This guide covers: connector classification by connection type and by electrical function (POINT 01); the major connector manufacturers — Japanese, global, and Asian — with their product strengths and signature series (POINT 02); the seven selection criteria that must all be evaluated for a reliable connector choice (POINT 03); connector requirements for high-reliability sectors — automotive, medical, and aerospace (POINT 04); RF and high-speed signal connector selection (POINT 05); and the procurement considerations — compatibility, EOL, counterfeit risk, and sample validation — that affect long-term supply quality (POINT 06).
The connector market encompasses tens of thousands of distinct part numbers. A practical classification framework — by the elements being connected, and by the electrical function being served — narrows the search space to the families actually relevant to a given design requirement.
By Connection Type
B-TO-B
Board-to-Board Connectors
Provide electrical connection between two PCBs. Used in module-to-baseboard configurations, stacking systems, and flexible-to-rigid board interfaces. Available in mezzanine (parallel boards), edge-card, and FPC/FFC variants. Pitch ranges from 0.4 mm (fine-pitch FPC) to 2.54 mm (standard through-hole).
Examples: Hirose FH series (FPC), Samtec BSH/BTE series, Molex SlimStack
B-TO-W
Board-to-Wire Connectors
Connect a PCB to a wire harness. The most numerically common connector type in most products — used for internal power distribution, motor connections, sensor wiring, and sub-assembly interconnects. Both PCB-mount and harness-side housings required; contact terminals are typically crimped onto wire.
Examples: JST PH/XH/ZH, Molex Micro-Fit, TE MATE-N-LOK, Hirose DF series
W-TO-W
Wire-to-Wire Connectors
Join two harness segments for in-line or extension connections. Used in cable assemblies that must be separated for servicing, manufacturing, or module replacement. Mechanically similar to B-to-W but without a PCB-mount housing; both mating halves are harness-side.
Examples: JST PA series, Molex MicroClasp, TE SL connectors
I/O
I/O and External Interface Connectors
Provide the external electrical interface of a product. Mostly standardised industry formats with defined mating compatibility across manufacturers. Mechanical durability and environmental sealing are key selection criteria — I/O connectors are directly handled by users and exposed to external environments.
Examples: USB-C, USB Micro-B, RJ45 (Ethernet), HDMI, D-Sub, 3.5 mm audio, SD card slots
POWER
Power Connectors
Designed for high current carrying capacity — typically 5A and above per contact. Contact size, terminal material, and housing material are sized for current and temperature rise. Contact resistance is critical. Designed for the mechanical stress of high mating forces required to ensure low-resistance contact.
Examples: Molex Mini-Fit Jr., Anderson Powerpole, Phoenix Contact MC series, XT60
RF / HIGH-FREQ
RF and High-Frequency Connectors
Maintain controlled characteristic impedance (typically 50 Ω) through the connector body to minimise reflection and insertion loss at RF frequencies. Inner conductor geometry, dielectric material, and outer shielding continuity are all engineered for the target frequency range. See POINT 05 for detailed comparison.
Examples: SMA, MMCX, U.FL/UMCC, N-type, SMP, SMPM, 2.92 mm (K-type)
Standardised vs. proprietary series: Standardised I/O connectors (USB, HDMI, RJ45) offer cross-manufacturer mating compatibility and high availability. Proprietary manufacturer series (JST PH, Molex Micro-Fit, TE MATE-N-LOK) offer better optimisation for specific internal wiring applications but require sourcing the matched mating half from the same manufacturer family. Confirm mating compatibility explicitly — connectors with identical pitch and appearance from different manufacturers or different series within the same manufacturer are frequently not mechanically interchangeable, even when they appear visually similar.
Connector manufacturer selection determines not just the component specifications, but the long-term supply availability, the geographic distribution network, and the technical support depth available for a design. The manufacturers below cover the majority of connector requirements in commercial, industrial, automotive, and high-reliability electronics.
Japanese Manufacturers
JST
Japan — Global
Japan Solderless Terminal. Dominant in small-pitch signal and power connectors for internal wiring. Unmatched breadth in the 1.0–2.5 mm pitch range. Excellent availability through major global distributors.
PH · XH · ZH · SH · GH · EH · SM
Hirose Electric
Japan — Global
Precision fine-pitch FPC/FFC connectors and RF board-to-board connectors. The FH, ZIF, and DF series for flat cable connections and the U.FL/UMCC for RF are industry standards in precision instruments, mobile, and communications.
FH · BM · GT · U.FL · UMCC · DF
JAE
Japan — Global
Japan Aviation Electronics Industry. Strong in automotive, industrial, and precision instrumentation connectors. Broad automotive-grade portfolio with USCAR-2 and AEC-Q200 qualified series.
WP · MX · IL · WR · DX
Global Manufacturers
TE Connectivity
USA (formerly Tyco)
Broadest overall portfolio of any connector manufacturer. Particularly strong in industrial, automotive (Deutsch brand), aerospace, and high-current applications. The MATE-N-LOK and AMP series are among the most widely specified connectors in industrial equipment globally.
MATE-N-LOK · Micro-MaTch · MTA · AMP · Deutsch
Molex
USA (Koch Industries)
Strong in board-to-board, high-density, and high-current applications. The Micro-Fit and Nano-Fit series are widely used in industrial and automotive products. High-speed signal connector portfolio growing rapidly for data centre and telecom applications.
Micro-Fit · Nano-Fit · Mini-Fit · SlimStack · MX150
Amphenol
USA — Global
Dominant in aerospace, military (MIL-DTL-38999), and industrial circular connectors. Strong in RF connectors (SMA, BNC, MMCX) and automotive (AT series, Sine Systems). One of the few manufacturers covering both mass-market and MIL-spec connector families.
MIL-DTL-38999 · SMA · MMCX · AT · ICC
Samtec
USA
Specialist in high-speed board-to-board and cable connectors for data centre, telecom, and high-performance computing. BSH, LSHM, and Edge Rate series handle multi-gigabit differential signalling. Custom and semi-custom connector solutions available.
BSH · LSHM · Edge Rate · RUSD · FireFly
Phoenix Contact
Germany
Dominant in industrial terminal blocks, PCB screw terminals, and fieldbus connectors. The COMBICON series for PCB-mount screw terminals is ubiquitous in industrial automation and control equipment. Strong in DIN rail and panel-mount industrial connectors.
COMBICON · MC · MSTB · MCRV · FRONT
Foxconn / Lotes / Speed Tech
Taiwan / China
Cost-competitive connectors for consumer electronics and cost-sensitive industrial applications. Foxconn connectors are widely used in PC motherboards and consumer electronics. Lotes specialises in high-speed and socket connectors for computing. Well-suited for high-volume, cost-driven designs.
USB · HDMI · PCIe · DIMM · CPU sockets
Connector selection failures almost always result from optimising on one or two criteria while neglecting the others. A connector chosen for its low cost and small footprint that fails its mating cycle life in the application creates far more cost than the unit price savings justified. All seven criteria below must be evaluated simultaneously.
⚡01 — Electrical Specification
Rated current (A) per contact and total; rated voltage; maximum contact resistance (mΩ); insulation resistance (MΩ); dielectric withstand voltage; and for RF connectors, characteristic impedance (Ω) and insertion loss (dB) at the operating frequency. The rated current must include margin for temperature rise — a connector rated at 3A at 20°C may be rated at 1.5A at 85°C ambient.
Rated currentContact resistanceDielectric withstandImpedance (RF)
🔧02 — Mechanical Specification
Pin count; pitch (terminal centre-to-centre spacing, mm); mating retention force (the force required to separate the mated connector, in N); mating cycle life (the number of insertion and extraction cycles the connector is rated to withstand); locking mechanism type (friction, latching, screw, push-pull); and connector entry direction (vertical / right-angle). Mating cycle life is frequently underspecified — an I/O connector on a laptop that is connected and disconnected daily will reach 500 cycles in less than 2 years.
Pitch (mm)Mating cyclesRetention forceLock type
🌡️03 — Environmental Rating
Operating temperature range (confirm both the housing material limit and the contact material limit — they may differ); IP sealing class (IP67, IP68, IP69K for harsh environment applications); vibration and mechanical shock specification per the relevant standard (USCAR-2 for automotive, IEC 60068-2 series for industrial); and flammability rating of the housing material (UL94 V-0 is the standard requirement for most electronic products). For outdoor or automotive applications, also confirm corrosion resistance to salt spray and automotive fluid exposure.
Temp rangeIP classVibration specUL94 V-0
🏭04 — Mounting Method and Assembly Compatibility
Through-hole connectors offer strong mechanical retention but require wave soldering or selective soldering — incompatible with fully automated SMT lines. Surface mount connectors are compatible with SMT reflow but have lower mechanical retention and may require adhesive for wave soldering processes. Press-fit connectors are inserted mechanically without solder, suitable for high-reliability applications that cannot be reflowed. Crimp terminals require a wire crimping tool and process validation. Confirm that the connector's mounting method is compatible with your PCB assembly line and inspection capabilities (X-ray, AOI) before finalising the selection.
THT · SMT · Press-fit · CrimpAssembly compatibility
📐05 — Size, Footprint, and Orientation
Board real estate is a finite resource. Confirm the connector's PCB footprint area and height above the board — particularly relevant for products with tight board-to-enclosure clearance or adjacent component keepout requirements. Connector entry direction (vertical: cable exits perpendicular to board; right-angle: cable exits parallel to board) affects panel clearance and cable routing. For dense designs, consider whether a smaller-pitch series can reduce footprint without compromising the electrical and mechanical requirements.
Footprint areaHeight (mm)Vertical vs right-angle
💰06 — Unit Cost and Series Availability
Standard connectors from high-volume series (JST PH/XH, Molex Micro-Fit, TE MATE-N-LOK) are significantly cheaper and more reliably available than specialty or low-volume types. Prioritise standard series at the design stage — use a specialty connector only when a standard connector genuinely cannot meet the application requirements. For cost-sensitive applications, confirm pricing at your expected production volume: many connector series have significant quantity breaks that change the economics at volumes above 1,000 pieces.
Standard series firstVolume pricingDistributor availability
📅07 — Long-Term Supply and EOL Risk
Connector EOL is disproportionately disruptive compared to most other component types, because the mating half is embedded in the customer's cable or mating housing and cannot be independently redesigned. A connector PCB change requires a cable change at the customer end. Mitigation: confirm the production lifecycle status of the series at design-in; identify a pin-compatible alternative from the same or a different manufacturer before the design is frozen; and for products with 10+ year production runs, treat connector series longevity as a qualifying criterion rather than an afterthought.
Lifecycle statusEOL riskPin-compatible alt.
Consumer and commercial electronics connectors are designed for controlled environments and moderate stress levels. Automotive, medical, and aerospace applications impose substantially more demanding requirements — and the regulatory frameworks that govern each sector specify the qualification standards that connectors must meet.
🚗
Automotive
Connectors for automotive applications must be AEC-Q200 qualified for passive components, rated for −40°C to +125°C (or +150°C for under-hood), and validated per USCAR-2 for vibration, thermal cycling, and corrosion resistance. Sealed variants (IP67 or IP69K) required for applications exposed to water. The USCAR-2 standard defines connector qualification requirements across all major NA OEMs.
TE Deutsch · Molex MX150 · Amphenol AT · JAE WP/MX · Yazaki · Sumitomo
🏥
Medical Devices
Medical connector selection requires ISO 13485 supply chain compliance, biocompatibility certification (ISO 10993) for body-contact applications, and sterilisation compatibility (autoclave, EO, gamma radiation) where applicable. Patient electrical safety requirements per IEC 60601-1 impose creepage and clearance requirements that may mandate larger-pitch or higher-specification connector series than equivalent commercial applications.
Lemo · Fischer · ODU · Hirose · TE Connectivity · ITT Cannon
✈️
Aerospace / Defence
Aerospace connectors are typically specified to MIL-DTL-38999 (circular multi-pin), MIL-DTL-26482 (bayonet coupling), or MIL-DTL-83513 (micro-D) standards. These specifications define materials, plating, vibration resistance, environmental sealing, and qualification testing to levels significantly beyond commercial standards. QPL (Qualified Products List) conformance is mandatory for defence procurement.
Amphenol · TE Connectivity (Deutsch) · ITT Cannon · Radiall · Glenair
⚠ Grade substitution is the most common high-reliability connector procurement error: A commercial-grade connector in the same physical package as an automotive- or mil-spec part is not a valid substitute. The differences — in contact plating, housing material, terminal retention force, qualification testing, and lot traceability — are not visible on receipt and are not captured by basic incoming inspection. Always verify that the part number on the purchase order and on the package references the specific qualified grade for the application, and confirm the qualification status with the manufacturer before accepting a grade that differs from the specified part number.
RF connectors maintain controlled characteristic impedance through the connector body to minimise signal reflection and insertion loss at high frequencies. The correct choice depends on the operating frequency range, the physical size constraint, and the number of mating cycles required in the application.
RF Connector Comparison
| Type | Freq. Range | Size | Mating Cycles | Typical Application |
|---|
| SMA |
DC – 18 GHz
(precision: 26.5 GHz) |
Medium |
500+ |
Test equipment, panel-mount RF ports, lab bench connections, antenna connections accessible during service |
| SMB |
DC – 4 GHz |
Small |
500+ |
Internal PCB-to-panel connections in communications equipment; snap-on coupling for quick connect/disconnect |
| MMCX |
DC – 6 GHz |
Very small |
~500 |
Industrial PCBs, WiFi/BT module antenna connections, compact communications equipment where SMA is too large |
| U.FL / UMCC |
DC – 6 GHz |
Miniature |
~30 |
Board-internal connections — module to antenna pigtail. Made once during assembly; not for field mating/demating |
| N-type |
DC – 11 GHz
(precision: 18 GHz) |
Large |
500+ |
High-power RF connections, base station antennas, outdoor installations requiring weatherproof sealing |
| 2.92 mm (K) |
DC – 40 GHz |
Medium |
500+ |
mmWave test and measurement, 5G equipment, precision microwave circuits requiring frequency coverage beyond SMA |
High-Speed Board-to-Board Signal Connectors
High-speed differential signal interfaces — PCIe, USB 3.x, SATA/SAS, 10/25/100G Ethernet — place demanding signal integrity requirements on board-to-board connectors. Impedance control, differential pair routing within the connector body, crosstalk between adjacent pairs, and insertion loss at multi-gigabit frequencies all affect bit error rate. Key manufacturers in this space are Samtec (Edge Rate, FireFly, LSHM), Molex (iPass, SlimStack), TE Connectivity (zSFP+), and Amphenol (FCI Airmax). Always obtain and simulate the connector's S-parameter (Touchstone) file during signal integrity modelling — the connector parasitic effects are often the dominant source of signal impairment in dense high-speed designs.
Connector procurement has four specific considerations that differ from most other electronic component categories, and that consistently generate supply and quality problems when not addressed at the design stage.
🔗Cross-Manufacturer Compatibility — Never Assumed, Always Verified
Connectors that appear physically identical — same pitch, same pin count, same housing dimensions — from different manufacturers or different series within the same manufacturer are frequently not mechanically interchangeable. The mating force, the terminal retention design, the housing latch geometry, and the contact wipe length may all differ in ways that produce a poor or intermittent connection when a non-matched mating half is used. Always test-mate the PCB connector and the harness housing before finalising the design, and specify both the PCB connector part number and the harness connector part number in the bill of materials. Cross-reference compatibility tables published by connector manufacturers for their own series are a starting point, not a substitute for physical testing.
⏳EOL Risk and Alternative Source Preparation
Connector series are discontinued more frequently than most engineers expect, particularly for lower-volume or older-technology types. The impact is disproportionate because both the PCB connector and the mating cable connector must be changed simultaneously — a connector PCB change without a corresponding cable change produces a mismatch. Mitigation at design stage: confirm the selected series' active production status; identify at least one pin-compatible alternative from a different manufacturer; and design the PCB footprint to accommodate both if the footprints are compatible. At procurement: maintain a defined minimum safety stock for connectors used in long-production-run products, and subscribe to manufacturer EOL notification services through your authorised distributor.
🛡️Counterfeit Risk — Real and Documented
Counterfeit connectors from major manufacturers — JST, Molex, TE Connectivity, Amphenol — are present in the market, particularly at prices significantly below authorised distributor levels. Counterfeit connectors typically fail on contact resistance, mating retention force, terminal retention, and high-temperature performance — properties that are not visible on receipt and are not revealed by superficial visual inspection. Mitigation: source from authorised distributors as the default; verify the certificate of conformance includes the manufacturer's name and production lot; conduct contact resistance and retention force measurement on any lot sourced outside authorised channels; and report confirmed counterfeits to ERAI for industry-wide notification.
🔬Sample Evaluation Under Real Application Conditions
Datasheet values are measured under standardised test conditions that may not reflect your application environment. Before finalising connector selection, order samples and validate under your actual conditions: mate and demate the connector the specified mating cycle life and measure contact resistance before and after; apply the actual current load in the housing under your maximum ambient temperature and verify that the housing does not deform or that contacts do not overheat; apply the expected vibration spectrum and verify retention; and assemble the connector in your actual cable assembly process to confirm that the crimp tool and process parameters produce consistently acceptable terminations. Discovering a connector incompatibility during first-article production or field deployment is far more expensive than discovering it on a $200 sample order.
Summary
Electronic connector selection requires evaluating seven criteria simultaneously — electrical specification, mechanical durability, environmental rating, mounting method, physical size, cost and availability, and long-term supply. No single criterion is sufficient on its own, and the most common selection failures result from optimising on one dimension (usually cost or size) while underspecifying the others (usually mating cycle life and long-term availability). The practical approach: start with the connection type to identify the applicable families; specify standard series (JST PH/XH, Molex Micro-Fit, TE MATE-N-LOK) wherever application requirements allow, reserving specialty connectors for requirements that genuinely cannot be met otherwise; verify mating compatibility by physical testing rather than assumption; confirm EOL risk and identify a pin-compatible alternative before design freeze; and conduct sample validation under real application conditions before committing to a production bill of materials. For high-reliability applications — automotive, medical, aerospace — confirm the specific qualification standard (AEC-Q200, ISO 13485, MIL-DTL) on the part number before ordering, not after delivery.