The Importance of Working With a PCB Manufacturer
The inner layer goes through automated optical inspection. This ensures that the layer is taking form just as the design dictates and that it doesn’t have harmful copper remnants from the etching stage that could create erroneous electrical connections resulting in short circuits.
A machine also punches a registration hole in each of the layers so they’ll align correctly during lamination.
Printed Circuit Board Design
In the PCB design phase, engineers create a schematic of the circuit board. They then work with a PCB manufacturer to make sure the fabrication process will meet the original design specifications. It is important for both the OEM and CM to have open communication throughout this phase so that changes can be made quickly.
Printed circuit boards are made from dielectric composite materials. The material is typically epoxy resin bonded to reinforcement such as woven, nonwoven, glass fibers or paper. A filler is often added to increase the dielectric constant and other properties of the substrate.
Rigid PCBs are the most common type of PCB. They are used in applications where space is limited and high-speed signals must be transmitted. Flex PCBs are thinner and more flexible than rigid PCBs. They can fit in smaller spaces and can be bent and twisted without damaging the circuit board.
The first step in the PCB fabrication process is imaging the copper on bare PCBs. Technicians print the design on a plotter printer to create a film. They also print the solder mask for the inner layer on this same film. A machine then creates registration holes that will help line up the films with the rest of the layers.
After the imaged copper is etched, technicians inspect each board for defects. The AOI process ensures that the board meets its design specifications and that printed circuit board manufacturer there are no short circuits. This is a critical quality checkpoint midway through the fabrication process.
Printed Circuit Board Fabrication
Before the advent of the printed circuit board (PCB) as we know it, electronic devices were assembled from a multitude of wires that connected components to one another. While this method allowed signals and power to be routed, it lacked the efficiency of PCBs. In addition, it was difficult to debug and maintain.
The first step of the fabrication process involves exposing the bare copper to a chemical called etching. This removes the unexposed copper, leaving only those areas needed for the electrical pathways of the PCB. Next, technicians wash off the remaining resist using alkaline cleaning solution. This exposes the areas of the PCB to be plated. The bare copper is then coated with a thin layer of solder mask, typically green though other colors are available. The solder mask protects the conductive copper from corrosion, and it helps with defect inspection.
After the solder mask is cured, the board goes through an inspection process known as AOI. This is a critical step in the Printed Circuit Board Manufacturer Supplier PCB fabrication process as it checks for defects such as short circuits, extra copper that hasn’t been removed during etching, or holes that were drilled too shallowly.
Lastly, the bare board is protected with a layer of silk screen material that provides a legend for component reference designators, switch settings, and other indications. The legend is commonly printed with white but can be any color that’s suitable for silkscreen printing.
Printed Circuit Board Assembly
Printed circuit board assembly (PCBA) is the process of attaching components and wiring to a printed circuit board. Printed circuit boards are essential to our world, from tiny household devices to jet planes and substantial military forces. In the past, electrical and electronic components were wired point-to-point on a chassis. These connections were done using wire connector lugs or soldering. Eventually, printed circuit boards were developed to make this process more efficient.
To create a PCB, engineers use ECAD software to design the schematic. This software translates simple diagrams into a series of electronic drawings that identify the connection between different parts. The resulting drawing is then converted into a PCB layout by the engineer, and it is sent to the manufacturer for fabrication.
The next step is to apply the finishing touches to the circuit board. This includes a green solder mask, which protects the copper from oxidation and corrosion. Technicians also apply surface finishes to the circuit board. These finishes are vital to the assembler’s ability to mount component leads, as they make it easier to identify a specific area of the circuit board for mounting.
The last step in the fabrication process is the AOI (automated optical inspection). This is an important step because it prevents defective circuit boards from moving on to the next stages of the manufacturing process. AOI inspects the boards for short circuits, incorrect connections and extra copper that might have been left behind during the etching process.
Printed Circuit Board Testing
Printed circuit boards are the heart of electronic products. As such, they are subjected to numerous tests and inspection processes in order to be fabricated according to the required specifications. Even a slight flaw in the board can cause the entire device to fail. Therefore, proper testing is critical for a successful product.
To start with, the PCB undergoes an inspection process called incoming inspection (ICT). This involves a fixed number of probes that are arranged on a bed of nails and exerts pressure to check the integrity of each solder connection. It is a highly effective method of testing, especially for bigger connections and ball grid arrays (BGAs).
After the inspection is completed, the copper on the bare PCB is covered with photo-resist. This is then exposed to a photographic film or photo-mask that details the pattern of tracks needed on the board. After the resist is dry, a chemical etching process removes all of the copper that is not necessary, leaving only the components and traces.
Before applying the solder mask, the board is cleaned using a solvent to ensure that it is free of ionic contamination. This step is also used to detect defects, such as open or short circuits. After the contaminant is removed, a silkscreen or other fine print is applied to the PCB to indicate a component reference designator or additional board markings. Then, the solder mask is cured by baking it in an oven.