PCB Manufacturing Process: A Comprehensive Guide

Definition of PCB

Those little green boards assist in the operation of the electrical equipment. The gadget would not function without them. The PCB links all of the other components inside your electronic gadget, allowing you to use it for its intended purpose.

The term PCB refers to a printed circuit board. It supports and links numerous components in a circuit mechanically and electrically. A flat sheet of insulating material and a layer of thin copper foil are bonded onto a non-conductive substrate in the basic printed circuit board design (usually fiberglass). To link the circuit board components, the PCB circuit board employs conductive paths, tracks, or signal traces carved from copper sheets.

Copper is the preferred conductive material for PCBs. A protective layer known as a solder mask or solder resist is applied to these circuit boards to protect them from short circuits and soldering mistakes. CBS are the building blocks of the majority of modern electronic gadgets. Semiconductors, resistors, capacitors, and diodes are all put on the printed circuit board to interact with one another. The PCB fabrication process may now be automated thanks to advances in technology in recent years. Designing, manufacturing, PCB assembly, and testing are the four steps.

A PCB's manufacturing process is rather extensive, despite its modest size. Multiple processes are necessary for the creation of the board, whether you make it yourself or hire a PCB maker. Let's take a closer look at the PCB manufacturing process because each stage is so important to the overall process.

Design of PCB:

PCB design is often accomplished by utilizing PCB layout software to turn your circuit's schematic model into a PCB layout. There are a lot of great open-source software tools for creating and designing PCB layouts.

The manufacturing process of Printed Circuit Boards

Copper is commonly used in printed circuit boards. Copper is plated on a substrate and sliced away to reveal the board's design, depending on the needs. Because there are several layers, they must be aligned correctly and glued together to ensure a solid fit.

Printed circuit board design

You must have a design for the PCB fabrication before you can start producing it. These plans will serve as the foundation for the procedure. In most cases, computer software is used to finish the design process. The bulk of the details needed for inner and exterior layers may be calculated using a trace width calculator.

The printing should be done

The PCB design is printed using a plotted printer, which is a specific printer. It creates a film that depicts the board's intricacies and layers. On the interior layer of the board, two ink colors will be utilized when printed::

• Clear ink to indicate places that are not conductive
• Black ink show the copper lines and circuitry that are conductive.
• The outside layers have the same colors as the inside levels, but the meaning is flipped.

Substrate should be created

The PCB will begin to take shape at this point. By running the materials through an oven to be semicured, the substrate, which is the insulating substance (epoxy resin and glass fiber) that retains the components on the structure, begins to develop. The pattern from the printed films is etched away after copper is pre-bonded to both sides of the layer.

Inner layers should be printed

The design is printed on a laminate, which serves as the structure's main body. The structure is protected by a photo-sensitive film consisting of photo-reactive compounds that harden when exposed to ultraviolet light (the resist). This will aid in the alignment of the plans and the board's actual print. To aid in the alignment procedure, holes are bored into the PCB.

Ultraviolet Light

The resist and laminate are then exposed to UV light to solidify the photoresist. Copper routes are revealed by the light. The previously applied black ink inhibits hardening in regions that will be removed later. To remove the extra photoresist, the board is washed in an alkaline solution.

Unwanted copper should be removed

It's now time to remove any remaining undesired copper from the board. The undesired copper is eaten away by a chemical solution that is comparable to an alkaline solution. The hardened photoresist is still present.

The inspection should be done

The alignment of the freshly cleaned layers will need to be checked. The holes that were bored previously aid in the alignment of the inner and outer layers. To keep the layers aligned, an optical punch machine drills a pin through the perforations. After the optical punch, the board will be inspected by another machine to guarantee there are no flaws. You will not be able to fix any missing errors from now on.

Layers should be laminated

As the layers are fused, the board will begin to take shape. As the laminating process begins, metal clamps hold the layers together. On the alignment basin, a prepreg (epoxy resin) layer is applied. The prepreg is then covered with a substrate layer, followed by a copper foil layer and additional prepreg resin. Finally, the press plate, which is made of additional copper, is attached.

The layers should be pressed

The layers are then pressed together using a mechanical press. Pins are punched through the layers to keep them aligned and secure; depending on the technology, these pins can be removed. If everything checks out, the PCB will be sent to the laminating press, which will heat and press the layers together. The epoxy melts inside the prepreg, fusing the layers with the pressure.

Drilling Processed

To reveal the substrate and inner panels, holes are bored into the layers using a computer-guided drill. After this procedure, any leftover copper is eliminated.

Preparation for Plating process

The board is now prepared for plating. All of the layers are fused using a chemical solution. The second round of chemicals is used to fully clean the board. These substances also leave a thin copper coating on the panel, which seeps into the drilled holes.

Outer layer imaging

After that, a layer of photoresist is applied to the outer layer, identical to Step 3, before being sent for imaging. The photoresist is hardened by ultraviolet light. Any photoresist that isn't wanted is deleted.

Coating

The screen is coated with a thin copper layer, much like in Step 11. The board is then coated with thin tin protection. The tin is there to prevent the outer layer's copper from being etched away.

Etching

Any undesirable copper behind the resist layer is removed using the same chemical solution as previously. The copper is protected by the tin guard layer. The connections on the PCB were formed in this stage.

The application of the Solder Mask

Before applying the solder mask, make sure all of the panels are clean. With the solder mask film, an epoxy is placed. The solder mask creates a distinctive green hue on a PCB. UV light is used to eliminate any undesirable solder masks, while the desired solder mask is baked onto the board.

Silk-screening

Silkscreening is a crucial stage since it is via this procedure that key information is printed onto the board. After that, the PCB goes through a final coating and curing procedure.

Finishing of the surface

Depending on the requirements, the PCB is plated with a solderable finish, which improves the solder quality and bond.

Performance of tests

A professional will perform an electrical test on the PCB before it is declared complete. This will ensure that the PCB operates properly and that the original blueprint designs are followed.

Final arrangements

Dispose of the etching solution with caution; it is hazardous to fish and other water-based creatures! When you're finished, don't even consider dumping it down the sink; it's ILLEGAL and might damage your pipes. Instead, dilute the etching solution and discard it in a secure location.

A pinch of cotton wool and a few drops of thinner (nail polish remover works great) will remove the toner/ink off the plate, revealing the copper surface. Rinse well and pat dry with a clean cloth or paper towels. Trim to final dimensions and sandpaper the edges.

Conclusion

PCBs are among the most typical items you'll encounter if you're interested in electronics. By removing all of the connecting cables and breadboards, these boards make our life easier. It will shrink the size of your gadget if it is appropriately constructed. A printed circuit board (PCB) uses conductive rails, pads, and other features carved from copper sheets bonded onto a non-conductive substrate to physically support and electrically link electronic components. Copper tracks are pre-designed on a conducting sheet on a printed circuit board. The pre-defined tracks decrease wiring, which reduces the number of failures caused by lost connections. Simply arrange the components on the PCB and solder them in place.