In this article, we will cover the topic of PCB design, including:
- Board materials to use for Printed Circuit Board design
- Layers of a PCB
- Copper traces of Printed Circuit Board
- Vias for the PCB design and layout
- Other considerations for PCB design and layout
- Other concepts to explore in PCB design
Board Materials for Printed Circuit Board Design
Before starting the design process, it’s important to understand the materials that go into a PCB. At the most basic level, the base of the PCB is made of a solid, non-conductive material that is laminated with a copper (or other metal) sheet, creating the conductive surface. The most common base material is a type of glass-reinforced epoxy known as FR-4, as it is flame-resistant, cheap, and has low conductivity. For higher performance circuits, other materials such as ceramic or PTFE with various fillers can be used.
Layers of a PCB
The simplest and cheapest PCBs are single-sided boards, which only consist of the base material with a single sheet of metal on top. Single-sided boards are easy to work with, but can be challenging when it comes to laying out the PCB. Double-sided PCBs are more commonly used as they allow for more complex designs without the need for external jumpers. More complex designs may require additional layers, but for most users, two layers are sufficient.
Copper Traces of Printed Circuit Board
The copper traces on a PCB are a crucial part of the design and it’s important to understand their role and limitations. The traces are created by removing copper from the solid sheet on top of the base material. This means that the traces are actually thin layers of copper, which imposes size constraints on the design.
Vias for the PCB Design and Layout
Vias are used in multi-layer boards to electrically connect one layer to another. There are three types of vias:
- Through Hole: the most common type of via, a hole is drilled through the entire board and electroplated to make it conductive.
- Blind via: used in designs with more than two layers to connect a surface layer to an internal layer without going all the way through.
- Buried Via: similar to a blind via, but used only to connect internal layers.
Other Considerations for PCB Design and Layout
After discussing the basic components of a PCB, there are still some other concepts to consider.
- Solder Mask: this is a layer applied to the board after manufacturing to keep solder paste from spreading, and also gives the board a green appearance.
- Fiducials: special markings on the board used by automated assembly machines to calibrate themselves.
- Silkscreen: another layer added after fabrication, used for visual cues, documentation, component placement identification, or branding.
- Copper Fill: a decision to use a ground/power plane in the design can suppress noise, dissipate heat, or because it is a common practice.
In conclusion, understanding the basics of PCB design and layout will allow you to make your own working design. By exploring these concepts, you will have a more efficient design process and an error-free PCB.