Silicon chips are too small to be connected by ordinary wire, however fine it is. Instead, minute “tracks” of a conducting material such as copper are printed on the circuit board to link the silicon chips.
Open up a television or a radio and you’ll see it’s built around a printed circuit board (PCB): a bit like an electric street-map with small electronic components (such as resistors and capacitors) in place of the buildings and printed copper connections linking them together like miniature metal streets. Circuit boards are fine in small appliances like this, but if you try to use the same technique to build a complex electronic machine, such as a computer, you quickly hit a snag. Even the simplest computer needs eight electronic switches to store a single byte (character) of information. So if you want to build a computer with just enough memory to store this paragraph, you’re looking at about 750 characters times 8 or about 6000 switches—for a single paragraph! If you plump for switches like they had in the ENIAC—vacuum tubes about the size of an adult thumb—you soon end up with a whopping great big, power-hungry machine that needs its own mini electricity plant to keep it running.
Integrated circuits changed all that. The basic idea was to take a complete circuit, with all its many components and the connections between them, and recreate the whole thing in microscopically tiny form on the surface of a piece of silicon. It was an amazingly clever idea and it’s made possible all kinds of “microelectronic” gadgets we now take for granted, from digital watches and pocket calculators to Moon-landing rockets and missiles with built-in satellite navigation.
Integrated circuits fit into printed circuit boards (PCBs) like the green one you can see here. Notice the thin tracks linking the “legs” (terminals) of two different ICs together. Other tracks link the ICs to conventional electronic components such as resistors and capacitors. You can think of the tracks as “streets” making paths between “buildings” where useful things are done (the components themselves). There’s also a miniaturized version of a circuit board inside an integrated circuit: the tracks are created in microscopic form on the surface of a silicon wafer.
Picture Credit : Google