Light emitting diode package structure

Abstract

of an area of the insulating layer. The light-emitting diodes are embedded in the insulating layer, and the light-emitting diodes are arranged around the process working region. The circuit layer is embedded in the insulating layer and electrically connected to the light-emitting diodes. The bonding pads are disposed under the insulating layer and electrically connected to the circuit layer. The light conversion layer is disposed on the insulating layer. The process working region overlaps with a geometric center of the light-emitting diode package structure in a top view.

Description

Technical Field

[0001] This disclosure relates to a light-emitting diode (LED) packaging structure, and more particularly to a thin LED packaging structure. Prior Technology

[0002] With the rapid development of electronic devices, the components within them are gradually being miniaturized. Taking light-emitting diode (LED) packaging structures as an example, the significant reduction in LED size has greatly increased the difficulty of the manufacturing process, leading to problems such as decreased yield. Therefore, although existing LED packaging structures have gradually met their intended uses, they are not perfect in every aspect. Consequently, there are still some issues regarding LED packaging structures that need to be overcome. Summary of the Invention

[0003] This disclosure provides a light-emitting diode (LED) packaging structure that can increase process yield and improve luminous efficiency. The LED packaging structure includes an insulating layer, a plurality of LEDs, a circuit layer, a plurality of bonding pads, and a light conversion layer. The insulating layer has a process working area, and the area of ​​the process working area occupies 2% to 50% of the total area of ​​the insulating layer. The LEDs are embedded in the insulating layer and arranged around the process working area. The circuit layer is embedded in the insulating layer and electrically connects to the LEDs. The bonding pads are disposed under the insulating layer and electrically connect to the circuit layer. The light conversion layer is disposed on the insulating layer. Viewed from top, the process working area overlaps with the geometric center of the LED packaging structure.

[0004] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are intended to provide further explanation of the claimed content of this disclosure. Simple Explanation of the Diagram

[0005] This disclosure can be more fully understood by reading the following detailed description of the embodiments and referring to the accompanying drawings. Figure 1 is a cross-sectional schematic diagram of a light-emitting diode packaging structure according to various embodiments of the present disclosure. Figure 2 is a top view schematic diagram of various embodiments of the light-emitting diode packaging structure according to the present disclosure. Figure 3 is a bottom view schematic diagram of the light-emitting diode packaging structure according to various embodiments of the present disclosure. Figure 4 is a cross-sectional schematic diagram of the light-emitting diode packaging structure according to various embodiments of the present disclosure. Implementation

[0006] Embodiments of the present disclosure will now be described in detail, examples of which are illustrated in the accompanying drawings. Where possible, the same reference numerals are used in the drawings and description to refer to the same or similar parts.

[0007] The following plurality of embodiments are described and disclosed in detail with reference to the accompanying drawings. For clarity, many practical details will be set forth in the following description. However, it should be understood that these practical details are not intended to limit the scope of this disclosure. That is, these practical details are not essential in some embodiments of this disclosure. Furthermore, for the sake of simplicity, some known structures and elements will be shown schematically in the drawings.

[0008] In this document, the range expressed as "from one value to another" is a concise way of representing a range to avoid listing all the values ​​in that range in the specification. Therefore, the description of a specific range of values ​​covers any value within that range as well as the smaller range of values ​​defined by that value, just as if the arbitrary value and the smaller range of values ​​were explicitly stated in the specification.

[0009] This disclosure provides a light-emitting diode (LED) packaging structure that not only increases process yield but also improves luminous efficiency. Figure 1 is a cross-sectional view of the LED packaging structure according to various embodiments of this disclosure. Figure 2 is a top view of the LED packaging structure according to various embodiments of this disclosure. Figure 3 is a bottom view of the LED packaging structure according to various embodiments of this disclosure. More specifically, Figure 1 is a cross-sectional view along section line 1-1 in Figure 2, and the top view in Figure 2 omits the light conversion layer to more clearly show the corresponding positions of other components.

[0010] Please refer to Figures 1, 2, and 3 simultaneously. The light-emitting diode (LED) package structure 10 includes an insulating layer 110, a plurality of LEDs 120, a circuit layer 130, a plurality of bonding pads 140, and a light conversion layer 150. Specifically, the plurality of LEDs 120 are located in the insulating layer 110, the light conversion layer 150 covers the insulating layer 110 and the plurality of LEDs 120, the plurality of bonding pads 140 are located on one side of the insulating layer 110 opposite to the light conversion layer 150, such that the insulating layer 110 is located between the plurality of bonding pads 140 and the light conversion layer 150, and the circuit layer 130 is located in the insulating layer 110 and is electrically connected to the plurality of LEDs 120 and the plurality of bonding pads 140.

[0011] In some embodiments, the insulating layer 110 has a process working area 116, around which a plurality of light-emitting diodes 120 are symmetrically disposed. It should be noted that the "process working area 116" as used herein is intended for use in the manufacturing process of the light-emitting diode packaging structure. In one embodiment, it is the working area during the operation of a fixture or jig in the process. For example, it is the area where the fixture or jig contacts the product and / or semi-finished product during the process, thus preventing damage to the light-emitting diodes 120 during the operation of the fixture or jig. In this embodiment, no light-emitting diodes 120 may be disposed in the "process working area 116". That is, the vertical projection range of any one of the plurality of light-emitting diodes 120 does not overlap with the vertical projection range of the process working area 116. In some embodiments, the area of ​​the process working area 116 accounts for 2% to 50% of the total area of ​​the insulating layer 110, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. In some embodiments, when the area of ​​the process working area 116 is greater than a certain value relative to the total area of ​​the insulating layer 110, such as 50%, it is difficult to install the light-emitting diode 120 and the circuit layer 130. Conversely, in some embodiments, when the area of ​​the process working area 116 is less than a certain value relative to the total area of ​​the insulating layer 110, such as 2%, it is easy to damage the light-emitting diode 120 and / or the circuit layer 130 during the process when the fixture or jig is operated. It should be noted that, when viewed from above, the process working area 116 overlaps with the geometric center of the light-emitting diode package structure 10, as shown in Figure 2.

[0012] In some embodiments, the insulating layer 110 comprises an insulating material, such as silicon oxide (SiO2), aluminum oxide (Al2O3), titanium dioxide (TiO2), hafnium dioxide (HfO2), tantalum oxide (Ta2O5), silicon nitride (Si3N4), compounds of the foregoing materials, or stacked combinations thereof, and this disclosure is not limited to the above list. In some embodiments, the insulating layer 110 comprises a stacked first insulating layer 112 and a second insulating layer 114, the first insulating layer 112 being located between the second insulating layer 114 and the light conversion layer 150. In some embodiments, the first insulating layer 112 or the second insulating layer 114 may reflect light emitted by the light-emitting diode 120, and the reflectivity of the first insulating layer 112 or the second insulating layer 114 is at least greater than 80%. For example, the first insulating layer 112 or the second insulating layer 114 may be a distributed Bragg reflector (DBR). A dispersed Bragg reflector may comprise a periodic structure consisting of alternating layers of two materials with different refractive indices. For example, a dispersed Bragg reflector may be constructed from alternating stacks of SiO2 and TiO2 or from alternating stacks of SiO2 / Al2O3 / TiO2. This design can increase the luminous efficiency of the light-emitting diode encapsulation structure 10. In some embodiments, the reflectivity of the first insulating layer 112 or the second insulating layer 114 to the light emitted by the light-emitting diode 120 is not less than 80%, for example, 80%, 85%, 90%, 95%, or 99%.

[0013] Please refer to Figures 1, 2, and 3. A plurality of light-emitting diodes 120 are embedded in an insulating layer 110, and these light-emitting diodes 120 are separated from each other by the insulating layer 110. In some embodiments, the insulating layer 110 surrounds the plurality of light-emitting diodes 120 and exposes the light-emitting surface 122 of each light-emitting diode 120. In some embodiments, the light-emitting diode 120 is a thin-film LED without a substrate, in which case the light-emitting surface 122 of the light-emitting diode 120 is the surface of the semiconductor layer. In some embodiments, the light-emitting surface 122 of each light-emitting diode 120 is flush with the upper surface 113 of the insulating layer 110. In some embodiments, the plurality of light-emitting diodes 120 are arranged around a process working area 116. For example, as shown in Figure 2, the plurality of light-emitting diodes 120 are spaced apart from each other and symmetrically arranged on any two opposite sides of the process working area 116. The number of light-emitting diodes 120 is preferably even, such as 2, 4, 6, 8, 10 or more, but this disclosure is not limited thereto. In some embodiments, these light-emitting diodes 120 are embedded in the first insulating layer 112.

[0014] In some embodiments, each light-emitting diode 120 has a thickness T1 ranging from 3 micrometers to 20 micrometers. For example, the thickness T1 of each light-emitting diode 120 can be 5 micrometers, 10 micrometers, or 15 micrometers. In some embodiments, when the thickness T1 of the light-emitting diode 120 is greater than a certain value, such as 20 micrometers, the lateral light ratio of the light-emitting diode 120 is increased, while the axial brightness is reduced. Conversely, when the thickness T1 of the light-emitting diode 120 is less than a certain value, such as 3 micrometers, the manufacturing process becomes significantly more difficult. In some embodiments, each light-emitting diode 120 has a plurality of electrodes 124 disposed on the side opposite to the light conversion layer 150. In some embodiments, at least two of the plurality of electrodes 124 have different polarities, such as positive and negative electrodes.

[0015] Please refer to Figures 1, 2, and 3. The circuit layer 130 is embedded in the insulating layer 110 and electrically connected to a plurality of light-emitting diodes 120. In some embodiments, the circuit layer 130 is disposed along the interface between the first insulating layer 112 and the second insulating layer 114 and embedded in the second insulating layer 114, and the circuit layer 130 extends into the first insulating layer 112 to be electrically connected to the electrodes 124 of the plurality of light-emitting diodes 120. In some embodiments, the plurality of light-emitting diodes 120 form a series circuit, a parallel circuit, or an independent circuit through the circuit layer 130.

[0016] In some embodiments, the circuit layer 130 includes a plurality of mutually separated sub-circuits. Each light-emitting diode 120 has electrodes 124 of different polarities that are electrically connected to different sub-circuits. The number of sub-circuits can be determined according to circuit design requirements. For example, when it is desired that a plurality of light-emitting diodes 120 can display brightness and darkness synchronously, the number of sub-circuits will be the same as the number of polarities of the electrodes 124 of the light-emitting diodes 120. For example, in this embodiment, each light-emitting diode 120 has two electrodes 124 of different polarities, and the circuit layer 130 includes two sub-circuits. One sub-circuit is connected to one electrode 124 of each light-emitting diode 120, and the other sub-circuit is connected to the other electrode 124 of each light-emitting diode 120, as shown in Figure 2. When it is desired that a plurality of light-emitting diodes 120 can independently control the brightness and darkness of their displays, the number of sub-circuits will be greater than the number of light-emitting diodes 120.

[0017] In some embodiments, the circuit layer 130 comprises a conductive material, such as copper (Cu), silver (Ag), aluminum (Al), nickel (Ni), platinum (Pt), palladium (Pd), gold (Au), alloys thereof, or combinations thereof. In some embodiments, the circuit layer 130 is disposed at the periphery of the process working area 116. In some embodiments, the circuit layer 130 surrounds the process working area 116. In some embodiments, the vertical projection range of the circuit layer 130 does not overlap with the vertical projection range of the process working area 116.

[0018] A plurality of bonding pads 140 are disposed under the insulating layer 110 and electrically connected to the circuit layer 130, as shown in Figures 1 and 2. Specifically, the plurality of bonding pads 140 are located on the side of the insulating layer 110 opposite to the light conversion layer 150 and extend into the insulating layer 110 to be electrically connected to the circuit layer 130. That is, a plurality of light-emitting diodes 120 are electrically connected to the plurality of bonding pads 140 via the circuit layer 130. In some embodiments, the number of bonding pads 140 is the same as the number of sub-circuits of the circuit layer 130. For example, in this embodiment, there are two bonding pads 140, which are electrically connected to two sub-circuits of the circuit layer 130, as shown in Figure 2.

[0019] In some embodiments, the material of the bonding pad 140 may include a metal. For example, the metal material may include aluminum (Al), copper (Cu), indium (In), platinum (Pt), tin (Sn), gold (Au), zinc (Zn), titanium (Ti), silver (Ag), nickel (Ni), alloys thereof, or combinations thereof, but this disclosure is not limited thereto.

[0020] In some embodiments, in cross-section, any two adjacent electrodes 124 of any light-emitting diode 120 have a first distance D1 in the horizontal direction, and any two adjacent bonding pads 140 have a second distance D2 in the horizontal direction, wherein the second distance D2 is greater than the first distance D1. In some embodiments, in top view, the area of ​​the plurality of bonding pads 140 covers the area of ​​all light-emitting diodes 120. In other words, the vertical projection area of ​​any light-emitting diode 120 is located within the vertical projection area of ​​one of the bonding pads 140.

[0021] In some embodiments, the bonding pads 140 are disposed around the periphery of the process working area 116. In some embodiments, a plurality of bonding pads 140 are symmetrically arranged with the process working area 116 as the center. In some embodiments, the vertical projection range of the bonding pads 140 does not overlap with the vertical projection range of the process working area 116.

[0022] As shown in Figure 1, the light conversion layer 150 is disposed on the insulating layer 110. Specifically, the light conversion layer 150 is disposed on the upper surface 113 of the insulating layer 110 and the light-emitting surface 122 of the light-emitting diode 120. In some embodiments, the light conversion layer 150 continuously covers all the light-emitting diodes 120. In other words, the light conversion layer 150 continuously spans all the light-emitting diodes 120 so that all the light-emitting diodes 120 share a single light conversion layer 150.

[0023] In some embodiments, the light conversion layer 150 comprises a substrate (not shown) and a luminescent material (not shown) distributed within the substrate. The substrate is permeable to light emitted by the light-emitting diode 120, and the substrate material is, for example, resin, glass, ceramic, other suitable materials, or combinations thereof. The transmittance of light emitted by the light-emitting diode 120 through the substrate is not less than 80%, for example, 80%, 85%, 90%, 95%, or 100%. The luminescent material has the ability to absorb light emitted by the light-emitting diode 120, convert its wavelength, and then emit it again; the luminescent material is, for example, phosphor or quantum dot (QD).

[0024] In some embodiments, the light conversion layer 150 has a second thickness T2, which is greater than the first thickness T1 of each light-emitting diode 120, and the second thickness T2 is less than 200 micrometers. In some embodiments, when the second thickness T2 is less than a certain value, such as the first thickness T1, the support of the light-emitting diode packaging structure 10 will be insufficient. Conversely, in some embodiments, when the second thickness T2 is greater than a certain value, such as 200 micrometers, the transmittance of the light emitted by the light-emitting diode 120 will be affected. In some embodiments, the light conversion layer 150 can be directly bonded to the upper surface 113 of the insulating layer 110 and the light-emitting surface 122 of each light-emitting diode 120.

[0025] Figure 4 is a cross-sectional schematic diagram of a light-emitting diode (LED) packaging structure according to various embodiments of the present disclosure. As shown in Figure 4, the LED packaging structure 20 may further include an adhesive layer 160 disposed between the light conversion layer 150 and the light-emitting surfaces 122 of each LED 120. Specifically, the adhesive layer 160 simultaneously covers the upper surface 113 of the insulating layer 110 and the light-emitting surfaces 122 of each LED 120, and the adhesive layer 160 is covered by the light conversion layer 150, as shown in Figure 4. The adhesive layer 160 can further improve the bonding strength between the light conversion layer 150 and the upper surface 113 and the light-emitting surfaces 122. In some embodiments, the adhesive layer 160 includes a light-transmitting material that can be penetrated by light emitted from the LED 120, such as polymide (PI), silicone, epoxy resin, other suitable adhesive materials, or combinations thereof. The light emitted by the light-emitting diode 120 has a transmittance of not less than 80% through the adhesive layer 160, for example, 80%, 85%, 90%, 95% or 100%.

[0026] In summary, the LED packaging structure disclosed herein utilizes a thin-film LED to form a thin-film packaging structure, which is beneficial for the application of thin devices. Furthermore, by employing redistribution layer (RDL) technology, the relatively small and narrow-gap electrical contacts (electrodes) in the LED are extended through the circuit layer to the larger and wider-gap bonding pads, helping to reduce the bonding process difficulty of small-size packaging structures. Simultaneously, arranging the LED and circuit layer around the process working area located in the center of the packaging structure further prevents damage to the LED and / or circuit layer in subsequent processes, thereby increasing yield. For example, when using a jig to move the packaging structure onto the carrier for bonding, the jig can apply force to the process working area where the LED and circuit layer are not located. Because the force application point is close to the geometric center of the packaging structure, the packaging structure can be evenly stressed and maintain balance during movement. In addition, placing a reflective insulating layer (such as a Bragg mirror) at the bottom of the encapsulation structure (on the side adjacent to the bonding pad) can improve luminous efficiency.

[0027] Although this disclosure has been described in considerable detail with reference to certain embodiments, other embodiments may also be possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments included herein.

[0028] It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of this disclosure without departing from its scope or spirit. In view of the foregoing, this disclosure is intended to cover modifications and variations of this disclosure that fall within the scope of the appended patent applications.

[0029] 10,20: Light-emitting diode packaging structure 110: Insulation layer 112: First insulating layer 113: Upper surface 114: Second Insulation Layer 116: Process Work Area 120: Light Emitting Diode 122: Exposed surface 124: Electrode 130: Line Layer 140: Joint pad 150: Light conversion layer 160: Adhesive layer 1-1: Section D1: First Distance D2: Second distance T1: Thickness T2: Thickness

[0030] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A light-emitting diode (LED) packaging structure, comprising: An insulating layer having a process working area, wherein the area of ​​the process working area occupies 2% to 50% of the total area of ​​the insulating layer; a plurality of light-emitting diodes (LEDs) embedded in the insulating layer and arranged around the process working area; a circuit layer embedded in the insulating layer and electrically connected to the LEDs; a plurality of bonding pads disposed under the insulating layer and electrically connected to the circuit layer; and a light conversion layer disposed on the insulating layer, wherein, in a top view, the process working area overlaps with a geometric center of the LED package structure.

2. The light-emitting diode packaging structure as described in claim 1, wherein a light-emitting surface of each light-emitting diode is flush with an upper surface of the insulating layer.

3. The light-emitting diode packaging structure as described in claim 1 further includes an adhesive layer disposed between the light conversion layer and the light-emitting diodes.

4. The light-emitting diode packaging structure as claimed in claim 1, wherein each light-emitting diode has a plurality of electrodes disposed on a side opposite to the light conversion layer, wherein any two adjacent electrodes have a first distance between them, and any two adjacent bonding pads have a second distance between them, and the second distance is greater than the first distance.

5. The light-emitting diode packaging structure as described in claim 1, wherein each light-emitting diode has a thickness of 3 micrometers to 20 micrometers.

6. The light-emitting diode packaging structure as described in claim 1, wherein the insulating layer includes a first insulating layer and a second insulating layer located below the first insulating layer, the light-emitting diodes are embedded in the first insulating layer, and the circuit layer is embedded in the second insulating layer.

7. The light-emitting diode packaging structure as described in claim 6, wherein the first insulating layer or the second insulating layer reflects the light emitted by the light-emitting diodes, and the reflectivity of the first insulating layer or the second insulating layer is at least greater than 80%.

8. The light-emitting diode package structure as described in claim 1, wherein the light-emitting diodes are spaced apart and symmetrically arranged on any two opposite sides of the process working area.

9. The light-emitting diode packaging structure as described in claim 1, wherein each light-emitting diode has a first thickness, the light conversion layer has a second thickness, and the second thickness is greater than the first thickness and less than 200 micrometers.

10. The light-emitting diode packaging structure as described in claim 1, wherein the light conversion layer continuously covers the light-emitting diodes.

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