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The "Plastic Leaded Chip Carrier" (PLCC) is a type of surface-mount technology used for integrated circuits. It features leads on all four sides and is typically square in shape. The PLCC was developed to bridge the gap between the dual in-line package (DIP) and the more modern surface mount technologies that became prevalent. It offers a more compact footprint than the older DIPs and is more robust in terms of handling, making it suitable for commercial electronics applications.

A plastic-leaded chip carrier (PLCC) has a rectangular plastic housing. It is a reduced cost evolution of the ceramic leadless chip carrier (CLCC).

A premolded PLCC was originally released in 1976, but did not see much market adoption. Texas Instruments later released a postmolded variant that was soon adopted by most major semiconductor companies. The JEDEC trade group started a task force in 1981 to categorize PLCCs, with the MO-047 standard released in 1984 for square packages and the MO-052 standard released in 1985 for rectangular packages. The PLCC utilizes a "J"-lead with pin spacings of 0.05" (1.27 mm). The metal strip forming the lead is wrapped around and under the edge of the package, resembling the letter J in cross-section. Lead counts range from 20 to 84. PLCC packages can be square or rectangular. Body widths range from 0.35" to 1.15". The PLCC “J” Lead configuration requires less board space versus equivalent gull leaded components, which have flat leads that extend out perpendicularly to the narrow edge of the package. The PLCC is preferred over DIP style chip carriers when lead counts exceed 40 pins due to the PLCC's more efficient use of board surface area.

Here's a detailed overview of PLCC:

Design and Structure

•J-Leaded Pins: The PLCC has "J"-shaped leads on all four sides, which provide both mechanical and electrical connections to the printed circuit board (PCB). The design of the leads allows for surface mounting, and the number can vary, commonly ranging from 20 to 84 leads or more, depending on the complexity of the circuit.

•Plastic Encapsulation: The chip or die inside is encapsulated in a plastic casing, protecting it from environmental factors such as moisture, dust, and mechanical stress.

•Notch or Marking: PLCCs often have a notch or other marking to indicate the proper orientation of the chip, which is crucial during installation to ensure correct functionality.

Installation and Removal

•Sockets: PLCCs are often inserted into sockets rather than being soldered directly onto the PCB. These sockets are soldered to the board, allowing the PLCC to be installed or removed without soldering. This feature is particularly beneficial for chips that may need replacement or upgrading, such as memory devices or micro-controllers.

•Specialized Tools: There are specific PLCC extraction tools designed to remove these chips from their sockets without damaging the chip or socket. The use of a specialized tool is essential, as trying to remove a PLCC with a screwdriver or other makeshift device could lead to damage.

Advantages of PLCC

•Robustness: The PLCC's design is robust, allowing the chips to be handled more roughly than other types of packages without leads. This characteristic is particularly advantageous in manufacturing environments.

•Compact Size: PLCCs offer a more compact solution compared to DIPs, allowing for higher circuit density in devices.

•Upgrade Flexibility: Since PLCCs can be socketed, they offer flexibility for systems that might require upgrades or maintenance. This feature is particularly relevant in scenarios where technology might need to be updated regularly.

Challenges and Considerations

•Heat Dissipation: While PLCCs are compact, this can sometimes lead to issues with heat dissipation, especially in high-performance applications. Additional cooling systems or heat sinks may be required.

•Socket Cost and Reliability: While the use of sockets adds flexibility, it also introduces additional costs and potential points of failure in the connection between the socket and the PCB or the chip and the socket.

•Size Limitations: As technology has advanced, there has been a move towards even smaller package sizes, and PLCCs have, in some applications, been phased out in favor of smaller, more modern packages.

PLCCs are used across various applications, including computers, communication devices, and industrial electronics, particularly during the era when they provided a suitable balance between size, robustness, and ease of handling. However, with advancements in technology, other types of packaging have become more prevalent, especially in highly miniaturized and high-performance applications.