What Goes Into PCB Manufacturing?
Printed circuit boards (PCBs) are the backbone of modern electronic devices. Several complex processes go into PCB manufacturing, from designing the PCB layout to etching the copper-clad board to drilling holes for components to quality testing the final product.
Effective communication between the OEM and CM is vital to ensure the fabricator completes the assembly to the design’s specifications. This includes collaborating on component selection, design considerations and file formats.
The PCB design aspect of pcb manufacturing involves the blueprints that are created for the circuit board. This process includes comprehending the electrical considerations, deploying the schematic capture tool to develop the PCB layout and generating the layout or design files. The layout files include the component placement file and the routing traces file. The component placement file contains the position and type of each part. The routing traces file contains a schematic of the circuit board and indicates where each trace will connect to other traces. It also identifies the corresponding pins, the signal names and ratings, and the manufacturer parts number. The layout should follow the fabricator’s design rules and constraints, such as minimum trace width and via sizes.
When the layout is complete, it must be verified by a PCB engineer. This step is crucial in ensuring that the final product meets all of the necessary design requirements. It also ensures that the components fit properly and that the bare circuit board meets all of the fabrication criteria.
The actual PCB fabrication process begins when the design is printed onto a piece of laminate material that functions as the base of the structure. Then copper is pre-bonded to the laminate and etched away to reveal the earlier discussed design blueprint. A photo-sensitive film that is made from pcb manufacturing photo-reactive chemicals that harden when exposed to ultraviolet light (the resist) covers the copper layer and laminate panel. Holes are drilled into the resist and laminate to help with alignment.
Printed circuit boards come in various sizes and levels of sophistication. They are the essential components in most electronic devices. This makes it important to pick the right PCB manufacturer for your project. Choosing the best company to work with means understanding their manufacturing process, types of services offered and more.
The first stage in pcb manufacturing is fabrication, which involves the construction of the board. This step starts after the completion of the design phase and ends with assembly. During the fabrication phase, technicians apply pre-preg to the copper areas on the bare boards. A specialized machine then deposits the metal on the pads, which are covered with green solder mask.
Next, the bare circuit boards undergo a metallurgical process to convert the copper into conductors. The bare circuit boards are then cleaned and prepped for layer alignment and optical inspection. This is when the holes from earlier are used to align the different layers of a PCB. The technician places the layers in a registration hole and uses an optical punch to align them.
The conductive paths on the PCB are then etched to create the desired shapes PCB Manufacturing Supplier and sizes for connecting all the components. The etching process also includes adding the copper traces and insulating areas to the circuit board. These steps help in ensuring that the circuit board is complete, and that all nets and traces are properly routed.
The assembly aspect of PCB manufacturing entails assembling and fixing components onto the printed circuit board. This step is crucial to ensuring that the board does what it’s meant to do. Moreover, it’s essential for a top-notch ECM (electronic contract manufacturer) to be able to carry out this task quickly and efficiently.
The next step involves preparing the etched copper plate for assembly by applying solder paste on select areas of the circuit board. The solder paste serves as an adhesive for the unique components on the PCB and helps to bind them into place. This is followed by the placement of solder balls on each element. After the component is firmly set, it goes through a heating process to solidify everything in place.
This phase also requires the technician to clean the printed circuit board from any speck of dirt that may have crept into its layers. Then the stack is taken to a laminating press that uses both heat and pressure to fuse the layers of the PCB together.
Once the layer alignment is complete, the technologist takes the stacked laminated boards through an optical punch. This specialized machine drives a pin through the registration holes to align the inner and outer layers of the PCB. This step is necessary to ensure that the layers come out without any defects, as the defect-free layers will become the core of the finished product.
PCB testing is a crucial aspect of the manufacturing process. It can prevent faulty components from being used in your finished product, which would result in costly failures and recalls. Moreover, it ensures that your PCB meets the necessary performance specifications. This is a requirement for high-quality products. NTS offers comprehensive PCB testing for both bare boards and completed assemblies. These tests include peel tests, solder pot tests, and float tests.
During the testing phase, a machine performs an automated optical inspection to check for any defects in the layers of the board. This is important because once the layers are bonded together, any errors can’t be corrected. The AOI machine compares the PCB with the Extended Gerber design, which serves as the manufacturer’s model. Once the AOI machine finds no defects, the board is ready for assembly.
The most popular type of PCBA testing is in-circuit test (ICT), also known as bed of nails testing. During this process, electrical probes send currents through pre-determined design test points. This helps detect shorts and open circuits, including missing parts and incorrect placement of diodes and transistors. For larger or repeat batches, customized test jigs can be made to perform ICT more quickly and accurately.