Quick And Dirty Thermal?

It's been said before:

Is this a true statement about Sauna?

Sure, Sauna can create quick models. For example, it only takes a minute or two for a heat sink model. Then it's a simple matter to calculate temperatures for both natural and forced air cooling. Want to look at different fin spacings or fin lengths? This is easily done with Sauna.

What about boxes? Sauna has specialized commands for creating a six-sided box and additional commands for adding a board or shelf within the box. You can add fins to any wall in the box. Heat input can be defined with point heat sources or a distributed head load. So Sauna can create quick box models as well.

What about multilayer boards? This problem is complicated because of the need to deal with multiple copper planes, traces and vias. Many thermal modeling programs struggle with multilayer boards and force the user to apply a "copper volume percentage" to account for vias and traces. This is a crude approach that does not lead to accurate results. Sauna's method is much more refined. You can quickly create the different copper planes, with different plating weight and trace density for each layer. Initially, each copper plane has uniform trace density, but this can be modified to vary within the plane. Another challenge is modeling the thermal resistance between copper layers. This can be complex because via densities and diameters can vary significantly across the board. But Sauna can handle this. For a quick model, Sauna let's you use simplified via densities of ""Low", "Medium", "High", and "None". Later, as required, you can use a more precise via thermal resistance definition. So the answer is: "Yes, Sauna can create quick models of multilayer boards that include variable copper planes and via densities".

OK, so the quick part is covered. However, we hesitate to refer to Sauna as quick and dirty. Dirty implies a rough extrapolation of some previous calculation or measurement. In fact, Sauna only uses carefully verified libraries and properties, and very standard heat transfer equations. Sauna has an extensive performance record, as the program has been in commercial use since 1989. There's nothing dirty about the temperatures predicted by Sauna.

But another comment needs to be made. Although Sauna excels at quick models, Sauna also has many sophisticated features. For example, thermal radiation analysis is an important part of electronics cooling, particularly for natural cooling. Sauna incorporates advanced gray radiation analysis with automatic calculation of view factors. Some thermal programs have these features, many do not. Since many components have dissipation that varies with operating temperature, Sauna provides control elements. To handle power that cycles on and off, as well as power surges, Sauna MS includes duty cycle transient. You may find these features in other programs, but don't expect quick calculation times or a simple interface.

And you're certainly not limited to simple geometric representations. At one extreme, you can perform microscale analysis of chip stackups. At the other limit, you can model meter-sized boxes. And you can place a microscale stackup within a large box model.

So, is Sauna a quick and dirty thermal program? The answer is "Yes, if you want it to be". Just remember that Sauna is a sophisticated tool that can provide accurate results for an extremely wide variety of problems. The price is attractive too!