Introduction
Connecting flexible printed circuits (FPCs) in electronic devices often requires using specialized connectors designed for soft and pliable conductors rather than rigid boards. The two main categories of flexible connectors are FFC (flat flexible cable) and FPC (flexible printed circuit) connectors.
While related, FFC and FPC connectors have distinct characteristics and applications. Understanding the key differences allows selecting the optimal solution for integrating flex circuits into designs.
This guide will examine all aspects of FFC and FPC connectors from materials, design, interfacing, pros and cons, and recommended use cases. By the end, the distinction between connector types and appropriate selection for flex circuit applications will be clear.
FFC Connector Overview
FFC or flat flexible cable connectors are designed to interface with flexible flat cabling. Typical FFC connectors consist of a plastic housing containing a clamping mechanism and set of conductive pads or pins.
Typical FFC Construction
- Flat flexible cable terminated with thin PCB ends
- Insulation carrier material with exposed copper conductors
- Laminated polyester, polyimide, or polyether ether ketone (PEEK)
- ZIF (zero insertion force) style connector mating
- Pitch options from 0.3mm to 1.27mm
FFC cables excel at interconnections over dynamic bending locations between PCBs where a standard wire harness would fail prematurely. The smooth flat shape avoids issues with tangled conductors.
Common applications include disk drive flex cable interconnects, printer carriages, LCD displays, and device hinge connections. The ability to accommodate continuous motion over thousands of cycles with high reliability makes FFCs ideal for these applications.
FFC Connector Styles
While designs vary between manufacturers, FFC connectors come in two primary styles:
Clasp/Latch Type
- Plastic connector housing with metal spring latch
- Latch presses FFC cable into contact pads
- Locking clasp prevents disconnects
- Unlatching enables FFC cable insertion/removal
- Low profile above PCB
Slide-Lock Type
- Housing with movable side locks
- Locks slide forward to press cable into connection
- Reverse sliding releases pressure on cable
- Locks prevent disconnect under vibration
- Provide audible click when engaged
Both styles offer reliable connection for FFC cables under dynamic bending. The latch type focuses on slim form factor while the slide-lock aims for robustness.
FPC Connector Overview
In contrast to FFC connectors, FPC connectors are designed specifically to interface with flexible printed circuit boards rather than raw cable.
Typical FPC Construction:
- Flexible PCB material with conductors on one or both sides
- Polyimide is the most common base material
- Adhesive layer bonds to additional stiffener layers
- Components often attached directly to flex PCB
- Connectors mounted to tail sections
FPCs allow complex flexible circuit boards to be designed with fine features, tight tolerances, and components while still supporting dynamic contours.
Applications such as folding device hinges, concealed / slide-out device interconnects, and wearable or skin-contact electronics benefit from FPC technology. The tailored flexible PCB provides reliability and robustness beyond basic flexible cabling.
FPC Connector Styles
Common connector styles used with FPCs include:
Pressure Actuated Contacts
- Gold plated copper alloy contacts
- Contacts wipe FPC conductive pads
- PCB pivot / lever actuation
- Spring or screw force enables reliable contact
- Wiping action penetrates oxidation
ZIF (Zero Insertion Force)
- Movable side pins align FPC tail
- Cam, hinge, or latch mechanism actuates pins
- Pins pressed into plated through holes
- Enables fingertip mating connection
- Lock prevents vibration disconnect
Well-designed FPC connectors tolerate millions of matings despite presence of vibrations, contaminants, and other challenges.
Key Differences Between FFC and FPC Connectors
While both connecting flexible circuits, FFC and FPC connectors have distinct characteristics making each suited for particular applications.
| Parameter | FFC Connectors | FPC Connectors |
|---|---|---|
| Designed For | Flat flex cables | Flexible PCB tail sections |
| Termination | Exposed conductors | Plated pads and holes |
| Pitch (spacing) | 0.3mm to 1.27mm typical | 0.2mm to 1.5mm typical |
| Current | < 1A typical | Up to 5A depending on pins |
| Actuation Method | Latch, clasp, slide lock | ZIF, pressure contacts |
| Durability | 10,000+ cycles | 100,000+ cycles |
| Resistance | 100+ milliohms | < 50 milliohms |
| Contact Type | Pads or pins | Pins, wiping contacts |
| Alignment | Self-aligning housing | Positive positioning guides |
While overlaps exist, these characteristics help determine optimal selection for a given use case as explored in the next sections.
FFC Connector Applications
The capabilities of FFC cable and connectors make them ideal for:
Dynamic Cables
Continuously flexing interconnects for:
- Disk drive head actuators
- Printer carriages
- Robotics joints
Semi-Rigid Connections
Situations requiring a limited number of flex cycles:
- Hinge connections in laptops
- Concealed compact wiring
- Rapid prototyped connections
Cost-Sensitive Applications
FFCs minimize interconnect costs:
- High density parallel busses
- Consumer electronics
- LED lighting strings
Space Constrained Products
Low profile smooth cable routing where wires won’t fit:
- Foldable devices
- Multi-axis robotic arms
- Automotive wiring
FPC Connector Applications
In contrast, FPC connectors excel in these types of demanding applications:
Maximum Flexibility
FPC material withstands rolling and twisting:
- Medical snake catheters
- Flexible wearables
- Concealed wearable cabling
High Density Circuits
Built-in small components, fine features:
- Glasses / goggles display drivers
- Finger / arm health monitors
- Microfluidics interconnects
Complex Components Integration
Pre-assembled connectors, sensors, ICs:
- Micro-cameras
- Stacked battery contacts
- Multi-chip modules
Rugged Vibration Environments
Gold-plated pins and ZIF actuation withstand shaking:
- Aerospace systems
- Vehicle mounts
- Precision instruments
FFC vs FPC Connector Selection Guidelines
Use these guidelines for selecting the optimal flexible connector:
When to Use FFC Connectors
- Basic cable interconnections with minimal complexity
- Primarily parallel bus type signals or power transmission
- Cost sensitive consumer product applications
- Limited life cycles (under 10,000 flexes)
- Pitch requirements under 1 mm
When to Use FPC Connectors
- Flexible circuit will have integrated components
- Reflow soldering required to attach connectors
- More than 10,000 mating cycles needed
- Conductor spacing under 0.3 mm
- Tight positional accuracy required
- Vibration resistance critical
- Integration with densely packed components
Comparing FFC and FPC Specifications
Connector selection depends heavily on compatibility with physical cable and PCB design constraints.
Key FFC Connector Specifications
- Pitch: Distance between conductor centers
- Cable thickness: Determined by layers and materials
- Contact type: Alloy pads for wiping or soldered pins
- Current rating: Depends on trace size but less than 1 A typical
- Insertion life: 10,000+ cycles typical
- Actuation force: Spring clasp typical around 1 to 5 Newtons
- Alignment precision: +/- 0.5 to 1 mm typical
Key FPC Connector Specifications
- Number of positions: As low as 4 pins up to over 100
- Pitch: 0.2 mm to 2.0 mm options
- Contact type: Copper alloy, gold plated pins
- Current rating: Up to 5A per pin
- Insertion life: 30,000 to 100,000+ cycles
- Actuation force: Ranges from fractions of N to 10 N max
- Alignment precision: +/- 0.1mm achievable
- Withstand voltage: Up to 1500 VAC
Matching physical and performance needs to connector specifications ensures a robust interface between flex circuits.
Pros and Cons Comparison
FFC Connector Pros
- Very low cost
- Ultra slim vertical profile
- High density pin spacing
- Light actuation force
- Good for cost-driven designs
FFC Connector Cons
- Limited cycles vs. FPC connectors
- No integrated component support
- Larger pitch spacing than FPC
- Less ruggedized pin contacts
- Only supports basic flex cable
FPC Connector Pros
- Extreme cycle life rating
- Integrates with flex PCBs
- Supports components and high current
- Tight pitch options to 0.2mm
- Withstands vibration environments
FPC Connector Cons
- More expensive than FFC
- Larger and thicker profile
- Overkill for basic dynamic cabling
- Requires flex PCB for termination
- Longer lead times
New Innovations
Connector technologies continue advancing to meet demanding flexible circuit applications:
- Ultra-fine pitch to 0.1mm enables dense stacking
- Vertical FPC stacking connectors save z-height
- Micro-coax FPC cables for high frequency signals
- Combination rigid-flex compatibility
- Increased ruggedness for wearable deployment
- Chip-scale interconnects under development
- Low-force Nano-connector technology
- Increased cycle life beyond 1 million flexes
Conclusion
FFC and FPC connectors both serve vital roles in interconnecting flexible electronic circuits. While related in broad strokes, details from pitch, lifetimes, termination methods, and integration constraints dictate which approach works best. Engineers must weight tradeoffs between cost, reliability, complexity, and density when selecting connectors to interface with flex cabling and circuits.
Frequently Asked Questions
Q: What is the highest density in terms of pins/positions available for FFC and FPC connectors?
A: The highest density FFC connectors support over 100 positions at 0.3mm pitch. Cutting edge FPC connectors achieve over 200 positions at 0.1mm pitch, although 50-100 positions at 0.5mm pitch is more common.
Q: How are FFC cables and FPC boards fabricated and terminated?
A: FFC cables are typically laminated using adhesive bonding of layers, with conductor exposures laser cut. FPC boards utilize traditional lithographic etching processes allowing tighter tolerances.
Q: Which provides the most compact footprint, FFC or FPC connectors?
A: FFC connectors can achieve extremely thin profiles below 1mm when mated due to the flat flexible cable. FPC connectors inherently require some Z-axis height for the connector housing itself.
Q: What types of signals are supported by FFC and FPC interconnects?
A: FFC and FPC connections support transmission of digital signals, analog signals, power, high-speed differential pairs, RF up to 6 GHz, and more depending on conductor geometry.
Q: What factors determine the lifetime durability of FFC vs FPC connectors?
A: Contact wearing, material fatigue, retention force, and alignment precision are key factors. FPC connectors are engineered for maximum cycles by gold plating, ZIF actuation, and precise guide alignment.
What are FPC and FFC?
The first thing you need to know about the two different types of flexible circuits is what they are. FPC stands for Flexible printed circuit. The other type of flexible circuit is the flexible flat cable. These two types of flexible circuits have a similar structure but differ in cost and manufacturing process. In this article, we’ll discuss both types and how they work. After learning their differences, you can choose the best type for your project.
Flexible printed circuits
Flex circuits are flexible and can bend into the desired shape. They are ideal for small interior spaces, but the production quality is much less stable than for rigid circuits. Flexible circuits consist of thin, film-like materials, including copper foil. Different materials have different shrinkage, and warpage characteristics, so careful design is essential. The following tips will help ensure the highest quality flex circuits.
Flexibility is one of the essential advantages of flexible circuits. Unlike rigid circuit boards, we can manipulate flexible circuits often during assembly, installation, and service. These advantages allow for a high-density device population, lighter conductors, and improved airflow. Flexible circuits will work for you whether your application is small or complex. They are also extremely versatile and can connect various components. An innovative PCB manufacturer designed flexible printed circuits ideal for various applications.
Flexible flat cable
What is a flexible flat cable? A flexible flat cable is an electrical cable made with flat solid conductors. The flexible flat cable is essential for various applications in the electronics industry. Flexible electronics refer to the technology that enables a device to be more flexible. Its unique properties allow it to fit in different places and can be used to power various electronics. Read on to learn more. Here are some examples of a flexible flat cable.
A flat cable’s pitch refers to the spacing between the wire conductors. This distance indicates the pitch. Different cables have different pitches, but common values are 0.5 mm and 1 inch. The pitch of a cable will indicate its ability to accommodate a variety of applications. In addition, the pitch of a cable will affect its flexibility and strength. For example, high-speed ATA interface cables are made with 0.025-inch pitches and have a 0.1-mm pitch.
Pinouts
If you’re trying to connect two computers or other electronic devices, you may wonder which connector to use. FPCs are ideal for straight-through connections, while FFCs are often layered and impedance controlled.
FPC wiring is a flexible circuit board made from a flexible polymer base coated with a protective polymer coating. Because it’s flexible, you can customize the number and spacing of wires. FFC is especially useful for electronics that require a high degree of flexibility. Flexible solar cells, for example, can be made to fit within the spacecraft’s shell. This circuit board is also lightweight compared to the rigid PCB board.
Applications
The similarities between FPCs and FFCs extend to their various applications. For example, both types have copper wires and a thin film of chemically etched copper on one side. They are essential in LCD televisions, printers, cameras, and laptops. In addition, they are ideal in the aerospace industry. However, FPCs are more sophisticated than FFCs. They consist of polyethylene terephthalate (PET), copper wires, and other flexible materials.
Unlike other types of connectors, FPCs have a flat, flexible body with a barrier framework that we can organize after installation. This framework also provides a specific stabilization force. In addition, these connectors are strong and rigid enough to resist shock and vibration. Moreover, they have locking components to lock the connectors. For example, Amphenol makes a vibration-proof FFC and FPC with a 2.49mm pitch.
The Difference Between FPC and FFC?
You may have heard about the terms Flexible flat cable and Flexible circuit. But do you know the difference between these two? How do you know which is better? We’ll explain the differences between these two cables and help you make the right choice for your projects. So, what is the difference between FPC and FFC?
Flexible flat cable
If you’ve ever wondered whether the differences between a flexible flat cable and a traditional round electrical wire are worth the hassle, read on to learn more about the two. Unlike traditional round cables, flexible flat cables are thin and lightweight, making them a popular choice among designers. In addition to helping designers save space, they can add an innovative touch to their designs.
Pitch is the primary difference between a flexible flat and a standard flat cable. Pitch is a measurement of the distance between the centers of two adjacent wire conductors. These cables are often helpful in medical products, industrial automation, pulp and paper, festoon systems, packaging, and semiconductor products. They are also widely used in stereos and scanners, with many other applications. You can find them just about everywhere in modern electronics.
Flexible circuit
In contrast to rigid circuits, flexible circuits can be flexed and maintain their form. They consist of a thin insulating polymer film with a pattern of conductive traces. They have been in use since the Second World War, but their popularity is growing today. There are two main types of flexible circuits: single-sided and double-sided. Single-sided flex circuits have only one metal layer. They add Polyimide or FR4 overlays for added insulation and protection against environmental degradation.
Polymer thick film flex circuits are a subtype of the flexible circuit. We manufacture them by printing the circuit elements onto a thin polymer film. The result is a thin, flexible layer of electrical components. Polymer thick film flex circuits are typically single conductor layer structures, though two or more layers can be printed in a sequence separated by insulating layers. While they are generally less flexible, we can make polymer flex circuits with varying amounts of metal.
Flexible circuit cable
There are many advantages of FFC over FPC for electronic enthusiasts. These cables feature a wide range of capabilities and components. As a result, users often feel confused when choosing which type of cable to use. FFC cables are commonly helpful for high-density electronic applications.
The construction material is the main difference between an FPC and an affixed FFC cable. FPCs are thinner and have thinner conductor layers. FFCs are helpful in LCDs and motherboards. FPCs are made of copper, coverlay, and PI and are customizable in shape and pattern. We can bundle these types of cables together to fit a variety of applications.
Cost
In general, FFC and FCCL cables are similar to each other, but they differ in their cost and applications. We can make these cables with single or double-sided copper wires. They require a chemical etching process and have various layers of coating. The FCCL process produces thicker FFCs. However, some companies use both types of cables for specific projects. When choosing the type of cable to use, consider each material’s application and cost.
Molex offers a line of FFC/FPC connectors. The line of connectors offers a wide variety of profiles, including those with push-style and flip-style actuators. These connectors also come in higher-density versions. A common application for FFC/FPC connectors is in medical equipment. Its versatility allows it to work with different types of cable styles and different circuit sizes.
Connectors
Amphenol offers reliable, flexible, and high-performance connectors for connecting FFC/FPC circuits. The company’s micro flex connectors are available in various sizes and pitches, making them ideal for various industrial applications. Other FFC/FPC connectors available from Amphenol include ClincherTM and DuflexTM, which are excellent for industrial and modulation applications and shock and vibration-prone environments.
In general, FPC cables and connectors cost less than FFC connectors. Companies concerned with costs often choose FFC designs, but they are more practical. The differences between the two are not so noticeable, but they are essential to know. If you’re looking for a high-quality connector, look for one with an internal FPC connector with a 0.3mm pitch.
Summary
You may have heard of Flexible Printed Circuits (FFC), but you might wonder what the difference between them is. These circuits are made from copper and polyimide material and are flexible enough to handle harsh conditions. These circuits are often helpful in LCD televisions, laptops, printers, and other applications where space concerns. There are two types of FPCs: single-sided and double-sided.
One of the main differences between FFC and FPC is how they construct. FFCs have straight-through conductors, while FPCs have multiple traces that can be bent, angled, or tied to a shield. As a result, FPCs are more flexible and are ideal for data cables. FPCs can also have varying pinouts and impedance levels. Depending on the application, you may need to choose an FFC or FPC that works well for your application.
FFCs are thicker than FFCs. They consist of two layers of wire, one insulating foil, and one flat copper conductor. FPCs are helpful in tight spaces and for high-speed applications and are often essential in vehicles. However, they are also more difficult to bend, making them less flexible. So if you’re trying to figure out which connector to use for a particular application, consider FPCs.
Flat Flexible Cables can be helpful in several applications. For example, LCDs and other electronic devices may connect using FFCs. A standard FFC will have one contact on each end, while FFCs with opposite contacts require a connector.
