Molex is the American half of the wire harness world. Where JST dominates board-level and small-battery work, Molex carries most of the current in PC power supplies, white goods, industrial automation, and automotive ECUs. Roughly 20% of our wire harness output ships with Molex connectors on at least one end. MicroFit 3.0 and MiniFit Jr. together cover most of it, with Pico-Blade, Mega-Fit, and automotive MX150 making up the rest. MOQ 100 sets, first samples 7–10 days.
Molex Connector Series — What We Build With
Molex has been making connectors since 1938 and today covers everything from sub-1 mm pitch to 10 mm industrial power. The series we work with most often:
| Series | Pitch | Current Rating | Typical Use |
|---|---|---|---|
| PicoClasp | 1.0 mm | 1.5 A | Ultra-compact board-to-wire, phone internals |
| Pico-Blade | 1.25 mm | 2 A | Laptop internals, IoT devices, wearables |
| KK | 2.5 / 2.54 mm | 3 A | Classic PCB terminals, legacy and new designs |
| MicroFit 3.0 | 3.0 mm | 5–8.5 A | General-purpose industrial, small motors, power distribution |
| MiniFit Jr. | 4.2 mm | 9–13 A | PC ATX power, white goods, appliances |
| MiniFit Sr. | 4.2 mm | 14 A | Higher-current version of MiniFit Jr. |
| Mega-Fit | 5.7 mm | 23 A | Server power, data centers, industrial large loads |
| MX150 | 3.5 mm Sealed | 14 A | Automotive ECU, sealed environment |
| Mini50 | 1.27 mm | 2.5 A | Automotive low-current signaling, dense harnesses |
Others — SL, SPOX, PanelMate, Stac64, and legacy Molex part numbers — we build on request. Send us the part number if you have it, or we cross-reference from drawing dimensions.
Molex vs JST — Which One Do You Need?
Both are industry leaders, but they’re positioned differently. In practice, the choice often comes down to the reference design you’re matching, not technical merit:
- Consumer electronics boards — JST PH (2.0 mm) dominates; Molex Pico-Blade (1.25 mm) shows up in premium products.
- Small battery packs — JST XH and EH are the defaults. Molex MicroFit 3.0 appears in some larger battery applications.
- Industrial power distribution — Molex MicroFit 3.0 and MiniFit Jr. are more common. JST VH appears but less often in industrial settings.
- PC internal wiring — MiniFit Jr. owns this category. ATX power standard has used MiniFit Jr. for over 20 years.
- Automotive — Molex MX150 and Mini50 are Tier-1 standards for ECU wiring. JST appears in some interior electronics but rarely in powertrain.
- Server and data center power — Mega-Fit (23 A) is the go-to for AI server power distribution.
If you’re designing from scratch and cost-sensitive, JST is usually cheaper for low-power consumer work. For higher current or automotive, Molex is typically specified by the reference design and it’s not worth fighting that decision.
Molex Wire Harness Specifications We Support
| Parameter | Range |
|---|---|
| Supported Series | PicoClasp, Pico-Blade, KK, MicroFit, MiniFit, Mega-Fit, MX150, Mini50 (others on request) |
| Pin Count | 2 to 24 (higher on request for MicroFit / MiniFit) |
| Wire AWG | 30 AWG to 10 AWG (depending on series and current) |
| Terminal Plating | Tin (standard), gold (specified by drawing) |
| Wire Insulation | PVC, silicone, Teflon, cross-linked polyethylene (XLPE) |
| Cable Length | 50 mm to 3 meters (longer on engineering review) |
| Branch Count | 1 (assembly) to 12+ (multi-branch harness) |
| Operating Temperature | -40 °C to +105 °C (standard), higher with Teflon wire |
| Sealed Variants | MX150, MX120 IP67-rated for automotive |
| Compliance | RoHS, REACH, UL 1007/1061, AEC-Q200 for automotive, UL 758 for appliance |
| Workmanship | IPC/WHMA-A-620 Class 2 default, Class 3 on request |
| MOQ | 100 sets standard, lower for prototypes |
For sealed automotive harnesses (MX150, MX120), we work with the CPA (Connector Position Assurance) and TPA (Terminal Position Assurance) features to meet Tier-1 requirements. Tell us the target vehicle program and we’ll scope the build.
Typical Applications
Our Molex harness production splits across these main categories:
PC and workstation internal wiring. MiniFit Jr. for ATX power, PCIe power, and drive power connectors. This is a legacy category — the designs haven’t changed much in 20 years — but volume is steady because every PC and server needs these connections.
Server power and data center infrastructure. Mega-Fit for rack PSU output, MiniFit Jr. and MiniFit Sr. for lower-current branches. With AI server buildouts, Mega-Fit volume has grown significantly over the past two years.
White goods and home appliances. MiniFit Jr. for motor wiring, control board interconnects, and main power distribution. Refrigerators, washing machines, HVAC — all standardized around the 4.2 mm family decades ago.
Industrial automation. MicroFit 3.0 for sensor-to-controller wiring, motor drive connections, and small-to-medium current distribution inside industrial enclosures. Often combined with IDC terminals and ring terminals in multi-branch harnesses. See our industrial wire harness page for more on this category.
Automotive ECU and sealed wiring. MX150 and MX120 for ECU connectors in body control, powertrain, and sensor networks. Sealed IP67 construction handles underhood heat and moisture. IATF 16949 workflow with PPAP documentation. See our automotive wire harness page for full automotive scope.
Medical equipment. MicroFit 3.0 and Pico-Blade for internal wiring in diagnostic equipment, imaging systems, and laboratory automation. ISO 13485 workflow on these programs. See our medical cable assembly page for the full medical scope.
Robotics and factory equipment. Mixed-series harnesses combining MicroFit signal wiring, MiniFit power, and D-sub or M12 circular connectors at cabinet entry points. High-flex wire for moving axes, shielded constructions for motor drive signals.
Why SZFRS for Molex Harness Work
Molex work lives or dies on two details: terminal crimp quality and housing assembly. Both fail in ways that pass electrical continuity but cause real field issues later. Our approach:
Authorized Molex distribution. We source from authorized channels — Digi-Key, Arrow, Avnet, or Molex direct for volume programs. Gray-market Molex parts exist and can fail crimp validation. We don’t use them.
Series-specific crimp tooling. MicroFit, MiniFit, Mega-Fit, and MX150 each require different crimper dies and calibration. We maintain dedicated setups for each major series. Generic multi-purpose crimpers produce inconsistent crimps that eventually fail thermal cycling.
Pull force validation. Every new Molex program starts with pull force testing on first article samples. We measure against Molex-published targets and adjust tooling if results are marginal.
Sealed connector expertise (CPA / TPA). For MX150 and MX120 automotive work, we follow the CPA/TPA installation procedure per Molex’s technical specification. These secondary locking features are often skipped by inexperienced assemblers but are mandatory for Tier-1 qualification.
Cross-compatibility with JST and Hirose equivalents. For clients not locked to Molex specifically, we can cross-reference JST, Hirose, or TE equivalents at quote stage. Sometimes a different vendor gives better cost or availability without meaningful spec difference. See our capabilities page for tooling and testing equipment.
IPC/WHMA-A-620 workmanship. Class 2 default, Class 3 for automotive and medical. Full documentation on our quality and certifications page.
Our Molex Wire Harness Manufacturing Process
- Drawing review and Molex part number validation. Correct series, pin count, terminal plating (tin vs gold), housing orientation verified against customer BOM.
- Material sourcing. Molex connectors from authorized distribution. Wire from UL-recognized suppliers with appropriate AWG and insulation spec.
- Cut and strip. Automated cutters set to ± 1 mm tolerance. Strip length per Molex terminal specification (each series has its own strip target).
- Crimping. Series-specific tooling with weekly calibration. Crimp height measured on first article and periodic production samples.
- Terminal insertion and housing lock. Terminals inserted into housing per pin-out drawing. For sealed automotive connectors (MX150), CPA and TPA installed after terminal insertion verified.
- Harness assembly. For multi-branch builds, jig board assembly per drawing. Branch routing, cable ties, and protective sleeving applied per customer spec.
- Testing. 100% continuity. Pull force sampling per IPC/WHMA-A-620. Hi-pot testing for harnesses with insulation spec. Sealed connector integrity check on MX150 work.
- Packaging. Heat-shrink labels, part number marking, reel packaging for high-volume, tray packaging for harness programs.
Frequently Asked Questions
What’s the difference between MicroFit 3.0 and MiniFit Jr.?
MicroFit is 3.0 mm pitch, rated 5–8.5 A depending on terminal size and plating. MiniFit Jr. is 4.2 mm pitch, rated 9–13 A. MicroFit is used for signal and small-power distribution; MiniFit Jr. handles PC power, appliance motors, and higher-current work. They’re not interchangeable — different pin spacing, different terminal sizes.
Can you build MX150 automotive harnesses?
Yes. MX150 and MX120 work runs through our IATF 16949 automotive process. We handle CPA and TPA installation per Molex spec, sealed-connector integrity testing, and AEC-Q200 wire selection. PPAP documentation available on request. Tell us the Tier-1 program and we scope accordingly.
What’s the difference between Molex KK 2.5 mm and KK 2.54 mm?
Both exist and both are common. KK 2.5 mm (0.098 inch) uses metric spacing. KK 2.54 mm (0.1 inch) matches 0.1-inch breadboard grid and is dimensionally interchangeable with many generic 0.1-inch headers. Drawings often specify “KK 254” or “KK 100” — same family. When sourcing, specify which variant to avoid confusion.
Can you build Mega-Fit harnesses for server power applications?
Yes. Mega-Fit is increasingly common in AI server and data center power distribution due to 23 A per pin rating. We stock common MicroFit and MiniFit Jr., plus MegaFit and MX150 for higher-spec work. Wire AWG for Mega-Fit builds typically runs 10–14 AWG to handle the current without derating.
Can you substitute Molex with JST or Hirose equivalents?
Often yes, if you’re not locked to Molex by drawing or Tier-1 spec. MicroFit 3.0 has close equivalents from JST (various series) and Hirose DF3. MiniFit Jr. has fewer direct equivalents. We cross-reference at quote stage and flag any electrical or mechanical differences for your approval.
What’s your MOQ and lead time for Molex harnesses?
100 sets standard. Simple 2–4 pin harnesses sometimes run 200–300 pieces for cost efficiency. Prototype batches of 10–50 pieces available. First samples 7–10 days; production 10–14 days. Automotive MX150 programs add 5–7 days for PPAP documentation.
Do you use tin or gold plating on Molex terminals?
Per your drawing. Tin is standard for most power and general-purpose work. Gold plating is specified for low-current signal work, connect-disconnect cycling requirements, or corrosive environments. Specify the terminal part number — Molex sells both tin and gold versions of most terminals.
Can you ship Molex harnesses internationally?
Yes. Europe, the US, India, Southeast Asia, and the Middle East are regular destinations. FedEx, DHL, UPS for samples and smaller orders; ocean freight for production volume. DDP, DAP, or EXW per preference.
Related Wire Harness Products
If you’re comparing wire harness options or need specialty builds:
- Wire Harness — full overview of our wire harness capabilities.
- JST Connector Harness — smaller, consumer-focused connector family, cost-effective alternative.
- Automotive Wire Harness — IATF 16949 certified builds including MX150 programs.
- Battery Pack Harness — specialty lithium battery wiring.
- Industrial Wire Harness — factory automation and machinery wiring.
Ready to Quote Your Molex Harness Project?
Send us Molex part numbers, pin count, wire AWG, and branch structure. Or a drawing, or a sample to cross-reference. We’ll come back with a quote, tooling status, and lead time within 24 hours. From 100-piece prototypes to 50,000-unit automotive programs, Molex is daily work here.