The core of the LED is just a small PN junction, and the core of an ordinary LED is only the size of a grain of sand. The LEDs we buy on the market have been packaged according to different application needs. There are two most commonly used LED packaging forms-in-line and chip (SMD), of which the in-line is currently the most widely used, so that when some enthusiasts mention LEDs, they immediately think of a tall straw hat. Something with two feet. However, with the development of SMD technology and the continuous miniaturization of products, SMD LED packaging will become the mainstream.

      1. In-line LED lamp beads-always very popular, never replaced

    Commonly used in-line packaged LED specifications are φ 3, φ5, φ8, φ10, which refers to the diameter of the in-line LED cap body (unit is mm). The most common among them is φ 5 LED products. Because the shape of the in-line LED is determined by the aperture size of the LED indicator on the shell required by the final product, you should choose according to your application when you choose. There are several designs of the in-line package to distinguish the LED polarity in appearance. As shown in Figure 5, the pin under the cut side of the monochromatic direct plug-in LED cap is the negative electrode of the LED; before welding, the short pin side of the pin is the negative pole of the LED; the housing of the monochromatic direct plug-in LED Generally, there are two kinds of colors: colored and transparent. For example, a red light plug-in LED. If the housing is also red, it is called a red-haired red LED, and if the housing is transparent, it is called a white-haired red LED. According to this statement, there are green hair green, white hair green, white hair blue, white hair white and other specifications. As shown in the figure:

 2. SMD LED-a must-have for miniature electronic products

    Commonly used SMD LED package specifications are 5050, 3528, 2835, 5630, 335 refers to the size of the SMD LED. Because the side-emitting SMD LEDs are directly mounted on the circuit board and cannot extend to the shell, the light guide component needs to guide the light to the specified position on the shell, so the general SMD LED packages are transparent shells. There are also some designers who arrange SMD LEDs into arrays to make small LED displays, which is also a usage. In the side-emitting SMD LED package, the side pin with the small green (or blue) dot is the negative electrode of the LED.