Thermal systems can be considered linear ones. It is evident to generalize the temperature measurement results normalizing them by the applied power. This normalized temperature transient is the Zth curve (sometimes called thermal impedance curve – although in electronics the impedance is interpreted in the frequency domain, not in the time domain).
The temperature transient for any power step can be well estimated using the Zth curve, by simply multiplying each time point by the power. The power step can be negative (cooling) or positive (heating).
The direction of heating is usually positive in Zth curves, Figure 3‑9 comes from Figure 3‑7 dividing it by – 0.2 W.
Figure 3-9: Zth curves of the multi-chip module
These curves can also be manipulated in the T3Ster-Master software for producing ascending or descending curves, fit at different specific points.
