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In the beginning of our universe, enormous amount of heat or energy was generated and released during the period of 0 to 10-43 sec, in theory while backed up by models and measurements, about 13.8 billion years ago. Since then, a variety of physical mechanisms keep transforming the energy into other forms or converting it back as heat, including the nuclear fusion in our sun and the self-heating within the tiny transistors on the computer chips in our electronic devices. For every system to function well, no matter it is a live organism like a virus or a man-made device like a smart phone, the operational temperature range will be one of the most essential factors directly related to the system agility. Consequently, thermal analysis that can reveal temperature information or distribution within the system under various desired conditions of energy input and output would be among the core elements to ensure the operation and performance of the system.
The on-chip thermal analysis has been weighed among developers as one of the critical requirements for electronic system designs. In essence, thermal transport is a diffusion process, which is different from electric transport in circuits. Electrical currents are flowing through electrically conductive paths, and the relevant electrical characteristics are mostly limited to the conductive paths (metals). Dielectric materials usually come into the picture in the assessment of electromagnetic interaction and dielectric breakdown under large electrical potential differences. On the other hand, heat will diffuse through all materials in the system, although heat conduction is typically much more effective in metals than in dielectrics. This is the main reason that for a system-level heat transfer analysis, all materials physically existing in a system should be included. In addition to the fact that thermal transport has a nature of involving both metals and dielectrics, several aspects associated with the importance and challenges of on-chip thermal analysis are detailed below:
Chip design Chip power profiling System thermal analysis
System-level transient thermal analysis: temperature distribution as time marching
System configuration Temperature distribution Velocity streamlines
Heterogeneous packaging structure Exemplary temperature profile
Celsius Thermal Solver was developed aiming to respond those challenges. To precisely obtain the power profiling on chips, Celsius can connect with the thermal model generated by Voltus based on the proven power analysis technology widely adopted by IC designers. The Voltus thermal models contain necessary physical parameters including detailed power distribution, material properties, and metal density information at different layers inside the chip. The power distribution can be in both steady and transient states for subsequent electrical-thermal co-simulation. Celsius can also incorporate detailed or simplified models for the package, PCB, and enclosure designs of the system to ensure the heat transfer from the chips to the environment is adequately considered. In particular, the Computational Fluid Dynamics (CFD) module is integrated with the Finite-Element-Analysis (FEA) module on a common platform to provide a complete approach for system-level thermal problems. Combining its unique features and readily integration with existing Cadence tools, Celsius Thermal Solver clearly would provide the holistic solution to address the on-chip thermal challenges in electronic system designs.