The main types of electrical connectors are wire connectors, PCB connectors, circular connectors, waterproof connectors, power connectors, data connectors, RF connectors, terminal blocks, and crimp terminals. At Soulin, we usually suggest starting with the job first: is the connector carrying power, signal, data, or RF? Is it going on a PCB, into a cable harness, or into a wet industrial space?
Electrical connectors are small parts, but they can decide whether a product works smoothly or becomes hard to maintain. A good connector keeps current or signals moving cleanly. A poor one may loosen, heat up, corrode, leak, or create faults that are hard to trace later.
We have been making PCB connectors, electrical connectors, wire harnesses, and custom cable assemblies since 2009, so we see connector selection from both the design side and the factory side. In our work, the best connector is not just the one that fits. It also needs the right rating, plating, crimp quality, sealing, tooling, and test plan.
Quick List: Common Types of Electrical Connectors
| Connector Type | Typical Use | Key Selection Points | Related Soulin Product or Guide |
|---|---|---|---|
| Wire-to-wire connectors | Join two wires or cable harnesses | Wire gauge, current rating, lock style, crimp quality, serviceability | Custom wire harnesses / cable assemblies |
| Wire-to-board connectors | Connect wires or cable harnesses to a PCB | Pitch, pin count, current rating, latch design, PCB layout space | PCB connector and cable assembly support |
| Board-to-board connectors | Connect one PCB directly to another PCB | Mating height, alignment, insertion force, board support, current rating | PCB connector selection support |
| Pin headers and female headers | Connect modules, boards, test fixtures, and devices | Pitch, pin count, height, plating, mating cycles, SMT or through-hole type | Pin header connector guide for PCB selection |
| Terminal blocks | Make field wiring easier in panels, control boxes, and power supplies | Wire size, current, voltage, spacing, mounting style, clamp type | Industrial wiring and connector support |
| Crimp terminals | Finish wire ends or connect wires to screws, studs, tabs, or blocks | Terminal shape, wire size, crimp tool, pull force, contact fit | Custom cable assembly and crimping support |
| Circular connectors | Rugged round connectors for sensors, machines, automation, and vehicles | Size, pinout, coding, lock type, IP rating, cable type | M8 connector guide / M12 connector guide |
| Waterproof connectors | Sealed connections for dust, water, oil, washdown, and outdoor use | IP67/IP68/IP69K rating, seal design, cable OD, overmolding, installation | Waterproof circular connector guide / waterproof circular connector series |
| Power connectors | Carry AC or DC power safely | Current, voltage, heat rise, wire size, contact material, safety margin | Power connector and cable assembly support |
| Data connectors | Carry device, board, or network data | Pinout, shielding, signal integrity, cable type, lock style | USB, RJ45, HDMI, SATA, FFC/FPC, and industrial Ethernet connector support |
| RF connectors | Carry high-frequency signals for antennas and communication devices | Impedance, shielding, cable match, frequency range, insertion loss | RF connector and coax cable assembly support |
1. Wire-to-Wire Connectors
Wire-to-wire connectors connect one wire or cable section to another. They are common in automotive wiring, LED lighting, small machines, battery packs, appliances, and control systems. Some are simple crimp connectors, while others use plastic housings, locking tabs, seals, or quick-release designs for easier service.
A typical case is a sensor cable that needs to plug into a machine harness. If the cable may be pulled during maintenance, the connector should not rely only on a loose friction fit. A latch, strain relief, proper terminal match, and pull-force testing can help prevent intermittent faults after repeated service.
Wire-to-wire connectors are also useful when one cable section may need to be replaced without changing the whole system. For example, an outdoor LED cable may need a sealed connector so the installer can replace a damaged section quickly while still protecting the joint from dust and water.
For OEM projects, we can support the full cable side of the connection, including custom wire harnesses and custom cable assemblies. This helps us review the connector, terminal, wire gauge, crimp method, seal design, and inspection plan together before production.
The main details to confirm are wire gauge, current rating, voltage rating, lock style, terminal fit, cable outer diameter, and crimp method. A connector may look correct but still fail if the crimp is weak, the seal does not match the cable, or the housing cannot handle vibration. That is why connector selection should cover the full chain: connector body, contact, cable, seal, crimp, and final inspection.
2. Wire-to-Board Connectors
Wire-to-board connectors connect a cable or wire harness to a PCB. We use this type often in fans, sensors, displays, batteries, motors, smart home devices, industrial controllers, and small electronics.
Think of this connector as the handoff point between outside wiring and the board. The wire side usually uses crimped contacts. The board side may be through-hole or SMT. If the cable will be pulled, moved, or unplugged often, we usually suggest a connector with a latch or lock.
Before a PCB layout is finalized, we always like to check the mating part. Pitch, pin count, current, housing height, orientation, and stock all matter. We explain this in more detail in our PCB pin connector design guide for pinout, pitch, layout, and DFM checks.
3. Board-to-Board Connectors
Board-to-board connectors connect two PCBs directly. No cable is needed. We often see them in devices with a main board and a daughterboard, display board, sensor board, power board, or communication module.
These connectors save space, but they need careful layout. We check mating height, alignment, board support, insertion force, and keepout space. If the boards are not lined up well, the connector can take stress. Over time, that stress may hurt the solder joints or make the connection unstable.
For low-power signals, smaller contacts may be enough. For higher current, we choose stronger contacts and check the datasheet carefully. Our usual rule is simple: match the connector to the real current, voltage, vibration, and use case before locking the layout.
4. Pin Headers and Female Headers
Pin headers are one of the most common PCB connector types we make. They use metal pins held in a plastic base. Female headers are the matching socket side. You will find them in dev boards, embedded devices, industrial boards, test fixtures, telecom equipment, and consumer electronics.
Pin headers can be straight, right-angle, single-row, dual-row, SMT, or through-hole. Common pitches include 2.54 mm, 2.0 mm, and 1.27 mm. When we help customers choose one, we look at pin count, pitch, height, current, plating, and mating cycles.
For PCB projects, our pin header connector guide for PCB selection gives a practical path through footprint review, MOQ, drawing revision, and mating-part availability.
5. Crimp Terminals and Simple Wire Ends
Crimp terminals are used when the end of a wire needs to connect to a screw, stud, tab, block, or another wire. Common types include ring terminals, spade terminals, blade terminals, butt splice connectors, ferrules, bullet connectors, and quick disconnects.
We like ring terminals when the wire must stay fixed under a screw or stud. Spade terminals are easier to remove because the screw does not need to come all the way out. Butt splice connectors join two wires end to end. Ferrules help stranded wire stay clean inside a clamp or terminal block.
Crimping is not just “squeeze it and hope.” We check the tool, die, strip length, wire size, pull force, and contact fit. In our factory quality checks, continuity testing, insulation resistance testing, pull force testing, and mating cycle testing help catch weak connections before they become field problems.
6. Terminal Blocks
Terminal blocks are useful when wires need to land in a control box, power supply, PLC cabinet, HVAC unit, or industrial panel. They make wiring easier to install, label, inspect, and replace.
There are screw terminal blocks, spring clamp types, push-in types, pluggable terminal blocks, and barrier strips. Screw types are familiar and strong when installed correctly. Spring and push-in types are faster for production and service work. Pluggable types are useful when a full module may need to be removed.
When we choose terminal blocks, we look at wire size, current, voltage, spacing, mounting style, and service needs. If the panel will see vibration, heat, or frequent maintenance, the clamp style matters a lot.
7. Circular Connectors
Circular connectors are round connectors used in machines, sensors, automation lines, test equipment, outdoor devices, and vehicles. We use them often because they are easy to seal, easy to key, and easy to lock.
M8 and M12 connectors are two of the most common industrial circular connector types. M8 is smaller and often used for sensors, actuators, compact I/O, and tight spaces. M12 is larger and often used for sensors, IO-Link, industrial Ethernet, fieldbus, and power.
If you are working with small sensor wiring, our M8 connector guide covering codes, pinout, IP ratings, and common uses is a good next read. For automation and industrial wiring, our M12 connector guide for types, pinouts, IP ratings, and selection gives a broader view.
One small detail can save a lot of trouble: check the code. M12 A-code, D-code, X-code, S-code, T-code, L-code, and K-code are not the same thing. We always check coding early because it helps prevent wrong mating, wiring errors, and possible device damage.
8. Waterproof Connectors
Waterproof connectors are used when dust, water, oil, washdown, or outdoor weather can reach the connection. We often support these parts for factory sensors, LED lighting, outdoor equipment, marine systems, agriculture machines, EV-related equipment, and security devices.
IP ratings matter here. IP67, IP68, and IP69K are common, but they do not mean the same thing. Also, the rating may apply only when the connector is properly mated. Cable diameter, seal design, overmolding, panel mounting, and installation all affect real-world sealing.
For this topic, our waterproof circular connector guide comparing IP67, IP68, and IP69K is the most relevant technical link. If you need actual M5, M8, or M12 sealed parts, our waterproof circular connector series for sensors and harsh-environment cable assemblies is the product path to review.
9. Power Connectors
Power connectors carry AC or DC power. This group includes DC barrel connectors, AC plugs, battery connectors, solar connectors, high-current circular connectors, blade connectors, and heavy-duty connector systems.
When we choose power connectors, we focus on current, voltage, heat rise, wire size, contact size, and safety margin. If a connector runs warm in normal use, that is a warning sign. Heat usually means too much resistance, too much current, poor contact, or a bad crimp.
For OEM projects, we also confirm whether the connector or cable assembly needs compliance support. ISO 9001 and IATF 16949 relate to our manufacturing and quality management system. UL may apply to selected certified products or materials, while RoHS and REACH relate to material compliance.
Before production, we help customers confirm which requirement applies to the connector, cable assembly, drawing, material, or finished product. When needed, we can provide the related certificate, material statement, or compliance document for review.
10. Data and Signal Connectors
Data connectors carry information between devices or boards. Common examples include USB, RJ45, HDMI, SATA, FFC/FPC, board sockets, and industrial Ethernet connectors. Signal connectors carry lower-power signals from sensors, switches, encoders, displays, and control modules.
For data and signal connectors, we do not only ask, “Does it fit?” We also check shielding, pinout, contact plating, cable type, and layout. A weak signal connection may not look broken, but it can cause noise, dropouts, or strange errors.
RJ45 is a good example. A basic office RJ45 jack and an industrial Ethernet connector may both be called network connectors, but they are not built for the same place. A factory line may need shielding, stronger locking, and better protection from vibration and dust.
11. RF Connectors
RF connectors are used for high-frequency signals. Common types include SMA, SMB, BNC, MCX, N-type, and U.FL. They are used in antennas, wireless modules, test equipment, GPS devices, radios, and communication gear.
RF connectors care a lot about impedance, shielding, and cable match. A bad RF connection may not fail like a power connector. Instead, it may reduce range, add noise, or create signal loss. So we always choose the connector and cable together.
How to Choose the Right Electrical Connector
The right connector depends on the job it needs to do, the environment it will work in, and the way it will be assembled and tested. Use the checklist below before locking the connector type, PCB layout, or cable design.
| Selection Factor | What to Confirm | Why It Matters |
|---|---|---|
| Application | Power, signal, data, RF, board-to-board, wire-to-board, or wire-to-wire | Different applications need different contact designs, shielding, locking styles, and current capacity. |
| Current and voltage | Rated current, rated voltage, safety margin, and heat rise | A connector that is underrated may overheat, loosen, or fail during long-term use. |
| Pin count and pitch | Number of circuits, PCB pitch, housing size, and layout space | These details affect PCB footprint, mating part availability, and assembly accuracy. |
| Wire gauge and cable OD | Wire size, insulation diameter, cable outer diameter, and strain relief | The connector, terminal, seal, and crimp tool must match the actual cable. |
| Environment | Indoor, outdoor, wet area, oil exposure, dust, vibration, or vehicle use | Harsh environments may require waterproof connectors, stronger locks, sealing, or vibration-resistant designs. |
| IP rating | IP67, IP68, IP69K, or no sealing requirement | Waterproof performance depends on the connector, cable fit, seal design, and correct mating. |
| Mating cycles | One-time assembly, occasional service, or frequent plugging and unplugging | Higher mating cycles may require better plating, stronger contacts, and more durable housings. |
| Compliance | UL, RoHS, REACH, IATF 16949, ISO 9001, or project-specific requirements | Compliance needs should be confirmed early, especially for automotive, industrial, and export projects. |
| Samples and testing | Samples, drawing review, continuity test, insulation test, pull force test, and sealing test | Testing helps catch weak crimps, wrong mating parts, poor sealing, or unstable connections before mass production. |
For PCB connector projects, confirm the footprint, height, orientation, and mating direction before the layout is finalized. For cable connector projects, confirm the terminal, crimp method, cable OD, strain relief, and locking style before tooling or production begins.
At Soulin, connector selection is not only about finding a part that fits. Our production process includes mold development, stamping, injection molding, automated assembly, and vision inspection, so we help customers review the connector, cable, drawing, sample, and test plan together before problems reach production.
Common Mistakes We Help Customers Avoid
Some connector problems start with parts that look similar but are not actually interchangeable. For example, two M8 or M12 connectors may have the same size but different coding, pinouts, locking styles, current ratings, or sealing designs. The same problem can happen with PCB headers when the pitch, mating height, plating, or footprint is slightly different.
The cable side also needs to be checked early. A waterproof connector can still leak if the cable outer diameter does not match the seal. A crimp connector can pass a quick visual check but fail later if the terminal, wire gauge, strip length, or crimp tool is wrong. A PCB connector may fit the board but become unstable if the footprint, board support, or insertion force is not reviewed before layout release.
Testing is the final step that catches many hidden issues before production. For standard cable or connector assemblies, we usually check continuity, insulation, mating fit, and pull strength. For harsher applications, heat, humidity, vibration, shock, sealing, and mating-cycle tests may also be needed. These checks take time, but they are much cheaper than finding a weak connector after the product ships.
FAQs
If you are selecting a connector for a new product, replacing an existing part, or building a custom cable solution, we can help with connector selection support before production starts.
