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.
Thermal Vias
Conductivity Path
Plated through holes in a printed circuit board serve to transfer heat from surface-mounted components toward internal copper planes. These thermal vias operate by reducing the thermal resistance between the semiconductor junction and the external environment. A high density of these structures minimizes the temperature gradient across the substrate.
Heat flow follows the copper walls of the barrel into the inner metal layers which function as a heat sink.
Geometric Constraint
The mechanical design of these features relies upon the drill diameter and the copper plating thickness. Smaller hole diameters limit the volume of metal deposited within the barrel during the plating process. Large arrays provide a lower resistance path but occupy significant board real estate.
Designers calculate the total cross-sectional area to determine the effective rate of heat extraction.
Electrical Interference
Proper board layout requires isolation between the heat dissipation network and sensitive signal traces. Parasitic capacitance arises when these structures reside near high-frequency lines. Grounding these paths at both ends prevents electromagnetic coupling into the surrounding circuit.
A well-designed stack-up maintains board integrity while managing local heat loads.
Manufacturing Variance
Variation in plating uniformity across the board surface affects the performance of each individual hole. Consistent chemical concentration in the deposition bath dictates the final conductivity of the copper wall. Excess flux or residual debris within the hole blocks the intended heat path during assembly.
Measured impedance testing verifies the continuity and thickness of the plated material against specified tolerances.