MMDF5N02Z Datasheet, PDF (8/12 Pages) Motorola, Inc – DUAL TMOS POWER MOSFET 5.0 AMPERES 20 VOLTS

MMDF5N02Z
INFORMATION FOR USING THE SO−8 SURFACE MOUNT PACKAGE
MINIMUM 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 inter-
face between the board and the package. With the correct
pad geometry, the packages will self−align when subjected
to a solder reflow process.
0.060
1.52
0.275
7.0
0.155
4.0
0.024
0.6
0.050
1.270
inches
mm
SO−8 POWER DISSIPATION
The power dissipation of the SO−8 is a function of the in-
put pad size. This can vary from the minimum pad size for
soldering to the pad size given for maximum power dissipa-
tion. Power dissipation for a surface mount device is deter-
mined by T_J(max), the maximum rated junction temperature
of the die, R_θJA, the thermal resistance from the device
junction to ambient; and the operating temperature, T_A. Us-
ing the values provided on the data sheet for the SO−8
package, P_D can be calculated as follows:
P_D =
T_J(max) − T_A
R_θJA
The values for the equation are found in the maximum
ratings table on the data sheet. Substituting these values
into the equation for an ambient temperature T_A of 25°C,
one can calculate the power dissipation of the device which
in this case is 2.0 Watts.
P_D = ^{150°C − 25°C} = 2.0 Watts
62.5°C/W
The 62.5°C/W for the SO−8 package assumes the recom-
mended footprint on a glass epoxy printed circuit board to
achieve a power dissipation of 2.0 Watts using the footprint
shown. Another alternative would be to use a ceramic sub-
strate or an aluminum core board such as Thermal Cladt.
Using board material such as Thermal Clad, the power dis-
sipation can be doubled using the same footprint.
SOLDERING PRECAUTIONS
The melting temperature of solder is higher than the rated
temperature of the device. When the entire device is heated
to a high temperature, failure to complete soldering within
a short time could result in device failure. Therefore, the
following items should always be observed in order to
minimize the thermal stress to which the devices are sub-
jected.
• Always preheat the device.
• The delta temperature between the preheat and
soldering should be 100°C or less.*
• When preheating and soldering, the temperature of the
leads and the case must not exceed the maximum
temperature ratings as shown on the data sheet. When
using infrared heating with the reflow soldering
method, the difference shall be a maximum of 10°C.
• The soldering temperature and time shall not exceed
260°C for more than 10 seconds.
• When shifting from preheating to soldering, the
maximum temperature gradient shall be 5°C or less.
• After soldering has been completed, the device should
be allowed to cool naturally for at least three minutes.
Gradual cooling should be used as the use of forced
cooling will increase the temperature gradient and
result in latent failure due to mechanical stress.
• Mechanical stress or shock should not be applied
during cooling.
* Soldering a device without preheating can cause exces-
sive thermal shock and stress which can result in damage to
the device.
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