The JST B03B-WPJSS-1(LF)(SN) is a 3-position, single-row header in the WPJ series, designed for board-to-cable/wire interconnects where moisture ingress is a concern. It carries a 5.00 mm pitch, a 7 A per-circuit current rating, and a 300 V voltage rating — putting it in the medium-power, sealed-connector class. The through-hole solder termination and shrouded 4-wall housing with a latch holder make it a straightforward fit for a PCB that needs a vibration-resistant, waterproof mating interface.
Key features and what they mean for the build
The waterproof ingress protection is the headline feature — this header is built for environments where the connector sees moisture, condensation, or direct spray. The latch holder gives a positive lock with the mating receptacle, so the connection stays mated under vibration or cable tug. The 5.00 mm pitch is wide enough to keep 7 A per circuit cool without needing a large board footprint, and the 300 V rating covers most low-voltage DC and single-phase AC applications. The UL94 V-0 rated PBT housing meets the flame-retardant requirement for equipment inside an enclosure. The -25°C to 85°C operating range covers most industrial cabinet and outdoor telecom gear, though it won't handle engine-bay heat.
Mating and termination
This is the male pin header half of the WPJ board-to-wire system. It mates with the JST WPJ series receptacle housing (sold separately) that accepts crimp terminals. The latch holder on the header engages with the matching lock on the receptacle for a positive, audible click. The through-hole solder tails are tin-plated and measure 0.130" (3.30 mm) long — standard for a 1.6 mm PCB. The mated stack height is 25.3 mm, which gives clearance for the wire exit and the receptacle body above the board.