BCW30LT1
INFORMATION FOR USING THE SOT–23 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.
0.037
0.95
0.037
0.95
0.079
2.0
0.035
0.9
0.031
0.8
inches
mm
SOT–23
SOT–23 POWER DISSIPATION
The power dissipation of the SOT–23 is a function of the
SOLDERING PRECAUTIONS
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
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.
by T
die, R
, the maximum rated junction temperature of the
, the thermal resistance from the device junction to
J(max)
θJA
ambient, and the operating temperature, T . Using the values
provided on the data sheet for the SOT–23 package, P can
A
D
be calculated as follows:
• Always preheat the device.
T
– T
A
• The delta temperature between the preheat and
soldering should be 100°C or less.*
J(max)
P
=
D
R
θJA
• 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.
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 of 25°C,
A
one can calculate the power dissipation of the device which
in this case is 225 milliwatts.
150°C – 25°C
556°C/W
P
=
= 225 milliwatts
D
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 225 milliwatts.
There are other alternatives to achieving higher power
dissipation from the SOT–23 package. 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.
* Soldering a device without preheating can cause
excessive thermal shock and stress which can result in
damage to the device.
http://onsemi.com
7
5秒后页面跳转
STM32H743技术深度剖析与应用案例探索
LM321中文资料解析：引脚功能介绍、技术特点、技术特性分析
74HC14芯片资料介绍：性能特性分析、引脚介绍
LM1875芯片手册：功放参数分析、引脚说明、电路设计要点
微信公众号
抖音公众号
浙公网安备 33010502006866号 浙ICP备10014259号-119
营业执照ICP证
技术参数
数据手册
如果您发现信息不准确，
