<p>This present study employs comprehensive wavelet analysis to investigate pressure drop signals during subcooled flow boiling within a straight-through microchannel heat sink (MCHS). The research proposes the use of a flow restrictor (FR) to address the flow boiling instability, exploring its impact across a broad range of heat fluxes (15–80 W/cm²) and mass fluxes (320 and 520 kg/(m²·s)) in a high aspect ratio configuration with 44 parallel micro-channels (230 μm in width, 500 μm in height) utilizing degassed DI water as the coolant. The decomposed pressure signals reveal the contribution of various frequency components to the overall system dynamics, aiding in identifying dominant frequencies associated with flow boiling phenomena. The study demonstrates the effectiveness of the flow restrictor in mitigating flow boiling instability and enhancing heat transfer efficiency. The analysis of pressure drop fluctuations showcases the altered power spectrum behaviour and improved stability with the use of flow restrictor. The results present detailed power magnitude and dominant frequency ranges for different mass and heat fluxes, offering essential information for optimizing the heat transfer processes in the MCHS.</p>