Content:

1. PCB Design and File Preparation
2. Printing the PCB Design (Photolithography)
3. Etching the Unwanted Copper
4. Drilling Holes (Mechanical and Laser Drilling)
5. Plating and Copper Deposition
6. Applying the Solder Mask
7. Silkscreen Printing (Component Markings)
8. Electrical Testing and Quality Control
9. Final Fabrication Steps

1. PCB Design and File Preparation

Before fabrication begins, the PCB must be designed using Electronic Design Automation (EDA) software like Altium Designer, KiCad, or Eagle. The design includes:

• Schematic Capture – Defining the electrical connections.

• PCB Layout – Placing components and routing traces.

• Design Rule Check (DRC) – Ensuring manufacturability.

Once finalized, the design is exported as Gerber files (for layers, solder mask, silkscreen) and a drill file(for holes and vias).

2. Printing the PCB Design (Photolithography)

The Gerber files guide the fabrication process:

1. Copper Clad Laminate Preparation – A substrate (usually FR-4) is coated with copper.

2. Applying Photoresist – A light-sensitive chemical is applied to the copper.

3. UV Exposure – The PCB design is printed onto a film and exposed to UV light, hardening the photoresist where copper should remain.

4. Developing the Board – Unhardened photoresist is washed away, leaving the desired copper pattern.

3. Etching the Unwanted Copper

The board undergoes chemical etching (using ferric chloride or ammonium persulfate) to remove excess copper, leaving only the desired conductive traces.

4. Drilling Holes (Mechanical and Laser Drilling)

Precision drilling creates holes for:

• Through-hole components (leads and pins)

• Vias (conductive pathways between layers)

• Mounting holes

High-density PCBs may use laser drilling for microvias.

5. Plating and Copper Deposition

To ensure conductivity in holes and vias:

1. Electroless Copper Deposition – A thin copper layer is chemically deposited inside holes.

2. Electroplating – Additional copper is electroplated to strengthen connections.

3. Surface Finish Application – Options include:

   • HASL (Hot Air Solder Leveling) – Tin-lead coating

   • ENIG (Electroless Nickel Immersion Gold) – Corrosion-resistant gold layer

   • OSP (Organic Solderability Preservative) – Protects copper until soldering

6. Applying the Solder Mask

A solder mask (usually green, but available in other colors) is applied to:

• Protect copper traces from oxidation

• Prevent solder bridges between pads

• Provide insulation

UV exposure and development define where solder mask remains.

7. Silkscreen Printing (Component Markings)

The silkscreen layer adds:

• Component labels (R1, C2, etc.)

• Polarity indicators

• Company logos and certifications

This is typically done using inkjet or screen printing.

8. Electrical Testing and Quality Control

Before shipment, PCBs undergo testing:

• Automated Optical Inspection (AOI) – Checks for defects like shorts or misalignments.

• Electrical Testing (Flying Probe or Bed of Nails) – Verifies continuity and isolation.

• Impedance Testing (for high-speed PCBs).

9. Final Fabrication Steps

• Routing/Scoring – Individual PCBs are cut from the panel.

• Bevelling Edges (for edge connectors).

• Final Inspection & Packaging – Boards are cleaned and shipped.

Conclusion

PCB fabrication is a precise and intricate process requiring advanced machinery and strict quality control. Understanding each step helps engineers design better boards and troubleshoot manufacturing issues.

Whether you’re prototyping or mass-producing, choosing the right PCB manufacturer ensures reliability and performance in your electronic devices.

Would you like a deeper dive into any specific step? Let us know in the comments!