Measurement of simulated active device and RF trace heating in high frequency circuit laminates

Abstract

Purpose -The purpose of this paper is to quantify the effects of thermal conductivity (TC), dielectric constant and dissipation factor (DF) of circuit laminates on the temperature rise with active components and RF trace heating. Design/methodology/approach -Temperature rise measurements were made on surface mounted chip resistors (to simulate active components) at various dissipated power levels, with and without "via farms". The RF heating temperature rise of 50 ohm microstrip transmission lines on 0.5 mm laminates was also measured by the same method. Findings -The chip resistor temperature rise correlated with the independently measured TC of the laminate materials. The use of a "via farm" substantially reduced the temperature rise in all materials, but the higher TC laminates still conferred a measurable advantage. The trace temperature rise due to RF heating correlated with both TC and DF. Research limitations/implications -It was shown that the one-dimensional heat transfer model does not accurately calculate the temperature rise due to significant in-plane heat spreading, particularly with lower TC materials. Originality/value -This paper details how temperature rise of both active components and 50 ohm transmission lines is affected by the thermal and electrical properties of the circuit laminate.

Copper coin-embedded printed circuit board for heat dissipation: manufacture, thermal simulation and reliability

“…Highly conductive inorganic fillers have also been added into insulating polymers to improve the heat dissipation, as most of the dielectric materials for PCBs are amorphous polymers with phonon scattering from numerous defects, leading to an extremely low thermal conductivity (Chen et al, 2013;Li et al, 2011;Jin et al, 2012). However, pure metals, with free electrons for rapid heat transport, possess such high thermal conductivities that metal plates can be used as heat sinks to significantly enhance the thermal design loads of PCBs (Chen et al, 2014b;Caisse et al, 2011;Buck, 1992). A PCB is usually bonded by means of an adhesive film with a whole metal plate as a bottom layer or a core inlayer to give a heat-dissipating construction (Wille, 2008;Cho and Hyeong, 2008) but this method can result in an increase both in the volume and weight of the PCB.…”