|
Semiconductor products are manufactured in the form of wafers. These contain a large number of identical circuits. The wafer is then cut up into the individual circuits, these rectangles are called die. The number of die per wafer depends on the following; The type of circuit; e.g. a diode is simple and therefore small, a microprocessor is complex and therefore much larger. The physical size of the wafer; these are typically of 4”, 6”, 8” or 12” in diameter. The process technology used; typically a transistor size is measured in microns(μ). Older CMOS technology will be in the 1μ ~ 2μ range, standard process technology is in the 0.25μ ~ 0.5μ range with the state of the art currently being at 65nm. Silicon wafers are very fragile and easily broken, great care must be taken during storage and transportation. To avoid contamination and degradation silicon should be stored in a controlled inert nitrogen atmosphere. Die are normally put into a package which then makes the circuit easier to handle. There are many type of standard packages available. The type will depend partly on the circuit function and the environment in which it will be used. Typically plastic packages are used in commercial applications and ceramic packages used where more extreme conditions prevail. |
|
Die can be transported using different methods.
· Film This is where the wafer has been cut up and the wafer ‘expanded’ or ‘stretched’ so there is clearance around each die. The die are attached to a normally blue sticky plastic sheet.
· Waffle Tray Each die from the wafer is off loaded into a plastic tray which has individual compartments. The number of die per tray and tray size will obviously vary per circuit.
· Tape & Reel Here each die is put into a consecutive plastic pocket on a strip and covered by a removable film. The strip is then coiled around a standard size reel for easy automatic handling. |
|
For more information about silicon manufacturing and process technology, see :- |
|
Die & Wafer Services |
