10 Ohm ferrite bead at 100 MHz — a low-impedance noise snubber
The BLM15AG100SN1D presents 10 Ohms impedance at 100 MHz — that is a soft ferrite bead, not a high-impedance blocker. At 100 MHz the bead behaves as a lossy inductor, dissipating high-frequency noise as heat rather than reflecting it. Below 10 MHz the impedance drops below 1 Ohm, so it leaves the DC rail undisturbed while shaving 10-30 dB of noise at the switching frequency of a nearby regulator or clock line.
1A continuous with 25mOhm DCR — power-rail safe
Rated 1A continuous with a maximum DC resistance of 25mOhm. The power dissipation at rated current is 25 mW, well within the 0402 body's thermal budget even at 125°C ambient. This bead sits comfortably on a supply trace feeding a modest IC. The ferrite material's impedance curve shifts with temperature — expect roughly 15-20% impedance drop at 125°C versus room temperature, but the 10 Ohm floor still provides effective filtering.
0402 footprint — layout considerations
The small footprint demands tight placement — keep the bead within 5 mm of the IC power pin for effective decoupling. The termination pads are nickel-barrier plated; standard Sn-Pb or SAC solder profiles in reflow work without special bake steps.