Traditional liquid crystal displays use cold cathode fluorescent lamps (CCFL) as the backlight, which has poor color reproduction and contains mercury vapor that is harmful to the human body. Nowadays, with the development of technology, it is gradually replaced by LED backlight. The LED backlight has good color reproducibility, long life, no mercury, is good for environmental protection, and can work at low voltage, has a fast response speed, and is more convenient to control.
The backlight is divided into direct backlight and edge-light backlight according to the position of the light source. Direct-lit backlights directly place the LED light source under the light-emitting surface. The light emitted by the light source is diffused and mixed by a space distance and a diffuser before being emitted as a surface light source. Direct-lit backlights require a certain light mixing distance. The edge-lit backlight structure is more superior to the ultra-thin module design. With the "ultra-thin wind" blowing, large-size ultra-thin edge-lit LED backlights have become the research of major TV manufacturers and upstream companies. Hot spot.
The entire structure of the LED backlight includes: LED light bar, driver board, film, light guide plate, heat sink, upper frame, back plate, lens, etc. Among them, the adhesive fixation between the LED light bar and the lens has become an important process in the production process.
The light bar is generally a long strip of substrate, and the materials include: FR-4, metal, ceramic, alloy, etc., and specific placement positions are marked on the substrate, generally including 3-4 dispensing positions.
Lens, also known as LENS, materials include: PC, glass, PMMA, silica gel, etc., there are 3 or 4 pins corresponding to the glue position on the light bar, usually the size is about φ2cm, and the pin height is about 1mm.
At present, the common method of fixing LENS and light bar is to use a dispenser to dispense glue on the light bar dispensing position. The glue needs to have a relatively large viscosity to ensure that the glue type of 0.5-1mm height is maintained within 3-5min, and then the lens Put the pin into the corresponding position, insert the pin into the glue, make the glue completely cover the pin of the lens, and then solidify the glue.
1. Recommended glue point for bonding the backlight module light bar lens
According to the different processes of customers, there are two main types of LED backlight glue from Tiannuo New Material Technology: epoxy resin structural glue and ultraviolet curing glue.
1. One-component epoxy adhesive:
high viscosity, strong adhesion, good storage, can be cured at 80 ℃, no dust after curing.
2, UV curing adhesive:
High viscosity, high strength, good toughness, impact resistance, suitable for bonding LENS and substrate.
