Internal Bandgap Reference Sensitivity to Board Level Thermal Gradient Shifts
Board level thermal gradients shift internal bandgap voltages by inducing transistor temperature differentials and piezoresistive package stress.
PCB Thermal Impedance
Heat Dissipation
Physical opposition to heat flow through printed circuit board dielectric and copper layers establishes internal temperature rises under operating power loads. Calculated pcb thermal impedance determines the thermal gradient between semiconductor junctions and ambient surroundings, expressed in degrees Celsius per watt. The validity of thermal impedance modeling breaks down under turbulent airflow conditions or fluid immersion scenarios.
Layer Conduction
Heat conducts primary along high-conductivity copper planes within multilayer circuit board stackups. Glass-epoxy FR4 dielectric exhibits low thermal conductivity, creating significant thermal resistance between adjacent layers. Thermal vias arrayed beneath power components bypass dielectric resistance by providing direct metallic heat paths to bottom copper layers.
Surface Convection
Convective heat transfer from outer board surfaces dissipates thermal energy into surrounding ambient air. Enclosure restrictions restrict natural air movement, increasing overall thermal impedance values across board surfaces. Solder mask coatings add minor thermal resistance to convective surface boundaries.
Nearby high-power components elevate local ambient air temperatures, reducing effective heat dissipation capability.
Thermal Verification
Thermal imaging systems map surface temperature distributions under calibrated electrical operating power levels. Calibrated thermal sensors mounted to test points measure local junction rise times to validate substrate thermal models. Calibration standards specify test board geometry and airflow conditions for standardized thermal resistance measurements.