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Terry Yager
May 15th, 2009, 08:30 PM
Category:Hardware
200px|thumb|right|Sockets for 16-pin DIP integrated circuits.
Instead of soldering components directly to a printed circuit board, it?s common to fit ICs using a socket. Use of such sockets simplifies the replacement of ICs by removing the need for soldering equipment that would otherwise be required. Sockets are therefore often used for ICs which are expected at some time to be replaced or upgraded, such as ROMs or CPUs. IC sockets are also used to protect parts from the heat used during soldering ? it is better to melt a cheap IC socket than ruin a possibly rare or expensive chip! Many technicians prefer to install sockets when replacing soldered ICs in order to make subsequent repairs easier. Should future replacement prove necessary, the circuit board need not be exposed to potentially damaging heat generated during desoldering.
However, IC sockets can bring problems of their own. Parts can work themselves loose due to mechanical influences such as shock or vibration. The interface between socket and IC pin is also susceptible to corrosion (oxidation) which can give rise to poor connections. For these reasons, some technicians prefer to solder replacement parts directly to the circuit board. From a manufacturing standpoint, it is also of course cheaper to install components directly on the circuit board, eliminating the extra cost of the sockets themselves. In some cases where there are close-fitting boards or other parts, there may not be enough clearance to allow the use of sockets (i.e. in laptops, etc). Special, so-called 'low-profile' sockets are available which may or not help in such situations. Be sure to check clearance above the chip/socket before installing one.
Another consideration when using sockets is that they are not all created equal. Some sockets have machined holes/pins, while others utilize simple clips to hold the chip in place. The sockets in the picture above are machined. The machined type are considered by many to be better quality, although they usually cost a little more. The machined holes can help to alleviate somewhat the problems outlined above. When the squared-off pins of most chips are seated into the round holes, the corners dig in a little (a type of cold weld), providing a air- and gas-tight fit which is more resistant to corrosion as well as vibration, although still not equal to directly soldering the chip in place.