White Paper: Manufacturing & Prototyping

Industry Secrets to PCB Thermal Management

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Keeping electronics at a reasonable temperature is not magic, although it may feel like it at times if you are not very familiar with the rules and situations.

When current flows through a resistor, power is dissipated in the form of heat. With electronic gadgets becoming progressively smaller, heat management is an increasing concern. Unless removed, heat accumulates within the product, causing the temperature to rise and leading to failure. Three physical processes control the movement of heat — conduction, convection, and radiation — with heat flowing from a region of higher temperature towards a region of lower temperature. When dealing with heat management, it is also necessary to deal with two additional factors: thermal resistance and coefficient of thermal expansion.

Just as all materials resist the flow of electric current through them, they also oppose the flow of heat, known as thermal resistance or impedance. Similar to how the electrical resistance of a material produces a voltage difference between two points when a current flows through them, so do thermal resistances create a temperature difference between two points when heat flows through them. Current flowing through a material will produce heat proportional to the product of its electrical resistance and the square of the current flowing through it.

All materials expand or contract to a certain degree when heated. This is an important factor in electronics, especially as many components have interleaving bonding of metallic and nonmetallic surfaces with different coefficients of thermal expansion. Therefore, to manage temperature, electronic designs must consider the effects of conduction, convection, radiation, thermal resistance, and coefficient of thermal expansion.

Please enjoy this white paper from the PCB experts at Advanced Assembly as it walks you through tips and tricks to prepare your PCB design for heat management.

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