This article is a quick overview of how printed circuit boards (PCBs) are designed. Electronic devices that are used in schools, homes, and industries are usually manufactured with printed circuit boards within them. They are usually made from glass-reinforced durable plastic that has copper tracks instead of wires. The components are fixed through drilled holes.These holes are drilled onto the board, where components are placed and then soldered. The components are linked together using copper tracks, forming a circuit.
The first printed circuit boards were designed manually.
In fact, hobbyists still use a photomask drawn on a clear mylar sheet.The design or diagram will be the base where pin pads will be laid out.Traces will also be made to connect the different pads.Traces are often prepared using self-adhesive tape.This type of design method is not done in large-scale PCB manufacturing anymore.
In large-scale production, PCBs are designed using software.The steps that are followed in designing a printed circuit board are the following:
First, there will be a schematic capture using an electronic design automation device.Next, the card size and the template are decided upon based on the needed circuitry and the case that will be used.Next, the component positions and heat sinks are determined.After that, the layer stack of the PCB is determined, depending on the complexity.Then, line impedance is determined.This is done through dielectric layer thickness and trace-width.Then components are ready to be placed.Signal traces are then routed using electronic design automation tools.Gerber files are then generated, ready for manufacturing.
The printed circuit board manufacturing process also consists of many different steps. First, PCB fabrication data is generated using CAD.The Gerber files are read into the Computer Aided Manufacturing software or CAM.CAM takes care of the input of data, verification, and compensation for deviations in the manufacturing process, panelization, and the output of the digital tools such as copper patterns, legend image, and electrical test files, among many others.
Panelization refers to grouping a number of PCBs for manufacturing into a panel.
A panel is a larger board that usually consists of a single design.There are usually two kinds of panels used in the manufacture of PCBs.The first is called an assembly panel or array and a bare board manufacturing panel.The panel is then broken down into smaller, individual PCBs.They are separated through drilling or doing perforations on the boundaries of individual circuits.Think of this as huge sheets of postage stamps.These days, separating panels are usually done suing laser technology. Boards are laser cut with no contact, which reduces stress on the circuits.
In replicating the pattern in the fabricator’s CAM system, there are several methods used.Silk screen printing is when etch-resistant inks are used to create the protective mask.Photoengraving is when a photoresist mask is added while PCB milling and laser resist ablation are also used.These methods are used depending on the number of boards being produced.
Replicating is easy for single- and double-layered PCBs –
For a multi-layer printed circuit board, it is a bit more challenging because it has trace layers inside.Lamination is when a stack of PCBs are processed in a press, using heat and pressure for a certain period of time.The end-result is an inseparable one-piece material.
The printed circuit board will still go through many other phases in the manufacturing process. The next phase is the actual PCB fabrication process.This process includes sub-processes such as drilling, solder and resist application,plating and coating, legend printing, bare board test, protection, testing and packaging.
These are just some of the general things hobbyists learnabout designing printed circuit boards.Hopefully, this article has helped you in broadening your understanding of PCBs.