For electronic equipment, a certain amount of heat is generated during operation, so that the internal temperature of the equipment rises rapidly. If the heat is not dissipated in time, the equipment will continue to heat up, and the device will fail due to overheating. The reliability of the electronic equipment Performance will decrease.
Therefore, it is very important to conduct a good heat dissipation treatment on the circuit board. The heat dissipation of the PCB circuit board is a very important part, so what is the heat dissipation technique of the PCB circuit board, let's discuss it together below.
Heat dissipation through the PCB board itself The currently widely used PCB boards are copper clad/epoxy glass cloth substrates or phenolic resin glass cloth substrates, and a small amount of paper-based copper clad boards are used.
Although these substrates have excellent electrical properties and processing properties, they have poor heat dissipation. As a heat dissipation method for high-heating components, it is almost impossible to expect heat from the PCB itself to conduct heat, but to dissipate heat from the surface of the component to the surrounding air.
However, as electronic products have entered the era of miniaturization of components, high-density mounting, and high-heating assembly, it is not enough to rely on the surface of a component with a very small surface area to dissipate heat.
At the same time, due to the massive use of surface mount components such as QFP and BGA, the heat generated by the components is transferred to the PCB board in a large amount. Therefore, the best way to solve the heat dissipation is to improve the heat dissipation capacity of the PCB itself that is in direct contact with the
▼Heat viaheating element. Conducted or radiated.
▼Heat viaBelow is Heat Via
Exposure of copper on the back of the IC reduces the thermal resistance between the copper and air
PCB layout
Thermal sensitive devices are placed in the cold wind area.
The temperature detection device is placed in the hottest position.
The devices on the same printed board should be arranged as far as possible according to their calorific value and degree of heat dissipation. Devices with low calorific value or poor heat resistance (such as small signal transistors, small-scale integrated circuits, electrolytic capacitors, etc.) should be placed in the cooling airflow. The uppermost flow (at the entrance), the devices with large heat or heat resistance (such as power transistors, large-scale integrated circuits, etc.) are placed at the most downstream of the cooling airflow.
In the horizontal direction, high-power devices are placed as close to the edge of the printed board as possible to shorten the heat transfer path; in the vertical direction, high-power devices are placed as close to the top of the printed board as possible to reduce the impact of these devices on the temperature of other devices .
The heat dissipation of the printed board in the equipment mainly relies on 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 always tends to flow in places with low resistance, so when configuring devices 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.
The temperature-sensitive device is best placed in the lowest temperature area (such as the bottom of the device). Never place it directly above the heating device. It is best to stagger multiple devices on the horizontal plane.
The devices with the highest power consumption and heat generation are arranged near the best position for heat dissipation. Do not place high-heating devices on the corners and peripheral edges of the printed board, unless a heat sink is arranged near it.
When designing the power resistor, choose a larger device as much as possible, and make it have enough space for heat dissipation when adjusting the layout of the printed board.
Recommended component spacing: