MTB10N40E

http://onsemi.com

8

RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS

Surface mount board layout is a critical portion of the total

design. The footprint for the semiconductor packages must

be the correct size to ensure proper solder connection

interface between the board and the package. With the

correct pad geometry, the packages will self align when

subjected to a solder reflow process.

mm

inches

0.33

8.38

0.08

2.032

0.04

1.016

0.63

17.02

0.42

10.66

0.12

3.05

0.24

6.096

POWER DISSIPATION FOR A SURFACE MOUNT DEVICE

The power dissipation for a surface mount device is a

function of the drain pad size. These can vary from the

minimum pad size for soldering to a pad size given for

maximum power dissipation. Power dissipation for a surface

from the device junction to ambient, and the operating

The values for the equation are found in the maximum

ratings table on the data sheet. Substituting these values into

50°C/W

= 2.5 Watts

the recommended footprint on a glass epoxy printed circuit

board to achieve a power dissipation of 2.5 Watts. There are

other alternatives to achieving higher power dissipation from

the surface mount packages. One is to increase the area of

the drain pad. By increasing the area of the drain pad, the

power dissipation can be increased. Although one can

almost double the power dissipation with this method, one

will be giving up area on the printed circuit board which can

defeat the purpose of using surface mount technology. For

Figure 16.

Figure 16. Thermal Resistance versus Drain Pad

2.5 Watts

A, AREA (SQUARE INCHES)

Board Material = 0.0625

″

G−10/FR−4, 2 oz Copper

60

70

50

40

30

20

16

14

12

10

8

6

4

2

0

3.5 Watts

5 Watts

Another alternative would be to use a ceramic substrate or

an aluminum core board such as Thermal Clad™. Using a

board material such as Thermal Clad, an aluminum core

board, the power dissipation can be doubled using the same

footprint.