关键词: 电源IC, 板上驱动（DOB）封装LED, 亮度下降, 失效分析

Abstract: The failure phenomenon of the LED light source with the driver-on-board (DOB) packageis confirmed by basic electrical testing, and then the basic circuit structure schematicisobtained by X-ray non-destructive testing of the internal structure. Oscilloscope test iscarried out on each discrete part of the LED light sourcecircuit respectively, and the failure part is confirmed to be the power supply IC. Through physical opening of the package and combining with scanning electron microscope (SEM), focused ion beam-scanning electron microscope (FIB-SEM) and energy dispersive spectrometer (EDS) tests, it is analyzed that the root cause of the decrease in the brightness of the LED light source is the abnormal power supply IC.The reason for the failure of the power supply IC is that the Fe element residue and contamination trigger etching abnormality, and the Fe element-containing foreign matter is embedded inside the chip, leading to the abnormality of the etching line inside the chip, which results in the failure of the internal functional unit.Ultimately, the function of the IC is deviated from the design, and the IC partially or completely fails.

Key words: power supply IC, Driver-on-board (DOB) package LED, luminance droop, failure analysis