MMBD1005LT1 Datasheet, PDF (3/8 Pages) Motorola, Inc – Switching Diode

MMBD1005LT1 MMBD2005T1 MMBD3005T1
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
0.037
0.95
0.037
0.95
interface between the board and the package. With the
correct pad geometry, the packages will self align when
subjected to a solder reflow process.
0.037
0.95
0.037
0.95
0.039
1.0
0.098-0.118
2.5-3.0
0.094
2.4
0.031
0.8
inches
mm
SC–59
0.035
0.9
0.079
2.0
0.031
0.8
SOT–23
inches
mm
0.025
0.65
0.025
0.65
0.035
0.9
0.075
1.9
0.028
0.7
SC–70/SOT–323
inches
mm
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉ₀₀ÉÉÉÉÉÉ_..09316ÉÉÉÉÉÉ
1.22
0.048
2.36
0.093
4.19
mm
0.165
inches
SOD–123
POWER DISSIPATION FOR A SURFACE MOUNT DEVICE
The power dissipation for a surface mount device is a
function of the drain/collector 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
mount device is determined by TJ(max), the maximum rated
junction temperature of the die, R_θJA, the thermal resistance
from the device junction to ambient, and the operating
temperature, TA. Using the values provided on the data
sheet, PD can be calculated as follows:
PD =
TJ(max) – TA
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 TA of 25°C, one can
calculate the power dissipation of the device. For example,
for a SOT–23 device, PD is calculated as follows.
PD =
150°C – 25°C
556°C/W
= 225 milliwatts
The 556°C/W for the SOT–23 package assumes the use
of the recommended footprint on a glass epoxy printed circuit
board to achieve a power dissipation of 250 milliwatts. There
are other alternatives to achieving higher power dissipation
from the surface mount packages. One is to increase the
area of the drain/collector pad. By increasing the area of the
drain/collector pad, the power dissipation can be increased.
Although the power dissipation can almost be doubled with
this method, area is taken up on the printed circuit board
which can defeat the purpose of using surface mount
technology.
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.
Motorola Small–Signal Transistors, FETs and Diodes Device Data
3