Printed circuit boards (PCBs) are one of the most important components of electronic devices. Without these, your electronic device will not work. However, let us tell you this – before they become functional, these PCBs undergo series of processes. These processes include the designing of the circuit connection, manufacturing of the board, and mounting of the electrical components.
Designing the PCBs is an intricate process. In this process, the designing team has to consider circuit connections, substrates standards, and assembly methods. The designing team uses software specifically used for printed circuit boards.
There are software offered in the market and has different features depending on specific needs for designing. Most PCB manufacturing companies use industrial, expensive, Windows-grade design software, which are capable of creating designs of even the most complex PCBs.
As we often say, the design stage is similar to a business plan. The engineering team has to create a design based on the client’s needs and specifications. From there, they have to generate a bill of materials (BOM). The BOM is a summary list of all materials, the dimensions of the electrical components and possible exact substitutes for the components.
After the BOM is generated, the designing team has to provide PCB documentation, which includes the BOM, hardware layout, schematics and assembly instructions.
PCBs come in different colors. They could be green, gold or red. They start as a semi-conductive board called substrates. These substrates also called wafer, come from crystalline materials such as glass-ceramics. For substrates used in PCBs, the materials used are glass fiber reinforced resins.
After the designing process, the substrates are manufactured based on the specifications on the PCB documentation. The board or substrates undergo first a process before it is ready for assembly. A roll of reinforced fiberglass is infused with epoxy resins through spraying or soaking. Then, it passes a roller machine to flatten according to the specific thickness or thinness and remove the excess resins.
When done, the substrates are placed in an oven for semi-curing. The cutting process is next. A machine cuts the substrates into large panels, enough to make a several printed circuit boards. These panels are stacked alternately with copper foil. The stacks of reinforced fiberglass and copper foil are placed into a pressing machine. The pressing machine bonds and compresses the fiberglass and copper foil.
Then, the panels are cut into the desired dimension of the PCBs. After which, these PCBs are ready for printing of the circuit connections. In some cases, these panels undergo plating and etching process first before they are cut into individual boards.
This process is an integral part of a through-hole PCB assembly. However, if the mounting technology is surface mounting, the drilling only involves areas that do not involve electrical components such as places for screws. For through-hole mounting technology, CNC milling machines drill holes into the board panels according to the hardware layout. Plugs are placed on non-conductive holes to prevent the machine from plating them.
Plating Or Printing Process
This process involves the placing of copper plates on the surface of the substrates. The individual plate has the circuit patterns that make the board functional after the assembly process. The panels undergo vacuuming, masking, tin-lead coating, stenciling, and etching process.
The etching process refers to the removal of copper plating that is not essential in the circuitry of the final board. This involves a chemical solution process to establish the circuit patterns. After this process, the boards can be already called printed circuit boards.
After which, the PCBs are placed into the mounting machine for electronic component placement. In this process, the PCBs undergo a series of stages before these can be shipped to the company that needs the PCBs.
Printed circuit boards undergo many processes before end-user can use them in the form of an electronic device. Thanks to technological advancement, a single PCB can be manufactured in a minute or so.