For electronic equipment, a certain amount
of heat is generated during work, which causes the internal temperature of the
equipment to rise rapidly. If the heat is not released in time, the equipment
will continue to heat up and the device will fail due to overheating.
Performance will degrade. Therefore, it is very important to perform a good
heat dissipation process on the circuit board.
1. Add heat dissipation copper foil and
copper foil with large area power supply.
The larger the area connected to the copper
skin, the lower the junction temperature.
2. Thermal vias
Thermal vias can effectively reduce the
junction temperature of the device, improve the temperature uniformity in the
thickness direction of the board, and provide the possibility to adopt other
heat dissipation methods on the back of the PCB. Through simulation, it is
found that compared with no thermal vias, thermal vias with a device thermal
power consumption of 2.5W, a pitch of 1mm, and a center design of 6x6 can reduce the junction
temperature by about 4.8 ° C, and the temperature difference between the top
and bottom surfaces of the PCB Reduced from 21 ° C to 5 ° C. After the thermal
via array is changed to 4x4, the junction temperature of the device is 2.2 ° C
higher than that of 6x6, which is worthy of attention.
3. Copper is exposed on the back of the IC
to reduce the thermal resistance between the copper skin and the air
4.PCB layout
Requirements for high-power,
thermal-sensitive devices.
a. The heat sensitive device is placed in
the cold wind area.
b. The temperature detection device is
placed in the hottest position.
c. The devices on the same printed board
should be arranged as much as possible according to the amount of heat
generated and the degree of heat dissipation. Devices with low heat generation
or poor heat resistance (such as small signal transistors, small-scale
integrated circuits, electrolytic capacitors, etc.) should be placed. At the
top of the cooling airflow (at the entrance), devices with high heat generation
or heat resistance (such as power transistors, large-scale integrated circuits,
etc.) are placed at the most downstream of the cooling airflow.
d. In the horizontal direction, the
high-power devices should be arranged as close to the edge of the printed board
as possible to shorten the heat transfer path; in the vertical direction, the
high-power devices should be arranged as close to the top of the printed board
as possible to reduce the temperature of these devices when they are working.
Impact.
e. The heat dissipation of the printed
board in the device mainly depends on the air flow, so the air flow path should
be studied during the design, and the device or printed circuit board should be
reasonably configured. When air flows, it tends to flow in a place with low
resistance, so when configuring the device on a printed circuit board, avoid leaving
a large airspace in a certain area. The configuration of multiple printed
circuit boards in the whole machine should also pay attention to the same
problem.
f. The temperature-sensitive devices are
best placed in the lowest temperature area (such as the bottom of the device).
Do not place it directly above the heating device. Multiple devices are
preferably staggered on the horizontal plane.
g. Place the device with the highest power
consumption and heat generation near the best position for heat dissipation. Do
not place devices with high heat generation at the corners and peripheral edges
of the printed board, unless a heat sink is arranged near it. When designing
the power resistor, select a larger device as much as possible, and make sure
that there is enough space for heat dissipation when adjusting the layout of
the printed board.
