Printed Circuit Boards (PCBs) are at the heart of every electronic product. While much focus is placed on performance, thermal management and, increasingly, miniaturisation, a crucial yet often overlooked area is design for manufacturability (DFM). Poor design choices can dramatically increase manufacturing costs and delay production.

This article explores the most common PCB design mistakes that raise production costs and provides top tips on how to avoid them.

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 1. Ignoring manufacturer design guidelines

Every PCB manufacturer provides specific design rules for what they can reliably manufacture. This will include things like minimum trace widths, spacing, via sizes, copper thickness, solder mask clearances, and board outline tolerances.

Why it increases costs:

• Ignoring these rules means manufacturers are forced to use advanced (and expensive) processes so they can move forward with the build.
• Non-compliant designs are often rejected resulting in time-consuming and costly redesigns.
• Ignoring standard tolerances leads to an increased scrap and lower yield ratio.

 What to do:

• Engage with a manufacturer early in the development process and obtain a detailed design rule specification from them.
• Import these rules into your chosen design tool and run automated checks against the specification throughout the design process.

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2. Using fine traces and tight spacing unnecessarily

Overdesigning for density by using excessively narrow trace widths and close spacings can lead to manufacturing difficulties, increase cost and cause signal integrity issues.

Why it increases costs:

• Narrow traces require high-resolution imaging systems, slower etching processes, and higher inspection efforts.
• Defect rates increase due to under-etching (where copper is removed both vertically and laterally) which can lead to short circuits and result in costly rework.
• The cost per panel goes up significantly with tighter geometries.

What to do:

• Use ≥6 mil traces and spacing whenever possible.
• Reserve finer traces for constrained areas like under high-density ball grid arrays (BGAs).
• Use controlled impedance design and simulation to avoid over constraining line widths unnecessarily.

3. Overuse of PCB layers

Whilst more layers will offer an increased number of routing options, it will also increase costs exponentially, especially if used unnecessarily.

‍Why it increases costs:

• Every additional layer adds to material costs and lamination cycles.
• Multilayer boards require precise registration, increasing setup and inspection time.
• Higher risk of delamination or layer misregistration in production.

What to do:

• Prioritise efficient routing and power/ground plane sharing.
• Consider using components with higher pitch or smaller footprints to reduce routing congestion.
• Use 4-layer boards for moderate complexity. Only go to 6, 8, or more layers when required for high-speed, high-pin-count ICs.
• Often, increasing overall board dimensions is more cost effective than adding an additional layer.
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4. Excessive or inappropriate use of vias

Vias are convenient as they solve many routing situations and improve the heat exchange but should be used wisely. Specialised vias (microvias, blind/buried vias) are useful but very expensive to fabricate.

Why it increases costs:

• Blind/buried vias require sequential lamination and drilling, adding multiple fabrication steps.
• Microvias demand laser drilling and higher-end substrate materials.
• Poor via planning can obstruct routing and complicate signal integrity.

What to do:

• Use through-hole vias unless layout constraints demand otherwise.
• Avoid stacking microvias. Staggered configurations are more robust and cost-effective.
• Minimise via-in-pad designs unless for high-speed (radio frequency) RF or BGA fanout; and ensure filled and capped vias are specified.
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5. Designing non-standard board shapes and sizes

Irregular board outlines or shapes, internal cut outs, and uneven edge contours complicate assembly.

Why it increases costs:

• Reduced panel efficiency results in fewer boards per panel.
• Odd shapes often require custom tooling.
• Internal routing (slots, cutouts) adds extra CNC or laser machining time.

What to do:

• Design rectangular or panel-friendly outlines (e.g., multiples of 50mm x 50mm or 100mm x 100mm).
• Use mouse bites or V-scores for breakouts instead of internal slots.
• Minimise the number and complexity of mechanical features unless necessary.

6. Inadequate component placement and spacing

A crowded PCB might look efficient, but it poses numerous issues in assembly and inspection.

Why it increases costs:

• Automated pick-and-place machines need a minimum clearance between parts (often ≥1 mm).
• Solder bridges and tombstoning become more common with poor spacing.
• Inspection (optical and X-ray) becomes less reliable when components are tightly packed or misaligned.

What to do:

• Follow manufacturer guidelines for land pattern recommendations and spacing.
• Maintain minimum spacing of 0.5 - 1.0 mm between SMT components.
• Align polarised components uniformly to assist with visual inspection and reduce placement errors.
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7. Providing an inaccurate or incomplete Bill of Materials (BOM)

Your BOM is not just a parts list, it is your supply chain's blueprint. Errors in the BOM can halt production.

Why it increases costs:

• Ambiguities or missing part numbers delay procurement.
• Substitute components may not fit the PCB footprint, requiring rework or redesign.
• Obsolete or out of stock parts can lead to redesign cycles or long lead times.

What to do:

• Include full part numbers (manufacturer + supplier), values, tolerances, footprints, and packaging types.
• Use BOM verification tools and supplier integration.
• Add alternate part numbers where feasible to ensure sourcing flexibility.
• Where a part is known to be difficult to source, consider using a dual footprint to expand sourcing options.

8. Neglecting design for test (DFT) principles

A design that’s hard to test costs more to validate and diagnose in both production and the field.

Why it increases costs:

• Increases time and complexity for in-circuit and functional testing.
• Limits automation in production testing, requiring costly manual probing.
• Increases field failure rates due to undetected defects during production.

What to do:

• Add test points on key signals, power rails, and clock lines.
• Ensure probe access by maintaining clearance from tall components.
• Use boundary scan (JTAG) where applicable and design with built-in self-test (BIST) features for complex boards.

9. Inadequate thermal and power management

Without proper thermal and power planning, components overheat, fail prematurely, or cause erratic behaviour.

Why it increases costs:

• Hotspots may require active cooling retrofits or more expensive materials.
• Thermal stress can warp the PCB or desolder components.
• Voltage drops on inadequately routed power traces can cause malfunctions.

What to do:

• Use thermal vias, large copper pours, and plane layers to spread heat effectively.
• Perform thermal simulation during design.
• Maintain proper width for power and ground traces.

10. Incomplete or confusing documentation

Even the best design can fail in manufacturing if the supporting documentation is incomplete or ambiguous.

Why it increases costs:

• Delays in clarification increase lead time and labour costs.
• Misinterpretations lead to scrap, rework, or incorrect board builds.
• Missing files can halt production entirely.

What to do:

Ensure you provide the full documentation set:

• ‍Gerber files: One per layer including copper, mask, silkscreen, paste, outline.‍
• Drill files: Excellon format.‍
• Pick-and-place files: For automated assembly.‍
• Assembly drawings: Component orientation, reference designators.‍
• Fabrication drawing: Board stack-up, drill sizes, tolerances, finishes.‍
• BoM: Ensure the BoM is detailed and current.

Designing a PCB is not just about electrical performance, it's also about manufacturability, cost-efficiency, and reliability. The earlier you consider DFM principles in your workflow, the more cost savings and production efficiency you'll realise.

By avoiding these common pitfalls, you can:

• Reduce manufacturing and assembly costs.
• Minimis delays and improve first-pass yield.
• Achieve faster time to market with few revisions.

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Pro tip, treat your manufacturer and assembler as design partners. Involve them early, share your intent, and solicit their feedback during the layout phase, not after the first prototype.