Simulation is a way of predicting reality.\u00a0 The more information we put into the simulation, the better our prediction of what is really going to happen.\u00a0 Certain aspects of electrical simulation, like signal integrity, can be simulated relatively “independently” of other influencing forces.\u00a0 Sure, there are some temperature dependencies on silicon behavior, and those are typically represented by IBIS models created at different temperatures for fast, typical, and slow silicon behavior.\u00a0 And also, the issues of vias tend to complicate things, as they blur the world between traditional signal integrity and power integrity as well as 3D electromagnetic simulation.\u00a0 However, no two disciplines are more closely related than thermal analysis and power integrity, more specifically DC Drop.<\/p>\n
The voltage drop across a plane is determined by the conductivity of the copper.\u00a0 Copper conductivity changes 4% for every 10degC of temperature change.\u00a0 That equates to a 32% change for an 80degC temperature rise, which is pretty significant.\u00a0 So, in order to find an accurate measure of the voltage drop, temperature needs to be included.\u00a0 The other interesting aspect of this is that\u00a0drops in voltage\u00a0mean power is being dissipated by the plane, power that is being dissipated as heat.\u00a0 So, the results of each of these analyses will affect one another.\u00a0 Hence, the need for PI\/Thermal Co-simulation.<\/p>\n