What is FPC connector

In response to increasing consumer demand for electronics, numerous emerging industries are focusing on developing higher-tech products. However, the need for multifunctional and high-performance characteristics poses a challenge as it requires a large number of circuits and components. This, in turn, results in electronic products that are bulky and heavy, which does not align with the preferences of consumers. To address this issue, flexible circuit board connectors have been developed to provide interconnect solutions that are smaller in centerline or pitch distances, have lower profile heights, and are lightweight.

The full name of FPC connector is Flexible Printed Circuit Connector, specifically designed to facilitate the connection between flexible PCB and other circuit boards or components, ensuring reliable electrical connection and mechanical fixation. FPC connectors play a crucial role in establishing connections among various sections of a flex PCB, enabling the transmission of electrical signals and power. By possessing similar flexibility characteristics as flex PCBs, these connectors can be easily bent and molded into different shapes and angles, making them particularly suitable for applications that demand flexibility and space-saving solutions.

Table of Contents

Components of FPC Connector

FPC connector structure

Plastic Body

The plastic body of the FPC connector contains an evenly spaced structure resembling a fence, which enhances airtightness, connectivity, and terminal protection upon assembly. Care is taken to ensure that the plastic bodies possess adequate strength and toughness, without encountering warping or deformation issues during the SMT process, in accordance with the specific project’s usage requirements.

Plastic body structure of FPC connector

Terminal

The contact end of the flex PCB connector is designed to achieve a higher density arrangement and ensure stable electrical performance. To fulfill these requirements, a narrow contact method is typically employed, utilizing phosphor bronze as the material due to its excellent electrical conductivity and mechanical strength.

Connectors available in the market consist of two terminal structures: blanking terminals and formed terminals. The narrow piece female terminal, which requires sufficient elasticity and a relatively complex shape, poses challenges in the stamping process if formed by traditional methods. Controlling the forming size and precision becomes problematic. Therefore, the female terminal commonly adopts the forming method.

As the FPC connector is intended to be paired with a straight sheet FFC (Flexible Flat Cable), the terminals are classified as female terminals, and thus the blanking method is generally utilized. In the provided illustration, one end of the FPC connector terminal is soldered to the PCB, while the other end is mated with the FPC.

Flexible PCB Connector Terminals

Snap Lock

This component is manufactured from PPS material, known for its exceptional rigidity and seamless integration with the plastic body. Upon inserting the FPC, the locking mechanism is utilized to secure and maintain a specific contact force between the FPC and the connector. The provided figure below illustrates a schematic diagram depicting the mating process between the FPC connector and the flexible PCB.

FPC connector Snap Lock​

Solder Tab

Its purpose is to enhance the connection strength between the connector and the FPC, while preventing potential damage to the terminal-to-FPC solder joints caused by excessive stress. Following assembly, the solder tabs must maintain consistent coplanarity across all terminals. In connectors with a limited number of pins, the inclusion of solder tabs is not obligatory. Commonly used pitch sizes for flex circuit board connectors encompass 0.3mm, 0.5mm, 0.8mm, 1.0mm, 1.25mm, 2.0mm, 2.54mm, 3.96mm, and so forth.

Flex PCB Connector Type

ZIF Connector

Flex Circuits with ZIF Connectors

It refers to the zero insertion force connector. With only one latch, it requires minimal initial insertion force. The primary objective is to facilitate the straightforward insertion and removal of flexible cables or printed circuit boards, thereby preventing component damage caused by excessive force. Consequently, it often serves as the preferred choice for numerous electronic projects and equipment. The key characteristics are as follows:

  • Utilizes a clamping mechanism to securely hold the cable or board in place. The clamping mechanism is engineered to exert minimal force on the inserted component during both insertion and removal processes.
  • Engaging or disengaging the connectors necessitates only low force. This is achieved through the design of the clamping mechanism, which opens or releases the clamping force upon insertion or removal of the cable or PCB board.
  • The clamping force can be adjusted using an actuating device within the ZIF connection, such as a slide or lever. This feature facilitates easy insertion or removal of the cable or board when the actuating mechanism is in the open position. Applying a slight clamping force when the actuating mechanism is closed ensures a stable electrical connection.
  • The contacts on this FPC board connector establish electrical connections with wires, conductive traces, or pins on the board. These contacts are meticulously designed to provide reliable electrical connectivity and maintain excellent signal integrity.

2.54mm Flex Connector

This refers to an electrical connector with a pitch (the distance between consecutive contacts) of 2.54mm, which is designed for the manufacture of flexible PCBA boards. The following are its characteristics:

  • Maintains a uniform pitch of 2.54mm, ensuring compatibility and interchangeability with other connectors that have the same pitch.
  • Multiple contacts are arranged in rows or arrays on the 2.54mm FPC connector, depending on the specific connection design and application requirements.
  • Various termination options are available for connecting the flexible circuit to the connector. Common methods include crimping, soldering, or the use of pressure-sensitive glue, depending on the design and type of flexible circuit.
  • The contacts and the flexible circuit are structurally supported and protected by the connection housing. Typically constructed of plastic or metal, the housing may include components such as alignment guides or keying mechanisms to ensure proper mating and alignment.
  • It is important to consider the current and voltage specifications specified by the manufacturer when selecting the appropriate FPC connector for a given application. The connection must be able to handle the anticipated current and voltage requirements.

High Speed Flex Connector

High-speed flex connectors play a crucial role in supporting high-frequency signal transmission within flexible circuits. These specialized electrical connections are designed to ensure reliable data transfer, minimize signal loss, and maintain signal integrity in applications that require high-speed communication.

  • High-speed flex connectors are often engineered to match the impedance of the transmission lines on the flex circuit, enabling precise impedance control. This impedance matching is particularly important at high frequencies as it helps reduce signal reflections and preserve signal integrity.
  • Differential signaling, where two complementary signals are transmitted through a pair of wires, is commonly used in various high-speed applications. High-speed flex connectors dedicated to differential signaling often incorporate separate ground connections for each signal pair. This design minimizes crosstalk and enhances noise immunity, ensuring robust performance.
  • High-speed flex connectors can provide shielding solutions to reduce electromagnetic interference (EMI) and maintain signal integrity. Shielding helps mitigate signal degradation caused by nearby circuits or external EMI sources. Furthermore, appropriate grounding techniques are employed to ensure reliable signal stability and effective EMI shielding.
  • May utilize controlled impedance contacts, such as controlled impedance pins or pads. These contacts are engineered to maintain a constant impedance connection with the mating connector, thereby reducing signal loss and ensuring accurate signal transmission.

FFC vs FPC Connector

  • FFC, which stands for Flexible Flat Cable, is a compact and lightweight cable. It is characterized by its smaller size and lighter weight compared to FPCs. Additionally, FFCs possess high malleability, allowing them to be bent and twisted without sustaining significant damage. These properties make FFCs suitable for applications with space constraints, such as laptops and mobile devices.
  • FPC, or Flexible Printed Circuit, is a more advanced technology compared to FFCs. It consists of a flexible substrate and a printed circuit board that are laminated together. This unique construction enables FPCs to meet the demands of higher-performance applications. They are commonly employed in industries such as industrial machinery and medical devices, where they can handle a greater number of signals and complex circuitry.
FeatureFFCFPC
ThicknessThinnerThicker
WeightLighterHeavier
FlexibilityMore flexibleLess flexible
ApplicationsSpace-limited applicationsDemanding applications
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