What Does a PCB Manufacturer Do?
PCB manufacturing is a complex process that involves imaging and etching. These two steps transform a computer design blueprint into the physical circuit pattern on the board.
Once the panel is scanned by a machine, its digital image compares to a CAD/CAM file that contains specifications for the desired image. If any discrepancies are found, the panel is rejected.
Design for Manufacturability (DFM)
DFM refers to the product design process that aims to minimize production costs and errors. This involves evaluating the design at all levels—system, sub-system, and component. It also focuses on the availability of materials and manufacturing processes and how they would affect the product’s cost.
It is crucial to conduct DFM evaluations in the early stages of design. This way, engineers have plenty of wiggle room to change the product without paying for costly redesigns. This reduces the number of iterations, which also cuts down on production time and overall product cost.
The DFM process must take into account the expected operating environment of the product. This will help determine the appropriate materials and ensure that all parts comply with industry or company standards.
It’s also important to make it easier for repair technicians to access parts that will likely fail first. This includes ensuring that parts can be easily removed and replaced, such as spark plugs in cars and fan belts on air conditioners. It’s also a good idea to use modular design so that it’s easy to replace only the failed part.
Substrate
A substrate is something that another substance or material can operate on. The word can be used in different ways depending on the niche: in chemistry, a substrate is a material that a reaction takes place on; in biology, it’s the surface on which an organism grows or is attached; and in geology, a substrate is the underlying layer of a habitat.
In PCB manufacturing, the substrate is a piece of laminate that serves as the body for the copper that structures the board. The printed circuit board’s design is first printed on film and then transferred to PCB manufacturer the laminate substrate. The film then gets a coating of copper foil that is pre-bonded to the substrate. Then, a process known as etching is performed to remove the copper from the films, leaving the printed circuit board’s blueprint.
During this step, the copper is plated and finished with gold or silver to protect it from corrosion. It also receives a coating that prevents it from being scratched or damaged during its use. The boards are then packaged and sent to customers.
Layers
A PCB has multiple layers, and it’s important to understand the role they play. Similar to the way an electrician follows rules when running electrical wiring through a house’s walls, each layer is essential for the quality of the final product.
The first layer is the mechanical layer. It defines the outer dimensions, data marks, alignment markings and assembly instructions. This layer is the foundation for all other PCB layers and helps to regulate and locate component placements.
The second layer is the copper layer, which can either be a foil or coating. It is responsible for the transmission of signals between components, much like your nervous system carries information from your brain to your muscles.
The routing layer is a copper layer that is dedicated to interconnecting all the different elements of a PCB. It is found on the upper and lower surfaces, as well as inside the board. It can also be split into power and ground planes, which are compact copper layers that are shorted to a common potential. These layers are crucial for distributing power and reducing electromagnetic interference.
Components
A circuit board requires various components to function properly. The most common is the battery, which provides voltage or charge to the circuit board. Other components include diodes, capacitors, fuses, and resistors. They take or store charge to perform their function, and some, like LEDs, also emit light.
Before a PCB can be fabricated, it must pass a DFM check. This is a design review to ensure that the board will work as intended. During this process, the fabricator can spot issues that might affect performance and advise designers to make changes before production starts.
Once the DFM checks are complete, the design files are forwarded to the manufacturer and used to produce a printed film. The film is then bonded to the substrate material and a copper layer is applied. This layer can be either foil or a LED PCB full-on copper coating, depending on the design. Then, the solder mask is applied and any important information is printed on it (like a serial number). Finally, the board is cured and a surface finish is applied to prevent oxidation.
Inspection
Before the PCB can be deemed fit for use, it must undergo several quality tests and inspections. These steps ensure the resulting product matches the initial blueprint and adheres to industry standards. Some of the most important inspection methods include Visual Inspection (VI) and Automated Optical Inspection (AOI). VI involves human inspectors who look for defects such as solder bridges and component placement errors. AOI uses high-resolution cameras to automatically detect these issues. It can also detect surface-level defects such as holes that don’t match their corresponding pads, missing or reversed components, and bent leads.
These automated systems are useful because they can detect issues quickly and accurately, allowing manufacturers to maintain production efficiency and consistency. However, these systems can be subject to errors, such as false positives and false negatives. These issues may be due to limited imaging resolution or algorithm accuracy. False negatives can allow defective products to reach consumers, which can lead to costly recalls and loss of consumer trust. For this reason, many PCB manufacturers use a combination of manual and automated inspection processes.
