Dual In-Line Package (DIP) LEDs contain two connecting pins that are mounted through-hole to a printed circuit board (PCB).
DIP LEDs have a higher optical decay, lower colour rendering index (CRI), and lower efficiency than the more recent SMD LED technology. However, DIP LEDs are often still used in larger pixel pitch outdoor LED displays that require a higher brightness than SMD can provide.
Surface Mounted Device (SMD) LEDs are the more recent, resilient, efficient, and longer lasting technology for LED displays.
SMD parts can be made smaller and thinner because the part is only soldered to the “surface” of one side of the circuit board. SMD screens usually use 3-in-1 LEDs. With one 3-in-1 RGB LED unit per pixel, there are three tiny LED chips sealed inside a single part. Therefore, the color blends better, and the image appears sharper.
SMD LEDs are also available in "Black" variants. These have a tanned front to reduce surface reflections, which results in a darker screen, deeper black levels and a much higher contrast ratio. Typically black SMDs are more expensive and less bright but very effective in concerts and outdoor applications especially under direct sunlight.
The newest Chip on Board (COB) technology presents many improvements over standard SMDs.
This new technology can offer wider viewing angles and also provide the benefit of being dustproof, shockproof and waterproof making it more rigid to prevent damage of LED elements.
Another notable feature is the reduction of the moire effect due to the flat and even face.