MMBVI05GLTI
INFORMATION FOR USING THE SOT-23 SURFACE MOUNT PACKAGE
MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS
@Surface mount board layout is acritical portion of the total intetiace between the board and the package. With the
design. The footprint for the semiconductor packages must correct pad geometry, the packages will self align when
be the correct size to insure proper solder connection subjected to asolder reflow process.
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SOT-23 POWER DISSli
The power dissipation of the SOT–23 is afunction of the ,?s’~$; SOLDERING PRECAUTIONS
pad size. This can vary from the minimum pad size for f“’”’”>?; ‘s
+./The melting temperature of solder is higher than the rated
,B,.’*,
soldering to a pad size given for maximum power dissipation., y:i +
~+u.~!,temperature of the device. When the entire device is heated
Power dissipation for asurface mount device is determined’~+$~,
a
by TJ(m=), the maximum rated junction temperatur~}of t~ to ahigh temperature, failure to complete soldering within a
die, ReJA, the thermal resistance from the device jw$on to short time could result in device failure. Therefore, the
following items should always be observed in order to
ambient, and the operating temperature, T~$J1~,n&the minimize the thermal stress to which the devices are
values provided on the data sheet for the SO$F~~~dckage,
PD can be calculated as follows: .qkg$+
#$k\\@h,,$:.’
,>,,., ,<.,
.,,,.,,)
?,.$’..:,,..1;~,,,$.
TJ(max) –TA*2?,.*Y
,~>>;\yp;~.
PD =ROJA,,&V’’’~<%)$?
,.,
$, J
The values for the equa@Wi$#@found in the maximum
ratings table on the data x“~,<~bstituting these values into
the equation for an amb&t’$mperature TA of 25°C, one can
:$,-,<,,,~;’~~.
calculate the pow+’:~~sslp~tlon of the device which in this
case is 225 milli~~~$$$:fi
*,,..b.*
?$,~~.+.~>,*</t\k\,
‘;i%;k~~% 1500c -250c =225 milliwatts
..<:,
........ 556°C~
,*;! ~*..,,
..
:>:? ,::~
.L~@‘%C~ for the SOT–23 package assumes the use
,)::.,>:~,!rt.
:?$q~~~recommended footprint on a glass epoxy printed circuit
‘$$%~dto achieve apower dissipation of 225 milliwatts. There
~e other alternatives to achieving higher power dissipation
from the SOT-23 package. Another alternative would be to
use aceramic substrate or an aluminum core board such as
Thermal Clad’”. Using aboard material such as Thermal
Clad, an aluminum core board, the power dissipation can be
doubled using the same footprint.
@
subjected.
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Always preheat the device.
The delta temperature between the preheat and
soldering should be 10O°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.
Solderina adevice without preheating can cause excessive
thermal sh;ck and stress which can result in damage to the
device.
Motorola Small-Signal Transistors, FETs and Diodes Device Data 3