TO-18
Encyclopedia
In electronics
, TO-18 is a designation for a style of transistor
metal case. The case is made of metal and is therefore more expensive than the similarly sized plastic TO-92 package used for other transistors. The name is from JEDEC
, signifying Transistor Outline Package, Case Style 18.
Different manufacturers have different tolerances, and the actual form factor may vary slightly, depending on function.
There are variants for diode
s, photodiode
s and LED
s that have only two leads; some have parabolic reflectors in the top of the case rather than a sealed, flat top. Diode lasers such as those found in CD players also are often packaged in TO-18 cases, these have the lens also integrated into the case. The flange at the base is also sometimes thicker for the laser packages.
Other types of metal cases containing integrated circuits have as many as eight leads.
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
, TO-18 is a designation for a style of transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
metal case. The case is made of metal and is therefore more expensive than the similarly sized plastic TO-92 package used for other transistors. The name is from JEDEC
JEDEC
The JEDEC Solid State Technology Association, formerly known as the Joint Electron Devices Engineering Council , is an independent semiconductor engineering trade organization and standardization body...
, signifying Transistor Outline Package, Case Style 18.
Construction and orientation
The tab is located 45° from pin 1. The lead diameter is nominally 0.45 mm, and the overall width (not including the tab) is 5.4 mm.Different manufacturers have different tolerances, and the actual form factor may vary slightly, depending on function.
Uses and variants
Generally, the 3-lead TO-18 is used for transistors (which usually have three leads).There are variants for diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...
s, photodiode
Photodiode
A photodiode is a type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation.The common, traditional solar cell used to generateelectric solar power is a large area photodiode....
s and LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
s that have only two leads; some have parabolic reflectors in the top of the case rather than a sealed, flat top. Diode lasers such as those found in CD players also are often packaged in TO-18 cases, these have the lens also integrated into the case. The flange at the base is also sometimes thicker for the laser packages.
Other types of metal cases containing integrated circuits have as many as eight leads.
See also
- Chip carrierChip carrierA chip carrier, also known as a chip container or chip package, is a container for a transistor or an integrated circuit. The carrier usually provides metal leads, or "pins", which are sturdy enough to electrically and mechanically connect the fragile chip to a circuit board. This connection may be...
Chip packaging and package types list - TO-3 a large metal case for power semiconductors