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PCB Thermal Design
Apr 30, 2018

The purpose of PCB thermal design is to take appropriate measures and methods to reduce the temperature of the components and the temperature of the PCB, so that the system can work properly at the right temperature. This article mainly discusses the thermal design of the board circuit and its implementation method from the aspects of reducing the heat generation of the heating element and accelerating the heat dissipation.

1, reduce the heat

There are three main sources of heat in the PCB: 

(1) heating of the PCB itself;  

(2) heating of electronic components;

(3) heat from other parts. Among these three heat sources, the components generate the largest amount of heat, which is the main source of heat, followed by the heat generated by the PCB. The heat output of the components is determined by their power consumption. Therefore, the power consumption should be low at the time of design. Components, minimize heat generation. Followed by the setting of the component work, generally should be selected in its rated working range, when the scope of work again when the performance is good, low power consumption, longest life. Power amplifier devices themselves have a large amount of heat, and they are designed to avoid full-load operation. For high-power devices, the principle of derating should be implemented, and the design affluence should be appropriately increased. This is beneficial for increasing system stability, reliability, and reducing heat generation. PCB board heat due to the resistance of the circuit itself, as well as exchange, high-frequency heating heat. The PCB is composed of a copper conductor and an insulating dielectric material, and generally the thermal insulating material does not generate heat. The copper conductor pattern has a resistance due to the copper itself, and generates heat when the current passes through it.

2, speed up heat dissipation

Under given conditions, when the temperature of the components in the board-level circuit rises above the reliability guaranteed temperature, appropriate heat-dissipation countermeasures must be taken to reduce the temperature to the reliability operating range. This is the final result of our thermal design. purpose. Heat dissipation is the main content of PCB design. For the PCB, its heat dissipation is nothing more than three basic types: heat conduction, convection, and radiation. Radiating type uses the electromagnetic wave motion that listens to the space to dissipate the heat, its heat dissipation is smaller, usually as the auxiliary heat dissipation means. Thermal conduction and convection are the main means of heat dissipation. Our commonly used cooling methods:

1 Use heat sinks to pour heat out of the heat source and use air convection to disperse it;

2 Plates with good performance of thermal conductivity: Epoxy glass cloth sheets, which are widely used today, have a thermal conductivity of 0.2 W/m°C. Common electronic circuits usually use epoxy glass cloth base materials because of their small heat generation. The small amount of heat they generate is generally emitted through the thermal design of the wiring and the components themselves. With the miniaturization, high integration, and high frequency of components, the thermal density has been significantly increased. In particular, the use of devices at the kilometer has led to the development of a number of new thermal conductive plates to meet this high heat dissipation requirement. Such as metal substrate, Rogers series material.

3 through the optimization of components arranged to improve heat dissipation; according to the thermal requirements of the component layout; staggered disperse arrangement: in the layout of the layout of the layout of the components, the heat components should be distinguished from the general devices and temperature sensors, heating devices should be left around Adequate heat-dissipating gas flow channels, and the heating elements should be staggered and arranged in an array, which is just the opposite to the regular layout in the usual layout, which is beneficial to improving the heat dissipation effect.