The production process of LED backlights is similar to that of CCFL backlights. The main difference is that LEDs are point light sources, while CCFLs are line light sources. In the long-term trend, LED backlight technology is expected to gradually become more popular as a replacement technology.

Let's take a preliminary look at the production process of LED backlights:

A. Cleaning: PCBs or LED lead frames are cleaned using ultrasonic cleaning and then dried.

B. Mounting: After preparing the electrode on the bottom of the LED chip (large wafer) with silver adhesive, the chip is unfolded and placed on the crystal stage. The chip is moved one by one under a microscope and installed on the corresponding solder pad on the PCB or LED bracket. Silver adhesive is then sintered and cured.

C. Wire bonding: The electrodes are connected to the LED chip using aluminum wire or gold wire bonding machines as leads for injecting current. LEDs are directly mounted on the PCB, typically using aluminum wire bonding machines. (A gold wire bonding machine is required for producing white TOP-LEDs.)

D. Encapsulation: The LED chip and wire bonding are protected using epoxy resin through dispensing. The dispensing on the PCB has strict requirements for the shape after the glue is cured, which directly affects the brightness of the finished backlight. This process also involves applying phosphor (for white LEDs).

E. Soldering: If the backlight source is SMD-LED or other packaged LEDs, they need to be soldered onto the PCB before the assembly process.

F. Film cutting: Various diffusion films and reflector films required for the backlight source are die-cut using a punch press.

G. Assembly: Various materials of the backlight are manually installed in the correct positions according to the drawings.

H. Testing: Check the photometric parameters and uniformity of the backlight source.

I. Packaging: The finished products are packaged and stored according to requirements.

Currently, LED backlights can be classified according to their types: RGB-LED and white LED.

The former utilizes dynamic partition backlight technology and three-color RGB LED light sources. It has made significant advancements in color and contrast compared to traditional backlight sources and is commonly used in high-end television products with costs generally above 3W.

The latter is a more common type of LED backlight and is widely used in notebook computers and LCD displays. White LED backlights usually extract light from the edge of the display, which is different from RGB LEDs and traditional backlights that emit light from the back.

According to the position of the backlight, LED backlight modules can be divided into two categories: bottom-firing and edge-lit. They can be further classified as bottom-firing RGB-LED, bottom-firing white LED, and edge-lit white LED.

Differences between RGB-LED and white LED: RGB LEDs have slightly better color gamut performance, but the drawback is higher cost, making it difficult for average consumers to afford finished televisions. On the other hand, white LED light sources, although slightly inferior in color gamut to RGB LEDs, offer higher contrast and technological cost advantages that RGB-LEDs cannot match.

Differences between bottom-firing and edge-lit: Edge-lit LEDs emit light from the sides of the device, projecting the light onto the panel through a built-in high-transmittance light guide plate. The limitation of LCD thickness is the thickness of the fluorescent lamp, and the edge-lit source is positioned on the sides of the device, occupying no space in the TV thickness.

Compared to edge-lit sources, bottom-firing LED backlights can dynamically control the backlight. This means that when displaying dark scenes, only the necessary backlight areas need to be adjusted (appearing as black or darker parts on the screen). Localized illumination can present high-quality image effects with natural contrasts between light and dark.