Hallo Raghunathan,

damage caused by electrostatic discharge (ESD) is perhaps the biggest danger for todays electronics. There are so many situations where electrostatic charge is generated, and there are so many people not obeying handling rules, that up to today, the most defects of chips are caused by ESD.
Which voltage is produced if you open a plastik bag? Up to 5000 volt! When you wear a pullover made of some synthetic material, which voltage can be produced when moving your arms? Several thousand volts! Thousands over thousands of volts are produced even with the most 'innocent' handling procedures.

Don't think, that chips must be touched for becoming damaged by electrostatic charge. Even if you only touch package of chip, by carefully trying not to touch any pin, chip can be damaged. Yes, even if you do not touch package at all, chip can be damaged by electrostatic charge. Mechanism is called 'influence'. Electrostatic charge will always be the origin of an electric field. If chip is brought into this electric field, field strength of electric field tries to move charge inside chip. And either by this induced current of by the resulting potential difference inside die, chip can be damaged.

It can often be read in text-books, that electrostatic charge is produced, when TWO isolators are brought into close contact. So, if there's only one isolator there should not be any danger: But that's wrong! Wear-off your pullover made of synthetic material. What will you experience? The effect of extremely high electrostatic charge. Wearing-off pullover generates so much high voltage, that you can even see sparks, when room is dark. To get air conducting you need about 1000V per mm field strength! Estimate the voltage generated....
Human body is no isolator, at all. Between two points of body you will have some tens or hundreds of kOhms, well apart from being an isolator.
Now, think what's happening, when a person presses with thumb heavily on some package of chip, may be, he wants to press it into a socket. Package material is some special epoxy, which is an isolator, of course....

Why do you think, that mounted PCB should not be washed by the help of brushes of synthetic material? Why do you think, that PCB should not by dryed by the help of compressed air? Why do you think, that manufacturers of microelectronic devices put their products into packing by the help of lots of ionized air, allthough devices are completely surrounded by metallic enclosure?

If you carry some chips in an antistatic box, what do you think will happen, if you open the box and put some chips out, before you have discharged the box by the help of earth connection?

Try to imagine, that chips with touchable pins and PCBs with touchable connectors and terminals are something like the open heart of a human body. Whenever you handle chips and PCBs it's like you make an operation at open heart. So, your working place, where you handle these chips and PCBs should look like an operation theatre. Do everything, which is neccessary to keep your 'patient' alive. Only one wrong handling, and your patient is dead or seriously hurted!
Every electronic circuitry needs to have some barrier, like the skin of human body. Everything inside should never be touched or come in contact to things being outside (think also of electrical fields!). Everything outside barrier may be touched.
Barrier could be some grounded cable screen, or some capacitor, varistor or transzorb connected from signal (crossing the barrier) to ground. Everything which prevents high electrostatic charge from penetrating barrier.

By the way, every electronic component is in danger to be damaged by eletrostatic charge or ESD. Not only CMOS, but even discretes!

Bye,
Kai