Printed Circuit Boards (PCBs) are the backbone of most electronics and technology nowadays. In the early 1900s, we witnessed the development of the first-ever printed circuit boards (PCBs) that changed how the electrical industry used to work. With this invention, the costs of the circuit board assembly were reduced and simplified significantly. Today, these incredible inventions are the foundation of almost all computational electronics and even simpler devices such as digital clocks, calculators, etc.
The purpose of the PCBs is to provide a route to electrical signals from end to end to electronics, fulfilling the device’s electrical and mechanical circuit needs. As far as the designing and manufacturing of PCBs go, it is quite significant for anyone involved in the electrical industry. Since PCBs are responsible for passing the electricity through the components connected to the board, it must be the best quality.
If you are reading this article, I assume that you want to learn how designing and manufacturing the PCBs go. We have mentioned everything in detail below. If you are intrigued to learn, be sure to check out this article till the end.
A Guide to PCB Manufacturing Process:
Step 1: Creating the Design
First things first, before you start with the manufacturing process, you need to have a design of the board on hand. Get your best designer to work for creating a layout, to begin with. Typically, computer software such as OrCAD, Altium Designer, Pads, KiCad, Eagle, among others, is used to create the design. Be sure to check the details of both the internal and external links before finalizing the design.
Step 2: Printing the Design
Once you have decided on your PCB design, the next step is to print it. For this, manufacturers use a particular type of printer called a plotter. By using this printer, photo films of the PCBs are printed on the circuit boards. Unlike a standard laser jet printer, a highly detailed film of the PCB design is provided using the incredibly precise printing technology of Plotter.
Step 3: Making the Substrate
When the PCB begins to form, the process of making the substrate will start forming as well. The substrate is an insulating material which is responsible for holding the components on the structure. The substrate material (epoxy resin and woven glass fiber) passes through an oven to be semicured. After passing through the oven, the material is cut into large panels. These panels are then stacked in layers, and copper is pre-bonded to both sides. Lastly, the design from the printed films is shown once they are etched away.
Step 4: Inner Layer Printing
Now, the design is printed to the laminate board, which is the substrate material. It acts as a body for receiving the copper that structures the PCB. A photo-sensitive film covers the structure. It will line up the blueprints and the real print of the board. And to support the alignment process, holes are drilled into the PCB.
Step 5: Ultraviolet Light
After the alignment process, the resist and laminate pass through ultraviolet lights to harden the photoresist. Now, to remove the extra photoresist, the board is washed with the alkaline solution.
Step 5: Removing Unwanted Copper
Now, unwanted copper is removed with the help of a chemical solution similar to the alkaline solution. This solution will remove extra copper without harming the hardened photoresist.
Step 6: Optical Inspection
After all the layers are clean and ready, they need to be inspected for alignment. Both the inner and outers layers will be lined up with the help of holes drilled earlier. An optical punch machine drills a pin over the holes to keep layers aligned. After this, the inspection process starts to make sure there are no imperfections.
Step 7: Layer-up and Bond
In this step, the board takes the desired shape. Now, the layers simply require fusion. The outer layer needs to join with the substrate via layer-up and bonding. After this 2-step process, the layers will be sandwiched together.
Step 8: Drilling
Finally, holes are bored into the board using a computer-guided drill to uncover the substrate and inner panels. After this step, the remaining copper will be removed.
Step 9: Plating
After drilling, the board is ready to be plated. With the help of chemical solutions, all the layers will be fused. Next, the board is thoroughly cleaned using another chemical solution. These solutions will also provide a thin copper coating to the panel, settling into the drilled holes.
Step 10: Outer Layer Imaging
Again, a layer of photoresist will be applied to the outside layer before the imaging process. Ultraviolet light will help harden the photoresist, removing the unwanted photoresist.
Step 11: Plating
Just like step 9, we will coat the panel with a thin layer of copper. Then the thin tin guard will be layered to the board to protect the copper of the outside layer.
Step 12: Final Etching
The unwanted copper will again be removed using the same chemical solution used before. At the same time, the tin guard keeps the needed copper protected. This step will create the PCB’s connections.
Step 13: Solder Mask Application
All the panels are cleaned and coated with an epoxy solder mask ink before the solder mask is applied on the board. The solder mask applies the green color, which is the typical color we see on the board. The unwanted solder mask is removed with ultraviolet light.
Step 14: Surface Finish
The PCB is plated with gold or silver to add extra solder-ability to the board, which will increase the bond of the solder.
Step 15: Silkscreening
It is the crucial step because, in this process, critical information is printed on the board. Once it is done, the board will pass through the last coating and curing stage.
Step 16: Electrical Test
As a final step, a technician will perform an electrical test to ensure the board works fine. The test will approve the functionality of the PCB.