I. Introduction
LED applications have been extended to various fields, including LCD Backlight, mobile phone Backlight, digital light, art lighting, building lighting and stage lighting control, home lighting, etc. According to the DIGITIMES Reasearch survey, demand growth in 2010~2015 is as high as 30%. This has led to a significant increase in LED production capacity. With the complication of LED application environment, LED downstream manufacturers are increasingly demanding upstream grain quality. For example, the voltage value of LED antistatic test (ElectrostaTIc Discharge, ESD) is gradually increased from the original 4kV requirement to 8kV. Tolerate the harsh environment of the outdoors. Therefore, the high-voltage LED anti-static test is the key module that is urgently needed to be developed in the current LED die spot measuring machine.
Static electricity in various modes in the environment, including human body static electricity or mechanical static electricity, can cause damage to the LED. When static electricity touches the two pins of the LED through induction or direct contact, the potential difference will directly act on both ends of the LED. When the voltage exceeds the tolerance of the LED, the electrostatic charge is between the two electrodes of the LED in a very short time. Discharge occurs, causing damage to the insulation of the LED, resulting in leakage or short circuit. Therefore, the Solid Electron Device Engineering Council (JEDEC22-A114E, JESD22-A115A) sets the test specifications for the human body electrostatic discharge mode (HBM) and the machine model (Machine model, MM). Ensure the quality of LED products. However, the purchase of foreign high-voltage generators with charge and discharge switching circuits, and the integration of Prober and automated mobile platform main disadvantages are slow response (0 to 4kV rise time 500ms), and the high-voltage insulation of the probe is not considered, so there is a slow classification of crystal grains. And test the wave type stability is not serious problems, often break down LED or charge and discharge modules, as shown in Figure 1, or the machine is not high-voltage testability, is still damaged by high-voltage static electricity after shipment, directly affecting the quality of LED products. In addition, the measurement time of 20,000 to 40,000 wafers on the wafer often takes more than one hour, and it is necessary to shorten the inspection time to increase the production capacity. Therefore, this paper develops a high-speed multi-voltage switching high-voltage generating component design using a dynamic range control circuit and PID feedback control through a high-speed multi-voltage switching LED wafer electrostatic measurement module, with a high-voltage dynamic range (250V-8kV) and High-speed static test (80ms), as shown in Figure 2A and Figure 2B, to meet the needs of the domestic LED industry, to achieve the goal of reducing costs and self-made key modules.
Figure 1 LED is damaged by static electricity
Figure 2A High-speed large dynamic range electrostatic measurement module short-circuit electrostatic test current waveform
Figure 2B High-speed multi-voltage switching high-voltage generating component electrical test output voltage waveform
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