Design Engineering Note: Molex MLX 43255-0099 12-Circuit Header
The Molex MLX 43255-0099 is a 12-position, 4-row shrouded header from the MLX 43255 series, designed for board-to-cable/wire interconnect in automotive, general-purpose, and industrial applications. It carries a 6.35mm pitch and 6.35mm row spacing, with a locking ramp for vibration-resistant mating and a board guide for alignment during assembly. Rated 9 A per circuit at 600 V, with a wide operating temperature range of -55°C to 105°C, this header is built for moderate power distribution in environments that see temperature swings and mechanical vibration. The 137.8 µin (3.50 µm) tin plating on both the mating and post surfaces provides a cost-effective contact finish for harness applications where the connector is mated infrequently — think underhood engine harnesses or industrial control cabinets. Through-hole solder termination with a 0.170" (4.32 mm) post length suits standard PCB thicknesses.
The 6.35 mm pitch and 4-row layout mean this header occupies a wider board footprint than a 2-row equivalent — plan for a keep-out zone that accommodates the full 0.550" (13.97 mm) insulation height and the locking ramp overhang. The 600 V rating is line-to-line, not line-to-ground — the 4-wall shrouding and 6.35 mm pitch provide the creepage distance for that voltage in pollution degree 2 environments. Tin plating on the mating surface is adequate for the typical mating cycle count in harness applications (50–100 cycles), but if your design requires frequent field servicing or high-cycle automated mating, consider the gold-plated variants in the MLX 43255 series.