[VW PCBworld] The complete PCB we envision is usually a regular rectangular shape. Although most designs are indeed rectangular, many designs require irregular-shaped circuit boards, and such shapes are often not easy to design. This article describes how to design irregular-shaped PCBs.

Nowadays, the size of the PCB is shrinking, and the functions in the circuit board are also increasing. Coupled with the increase of the clock speed, the design has become more and more complicated. So, let’s take a look at how to deal with circuit boards with more complex shapes.

Simple PCI board outlines can be easily created in most EDA Layout tools. However, when the circuit board shape needs to be adapted to a complex housing with height restrictions, it is not so easy for PCB designers, because the functions in these tools are not the same as those of mechanical CAD systems. Complex circuit boards are mainly used in explosion-proof enclosures, so they are subject to many mechanical restrictions.

Rebuilding this information in EDA tools may take a long time and is not very effective. Because, the mechanical engineer is likely to have created the enclosure, circuit board shape, mounting hole location, and height restrictions required by the PCB designer.

Due to the arc and radius in the circuit board, the reconstruction time may be longer than expected even if the circuit board shape is not complicated.
　　
However, from today’s consumer electronics products, you will be surprised to find that many projects try to add all the functions in a small package, and this package is not always rectangular. You should think of smartphones and tablets first, but there are many similar examples.　　

If you return the rented car, you may be able to see the waiter read the car information with a handheld scanner, and then wirelessly communicate with the office. The device is also connected to a thermal printer for instant receipt printing. In fact, all these devices use rigid/flexible circuit boards, where traditional PCB circuit boards are interconnected with flexible printed circuits so that they can be folded into a small space.
　　
How to import the defined mechanical engineering specifications into the PCB design tool?

Reusing these data in mechanical drawings can eliminate duplication of work, and more importantly, eliminate human error.
　　
We can use DXF, IDF or ProSTEP format to import all the information into PCB Layout software to solve this problem. This can save a lot of time and eliminate possible human error. Next, we will learn about these formats one by one.

DXF

DXF is the oldest and most widely used format, which mainly exchanges data between mechanical and PCB design domains electronically. AutoCAD developed it in the early 1980s. This format is mainly used for two-dimensional data exchange.

Most PCB tool suppliers support this format, and it does simplify data exchange. DXF import/export requires additional functions to control the layers, different entities and units that will be used in the exchange process.