The
Power Quad Flat No Leads
package, or PQFN,
is
a small square-shaped or rectangular surface-mount plastic package with no leads
that is capable of high power dissipation.
Instead of leads, it uses metal pads around the periphery of the bottom
of the package
body for electrical connection to the outside world.
It is basically a 'high-power' version of the quad flat no
leads (QFN) package.
The capability of the PQFN to handle
the heat emitted by high-power devices comes from one or more exposed
heat sinks at the package bottom, as well as its use of thick copper
lead frames, solder die attach material,
and heavy-gauge bonding wires. The heat sinks, which are physically
connected to the die pad, efficiently transfer the excess heat
from the die to the PCB.
Typical PQFN pad counts range from 8 to
42. The maximum package height values of different PQFN
packages vary widely, ranging from 0.9 mm to over 2 mm. The body sizes of typical
PQFN's range from 5 mm.
square to 12 mm. square. The pad pitch
(distance between pads) used by PQFN packages is
usually one of the following: 0.50 mm, 0.65 mm, 0.80 mm, and 0.90 mm.
Table 1. Properties of
Some Examples of PQFN's
|
No. of Pads |
Body
Size |
Package
Height |
Pad Pitch |
|
8 |
3.3 mm x 3.3 mm |
1.1 mm |
0.65 mm |
|
16 |
4 mm x 4 mm |
0.9 mm |
0.65 mm |
|
20 |
5 mm x 6 mm |
0.9 mm |
0.80 mm |
|
24 |
12 mm x 12 mm |
2.2 mm |
0.90 mm |
|
28 |
5 mm x 5 mm |
0.9 mm |
0.50 mm |
|
32 |
4 mm x 6 mm |
0.9 mm |
0.50 mm |
|
32 |
8 mm x 8 mm |
2.2 mm |
0.80 mm |
