How to Pick the Right JST Connector for PCB Harness

Choosing the right JST connector for a PCB harness may seem straightforward; however, it requires careful consideration. Still, it can quickly become a headache without the proper guidance—especially when dealing with custom JST cables that need to match specific layouts or electrical specifications. From pitch sizes to locking mechanisms, each detail matters when it comes to ensuring signal reliability and mechanical fit.

In this guide, we’ll break down the key factors to consider when selecting the ideal JST connector for your PCB cable harness project.

Table of Contents

1. Compare JST Series

1.1 PH Series (2.0 mm pitch)

PH connectors feature a 2.0 mm pin spacing and compact housing, making them ideal for signal-level wiring in densely packed PCBs. They carry up to 2 A at AWG 24 and are rated for 100 V AC/DC, with a temperature range of –25 °C to +85 °C.

1.2 XH Series (2.5 mm pitch)

With a 2.5 mm pitch, the XH series can handle higher currents (3 A at AWG 22) and voltages of up to 250 V AC/DC. Their robust housing supports operation from –25 °C to +85 °C, making them a workhorse for power and control signals.

1.3 SM Series (2.5 mm pitch, wire-to-wire)

SM connectors employ a friction-lock latch for vibration resistance. They support a maximum of 3 A at 250 V and are common in automotive or drone harnesses where secure retention is critical.

1.4 SH/ZH Series (1.0–1.5 mm pitch)

For ultra-compact applications, SH (1.0 mm) and ZH (1.5 mm) offer minimal footprints but limit currents to about 1 A and voltages to 50 V. Their fine pitch suits miniaturised electronics but demands precise crimping.

1.5 VH Series (3.96 mm pitch)

VH connectors serve heavy-current needs—up to 10 A at AWG 16 and 250 V—with a secure locking device and wide contact spacing to manage higher power safely.

2. Match Pitch to Application

High-Density Boards: Choose SH/ZH (1.0–1.5 mm) for tight layouts, knowing you’ll cap out at ~1 A per circuit.
Mixed Signal & Power: PH (2.0 mm) and XH (2.5 mm) balance size and current, covering 2–3 A needs in consumer and light-industrial gear.
Heavy Power Feeds: VH (3.96 mm) supports thicker AWG 16–22 wires for currents up to 10 A.

3. Verify Electrical & Wire-Gauge Specs

Always consult the manufacturer’s datasheet for exact ratings. Exceeding AWG ranges can result in poor crimps or overheating. For instance, PH typically uses 24–32 AWG, XH handles 22–30 AWG, and VH accepts 16–22 AWG.

4. Evaluate Mechanical Features

Locking & Polarisation: SM’s friction latch and XH’s keyed housings prevent mis-mating and loosening under vibration.
Housing Styles: Shrouded and polarised designs guide insertion and protect contacts, reducing assembly errors.

5. Choose PCB Mount & Assembly

5.1 Mount Styles

Through-Hole (THT): Superior retention under mechanical stress, ideal for heavy cables.
Surface-Mount (SMT): Enables pick-and-place automation but may need reinforcement in vibration zones.
Right-Angle vs. Vertical: Right-angle headers help manage cable routing in tight enclosures.

5.2 Crimp vs. IDC

Crimp-Style Contacts: Achieve reliable performance with proper tooling, expecting ratings of 1.0–3.0 A, depending on the series.
Insulation Displacement (IDC): Fast assembly without stripping—HR series IDC handles 2 A at AWG 24 and 250 V, with a thin, high-density design.

6. Environmental & Compliance

Temperature Range: Most series support a temperature range of –25 °C to +85 °C; some high-temperature variants extend further.
Certifications: When targeting regulated markets, look for UL, CE, and CSA marks on datasheets.

7. Selection Checklist

Series & Pitch: Match board density and current needs.
Electrical Ratings: Confirm current, voltage, and wire gauge.
Mechanical Locking: Choose latches or polarisation as needed.
Mount Style: Balance assembly method with mechanical strength.
Crimp vs. IDC: Weigh speed versus long-term reliability.
Environmental Factors: Verify temperature, vibration, and compliance standards.

Conclusion

JST connectors offer a wide variety of configurations, making them incredibly versatile for PCB harness design. But with so many options, choosing the right one can feel overwhelming. If you’re still not sure which JST connector is right for your harness—or if you’re planning to build custom JST cables tailored to your design—we’re happy to help. Our team specializes in crafting high-quality cable assemblies tailored to your exact needs.

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Alex Wang

Alex Wang is the Marketing Manager at Romtronic, with a degree in International Business and over seven years of experience in the electronic cable and wire harness industry. He leads marketing efforts across North and South America, combining deep industry knowledge with strong sales experience.

In addition to overseeing global marketing strategy, Alex is also responsible for content development and editorial coordination, ensuring that Romtronic’s messaging remains clear, consistent, and engaging. His strength in market analysis and customer-focused approach helps clients make more informed purchasing and sales decisions.