Our PCB fabrication involves many phases before we ship the circuit boards to the assembly house. Before we talk about the stages involved, we want to reiterate that the fabrication and assembly stages are the two major processes. We perform these processes before PCBs become functional and are ready for shipping to our final consumers. Those consumers are the electronics companies who order from us and one of them might be you. Each process consists of another set of procedures and we will discuss them in this article.
Our process starts with designing your PCB. We create the design through a CAD (Computer Aided Design) system. By the way, we offer it as part of the fabrication contract. If you do not want to avail of this value-added service, you can still send us your design. We check your design’s viability. Before we proceed with the fabrication, we make sure that your design is free of flaws.
We see to it that you describe all the aspects of the fabrication process in the Gerber files you sent us. These descriptions include notations on solder masks and components, the type of assembly method, and the purpose of the PCB, among other essential things that you should describe in your design.
By doing this extra checking procedure, we are helping you eliminate added PCB fabrication costs. When we find an error in your design, we coordinate such to your design team. We do not alter your design without explaining as to why we should change the design schematics. After your approval of the final design, we proceed with the process of raw materials selection.
Here are a few reminders from us:
- Use extended Gerber file format for easy and fast analysis of your design. Besides, this is the standard format of today’s fabrication of PCBs.
- Do not scale your design. Use the 1:1 ratio to avoid errors during the PCB manufacturing.
- Lastly, use uniform units of measurement throughout your design. If you use inches in your Gerber files, do the same with the other file data. Conversion may cause errors while we fabricate your PCBs.
Raw Materials Selection
Now, we move on to PCB fabrication, in which raw materials selection is important. First, we select the substrates. We at pcbnet use fiberglass epoxy resin or the popular FR-4 for the dielectric layers and copper for the conducting layers. The other types of PCB substrates are the phenolic resin, which we use for household electronic devices.
Dielectric materials insulate the copper layers and prevent them from creating short circuits between the electronic components. The copper layers can be either on one side or on both sides of the board, depending on your requirement for PCB.
We use a board with a single-sided copper layer for simple PCBs. For multi-functional devices, we often use a board with double-sided copper layers. Double sided are applicable for surface mounting technology, where both we place components on both sides of the board.
Aside from the substrates, we prepare the electronic components for placement. These components include resistors, transistors, and light emitting diodes, capacitors, and integrated circuits chips. We use these materials in the assembly process.
Making the Substrates
Most often, the substrates are still in their sheet forms. We cut the dielectric materials and copper layers into the specific dimensions described on the design. First, we create a single large board. We feed these sheets into a machine to press them together. After the pressing machine, the boards undergo a curing process to make sure that the substrates can conduct and maintain electrical currents once we place electronic components on individual PCBs.
We cut the large boards into smaller substrates, using the actual dimensions of the PCBs. If the assembly method is through-hole technology, we drill the holes for placing the electronic components. Otherwise, we drill holes for the screws and other non-electronic components.
This is the final phase of PCB fabrication before we transfer the circuit boards to the assembly team. The printing phase is an intricate process of establishing the circuitry of the board. We use etching or embossing method.
The etching method is using chemicals to remove the inessential parts of the circuit board while the embossing method uses the direct printing of the circuitry to the board. The newest technology today is the use of ink jet technology. This technology eliminates the need for solder paste stenciling. As a result, it eliminates a few more errors in the reflow of the solder paste. Incorrect paste stencil leads PCB defects.
The PCB fabrication process is a complex stage wherein creating the right substrates should involve an accurate designing process. The quality of the PCBs depends on the many factors. These factors include error-free design, good fabrication practices, and selection of quality materials. We at pcbnet strive to deliver good output by abiding with the regulations for the proper handling of materials and sticking to the standards.