Molex Micro-Fit 3.0 Connector: Part Numbers, Specs, Crimping & Selection Guide
The Molex Micro-Fit 3.0 is a 3.00mm pitch wire-to-wire and wire-to-board power connector rated at 5A per circuit, designed for compact, high-density power distribution in demanding environments. It is one of the most widely specified connectors in server power supplies, industrial automation, medical devices, automotive electronics, and consumer appliances.
Despite its ubiquity, the Micro-Fit 3.0 part numbering system — with plug housings (43020), receptacle housings (43025), male terminals (43031), female terminals (43030), panel mount variants, single-row and dual-row configurations, and circuit counts from 2 to 24 — is a frequent source of confusion for engineers and procurement teams alike.
This guide provides a complete reference based on official Molex product documentation and datasheet SD-43020-001: part number decoder, full circuit count selection table, compliance data, crimping procedure, and a direct comparison with Molex Mini-Fit Jr. and JST VH. Ready to source? Shop Molex Micro-Fit 3.0 connectors at Keszoox.
Molex Micro-Fit 3.0 Official Specifications
| Parameter | Value |
|---|---|
| Pitch | 3.00 mm |
| Current Rating | 5.0A per circuit (at 20°C ambient) |
| Voltage Rating | 600V AC/DC (UL), 250V AC/DC (CSA) |
| Operating Temperature | −40°C to +105°C |
| Housing Material | Nylon (PA), UL 94V-0, Black |
| Contact Material | Copper alloy, tin-plated |
| Mating Type | Wire-to-Wire / Wire-to-Board |
| Row Configuration | Single Row (43640/43645) or Dual Row (43020/43025) |
| Circuit Count | 2–24 (dual row); 1–12 (single row) |
| Panel Mount | Optional (integrated ears on plug housing) |
| Polarized | Yes (keyed housing prevents mis-mating) |
| Low-Halogen | Yes (since inception, per IEC 61249-2-21) |
| RoHS | Compliant per EU 2015/863 |
| REACH SVHC | Not Contained per D(2025)7771-DC (04 Feb 2026) |
| UL Recognition | E29179 |
| CSA Certification | LR19980 |
| IPC Compliance | IPC 1752A Class C and Class D |
Molex Micro-Fit 3.0 Product Family Overview
The Micro-Fit 3.0 system consists of four core components. A complete mated connector pair requires one plug housing, one receptacle housing, and the appropriate crimp terminals for each.
| Component | Series Number | Description | Mates With |
|---|---|---|---|
| Plug Housing (Dual Row) | 43020 | Wire-side plug, dual row, 2–24 circuits, optional panel mount | 43025 |
| Receptacle Housing (Dual Row) | 43025 | Wire-side or board-side receptacle, dual row, 2–24 circuits | 43020 |
| Plug Housing (Single Row) | 43640 | Wire-side plug, single row, 2–12 circuits | 43645 |
| Receptacle Housing (Single Row) | 43645 | Wire-side or board-side receptacle, single row, 2–12 circuits | 43640 |
| Male Crimp Terminal | 43031 | Male (plug-side) crimp contact, AWG 18–24 | 43030 |
| Female Crimp Terminal | 43030 | Female (receptacle-side) crimp contact, AWG 18–24 | 43031 |
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Molex Micro-Fit 3.0 Part Number Decoder
Plug Housing (43020)
Format: 43020–[circuit count][panel mount option]. The 4-digit suffix encodes the circuit count and panel mount option (last digit 0 = no panel mount, 1 = panel mount ears).
| Part Number | Circuits | Panel Mount | Rows |
|---|---|---|---|
| 43020-0200 | 2 | No | Dual |
| 43020-0201 | 2 | Yes | Dual |
| 43020-0400 | 4 | No | Dual |
| 43020-0401 | 4 | Yes | Dual |
| 43020-0600 | 6 | No | Dual |
| 43020-0601 | 6 | Yes | Dual |
| 43020-0800 | 8 | No | Dual |
| 43020-0801 | 8 | Yes | Dual |
| 43020-1000 | 10 | No | Dual |
| 43020-1200 | 12 | No | Dual |
| 43020-1600 | 16 | No | Dual |
| 43020-2000 | 20 | No | Dual |
| 43020-2400 | 24 | No | Dual |
Receptacle Housing (43025)
The 43025 receptacle housing follows the same circuit count convention as the 43020 plug. It is the mating half and can be used wire-to-wire or mounted on a PCB: 43025-0200 (2-circuit), 43025-0400 (4-circuit), 43025-0800 (8-circuit), 43025-1200 (12-circuit), 43025-2400 (24-circuit).
Male and Female Crimp Terminals: 43031 and 43030
| Part Number | Type | Plating | AWG | Housing |
|---|---|---|---|---|
| 43031-0001 | Male crimp terminal | Tin | 18–24 | 43020 plug |
| 43031-0002 | Male crimp terminal | Gold | 18–24 | 43020 plug |
| 43030-0001 | Female crimp terminal | Tin | 18–24 | 43025 receptacle |
| 43030-0002 | Female crimp terminal | Gold | 18–24 | 43025 receptacle |
Terminal locking tabs must be fully seated before mating. A partially seated terminal will not make reliable electrical contact and may cause intermittent failures or arcing under load.
Circuit Count Selection Guide
| Circuits | Plug P/N | Receptacle P/N | Max Current | Typical Application |
|---|---|---|---|---|
| 2 | 43020-0200 | 43025-0200 | 10A total | Single power rail, fan connector |
| 4 | 43020-0400 | 43025-0400 | 20A total | Dual power rail (V+ / GND ×2) |
| 6 | 43020-0600 | 43025-0600 | 30A total | ATX-style power, mixed signal/power |
| 8 | 43020-0800 | 43025-0800 | 40A total | Server power distribution, motor drives |
| 10 | 43020-1000 | 43025-1000 | 50A total | Multi-rail power supply output |
| 12 | 43020-1200 | 43025-1200 | 60A total | High-density server backplane |
| 14–24 | 43020-1400 to 43020-2400 | 43025-1400 to 43025-2400 | 70–120A total | Industrial control, large power harnesses |
Important: The 5A per circuit rating applies at 20°C ambient. Derate in high-temperature environments or bundled harnesses. Refer to Molex application specification 430450001-AS for full derating curves.
Panel Mount Option Explained
- Panel mount ears are molded into the plug housing body — no separate hardware required
- The ears lock on the side opposite the punch side of the housing
- Recommended panel thickness: 0.762mm to 3.175mm (0.030” to 0.125”)
- Panel cutout dimensions specified per circuit count in Molex drawing SD-43020-001
- Panel mount variants available for 2, 4, 6, 8, 10, 12, 20, 22, and 24 circuit counts
Compliance and Certifications
| Standard | Status |
|---|---|
| EU RoHS (2015/863) | Compliant |
| China RoHS (SJ/T 11365-2006) | Compliant |
| REACH SVHC | Not Contained per D(2025)7771-DC (04 Feb 2026) |
| Low-Halogen | Since inception, per IEC 61249-2-21 |
| UL Recognition | E29179 |
| CSA Certification | LR19980 |
| IPC 1752A | Class C and Class D |
| Flammability | UL 94V-0 |
Low-Halogen note: Low-Halogen since inception per IEC 61249-2-21 — not a later reformulation. Suitable for halogen-sensitive applications without reformulation date verification.
Compatible Off-the-Shelf Cable Assemblies
| Part Number | Description | Use Case |
|---|---|---|
| 214755 | Female-to-Female OTS Cable Assembly | Wire-to-wire extension harness |
| 214756 | Female-to-Pigtail OTS Cable Assembly | Custom termination on one end |
| 245132 | Micro-Fit 3.0-to-Micro-Fit 3.0 Overmolded Adapter | Adapter / extension with strain relief |
| 214762 | Pre-Crimped Lead, Male-to-Male | Individual wire with male terminals on both ends |
| 214763 | Pre-Crimped Lead, Male-to-Pigtail | Individual wire with male terminal on one end |
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How to Crimp Molex Micro-Fit 3.0 Terminals
Required Tools
- Molex crimp tool: 638190900B or equivalent ratchet crimping tool with Micro-Fit 3.0 die set
- Wire: AWG 18–24 stranded copper
- Wire stripper calibrated for AWG 18–24
- Terminal extraction tool: 63811-8700 or equivalent
Crimping Procedure
- Select terminal: 43031-0001 (male) for plug housing 43020; 43030-0001 (female) for receptacle housing 43025
- Strip wire: Strip 2.5–3.0mm. Do not nick conductor strands
- Position in crimp tool: Conductor barrel and insulation barrel must align with die jaws
- Insert wire and crimp: Squeeze ratchet tool until it releases. Both barrels crimped in a single stroke
- Inspect: All strands captured, none protruding from front. Pull-test at 20N minimum
- Insert into housing: Push from rear until locking tab clicks audibly
- Verify retention: Tug each wire firmly. No terminal should move
⚠️ Critical: Do not mate until all terminals are fully seated. Partially seated terminals cause intermittent failures or arcing under load.
Molex Micro-Fit 3.0 vs Mini-Fit Jr. vs JST VH
| Specification | Micro-Fit 3.0 | Mini-Fit Jr. | JST VH |
|---|---|---|---|
| Manufacturer | Molex | Molex | JST |
| Pitch | 3.00 mm | 4.20 mm | 3.96 mm |
| Current Rating | 5A per circuit | 9A per circuit | 7A per circuit |
| Voltage Rating | 600V (UL) | 600V (UL) | 250V |
| Operating Temp | −40°C to +105°C | −40°C to +105°C | −25°C to +105°C |
| Max Circuits | 24 (dual row) | 24 (dual row) | 10 |
| Wire AWG | 18–24 | 18–24 | 18–20 |
| Panel Mount | Yes (optional) | Yes (optional) | No |
| Low-Halogen | Yes (since inception) | Yes | No (standard) |
| Best For | Compact power, server, medical | High-current, ATX PSU, industrial | Field wiring, prototyping |
Choose Micro-Fit 3.0 over Mini-Fit Jr. when board space is limited and 5A per circuit is sufficient — 30% higher density at 3.00mm vs 4.20mm pitch. Choose Mini-Fit Jr. when current per circuit exceeds 5A or for ATX power supply applications (9A per circuit standard). Choose JST VH when field wiring without crimping tools is required (Quick-connect VHR housing).
➡️ Shop Molex Mini-Fit Jr. Connectors | Shop JST VH 3.96mm Connectors
Common Applications
- Server and data center power: Blade server power distribution, storage backplane, GPU power rails
- Industrial automation: PLC power buses, servo drive power input, sensor power distribution
- Medical devices: Internal power harnesses in imaging equipment, patient monitoring, surgical tools
- Telecommunications: Base station power distribution, rack-mount equipment internal wiring
- Consumer appliances: High-end appliance internal wiring, HVAC control boards
- Automotive electronics: In-cabin power distribution, infotainment system power harnesses
- Test and measurement: Bench power supply output connections, ATE fixture wiring
Frequently Asked Questions
What is the Molex Micro-Fit 3.0 pitch? The Molex Micro-Fit 3.0 uses a 3.00mm pitch. This is distinct from Molex Mini-Fit Jr. (4.20mm) and Molex PicoBlade (1.25mm). The 3.00mm pitch provides a good balance of current capacity and connector density for power applications.
What is the current rating of Molex Micro-Fit 3.0? According to the official Molex application specification (430450001-AS), the Micro-Fit 3.0 is rated at 5.0A per circuit at 20°C ambient. Derate in high-temperature environments or bundled harnesses.
What is the difference between 43020 and 43025? 43020 is the plug housing (wire-side, with male terminals 43031). 43025 is the receptacle housing (wire-side or board-side, with female terminals 43030). A complete connection requires one 43020 plug and one 43025 receptacle.
What terminals does Molex Micro-Fit 3.0 use? 43031 male crimp terminals for the 43020 plug housing, and 43030 female crimp terminals for the 43025 receptacle housing. Both rated AWG 18–24. Tin-plated (43031-0001 / 43030-0001) and gold-plated (43031-0002 / 43030-0002) variants available.
What does the panel mount option mean on Molex Micro-Fit 3.0? Panel mount variants (last digit = 1, e.g. 43020-0201) include integrated ears that lock the plug housing into a panel cutout, preventing pull-out under vibration. Recommended panel thickness: 0.762–3.175mm per Molex drawing SD-43020-001.
Is Molex Micro-Fit 3.0 RoHS compliant? Yes. Compliant with EU RoHS 2015/863, China RoHS, and REACH SVHC (Not Contained per D(2025)7771-DC, 04 Feb 2026). Low-Halogen since inception per IEC 61249-2-21.
What is the difference between Molex Micro-Fit 3.0 and Mini-Fit Jr.? Micro-Fit 3.0: 3.00mm pitch, 5A per circuit. Mini-Fit Jr.: 4.20mm pitch, 9A per circuit. Mini-Fit Jr. is the ATX power supply standard. Micro-Fit 3.0 is preferred for compact, high-density designs. The two series are not cross-compatible.
What wire gauge does Molex Micro-Fit 3.0 use? AWG 18–24 stranded copper wire. AWG 20–22 is most common for 5A applications. Use AWG 18 for full 5A per circuit over longer wire runs.
How do I release a terminal from a Molex Micro-Fit 3.0 housing? Use Molex terminal extraction tool 63811-8700 or equivalent. Insert from the mating face to depress the locking tab, then pull the wire from the rear. Do not use sharp tools that could damage the housing or latch.
What is the difference between single-row and dual-row Micro-Fit 3.0? Dual-row (43020/43025) supports 2–24 circuits in a compact two-row layout. Single-row (43640/43645) supports 1–12 circuits in a single row. Dual-row is more common for power distribution; single-row is used when connector height or single-row PCB layout is required.
Shop Molex Micro-Fit 3.0 Connectors at Keszoox
Keszoox stocks Molex Micro-Fit 3.0 connectors including plug housings (43020), receptacle housings (43025), male crimp terminals (43031), female crimp terminals (43030), and pre-crimped cable assemblies. All RoHS compliant and Low-Halogen. In stock, ships worldwide.
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Related guides: Molex Connector Types Guide | Molex PicoBlade 1.25mm Guide | How to Identify Molex Connectors | JST VH Connector Model Numbers Guide