Luminescence principle of LED patch bead: the terminal voltage of PN junction forms a potential barrier. When the forward bias voltage is added, the barrier drops, and most carriers in the P and N regions diffuse to each other. Since electron mobility is much larger than hole mobility, a large number of electrons will be diffused to the P region, forming an injection of minority carriers in the P region. These electrons recombine with the holes in the valence band, and the resulting energy is released as light energy. This is the principle of PN junction luminescence.
It is believed that LED package
is of great significance to the quality of LED bead:
I. necessity of LED package
The LED chip is just a tiny solid. Its two electrodes are visible under a microscope. In the manufacturing process, besides welding the two electrodes of the LED chip to lead out the positive electrode and the negative electrode, the LED chip and the two electrodes also need to be protected.
Ⅱ. The function of LED package
The development of LED package
technology with low thermal resistance, excellent optical properties and high reliability is the only way for the new LED to become practical and enter the market. LED package
technology is mostly developed and evolved on the basis of semiconductor separation device packaging technology. The core of the ordinary light-emitting diode is sealed in the package body to protect the chip and complete the electrical interconnection.
Ⅲ. LED package method selection
The photon emitted by the pn junction of the LED is non-directional, that is, it has the same probability to be emitted in all directions, so not all light generated by the chip can be emitted. How much light can be emitted depends on the quality of semiconductor materials, chip structure, geometry, packaging materials and internal materials.