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What is the out-of-plane thickness for?

Posted 10.01.2014, 22:16 GMT-5 Version 4.3, Version 4.3b 5 Replies

Janos Audron
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I have a very simple system as depicted in the picture, I wish to simulate Joule heating of a Pt heater sitting on a SiN membrane. The thickness of the Pt heater will be 20 nm and the SiN membrane will be about 150 nm thick. I've been reading up on the documentation that the out of plane thickness is indeed as the name describes but I don't know how whatever thickness I put in there is used by comsol.

So far, using the geometry attached and using FR4 and Pt from the material library I can get a Joule heating simulation whose temperature changes drastically when I change the out-of-plane thickness from 1e-6m to 1e-7m. At 1e-6m the temperature distribution is essentially constant at 293.16K and at 1e-7m I reach a high temperature of ~550K.

I'm not adding any of the other cooling mechanisms such as convective cooling and surface to ambient radiation yet because I can't make sense out of the current results. However I do have specified one of the edges of the SiN (or FR4) membrane as being at room temperature. I have my terminal and my ground at opposite sides of the wire such that it heats up as expected, but I'm dumbfounded by the radical temperature changes I see upon changing the out of plane thickness by just one order of magnitude.
5 Replies Last Post 14.04.2014, 05:42 GMT-4
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Paolo Picciafoco
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Posted: 1 decade ago 10.04.2014, 03:32 GMT-4

I have a very simple system as depicted in the picture, I wish to simulate Joule heating of a Pt heater sitting on a SiN membrane. The thickness of the Pt heater will be 20 nm and the SiN membrane will be about 150 nm thick. I've been reading up on the documentation that the out of plane thickness is indeed as the name describes but I don't know how whatever thickness I put in there is used by comsol.

So far, using the geometry attached and using FR4 and Pt from the material library I can get a Joule heating simulation whose temperature changes drastically when I change the out-of-plane thickness from 1e-6m to 1e-7m. At 1e-6m the temperature distribution is essentially constant at 293.16K and at 1e-7m I reach a high temperature of ~550K.

I'm not adding any of the other cooling mechanisms such as convective cooling and surface to ambient radiation yet because I can't make sense out of the current results. However I do have specified one of the edges of the SiN (or FR4) membrane as being at room temperature. I have my terminal and my ground at opposite sides of the wire such that it heats up as expected, but I'm dumbfounded by the radical temperature changes I see upon changing the out of plane thickness by just one order of magnitude.


Hi, I've a similar problem. I don't understand how works this parameter. You have found a solution for this? Thank's
[QUOTE] I have a very simple system as depicted in the picture, I wish to simulate Joule heating of a Pt heater sitting on a SiN membrane. The thickness of the Pt heater will be 20 nm and the SiN membrane will be about 150 nm thick. I've been reading up on the documentation that the out of plane thickness is indeed as the name describes but I don't know how whatever thickness I put in there is used by comsol. So far, using the geometry attached and using FR4 and Pt from the material library I can get a Joule heating simulation whose temperature changes drastically when I change the out-of-plane thickness from 1e-6m to 1e-7m. At 1e-6m the temperature distribution is essentially constant at 293.16K and at 1e-7m I reach a high temperature of ~550K. I'm not adding any of the other cooling mechanisms such as convective cooling and surface to ambient radiation yet because I can't make sense out of the current results. However I do have specified one of the edges of the SiN (or FR4) membrane as being at room temperature. I have my terminal and my ground at opposite sides of the wire such that it heats up as expected, but I'm dumbfounded by the radical temperature changes I see upon changing the out of plane thickness by just one order of magnitude. [/QUOTE] Hi, I've a similar problem. I don't understand how works this parameter. You have found a solution for this? Thank's
Jens Krause
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Posted: 1 decade ago 10.04.2014, 03:54 GMT-4
Let me give a generic answer to the term "out-of-plane thickness".
When you do a 2D simulation you
are missing the size of your object in z-direciton (ie out-of-plane) the "out-of-plane thickness"
is the length of the object that Comsol assumes.

For instance if you have a heat source Q on a domain in 3D the unit of Q will be W, but in 2D W/m.
And these values are connected by

Q_3D = Q_2D * out-of-plane-thickness

So when you change the thickness by a factor or 10 also the heat increases by that factor.

Are you sure your 2D model correspons to a cut through 3D structure? (I am no expert in your field)

Regards

Jens
Let me give a generic answer to the term "out-of-plane thickness". When you do a 2D simulation you are missing the size of your object in z-direciton (ie out-of-plane) the "out-of-plane thickness" is the length of the object that Comsol assumes. For instance if you have a heat source Q on a domain in 3D the unit of Q will be W, but in 2D W/m. And these values are connected by Q_3D = Q_2D * out-of-plane-thickness So when you change the thickness by a factor or 10 also the heat increases by that factor. Are you sure your 2D model correspons to a cut through 3D structure? (I am no expert in your field) Regards Jens
Paolo Picciafoco
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Posted: 1 decade ago 10.04.2014, 04:02 GMT-4

Let me give a generic answer to the term "out-of-plane thickness".
When you do a 2D simulation you
are missing the size of your object in z-direciton (ie out-of-plane) the "out-of-plane thickness"
is the length of the object that Comsol assumes.

For instance if you have a heat source Q on a domain in 3D the unit of Q will be W, but in 2D W/m.
And these values are connected by

Q_3D = Q_2D * out-of-plane-thickness

So when you change the thickness by a factor or 10 also the heat increases by that factor.

Are you sure your 2D model correspons to a cut through 3D structure? (I am no expert in your field)

Regards

Jens


Yes, but I don't use 2D model, but only 3D. In a 3D model what's the meaning?
[QUOTE] Let me give a generic answer to the term "out-of-plane thickness". When you do a 2D simulation you are missing the size of your object in z-direciton (ie out-of-plane) the "out-of-plane thickness" is the length of the object that Comsol assumes. For instance if you have a heat source Q on a domain in 3D the unit of Q will be W, but in 2D W/m. And these values are connected by Q_3D = Q_2D * out-of-plane-thickness So when you change the thickness by a factor or 10 also the heat increases by that factor. Are you sure your 2D model correspons to a cut through 3D structure? (I am no expert in your field) Regards Jens [/QUOTE] Yes, but I don't use 2D model, but only 3D. In a 3D model what's the meaning?
Jens Krause
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Posted: 1 decade ago 14.04.2014, 04:17 GMT-4
The pictures in the original post are 2D, so I assumed you are using 2D. There
should be no out-of-plane-thickness in 3D.
The pictures in the original post are 2D, so I assumed you are using 2D. There should be no out-of-plane-thickness in 3D.
Paolo Picciafoco
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Posted: 1 decade ago 14.04.2014, 05:42 GMT-4

The pictures in the original post are 2D, so I assumed you are using 2D. There
should be no out-of-plane-thickness in 3D.


Comsol Staff reply me that is a bug in Joule Heating model for Comsol 4.3b
[QUOTE] The pictures in the original post are 2D, so I assumed you are using 2D. There should be no out-of-plane-thickness in 3D. [/QUOTE] Comsol Staff reply me that is a bug in Joule Heating model for Comsol 4.3b

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