A PCB is a type of printed circuit board, which allows electronic signals and power to be routed between physical devices. A typical PCB consists of multiple layers with copper traces that connect different points on the board to each other.
The first step in fabricating a PCB is to create a schematic of the circuit you want to build. You can do this using a circuit design software program like KiCad or Eagle.
Schematics are important because they allow you to understand what each component is supposed to do and how they should be connected. They also help you visualize the layout of your PCB and how it will be fabricated in production.
Creating the circuit diagram is a simple task that you can do manually, but it’s not without its pitfalls. For example, if you haven’t done it before, you may have a tendency to make some design choices that don’t work out in the end.
In addition, you can’t make any changes to your schematic until it has been approved by the manufacturer that you are working with. This is an essential step because it’s the only way you can be sure that you won’t end up with a circuit board that doesn’t work right.
Another important thing to remember when designing your circuit is that the manufacturing specifications you specify for your PCB will have a large impact on how your circuit works. For instance, a board that is not built to meet the reliability requirements of your application could result in the failure of your device.
This is why it’s crucial that you consider the fabrication specification of your PCB early on in the design process. By doing this, you can avoid costly issues down the road when it comes time to order your boards and get them manufactured.
Developing the PCB Fabrication Plan
After the design has been approved, the PCB’s components will need to be placed on the circuit board and soldered. The placement of components requires careful attention to detail in order to ensure that each component is positioned properly on the board.
Once the components have been placed, the board will need to be reflow soldered in order to complete the assembly. The reflow process heats up the pads on the board, which causes them to melt and create electrical connections between each pad and the component it is inserted into.
Next, the PCB will need to be etched. Etching is a chemical processing method that removes unwanted copper from the surface of the PCB. The unwanted copper is essentially anything that is not part of the circuit pattern on the board.
During the etching process, the unwanted copper is dissolved in a solution of chemicals called a chemical bath. The amount of copper that is etched depends on the rate of movement of the board and the spray of chemicals used in the process.
The unhardened photoresist is then removed from the PCB with an alkaline solution, leaving the desired copper fully protected under the hardened resist. This preparation will protect the copper until the final AOI (Automated Optical Inspection) and soldering stages, when more powerful chemical solutions are used to eat away at the excess copper.