How PCB Manufacturing Works

How PCB Manufacturing Works

At this point, the bare board fabrication files make their way to a fab, or “board house.” A special kind of printer called a plotter prints the PCB plans on transparent sheets. The plan’s “film” contains clear and black ink; the area printed with clear ink represents conductive paths, and the areas printed with black are where copper will be removed.

The Design Process

The design process involves the creation of a blueprint or schematic that captures the net connectivity of all the components on the board. This is typically completed through electronic computer-aided design (EDA) software.

After the initial design is complete, the resulting output files are forwarded to a PCB manufacturer to create a physical circuit board that can be soldered and assembled. During this stage, it is common for multiple design reviews to be performed by the designer in order to ensure that all functional requirements are met. In addition, a number of DFM checks must be run to ensure that the design is manufacturable and will not cause issues when it is being fabricated and assembled.

Once the design is ready, the layers are stacked together into a PCB “sandwich.” The layers are then bonded together with a layer of prepreg that is inserted between each pair of layers. Then, the panels are scanned by a machine that electronically compares the digital image with the original Gerber file to ensure that there are no errors.

Once the boards have been inspected, they are finished and then packaged for delivery to customers. The finishing process usually includes some type of protective coating, such as epoxy resin or solderable copper etch. This coating will help protect the surface of the board from damage during transportation and storage.

The Fabrication Process

The PCB fabrication process converts the design output files (Gerbers and netlist) into a physical circuit board on which components can be soldered. This process is critical for the quality of your final product.

The first step is to create films that map out a figure of copper paths on the substrate material—typically epoxy resin and pcb manufacturing glass fiber or, as it’s known in the industry, laminate. Laminate is the ideal body for receiving the copper that structures the PCB. It’s a dust-resistant and sturdy starting point, as well as a foundation that supports the metal traces and pads that carry electrical signals between layers of the board.

Once the film is in place, the fabricator essentially sandwiches it between aluminum press plates, and then adds copper foil—either as a layer of foil or as a full-on copper coating. The copper carries signals throughout the board, just as your nervous system carries signals between your brain and your muscles. It also carries conductive power to and from components, so it needs to be tightly controlled for proper thickness and copper weight, and for consistent layer to layer alignment.

The next steps include etching the copper and tin plating, and then removing it with chemicals to expose the copper that will form the pads and signal traces of the finished board. The etched copper is then coated with a solder mask to protect it from contamination and give most PCBs their green color. This insulating surface is essential to preventing unintentional shorts between copper traces.

The Assembly Process

Once the bare PCB has been fabricated, it is ready to go through the assembly process. The first step is to paste the solder on the pads that will hold the components. This is done with a stainless steel stencil and solder paste, which is a viscous material that contains microscopic metal balls and a special substance called flux.

The traces are then insulated with the solder mask, which can be green, blue or red in color and is used to prevent short circuits between the copper traces and the components. The copper traces are PCB Manufacturing Supplier the lines that carry signals from one point to another on the circuit board and can be made thin or thick depending upon the type of signal they will be carrying.

Next, the bare circuit boards are sent through an SMT machine and a blade that carries the solder paste is used to apply it on the pad locations where the components will be placed. This is a fast and accurate method of applying the solder paste, and it ensures that the solder is applied to all the required locations.

After the soldering is complete, the assembled boards are inspected using an automated optical inspection (AOI) system that uses high-resolution cameras at various angles to inspect for assembly defects such as component placement and solder joint quality. This helps reduce the cost of producing defective circuit boards that need to be reworked or scrapped.

The Testing Process

Once designers complete their work and forward PCB files to the Fab House, they run Design for Manufacture (DFM) checks. This helps avoid major issues from occurring during production and saves time down the line. During fabrication, bare board electrical tests can also help prevent costly mistakes.

Manufacturers use a special printer known as a plotter to create photo films of the PCB. These images are incredibly detailed, and the plotter uses laser technology to provide a precise film image of each PCB layer. This enables manufacturers to ensure that the PCBs match the original blueprint and are free of errors such as shorts and opens.

The bare boards then undergo continuity testing with automated equipment such as a bed of nails test fixture or flying probe system. These tests check for any unintentional shorts between conductive copper traces. Once the bare boards pass continuity tests, they are sent to the contract manufacturer for component assembly.

PCBs that go through rigorous testing typically have fewer defects and meet performance standards. This results in fewer returned products, which can save companies money on refunds and handling fees. It can also boost a company’s reputation in the marketplace. It’s essential to choose a PCB manufacturer who can offer high-quality, consistent production with a focus on quality at each step of the process.