Delphi-like Boundary Condition Independent (BCI) Compact Thermal Models (CTMs) are the standard for modelling single die packages. However their extraction, particularly in the transient case, will be time consuming due to complex numerical simulations for a large number of external conditions. Lately, new approaches to extract a BCI Dynamical CTM (DCTM), based on Model Order Reduction (MOR) have been developed. Despite the numerous advantages of this recent method, the lack of numerical tools to integrate reduced-order models (ROM) makes it difficult to use at board level. In this study, a novel process flow for extracting Delphi-inspired BCI DCTMs is investigated. Thus a detailed three-dimensional model is replaced by a BCI-ROM model using FANTASTIC matrix reduction code to generate the data used in the creation of a Delphi-style BCI DCTM. That hybrid reduction method has been applied to an industrial single-chip package, named QFN16. Its derived CTM and DCTM have been compared in term of accuracy and creation time for both approaches: in-house Delphi-inspired and MOR based. The results show that for a similar accuracy, the integration of MOR technique allows minimizing the time-consuming numerical simulations and so to reduce the thermal network creation time by 80%.

Nowadays, thermal designers have to deal with sophisticated 3D component packaging, enclosing several chips or conventional individually-packaged Integrated circuits with various power densities, embedded in small volumes that will drive up the complexity of their thermal management. Previous analyses were made on system-in-package (SIP) modules to better know the thermal behavior of its encapsulated chips as well as the ability to create a Compact Thermal Model with numerous power sources. These works demonstrated that the creation of thermal resistance networks with n sources, compliant with a large set of realistic boundary conditions, can be achieved with success using superposition principle and Genetic Algorithm (GA) fitting technique. To pursue the development of effective thermal models for DC-DC converter devices, a set of experiments was performed to assess the pertinence of numerical simulations. Thus the upper surface of the asymmetric side-by-sidechips package was subdivided to characterize a set of local maximal and average temperatures. The temperature predictions of the numerical models were compared with the experimental infrared results. The present work describes the process flow that has to be led to generate a detailed numerical model having a low divergence with experimental results. It also declines the creation of DELPHI style models of the discrete sensitive parts of the package, such as inductor device. Each deducted network predicts the monitored key temperatures of the detailed thermal model with a discrepancy lower than 10%. Further a reduction methodology which nests these SubCompact Thermal Models promotes an alternative solution to realize more quickly the generation of a multiple sources thermal resistance networks, according to the boundary condition independent concept [3]. Therefore, the paper summarizes the comparison of a "state-of-the-art" numerical detailed model and its deducted compact model with the help of infrared experimental results in order to establish a modeling guideline.

Planar Magnetic Components are new alternatives to classic transformers. Based on the combination of a low profile high frequency magnetic core and a Printed Circuit Board, these devices allow large reduction in terms of weight and size, which exacerbates power density constraints. To circumvent the potential issues of a multi-layer embedding of flatten high-current-density copper windings at the heart of a substrate, a set of analyses were conducted to characterize electro-thermo-magnetic combined effects with the purpose of elaborating a pertinent thermal model. Using a set of numerical simulations, several concepts of multi-source surrogate thermal model were derived with the prospect of shortening the expensive computation time of the fine Detailed Thermal Model. These approximated models permit to monitor the sensitive temperatures of the primary and secondary windings as well as core ones. Designers can therefore perform trivial calculations to analyse the thermal behaviour of planar transformers for various boundary conditions.