Since the 1950s, printed circuit boards (PCBs) have been developing. In the past six decades, there have been continuing changes in PCB manufacturing and technologies. Significant changes in PCB fabrication include the ongoing shrinking of component parts, use of double-sided boards, development of SMT or surface mount technology, and the implementation of guidelines for PCBs.
When it comes to the use of printed circuit board (PCB), things are different today than in the past because almost every electronic device is integrated with a PCB. From simple consumer electronics that we see every day to personal computers, automobile, and aerospace, name it and a PCB is there.
As a PCB manufacturer, our designers here at pcbnet maximize the potential of a PCB by increasing the performance and maximizing the space of the board. Our experts provide consultation to make sure that we properly execute the design of your PCB without delays.
Steps in PCB Fabrication
The fabrication of PCBs involves several steps. This process primarily uses two types of software – Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM). We use CAD to design the electronic sketch of the circuit that we are going to produce. When we have produced the design, our skilled engineers use CAM to manufacture the prototype of the PCBs.
1. After achieving the PCB prototype design, we choose the material that we will use on the boards. There are various kinds of materials available including Polyimide, Bakelite, Arlon, Ceramic, Alumina, etc.
2. Upon selecting the material, we group the PCBs into a panel or a larger board for bulk printing. A panel may have a single design, but we may mix multiple designs on a single panel. The two types of panels are bare board manufacturing panels and assembly panels (also called arrays).
3. The next step in PCB fabrication is to pattern the copper onto the entire board. When the panel is ready, we replicate the pattern in the CAM software on a protective mask. Later on, the etching process will remove the excess copper from the edges of the board. The different methods of copper patterning are photoengraving, PCB milling, silk screening and laser resist ablation. The patterning method that we use varies depending on the number of PCBs that we need to manufacture and the necessary resolution of the PCBs. We can place the copper using one of these processes:
- Subtractive – the board is entirely coated with copper and then we strip the excess to create the desired pattern.
- Additive – we use a complex process of electroplating the pattern onto a bare substrate. This method of placing copper in PCB fabrication uses less material and produces less waste.
- Semi-additive – this is the most common process, wherein the board already has a thin layer of copper. We apply a reverse mask that displays the parts of the substrate that would become the traces.
4. We use a lamination process to produce separated layers on the PCB. Then, we drill small holes on the board using tungsten-carbide drill bits, which are especially designed to make sure that they do not tear the traces. We also use a laser as an alternative to drilling to create small “vias” (vertical interconnect access – holes that connect board layers).
5. We will then plate the PCBs with solder, gold, or tin over nickel to create a resistant surface for etching. After etching the PCBs and rinsing with water, we apply the solder mask and coat any exposed copper with solder, gold or nickel, or other anti-corrosion coating. Before we add the components, we test the boards to ensure proper connectivity. After validating the board, we assemble the components to create a functional printed circuit assembly (PCA).
6. The last step in PCB fabrication is protection and packaging. PCBs that will be used for extreme conditions often have a conformal coating. This coat prevents corrosion and current leaks or short circuits caused by condensation.