LED packaging technology
According to different application needs, LED chip can be made by a variety of packaging different structure and appearance of the device, to produce a variety of color temperature, color index, variety and specifications of LED products. Whether the package with a pin, LED can be divided into pin-type packaging and surface mount package two types. Conventional low-power LED package are: DIP DIP, SMD LED, Piranha LED and PCB integrated package [1]. Power LED is the core of future semiconductor lighting, its packaging is the focus of people's current research. Here are a few major packages to explain the form:
(1) Pin-type package using lead frame as a variety of package appearance of the pin. Round-pin LED is a commonly used package. This package commonly used epoxy resin or silicone resin as the encapsulation material, the chip about 90% of the heat from the lead frame to the printed circuit board (PCB), and then distributed to the surrounding air [2]. The diameter of the epoxy resin is 7mm, 5mm, 4mm, 3mm and 2mm and other specifications. The emission angle (2θ1 / 2) ranges from 18 to 120 °.
(2) Surface Mount Package It is an important package that appears after the pin package. It uses a plastic leaded chip carrier (PLCC), the LED chip on the top of the groove, the bottom sealed with metal chip pins. LED surface mount package, a better solution to the brightness, viewing angle, flatness, consistency and reliability issues, LED packaging technology is an important development direction.
(3) power LED package power LED sub-ordinary power LED (less than 1W) and tile power LED (1W and above) two. Among them, tile-level power LED is the core of future lighting. Single-chip tile power LED is the first by the United States Lumileds company in 1998 produced LUXEON LED, this package is characterized by the use of thermoelectric separation in the form of flip chip (Flip Chip) with silicon carrier welding in the heat sink, And the use of reflective cups, optical lenses and flexible transparent plastic and other new structures and new materials