PCB Connectors

Header Pins

Header pins are simple PCB connectors consisting of rows of metal pins mounted in an insulating housing. They are widely used to connect circuit boards, modules, development boards, displays, sensors, microcontrollers and other electronic assemblies.

What Are Header Pins?

Header pins, commonly called pin headers, are rows of metal contacts arranged at a fixed spacing and held by an insulating plastic housing.

They provide a simple way to electrically and mechanically connect electronic boards and modules. 

       Pin Header

       │ │ │ │ │
       │ │ │ │ │
    ┌──┴─┴─┴─┴─┴──┐
    │  Insulator   │
    └──────────────┘
       │ │ │ │ │
       │ │ │ │ │
       PCB

Where Are Header Pins Used?

  • Microcontroller boards
  • Arduino-compatible boards
  • ESP32 development boards
  • Raspberry Pi accessories
  • LCD modules
  • OLED modules
  • Sensor modules
  • Relay modules
  • Programmer interfaces
  • Debug connectors
  • Jumper connections
  • PCB-to-PCB connections

Male Header Pins

Male headers have exposed metal pins that protrude from the insulating housing.

They are commonly soldered into a PCB and can be inserted into a female header or socket. 

Male Header

   │ │ │ │
   │ │ │ │
 ┌─┴─┴─┴─┴─┐
 │ Housing  │
 └──────────┘

Female Header Pins

Female headers contain socket contacts that accept male header pins. 

Male Pins
   │ │ │
   ▼ ▼ ▼
┌─┬─┬─┬─┐
│ │ │ │ │  Female Header
└─┴─┴─┴─┘

Female headers are commonly used to make modules removable from a main PCB.

Male vs Female Headers

Type Contact Typical Use
Male header Exposed pin PCB connection / jumper connection
Female header Socket Accepts male pins

Single-Row Header

A single-row header contains one line of pins. 

● ● ● ● ● ● ● ●

Single-row headers are commonly used for simple signal connections and module interfaces.

Double-Row Header

A double-row header contains two parallel rows of pins. 

● ● ● ● ● ●
● ● ● ● ● ●

Double-row headers allow more connections in a compact area.

Multi-Row Headers

Headers can contain more than two rows where a larger number of connections is required.

The exact arrangement depends on the connector design and application.

Header Pin Pitch

Pitch is the center-to-center distance between adjacent pins. 

       ← Pitch →
          ●
          │
          │
          ●

Common header pitches include:

  • 2.54 mm
  • 2.00 mm
  • 1.27 mm

Many other pitches are available for specialized applications.

2.54 mm Header Pins

2.54 mm is one of the most common pin-header pitches used in through-hole electronic projects and development boards.

It corresponds to 0.1 inch pitch.

2.00 mm Header Pins

2.00 mm headers are more compact than 2.54 mm headers and are used where space is limited.

1.27 mm Header Pins

1.27 mm headers are used in compact electronic equipment where a high number of connections must fit into a small area.

They require greater care during assembly because the pins are closely spaced.

Through-Hole Header Pins

Through-hole headers have leads that pass through holes in the PCB and are soldered on the opposite side.

They provide strong mechanical attachment and are widely used in development boards and prototypes.

Surface-Mount Headers

Surface-mount headers are soldered directly onto PCB pads without passing through the board.

They are useful when automated PCB assembly and compact construction are required.

Straight Header Pins

Straight headers have pins extending perpendicular to the PCB. 

   │ │ │
   │ │ │
   │ │ │
 ──┴─┴─┴── PCB

They are commonly used for vertical board-to-board and module connections.

Right-Angle Header Pins

Right-angle headers bend the pins approximately 90 degrees. 

     │
     │
─────┘
     │
     │
   PCB

They are useful when the cable or mating connector needs to approach the PCB from the side.

Stackable Header Pins

Stackable headers are designed so that additional connectors can be inserted through or alongside the header.

They are commonly used on development boards and expansion modules.

Breakaway Header Pins

Many pin headers are supplied as long strips that can be separated into the required number of positions. 

● ● ● ● ● ● ● ● ● ● ● ●
        │
        ▼
     Break here
        │
● ● ● ● ●

This makes one long header strip useful for many different PCB designs.

Header Pin Materials

Header pins are normally made from conductive metal and may have a surface plating selected for electrical and mechanical performance.

Common plating materials include tin and gold.

Tin-Plated Header Pins

Tin-plated headers are widely used because they are economical and suitable for many general-purpose PCB connections.

Gold-Plated Header Pins

Gold-plated contacts can provide good corrosion resistance and stable contact performance.

They are often used where connector reliability and repeated mating are important.

Header Pin Insulator

The plastic housing keeps adjacent pins electrically separated and maintains the correct pitch.

The insulation material must be suitable for the operating temperature and electrical requirements of the application.

Header Pin Length

Header pins are available in different lengths.

Important dimensions include:

  • Pin length above the PCB
  • Pin length below the PCB
  • Total pin length
  • Housing height

The correct length depends on the mating connector and PCB configuration.

Pin Header Number of Positions

Headers are available in many different numbers of positions.

Examples include:

  • 1 × 2
  • 1 × 3
  • 1 × 4
  • 1 × 6
  • 1 × 8
  • 1 × 10
  • 2 × 4
  • 2 × 5
  • 2 × 10

Longer headers can normally be cut to the required number of positions when the particular product is designed for this.

Header Pin Numbering

Pin numbering depends on the connector and PCB design.

For a simple single-row header, pins may be numbered sequentially. 

1  2  3  4  5  6
●  ●  ●  ●  ●  ●

For double-row headers, numbering may follow different conventions. Always check the PCB markings or schematic.

Keyed Headers

Some header connector systems include a keying feature that prevents incorrect insertion or orientation.

Keying is especially useful when multiple connectors are physically similar but electrically different.

Polarized Headers

A polarized connector is designed so that the mating connector can only be inserted in the intended orientation.

This helps prevent reversed connections.

Jumper Pins

Header pins are commonly used with jumper caps to configure electronic circuits. 

Pin 1   Pin 2
  ●──────●
   Jumper

Moving or removing the jumper can change the circuit configuration.

Common jumper functions include:

  • Address selection
  • Boot configuration
  • Mode selection
  • Enable / disable functions
  • Hardware configuration

Jumper Cap

A jumper cap is a small removable connector containing conductive contacts that electrically connect adjacent header pins.

The jumper cap is normally installed across two pins.

Header Pins for GPIO

Development boards commonly expose GPIO pins through header connectors. 

Microcontroller
      │
      ▼
┌─────────────┐
│ GPIO Header │
└─────────────┘
  │ │ │ │ │
  ▼ ▼ ▼ ▼ ▼
External Circuit

This makes it easy to connect sensors, displays, relays and other modules.

Header Pins for Power

Headers can also provide power connections.

Typical labels include:

  • VCC
  • 5V
  • 3.3V
  • GND
  • VIN

Always verify the voltage before connecting a module.

Header Pins for Programming

Microcontrollers often use header pins for programming and debugging.

Interfaces can include:

  • UART
  • SPI
  • I2C
  • JTAG
  • SWD

Header Pins for UART

A simple UART header may provide: 

GND
TX
RX
VCC

TX and RX must be connected correctly between two communicating devices. 

Device A TX ─────► Device B RX
Device A RX ◄───── Device B TX
GND ───────────── Device B GND

Header Pins for I2C

An I2C header commonly provides: 

VCC
GND
SDA
SCL

SDA carries data while SCL provides the clock signal.

Header Pins for SPI

An SPI header can contain:

  • VCC
  • GND
  • MOSI
  • MISO
  • SCK
  • CS

The exact number of chip-select lines depends on the application.

Header Pins for Displays

LCD, OLED and other display modules frequently use pin headers.

A simple display interface might contain: 

VCC
GND
SDA
SCL

The actual interface depends on the display module.

Header Pins for Sensors

Sensor modules often expose their electrical connections through a small pin header. 

VCC
GND
Signal
 More complex sensors can provide multiple communication and control signals.

Header Pins for Relay Modules

Relay modules can use header pins for power and control signals. 

 VCC GND IN

The exact voltage and logic requirements depend on the relay module.

Board-to-Board Header Pins

Header connectors can connect two PCBs directly. 

 PCB 1 ████████ │ │ │ │ │ │ ▼ ▼ ▼ ▲ ▲ ▲ │ │ │ ████████ PCB 2

The connector arrangement must provide the correct alignment and mechanical support.

Header Pins and Jumper Wires

Male headers are commonly connected to breadboards and jumper wires.

This is particularly useful during prototyping because circuits can be assembled without permanent soldering.

Header Pins and Breadboards

Development boards with male headers can be inserted into breadboards using jumper wires. 

 Microcontroller │ Header Pins │ ▼ Breadboard │ ▼ Prototype Circuit

Header Pin Current Rating

Header pins have a current-carrying capability that depends on the pin size, contact construction, temperature and manufacturer specifications.

A header should not be treated as an unlimited-current connection just because it is physically large enough for a wire.

For high-current applications, select a connector specifically rated for the required current.

Header Pin Voltage Rating

The voltage rating of a header depends on insulation, spacing, clearance, creepage and the manufacturer's design.

High-voltage applications require connectors specifically rated for the required voltage and applicable safety requirements.

Header Pin Contact Resistance

The electrical contact between a male and female connector has a small resistance.

Dirty, worn or damaged contacts can increase this resistance and cause voltage drop or heating.

Header Pin Corrosion

Environmental moisture and contaminants can cause contact corrosion.

Corroded contacts can produce:

  • Intermittent connections
  • Higher contact resistance
  • Signal problems
  • Voltage drop

Header Pin Mechanical Strength

Through-hole headers generally provide strong mechanical attachment to a PCB because the leads pass through the board.

However, excessive force on a connector can still damage the header, solder joints or PCB pads.

Header Pin Solder Joints

The solder joint connects the metal header pin to the PCB copper pad.

A cracked solder joint can cause intermittent operation. 

 Header Pin │ ▼ ┌───────┐ │ Solder│ └───────┘ │ ▼ PCB Copper Pad

Header Pin Testing

A multimeter can be used for basic continuity testing.

  1. Disconnect power from the circuit.
  2. Identify the pin being tested.
  3. Check continuity from the header pin to the corresponding PCB trace.
  4. Check for shorts to adjacent pins.
  5. Inspect the solder joint.

Testing a Header Pin

Place one multimeter probe on the header pin and the other on the corresponding circuit point.

A low-resistance connection normally indicates continuity.

Be aware that other components connected to the circuit can affect resistance measurements.

Testing for Shorted Header Pins

With the equipment powered off, check adjacent pins for unexpected continuity.

A short can be caused by:

  • Solder bridges
  • Damaged insulation
  • Contamination
  • Incorrect PCB design
  • Damaged connector

Header Pin Troubleshooting

When a module connected through header pins is not working, check:

  1. Connector orientation
  2. Pin numbering
  3. Supply voltage
  4. Ground connection
  5. Signal connections
  6. Solder joints
  7. Loose pins
  8. Damaged female contacts

Loose Header Pin

A loose pin can result from mechanical damage or a cracked solder joint.

The pin may move when the connector is inserted or removed.

Inspect the solder joint and PCB pad before replacing the connector.

Broken Header Pin

A broken pin can interrupt the corresponding electrical connection.

For a simple header, the damaged section can sometimes be replaced by removing and soldering a new header.

Damaged Female Header

Female contacts can lose their spring tension after repeated insertion or mechanical stress.

Possible symptoms include:

  • Intermittent connection
  • Loose mating
  • Signal loss
  • Higher contact resistance

Header Pin Replacement

When replacing a header, match:

  • Number of positions
  • Number of rows
  • Pitch
  • Pin length
  • Pin thickness
  • Mounting type
  • Orientation
  • Insulator height

How to Identify Header Pins

  1. Count the rows.
  2. Count the pins in each row.
  3. Measure the pitch.
  4. Measure the pin length.
  5. Identify straight or right-angle construction.
  6. Determine whether it is male or female.
  7. Check whether it is through-hole or surface-mount.
  8. Inspect the housing dimensions.

How to Select Header Pins

  1. Determine the required number of pins.
  2. Determine the number of rows.
  3. Choose the required pitch.
  4. Choose male or female contacts.
  5. Determine the required pin length.
  6. Choose straight or right-angle orientation.
  7. Check PCB mounting requirements.
  8. Check current requirements.
  9. Check voltage requirements.
  10. Check environmental requirements.

Header Pin Faults

Symptom Possible Cause
No connection Broken pin, cracked solder joint or incorrect mating
Intermittent connection Worn contact, loose pin or corrosion
Module works when moved Loose connector or cracked solder joint
Short between pins Solder bridge or damaged connector
Connector will not mate Wrong pitch, orientation or connector type
Pin bends easily Mechanical damage or excessive force

Advantages of Header Pins

  • Simple construction
  • Low cost
  • Widely available
  • Easy to solder
  • Available in many pitches
  • Available in male and female versions
  • Useful for removable modules
  • Excellent for prototyping

Limitations of Header Pins

  • Basic headers may not be suitable for very high currents.
  • Contacts can wear with repeated mating.
  • Small-pitch headers are more difficult to assemble.
  • Unkeyed headers can be inserted incorrectly.
  • Mechanical stress can damage PCB solder joints.
  • Different headers can look similar while having different dimensions.

Common Header Pin Design Mistakes

  • Using the wrong pitch
  • Reversing the connector orientation
  • Using the wrong pin length
  • Ignoring pin numbering
  • Using an insufficiently rated connector for high current
  • Failing to provide mechanical support
  • Using unkeyed connectors where polarity is important
  • Forcing incompatible connectors together
  • Ignoring PCB footprint dimensions

Key Points

  • Header pins are simple PCB connector systems consisting of rows of contacts.
  • Male headers provide exposed pins while female headers provide sockets.
  • Headers are available in single-row, double-row and multi-row configurations.
  • Pitch is the center-to-center distance between adjacent pins.
  • 2.54 mm is one of the most common header pitches.
  • Headers can be straight, right-angle, through-hole or surface-mount.
  • Breakaway headers can be separated into smaller sections.
  • Header pins are widely used for GPIO, UART, I2C, SPI, power and programming connections.
  • Loose solder joints and worn contacts can cause intermittent connections.
  • Replacement headers must match pitch, position count, rows, orientation and pin dimensions.
  • Always check the pinout and polarity before connecting a module.

Continue Learning About Header Pins

The next pages can cover male headers, female headers, jumper pins, single-row headers, double-row headers, PCB headers, board-to-board connectors, pitch, wiring, testing, troubleshooting, replacement and selection.