X-ray flat panel detectors (FPDs) have been widely used for inspecting electronic packaging to detect defects and contaminations. In FPDs, scintillating materials convert X-ray into visible light, and an a-Si photodiode array converts the light into electrons for imaging. However, the spatial resolution of FPDs needs to be improved because light spreading inside the scintillator causes crosstalk with adjacent a-Si pixels, which degrades the resolution.
In this study, a scintillator was pixelated with a pixel pitch identical to that of an as a-Si photodiode array, using a barrier rib structure to limit light spreading, this helped improve the spatial resolution. The pixelated scintillator was aligned with an 83 μm pixel pitch of an a-Si photodiode array and set as an FPD. The FPD with an 83 μm pitch-pixelated scintillator exhibited a high modulation transfer function (MTF) >0.90 at 2 cycles/mm. The MTF value was almost equal to the maximum value that can be theoretically achieved. Thus, the FPD with the pixelated scintillator can be used for high-spatial-resolution X-ray inspection.
