DAN222
INFORMATION FOR USING THE SOT-416 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 insure 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.
TYPICAL
SOLDERING PATTERN
Unit: mm
0.5 min. (3x)
SOT–416/SC–90 POWER DISSIPATION
The power dissipation of the SOT–416/SC–90 is a
function of the pad size. This can vary from the minimum
pad size for soldering to the pad size given for maximum
power dissipation. Power dissipation for a surface mount
device is determined 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
. Using the values provided on
the data sheet, 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
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
subjected.
•
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 should be a maximum of 10°C.
•
The soldering temperature and time should not exceed
260°C for more than 10 seconds.
•
When shifting from preheating to soldering, the
maximum temperature gradient should 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
excessive thermal shock and stress which can result in
damage to the device.
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0.5 min. (3x)
1.4
0.5
1
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 125 milliwatts.
P
D
=
150°C – 25°C
833°C/W
= 150 milliwatts
The 833°C/W assumes the use of the recommended
footprint on a glass epoxy printed circuit board to achieve a
power dissipation of 150 milliwatts. 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, a higher power dissipation can be
achieved using the same footprint.
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