How to Properly Crimp Connectors for Reliable Connections

When it comes to building electronic circuits or wiring up hardware, one simple but essential process can make the difference between long-term reliability and frustrating failures: crimping connectors.

Crimping is the act of compressing a metal terminal around a wire using a special tool to form a secure electrical and mechanical connection. It might seem like a minor step, but improper crimping can lead to weak connections, intermittent faults, or even complete system failure especially in environments with vibration, heat, or movement.

In this blog, we’ll take you through the basics of crimping, explore the common connector types, and provide a step-by-step guide to help you achieve perfect crimps every time.

Why Crimping Matters

A crimped connection, when done correctly, creates a cold weld between the wire and terminal, ensuring:

• Low resistance electrical connection
  

• Strong mechanical grip
  

• Corrosion resistance (when insulated or sealed)
  

• Consistency in automated or mass production systems
  

Unlike soldering, crimping doesn’t require heat, and in many professional setups, it's the preferred method for wire termination especially in automotive, aerospace, and industrial environments.

Common Connector Types That Use Crimping

You’ll encounter crimping in a wide variety of connectors. Here are some of the most popular:

1. Dupont Connectors

• Used in jumper wires for breadboards and development boards.
  

• Comes in male and female housings.
  

• Requires small pin crimp terminals.
  

2. JST Connectors

• Widely used in battery packs, servos, and embedded devices.
  

• Known for compact size and locking mechanism.
  

• Available in variants like JST-XH, JST-SH, and JST-PH.
  

3. Molex Connectors

• Common in power and signal wiring for PCBs.
  

• Provides a solid, click-fit connection for both data and power.
  

4. Automotive Spade/Blade Terminals

• Used for high-current applications like relays, motors, or car electronics.
  

• Crimped using wider-jaw tools.
  

5. Ferrules

• Crimped onto stranded wires to prevent fraying and ensure solid insertion into terminal blocks.
  

Tools You’ll Need

Before we get started, here’s what you’ll need in your crimping toolkit:

✅ 1. Crimping Tool (Crimper)

Choose one based on the terminal type. For example:

• Dupont/JST crimpers: SN-28B or Engineer PA-09
  

• Automotive terminals: Ratcheting crimpers with interchangeable dies
  

• Ferrules: Square or hexagonal ferrule crimpers
  

✅ 2. Wire Strippers

Used to cleanly strip the insulation off wires without nicking the strands.

✅ 3. Quality Terminals and Housings

Using cheap or incompatible terminals can lead to poor results.

✅ 4. Multimeter (Optional)

To test for continuity and resistance after crimping.

Step-by-Step: How to Crimp Like a Pro

🔹 Step 1: Select the Correct Terminal and Wire Size

Make sure your wire gauge (AWG) matches the terminal specification. For example:

• Dupont pins: typically 22–28 AWG
  

• JST-XH: 22–26 AWG
  

Too large a wire won’t fit in the terminal; too small will result in a loose crimp.

🔹 Step 2: Strip the Wire

• Use a wire stripper to remove 2–3 mm of insulation.
  

• Do not damage or cut any of the copper strands.
  

• Twist the strands lightly to keep them together.

🔹 Step 3: Insert the Wire into the Terminal

Inspect your terminal:

• The inner wings (smaller set) should wrap around the wire strands.
  

• The outer wings (larger set) will grip the insulation.
  

Slide the wire in so that:

• The bare copper reaches the crimp area.
  

• The insulation sits just before the second set of wings.
  

🔹 Step 4: Insert into the Crimp Tool

• Place the terminal into the matching die of the crimp tool.
  

• Ensure the open wings face inward and the correct part of the terminal is aligned.
  

• Gently squeeze to pre-grip the terminal in place if your tool allows.
  

🔹 Step 5: Crimp!

• Squeeze the tool fully until it ratchets and releases (if using a ratcheting tool).
  

• If using a manual tool, apply steady pressure without crushing or over-tightening.
  

• Remove and inspect the crimped joint.
  

A good crimp should:

• Hold the wire securely try tugging it gently.
  

• Show tight contact without crushing or folding.
  

• Have the wings neatly wrapped not splayed or flattened.
  

🔹 Step 6: (Optional) Insert into Connector Housing

If you’re using a connector housing:

• Match the terminal’s side with the locking latch.
  

• Push it in until you hear or feel a click.
  

• Tug lightly to ensure it’s locked in place.
  

Pro tip: Insert all terminals in the correct pin order according to your wiring plan or schematic.

Testing and Verifying Crimp Quality

After crimping, don’t forget to test:

• Continuity using a multimeter
  

• Pull strength by gently tugging the wire
  

• Visual inspection under good lighting or magnification
  

For mission-critical connections (e.g., drones, automotive), consider:

• Adding heat shrink tubing for extra strain relief
  

• Using weatherproof connectors in harsh environments
  

Common Crimping Mistakes to Avoid

Here are a few things to watch out for:

Remember, a bad crimp may pass at first but fail after some vibration, current, or time so always take your time and do it right.

Where to Get High-Quality Crimping Tools & Connectors

If you’re looking to get started with crimping or upgrade your toolkit, here are some essentials to look for (links can be inserted once provided):

• Dupont and JST connector kits
  

• SN-28B or PA-09 crimping tool
  

• Ferrule sets with crimper
  

• Molex housing and pins
  

• Wire stripper + cutter combo tool
  

Having the right tools makes all the difference between frustration and smooth wiring sessions.

Real-World Applications

Crimp connectors are everywhere:

• Arduino and Raspberry Pi projects using jumper wires and sensor modules
  

• Drones and RC cars using JST/Molex for motors and battery connections
  

• Prototyping and robotics where fast and swappable connections are a must
  

• Automotive mods and repairs, where reliability is critical
  

Mastering crimping means you can customize your wiring, reduce clutter, and improve overall system dependability.

Final Thoughts

Crimping might seem like a small detail in a large project but like any great engineering, reliability is built from the ground up. Taking the time to learn proper crimping technique will save you from hours of future debugging and bring a more professional finish to your DIY electronics builds.

So next time you’re wiring up a project, skip the tape, skip the twist-and-hold. Reach for your crimp tool and make that connection count.