Printed circuit boards (PCBs) are the foundation of every electronic device, from smart wearables to industrial control systems. But the journey from circuit design to a functional PCB relies heavily on one critical element: PCB fabrication specifications.
In this guide, we break down the essential aspects of PCB fabrication specifications, provide real-world pricing examples, and explain how to avoid common pitfalls—so your next project gets off to a perfect start.
1. Introduction to PCB Fabrication Specifications
What are PCB fabrication specifications?
PCB fabrication specifications are the detailed instructions that define how your PCB should be built. These specs are used by the manufacturer to ensure the final board meets your design, electrical, and mechanical requirements.
A standard fabrication specification typically includes:
- Board size and shape
- Number of layers
- Material type (e.g., FR-4, Rogers)
- Copper thickness
- Minimum trace width and spacing
- Drill hole diameters and tolerances
- Surface finish (e.g., HASL, ENIG)
- Solder mask and silkscreen colors
- Special features (impedance control, blind/buried vias, etc.)
Why are they important in 2025?
With the rapid advancement of IoT, 5G, EVs, and miniaturized electronics, manufacturers must produce high-density, high-performance PCBs. Missing or unclear specifications can cause delays, quality issues, or outright failure in production. Therefore, accurate fabrication specs are more important than ever.
2. Key Components of PCB Fabrication Specifications
Understanding the core elements of PCB fabrication specifications will help ensure your design is built correctly and cost-effectively.
a. Board Dimensions and Shape
- Clearly define the width, height, and edge profiles.
- Standard tolerance is ±0.2mm, but tighter tolerances may increase cost.
- Odd shapes or internal cutouts may require additional tooling.
b. Number of Layers
- 2-layer boards: Ideal for simple designs — cost around $5–$10 per board.
- 4–6 layers: Used for signal routing and power planes — range $15–$50.
- 8+ layers: Advanced applications (e.g., high-speed computing) — can exceed $100.
c. Copper Thickness
- Measured in oz/ft² (1 oz ≈ 35μm).
- Standard: 1 oz (both inner and outer layers).
- Heavy copper: 2–3 oz for high-current or power boards — adds $3–$10 per board.
- Uneven copper distribution can cause warping or etching issues.
d. Stack-up Configuration
- Affects impedance, EMI shielding, and signal quality.
- Always include your desired layer stack-up in the FAB drawing or Gerber notes.
e. Solder Mask and Silkscreen
- Standard color: Green
- Optional colors: Black, white, red, blue — may cost $0.50–$1.00 extra.
- Silkscreen ink must be legible and placed outside of solder pads.
3. PCB Fabrication Specifications for Trace Width, Spacing, and Drill Sizes
One of the most critical aspects of PCB manufacturing is the geometry of your copper features and drilled holes.
a. Minimum Trace Width and Spacing
- Defines the smallest line and gap between copper features.
- Standard for most factories: 6/6 mil (0.152mm)
- HDI/advanced boards: As low as 3/3 mil (0.076mm), but significantly more expensive.
- Tighter spacing increases risk of shorts and requires high-precision etching.
Price impact: Reducing trace/space from 6/6 to 3/3 mil may raise board cost by 20–50% due to precision equipment and quality control.
b. Drill Hole Sizes and Types
- Standard mechanical via: 0.2mm – 0.4mm diameter
- Laser microvia: 0.1mm – 0.15mm
- Tolerances: ±0.05mm is typical
- Blind or buried vias are often used in HDI stack-ups and may double the price.
Example Cost:
- 0.3mm mechanical vias on a 4-layer FR-4 board: $20–$35
- Blind vias and laser drilling: Adds $15–$40 per board depending on layer count
c. Annular Ring and Pad Size
- Ensure pads are large enough to maintain annular rings post-drilling.
- IPC-2221 recommends at least 0.15mm ring width for reliability.
4. Material Selection in PCB Fabrication Specifications
Choosing the right PCB material is crucial:
| Material Type | Common Use Case | Base Price (USD) |
| FR-4 | General purpose | $5–$30 per board |
| Rogers 4350B | RF/microwave | $20–$100+ |
| Aluminum Core | LED, power PCB | $8–$50 |
| Ceramic | High-frequency, thermal | $30–$150+ |
The material’s Tg (glass transition temperature), Td (thermal degradation), and Dk (dielectric constant) must match your application.
5. Surface Finish Options in PCB Fabrication Specifications
Different surface finishes affect solderability, corrosion resistance, and cost:
| Surface Finish | Description | Price Impact |
| HASL | Lead-based or lead-free; low cost | +$0–$0.5 |
| ENIG | Gold layer; excellent flatness | +$1–$2 |
| Immersion Silver | Mid-cost, good signal performance | +$0.5–$1 |
| OSP | Organic, cost-effective | +$0.3–$0.6 |
For BGA or QFN packages, ENIG is highly recommended.
6. Industry Standards in PCB Fabrication Specifications
To ensure consistency and quality, follow IPC standards:
- IPC-6012: Sets performance levels for rigid PCBs
- IPC-A-600: Visual inspection criteria
- Class 2 vs. Class 3: Class 3 is for high-reliability applications (e.g., aerospace, medical)
- RoHS/REACH compliance: Mandatory for EU and eco-focused markets
7. Cost Implications of PCB Fabrication Specifications in 2025
The tighter your specs, the more expensive the board. For example:
- Standard 2-layer FR-4 board, 1 oz copper: $5–$10 per board
- 4-layer HDI board with microvias and ENIG finish: $30–$80 per board
- 6-layer Rogers board with tight tolerances: $80–$150+
Key cost drivers include:
- High layer count
- Tight trace/space (e.g., below 4/4 mil)
- Controlled impedance and HDI stack-ups
- Special materials or finishes
8. How to Communicate PCB Fabrication Specifications to Your Manufacturer
To avoid delays and mistakes:
- Always include a complete Gerber file package (.GBR, .DRL, .GML, .TXT)
- Add a fabrication drawing (FAB) with:
- Stack-up
- Drill table
- Surface finish and material notes
- Use standard file formats like IPC-2581 or ODB++ for advanced control
- Double-check unit settings (mm vs. mil) and layer alignment
9. KingSunPCB’s Standard and Custom PCB Fabrication Specifications
At KingSunPCB, we support both standard and advanced PCB fabrication specifications:
Standard Capabilities:
- 2–8 layers, 1 oz copper
- FR-4 base, HASL/OSP finish
- 6/6 mil trace/space
- 0.3mm mechanical drilling
Custom Services:
- HDI with laser vias
- Controlled impedance
- Rogers/Ceramic substrates
- ENIG, Immersion Silver, and more
Our engineers can help review your specs before production to avoid costly mistakes. Prototype orders start from $5 per board, depending on complexity.
10. Frequently Asked Questions (FAQ) About PCB Fabrication Specifications
Q1: What happens if I don’t specify certain parameters?
A: Your PCB manufacturer may apply generic defaults, which might not suit your application. This can lead to over-etching, poor signal quality, or board failure.
Q2: Can I use 1 oz copper on all layers?
A: Yes, but it’s recommended to use 1 oz on outer layers and 0.5 oz on inner layers to prevent over-press during lamination unless higher current is required.
Q3: Do I need controlled impedance in my fabrication specs?
A: If you’re working with high-speed signals (e.g., USB 3.0, HDMI, DDR), yes. Otherwise, it’s optional.
Q4: How much does a basic prototype with standard specs cost in 2025?
A: For a 2-layer FR-4 board with HASL finish, 1 oz copper, and standard tolerances, expect $5–$8 per board for quantities under 10.
11. Conclusion
The accuracy of your PCB fabrication specifications can make or break your project. From signal integrity to cost control and manufacturability, each detail matters. By understanding the key parameters and their impact, you can design smarter, communicate clearly with your manufacturer, and avoid production issues.
At KingSunPCB, we help engineers and designers—from startups to OEMs—build better boards with clarity and confidence. Whether you’re just starting out or scaling up to volume production, our expert team is here to guide you through your fabrication specs step by step.