Industry Encyclopedia

    Three common measures of thermal design:consumption reduction, heat conduction, and layout

    Reduced consumption is not to let the heat generated; thermal conductivity is the heat conduction away from the impact; layout is the heat is not dissipated but through measures to isolate heat-sensitive devices; somewhat similar to the electromagnetic compatibility aspects of the three measures for the emission source, propagation path, sensitive equipment.
    Layout design is often taken:
    1. Components layout to reduce thermal resistance measures: (1) components installed in the best natural heat dissipation location; (2) components heat flow channel to be short, cross-section to be large and no adiabatic or insulation in the channel; (3) heat-generating components scattered installation; (4) components in the printed circuit board vertical discharge. 2. Components emissions to reduce the thermal impact: (1) there are vents inside the chassis. Circuit installation should obey the direction of air flow: air inlet → amplification circuit → logic circuit → sensitive circuit → integrated circuit → small power resistor circuit → with heat generating components circuit → air outlet, constituting a good heat dissipation channel; (2) heat generating components to be above the chassis, heat sensitive components in the chassis below, the use of the chassis metal shell for heat dissipation device. 3. reasonable layout guidelines: (1) the components that generate a lot of heat Installed in good conditions, such as near the ventilation holes; (2) install the heat-sensitive components under the heat source. The lateral surface of the component installation direction is parallel to the wind direction, which is conducive to heat convection. (3) in the natural convection, the heat flow channel as short as possible, the cross-sectional area should be as large as possible; (4) when the cooling airflow velocity is not large, the components are arranged in a forked row way to improve the degree of turbulent airflow and increase the heat dissipation effect; (5) when the heating element is not installed on the housing, the distance between it and the housing should be >35-1000px4. Cooling the air inlet of the internal parts shall be added Filtering device, and do not have to disassemble the housing can be replaced or cleaned. 5. Design to avoid the stability of the device working thermal environment to reduce the thermal cycle and shock caused by temperature stress changes. Temperature change rate does not exceed 1 ℃ / min, temperature change range does not exceed 20 ℃, this indicator requirements can be adjusted by the manufacturer according to the different products. 6. components of the coolant and cooling methods should be compatible with the selected cooling system and components, will not therefore produce chemical reactions or electrolytic corrosion. 7. cooling system electrical power is generally 3% of the required cooling thermal power of 6%; 8. cooling, the airflow Contains moisture, the temperature difference is too large, will produce condensation or adhesion, to prevent water and other pollutants, etc. lead to electrical short circuit, electrical gap reduction or corrosion. Measures: 1). Temperature difference before and after cooling should not be too large; 2). Temperature difference will be too large to produce condensation parts, moisture will not cause blockage or water accumulation, if there is water accumulation, water accumulation parts of the material will not corrode; 3). Heating shrink sleeves or other shielding insulation measures for exposed conductive metal.
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