CMOS devices can be damaged by voltages as low as 250V, so the first precaution to observe is to ensure that the handler is not carrying a static charge. An operative handling such devices in the course of their daily work may have an earthed mat on the bench and an earthed wrist strap to allow any charge to leak away, but for the amateur constructor such extreme precautions are really unnecessary. It is however wise to earth one's body momentarily before handling a CMOS IC and this can be done by touching the metal casing of any earthed electrical appliance which is plugged in but not switched on e.g. a cold soldering iron.
CMOS ICs are supplied in some form of conductive packing, which may be simply aluminium foil, or black (carbon filled) plastic foam. Shielding bags are sometimes used, but the plastic tubes marked ANTISTATIC are not very effective and ICs in these should be handled with extra care. A sensible way to ensure that devices are not damaged is to use IC holders and to insert the devices only when construction is complete and the layout has been checked. Plastic insertion and removal tools are not expensive and are preferable to fingers for manipulating the devices. No device should be inserted while power is applied to the Circuits and obviously one should make sure that the device is inserted the right way round.
Brian Marshall has provided a list of components and the voltages which can damage them, and also some details about protecting such devices:
Device Type Minimum damaging voltage VMOS 30 MOSFET 100 EPROM 100 JFET 140 Op-amp 190 CMOS 250 Schottky diodes 300 Film resistors 300 Bipolar transistors 380 SCRs 680 Schottky TTL 1000Most CMOS ICs are equipped with internal protective diodes which limit voltages at the inputs to a safe level, but care is still advisable in handling them. If they have to be soldered in directly, the VDD pin should be connected before any earth connection is made.
Some beginners are anxious about the possibility of component damage during soldering operations. It is true that some components are affected by heat, for instance, resistors change their value when heated, and extreme heat can damage Semiconductors such as diodes and transistors. The best way to avoid such damage is to acquire sound soldering technique. If the surfaces being soldered are clean, the soldering iron need only be applied to the joint for a short time, and the temperature rise in the body of the component will be too small to cause any damage. One can buy soldering stunts to clip on transistor or other leads during soldering operations, but they are really unnecessary - a pair of flat nosed pliers can be applied where one needs to avoid heat being conducted to a sensitive device.