From Design to Production: PCB Manufacturing and Component Assembly

Gerber Files: The Language of Manufacturing

Gerber files are the universal standard format for describing a PCB design to a manufacturer. Each layer of the board is represented by a separate Gerber file containing two-dimensional drawing instructions.

Essential files every manufacturer needs:

F.Cu (front copper layer): Traces and pads on the top side.
B.Cu (back copper layer): Traces on the bottom side.
F.Mask (front solder mask): Defines where copper is exposed for soldering.
B.Mask (back solder mask): Same function for the bottom side.
F.SilkS (front silkscreen): Component names and markings.
B.SilkS (back silkscreen): Bottom side markings.
Edge.Cuts (board outline): The external shape of the board.
Drill File: Locations and sizes of all holes in Excellon format.

Exporting from KiCad:

Open the PCB Editor and select File > Fabrication Outputs > Gerbers.
Choose the output folder and select all required layers.
Click Plot then Generate Drill Files.
Compress all files into a single ZIP file.

Verification before sending: Open the Gerber Viewer in KiCad or use a free tool like gerbv to preview each layer and verify design correctness.

Bill of Materials (BOM) and Pick-and-Place File

In addition to Gerber files, you need two more files if you want assembly service:

Bill of Materials (BOM): A table containing every component on the board with its details:

Reference designator (such as R1, C5, U3)
Value (10k ohm, 100nF, STM32F103)
Footprint (0805, LQFP-48)
Supplier part number (such as LCSC or Mouser number)
Required quantity

Pick-and-Place File (CPL): Specifies the exact position of every SMD component on the board:

X and Y coordinates for each component center
Rotation angle
Side (front or back)

Exporting from KiCad:

BOM: From the Schematic Editor select Tools > Generate BOM.
Pick-and-Place: From the PCB Editor select File > Fabrication Outputs > Component Placement.

Important tip: Verify that every component is available from the supplier before submitting the order. A single missing part can delay the project by weeks.

Choosing a Fab: JLCPCB, PCBWay, and Aisler

Choosing the right manufacturer affects cost, quality, and delivery time:

JLCPCB (China):

The cheapest option: 5 double-sided boards starting at 2 dollars.
Integrated SMD assembly service with LCSC component library.
Manufacturing time: 1-2 business days, shipping: 5-15 days.
Suitable for prototypes and small production runs.

PCBWay (China):

Competitive prices with broader manufacturing options.
Supports flexible PCBs and aluminum boards.
Excellent customer service with manual design review.
Suitable for projects requiring special specifications.

Aisler (Germany):

European manufacturer with fast shipping to Europe and the Middle East.
Simple interface that imports KiCad files directly.
More expensive but faster shipping (3-5 days to Europe).
Suitable when delivery speed matters most.

Selection criteria:

Number of boards needed (prototype vs production)
Available budget
Required delivery time
Assembly service needed

Manufacturing Options: Thickness, Copper, and Color

When ordering board fabrication, you will choose several specifications:

Board thickness:

1.6mm: The most common standard. Suitable for most industrial applications.
0.8mm: For compact boards in tight spaces.
2.0mm: For boards subject to mechanical stress.

Copper layer thickness:

1oz (35um): Sufficient for most applications. Signals and low-power lines.
2oz (70um): For boards carrying high currents. Power and motor traces.

Solder mask color:

Green: The industry standard. Cheapest and best for visual inspection.
Black: Professional appearance but makes solder inspection difficult.
White: Suitable for LED boards.
Blue or red: To distinguish between different board revisions.

Silkscreen color:

White on green: The standard. Best readability and clarity.
Black on white: Also clear.

Surface finish:

HASL (Hot Air Solder Leveling): The cheapest. Suitable for prototypes.
ENIG (Electroless Nickel Immersion Gold): Flat surface excellent for fine-pitch SMD. Slightly more expensive.
Lead-Free HASL: No lead. Meets RoHS requirements.

Component Soldering: Manual vs Machine Assembly

After receiving the boards, you need to mount components on them:

Manual soldering:

Suitable for prototypes and small quantities (1-10 boards).
Requires a good soldering station (such as Hakko FX-888D).
Through-hole components are easy to solder by hand.
SMD components in 0805 package and larger can be soldered with practice.
Fine-pitch components (LQFP, QFN) require experience and solder paste.

Automated assembly service:

Suitable for medium and large quantities (10+ boards).
Manufacturers like JLCPCB offer SMD assembly at low cost.
Requires BOM and Pick-and-Place file in a specific format.
Through-hole components are typically soldered manually even with assembly service.

Solder paste and reflow oven:

A middle ground: apply solder paste using a stencil, place components manually, then use a reflow oven or hot air gun.
Ideal for prototypes with many SMD components.

Practical Example: Ordering a Board From JLCPCB With SMD Assembly

Let us follow a real ordering process:

Step 1: Upload Gerber Files

Go to jlcpcb.com and click Quote Now.
Upload the ZIP file containing the Gerber files.
A 3D preview of the board will appear.

Step 2: Choose Manufacturing Specifications

Number of boards: 5 (the minimum)
Layers: 2
Thickness: 1.6mm
Copper: 1oz
Color: green
Surface finish: HASL Lead-Free

Step 3: Enable Assembly Service

Select SMD Assembly and choose the side, then upload the BOM and Pick-and-Place files in CSV format.
Verify that every component is available in the LCSC library.

Step 4: Review and Confirm

Review each component placement and orientation on the 3D preview, then complete the order and payment.

Approximate cost: 5 boards with basic SMD assembly: 15-30 dollars plus 5-15 dollars for shipping. Delivery time: 7-14 business days including manufacturing and shipping.

Summary

Turning a digital design into a real board is the final and most exciting step in the PCB design journey. Understanding manufacturing files, fabrication options, and choosing the right manufacturer ensures you receive high-quality boards at the best possible price. With this, we have covered the fundamentals of PCB design from the initial idea to the manufactured board.