Ribbon cable is a type of flat cable made up of multiple wires running parallel to each other. Commonly used in electronics for internal connections, ribbon cables are especially useful for creating custom cable assemblies using IDC (Insulation Displacement Connector) connectors. This guide explains what ribbon cable is, how it’s used, and how to assemble your own ribbon cable with IDC connectors.
Table of Contents
- What Is a Ribbon Cable?
- Common Types of Ribbon Cable
- Uses of Ribbon Cables and Connectors
- Common Ribbon Cable Sizes and Connectors
- How to Assemble an IDC Ribbon Cable
- Tips for Ribbon Cable Assembly
- Did You Know?
- Frequently Asked Questions (FAQ)
- Conclusion
What Is a Ribbon Cable?
A ribbon cable is a flat, flexible cable made up of multiple conducting wires arranged side by side. The wires are typically color-coded or arranged with a single edge-marking—like a red stripe—to indicate pin 1. Ribbon cables are used for internal wiring in devices such as computers, printers, and microcontroller projects.
Ribbon cables come in different pin counts, such as 10 pin, 16 pin, 20 pin, 26 pin, 40 pin, and 50 pin configurations. These cables can be paired with matching ribbon connectors to create specific interconnects in electronics systems.
Common Types of Ribbon Cable
Here are the main types of ribbon cables used in hobby electronics and computing:
- Flat Ribbon Cable – The classic grey cable with a red edge to mark wire 1.
- Flexible Ribbon Cable – Also called FFC (Flat Flexible Cable), often used in compact electronics like cameras or Raspberry Pi accessories. These are not typically assembled by hobbyists.
- Ribbon Wire – Another term for flat ribbon cable, especially in bulk form.
- Computer Ribbon Cable – Usually refers to legacy internal cables, such as 40-pin IDE cables for hard drives or 34-pin floppy cables.
The following image shows FFC (Flat Flexible Cable) connecting a fingerprint scanner to its controller board.
Uses of Ribbon Cables and Connectors
Ribbon cables are ideal for:
- Connecting peripherals within a device
- Parallel signal transmission
- Custom cable assemblies in prototyping
- Linking PCBs in embedded systems
- Connecting USB programmers to target boards, for example the USB ASP AVR programmer shown below
They are widely used with connectors like:
- IDC Ribbon Cable Connectors (e.g., 10-pin, 16-pin, 20-pin, 26-pin, 40-pin, 50-pin)
- Socket Headers on PCBs
- Pin Headers for prototyping
Common Ribbon Cable Sizes and Connectors
Ribbon cables are available in a wide range of pin counts to suit different applications, from 6-pin to 64-pin or more. Each conductor in the cable corresponds to a pin on the connector, making ribbon cables ideal for parallel data connections.
Standard Ribbon Cable Sizes and Their Applications
| Pin Count | Connector Type | Typical Application |
|---|---|---|
| 6-pin | 6-pin IDC connector | Simple serial interfaces, custom microcontroller connections |
| 10-pin | 10-pin IDC connector | In-system programming (ISP), JTAG, low-pin microcontroller I/O |
| 14-pin | 14-pin IDC connector | Legacy floppy drives, signal headers |
| 16-pin | 16-pin IDC connector | LCD interfaces, general-purpose IO expansion |
| 20-pin | 20-pin IDC connector | Microcontroller interfaces, signal routing |
| 26-pin | 26-pin IDC connector | GPIO headers on embedded platforms |
| 34-pin | 34-pin IDC connector | Legacy floppy disk drives |
| 40-pin | 40-pin IDC connector | IDE hard drives, CD/DVD-ROM drives (legacy computers) |
| 50-pin | 50-pin IDC connector | SCSI-1 interfaces, parallel port extenders |
| 64-pin | 64-pin IDC connector | Custom or industrial data buses |
Note: Ribbon cables with odd pin counts (e.g., 9, 17, etc.) are uncommon, as connectors are standardized around even-numbered contacts.
Legacy vs. Current Use
Ribbon cables were widely used in older computer systems for parallel data transfer — especially in IDE, SCSI, and floppy drive connections. While most modern systems have transitioned to serial interfaces like SATA and USB, ribbon cables are still frequently used in:
- Development boards and embedded systems (e.g., Raspberry Pi, Arduino)
- Industrial automation and custom control systems
- Prototyping and test setups
- LCD and keypad interfaces
- IDC breakout boards
Modern ribbon cables are also found in flat-flex (FFC/FPC) form factors for high-density board-to-board connections, although these cannot be assembled at home and require specialized connectors.
How to Assemble an IDC Ribbon Cable
Making your own IDC ribbon cable assembly is simple with the right parts and tools. Here’s a step-by-step guide.
Parts Required
- Flat ribbon cable (e.g., 20-way)
- IDC connectors (e.g., 20-pin IDC female)
- Optional strain relief clips
Tools Needed
- Scissors
- Bench vice or IDC crimp tool
Assembly Steps
Basic cable assembly steps follow. Also see the images of the assembly steps further down the page.
- Cut the Cable: Trim the ribbon cable to your desired length. Be sure to cut each end at 90 degrees to the length of the cable.
- Identify Pin 1: Look for the red wire and align it with the Pin 1 mark (triangle or arrow) on the connector. The image below shows the triangle highlighted in white. This is normally part of the black plastic and is not that easy to see.
- Insert the Cable: Place the cable between the IDC connector’s body and top clip.
- Crimp the Connector: Press down the clip by hand, then crimp fully using a vice.
- Attach Strain Relief: If included, fold the cable over and snap in the strain relief for added durability.
Repeat the process for the other end if building a two-connector assembly.
Assembly Steps Images
The images below show the steps to make up an IDC cable. This example uses two 20-way (10 pins in 2 rows) IDC connectors. Use the same method for any IDC connector with any number of pins.
Be sure to identify pin 1 on the cable and on the IDC connector. Work out which side of the connector the cable must go into. This depends on your requirements and also if there is a strain relief clip. The cable gets wrapped back over the top of the IDC connector before inserting the clip. Bare this in mind when deciding which side of the IDC connector to push the cable into.
Tips for Ribbon Cable Assembly
- Always double-check cable orientation before crimping.
- Make the cable slightly longer if using strain relief.
- Use a bench vice for even pressure when crimping.
- Don’t force the cable; it should align naturally with the connector’s guide grooves.
Did You Know?
- Ribbon cables were first popularized in the 1950s and became standard in computer hardware.
- The 40-pin ribbon cable was famously used for IDE hard drives and optical drives.
- Flexible ribbon cables (FFCs) are commonly used in modern devices but require specialized equipment to assemble.
- IDC connectors allow rapid cable assembly without stripping wire insulation.
Frequently Asked Questions (FAQ)
What is an IDC ribbon cable?
An IDC ribbon cable is a flat ribbon cable terminated with IDC connectors, which pierce the insulation of the wires to form secure connections without soldering.
Can I make custom ribbon cables?
Yes. Using flat ribbon cable and IDC connectors, hobbyists can create custom cable assemblies for specific applications.
What tools do I need to assemble a ribbon cable?
Basic tools include scissors and a vice or IDC crimp tool. A strain relief clip is optional but recommended.
Are ribbon cables still used in modern electronics?
Yes, though less common in consumer devices, they are still widely used in industrial, embedded, and prototyping applications.
What’s the difference between flat ribbon cable and flexible ribbon cable?
Flat ribbon cable has parallel wires in a flat form and can be hand-assembled. Flexible ribbon cable (FFC) is more delicate and often machine-assembled, used in small form-factor devices. The following image shows an adapter board with FFC cable on the right and multi-colored ribbon cable on the left.
Conclusion
Ribbon cable remains a vital component in electronics, especially for hobbyists, prototypers, and embedded systems developers. Knowing how to assemble an IDC ribbon cable offers flexibility in creating custom cable assemblies for a variety of applications. With the right tools and technique, you can build reliable, neat connections for your electronics projects.
Before working with ribbon cables—especially for custom cable assembly—it’s essential to choose the correct wire gauge for your application. Although ribbon cables typically use 28 AWG conductors, variations exist depending on current requirements and mechanical constraints. For a deeper understanding of wire sizes and how to select the right gauge, check out our Wire Size Chart: How to Choose the Right Gauge.