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Computer-aided-design in electronics engineering
posted on June 25, 2020
First things first: CAD means computer-aided-design or computer-aided drafting. One might have some ideas in mind regarding design, like creating appealing visuality or sketching drafts. However, design in mechanics is not only about shapes, but also materials, tolerances, and dimensions. It is rather about the appearance than matching elements. What has to be done to design in the field of mechanics will be deferred to later. Formerly, the design process was done manually by drawing, but nowadays certain software offer support: so-called CAD tools. Those tools for CAD are used for example in the automotive, aerospace, and architectural industry – so basically in every industry that is dealing with design in a technical way. There are indeed many CAD tools on the market. But what are they needed for? All in all, one must know which demands he wants to meet with the software.
Designing in Electronics Engineering
One department, where CAD tools are indispensable is Electronics Engineering. Instead of CAD, we are talking more about Electronic Computer Aided Design Tools (ECAD) or Electronic Design Automation (EDA) here, which are specifically for the tasks of an Electronics Engineer. This allows him to do Computer Aided Engineering (CAE). It has slightly different requirements than the normal CAD tools fitting the needs of the electronics “designer”. What has to be designed in Electronics Engineering are Printed Circuit Boards (PCBs) or electronics systems. As this is a truly complicated task, the tools must be created for this concretely. A circuit board or Printed Circuit Board is an important element of any electronics system. In easy words, it is the brain controlling the parts of the device it is implemented in. You can find it in any electronic devices used daily, such as smartphones and computers and even in a hairdryer, but also in washing machines and driving vehicles. Therefore, the engineer has to know exactly what the PCB should control, which signals it should process. The PCB designer has to choose the elements that are needed on the PCB out of many options for each component. The choice is depending on many factors, as for example:
- the use of the circuit board (what should it control?)
- the environment it will be used in (is it outside, inside, wet, …?)
- the components' compatibility to each other (do they work together, e.g. regarding the voltage?)
After selecting the components, the PCB “designer” places them on the board. There are also certain things to be respected, for example, it should be needed as least space as possible. Sometimes the shape of the device demands a certain shape of the PCB. As the last step, the components need to be connected. This also is a truly complicated task and the board-designer appreciates being supported by a software or more specifically: an ECAD tool.
PCB design back in the days
Formerly, the design process was done manually by drawing. So before CAD, EDA, and ECAD, integrated circuits have also been drawn manually. Pages of lists with numbers and properties had to have been read and interpreted to choose the components for the PCB. The whole process of selection, placing, and connecting can take weeks or months. Therefore, it is in every company’s and engineer’s interest to be supported as well as possible. In the 1970s the first placement and routing tools have been introduced. But one has to say that there is so far no tool combining all steps of automatically designing a PCB meaning you can find a tool for all single steps: Selection, Placing, and Routing. But the first solution combining all these is Celus, which is only possible through using software based on artificial intelligence. Celus is also supporting common tools for integrating the input in the further development steps, independently from the file format.
Differences and functions of CAD tools
Regarding the step of selection, a CAD tool is a great help and digitalizes the manual work. This is what a CAD tool is basically for: Having all requirements and the process of selection collected in digital software. There are cloud-based solutions available making it possible to save huge amounts of data, which is needed when it comes to complicated PCBs. This is one point, where the functionality and demands differ. There are indeed many CAD tools on the market. Some of them are free, some cost a lot of money all providing different functionality. Some are for 2D, others are for 3D modeling. One can say: The cheaper the software, the fewer functions it provides. Cheap or free CAD software enables the engineer to draw digitally, however, he needs to manually implement equations and numbers. The whole work that had been done with pen and paper is now digitalized offering input fields for important information. More expensive software is additionally providing an analysis feature. This means the user has also to implement key figures but the ECAD tool is checking if there are any contradictions. Also when it comes to placing the components and routing, the software is able to point mistakes. This so-called design-rule-check is more comprehensive and reliable the better the software is. Additionally, the better (and mostly therefore the more expensive) the CAD software is, the more complexity it allows regarding the components and design. All in all, one has to know which demands he wants to meet with the software and therefore choose whether a cheap open-source software is sufficient or if a higher quality software is necessary.
Learn using common tools
The described design process is what a student in Electronics Engineering is learning. For this purpose, they learn using common high-quality E-CAD tools, like for example for Altium, Zuken, or Mentor Graphics. In the working life, the students, therefore, do not need to learn how to use Altium designer by Altium, E3 by Zuken, or Pads by Mentor Graphics. Also, some of them might offer a free-trial for students making it easier to learn to create PCBs. Every mentioned software is EDA-software and therefore especially focused on supporting Electronics Engineers. While Pads and E3 offer different versions of the tool to match the requirements, however, the Altium Designer is one of the most used ones on the market. They all offer 3D modeling, which is helpful for the steps of placing and routing. What also makes them a high-quality tool is a good user interface. As the design process is a truly complicated task, the user interface in some CAD tools is confusing or hard to understand for the user. If you want to learn more about Electronics Engineering in general, we can recommend our article about it.