The rapid development of modern technology has tightly intertwined our lives with electronics. Embedded systems, communication devices, and consumer electronics all rely on a variety of integrated circuits, playing indispensable roles. To achieve optimal packaging results, a range of packaging types, from BCC to QFP, are widely used. However, despite being overlooked, the PLCC package continues to make remarkable contributions in the field of electronics. If you’re eager to learn more about this type of packaging, this guide will strive to provide you with comprehensive insights!
What is PLCC Package and its Features?
The full form of PLCC is Plastic Leaded Chip Carrier, an uncommon IC packaging used to safeguard sensitive components within an enclosure. Depending on the application, it can have twenty to eighty-four pins or more. Its most distinctive feature is that the pins extend from the bottom of the package at a 90-degree angle and then bend outward, allowing them to be inserted into pin holes of sockets or connectors.
- Compact Structure: Its compact design enhances the spatial efficiency of printed circuit boards, supporting miniaturized or space-constrained devices.
- Pin Configuration: Side-extending pins facilitate the soldering process, offering various connection points to improve signal quality.
- Ease of Handling: Some PLCC components feature chamfered or rounded corners, enhancing both aesthetics and ergonomic handling during assembly and connection.
- Thermal Performance: The PLCC packaging design incorporates thermal considerations, with heat pads on the inner side or exposed metal surfaces for efficient dissipation of generated heat.
- Upgradability: Manufacturers can easily perform the disassembly and replacement of PLCC components, a significant advantage in times of rapid iterative updates.
Construction of PLCC IC Package
- Lead Frame Manufacturing: The manufacturing process of the PLCC chip carrier begins with the creation of the lead frame, which serves as the foundation of the package. Lead frames are typically made from metal alloys like copper. The lead frame features a central die pad where the IC chip is mounted, and leads extend outward. These leads will later be configured for external circuit connections.
- Chip Attachment: In this step, a special epoxy resin is used as an adhesive to bond the chip to the die pad of the lead frame.
- Wire Bonding: As the chip is attached, wire bonding is performed to establish electrical connections between the bonding pads on the chip and the pins of the lead frame. Thin wires made from aluminum or gold are used for wire bonding. Ultrasonic energy is employed by wire bonding machines to connect the wires, ensuring reliable electrical connections.
- Mold Encapsulation: After the wire bonding assembly is complete, it is encapsulated within a plastic mold compound. This compound is a thermosetting resin that provides mechanical protection, environmental conditions, and electrical insulation for the sensitive chip and wire bonds. The molded compound is typically coated around the lead frame and the majority of the area covering the wire bonds and chip.
- Curing and Trimming: The encapsulated assembly enters a curing process where the molded plastic solidifies, forming a protective shell around the IC. Trimming is performed to remove excess molded plastic, exposing the pins and preparing them for the soldering process during circuit board assembly.
- Lead Forming: After trimming, the leads protrude from the plastic leaded chip carrier and are straightened. This can be achieved using automated lead forming instruments to ensure consistent lead structures for precise soldering on the board.
- Marking and Labeling: Packages feature markings or labels displaying important information such as manufacturer logos, part numbers, and orientation indicators. These markings are often laser-etched or ink-printed onto the component surface.
- Tape-and-Reel Packaging: Once PLCC packages pass quality assurance, they are typically packaged in tape-and-reel format. These packages are configured in pockets on a continuous tape, which is wound onto a reel. This packaging layout facilitates efficient automated pick-and-place assembly on circuit boards.
Types of PLCC Package
- PLCC20: A micro-sized PLCC with 20 pins, suitable for various wearable devices and portable electronics, offering extensive functionality in compact spaces.
- PLCC28: A medium-sized package with 28 pins, commonly used across various applications including communication devices and embedded systems.
- PLCC32: Featuring 32 pins, this PLCC package is employed for more intricate circuits and integrated circuits, providing additional pin connections.
- PLCC44: This larger PLCC package with 44 pins is often utilized in applications demanding increased input/output connections.
- PLCC52: With 52 pins, the PLCC52 package caters to high-demand electronic systems, such as those in the communication and computing fields.
- PLCC68: A larger PLCC package, often employed in complex circuits with higher pin and connection requirements.
- PLCC84: Utilized in high-end electronic devices necessitating numerous connections, the PLCC84 package boasts 84 pins. Examples include specific microcontrollers and memory chips.
- PLCC100: A relatively larger PLCC package designed for high-performance applications requiring a multitude of pin connections.
PLCC vs. DIP vs. BGA
|Plastic Leaded Chip Carrier
|Dual In-line Package
|Ball Grid Array
|J-shaped gull-wing or flat leads extending from the sides.
|Two rows of leads extending from the package sides in a linear arrangement.
|Features an array of solder balls on the underside of the package for connection.
|20 to 84
|8 to 64
|64 to 100+
|Moderate space efficiency due to the leaded design.
|Relatively less space efficient compared to modern packages.
|High space efficiency due to compact arrangement of solder balls on the underside.
|Various consumer electronics, automotive, industrial.
|Early computers, consumer electronics, and industrial equipment.
|High-performance computing, networking equipment, graphics cards.
|Exposed leads impart a degree of heat dissipation.
|Through-hole design and lack of exposed leads for effective heat dissipation.
|A large number of solder balls act as an effective heat sink for excellent thermal performance.
PLCC Package Troubleshooting and Repair
- Package Inspection: The initial step involves a thorough visual inspection of the PLCC packaging. Carefully examine the packaging for any signs of damage, such as chips, cracks, or bent leads. Ensure that the packaging is correctly positioned on the board and that the leads are aligned accurately.
- Integrated Circuit Testing: In the event of suspected issues with the PLCC, the integrated circuit should undergo testing. Utilize precise testing equipment like logic analyzers or IC testers to assess the functionality of the ICs. Verify that the IC is performing as intended and producing accurate output signals.
- Verification of Connections: Poor connections can lead to malfunctions in PLCC packages. Inspect the solder joints connecting the PLCC leads to the PCB pads. Employ a magnifying glass or microscope to identify any solder bridges, cold joints, or other 平常PCB soldering defects. Consider reflow soldering to establish proper connections.
- Replacement of Packaging: If the packaging itself is identified as faulty, it may need to be replaced. Safely desolder the defective packaging from the board using a soldering iron or hot air rework station. After removal, prepare the pads for the installation of the new packaging.
- Professional Repair Consideration: Repairing packaging can be intricate and may require specialized tools and expertise. In complex situations, it is advisable to seek the assistance of professionals with experience in repairing ICs. Their expertise can be invaluable for ensuring successful repairs.
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