X-rays possess extremely strong penetrating power. Different material densities and thicknesses absorb X-rays to varying degrees. By analyzing the intensity changes of X-rays after passing through a sample, grayscale contrast images are formed to identify internal structures. Based on material density characteristics, PCBA components can be divided into four categories: tin-lead alloy solder joints (high density, appear dark in images); metal packaging shells, ceramic packaging, chips (medium density); plastic packaging materials, silicon materials (low density, appear light in images); void, crack defects and PCB vias (X-rays pass through completely, appear brightest).