Description       

IC sockets and headers are board-mounted, female connectors that serve as carriers for integrated circuit (IC) chips. They are made of metal or plastic and contain one or more rows of contacts, conductive elements that mate with corresponding elements to provide an electrical path. Many types of IC sockets and headers are available.

Solderless sockets are compression-mounted devices that sometimes lock into place with a bolt or screw. By contrast, zero insertion force (ZIF) sockets use a cinching lever. For more permanent connections, IC sockets and headers are mounted with either surface mount technology (SMT) or through hole technology (THT). SMT adds components to a printed circuit board (PCB) by soldering component leads or terminals to the top surface of the board. By contrast, through hole technology (THT) mounts components by inserting leads through holes in the board and then soldering the leads in place on the opposite side of the board.  

Performance Specifications

  
Performance specifications for IC sockets and headers include voltage rating, current rating, insulation resistance, contact resistance, dielectric withstanding voltage, and operating temperature. Voltage rating and current rating are maximum values. Insulation resistance measures the electrical resistance between two conductors that are separated by an insulating material. Contact resistance measures the electrical resistance of mated contacts when assembled for typical service. Overall contact resistance is a wire-to-wire measurement. Dielectric withstanding voltage, another important specification for IC sockets and headers, is the maximum potential gradient that a dielectric material can withstand without failure. Dielectric strength depends upon the thickness of the material and the method and conditions of the test.    
  

Chip Packaging

There are a variety of IC packages for IC sockets and headers. Examples include ball grid array (BGA), chip scale package (CSP), single in-line package (SIP), dual in-line package (DIP), plastic leaded chip carrier (PLCC), small outline integrated circuit (SOIC), and transistor outline (TO). BGA places output pins in a solder ball matrix and offers reduced package size and improved heat dissipation. Related packages include land grid array (LGA), pin grid array (PGA), and interstitial package grid array (IPGA). CSP devices are no more than 20% larger than the built-in die. QFP devices contain a large number of fine, flexible, gull winged shaped leads. Package types for IC sockets and headers also include single in-line memory module (SIMM), dual in-line memory module (DIMM), and small outline dual in-line memory module (SO-DIMM). Test sockets, display sockets, and receptacles are commonly available.

Standards

• A-A-55162 - CONNECTORS, ELECTRICAL, SOCKETS SINGLE IN LINE MEMORY MODULE, SINGLE AND DUAL VERTICAL TYPE, 30 OR 60 CONTACTS
• BS EN 60603-12 - CONNECTORS FOR FREQUENCIES BELOW 3 MHZ FOR USE WITH PRINTED BOARDS - PART 12. DETAIL SPECIFICATION FOR DIMENSIONS, GENERAL REQUIREMENTS AND TESTS FOR A RANGE OF SOCKETS DESIGNED FOR USE WITH INTEGRATED CIRCUITS
• BS 6493 P2 S2.3 - SEMICONDUCTOR DEVICES - PART 2. INTEGRATED CIRCUITS - SECTION 2.3 RECOMMENDATIONS FOR ANALOGUE INTEGRATED CIRCUIT

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