MBRB2545CT
3
Rectifier Device Data
INFORMATION FOR USING THE D2PAK SURFACE MOUNT PACKAGE
MINIMUM RECOMMENDED FOOTPRINTS 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.
mm
inches
0.74
18.79
0.065
1.651
0.07
1.78
0.14
3.56
0.330
8.38
0.420
10.66
D2PAK POWER DISSIPATION
The power dissipation of the D2PAK is a function of the drain
pad size. This can vary from the minimum pad size for
soldering to a pad size given for maximum power dissipation.
Power dissipation for a surface mount device is determined by
TJ(max), the maximum rated junction temperature of the die,
RθJA, the thermal resistance from the device junction to
ambient; and the operating temperature, T A. Using the values
provided on the data sheet for the D2P AK package, PD can be
calculated as follows:
PD = TJ(max) – TA
RθJA
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 2.5 watts.
PD = 150°C – 25°C
50°C/W = 2.5 watts
The 50°C/W for the D2PAK package assumes the
recommended drain pad area of 158K mil2 on FR–4 glass
epoxy printed circuit board to achieve a power dissipation of
2.5 watts using the footprint shown. Another alternative is to
use a ceramic substrate or an aluminum core board such as
Thermal Clad. By using an aluminum core board material
such as Thermal Clad, the power dissipation can be doubled
using the same footprint.
GENERAL 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 shall be a maximum of 10°C.
•The soldering temperature and time shall not exceed
260°C for more than 5 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 excessive
thermal shock and stress which can result in damage to the
device.
* Due to shadowing and the inability to set the wave height to
incorporate other surface mount components, the D2PAK is
not recommended for wave soldering.