JST SM Connector: Complete Guide to Wire-to-Wire Crimping, Part Numbers & Panel Layout
Search for "JST SM connector" and you'll find almost nothing useful — a few forum posts, scattered distributor listings, and no practical engineering guide. Yet the JST SM series is one of the most capable 2.5mm pitch wire-to-wire connectors available: it features an arm lock mechanism for positive retention, supports panel mounting in panels from 0.5mm to 2.0mm thick, and is rated for 3A per contact at 250V AC/DC. It is UL Recognized (E60389) and RoHS2 compliant.
This guide covers everything engineers and makers need: what makes the SM different from other JST 2.5mm connectors, complete electrical specifications, all SMR receptacle and SMP plug housing part numbers from 2P to 18P in black and white, terminal selection, panel layout dimensions for all circuit counts, and a step-by-step crimping guide.
What Is the JST SM Connector? Key Differentiators
The JST SM series is a 2.5mm pitch wire-to-wire crimp connector designed for high-density, small-current applications. Three features set it apart from other JST 2.5mm connectors:
1. Wire-to-wire only — no PCB header required or available
Unlike the JST XH (wire-to-board) or JST XA (wire-to-wire and wire-to-board), the SM is a dedicated wire-to-wire system. The receptacle housing (SMR) and plug housing (SMP) connect directly to each other. There is no PCB header variant. This makes the SM the right choice when you need to connect two wire harnesses without involving a PCB at all.
2. Arm lock mechanism
The SM uses an arm lock (latch) on the plug housing that positively engages the receptacle. This provides a secure, audible click on mating and prevents accidental disconnection — unlike the friction-fit JST XH which has no positive lock. The arm lock can be released by pressing the latch tab.
3. Panel mounting capability
The SMR receptacle housing can be mounted directly in a panel cutout. Panel thickness range: 0.5mm to 2.0mm. This allows the receptacle to be chassis-mounted while the SMP plug connects from the wire harness side — a configuration common in consumer electronics, appliances, and industrial enclosures.
Additional features:
- High contact pressure — phosphor bronze contacts maintain reliable connection over temperature cycles
- Highly reliable housing construction — PA 6, UL94V-0 flame retardant
- Available in black and white (natural) for color-coded assemblies
- 2P to 18P circuit count range
➡️ Browse all JST SM assemblies: JST SM 2.5mm Cable Assembly Collection at Keszoox — PVC and silicone wire options, single-head and extension configurations.
JST SM Electrical Specifications
| Parameter | Specification |
|---|---|
| Pitch | 2.5mm |
| Connector type | Wire-to-wire crimp (disconnectable) |
| Current rating | 3A AC/DC max. (2–12P) / 2A AC/DC max. (18P) |
| Voltage rating | 250V AC/DC |
| Temperature range | -25°C to +85°C (including temperature rise under rated current) |
| Contact resistance (initial) | 10mΩ max. |
| Contact resistance (after environmental test) | 20mΩ max. |
| Insulation resistance | 500MΩ min. |
| Withstanding voltage | 1,500V AC/minute |
| Applicable wire | AWG #28 to AWG #22 |
| Conductor cross-section | 0.08 to 0.33 mm² |
| Insulation O.D. | 1.2mm to 1.8mm |
| Panel thickness (panel mount) | 0.5mm to 2.0mm |
| Locking mechanism | Arm lock (positive latch) |
| Housing material | PA 6, UL94V-0, black or white (natural) |
| Contact material | Phosphor bronze, tin-plated (reflow treatment) |
| UL recognition | E60389 |
| RoHS compliance | Yes (RoHS2) |
| Circuit count range | 2 to 18 circuits |
Important note on 18P current rating: The 18-circuit SM housing (SMR-18V-B/N, SMP-18V-BC/NC) is rated at 2A per contact, not 3A. All other circuit counts (2–12P) are rated at 3A per contact. Do not apply 3A loads to 18P assemblies.
Note on withstanding voltage: At 1,500V AC/minute, the SM matches the JST XH and XA series — significantly higher than the JST SCN board-in connector (800V). The SM is suitable for applications requiring higher isolation voltage in wire-to-wire configurations.
JST SM Crimp Terminals
The SM series uses two crimp terminals — a pin contact (SYM) for the receptacle housing and a socket contact (SHF) for the plug housing. Both cover the same wire gauge range.
| Part Number | Type | Housing | Wire Gauge (AWG) | Conductor (mm²) | Insulation O.D. (mm) | Material | Qty/Reel |
|---|---|---|---|---|---|---|---|
| SYM-001T-P0.6 | Pin contact | SMR receptacle | #28 to #22 | 0.08–0.33 | 1.2–1.8 | Phosphor bronze, Sn-plated | 8,500 |
| SHF-001T-0.8BS | Socket contact | SMP plug | #28 to #22 | 0.08–0.33 | 1.2–1.8 | Phosphor bronze, Sn-plated | 5,000 |
Terminal identification rule: SYM pin contacts go into the SMR receptacle housing (the panel-mount side). SHF socket contacts go into the SMP plug housing (the free-hanging wire harness side). Do not mix — inserting a socket contact into a receptacle housing will result in mating failure.
Crimping equipment:
- SYM-001T-P0.6 (pin): AP-K2N crimping machine, MKS-L dies, MK/SYM-001-06 crimp applicator
- SHF-001T-0.8BS (socket): AP-K2N crimping machine, MKS-L dies, MK/SHF-001-0BS crimp applicator
How to Crimp JST SM Connectors: Step-by-Step
This section answers the most common search query about the SM series: how to crimp JST SM connectors correctly. Incorrect crimping is the leading cause of SM connector failures in the field.
- Strip the wire — Strip 3.0–3.5mm of insulation from the wire end. Do not nick the conductor strands. For AWG #28–#22, use a precision wire stripper set to the correct gauge.
- Select the correct terminal — SYM-001T-P0.6 for the SMR receptacle side; SHF-001T-0.8BS for the SMP plug side. Verify before crimping — the two terminals are not interchangeable.
- Position the terminal in the crimping tool — Place the terminal in the AP-K2N crimping machine with MKS-L dies. The conductor crimp wings should align with the stripped conductor; the insulation crimp wings should align with the wire insulation.
- Insert the wire — Insert the stripped wire into the terminal so the conductor extends slightly beyond the conductor crimp wings. The insulation should be captured by the insulation crimp wings.
- Crimp — Apply the crimp. The conductor wings should fold tightly around the conductor strands without cutting them. The insulation wings should grip the insulation without crushing it.
- Inspect the crimp — Check that: (a) no conductor strands are cut or protruding from the side, (b) the insulation crimp is secure, (c) the terminal is not deformed. A pull test should withstand at least 10N for AWG #22.
- Insert the terminal into the housing — Insert the crimped terminal into the correct housing position. The terminal lance should click into place. Verify by gently pulling the wire — the terminal should not pull out.
- Verify contact position numbers — Position 1 is marked on both the SMR receptacle and SMP plug. Verify polarity before mating.
- Mate the connector — Align the SMP plug with the SMR receptacle and press together until the arm lock clicks. Verify the latch is fully engaged.
Common crimping mistakes to avoid:
- Using the wrong terminal (SYM vs SHF) in the wrong housing
- Under-stripping the wire (conductor too short for the crimp wings)
- Over-stripping the wire (bare conductor exposed beyond the insulation crimp)
- Using incorrect die settings — always use MKS-L dies with the AP-K2N for SM terminals
- Inserting the terminal in the wrong orientation (the lance must face the housing retention feature)
➡️ Need pre-crimped SM assemblies? JST SM Connector Kit with 22AWG Pre-Crimped Cables — includes SMR receptacle, SMP plug, and pre-crimped wire leads, ready to use without crimping tools.
JST SM Housing Part Numbers: 2P to 18P
SM housings are available in two colors — black (B suffix) and white/natural (N suffix for receptacle, NC suffix for plug). Housing material: PA 6, UL94V-0. All housings are RoHS2 compliant.
SMR Receptacle Housing (for SYM pin contacts — panel mount or free hanging):
| Circuits | Black | White (Natural) | Current Rating | Qty/Bag |
|---|---|---|---|---|
| 2 | SMR-02V-B | SMR-02V-N | 3A | 1,000 |
| 3 | SMR-03V-B | SMR-03V-N | 3A | 1,000 |
| 4 | SMR-04V-B | SMR-04V-N | 3A | 500 |
| 5 | SMR-05V-B | SMR-05V-N | 3A | 500 |
| 6 | SMR-06V-B | SMR-06V-N | 3A | 500 |
| 7 | SMR-07V-B | SMR-07V-N | 3A | 500 |
| 8 | SMR-08V-B | SMR-08V-N | 3A | 500 |
| 9 | SMR-09V-B | SMR-09V-N | 3A | 500 |
| 10 | SMR-10V-B | SMR-10V-N | 3A | 200 |
| 11 | SMR-11V-B | SMR-11V-N | 3A | 200 |
| 12 | SMR-12V-B | SMR-12V-N | 3A | 500 |
| 18 | SMR-18V-B | SMR-18V-N | 2A | 200 |
SMP Plug Housing (for SHF socket contacts — free hanging):
| Circuits | Black | White (Natural) | Current Rating | Qty/Bag |
|---|---|---|---|---|
| 2 | SMP-02V-BC | SMP-02V-NC | 3A | 1,000 |
| 3 | SMP-03V-BC | SMP-03V-NC | 3A | 1,000 |
| 4 | SMP-04V-BC | SMP-04V-NC | 3A | 1,000 |
| 5 | SMP-05V-BC | SMP-05V-NC | 3A | 1,000 |
| 6 | SMP-06V-BC | SMP-06V-NC | 3A | 500 |
| 7 | SMP-07V-BC | SMP-07V-NC | 3A | 500 |
| 8 | SMP-08V-BC | SMP-08V-NC | 3A | 500 |
| 9 | SMP-09V-BC | SMP-09V-NC | 3A | 500 |
| 10 | SMP-10V-BC | SMP-10V-NC | 3A | 500 |
| 11 | SMP-11V-BC | SMP-11V-NC | 3A | 500 |
| 12 | SMP-12V-BC | SMP-12V-NC | 3A | 500 |
| 18 | SMP-18V-BC | SMP-18V-NC | 2A | 200 |
Color selection guide: Black housings are standard for most applications. White (natural) housings are used where visual inspection of contact insertion is required, or for color-coded multi-connector assemblies. Both colors share identical electrical and mechanical specifications.
Panel Layout and Assembly Dimensions
The SMR receptacle housing can be panel-mounted in panels from 0.5mm to 2.0mm thick. All dimensions in mm.
| Circuits | Model No. | Panel 0.5–1.0mm (A/B) | Panel 1.0–1.5mm (A/B) | Panel 1.5–2.0mm (A/B) | |||
|---|---|---|---|---|---|---|---|
| 2 | SMP-02V-B/NC | 5.7 | 9.8 | 5.7 | 9.8 | 5.7 | 9.8 |
| 3 | SMP-03V-B/NC | 8.2 | 12.1 | 8.2 | 12.5 | 8.2 | 12.5 |
| 4 | SMP-04V-B/NC | 10.7 | 14.5 | 10.7 | 14.8 | 10.7 | 15.0 |
| 5 | SMP-05V-B/NC | 13.2 | 17.1 | 13.2 | 17.3 | 13.2 | 17.5 |
| 6 | SMP-06V-B/NC | 15.7 | 19.7 | 15.7 | 19.8 | 15.7 | 20.0 |
| 7 | SMP-07V-B/NC | 18.2 | 22.1 | 18.2 | 22.5 | 18.2 | 22.5 |
| 8 | SMP-08V-B/NC | 20.7 | 24.5 | 20.7 | 24.8 | 20.7 | 25.0 |
| 9 | SMP-09V-B/NC | 23.2 | 27.1 | 23.2 | 27.3 | 23.2 | 27.5 |
| 10 | SMP-10V-B/NC | 25.7 | 29.5 | 25.7 | 29.8 | 25.7 | 30.0 |
| 11 | SMP-11V-B/NC | 28.2 | 32.1 | 28.2 | 32.3 | 28.2 | 32.5 |
| 12 | SMP-12V-B/NC | 30.7 | 34.5 | 30.7 | 34.8 | 30.7 | 35.0 |
| 18 | SMP-18V-B/NC | 23.2 | 27.2 | 23.2 | 27.4 | 23.2 | 27.9 |
Panel mounting notes:
- Punch holes in the panel according to the sketch and table. Burrs must be removed before mounting.
- The strength of the panel must be considered when punching two or more holes side by side.
- The connector must be inserted from the same side as the hole is punched.
- SM connectors with any number of circuits can be used either panel mounted or free hanging.
JST SM vs JST XH vs JST XA: Choosing the Right 2.5mm Connector
All three are 2.5mm pitch connectors with 3A/250V ratings — but they serve fundamentally different applications. They are not interchangeable.
| Feature | JST SM | JST XH | JST XA |
|---|---|---|---|
| Pitch | 2.5mm | 2.5mm | 2.5mm |
| Current (max) | 3A (2–12P) / 2A (18P) | 3A | 3A |
| Voltage | 250V AC/DC | 250V AC/DC | 250V AC/DC |
| Temperature | -25°C to +85°C | -25°C to +85°C | -25°C to +105°C |
| Withstanding voltage | 1,500V AC/min | 1,500V AC/min | 1,500V AC/min |
| Connection type | Wire-to-wire only | Wire-to-board only | Wire-to-wire + wire-to-board |
| Locking mechanism | Arm lock (positive latch) | Friction fit (no lock) | Secure lock + contact lance |
| Panel mount | Yes (0.5–2.0mm) | No | Yes |
| Glow wire certified | No | No | Yes (IEC 60695-2) |
| Housing colors | 2 (black, white) | 1 (natural) | 1 (natural) |
| Circuit count | 2–18 | 2–16 | 2–15 |
| UL recognition | E60389 | — | — |
| Best for | Wire harness to wire harness, panel-mount enclosures | PCB wire-to-board, Arduino, 3D printers | Appliances, industrial, glow wire required |
Choose SM when: wire-to-wire connection with no PCB, positive arm lock required, panel mounting needed, up to 18 circuits, UL E60389 required.
Choose XH when: wire-to-board connection to a PCB header.
Choose XA when: glow wire certification (IEC 60695-2) or +105°C temperature rating required.
➡️ JST XH 2.5mm Complete Guide → | JST XA 2.5mm Complete Guide →
JST SM in the 2.5mm Connector Ecosystem
| Series | Type | Pitch | Lock | Panel Mount | Max Circuits | Best For |
|---|---|---|---|---|---|---|
| JST SM | Wire-to-wire | 2.5mm | Arm lock | Yes | 18 | Wire harness, panel enclosures |
| JST XH | Wire-to-board | 2.5mm | None | No | 16 | PCB connections, Arduino |
| JST XA | W-W + W-B | 2.5mm | Secure lock | Yes | 15 | Appliances, glow wire |
| JST SCN | Board-in | 2.5mm | Contact lance | No | 16 | Consumer electronics, no header |
| XHS2.5 (Yeonho) | Wire-to-board | 2.5mm | Belt lock | No | — | Vibration-resistant |
➡️ Wire-to-Board Connector Types: Complete Guide → | Common JST Connector Types → | JST SCN Board-In Guide →
How to Select the Right JST SM Connector
- Confirm wire-to-wire requirement — The SM is wire-to-wire only. If you need wire-to-board, use JST XH or XA instead.
- Determine circuit count — 2P to 12P: 3A per contact. 18P: 2A per contact. No 13–17P variants exist — jump from 12P to 18P.
- Choose housing color — Black (B/BC suffix) or white/natural (N/NC suffix). Both are electrically identical.
- Select terminals — SYM-001T-P0.6 (pin) for SMR receptacle. SHF-001T-0.8BS (socket) for SMP plug. Both cover AWG #28–#22.
- Determine mounting method — Panel mount: measure panel thickness (0.5–2.0mm) and use the panel layout table above. Free hanging: no panel preparation needed.
- Verify locking requirement — The SM arm lock provides positive retention. Confirm the arm lock tab is accessible after installation for field disconnection.
- Choose wire type — Standard PVC (UL1007, 80°C) for general use; silicone (UL3239, 200°C, 3KV) for high-temperature or high-flex applications.
➡️ Shop JST SM assemblies by wire type: JST SM 2.5mm Pre-Crimped Cable 22AWG UL1007 PVC | JST SM 2.5mm Single-Head Silicone Cable 22AWG UL3239 (200°C, 3KV) | JST SM 2.5mm Male-Female Extension Silicone Cable 22AWG UL3239
Common Applications
- Consumer electronics internal wiring — Wire harness connections inside TVs, audio equipment, and home appliances where wire-to-wire connection with positive locking is required
- Industrial enclosures and control panels — Panel-mounted SMR receptacle allows field-replaceable wire harness connections through the enclosure wall
- Automotive accessories — Wire-to-wire connections in accessory harnesses where the arm lock prevents vibration-induced disconnection
- Medical and laboratory equipment — UL E60389 recognition and positive locking suit applications requiring documented connector reliability
- High-temperature environments — Silicone cable variants (UL3239, 200°C, 3KV) extend SM assembly suitability to HVAC, motor wiring, and high-ambient-temperature enclosures. See JST SM 2.5mm Male Single-Head Silicone Cable UL3239
- High-density wiring — Up to 18 circuits in a single connector for complex wire harness assemblies in compact enclosures
Frequently Asked Questions
What is the JST SM connector?
The JST SM is a 2.5mm pitch wire-to-wire crimp connector rated for 3A AC/DC (2–12P) or 2A (18P) at 250V AC/DC, operating from -25°C to +85°C. It features an arm lock mechanism for positive retention and supports panel mounting in panels 0.5–2.0mm thick. Available in 2P to 18P in black and white. UL Recognized E60389, RoHS2. ➡️ Shop JST SM at Keszoox
How do I crimp JST SM connectors?
Use the AP-K2N crimping machine with MKS-L dies. SYM-001T-P0.6 pin contacts go into the SMR receptacle housing; SHF-001T-0.8BS socket contacts go into the SMP plug housing. Strip 3.0–3.5mm of insulation, crimp conductor and insulation wings, insert the terminal until the lance clicks, then mate the SMP plug to the SMR receptacle until the arm lock engages. See the full step-by-step crimping guide above. ➡️ Shop JST SM Connector Kit with Pre-Crimped Cables
What is the difference between JST SM and JST XH?
The SM is a wire-to-wire connector with an arm lock and panel mount capability. The XH is a wire-to-board connector requiring a PCB header, with no positive locking mechanism. Both are 2.5mm pitch, 3A/250V, but not interchangeable. ➡️ JST XH Complete Guide
What part number is a 6-pin JST SM connector?
Receptacle (black): SMR-06V-B. Receptacle (white): SMR-06V-N. Plug (black): SMP-06V-BC. Plug (white): SMP-06V-NC. Pin terminal: SYM-001T-P0.6. Socket terminal: SHF-001T-0.8BS. ➡️ Shop JST SM
Can the JST SM be panel mounted?
Yes. The SMR receptacle housing can be panel-mounted in panels from 0.5mm to 2.0mm thick. Panel hole dimensions vary by circuit count and panel thickness — see the panel layout table above. The connector must be inserted from the same side as the hole is punched, and burrs must be removed before mounting.
Why is the 18-pin JST SM rated at 2A instead of 3A?
The 18-circuit SM housing (SMR-18V-B/N, SMP-18V-BC/NC) has a reduced current rating of 2A per contact due to the higher thermal density of 18 conductors in a single housing. All other SM circuit counts (2–12P) are rated at 3A per contact. Do not apply 3A loads to 18P SM assemblies.
What terminals does the JST SM use?
SYM-001T-P0.6 (pin contact, for SMR receptacle) and SHF-001T-0.8BS (socket contact, for SMP plug). Both cover AWG #28–#22 (0.08–0.33mm²), insulation O.D. 1.2–1.8mm. Material: phosphor bronze, tin-plated. Do not mix the two terminal types within the same connector.
Is the JST SM UL recognized?
Yes. The JST SM connector is UL Recognized under file number E60389 and is RoHS2 compliant. Housing material: PA 6, UL94V-0 flame retardant.
➡️ JST XH Guide → | JST XA Guide → | JST SCN Guide → | Wire-to-Board Types → | JST Connector Types → | Shop JST SM →