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Temperature Distribution on PCB: Defining Resistance
Posted Aug 29, 2014, 5:44 a.m. EDT Low-Frequency Electromagnetics, Heat Transfer & Phase Change, Geometry, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions 2 Replies
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Hi,
I am trying to simulate a temperature distribution on a PCB.
I have a PCB block, 3 ohmic block shaped resistances, and thin copper plate on the PCB. For the geometry, I used "Block"s (3D) to model those shapes. The physics I am using is Joule Heating (hope this is right). The idea, is to connect a constant current generator to the copper plate, and simulate the temperature distribution.
I need to define 3 different electrical resistance values (in mOhm) for the block shaped resistances. But I couldn't figure out how. Could you please help me on this and give some additional tips on this problem?
Thank you,
Bartu
I am trying to simulate a temperature distribution on a PCB.
I have a PCB block, 3 ohmic block shaped resistances, and thin copper plate on the PCB. For the geometry, I used "Block"s (3D) to model those shapes. The physics I am using is Joule Heating (hope this is right). The idea, is to connect a constant current generator to the copper plate, and simulate the temperature distribution.
I need to define 3 different electrical resistance values (in mOhm) for the block shaped resistances. But I couldn't figure out how. Could you please help me on this and give some additional tips on this problem?
Thank you,
Bartu
2 Replies Last Post Aug 29, 2014, 7:22 a.m. EDT
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Posted:
1 decade ago
Dear Bartu,
in a continuous field model (unlike a discrete circuit) you would not use the resistance (in mOhm) as an input parameter but the actual conductivity of your blocks in S/m (which is the inverse of the resistivity in Ohm*m).
Both are material parameters - the actual resistance of an object is governed by this material quantity *and* the shape or better: the way the current flows through it.
If you do not know this material parameter but only the resistance, what can you do?
1) Ideally, look it up in the literature or possibly our material library.
1) For simple shapes you could also make a first estimate according to the well-known formula using length and cross-section of your resistors.
2) If the shape or current flow are more complex, you could also measure current and voltages on the interfaces of your blocks, calculate the resistance and adjust the conductivity until you have a match.
Best regards,
Sven Friedel
in a continuous field model (unlike a discrete circuit) you would not use the resistance (in mOhm) as an input parameter but the actual conductivity of your blocks in S/m (which is the inverse of the resistivity in Ohm*m).
Both are material parameters - the actual resistance of an object is governed by this material quantity *and* the shape or better: the way the current flows through it.
If you do not know this material parameter but only the resistance, what can you do?
1) Ideally, look it up in the literature or possibly our material library.
1) For simple shapes you could also make a first estimate according to the well-known formula using length and cross-section of your resistors.
2) If the shape or current flow are more complex, you could also measure current and voltages on the interfaces of your blocks, calculate the resistance and adjust the conductivity until you have a match.
Best regards,
Sven Friedel
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Posted:
1 decade ago
Thank you Sven, that was really helpful.