Solid Freeform Fabrication Targeted PCB Design

Key Takeaways

• What is solid freeform fabrication (SFF)?

• How does SFF affect PCBA prototyping? 

• How to design boards for SFF processing.

Solid freeform fabrication machine.

As the usage of electronics and circuit boards continues to find its way into virtually every machine, device, and activity that we use for work or recreation, the techniques and methods by which boards are built continue to evolve as well. These advancements are often demand-driven to achieve higher quality and greater functionality. Certainly, the market and competition therein play a significant role in driving faster development and production.  And just as more knowledge whets the appetite for further study, faster, smaller, and smarter devices, appliances, and vehicles reveal more opportunities for PCBA application and optimization.

There are a number of manufacturing techniques to emerge recently for PCB fabrication.  A common theme for many of them is the shift from a 2D to a 3D modeling design perspective. Doing so is necessary to create boards intended for what is most often referred to as three-dimensional (3D) printing. 

There is a lot to be excited about when it comes to 3D printing, such as the ability for an engineer to design, build, and test a design without leaving his or her work station.  Exciting, indeed! Before we get too carried away, however, let’s take a look at the larger area of solid freeform fabrication, its impact on PCBA development, and how you can design to fully leverage this technology.  

What Is Solid Freeform Fabrication?

Engineers have a knack for creating new terminology, which is often used to differentiate between some material or process enhancement that advances a product or technology beyond its previous state. And, as solid freeform fabrication is sometimes confused with other terms, it is probably best to describe it in context with other terms that may have similar definitions. 

Definitions:

🖶    Rapid Prototyping

The term rapid prototyping is used to signify manufacturing methods that are intended to optimize the speed of the prototyping process.

🖶    Additive Manufacturing

Additive manufacturing refers to the “building up” of a product by adding successive layers, as opposed to subtractive manufacturing where the process begins with a larger solid and removes material to achieve the desired product.

🖶    Three-Dimensional (3D) Printing

3D printing can generally be defined as the construction of a 3D product from a 3D

digital model using an additive manufacturing technique.

🖶    Solid Freeform Fabrication

Solid freeform fabrication is a 3D printing process performed where a product is constructed without the need for any human aid or interaction and no additional specifically tooled parts or components are required.

From these definitions, it is obvious how these terms can be misinterpreted or incorrectly used interchangeably. Armed with an accurate description of solid freeform fabrication (SFF), we are ready to explore how this rapid prototyping technique impacts the development of your boards.

PCBA Development with SFF

Different solid freeform fabrication setups. (Image source)

As shown in the figure above, there are several different methods or techniques of SFF. Each of these has the advantage of providing a means to improve the speed of development for your circuit board as design, build, and testing can be performed at the same location. To gain a full appreciation of the impact of SFF on PCBA development, the important attributes of SFF and contemporary PCB fabrication are compared in the following table. 

As shown above, SFF compares favorably to contemporary fabrication in the key areas of turnaround time, cost, and waste. Additionally, SFF has progressed to a level where the manufacturing quality and reliability of the boards is more than sufficient for PCB prototyping.  

There is continual research into multiple-material SFF to improve board complexity, capability, and to optimize discrete component fabrication. Currently, the layout and routing for SFF built boards can be comparable to PCBs built in fab houses, provided the design model is sufficiently detailed and accurate. Let’s see how to ensure the design model is best prepared for manufacturing using an SFF technique. 

Designing Circuit Boards for SFF Integration

Although the objective of contemporary PCB fabrication and SFF manufacturing is the same—a constructed circuit board ready for assembly—the manufacturing processes are quite different. Most boards are built in a fab house by an automated process where multiple boards are made on fixed-size panels. This process consists of many well-defined and organized steps. SFF, on the other hand, is a single-stage, continuous process of adding layers until the board is realized. Just as the processes are different, so are the design files that provide the required information and data for PCB manufacture.  

When designing boards for SFF manufacturing, the adoption of an MCAD format perspective is necessary as the input file for 3D printers is typically a CAD file format such as STL and  IGES.  Therefore, your PCB design software must be capable of ECAD design and MCAD export, as shown below.  

SFF file export options in Allegro.

As shown above, Cadence’s Allegro, the most comprehensive and capable PCB Design and Analysis package in the industry, allows for visual inspection of your design in 3D and export in an additive manufacturing format. Additionally, component editing in 3D is integrated, which provides complete flexibility over the final SFF file format (i.e. PCB without components, or PCBA). 

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.