ZIF is an acronym for zero insertion force, a concept used in the design of IC sockets, invented to avoid problems caused by applying force upon insertion and extraction.
A normal integrated circuit (IC) socket requires the IC to be pushed into sprung contacts which then grip by friction. For an IC with hundreds of pins, the total insertion force can be very large (tens of newtons), leading to a danger of damage to the device or the PCB. Also even with relatively small pin counts each extraction is fairly awkward and carries a significant risk of bending pins (particularly if the person performing the extraction hasn't had much practice or the board is crowded), as can be seen with the unpopular front-loading mechanism of the Nintendo Entertainment System. Low insertion force (LIF) sockets reduce the issues of insertion and extraction but the lower the insertion force of a conventional socket, the less reliable the connection is likely to be.
With a ZIF socket, before the IC is inserted, a lever or slider on the side of the socket is moved, pushing all the sprung contacts apart so that the IC can be inserted with very little force (generally the weight of the IC itself is sufficient with no external downward force required). The lever is then moved back, allowing the contacts to close and grip the pins of the IC. ZIF sockets are much more expensive than standard IC sockets and also tend to take up a larger board area. Such a technique has disadvantages that the connector will occupy a large volume since it adds the space of the drawbars and the slidable space thereof. Therefore, the technique is not useful in the future development of the chips with a high density and large number of pins. Further, the connecting construction of the patent is not good enough to provide a close engagement between the pins and the drawbars. There are only two engagement points between the pins and the drawbars which will probably result in a poor connection in a short time. Also they are known to bend the IC pins at times. Therefore they are only used when there is a good reason to do so.
Large ZIF sockets are commonly mounted on PC motherboards (from about the mid 1990s forward). These CPU sockets are designed to support a particular range of CPUs, allowing computer retailers and consumers to assemble motherboard/CPU combinations based on individual budget and requirements. CPUs may also be upgraded or replaced during the lifetime of the motherboard socket. Personal computers are among the few applications expensive enough to justify elaborate socket systems. Smaller ZIF sockets are also commonly used in chip-testing and programming equipment.
Patent No. 7,473,120 Issued on Jan. 6, Assigned to Hon Hai Precision for Zero Insertion Force Socket Connector (Chinese Inventors)
Mar 05, 2009; ALEXANDRIA, Va., March 5 -- Jie-Feng Zhang and Qi-Jin Yi, both of ShenZhen, China, have developed a zero insertion force socket...
Patent No. 7,588,453 Issued on Sept. 15, Assigned to Hon Hai Precision for Zero Insertion Force Connector (Taiwanese Inventor)
Sep 18, 2009; ALEXANDRIA, Va., Sept. 18 -- Hao-Yun Ma, Tu-cheng, Taiwan, has developed a zero insertion force connector with an improved...