The
TO-218
is
a
type of plastic-molded "transistor-outline" package that features a flat metal tab at its
back (see Figure 1) to enable it to dissipate relatively large amounts
of heat. The TO-218 is commonly used for housing power
transistors, thyristors, and
integrated
circuits with low lead counts.
The metal tab at the back of the TO-218 serves as a heat sink itself,
but it has a hole so that it can be screwed onto a larger heat sink if
higher power handling capability is required.
A typical TO-218 package has 2 to 5
leads. The lead pitch (distance between leads) of a
TO-218 package varies, depending on the number of leads. For example,
the 5-lead TO-218 package in Figure 1 has a lead pitch of 2.54 mm but an
equivalent 3-lead TO-218 package can have a lead pitch of 5.1 mm.
Table 1.
Properties of Typical TO-218 Packages
|
No. of
Leads |
Body Size
(HxW)
excl.
Metal Tab |
Body Size (HxW)incl.
Metal Tab |
Body Thickness |
Metal Tab
Thickness |
Lead
Pitch |
|
3 |
12.5 mm x 15 mm |
20.5 mm x 15 mm |
4.85 mm |
1.5 mm |
15 mm |
|
5 |
12.5 mm x 15 mm |
20.3 mm x 15 mm |
4.9 mm |
2 mm |
14 mm |
