What This Impact Header Is — and Where It Goes
The Molex 761551103 is a 120-position backplane header from the Impact 76155 series, built for high-speed differential-pair routing. It packs 40 differential pairs across 12 rows at a tight 0.053" (1.35 mm) pitch — the column pitch that defines the Impact family's density. The 30V rating signals this is a signal-path connector, not a power interconnect: every contact carries a differential signal, and the 30.0µin (0.76µm) gold plating on the mating surface is specified for the mating-cycle count a backplane lives through.
The 0.053" (1.35 mm) pitch is the tightest in the Impact series — the 12-row column layout puts 120 positions in a footprint that fits a standard backplane slot pitch. For the board layout engineer, that pitch sets the breakout channel width and the number of routing layers needed to escape all 40 differential pairs. The 12 rows are arranged as six columns of 20 contacts each (10 columns × 12 rows = 120 positions), with the differential pairs occupying the inner rows and the outer rows carrying ground returns to control crosstalk. The press-fit through-hole footprint matches the standard Impact backplane keep-out; the hole size and pad diameter are defined in the Molex product drawing for the 76155 series.
This header mates with the Impact 76155 series right-angle receptacle (female) that carries the same 0.053" column pitch and 12-row layout. The press-fit header is the backplane side; the receptacle is the daughtercard side. The mating interface is keyed by the Impact housing geometry — a standard 76155-series backplane receptacle with the same 10-column × 12-row arrangement is the correct mating half. No cross-mating with other Impact pitch variants (0.075" or 0.085") — the column pitch difference prevents it.
Construction and Compliance Details
The black housing colour is cosmetic but consistent across the 76155 series, which helps visual inspection during assembly.