Choosing a Printed Circuit Board Supplier
PCBs are the center of today’s lighter, faster and extra strong electronic gadgets. And the best printed circuit board supplier will be able to handle all your PCB requirements from full turnkey design to PCB manufacturing.
A PCB is usually made from a dielectric composite material like FR-4, which is woven fiberglass cloth impregnated with an epoxy resin. It is often clad with copper, which provides conductivity and heat dissipation.
Printed Circuit Board (PCB) Design
PCBs are laminated structures that feature insulating materials between layers of conductors. They are designed with an artwork pattern of conductive traces, pads and planes that electrically connect components to each other. The conductive features are fixed to the substrate with solder, which is also a strong mechanical adhesive. PCBs are used in everything from medical devices such as pacemakers and CAT scan machines to high-tech electronic equipment like computers, printers and video game consoles.
The first step in designing a printed circuit board is front-end engineering, where electronic design automation (EDA) software is used to translate schematic diagrams into the actual layout of a physical PCB. The layout must include all of the necessary information for the PCB to function as intended and to meet any mechanical requirements like dimensional tolerances. The PCB designer must select the appropriate materials and laminate structure to meet performance requirements. Typical laminates are fiberglass and epoxy resin, although other materials like polyamide and FR-4 may be used.
After the layout is complete the design must be transferred to a PCB fabrication shop. This can be done manually or through the use of a PCB design software program. A legend is then printed on the PCB to identify circuitry connections and other indications that are helpful in assembling, testing, servicing and using the device. The legend is usually printed in one or more colors.
PCB Manufacturing
PCB fabrication involves multiple steps, from schematic capture to a fully functional PCB assembly. During this process, you’ll need to find a partner that offers fast turnaround for your prototype. Moreover, look for one that will work with you to ensure your design meets your needs and budget.
In the first step, the PCB manufacturer starts with a printed blueprint of your project. It then prints this design on a piece of laminate material that serves as the base for your circuit board. A layer of copper is pre-bonded to this laminate, which will eventually become the inner and outer layers of your circuit board. This copper is then etched to reveal the printed design on the laminate.
A technician then looks over the etching printed circuit board supplier to ensure that it matches the blueprints exactly. If there are no errors, it moves on to the next step of the PCB manufacturing process.
A similar procedure applies to the inner layer, but this time the etching is chemically backed with potassium permanganate or plasma etching. This removes all resin and glass fibers to expose the copper layers. Once the etching is complete, a machine performs an automatic optical inspection of the PCB to confirm it has no defects. This is a critical step, as any errors in the inner and outer layers can cause problems like unintentional shorts between nets.
PCB Assembly
Printed circuit boards are crucial in electrical, electronics, and electromechanical devices. They have a variety of functions and undergo rigorous testing and inspections to ensure that they function properly for their intended applications. Several different steps go into PCB design, fabrication, and assembly. This includes generating the Gerber files, ensuring that the manufacturer has all the information it needs to build the PCB, and conducting the necessary tests.
During the PCB layout phase, the designer creates a set of layers for the board that correspond with each component on the board. This includes reference designators, labeling, identifiers, and markings. The layout process also accounts for thermal management. For example, components that generate heat can be positioned near the edge of the board or use thermal vias to disperse the heat. Finally, the layout must account for mechanical constraints, such as a space limit or a mounting constraint.
After the layout passes the DRC, the designer prepares the CAD files for manufacture. This typically involves converting the design files to a Printed Circuit Board Supplier Supplier format the manufacturer accepts (Gerber, IPC-2581, or ODB++).
The next step is panelization. The assembler mounts the components onto panels of PCBs. This saves time by reducing the number of steps needed to complete the job. The assembler then adds solder paste to the panels, places the components on the pads using a pick-and-place machine, and solders them in place. The assembler may use manual soldering, wave soldering, or mixed technology.
PCB Testing
A good PCB manufacturing partner will have a variety of testing and inspection processes in place to catch errors before they can cause production problems or product failure. This can lower customer returns, improve client satisfaction, and ensure the company maintains its EMI/EMC and product safety certifications.
Among the most effective testing procedures is an in-circuit test (ICT) that tests a populated circuit board with electrical probes to check for things like shorts, open ends, and capacitance. It is best performed on a bare board to prevent changes from revisions, and can be done before or after the reflow soldering process.
Other methods include AOI, which uses cameras to scan the board and identify issues with it. This is an efficient visual inspection for PCBs, especially when placed before or after reflow soldering when most defects occur. However, it is not able to access all connections or detect all types of defects.
Lastly, functional testing is a method that simulates the operation of a board, checking digital and analog signals. This can be done before a board is shipped to a customer to make sure it will work as intended. Often, this requires human inspectors that are prone to fatigue, may miss small details and inconsistent determinations.