Surface mount package

In 2002, SMD LED was gradually accepted by the market and gained a certain market share

SMD is in line with the development trend of the entire electronic industry, and many manufacturers have introduced such products.

Early SMD LED mostly adopts SOT-23 improved type with transparent plastic body, which is wrapped in coiled containers. On the basis of SOT-23, the former is monochromatic and the latter is bicolor or tricolor. In recent years, SMD LED has become a development hotspot, which has solved the problems of brightness, visual angle, flatness, reliability, consistency, etc. It uses lighter PCB board and reflective layer materials, requires less epoxy resin to be filled in the display reflective layer, and removes heavier carbon steel material leads. By reducing the size and weight, it can easily reduce the product weight by half, and finally make the application more perfect, especially for indoor use, Semi outdoor full color display application.

Table 3 shows several sizes of common SMD LEDs and the best viewing distance calculated according to the size (plus the necessary gap). The bonding pad is an important channel for heat dissipation, and the SMD LED data provided by the manufacturer are all based on 4.0 × Based on 4.0mm pads, reflow soldering can be used to design pads equal to pins. Ultra high brightness LED products can be packaged with PLCC (plastic package with lead chip carrier) - 2, and the high brightness tube core can be assembled by a unique method. The thermal resistance of the product is 400K/W, and it can be welded according to CECC mode. Its luminous intensity is 1250 mcd under 50 mA driving current. The character height of 7-segment 1-bit, 2-bit, 3-bit and 4-bit digital SMD LED display device is 12.7mm, and the display size selection range is wide. The PLCC package avoids the manual insertion and pin alignment process required by the seven segment digital display of pins, and meets the production requirements of the automatic pickup and mounting equipment. The application design space is flexible and the display is bright and clear. The multi-color PLCC package is equipped with an external reflector, which can be easily combined with the LED or photoconductor. The reflective type is used to replace the transmission type optical design, providing unified lighting for a wide range of areas. The power SMD LED package working under 3.5V and 1A driving conditions is developed.