JST's PH, XH and ZH families are the small-pitch wire-to-board connectors inside consumer devices, battery packs, LED modules and countless PCB-based products. They look interchangeable to the eye and are not interchangeable in fact — each has its own pitch, terminal and process requirements. This guide helps you specify them correctly and shows what quality production of these assemblies involves.
The Family Differences
- XH (2.5mm pitch): the workhorse of the three — robust contact, positive side-locks, current ratings comfortably above the others. Default choice when board space allows.
- PH (2.0mm pitch): denser packaging with side-entry and top-entry options; the standard for battery leads in consumer products and compact modules.
- ZH (1.5mm pitch): the densest of the family for true space-constrained boards; contacts and housings are delicate, and process discipline matters most here.
Using the correct family matters electrically (current rating) and mechanically (mating retention), and using genuine or verified-compatible terminals matters absolutely: the terminals are family-specific and a wrong terminal either fails to crimp correctly or fails to seat.
Crimp Requirements: The Whole Ballgame
Small-pitch assemblies succeed or fail at the crimp. The terminals are small, the wire range narrow, and the failure modes — nicked strands from over-stripping, under-crimps with high resistance, over-crimps with fractured strands, insulation crimped over conductors — all pass casual inspection. Production quality comes from: dedicated applicators per terminal family, crimp-height verification per setup, pull-force sampling per lot, and cross-section checks when qualifying new wire-terminal combinations. Hand-crimping these terminals at volume produces exactly the intermittent field failures that make device brands miserable — our connector detection analysis covers why.
Keying and Orientation
Small-pitch housings offer limited keying; design practice compensates: polarized pinouts where possible, color-coded wires matched to silkscreen, and assembly aids (orientation markings on housings) in the harness drawing. Reverse-insertion in a battery circuit is not a theoretical risk — specify against it deliberately.
Current, Voltage and Practical Limits
Respect the family ratings: these are signal and light-power connectors. Battery and motor circuits at the top of a family's rating deserve the next size up; pushing ratings produces warm contacts that age into intermittents. Voltage is rarely the limit at these pitches; current and retention are.
Production Process at Kaweei
Kaweei produces PH/XH/ZH assemblies with automated cut-strip-crimp lines calibrated per terminal family, verified seating, length-tolerance control and 100% electrical test — serving consumer, IoT, LED and battery product makers at prototype and volume scales. Send your pin count, pitch family and wire spec to our engineering team; for the sealed version of small-pitch connections, see our waterproof assembly guide.