electronics Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield ...

, a chip carrier is one of several kinds of

surface-mount technology Surface-mount technology (SMT), originally called planar mounting, is a method in which the electrical components are mounted directly onto the surface of a printed circuit board (PCB). An electrical component mounted in this manner is referred ...

packages for

integrated circuit An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...

s (commonly called "chips"). Connections are made on all four edges of a square package; compared to the internal cavity for mounting the integrated circuit, the package overall size is large.Kenneth Jackson, Wolfgang Schroter, (ed), ''Handbook of Semiconductor Technology Volume 2'', Wiley VCH, 2000, , page 627

Types

Chip carriers may have either J-shaped metal leads for connections by solder or by a socket, or may be lead-less with metal pads for connections. If the leads extend beyond the package, the preferred description is " flat pack". Chip carriers can be smaller than

dual in-line package In microelectronics, a dual in-line package (DIP or DIL) is an Semiconductor package, electronic component package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole technology, throu ...

s and since they use all four edges of the package they can have a larger pin count. Chip carriers may be made of ceramic or plastic. Some forms of chip carrier package are standardized in dimensions and registered with trade industry associations such as

JEDEC The Joint Electron Device Engineering Council (JEDEC) Solid State Technology Association is a consortium of the semiconductor industry headquartered in Arlington County, Virginia, Arlington, United States. It has over 300 members and is focused ...

. Other forms are proprietary to one or two manufacturers. Sometimes the term "chip carrier" is used to refer generically to any package for an integrated circuit. Types of chip-carrier package are usually referred to by initialisms and include: * BCC: Bump chip carrier * CLCC: Ceramic leadless chip carrier * Leadless chip carrier (LLCC): Leadless chip carrier, contacts are recessed vertically. * LCC: Leaded chip carrier * LCCC: Leaded ceramic chip carrier * DLCC: Dual lead-less chip carrier (ceramic) * PLCC: Plastic leaded chip carrier * PoP:

Package on package Package on a package (PoP) is an integrated circuit packaging method to vertically combine ball grid array (BGA) packages for discrete logic and Semiconductor memory, memory. Two or more packages are installed atop each other, i.e. stacked, with a ...

Plastic-leaded chip carrier

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

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 uses a "J"-

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

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. The heatspreader versions are identical in form factor to the standard non-heatspreader versions. Both versions are JEDEC compliant in all respects. The heatspreader versions give the system designer greater latitude in thermally-enhanced board level and/or system design. RoHS compliant, lead-free and green material sets are now qualified standards. Tool used to extract leaded chip carriers from sockets

Tool used to extract leaded chip carriers from sockets

A PLCC circuit may either be installed in a PLCC socket or surface-mounted. PLCC sockets may in turn be surface mounted, or use

through-hole technology In electronics, through-hole technology (also spelled "thru-hole") is a manufacturing scheme in which leads on the components are inserted through holes drilled in printed circuit boards (PCB) and soldered to pads on the opposite side, eithe ...

. The motivation for a surface-mount PLCC socket would be when working with devices that cannot withstand the heat involved during the

reflow Reflow soldering is a process in which a solder paste (a sticky mixture of powdered solder and flux (metallurgy), flux) is used to temporarily attach anywhere from one to thousands of tiny electrical components to their contact pads, after wh ...

process, or to allow for component replacement without reworking. Using a PLCC socket may be necessary in situations where the device requires stand-alone programming, such as some

flash memory Flash memory is an Integrated circuit, electronic Non-volatile memory, non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for t ...

devices. Some through-hole sockets are designed for prototyping with

wire wrap Close-up of a wire-wrap connection Typical wire wrap construction of crossbar_switch.html" ;"title="Bell System telephone crossbar switch">Bell System telephone crossbar switch. Some types of connection were soldered. Wire wrap is an electron ...

ping. A specialized tool called a PLCC extractor facilitates the removal of a PLCC from a socket. PLCCs continue to be used for a wide variety of device types, which would include memory, processors, controllers, ASICs, DSPs, etc. It is particularly common for read-only memories, as it provides an easily swappable socketed chip. Applications range from consumer products through automotive and aerospace.

Leadless

A leadless chip carrier (LCC) has no "

leads Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

", but instead has rounded pins through the edges of the

ceramic A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcela ...

or molded

plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...

package. Prototypes and devices intended for extended temperature environments are typically packaged in ceramic, while high-volume products for consumer and commercial markets are typically packaged in plastic.

References

{{Semiconductor packages

Types

Plastic-leaded chip carrier

Leadless

See also

References