| | | | Zero Insertion Force. A type of socket developed for CPU chips to allow processors to be added or removed without the use of special tools and/or large forces. Previously, with the increasing complexity of CPUs and the according increase in number of connecting pins, damage to the chip (or even the circuit board) was becoming more and more likely. With the advent of the PGA (Pin Grid Array) processors, the zero insertion force socket went a long way to resolving this issue. "Ordinary" IC sockets rely on significant friction forces to grip the pins of the chip, making a good electrical contact but also making insertion and extraction without damage difficult. The risk of damage increases as the number of pins does and the force required is multiplied, particularly so in the case of replacing or upgrading CPUs on the home PC where the user may have little or no experience of the task. On a Zero Insertion Force socket, it is immediately apparent that this is a physically larger socket - necessary to allow for the mechanism involved. A lever on the socket is released from it's catch and moved, releasing the tension in the individual pin sockets. The processor is aligned as appropriate then dropped in with "zero insertion force". The lever is then moved back into position - which moves the top plate of the assembly and applies pressure to the individual pin sockets - and then locked in place, creating good electrical contacts and securing the chip in the socket. Outside of the world of Personal Computers, Zero Insertion Force sockets are not commonly used (other than in some testing rigs), due to being relatively expensive and having a large footprint on the printed circuit board. | | | |
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