What is ECAD and why is it Used in FEA?
Phil Kinnane September 18, 2012
In short, electronic computer-aided design (ECAD) is typically used to design and develop electronic systems. Although it’s a mere letter away from spelling out “CAD”, there’s actually more to the story than appending the word “electronic” to “CAD”. So what is ECAD and why is it used in Finite Element Analysis (FEA)?
Computer-Aided Design (CAD)
Let’s begin by discussing CAD. The engineer creates the design in 2D or 3D where data describing the different dimensions’ positions in space are available in CAD files. Previously, these drawings gave great insight into the design of a part or assembly, and the dimensions would be manually read-off by the engineers that would build the desired product. But these days, CAD files can also be complemented by further data, such as describing the material property of a part or its tolerances. The files can be automatically read by tools that need to work with the designs, such as the machines in the manufacturing process or the software that run FEA.
Electronic Computer-Aided Design (ECAD)
While CAD is usually used for designing a specific part or an assembly, ECAD is used to design an entire system of many components connected to each other, usually by electric circuits — think the circuit board in your computer. The intricacies of these types of designs are often quite complex for a CAD software to handle in an effective way. Looking down on a circuit board, you can see that it is quite complex. But if you look from the side, you can see that most of the components making up the circuit board are quite regular.
Electrical Engineers have found that it is a lot simpler to design their integrated circuits (ICs) in 2D, where all the complexity of positional data can be effectively evaluated and assessed. This dimensional data is then incorporated with extra data, such as the height of the circuit board layers and their material properties, in an ECAD file as metadata. ECAD files are perfect for the manufacturing industry as most ICs are produced by depositing metal and oxide layers through “masks”. The 2D data is basically the layout of the mask, while the ECAD file’s metadata instructs the manufacturing process on the material type and amount of material to be deposited.
Example of an integrated circuit.
Yet, going directly from ECAD to manufacturing is becoming less viable as IC designs are customized, become smaller, and material waste needs to be minimized. As these designs are optimized, the components making up electrical systems need to be analyzed to their established behavior within the system (such as the effects of joule heating) as well as to external factors (how to effectively cool them). This is where simulation such as FEA comes into the picture. With FEA, the separate components of an IC can be tested before the final design is submitted for manufacture.
ECAD and FEA
Reading ECAD files to perform FEA requires building the 3D objects from 2D dimensional data and the accompanying metadata. You can currently do this with COMSOL’s AC/DC, MEMS, and RF Modules, which are all applicable for modeling the electromagnetic and, with the MEMS Module, structural behavior of IC components. But what about the engineers who don’t have one of these Modules but are interested in modeling electronics applications?