Characteristics of LED SMD products

The packaging process for surface-mounted LEDs (SMD) involves first preparing the phosphor and epoxy resin, creating a mold, and then shaping the epoxy resin with the prepared phosphor into a glue cake. This glue cake is then attached to the chip, surrounded by epoxy resin, to form an SMD-packaged LED. For example, as shown in Figure 1. A commonly seen external dimension on the market is a 50(mm)×50(mm) surface-mounted LED, which internally encapsulates three LED chips and extends six pins. These are soldered onto the surface of a PCB circuit board. Since they are directly attached to the surface of a heat sink using thermal conductive adhesive, the heat dissipation is greatly improved, leading to significantly enhanced reliability and reduced light decay. For high-power LEDs, high thermal conductivity metal-ceramic composite substrates are mainly used, which have the following main characteristics:

(1) High thermal conductivity and low thermal resistance;

(2) Thermal coefficient of expansion matching (TCE: 6.2);

(3) UV resistance;

(4) Resistance to corrosion and yellowing;

(5) Meet ROHS standards;

(6) High temperature resistance.

The thermal resistance of LED packaging has a decisive impact on the lifespan of LED chips, especially for high-current-driven LED chips. The cost and heat dissipation performance of LED packaging products depend on the structure of the packaging bracket, which is moving towards smaller size, thinner thickness, and better heat dissipation. When packaging more LED chips in a single SMD LED, heat dissipation must be considered. The important advantage of high-power SMD LEDs using high thermal conductivity metal-ceramic composite substrates is their ultra-low thermal resistance. Vishay launched a new surface-mount white LED in January 2010, using the PLCC-4 package. The optimized lead frame reduces the thermal resistance to as low as 300K/W and achieves a power dissipation of up to 200mW, allowing the device to use a driving current of up to 50mA, resulting in brightness twice that of Vishay's high-brightness sMD LED using the PLCC-2 package. Due to its small and thin size, the ultra-low thermal resistance high-power LED SMD package is more suitable for

In applications with limited space, this feature brings great convenience to many. Compared to other LED chip-type packages, it maintains the same

When the junction temperature is reduced, the requirements for heat dissipation components are lowered. When using the same heat dissipation components, the junction temperature is lowered, extending the lifespan of the LED package.