The form factor is a design aspect that determines the size and shape of computers, housings, devices, boards, modules, plug-in cards, components and connectors. Form factors clarify the size relationship between technically comparable components. Smaller form factors have the advantage over larger ones in that they achieve a higher packing density. More smaller boards or connectors can be accommodated in one housing or connector strip.
- For FO connectors, the form factor is a size ratio of the connector dimensions. This factor is important for connection density in optical distribution systems such as patch panels. There is a special group of small FO connectors called SFF connectors, Small Form Factor.
- For chip packages, the form factor indicates the area ratio between the package size and the chip size. For example, the QFP package has a form factor of approximately 5.5, which means that the size of the package is 5.5 times the size of the chip in the package. In other packages, such as the CSP package, the package area is only about 20% larger than the chip. The form factor is about 1.2.
- In computers, the form factor stands for the size, which is largely determined by the motherboard. Even though laptops characteristically have a clamshell case, there are portable computers with different sizes in the form of notebooks, subnotebooks, ultrabooks, UMPCs, hybrid PCs and netbooks.
- In the case of motherboards, form factors are about the layout format of the motherboard that is matched to the PC case. This format takes into account the location of the individual components, sockets, slots and connectors, and determines which chassis and power supply may be used with which form factor. Drill holes and the power connection are also defined in the form factor. It takes into account runtimes between components as well as heat dissipation. AT), the BAT form factor, the ATX form factor for the extended AT version and the Micro-ATX version, LPX, NLX, the ITX form factor with the smaller variants Mini-ITX, Nano-ITX and Pico-ITX, the DTX form factor and the BTX form factor. The ATX and BTX form factors are standardized by the Formfactors organization. In addition to the form factors for personal computers, there is also a WTX form factor for workstations.
- For power supplies, the form factor specifies the power supply specifications, their dimensions and design guidelines.
- In the case of hard disks, the form factor indicates the diameter of the hard disk in conjunction with its height. Well-known formats include 5.25", 3.5", 2.5", 1.8" and 1.3" hard disk drives and miniature hard disk drives, with these inch specifications corresponding to the form factor. The height of the hard disk drives is also specified as the form factor. For example, there are enclosures that are Half Height, known as Slimline, with a height of 41 mm and Low Profile with 25.4 mm.
- The term form factor is also used for bandpass filters and indicates the selectivity of the filter. This is decisive for how strongly a frequency can be separated from an adjacent frequency. The selectivity is expressed in the slope of the filter. The form factor of filters is defined as the ratio of the bandwidths at attenuations of -6 decibels( dB) to -60 dB.
- Plastic cards are also identified with a format. For example, the ID1 card has a form factor( FF) of 1, which is why it is designated 1FF. The mini SIM card is labeled 2FF, the micro SIM card is 3FF and the nano SIM card is 4FF.