LED display package device development history review

The LED package structure can be changed according to the needs of the application products. According to different application requirements, the LED chip can be packaged into different structures and appearances by various packaging methods, and the package form of the LED display device is mainly divided into direct insertion. Packaging, dot matrix packaging and surface mount packaging. In recent years, there have been COB packagings developed by enterprises, which have recently attracted wide attention from industry professionals.

1, in-line package

In-line package

The in-line package adopts a lead frame as a pin for various package appearances (commonly known as a bracket). Usually, one end of the bracket has a "bowl-shaped" structure, and the LED chip is bonded and welded in a "bowl-shaped" structure, and then potting is used. In the form of liquid epoxy resin injected into the LED molding cavity, and then inserted into the bonded LED bracket, high temperature barbecue molding, and finally die, cut into a single. In-line package is the first package structure that has been successfully put on the market, with a large variety and high technology maturity.

2, dot matrix package

Dot matrix package

The dot matrix package is formed by regularly bonding a plurality of LED chips to a micro PCB board in a matrix arrangement of 4×4.8×8, using a plastic reflective frame cover and potting epoxy resin, and the outer leads are mostly double rows. The steel pin is connected to the internal micro-PCB. Because it is packaged in a full package, its internal structure is stable and protective.

3, in-line three-in-one package

In-line three-in-one package

Through the improvement of the in-line process, the three RGB chips are sealed into a straight-line lamp, and the outdoor triad has been developed. It did not change the packaging process of the traditional straight-line lamp, but broke through in the product structure and combination, and sealed RGB in one lamp, using four lamp pins. With this type of packaging, the in-line LED display can achieve a lower density without changing the production process, and is extremely competitive in price.

4, surface mount package

Surface mount package

The surface mount package is to adhere a single or multiple LED chips to a metal bracket with a plastic "cup" frame (the outer pins of the bracket are respectively connected to the P and N poles of the LED chip), and then the plastic frame is filled. Sealed liquid epoxy resin,

It is then baked at a high temperature and finally cut into individual surface mount packages. The degree of automation is higher due to the SMT process.

5, COB package
COB package

The COB package, that is, the chip on board, is to adhere the bare chip to the interconnect substrate with conductive or non-conductive glue, and then perform wire bonding to realize electrical connection. COB combines "LED light source discrete device→MCPCB light source module" into one, directly puts the semiconductor chip on the placement, integrates it on the MCPCB to make the COB light source module, and realizes the electrical connection between the chip and the substrate by the wire stitching method. Resin coverage ensures reliability, saving labor and time, and saving on device packaging costs.

From the development history of LED display packaging, each change is a technological innovation, and it is also an embodiment of LED companies pursuing innovation and pursuing better display effects. From the perspective of in-line insertion, this is the earliest and the most widely used package form. Later, the dot matrix package has the lowest cost of raw materials and the simplest processing method, but the disadvantages are also obvious, and the color consistency is relatively poor. The mosaic phenomenon is more serious. Under the conditions of the time, dot matrix is ​​a more popular way.

Some enterprises have developed an outdoor three-in-one plug-in product by modifying the three RGB chips into a single plug-in lamp through the improvement of the in-line process. With this type of packaging, the in-line LED display can achieve a lower density without changing the production process, and is extremely competitive in price.

When the surface-mount package appeared, due to the constraints of cost factors, it has not been widely used for popularization. On this basis, the packaging method of sub-surface stickers appeared. The sub-surface sticker is actually an improvement on the single-lamp solution at that time. Its performance is different from the display effect, and the viewing angle and brightness. However, the basic difference is not big, and the advantages are obvious and the cost is low. The display effect is better.

The sub-labeling scheme is a transitional stage before the cost of surface-mounting is reduced. This is also a great progress made by people in the industry in the process of continuous exploration. In the context of the times, it has certain practical significance. However, the surface mount product has improved the display effect of the LED display.

At the beginning of the surface-mount products, due to its superior performance in various aspects, perspective, light distribution, automated production, etc., it has a place in indoor full-color display applications. In addition, in the continuous advancement of technology, surface-mount products have made great progress in terms of color and protection level, and the application of surface-mounting in outdoor applications has become more and more extensive. Now, outdoor surface-mounting has become a potential for enterprises to compete. market.

The application of COB package in lighting is now the most popular. The COB package can directly package multiple chips on a metal-based printed circuit board. Direct heat dissipation through the substrate can not only reduce the manufacturing process and cost of the bracket, but also reduce the thermal resistance. Thermal advantages. From the perspective of cost and application, COB packaging has become the mainstream of future lighting design. It is precisely because of the many advantages of COB packaging that LED display companies have turned their attention to the COB package and referenced the COB package to the LED display. In the years of research and experimentation, they have achieved good results.

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