Printed circuit board (PCB) design is a complex process involving many steps like schematic capture, board layout, DFM analysis, prototype fabrication and assembly. Estimating an accurate PCB design cost is important for budgeting any new electronics hardware project. This article will explore the key factors that contribute to overall PCB design costs.

Types of PCB design costs

The main components of PCB design costs are:

Engineering costs

• Schematic design
• PCB layout
• Simulation and analysis
• Component selection
• Design reviews and documentation

Prototype fabrication costs

• Board materials
• Number of layers
• Board size
• Line width and spacing
• Special processes like impedance control
• Testing
• Shipping

Assembly costs

• SMT programming
• Component cost BOM
• Placement and assembly
• Test and inspection

Tool costs

• EDA software licenses
• Library costs

Other costs

• Communications like conferences calls
• Travel and expenses
• Project management

Key factors impacting PCB design cost

Below are some of the main considerations that affect overall cost:

1. Complexity

More complex boards take longer to design and cost more. Factors adding complexity:

• Component density and pin count
• Number of unique parts and BOM line items
• High speed signals requiring impedance control
• Small board size relative to complexity
• Multiple voltages and power domains
• Layer count
• Mixed-signal content – analog and digital

2. Design quality

Higher design quality results in fewer spins and reduces overall cost. Parameters indicating quality:

• Schematic completeness and consistency
• Layout precision and manufacturability
• DFM analysis like thermal, signal integrity
• Test point inclusion
• Documentation

3. Prototypes and spins

Multiple prototype iterations add cost but reduce long term risk. Consider:

• Number of prototype builds
• Quantity per build
• Design or fab driven spins

4. Certifications

Certification requirements like UL, CE increase design time and prototype costs.

5. Volume

Amortize NRE costs over total production volume. High volume reduces per unit cost.

6. Schedule

Faster time to market has higher engineering costs for resources and tools.

7. Support

Post design support like fab liaisoning, assembly support, DFM review adds cost.

8. Team location

Labor rates vary based on geographic location.

PCB design cost estimation methods

Below are some methods to estimate PCB design costs:

1. Historical data

Leverage costs and metrics from similar past projects of known complexity and scope. Adjust to account for differences.

2. Vendor quote

Get budgetary quotes from vendors outlining their cost structure. Compare multiple vendors.

3. Estimation by hour

Estimate hours needed for each task and multiply by hourly rate based on complexity.

4. Cost per component

Estimate cost based on cents per component placed, adjusted for complexity.

5. Cost by board size

Estimate based on cost per square inches of board area. Adjust for layer count, density, complexity.

6. Cost by design phase

Allocate percentage of total cost to design phases – schematic, layout, prototyping etc based on project scope.

Cost driving PCB attributes

Below are some PCB characteristics that drive fabrication and assembly costs higher:

Layers

Board size

• Minimum charges apply for small boards
• Each additional square inch adds cost

Fine features

• Tighter line width and spacing
• Smaller vias
• High layer to layer alignment

Materials

• Standard FR4 cheaper than high frequency materials
• Exotic materials like ceramic, Teflon costly
• Thicker boards more expensive

Finishes and coatings

• Immersion silver, gold, ENIG cost more than HASL
• Conformal coatings add cost

High density

• More components per area add complexity
• 0402 vs 0603 vs 0805 size components
• BGAs vs QFNs vs 01005 passives

Impedance control

• Tight impedance tolerance layers like +/- 5% add cost

Testing

• Test point access required
• ICT, bare board testing
• Flying probe, boundary scan techniques

Fab and assembly cost drivers

In addition to the PCB, fabrication and assembly processes impact cost:

Example cost calculation

Below is an example cost estimate for a hypothetical medium complexity PCB design:

This provides an initial cost estimate that can be refined as details become clearer. Quote must be obtained from the fabrication shop and assembler for final pricing.

Conclusion

Estimating PCB design costs requires an analysis of the various cost factors based on design complexity, schedule, quality and prototype requirements. Allocating cost by typical percentages for each design phase also provides good budgetary guidance. The cost drivers outlined here help identify areas that can be optimized to reduce overall PCB cost and development risk.

Frequently Asked Questions

Q1: What is the typical cost per square inch for 2 layer PCB fabrication?

For low to medium complexity 2 layer boards, typical cost per square inch is around $2 to $5. High complexity boards can be $6 to $10.

Q2: How can PCB design costs be reduced?

Cost reduction approaches include:

• Simplify schematic and layout as much as possible
• Use fewer layers
• Reduce board size
• Standardize on component packages and footprints
• Reuse proven schematic blocks and layout patterns
• Select standard materials and finish
• Build sufficient DFM review time

Q3: Does PCB assembly cost more for BGA packages versus QFPs?

Yes, boards with many BGA packages often cost more to assemble than QFPs due to:

• More expensive BGA inspection
• Precise solder paste printing
• Tighter component placement tolerances
• Error-prone rework if needed

Q4: How much does fabrication cost reduce at higher volumes?

For volumes above 10,000 pieces, fabrication cost can decrease by 25% to 50% compared to low volume prototype pricing for the same PCB design.

Q5: Does prototyping PCBs in Asia reduce cost compared to North America?

Yes, typically assembly costs in Asia are 30-50% cheaper than North American vendors for low to medium volume batches. So prototypes assembled in Asia can reduce cost.