Integrated circuit
From HvWiki
A mass-produced micro-circuit built into a discrete case, ready for use in other circuits. Etched from a thin wafer of semiconductor material.
Integrated circuits are used in many devices, including microprocessors, audio and video equipment, automobiles and many more.
Integrated circuits are often classified by the number of transistors and other electronic components they contain:
- SSI (small-scale integration): Up to 100 electronic components
- MSI (medium-scale integration): From 100 to 3,000 electronic components
- LSI (large-scale integration): From 3,000 to 100,000 electronic components
- VLSI (very large-scale integration): From 100,000 to 1,000,000 electronic components
- ULSI (ultra large-scale integration): More than 1 million electronic components
Packages and Pin arrangements
Pins are numbered from 1 onwards in a counter-clockwise direction. Starting from the side of the notched or dotted end of the IC for rectangular Dual In-Line (DIL) and Small Outline packages, and next to the tabbed pin for metal can packages (rare today).
Newer chips are Surface Mount Technology (SMD or Small Outline Package (SOP) categorised by small pin pitches from 0.5mm down to 0.02mm and either two or four rows of pins.
Typically, the smaller SMD devices cannot be soldered by hand but must be fixed in place using solder paste and glue, then reflowed using infra red or vapour phase reflow.
Many IC's are static (ESD) sensitive, and as a general rule full antistatic precautions including wrist strap, antistatic mat and earthed soldering iron/workstation should be used at all times.
More modern IC's may be ball grid array (BGA) where solder blobs are used on the underside of the chip with corresponding lands on the PCB. BGA chips are one time use only and cannot be reused or removed easily once installed so it is essential to use the correct reflow equipment and procedures.
