Chip carrier
In electronics, a chip carrier is one of several kinds of surface-mount technology packages for integrated circuits (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.[1]
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 "
Types of chip-carrier package are usually referred to by initialisms and include:
- BCC: Bump chip carrier[2]
- CLCC: Ceramic leadless chip carrier[3]
- Leadless chip carrier (LLCC): Leadless chip carrier, contacts are recessed vertically.[2]
- LCC: Leaded chip carrier[2]
- LCCC: Leaded ceramic chip carrier[2]
- DLCC: Dual lead-less chip carrier (ceramic)[2]
- PLCC:
- PoP: Package on package
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 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.[4]
The PLCC uses 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.[5] 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
A PLCC circuit may either be installed in a PLCC socket or
A specialized tool called a
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", but instead has rounded pins through the edges of the ceramic or molded plastic 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.
See also
References
- ^ ISBN 3-527-29835-5, page 627
- ^ a b c d e f "Integrated Circuit, IC Package Types; SOIC. Surface Mount Device Package". Interfacebus.com. Retrieved 2011-12-15.
- ^ a b "CPU Collection Museum - Chip Package Information". CPU Shack. Retrieved 2011-12-15.
- ISBN 0-412-12921-3.
- ISBN 0-87170-285-1.
- ^ http://www.cpu-world.com/CPUs/80286/Intel-R80286-8.html "Intel R80286-8; Package 68-pin ceramic LCC"