PCBA Tech - How does PCB dissipate heat during PCB manufacturing?

The heat generated during the operation of PCBA technical equipment of PCBA manufacturer will cause the internal temperature of the equipment to rise rapidly. If the heat is not dissipated in time, the equipment will continue to rise, the devices on PCBA board will fail due to overheating, and the reliability of electronic equipment will decline; Therefore, the heat dissipation treatment of PCBA board is a very important work link.

1, PCBA temperature rise factor analysis: the direct cause of PCB temperature rise is due to the existence of circuit power consumption devices, electronic components will have power consumption in varying degrees, and the heating intensity changes with the size of power consumption. Two phenomena of temperature rise in printed boards: (1) local temperature rise or large area temperature rise; (2) Short time temperature rise or long time temperature rise.

When analyzing the time-consuming of PCBA thermal power, it usually needs to be analyzed from several aspects: 1. Electrical power consumption (1) analyze the power consumption per unit area; (2) The distribution of power consumption on PCBA circuit board is analyzed. 2. Structure of printed board (1) size of printed board; (2) Materials of printed boards.

The analysis of the above factors from PCBA is an effective way to solve the temperature rise of printed board. Often in a product and system, these factors are interrelated and dependent. Most factors should be analyzed according to the actual situation. Only for a specific actual situation can the parameters such as temperature rise and power consumption be calculated or estimated correctly.

2, Cooling mode of circuit board:

1. Heat sink and heat conduction plate for high heating components: when a few components in PCBA circuit board have large heating capacity (less than 3), heat sink or heat conduction pipe can be added to the heating PCBA board components. When the temperature cannot be reduced, heat sink with fan can be used to enhance the heat dissipation effect. When there are more PCBA heating devices (more than 3), a large heat dissipation cover (plate) can be used, which is a special radiator customized according to the position and height of the heating devices on the PCBA board, or different component height positions can be pulled out on a large flat radiator; The heat dissipation cover is buckled on the component surface as a whole and contacts with each component to dissipate heat. However, due to the poor consistency of components during assembly and welding, the heat dissipation effect is not good. Usually, a soft thermal phase change heat conduction pad is added on the surface of PCBA components to improve the heat dissipation effect.

3. Heat dissipation through PCBA plate itself: at present, PCBA plate widely used by PCBA plate manufacturers is copper-clad / epoxy glass cloth substrate or phenolic resin glass cloth substrate, and a few PCBA manufacturers use paper-based copper-clad plate; Although these substrates have excellent electrical and processing properties, they have poor heat dissipation. As a heat dissipation path of high heating elements, it is almost impossible to expect heat to be transmitted by the resin of PCBA itself, but heat is dissipated from the surface of PCBA plate elements to the surrounding air. However, as electronic products have entered the era of component miniaturization, high-density installation and high heating assembly, it is not enough to dissipate heat only on the component surface with a very small surface PCBA area. At the same time, due to the extensive use of surface mounted components such as QFP and BGA, a large amount of heat generated by the components is transmitted to the PCBA board. Therefore, the best way to solve the heat dissipation is to improve the heat dissipation capacity of the PCBA circuit board in direct contact with the heating elements, which is transmitted or distributed through the PCBA board.

4. PCBA manufacturer's PCBA workshop must adopt reasonable wiring design to realize heat dissipation: since the thermal conductivity of resin in most PCBA plates is very poor, and copper foil lines and holes are good conductors of heat, PCBA technology PCBA manufacturer's main means of heat dissipation is to improve the residual rate of copper foil and increase heat conduction holes; When evaluating the heat dissipation capacity of PCBA, PCBA technical engineers need to calculate the composite material PCBA composed of various materials with different thermal conductivity of PCBA by using the equivalent thermal conductivity (nine EQ) of insulating substrate.