Why IC's have even no of pins?

Answer 1

I would guess its because an even number of IC pins is aesthetically pleasing. Odd numbers of IC pins are certainly possible if you manually cut off a redundant ground pin.

Even in a field such as semiconductor engineering that is apparently removed from the luxury of aesthetics---yielding to maximum packaging efficency---there is still a moderate appeal to make the chip packing aesthetically pleasing because it makes the IC chips appear more organized on the board and easier to count the pin numbers to locate a pin when debugging by counting in 2's. On the other hand, one easily argue for changing the packaging to an odd number of pins so that automation processing equipment can automatically detect the package orientation.

(One could only hope that engineers that work on IC design would have the same philosopy of aesthetics when engineering the internal structures within the IC because the internal structures of an IC design are some of the most messy structures on earth. For example, its often better to sacrifice a little but of space in the name of readability in the IC design code and Extra care needs to be taken to organise the abundance of interconnections between millions of other points in an IC design and to give each signal a name that groups signal bundles together. In contrast the pin names exposed on the outside of the IC are not really so well selected sometime. Especially where there is multiplexing of pin functions, ie. sharing of pin functions of the IC to reuse the pins and save space when the IC is in certain usage mode, thus in this case you might have an odd or even number of virtual pins who's functional changes depending on the IC's shared pins settings. This is all more than you ever wanted to know. )