Hi there,

my guess is to start with the fact that im one of those newbies.

For a project i'm characterizing inkjet printed silver tracks (i.e. 10 um thickness). At this moment the desired measurements are for resistivity and current carrying capacity (CCC). Both AC and DC measurements are desired. The aim of this project is to build universal measurement set-ups for these kind of materials. (aim of 5% accuracy)

So for resistivity measurement i can simply use 4-points measurement. This isn't too difficult. However, i also want to take temperature changes into account. I.e. when high current/voltage pulses are applied to a track, it will lead to self-heating effects. This self-heating leads to a change in resistance, I want to be aware of these temperature changes as best as possible, like a temp. coefficient. The printed tracks are way to small to do any representive temperature measurements. Now i've talked with some Electrical Engineer about this problem. This friendly guy was talking about determining the tempco. I don't exactly remember, but i think he meant looking for a max frequency of a specific pulse, at which no change in resistance occured. This is where i'm stuck. I have the feeling it should be possible to look for the sort of 'maximum' point of no self-heating and then set up a characterization for beyond that point.

Now i was hoping someone could help me with this part of my project. I don't have a right image of how to determine this temperature-resistance relation properly. Hopefully you're not bothered by my English language skills.

Thanks in advance

 

Can you use a thermal camera, such as a FLIR with higher resolution than the entry level models? Zinc selenide lenses are available at "reasonable" prices. I am assuming that you cannot print directly on a temperature indicating film.

 

Your english is actually pretty good.
What I would do is assume that the material is pretty much homogeneus, and simply put a sample trace into a temperature controlled environment, and measure the change in resistance at different temperature, say for example 30 to 100°C with 10°C step. This will give you a good idea of how the resistance depends on temperature.
Then you can use this information to determine what the temperature of the trace is after you´ve done your pulsed abuse by measuring the resistance. But if the traces are very tiny, they will lose the heat very quickly to the surrounding air and to the base material that they are printed on.

 

The 4 terminal approach will certainly give a reasonable close measure, but you will need to measure both voltage and current , both at the instant of power application and then as time passes to discover how much the material heats and what the resistance change is. So you really need a data acquisition system of some kind.