PCB thermal resistance

[shauns87]

Is there a way to calculate overall PCB thermal resistance or thermal conductivity of a PCB based on the PCB stackup information? I would like to use this input in thermal analysis of the PCB. Thanks.

 

[D.A.(Tony)Stewart]

Can you be more specific?

PCB Substrates: Knowing PCB Dielectric Materials | Sierra Circuits

A PCB substrate or dielectric material conducts minimal electricity and provides an insulating layer between two conducting copper layers.

www.protoexpress.com

 

[KlausST]

Hi,

It's like asking the distance from a person to his/her mother.

It highly depends..... on multiple factors.
From which position to which position, distance, area, material, stackup, layers.....

Klaus

 

[FvM]

What do you mean with "overall PCB resistance"? Is it Rth between a single component on the PCB and ambient? If so, it's a 3D problem, depending on the parameters mentioned by KlausST, in addition PCB orientation, airflow respectively convection conditions.

An exact analysis is very complex, there are professional tools like 6Sigma performing it based on a geometry model.

 

[D.A.(Tony)Stewart]

Are you looking for a book on how to thermal design on the PCB or a simple question like total power is with N pwr. chips.

Have you considered sinkpads? Alumclad substrates? Thermal vias? Heat Flow of enclosure's thermal resistance , closed, vs open vs orientation, vs forced air?

 

[ViasionTech]

PCB thermal resistance can be measured using the guarded hot plate method or the 3-omega method. The guarded hot plate method is by far the easiest method as you simply measure the temperature on two sides of a board as heat transfers from the hot side of the circuit board to the cold side. This provides a simple way to directly measure the thermal conductance, which can then be used to calculate thermal conductivity and thermal resistance. The 3-omega method is a thermoelectric method, where the board is heated with an AC heater at a specific frequency. This induces periodic heating at double the frequency. The measured temperature signal will contain components at the heating frequency and triple the frequency, this is the name “3-omega.” The thermal conductivity of the test coupon is proportional to the strength of these frequency components and the geometry of the test coupon.