CN221176258U - COB display screen and display device - Google Patents

Abstract

The application belongs to the technical field of display devices, and provides a COB display screen and a display device. The LED chip comprises a chip body and two pins arranged on the bottom surface of the chip body, wherein the two pins are respectively and electrically connected with the two bonding pads, and the melting point of each pin is lower than that of each bonding pad. According to the COB display screen provided by the application, during preparation, after two pins of the LED chips are respectively placed on the two bonding pads, reflow soldering operation can be directly performed, and as the volumes of the two pins at normal temperature can be accurately controlled, the solder paste quantity on the two bonding pads is accurately controlled, the conditions that one side of a single LED chip is high and the other side of the single LED chip is low can be avoided as much as possible, the conditions that the heights of different LED chips are different can be avoided as much as possible, and the COB display screen has better light color consistency.

Description

COB display screen and display device

Technical Field

The application relates to the technical field of display devices, in particular to a COB display screen and a display device.

Background

In the prior art, a COB display screen generally includes a substrate and a plurality of LED chips, and the plurality of LED chips are generally soldered on bonding pads of the substrate respectively through a reflow soldering manner, that is, firstly, a steel mesh is adopted to print solder paste on the bonding pads of the substrate, then, a manipulator is adopted to place the plurality of LED chips on the plurality of bonding pads printed with solder paste respectively, and then high-temperature reflow soldering is performed, so that the plurality of LED chips can be fixed on the plurality of bonding pads respectively after melting, but in the process, when the amounts of solder paste printed on different bonding pads are different, the conditions of high side and low side of a single LED chip are easy to appear, the conditions of different heights of different LED chips are easy to appear, and the conditions are easy to cause a phenomenon of 'screen pattern' of inconsistent light color of the COB display screen, thereby seriously affecting the display effect.

Disclosure of utility model

The embodiment of the application aims to provide a COB display screen and a display device, which are used for solving the technical problems that in the prior art, a single LED chip of the COB display screen is easy to have the conditions of high side and low side, and different LED chips are easy to have the conditions of different heights, so that the light color consistency of the COB display screen is poor.

In order to achieve the above purpose, the application adopts the following technical scheme: provided is a COB display screen including:

A substrate;

A plurality of bonding pads which are arranged on the top surface of the substrate at intervals;

the LED chips comprise a chip body and two pins arranged on the bottom surface of the chip body, the two pins are respectively and electrically connected with the two bonding pads, and the melting point of each pin is lower than that of each bonding pad.

In one embodiment, the pins are tin pins or tin alloy pins.

In one embodiment, the top surface of each bonding pad is provided with a groove; the two pins are respectively inserted and matched with the two grooves, and the shape and the size of each pin are the same as those of the corresponding groove.

In one embodiment, the shape of the groove is prismatic, pyramid, truncated cone, cylinder or hemispherical.

In one embodiment, a first limiting protrusion is further protruding on the substrate, the first limiting protrusion is located between two bonding pads connected with the same LED chip, and a top surface of the first limiting protrusion is flush with a top surface of the bonding pad.

In one embodiment, a second limiting protrusion is further protruding on the substrate, and the second limiting protrusion is located between two groups of bonding pads connected with different LED chips.

In one embodiment, the base plate and the first limit protrusion are integrally formed.

In one embodiment, the substrate and the second limiting protrusion are integrally formed.

In one embodiment, the COB display screen further includes a solder resist ink layer, where the solder resist ink layer is disposed on the substrate and surrounds the outer sides of the pad, the first limiting protrusion, and the second limiting protrusion; the top surface of the solder resist ink layer is flush with the top surface of the bonding pad.

In one embodiment, the substrate comprises a substrate body and a conductive layer arranged on the substrate body, and the substrate body is a resin plate or a glass plate.

In order to achieve the above purpose, the application also provides a display device, which comprises the COB display screen.

The COB display screen and the display device provided by the application have the beneficial effects that: compared with the prior art, the COB display screen provided by the application has the advantages that the structure of the LED chip is improved, the two pins are arranged at the bottom of the LED chip, and the melting points of the two pins are designed to be lower than the melting point of the bonding pad, so that solder paste does not need to be printed on the bonding pad on the substrate, the two pins of the LED chip can be directly subjected to reflow soldering operation after being respectively placed on the two bonding pads, the pins of the LED chip serve as solder paste, namely, after the two pins of the LED chip are melted, the LED chip body is fixed on the two bonding pads, and the volume of the two pins in the normal temperature state can be accurately controlled, so that the solder paste quantity on the two bonding pads is accurately controlled, the situation that one side of a single LED chip is high and the other side of the single LED chip is low can be avoided as much as possible, the situation that the heights of different LED chips are different can be avoided as much as possible, and the COB display screen has better light color consistency.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a COB display screen with an LED chip in an inclined state in the prior art;

fig. 2 is a schematic structural diagram of a COB display screen with an LED chip in an inclined state in the prior art;

Fig. 3 is a schematic structural diagram of a COB display screen with an LED chip in an offset state in the prior art;

Fig. 4 is a schematic structural diagram of a COB display screen with an LED chip in an offset state in the prior art;

Fig. 5 is a schematic structural diagram of a COB display screen according to an embodiment of the present application;

FIG. 6 is a cross-sectional view of the COB display screen and display device shown in FIG. 5 in the A-A direction;

fig. 7 is a B-B cross-sectional view of the COB display screen and display device shown in fig. 5.

Wherein, each reference sign in the figure:

11-a substrate; 12-bonding pads; 13-an LED chip; 14-tin paste.

100-A substrate; 200-bonding pads; 210-groove; 300-LED chips; 310-chip body; 320-pin; 400-a first limit protrusion; 500-a second limit protrusion; 600-solder resist ink layer.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present application and should not be construed as limiting the application.

In the description of the present application, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, the appearances of the phrase "in one embodiment" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Referring to fig. 1 and 2, in the prior art, a COB display screen generally includes a substrate 11 and a plurality of LED chips 13, and the plurality of LED chips 13 are typically soldered on the bonding pads 12 of the substrate 11 by reflow soldering, i.e., firstly, a solder paste 14 is printed on the bonding pads 12 of the substrate 11 by using a steel mesh, then, the plurality of LED chips 13 are respectively placed on the plurality of bonding pads 12 on which the solder paste 14 is printed by using a manipulator, and then high-temperature reflow soldering is performed, so that the plurality of LED chips 13 after melting can be respectively fixed on the plurality of bonding pads 12 by using the melted solder paste 14, but in the above process, referring to fig. 1 and 2, when the amount of solder paste 14 printed on different bonding pads 12 is different, a situation that one side is high and one side is low is easy for different LED chips 13 are also easy to be different in height, and these situations are easy to cause a "screen-patterning" phenomenon that the COB display screen is inconsistent, and seriously affects the display effect.

In order to solve the above-mentioned problems, an embodiment of the present application provides a COB display screen, and referring to fig. 5 to 7, the COB display screen provided by the embodiment of the present application will now be described. The COB display includes a substrate 100, a plurality of pads 200, and a plurality of LED chips 300. Wherein a plurality of pads 200 are disposed on the top surface of the substrate 100 at intervals from each other. The LED chip 300 includes a chip body 310 and two pins 320, the two pins 320 are disposed on the bottom surface of the chip body 310, the two pins 320 are electrically connected to the two pads 200 respectively, and the melting point of each pin 320 is lower than that of the pad 200.

Specifically, the substrate 100 may include a substrate body (not shown, the same applies below) and a conductive layer (not shown, the same applies below) disposed on the substrate body, and it is understood that the conductive layer is provided with the bonding pad 200, that is, the bonding pad 200 is electrically connected to the conductive layer, and the conductive layer may be further provided with a driving circuit capable of driving the LED chip 300. The substrate body may be a glass plate, and the substrate body may also be a gum plate, for example, the base body may be provided with a gum plate made of an organic material such as polyethersulfone, polyetherimide, polyethylene terephthalate, polyphenylene sulfide, polyarylate, polyimide, cellulose triacetate, or cellulose propionate. The material of the substrate body is not limited in this embodiment.

Specifically, referring to fig. 5, the number of the bonding pads 200 may be two, four, six, twelve, etc., and the plurality of bonding pads 200 may be divided into a group every two, and the two bonding pads 200 of the same group are respectively electrically connected to the two pins 320 of the same LED chip 300, so that the number of the bonding pads 200 is not limited only in this embodiment. Also, the pad 200 is made of a material having good conductive properties, such as silver, nickel, gold, or other metal materials with conductive plating, and of course, the pad 200 may be made of other materials, and the material of the pad 200 is not limited only in this embodiment.

Specifically, the plurality of LED chips 300 may be single-color chips, and the plurality of LED chips 300 may be configured to include a red chip, a green chip, and a blue chip at the same time, which is not limited solely in this embodiment.

Specifically, the lead 320 may be made of a conductive material having a melting point between 170 ℃ and 250 ℃, for example, the lead 320 may be a tin lead or a tin alloy lead, although other materials may be used for the lead 320, which is not limited in this embodiment.

Preferably, the lead 320 is made of lead-free solder with a melting point range between 215 ℃ and 250 ℃, and the lead-free solder can be used as a bonding matrix between the LED chip 300 and the substrate 100 to improve the bonding stability between the LED chip 300 and the substrate 100, and has better environmental protection performance.

Compared with the prior art, the COB display screen and the display device provided by the application have the advantages that the structure of the LED chip 300 is improved, the two pins 320 are arranged at the bottom of the LED chip 300, and the melting points of the two pins 320 are designed to be lower than the melting points of the bonding pads 200, so that solder paste does not need to be printed on the bonding pads 200 on the substrate 100, the reflow soldering operation can be directly performed after the two pins 320 of the LED chip 300 are respectively arranged on the two bonding pads 200, the pins 320 of the LED chip 300 serve as solder paste, namely, after the two pins 320 of the LED chip 300 are melted, the LED chip 300 body is fixed on the two bonding pads 200, and because the volumes of the two pins 320 can be accurately controlled at normal temperature, the solder paste quantity on the two bonding pads 200 is accurately controlled, the conditions that one side of a single LED chip 300 is high and the other side is low can be avoided as much as possible, the conditions that different LED chips 300 are different in heights can be avoided as much as possible, and the COB display screen has better light color consistency.

In addition, in the prior art, when the solder paste is printed on the bonding pads 200 by using the steel mesh, the printing positions of the solder paste on the two bonding pads 200 are not easy to be controlled, and when the two pins 320 are arranged on the bottom surface of the same chip body 310, the same chip body 310 is used as a reference, and the arrangement positions of the two pins 320 are easier to be accurately controlled, so that the COB display provided by the embodiment can further reduce the situation of inaccurate die bonding positions of the LED chip 300 caused by inaccurate solder paste printing positions, and further improve the light color consistency of the COB display.

Referring to fig. 3 and 4 in combination, in addition to the above-mentioned amount of solder paste 14 and the printing position of the solder paste 14, the uniformity of the color of the COB display is easily affected, and whether the die bonder robot arm can place the LED chip 13 on the accurate position of the bonding pad 12 when the LED chip 13 is placed on the bonding pad 12 is also a critical factor affecting the uniformity of the color of the COB display. For example, when the die bonder mechanical arm places the LED chip 13, if there is a situation that the device accuracy is low or the alignment correction is abnormal, the placement position of the LED chip 13 is often shifted (refer to fig. 3 and 4), or the LED chip 13 cannot be placed horizontally at the position where the solder paste 14 is printed on the bonding pad 12, that is, the LED chip 13 is tilted when the LED chip 13 is placed, which will affect the light color consistency of the COB display.

In addition, in the prior art, since the solder paste 14 in the molten state has fluidity during the high temperature reflow soldering process, if the surface cleanliness of the substrate 11 is insufficient, the surface of the bonding pad 12 is easily contaminated by the incoming material or the process, the solder paste 14 may deviate to flow to one side of the bonding pad 12, or flow is limited at one position of the bonding pad 12, and finally, the LED chip 13 deviates or inclines due to the distribution difference of the solder paste 14 after the molten flow, which also affects the light color consistency of the COB display.

In order to solve the above-mentioned problem, in another embodiment of the present application, referring back to fig. 5 to 7, the top surface of each pad 200 is provided with a groove 210. The two pins 320 are respectively inserted and matched with the two grooves 210, and the shape and the size of each pin 320 are the same as those of the corresponding groove 210.

Specifically, the shape of the groove 210 may be prismatic, pyramid-shaped, truncated cone-shaped, cylindrical or hemispherical. For example, the shape of the groove 210 may be triangular prism, quadrangular prism, pentagonal prism, hexagonal prism, triangular pyramid, rectangular pyramid, etc., so long as the pin 320 can be inserted into the groove 210 from the open end of the groove 210, and the shapes of the groove 210 and the pin 320 are not limited only in this embodiment.

When the shape of the groove 210 is the same as the shape of the lead 320, and the size of the groove 210 is the same as the size of the lead 320, for example, when the groove 210 is a triangular prism, the lead 320 may be a triangular prism. For another example, referring to fig. 5 to 7, the groove 210 is configured as a quadrangular prism, that is, a cuboid, and the pins 320 are also configured as a cuboid with the same shape and size, so that the processing difficulty is easily reduced and the manufacturing cost of the COB display screen is reduced by configuring the groove 210 and the pins 320 of the cuboid.

It can be appreciated that after the two pins 320 are respectively inserted into the two grooves 210, the outer side walls of the pins 320 are mutually attached to the inner side walls of the corresponding grooves 210, and the bottom surface of the chip body 310 and the top surface of the bonding pad 200 are mutually attached, that is, the volume of the pins 320 is equal to that of the corresponding grooves 210, so that when reflow soldering is performed, after the pins 320 are melted, molten liquid is contained in the grooves 210, the mobility of the molten liquid is small under the limit action of the grooves 210, the probability that the molten liquid drives the chip body 310 to move is small, the LED chips 300 can be ensured to be kept at accurate positions after die bonding is completed as much as possible, the probability that the LED chips 300 deviate is reduced, the positions, the heights, the angles and the like of all the LED chips 300 are highly consistent, and the light color consistency of the COB display screen is improved.

In addition, the contact area between the pin 320 and the bonding pad 200 can be increased by the arrangement of the groove 210, for example, when the groove 210 is cuboid, the five surfaces of the pin 320 and the five surfaces of the groove 210 are in one-to-one correspondence and contact with each other, so that the effectiveness and reliability of the electrical connection between the pin 320 and the bonding pad 200 can be improved, the probability of dark lamps and dead lamps of the LED chip 300 caused by the occurrence of cold welding of the LED chip 300 can be reduced, and the COB display screen has better display reliability.

In another embodiment of the present application, referring to fig. 5 to 7, a first limiting bump 400 is further protruding on the substrate 100, the first limiting bump 400 is located between two bonding pads 200 connected to the same LED chip 300, and a top surface of the first limiting bump 400 is flush with a top surface of the bonding pad 200.

Specifically, the first limiting protrusion 400 may be made of the same material as the substrate body, or may be made of a different material from the base body, and the first limiting protrusion 400 may be integrally formed or separately formed with the substrate body, which is not limited in this embodiment.

The COB display screen provided in this embodiment is provided with the first limit bump 400 between the two bonding pads 200 connected to the same LED chip 300, and defines the top surface of the first limit bump 400 to be flush with the top surface of the bonding pad 200, so that the two pins 320 of the LED chip 300 can be well isolated from each other, and the two bonding pads 200 connected to the LED chip 300 are isolated from each other, so as to avoid the occurrence of a short circuit due to the mutual conduction of two poles of the LED chip 300; on the other hand, the top surface of the first limiting protrusion 400 is limited to be flush with the top surface of the bonding pad 200, so that the top surface of the first limiting protrusion 400 can be mutually abutted with the bottom surface of the chip body 310, thereby providing support for the LED chip 300 and improving the structural stability of the LED chip 300.

In another embodiment of the present application, referring to fig. 5 to 7, a second limiting protrusion 500 is further protruding on the substrate 100, and the second limiting protrusion 500 is located between two sets of bonding pads 200 connected to different LED chips 300.

Specifically, the second limiting protrusion 500 may be made of the same material as the substrate body, or may be made of a different material from the base body, and the second limiting protrusion 500 may be integrally formed or separately formed with the substrate body, which is not limited in this embodiment.

The COB display screen provided in this embodiment is provided with the first spacing protrusion 400 between two groups of bonding pads 200 that different LED chips 300 are connected, can isolate the pin 320 of different LED chips 300 from each other well to isolate two bonding pads 200 that different LED chips 300 are connected from each other, avoid the short circuit to appear in different LED chips 300, promote the reliability and the stability of COB display screen.

In another embodiment of the present application, the base plate 100 and the first limit protrusion 400 are integrally formed. By this arrangement, the structural strength of the substrate 100 can be increased, and the processing process can be simplified.

In another embodiment of the present application, the substrate 100 is integrally formed with the second limiting protrusion 500. By this arrangement, the structural strength of the substrate 100 can be increased, and the processing process can be simplified.

In another embodiment of the present application, referring to fig. 6 and 7, the cob display further includes a solder resist ink layer 600, where the solder resist ink layer 600 is disposed on the substrate 100 and surrounds the outer sides of the bonding pad 200, the first limit bump 400 and the second limit bump 500; the top surface of the solder resist ink layer 600 is flush with the top surface of the pad 200, which can protect the circuit on the substrate 100 and also can isolate the circuit on the substrate 100 from the pad 200.

In another embodiment of the present application, the COB display further includes an encapsulation layer (not shown, the same applies below) covering exposed surfaces of the substrate 100, the LED chip 300, and the bonding pad 200. The LED chip 300 and the circuitry on the substrate 100 may be further protected, and the encapsulation layer may be made of epoxy, silicone, polyethylene terephthalate (Polyethylene Terephthalate, PET) film, etc., and may be a single layer or multiple layers, although in some embodiments, the encapsulation layer may not be provided.

The application also provides a display device which comprises the COB display screen.

Specifically, the display device may be a smart phone, a mobile game machine, a tablet computer, a monitoring device, a billboard, or the like, which is not limited in this embodiment.

Since the display device adopts all embodiments of the COB display screen, the display device has at least all the beneficial effects of the embodiments, and will not be described in detail herein.

The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application.

Claims (10)

1. A COB display screen, characterized in that, COB display screen includes:

A substrate;

A plurality of bonding pads which are arranged on the top surface of the substrate at intervals;

the LED chips comprise a chip body and two pins arranged on the bottom surface of the chip body, the two pins are respectively and electrically connected with the two bonding pads, and the melting point of each pin is lower than that of each bonding pad.

2. The COB display screen of claim 1, wherein the pins are tin pins or tin alloy pins.

3. The COB display screen of claim 1, wherein the top surface of each of the bonding pads is provided with a groove; the two pins are respectively inserted and matched with the two grooves, and the shape and the size of each pin are the same as those of the corresponding groove.

4. The COB display screen of claim 3, wherein the recess is prismatic, pyramid-shaped, truncated cone-shaped, cylindrical or hemispherical in shape.

5. The COB display screen of claim 1, wherein a first spacing protrusion is further protruding on the substrate, the first spacing protrusion is located between two bonding pads connected to the same LED chip, and a top surface of the first spacing protrusion is flush with a top surface of the bonding pad.

6. The COB display screen of claim 5, wherein a second spacing protrusion is further provided on the substrate, and the second spacing protrusion is located between two sets of bonding pads connected to different LED chips.

7. The COB display screen of claim 6, wherein the base plate and the first limit protrusion are integrally formed; and/or, the substrate and the second limiting protrusion are integrally formed.

8. The COB display screen of claim 6, further comprising a solder resist ink layer disposed on the substrate and surrounding the pad, the first spacing bump, and the second spacing bump; the top surface of the solder resist ink layer is flush with the top surface of the bonding pad.

9. The COB display screen of any one of claims 1-8, wherein the substrate comprises a substrate body and a conductive layer disposed on the substrate body, the substrate body being a resin plate or a glass plate; the COB display screen further comprises an encapsulation layer, and the encapsulation layer covers the conductive layer, the LED chip and the exposed surface of the bonding pad.

10. A display device, characterized in that it comprises a COB display as claimed in any one of claims 1 to 9.