# Determining the relation between resistance and heat (printed electronics)

#### daanmicro

Joined Nov 15, 2017
50
Hi there!

First of all i'm gonna excuse myself for my English skills, they're not that bad but perhaps it generates some sympathy.

I'm working on a Printed Components Characterization project, and right now i'm investigating the heating of inkjet printed silver ink tracks. For this i now own a function generator, a silicone heating mat, oscilloscope, and all the cables, clamps, probes etc ofcourse.

I know (or guess(?)) i can set up a characterization of R as a function of T and R as a function of t, t is in this case the duration of a pulse (incoming crappy paint drawing!) . Someone has told me i'll have to combine the t of the voltage pulse on the scope, when it reaches a certain equilibrium, with the resistance R.

By the way i've got no electrical background so i'm sort of new in this scene. Would anyone be able to help me further with this case?

Which voltages / currents do i need?
How the hell can i convert an R(T) and R(t) measurement to a useful characterization, after which i can determine/estimate the heating with a certain pulse (known current and pulse duration).

Kind regards

#### kubeek

Joined Sep 20, 2005
5,751
So what is it exactly that you want to characterize? Is it the properties of the tracks themselves, or in combination with some known substrate and ambient conditions?
In your last thread you were looking for a thermal coefficient and current carying capability.

#### daanmicro

Joined Nov 15, 2017
50
So what is it exactly that you want to characterize? Is it the properties of the tracks themselves, or in combination with some known substrate and ambient conditions?
In your last thread you were looking for a thermal coefficient and current carying capability.
Yess, i can understand your curiosity. I'm characterizing different components like silver tracks, vias, capacitors. The properties that are desired to be tested are Resistivity, CCC, Capacity/inductance, Thermal conductivity, quality and probably some more. So i hope you can see the full picture, that there's a lot to be tested and a lot is unknown yet.

So my whole project is a pretty big mixup, divided in different measurement set-ups which will have to be built first. I'm really willing to dive into this stuff, but for now my knowledge is pretty limited on this subject.

Edit: The substrate won't vary much.So this is mostly about the tracks themselves.

#### daanmicro

Joined Nov 15, 2017
50
But anyhow, could anyone tell me how i convert an R(T) and R(t) measurement to a useful characterization, after which i can determine/estimate the temperature as a function of a certain pulse duration?

#### ArakelTheDragon

Joined Nov 18, 2016
1,353
I am not certain I understand, but what you want is to see how the temperature will behave depending on the pulse length?

If so, what you need is a slope which shows the temperature rises until it reached its nominal and then you have a straight line until the end of the impulse. When the impulse shuts down you have a slope until the temperature falls down and then the next impulse does the same. This looks like to me as an attempt to estimate the efficiency of some product. Which means you think manufacturers sell you junk intentionally, so they can tell you buy the better one, and you are right. Sometimes they decrease the quality on purpose so they can tell you buy the new model.

#### daanmicro

Joined Nov 15, 2017
50
Thanks. That's what i meant indeed,Yass i'm looking for that slope going to a nominal value eventually. But the thing is i'm not able to measure the temperature of these tracks due to their small sizes (micrometers). So i can't really measure this fall of the temperature.

So what i'm willing to find out, and in my imagination it should be possible, is to link these (current) pulses to a certain temperature (or temp. rise). I've got a heating mat to determine a value for R depending on T. Now i want to link this R(T) (or T(R) you name it) to the function of time versus temperature.

I can imagine i'm talking nonsense right now, then excuse me for that. Still a great noob at this

#### ArakelTheDragon

Joined Nov 18, 2016
1,353
Thanks. That's what i meant indeed,Yass i'm looking for that slope going to a nominal value eventually. But the thing is i'm not able to measure the temperature of these tracks due to their small sizes (micrometers). So i can't really measure this fall of the temperature.

So what i'm willing to find out, and in my imagination it should be possible, is to link these (current) pulses to a certain temperature (or temp. rise). I've got a heating mat to determine a value for R depending on T. Now i want to link this R(T) (or T(R) you name it) to the function of time versus temperature.

I can imagine i'm talking nonsense right now, then excuse me for that. Still a great noob at this
This is not as simple as ot looks. You can not link the current to temperature. You can link the power to the temperature. What will be the power for these tracks? They will heat up with 10W until they reach nominal and dissipate at room temperature with no air flow?

This is a measurement done for a certain amount of time. What you need is to find the heat build up and dissipation times (rising temperature and falling temperature respectively). I think there should be some online table or calculator for this. Are you trying to test if your tracks will stand up to the current you pass through them? That can be calculated through power?

#### WBahn

Joined Mar 31, 2012
26,398
Thanks. That's what i meant indeed,Yass i'm looking for that slope going to a nominal value eventually. But the thing is i'm not able to measure the temperature of these tracks due to their small sizes (micrometers). So i can't really measure this fall of the temperature.
Micrometer scale printed silver tracks?