Have you ever wondered what makes your computer tick? What about your PlayStation, or your television, or literally any piece of technology that requires an input? Look no further than process control boards! It’s hard to believe, but this little baby is the brain of most electronics.
What is it?
Process control boards control the machine’s operation: it receives the data from its sensors, processes them and operates given commands. Kind of like how your brain inputs an action for your arm to pick up your diet soda. Without this component, your electronics won’t work.
Although small, the process of making a PCB is long and intricate. If you’re planning to go through a PCB manufacturer, there are multiple crucial steps to developing the board. These are as follows:
Design
Having the blueprints of your designs for the board is the first steps. You can do this through computer software.
Printing
There are two ways to do this process: by a plotted printer or with the use of laser PCB etching. Laser PCB etching can speed up the process if you’re short on time. Two ink colours are used on the inside layers of the board during printing, clear ink for the non-conductive areas and black ink for the conductive copper traces and circuits.
Creating the Substrate
The substrate is an insulating material that holds the components to the structure. Copper is pre-bonded to both sides of these layers and etched to show the design from the printed films.
The Inner Layers
The inner layer is printed to a laminate. A photosensitive film made from photo-reactive chemicals will harden if exposed to UV light, and holes are drilled into the PCB to help keep the boards aligned while printing.
UV light
This is what hardens the photoresist. The black ink prevents hardening in areas that will be removed in a later process. It is then washed with an alkaline solution to remove any excess.
Removing Excess Copper.
A chemical solution is put on to eat away any remaining copper.
Inspection
Step 7 involves checking for defects after an optical punch machine drills a pin through the holes to keep the board aligned. This is also the point of no return. You can no longer correct errors.
Laminating and Pressing the Layers
The board is laminated by using an epoxy resin (prepreg). Then a layer of substrate goes over the prepreg followed by a copper foil layer and more prepreg resin. Finally, one more copper layer is applied. A press is then used to press the layers together by melting the epoxy; fusing the layers together.
Drilling, Plating and Outer Layer Imagining
Holes are drilled to expose the substrate and the inner panels, which is then plated with a thin copper layer and cleaned. A layer of photoresist is applied to the outer layer before being sent to imaging. UV light hardens the photoresist.
Plating Again and Etching
Another copper layer is applied. After, a chemical solution washes the board to remove any unwanted copper. A tin guard layer is now used to establish the PCB’s connections.
Solder Mask Application
Cleaning needs to be done before the solder mask is applied. This is the green colour you usually see on most motherboards and PCB’s. A UV light is used again to remove any excess solder mask.
Silkscreening, and Final Tests
Silkscreening is an essential step because it prints critical information on the board. After this, the PCB goes through one last coating, a curing process, and final testing to ensure the PCB functions.
