As a new lighting technology, LED has the advantages of low energy consumption, long life, small size, dimmable, flexible control and environmental protection, and its application prospects attract worldwide attention. With the decline in LED prices, the market has gradually opened, and more and more lighting products use LED as a light source. Especially in the field of road lighting, high-power LED products have become the protagonists of the market, and leds shine in the field of outdoor lighting [2]. However, with the increase in the application of LED lamps, the number of outdoor LED lamps affected by lightning surge failure is also increasing. According to the survey, most of the damaged LED outdoor lamps in the normal service life are due to the failure of the lamp power supply and LED light source caused by the overelectric stress caused by lightning surge. This not only affects the service life of lamps, but also increases the maintenance cost of enterprises. In view of this, the lightning surge resistance of LED outdoor lamps should be paid enough attention.

The lightning surge resistance of LED lamps mainly depends on two aspects:

(1) The lightning surge resistance and protection mechanism of the LED drive power supply.

(2) The ability of LED chip to resist overelectric stress.

For the LED drive power supply, two points should be used to judge its anti-lightning surge ability: (1) the anti-lightning surge ability of its own components to ensure that the power supply still works normally after lightning surge. (2) The attenuation ability of the power supply to the surge current and voltage waveform ensures that the peak current and voltage of the surge attenuation after the power supply is within the range that the LED chip can withstand. Zhang Jinjian et al. [3] from Tianjin University studied the anti-lightning surge of LED drive power supply. According to the characteristics of lightning surge, a surge protection circuit suitable for LED power supply was designed by using surge devices such as gas discharge tube, varistor and transient suppression diode, and the lightning surge generator was used for immunity experiment to test its anti-lightning performance. The experimental results show that it can resist the lightning high voltage of differential mode 1kV and common mode 2kV, and ensure the normal operation of LED power supply. However, the lightning surge resistance requirements of the LED driver power supply are determined by the ability of the LED chip to resist overelectric stress. Therefore, it is very necessary to study the ability of LED chip to resist overcurrent stress.

Based on this, this paper conducts lightning surge experiments for several types of different high-power LED chips to explore the anti-overelectric stress ability of different high-power LED chips, and provides references for the selection of the driving power and LED chips of LED outdoor lamps, as well as the design and development of anti-lightning surge surge ability, which has important practical significance.

2. Factors affecting the ability of LED chip to resist overelectric stress

First of all, the current density that the LED chip can withstand determines its ability to resist overelectric stress, and the greater the current on the unit cross-sectional area that the LED chip can withstand, the stronger its ability to resist overelectric stress. For conventional electrical conductors, the current density must be low enough to prevent the conductor from melting or fusing, or the insulation from being broken down [4]. Electromigration occurs inside the LED chip at high current density. When the conductive metal material passes through the higher current density, the metal atoms will migrate and diffuse along the direction of electron movement. Electromigration in leds allows metal atoms to spread freely from one lattice to another lattice vacancy. Take flip-structure chips as an example, when the electron flow from the interconnect lead into the convex point of eutectic alloy, due to the abrupt change in the geometry from the interconnect lead to the convex point, the current density aggregation and local Joule thermal effect will be generated at the interface [5]. The current density aggregation makes the current density distribution in the salient points and the chip and substrate leads uneven, resulting in a complex electromigration force locally at the current density aggregation, accelerating the electromigration process, and accelerating the failure of the LED.