A COB packaging structure

Abstract

The present invention provides a COB packaging structure. The positive and negative pads are arranged on the circuit substrate. The electrode placement directions of the vertical chips at the positive and negative pads are opposite. The upper electrodes of the vertical chips are opposite to the electrodes on the adjacent flip chips close to the vertical chips. The upper electrodes of the vertical chips are connected to the flip chips through bonding wires. The lower electrodes of the vertical chips are connected to the positive pad or the negative pad through electrical connectors. The flip chips are fixed on the circuit substrate through insulating parts. The flip chips are connected to each other through bonding wires. The light conversion layer is coated on the chips and wraps the bonding wires. Both the chips and the light conversion layer are located in the area surrounded by the barrier walls. In the present invention, the bonding wires are omitted between the chip electrodes and the pads on the circuit substrate, avoiding the reliability problem of the bonding wire breakage at the edge. The advantages of the traditional COB flip chip packaging are maintained, and the packaging method is compatible with the existing production process, and large-scale production can be achieved without additional equipment investment.

Description

Technical Field

[0001] The present invention relates to the technical field of light-emitting diode (LED) packaging, and particularly to a COB packaging structure. Background Art

[0002] Currently, the packaging forms of light-emitting diodes (LEDs) are mainly divided into SMD, COB, CSP, etc. COB has the advantages of soft light, simple circuit design, high cost-effectiveness, saving system space, high thermal conductivity, high light density output, and high light quality. Its obvious advantages in the commercial lighting field make it the mainstream solution for current directional lighting.

[0003] COB packaging, simply speaking, is to directly fix multiple LED chips on a circuit substrate. For a face-up chip, bonding wires are used to electrically connect the chip to the chip and the positive and negative pads on the circuit board. As Figure 1 shown, it is the most common COB packaging structure currently. For a flip-chip or vertical chip, complex circuit wiring design needs to be carried out on the circuit substrate, and the chip cost is relatively high. Therefore, the mainstream chip used in current COB packaging is a face-up chip.

[0004] As Figure 1 shown in the face-up chip COB packaging structure, the bonding wires between the chips are relatively short, but the bonding wires from the chip to the pads on the circuit substrate are relatively long, and the bonding wires are generally pressed by a barrier wall. In this case, the bonding wires are easily broken under external extrusion or pulled by silicone during use. The current methods of packaging factories are, one is to use bonding wires with a larger wire diameter, but the cost increases and the risk still exists; the second is to optimize the wire bonding arc parameters, but the fundamental problem of the long wire arc cannot be solved; the third is to use flip-chips without bonding wires. No matter which method is used, the reliability problem of bonding wire breakage is not solved from the front. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a COB packaging structure, in which the bonding wires are omitted between the vertical chip electrodes and the pads on the circuit substrate, thereby avoiding the reliability problem of bonding wire breakage at the edge.

[0006] The present invention provides a COB packaging structure, including a vertical chip, a flip chip, a circuit board, a positive electrode pad, a negative electrode pad, an insulator, an electrical connector, a barrier wall, and a light conversion layer. The positive electrode pad and the negative electrode pad are disposed on the circuit board. The vertical chip is disposed at the positive electrode pad and the negative electrode pad. The electrode placement directions of the vertical chips disposed at the positive electrode pad and the vertical chips disposed at the negative electrode pad are opposite. The upper-end electrode of the vertical chip is opposite to the electrode on the adjacent flip chip close to the vertical chip. The upper-end electrode of the vertical chip is connected to the flip chip through a bonding wire. The lower-end electrode of the vertical chip is connected to the positive electrode pad or the negative electrode pad through the electrical connector. The flip chip is fixed on the circuit board through the insulator. The flip chips are connected to each other through bonding wires. The light conversion layer is coated on the vertical chip and the flip chip and wraps the bonding wires. The vertical chip, the flip chip, and the light conversion layer are all located within the area surrounded by the barrier wall.

[0007] Further, the circuit board is a planar substrate.

[0008] Further, the planar substrate is Al2O3, AlN, Cu, Al, or a composite material.

[0009] Further, the surfaces of the positive electrode pad and the negative electrode pad are plated with Au, Ag, or sprayed with Sn conductive materials.

[0010] Further, the light conversion layer is a mixture of light conversion materials mixed in silicone in proportion.

[0011] Further, the electrical connector is a conductive adhesive.

[0012] Further, the insulator is an insulating adhesive.

[0013] Further, the positive and negative electrodes of the flip chip are distributed on both sides of the upper part of the chip. The positive and negative electrodes of the flip chip are connected to adjacent chips through bonding wires.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] The present invention disposes vertical chips on one side of the pads of the circuit board. The vertical chips are fixed on the pads of the circuit board using a conductive adhesive and are electrically connected to the circuit board directly through the bottom electrodes. The bonding wires are omitted between the chip electrodes and the pads of the circuit board, thus avoiding the reliability problem of bonding wire breakage at the edge. This packaging structure retains the advantages of the traditional COB flip chip packaging, and its packaging method is compatible with the existing production process, and large-scale production can be achieved without additional equipment investment.

[0016] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and be implemented in accordance with the content of the specification, the following describes in detail with reference to the preferred embodiments of the present invention and the accompanying drawings. The specific implementation manners of the present invention are given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and form a part of this application. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 is the flip chip COB packaging structure in the background technology of the present invention;

[0019] Figure 2 is a schematic diagram of a COB packaging structure of the present invention;

[0020] Figure 3 is the vertical chip schematic of the present invention Figure 1 ;

[0021] Figure 4 is the vertical chip schematic of the present invention Figure 2 ;

[0022] Figure 5 is the flip chip schematic of the present invention.

[0023] In the figure: 1, circuit board; 2, positive electrode pad; 3, negative electrode pad; 4, insulating glue; 5, conductive glue; 6, vertical chip; 7, light conversion layer; 8, flip chip; 9, bonding wire; 10, barrier wall. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Next, with reference to the accompanying drawings and specific implementation manners, the present invention will be further described. It should be noted that, on the premise of no conflict, any combination of the following described embodiments or technical features can form a new embodiment.

[0025] A COB packaging structure, as Figure 2As shown in the figure, it includes a vertical chip 6, a flip chip 8, a circuit board 1, a positive electrode pad 2, a negative electrode pad 3, an insulating member, an electrical connection member, a barrier wall 10, and a light conversion layer 7. The positive electrode pad 2 and the negative electrode pad 3 are arranged on the circuit board 1. The vertical chip 6 is arranged at the positive electrode pad 2 and the negative electrode pad 3. The electrode placement directions of the vertical chip 6 arranged at the positive electrode pad 2 and the vertical chip 6 arranged at the negative electrode pad 3 are opposite. The upper electrode of the vertical chip 6 is opposite to the electrode on the adjacent flip chip 8 close to the vertical chip 6. The upper electrode of the vertical chip 6 is connected to the flip chip 8 through a bonding wire 9. The lower electrode of the vertical chip 6 is connected to the positive electrode pad 2 or the negative electrode pad 3 through an electrical connection member. The flip chip 8 is fixed on the circuit board 1 through an insulating member. The flip chips 8 are connected to each other through bonding wires 9. The light conversion layer 7 is coated on the vertical chip 6 and the flip chip 8 and wraps the bonding wires 9. Preferably, the light conversion layer 7 is a mixture of a light conversion material mixed in silicone in a certain proportion. The vertical chip 6, the flip chip 8, and the light conversion layer 7 are all located within the area surrounded by the barrier wall 10.

[0026] In one embodiment, the circuit board 1 is a planar substrate, and the planar substrate is Al2O3, AlN, Cu, Al, or a composite material, etc. The positive electrode pad 2 and the negative electrode pad 3 are used to connect to an external power supply, and the surfaces of the positive electrode pad 2 and the negative electrode pad 3 are plated with conductive materials such as Au, Ag, or sprayed with Sn, etc.

[0027] In one embodiment, the electrical connection member is a conductive adhesive 5, and the vertical chip 6 arranged at the positive electrode pad 2 is fixed on the positive electrode pad 2 through the conductive adhesive 5. The electrode structure of one of the vertical chips 6 is as Figure 3 shown. The electrodes 6a and 6b are distributed at the upper and lower ends of the vertical chip 6. The two electrodes are the positive and negative electrodes respectively in the vertical direction of the chip. Among them, the upper electrode is connected to the flip chip 8 through a bonding wire 9, and the lower electrode is connected to the positive electrode pad 2 through the conductive adhesive 5. The vertical chip 6 arranged at the negative electrode pad 3 is fixed on the negative electrode pad 3 through the conductive adhesive 5. The electrode structure of the other vertical chip 6 is as Figure 4 shown. The electrodes 6c and 6d are distributed at the upper and lower ends of the vertical chip 6. The upper electrode is connected to the flip chip 8 through a bonding wire 9, and the lower electrode is connected to the negative electrode pad 3 through the conductive adhesive 5. It should be understood that the vertical chip 6 arranged at the positive electrode pad 2 and the vertical chip 6 arranged at the negative electrode pad 3 are located at the head and tail of this series circuit, and the positive and negative electrode directions of the two are opposite. If the electrodes of the vertical chip 6 arranged at the positive electrode pad 2 are positive at the top and negative at the bottom, then the vertical chip 6 arranged at the negative electrode pad 3 is negative at the top and positive at the bottom.

[0028] In one embodiment, the insulating member is an insulating adhesive 4, and the flip chip 8 is fixed on the circuit board 1 through the insulating adhesive 4. As Figure 5As shown, the positive electrode 8a and the negative electrode 8b of the flip-chip 8 are distributed on both sides of the upper part of the chip. The two electrodes are in the horizontal direction of the chip, being the positive electrode and the negative electrode respectively. The positive electrode and the negative electrode of the flip-chip 8 are connected to adjacent chips through bonding wires 9. It should be understood that the electrode directions of the flip-chip 8 match those of the vertical chip 6. If the vertical chip 6 has a positive electrode on the upper side and a negative electrode on the lower side, the electrode of the flip-chip 8 close to the vertical chip 6 is the negative electrode, and vice versa.

[0029] In the present invention, a vertical chip is arranged on one side of the pad of the circuit board. The vertical chip is fixed on the pad of the circuit board by conductive adhesive and is electrically connected to the circuit board directly through the bottom electrode. The bonding wires are omitted between the chip electrode and the pad of the circuit board, thus avoiding the reliability problem of the bonding wire breakage at the edge. This packaging structure retains the advantages of the traditional COB flip-chip packaging, and its packaging method is compatible with the existing production process, and large-scale production can be achieved without additional equipment investment.

[0030] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any ordinary technician in the industry can smoothly implement the present invention as shown in the accompanying drawings of the specification and the above. However, any equivalent changes such as slight modifications, decorations, and evolutions made by those skilled in the art within the scope of the technical solution of the present invention by using the technical content disclosed above are equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A COB packaging structure, characterized in that: It includes a vertical chip, a flip-chip, a circuit board, a positive electrode pad, a negative electrode pad, an insulator, an electrical connector, a barrier wall, and a light conversion layer. The positive electrode pad and the negative electrode pad are arranged on the circuit board. The vertical chip is arranged at the positive electrode pad and the negative electrode pad. The electrode placement directions of the vertical chips arranged at the positive electrode pad and the vertical chips arranged at the negative electrode pad are opposite. The upper electrode of the vertical chip is opposite to the electrode on the adjacent flip-chip close to the vertical chip. The upper electrode of the vertical chip is connected to the flip-chip through a bonding wire. The lower electrode of the vertical chip is connected to the positive electrode pad or the negative electrode pad through the electrical connector. The flip-chip is fixed on the circuit board through the insulator. The flip-chips are connected to each other through bonding wires. The light conversion layer is coated on the vertical chip and the flip-chip and wraps the bonding wire. The vertical chip, the flip-chip, and the light conversion layer are all located within the area surrounded by the barrier wall; the light conversion layer is a mixture of light conversion materials mixed in silicone in proportion.

2. A COB packaging structure according to claim 1, characterized in that: The circuit board is a planar substrate.

3. A COB packaging structure according to claim 2, characterized in that: The planar substrate is Al2O3, AlN, Cu, or Al.

4. A COB packaging structure according to claim 1, characterized in that: The surfaces of the positive electrode pad and the negative electrode pad are plated with conductive materials such as Au, Ag, or sprayed with Sn.

5. A COB packaging structure according to claim 1, characterized in that: The electrical connector is a conductive adhesive.

6. A COB packaging structure according to claim 1, characterized in that: The insulator is an insulating adhesive.

7. A COB packaging structure according to claim 1, characterized in that: The positive and negative electrodes of the flip-chip are distributed on both sides of the upper part of the chip. The positive and negative electrodes of the flip-chip are connected to adjacent chips through bonding wires.

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