Key Takeaways (Executive Summary)
- The "Big Three": Molex, TE Connectivity (formerly Tyco/AMP), and JST are the industry standards. Most other brands are compatible "clones" of these designs.
- Pitch is Everything: The most critical spec is "Pitch" (the distance between pins). A 2.54mm connector will not fit a 2.50mm header.
- Connection Style: Know the difference between Wire-to-Board (plugging into a PCB) and Wire-to-Wire(connecting two cables together).
- Locking Mechanisms: For vibration environments, always choose a connector with a Positive Latch (click) rather than just friction.
The Handshake of Your System
The most robust cable in the world is useless if the connector fails. The connector is the "handshake" between your power source, your data, and your device.
In the custom wire harness world, we don't just ask for "a connector." We speak in series and families. While there are thousands of types, 90% of industrial and commercial designs rely on a few proven families from the giants of the industry: Molex, TE, and JST.
Understanding the difference between these types will help you specify a harness that is cheaper to build and easier to source.
Category 1: Wire-to-Board vs. Wire-to-Wire
Before choosing a brand, you must define the function.
Wire-to-Board (Internal)
These connect a harness directly to a Printed Circuit Board (PCB).
- Example: The little white plug connecting a cooling fan to a motherboard.
- Common Series: JST PH, JST XH, Molex KK.
- Characteristics: Usually low profile, smaller pitch, and friction-locked (held in by tightness).
Wire-to-Wire (External/Extension)
These connect two harnesses together (a male plug and a female receptacle).
- Example: The power connector for a car radio or a waterproof extension cable.
- Common Series: Molex Micro-Fit 3.0, TE Mate-N-Lok.
- Characteristics: Larger, rugged, often feature a "click" latch to prevent vibrating loose.
Comparison Table: The "Big Three" Families
These are the most common connectors we see in manufacturing. Use this to identify what you need.
|
Brand & Series |
Pitch (mm) |
Max Current |
Type |
Best Application |
|---|---|---|---|---|
|
JST XH |
2.50 mm |
3A |
Wire-to-Board |
Battery balance leads, 3D printers. |
|
JST PH |
2.00 mm |
2A |
Wire-to-Board |
Small electronics, internal sensors. |
|
Molex Micro-Fit 3.0 |
3.00 mm |
5-8A |
Wire-to-Wire |
Power distribution, compact PCs. |
|
Molex Mini-Fit Jr |
4.20 mm |
9-13A |
Both |
PC Motherboards (ATX), Industrial. |
|
TE Mate-N-Lok |
5.08 mm |
10-15A |
Wire-to-Wire |
Appliances, HVAC, Older automotive. |
|
TE Deutsch DT |
N/A |
13A |
Wire-to-Wire |
Waterproof (IP68) Automotive/Ag. |
The Most Misunderstood Spec: "Pitch"
If you try to plug a JST XH (2.50mm) into a standard Pin Header (2.54mm), it might fit if it's only 2 pins. But if it's 4 pins, it will bend the pins and ruin the board.
Pitch is the exact center-to-center distance between two pins.
- 2.54mm (0.100"): The standard "Breadboard" pitch.
- 2.00mm & 1.25mm: Common for space-saving miniaturization.
- 3.00mm & 4.20mm: Common for power connectors to allow for thicker plastic walls (isolation).
Pro Tip: Never eyeball pitch. Use digital calipers. The difference between 2.50mm and 2.54mm is invisible to the eye but fatal to the connection.
Locking Mechanisms: Friction vs. Positive Latch
How does the connector stay connected?
-
Friction Lock: The plastic housing is molded slightly tight. It stays on by friction alone. (e.g., JST PH).
- Risk: Can vibrate loose over time.
-
Positive Latch: A physical plastic tab that ramps up and "clicks" over a catch. You must squeeze a lever to remove it. (e.g., Molex Mini-Fit).
- Benefit: Vibration proof. Mandatory for automotive and industrial machinery.
Frequently Asked Questions (FAQ)
Q: Can I mate a Molex connector with a TE connector? A: Generally, no. Unless they are specifically built to the same Mil-Spec (like D-Sub connectors), proprietary commercial connectors from different brands do not mate, even if the pitch is the same. The keying (shape of the plastic) will prevent it.
Q: Are "Clone" connectors safe to use? A: Often, yes. Many Asian manufacturers make "compatible" versions of Molex or JST connectors for 50% of the cost. For consumer electronics, these are fine. For aerospace or medical, we stick to the genuine brand to ensure material traceability.
Q: What is a "Keying" feature? A: Keying prevents you from plugging the connector in backwards (reverse polarity). Look for unique shapes (squares vs. arches) on the individual pin housings.
About the Author
Michael Wang
Senior Technical Engineer
As the technical lead at TeleWire, Michael bridges the critical gap between complex engineering requirements and precision manufacturing. With deep expertise in Design for Manufacturing (DFM) and signal integrity, he oversees the technical validation of custom interconnect solutions for mission-critical automotive, industrial, and medical applications.
