A Brief Guide to PCB Manufacturing Process

 

Printed circuit boards or PCBs are the backbone of nearly all computational electronics and can be single, double, or multilayered. A complex system of copper pathways directs the current around the PCB surface.

Designing

Various designer software is used to design the blueprint for a PCB to fulfill all the outlined requirements. The design is rigorously checked for any flaws or potential errors. Once the design gets approved, it's exported in a format its manufacturer supports.

Printing Process

Special printers known as Plotters are used to create photo films of the PCBs. Plotters produce detailed PCB design films owning to their incredibly meticulous printing technology. The final product resembles a photo negative on a plastic sheet in black ink, wherein the clear area denotes the non-conductive regions of the PCB. Each solder mask layer and PCB gets its black and clear film sheet. Registration holes are punched through all layers to align multiple films for multi-layer PCBs.

Printing the Interior Copper layers

The previous step mapped the copper path in the film creation process. Now it's time to create the actual PCB. A laminate board forms the basic structure of the PCB. It receives copper and provides a dust-resistant and robust base for the PCB. Moreover, a decontaminated environment is maintained as cleanliness matters in PCB construction. Next, the laminate panel is covered by a photo resist, a photo-sensitive film layer. The photo resist layer's photo-reactive chemicals harden upon exposure to UV light. Finally, the board is washed off any unhardened photo resist with an alkaline solution.

Unwanted Copper Removed

The board is exposed to a more potent chemical etching process that removes away the excess copper. Then, after another set of solvent wash, the board shines with only the required copper substrate for the PCB.

Inspection

All the layers are aligned and punched to ensure a proper line-up. Then, an automatic optical inspection is performed to eliminate any defects. After the assessment, the board moves to the final PCB production stage.

Layer-up, Bonding, and Drilling

All the separate layers come together and join to form a single PCB. Everything is tightly placed to prevent any alignment issues. The bonding then takes place on a heavy steel table. Finally, precision drill holes are bored into the stack board.

Plating and Final Etching

The panel is electro-plated with a thin layer of copper. A round of final etching gets rid of any extra unwanted copper foil from the board.

Solder Mask and Surface Finish

Solder mask is applied to both sides of PCB. The board is plated with gold or silver to add extra solder-ability.

Final Tests

Electrical tests are performed as part of the final procedure, and various processes confirm the PCB's original design, requirement, and functionality.