A Low Cost Self-Adaptive Screening Method Based on Automatic Test Equipment for Low Dropout Voltage Regulators in Mass Production

Abstract

The low-dropout (LDO) regulator is an important component in power management IC (PMIC) chips and is widely utilized in electronic modules, such as mobile processors and Internet of Things (IoT) devices. To ensure the proper functionality of these modules, automatic test equipment (ATE) is typically used to test and calibrate LDO modules in the mass production stage. During the test process, the presence of pollutants in the test environment or inappropriate test settings can cause a discrepancy between the expected performance of the chip and its actual output. When conventional ATE test methods fail to identify these types of risks, this study proposes a novel self-adaptive screening method that enhances the possibility of screening out weak chips without the need for additional testing hardware or stages. This screening method accumulates and analyzes effective test data measured by ATE in real time, and derives a dynamic test limit to screen weak chips by performing systematic statistical analysis on the collected data, combined with the chip’s practical application requirements and tolerance. During the experimental stage, the author selected a chip lot and applied the proposed testing method. The results showed that 90.91% of escape defective chips were successfully screened, with a reasonable yield impact of 3.38%, compared to the traditional ATE test methodology which had a low capture rate.

Keywords

• Automatic test equipment (ATE)
• low-dropout (LDO) regulator
• self-adaptive method
• outlier elimination