CN218679462U

CN218679462U - PCB and display module

Info

Publication number: CN218679462U
Application number: CN202220509262.0U
Authority: CN
Inventors: 李小明; 杨贵森; 贾锐明; 徐勋明; 夏建平; 王次平
Original assignee: Shenzhen Absen Optoelectronic Co Ltd
Current assignee: Shenzhen Absen Optoelectronic Co Ltd
Priority date: 2022-03-08
Filing date: 2022-03-08
Publication date: 2023-03-21
Anticipated expiration: 2032-03-08

Abstract

The utility model provides a PCB board and display module assembly. The PCB board includes: the LED chip soldering-resistant PCB comprises a PCB substrate without solder-resistant ink, a bonding pad arranged on the PCB substrate and used for soldering an LED chip, and a nano coating fully covering the surface of the PCB substrate, wherein the surface of the nano coating is flat, the thickness of the nano coating is in a nano level, and the nano level is dozens of nanometers to hundreds of nanometers. Because the surface of the nano coating is flat, when the tin paste is printed on the surface of the nano coating, tin points are printed uniformly, the steel mesh is not influenced by the height difference between the bonding pad and the surface of the traditional PCB, gully is avoided, and the service life of the steel mesh is long.

Description

PCB and display module

Technical Field

The utility model relates to a LED display screen technical field, in particular to PCB board and display module assembly.

Background

The Mini LED display module is formed by placing 100-300 micron LED chips on a PCB pad printed with solder paste through equipment, reflowing and welding the LED chips, and molding and packaging the LED chips by packaging adhesive.

In order to protect the circuit on the PCB, a layer of solder resist ink with a thickness of 20-50 microns is printed on the circuit of the PCB (the safety performance is affected by the thickness of the solder resist ink layer being too thin). Referring to fig. 1, the thickness of the solder resist ink layer 3 causes a height difference between the pad 2 and the upper surface of the PCB board 1, resulting in an uneven appearance. Because LED chip size is little, the steel mesh thickness that the solder paste printing was used is thin, the trompil is also narrow, prevents that 3 thickness on welding ink layer lead to the difference in height on pad and PCB board surface can influence the printing of solder paste, if lead to the solder paste printing tin point inhomogeneous, influence the welding effect of chip and display module's display effect.

Meanwhile, the steel mesh is printed in the state that the height difference exists between the bonding pad and the surface of the PCB for a long time, the protruding anti-welding ink layer enables uneven gullies to appear on the surface and the back of the steel mesh, the printing effect of the tin paste is further influenced by the gullies, and the display effect of the display module is finally influenced.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a PCB board to prevent among the prior art that solder paste layer thickness leads to the problem that the tin point printing is inhomogeneous and the steel mesh gully appears.

An object of the utility model is to provide a display module assembly, it has foretell PCB board.

In order to solve the technical problem, the utility model adopts the following technical scheme:

a PCB board comprising: the LED chip soldering-resistant PCB comprises a PCB substrate without soldering-resistant ink, a bonding pad arranged on the PCB substrate and used for soldering an LED chip, and a nano coating fully covering the surface of the PCB substrate, wherein the surface of the nano coating is flat, the thickness of the nano coating is in a nano level, and the nano level is dozens of nanometers to hundreds of nanometers.

According to the utility model discloses an aspect, it lays the solder paste that is used for welding the LED chip to be the punctiform on the nanometer coating, the solder paste with the pad is corresponding and passes through nanometer coating looks interval, the material of nanometer coating is rosin, active resin or imidazole.

According to one aspect of the invention, the imidazole includes benzotriazole, alkyl imidazole, benzimidazole, alkyl benzimidazole and phenyl benzimidazole.

According to one aspect of the present invention, the nanocoating is transparent or translucent.

According to one aspect of the present invention, the transparency of the nano-coating is 70% to 99%.

According to an aspect of the present invention, the thickness of the nano-coating is 50nm to 500nm.

The utility model also provides a display module, which comprises an LED chip and the PCB board; the LED chip is welded on a bonding pad on the surface of the PCB substrate through solder paste.

According to one aspect of the present invention, the display module further comprises a black ink layer and a sealant layer; the black ink layer is printed on the PCB welded with the LED chip through ink jet, the black ink layer is a hollow pattern, the black ink layer covers the nano coating, and the hollow part of the black ink layer corresponds to the position of the LED chip; the sealing adhesive layer covers the black ink layer and the outer side of the LED chip.

According to an aspect of the present invention, the thickness of the black ink layer is 10um ~ 80um.

According to the utility model discloses an aspect, display module assembly is applied to Mini LED display screen.

According to the above technical scheme, the utility model provides a pair of PCB board has following advantage and positive effect at least:

the surface of the nano coating is flat. Therefore, when the solder paste is printed on the surface of the nano coating, the solder points are printed uniformly, the steel mesh is not influenced by the height difference between the bonding pad and the surface of the traditional PCB, gullies are avoided, and the service life of the steel mesh is long.

Drawings

Fig. 1 is a schematic structural view of a PCB having a solder resist ink layer according to the related art.

Fig. 2 is the embodiment of the present invention is a schematic structural diagram of a PCB without a solder mask ink layer.

Fig. 3 is the embodiment of the utility model provides an in the schematic diagram of LED chip welding at the PCB board.

Fig. 4 is a schematic structural diagram of an LED display module according to an embodiment of the present invention.

The reference numerals are explained below:

100-display module, 1-PCB board, 11-PCB substrate, 111-semi-cured layer, 112-copper foil circuit layer,

12-nano coating, 2-bonding pad, 3-solder mask ink layer, 4-LED chip, 5-black ink layer and 6-adhesive layer.

Detailed Description

Exemplary embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It is to be understood that the invention is capable of other and different embodiments and its several details are capable of modification without departing from the scope of the invention, and that the description and drawings are to be regarded as illustrative in nature and not as restrictive.

This embodiment provides a PCB board and display module assembly to solve current PCB board and influence the printing of tin cream by preventing welding ink layer thickness, and then influence the welding effect of LED chip and the problem of display module assembly's display effect.

The LED display module 100 provided in this embodiment is applied to an Mi ni LED display screen. The Mi ni LED has a chip size of 50-200 μm, and is a product of LED miniaturization and matrixing. At present, the Mi ni LED still adopts the traditional printing technology to fix the chip on the PCB in the production process, and the requirements on the printing quality and precision become high due to the small size of the chip.

The novel PCB board of this embodiment is through improving the structure of self, and fundamentally solves the problem that the solder mask ink layer thickness of preventing of traditional PCB board leads to the difference in height on pad and PCB board surface to influence the solder paste printing.

Referring to fig. 2, fig. 2 shows a specific structure of a PCB 1 provided in this embodiment, which includes a PCB substrate 11 and a nano-coating 12 covering a surface of the PCB substrate 11.

The PCB substrate 11 is formed by pressing an epoxy resin-based prepreg and a copper foil. The substrate 11 has a prepreg layer 111 and a copper foil wiring layer 112 spaced up and down, respectively. The surface of the substrate 11 is also provided with a bonding pad 2 for welding the LED chip, and the bonding pad 2 is connected with the copper foil circuit layer 112. The copper foil circuit layer 112 is etched to form the required circuit, and the surface of the circuit is not subjected to surface treatment and printing of solder resist ink.

The nano-coating 12 is entirely coated on the PCB substrate 11 in a thin film shape. The full coverage, i.e., the nanocoating 12 covers not only the copper foil wiring layer 112 and the pads 2 but also the substrate 11 at a position without the copper foil wiring layer 112 and the pads 2.

The nano-coating 12 may be printed on the substrate 11 by a printing device, or the nano-coating 12 may be attached to the substrate 11 by spraying or dipping.

The upper surface of the formed nano coating 12 is horizontal and flat, so that a flat printing surface is provided for subsequent solder paste printing, and the printing quality is improved.

In the present embodiment, the thickness of the nanocoating 12 reaches the nanometer level, which is in the range of several tens nanometers to several hundreds nanometers. Preferably, the thickness of the nanocoating 12 may range from 50nm to 500nm.

Further, the material of the nano coating 12 is organic compound such as rosin, active resin or imidazole. When the nano-coating 12 is imidazole, the imidazole may be selected from benzotriazole, alkyl imidazole, benzimidazole, alkyl benzimidazole, or phenyl benzimidazole.

In the process of using the PCB 1 to weld the LED chip 4, the tin paste is printed on the nano coating 12 in a dotted manner through the steel mesh, the tin paste is printed uniformly in tin dots, the position of the tin paste corresponds to that of the bonding pad 2, and the tin paste and the bonding pad are separated by the nano coating 12. In a high-temperature state of soldering, the thin nano-coating 12 is easy to chemically react with the soldering flux in the solder paste, and in the reaction process, the part (corresponding to the position of the bonding pad 2) of the nano-coating 12 in contact with the solder paste is decomposed and evaporated, so that the part of the nano-coating 12 is quickly removed in a short time, and the copper foil circuit layer 112 originally covered by the nano-coating 12 is exposed. Thus, the exposed clean substrate surface (pad 2) is immediately bonded to the molten solder in an extremely short time to form a strong solder joint, and the LED chip 4 is soldered to the pad 2.

Referring to fig. 3, fig. 3 shows an LED display module 100 provided in the present embodiment, which mainly includes an LED chip 4 and a PCB board 1. Wherein the LED chip 4 is soldered at the pad on the exposed surface of the PCB substrate 11 by solder paste.

In the present embodiment, the nanocoating 12 is transparent or semi-transparent, and the transparency of the nanocoating 12 is 70% to 99%, so as to facilitate the printing of the solder paste at the position corresponding to the pad.

Preferably, the finished PCB 1 adopts a transparent nano coating 12, the transparency of the coating is 96%, the thickness of the coating is 350nm, and the material of the coating is imidazole phenyl benzimidazole.

The PCB 1 is composed of a PCB substrate 11 and a coating 12 with a nanometer thickness instead of the PCB 1 substrate and the solder resist ink layer 3 with the thickness of 20-50 microns in the prior art, so that the problems existing in printing are solved, and meanwhile, the manufacturing cost of the PCB 1 is also reduced.

Referring to fig. 4, the display module 100 of the present embodiment further includes a black ink layer 5 and a sealant layer 6.

The black ink layer 5 is printed on the PCB board 1 to which the LED chip 4 is soldered by ink-jet printing. The black ink for ink-jet printing is made of one or more of epoxy resin, acrylic resin, epoxy modified acrylic resin and the like.

The thickness of the black ink layer 5 is 10 um-80 um.

The black ink layer 5 does not completely cover the PCB board 1. The black ink layer 5 is a hollow pattern, and the hollow parts of the black ink layer 5 correspond to the positions of the LED chips 4 one by one.

In other words, the black ink layer 5 avoids the LED chip 4 and covers the nano-coating 12 left by soldering. And the sealant layer 6 completely covers the outer side of the black ink layer 5.

The black ink layer 5 is provided to increase the blackness of the LED display module 100 without decreasing the brightness, thereby forming a more obvious contrast between light and dark, increasing the contrast of the LED display module 100, and solving the problem of poor display effect caused by the printing problem,

during manufacturing, the LED display module 100 is formed by placing a 200-micron inverted LED chip 4 on the PCB 1 pad 2 printed with solder paste through die bonding equipment, performing reflow soldering and plasma cleaning with 300W power, performing inkjet printing on a black ink layer 5 with a thickness of 40um and a pattern by using epoxy modified acrylic resin black ink, and finally performing die pressing and packaging by using epoxy resin packaging glue.

The preparation method comprises the following steps:

1. firstly, the tin paste is printed on the novel PCB 1, and the upper surface of the nano coating 12 is flat, so that the tin dots are printed uniformly.

2. The flip LED chip 4 on the blue film is placed on the PCB 1 printed with the solder paste through die bonding equipment, and the LED chip 4 is welded and fixed through backflow of a reflow oven. In a high-temperature soldering state, the thin nano-coating 12 is easy to have a complicated chemical reaction with the flux in the solder paste, and the portion (corresponding to the position of the pad 2) of the nano-coating 12 in contact with the solder paste is decomposed and evaporated, so that the nano-coating is quickly removed in a short time, and the originally covered copper foil circuit layer 112 (pad layer) is exposed.

3. And carrying out plasma treatment on the PCB 1 with the welded LED chips 4, wherein the power of the plasma treatment is 100-500W.

4. And performing ink-jet printing on the surface of the PCB 1 welded with the LED chip 4 to form a black ink layer 5 with a hollow pattern.

5. And carrying out mould pressing packaging on the PCB 1 subjected to ink-jet printing to obtain the LED display module 100, wherein the material of the sealant layer 6 is epoxy resin, organic silicon resin or organic silicon modified epoxy resin and the like.

To sum up, the utility model provides a PCB board 1 and LED display module assembly 100 have following advantage and positive effect at least:

first, the PCB 1 is composed of the substrate 11 and the nano-coating 12, rather than the PCB substrate of the prior art and the solder resist ink layer 3 of 20-50 μm. The smooth nano coating 12 can solve the problems of uneven tin point printing and gully of the steel mesh caused by the thickness of the anti-welding ink layer 3, improve the printing quality and prolong the service life of the steel mesh. Secondly, prior art relatively has increased one deck black ink layer 5 between PCB board 1 and encapsulation are glued, and under the prerequisite that does not reduce luminance, LED display module assembly 100 blackness increases to some extent, and then has increased LED display module assembly 100's contrast, promotes visual effect.

While the present invention has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration, rather than of limitation. The above-described embodiments are not to be limited to any of the foregoing details, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.

Claims

1. A PCB board, comprising: the LED chip soldering-resistant PCB comprises a PCB substrate without soldering-resistant ink, a bonding pad arranged on the PCB substrate and used for soldering an LED chip, and a nano coating fully covering the surface of the PCB substrate, wherein the surface of the nano coating is flat, the thickness of the nano coating is in a nano level, and the nano level is dozens of nanometers to hundreds of nanometers.

2. The PCB board of claim 1, wherein the nano coating is provided with a spot of solder paste for soldering the LED chip, the solder paste corresponds to the bonding pad and is spaced by the nano coating, and the nano coating is made of rosin, active resin or imidazole.

3. The PCB board of claim 2, wherein the imidazole is selected from the group consisting of benzotriazole, alkyl imidazole, benzimidazole, alkyl benzimidazole, and phenyl benzimidazole.

4. The PCB panel of claim 1, wherein the nanocoating is transparent or translucent.

5. The PCB board of claim 4, wherein the nanocoating has a transparency of 70% to 99%.

6. The PCB of claim 1, wherein the nanocoating has a thickness of 50nm to 500nm.

7. A display module comprising an LED chip and the PCB of any one of claims 1-6; the LED chip is welded on a bonding pad on the surface of the PCB substrate through solder paste.

8. The display module of claim 7, wherein the display module further comprises a black ink layer and a sealant layer; the black ink layer is printed on the PCB welded with the LED chip through ink jet, the black ink layer is a hollow pattern, the black ink layer covers the nano coating, and the hollow part of the black ink layer corresponds to the position of the LED chip; the sealing adhesive layer covers the black ink layer and the outer side of the LED chip.

9. The display module according to claim 8, wherein the thickness of the black ink layer is 10um to 80um.

10. The display module according to claim 7, wherein the display module is applied to a Mini LED display screen.