or pressing, and is used to improve the bending resistance and heat dissipation capacity of the local area of the substrate 10. The projection area refers to the coverage range of the protective shell 50 on the surface of the substrate 10, which is completely contained in the support range of the heat dissipation plate 70, so as to ensure that the substrate 10 in the area where the protective shell 50 is located is uniformly supported by the heat dissipation plate 70, and the heat dissipation effect of the driving chip 20 and the LED chip 30 is improved.

[0064] Through the above technical solution, the deformation amount of the flexible substrate 10 in the packaging process is effectively inhibited, and the integrity of the lead wire 40 connection structure is maintained, thereby avoiding the displacement of the LED chip 30 or the breakage of the lead wire 40 caused by the deformation of the substrate 10, so as to improve the alignment accuracy and long-term reliability of the module in the subsequent assembly process.

[0065] In combination Figure 6 As shown in the embodiment of the present application, the surface of the protective shell 50 away from the substrate 10 is parallel to the light emitting surface of the LED chip 30.

[0066] The surface of the protective shell 50 can be controlled by injection molding or 3D printing integrated molding process, and the surface flatness can also be controlled by mechanical polishing, grinding and other processes after integrated molding. The surface serves as the reference surface for the installation of the optical machine 60, and the parallelism directly affects the consistency of the optical path transmission direction.

[0067] Specifically, as Figure 7 shown, during the assembly process of the packaging structure, when the outer surface of the protective shell 50 is parallel to the light emitting surface, the outer surface of the protective shell 50 can be directly used as a reference for alignment during the installation of the optical machine 60, so as to avoid the deviation of the optical path or the misalignment of the optical machine 60 components caused by the inclination of the packaging shell. The shapes of different LED module packaging structures tend to be consistent, thereby eliminating the shape deviation of the module caused by the difference in curing process or the flow of glue.

[0068] The present application also provides a preparation method of the micro-LED module packaging structure, as Figure 8 shown, the preparation method comprises the following steps: S10: bonding and connecting the driving chip 20 and the LED chip 30 to form a light emitting device; S20: dispensing glue on the surface of the patch area 12 of the substrate 10, and attaching the light emitting device to the patch area 12; S30: electrically connecting the driving chip 20 and the soldering area 11 of the substrate 10 through the lead wire 40; S40: dispensing glue on the surface of the substrate 10, attaching the protective shell 50 to the surface of the substrate 10, and covering the lead wire 40 and the soldering area 11.

[0069] The metal bump is arranged on the surface of the LED chip 30 or the driving chip 20, and the metal bump is bonded and connected with the bonding pad under the action of hot pressing and ultrasonic waves, so that the LED chip 30 and the driving chip 20 are electrically interconnected. Then, after dispensing glue on the patch area 12 of the substrate 10, the light emitting device is grabbed by a die bonding machine and accurately attached to the patch area 12. After the mounting is completed, the packaged module is placed in an oven for baking until the glue solidifies.

[0070] After the light emitting device is mounted, the packaged module is cleaned by plasma cleaning to clean the driving chip 20 and the wire bonding area 11 of the substrate 10, and the reliability and solderability of the lead wire 40 connection are improved. Then, the driving chip 20 and the lead wire 40 of the substrate 10 are connected by using a wire bonding machine, and signal conduction is realized.

[0071] Then, the glue is coated on the surface of the substrate 10 by using a dispensing machine, and the prefabricated protective shell 50 is accurately positioned and attached to the substrate 10 by using a die bonding machine, and the lead wire 40 and the wire bonding area 11 are covered in the protective cavity 55. The mounted module is placed in an oven for baking until the glue solidifies.

[0072] Due to the above preparation method, it is not necessary to arrange dam glue around the lead wire 40, and it is not necessary to arrange filling glue to fill and wrap the lead wire 40. Only once the protective shell 50 is attached, the protection purpose of the lead wire 40 can be achieved, and therefore the production efficiency is improved.

[0073] Although the glue is coated on the surface of the substrate 10 when the protective shell 50 is attached, the glue plays a connecting role, and the thickness is much smaller than the thickness of the dam glue in the prior art. The dispensing efficiency is also much higher than the dam glue forming efficiency in the prior art. At the same time, due to the small thickness of the glue, the influence on the flatness and shape consistency of the protective shell 50 is also small. In the prior art, the height of the dam glue is close to the height of the lead wire 40, and the thicker the glue type, the more difficult it is to control the flatness. The protective shell 50 of the present application is an integrally formed structure formed by an injection molding process or a 3D printing process, and therefore the surface flatness and shape consistency are greatly improved compared with the prior art COB packaging, and the accuracy of subsequent module packaging alignment (such as light machine 60 packaging) is improved. Secondly, compared with the plastic packaging process, not only the volume of the finished module is reduced, but also the high-cost mold and equipment cost is avoided, and the production cost is reduced.

[0074] The present application also provides a display device, which comprises a light machine 60 and a micro-LED module packaging structure. The specific structure of the micro-LED module packaging structure is referred to the above embodiments. Since the display device adopts all the technical solutions of the above micro-LED module packaging structure, at least all the beneficial effects brought by the technical solutions of the above embodiments are achieved, and therefore repeated description is omitted here.

[0075] The light machine 60 is packaged on the micro-LED module packaging structure and located at the light emitting side of the LED chip 30. Figure 7 As shown in the figure, the protective shell 50 covers the driving chip 20 and the outer periphery of the wire bonding area 11. The protective shell 50 is provided with a relief opening 54 above the LED chip 30. The light machine 60 is packaged on the protective shell 50 and located above the relief opening 54, so that the light emitting side of the LED chip 30 corresponds to the light machine 60. Since the protective shell 50 has high flatness and shape consistency, the light matching degree of the light machine 60 and the LED chip 30 can be improved, and the display effect is improved.

[0076] A sealing glue is arranged between the light machine 60 and the protective shell 50. The sealing glue is arranged around the relief opening 54. The light machine 60 and the protective shell 50 are fixedly connected through the sealing glue and block the relief opening 54. Since the protective shell 50 and the substrate 10 are also sealed and connected through a glue layer, a closed space is formed inside the protective shell 50, which prevents external dust and water vapor from entering the inside of the protective shell 50, thereby protecting the driving chip 20 and the LED chip 30.

[0077] The display device can be a virtual reality (VR) device, an augmented reality (AR) device, smart glasses, etc.

[0078] The above description is only an exemplary embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or any other equivalent transformation within the technical concept of the present application, as described in the specification and drawings, is included in the patent protection scope of the present application.

Claims

1. A micro LED module packaging structure, characterized in that: The micro LED module packaging structure includes: A substrate, comprising a patch area and a wire bonding area; A driver chip is mounted on the patch area and electrically connected to the bonding area via leads; an LED chip, the LED chip being bonded to the driver chip and emitting light under the drive of the driver chip; and A protective shell is mounted on the substrate and encloses the substrate and the driver chip to form a protective cavity for accommodating the leads.

2. The micro LED module packaging structure according to claim 1, wherein: The protective shell is provided on the driving chip and the wire bonding area and is bonded to the substrate via an adhesive layer. The protective shell is provided with an escape opening, the size of which is greater than or equal to the size of the LED chip so as to expose the LED chip.

3. The micro LED module packaging structure according to claim 2, wherein: The protective shell includes a cover plate, a frame and a support block provided on the surface of the cover plate. The frame is provided around the periphery of the cover plate facing the LED chip and is connected to the substrate. The support block abuts against the surface of the driver chip.

4. The micro LED module packaging structure according to claim 3, wherein: The support block is arranged near the side of the driver chip connected to the lead and extends parallel to the side of the driver chip near the lead. The support block, at least part of the frame, at least part of the cover, the substrate and the driver chip form the protection cavity.

5. The micro LED module packaging structure according to claim 4, wherein: The cover plate is in contact with at least a portion of the surface of the driver chip away from the leads.

6. The micro LED module packaging structure according to claim 3, wherein: The support block extends along the periphery of the avoidance opening to form an annular support structure.

7. The micro LED module packaging structure according to any one of claims 1 to 6, wherein: The protective shell is an integrally formed structure made by injection molding or 3D printing.

8. The micro LED module packaging structure according to any one of claims 1 to 6, wherein: A glue containing groove is formed on the surface of the protective shell facing the substrate. The glue containing groove extends along the periphery of the protective shell and surrounds the outer periphery of the driving chip and the wire bonding area.

9. The micro LED module packaging structure according to any one of claims 1 to 6, wherein: The height difference between the highest point of the lead and the top wall of the protection cavity is H, 25um≤H≤75um; And / or, the shortest distance between the LED chip and the edge of the substrate is D, 200um≤D≤400um.

10. The micro LED module packaging structure according to any one of claims 1 to 6, wherein: The micro LED module packaging structure also includes a heat sink. The substrate is a flexible circuit board. The heat sink is arranged on the side of the substrate away from the protective shell. The projection of the protective shell on the surface of the substrate is located within the projection area of ​​the heat sink on the surface of the substrate.

11. The micro LED module packaging structure according to any one of claims 1 to 6, wherein: The surface of the protective shell facing away from the substrate is parallel to the light-emitting surface of the LED chip.

12. A method for preparing a micro LED module packaging structure, characterized in that: The preparation method comprises the steps of: Bonding the driver chip and the LED chip to form a light-emitting device; Dispensing glue on the surface of the patch area of ​​the substrate, and attaching the light-emitting device to the patch area; electrically connecting the driver chip to the bonding area of ​​the substrate through the lead wire; Glue is dispensed on the surface of the substrate, and the protective shell is attached to the surface of the substrate and covers the leads and the wire bonding area.

13. A display device, characterized in that: The display device comprises an optical engine and a micro LED module packaging structure according to any one of claims 1 to 11; The optical engine is packaged on the micro LED module packaging structure and is located on the light-emitting side of the LED chip.

14. The display device according to claim 13, wherein The protective shell is provided with an escape opening, the LED chip is exposed in the escape opening, the optical engine is arranged on the protective shell and blocks the escape opening, and the optical engine and the protective shell are sealed and connected by a sealant.

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