Designing for Manufacturability: Tips to Reduce Costs and Improve PCB Reliability

Design for testing oversights can silently triple your PCB manufacturing costs. Even experienced designers frequently encounter hidden flaws that only become apparent during production, consequently leading to expensive revisions, delays and rejected boards. Small mistakes in solder mask definitions, component placement or trace routing significantly impact manufacturability and yield rates. Furthermore, these issues often remain undetected until after you’ve committed to production, when corrections become exponentially more expensive.

Specifically, problems like improper via tenting, non-standard component orientations and excessive blind via usage create manufacturing challenges that manufacturers must address—at your expense. These design oversights not only inflate fabrication costs but also complicate assembly processes, reduce reliability and extend time-to-market. This comprehensive guide examines the most common DFM pitfalls across multiple design areas and demonstrates how proper design verification tools can help you identify these issues before they impact your bottom line.

PCB manufacturing costs can escalate rapidly due to seemingly minor design oversights. While these issues might appear trivial during the design phase, they often lead to expensive rework, production delays, and reliability problems once manufacturing begins.

Solder mask serves as a protective layer that prevents solder bridges between closely spaced pads and tracks, helping avoid costly short circuits. Without proper solder mask definition, achieving high-quality, reliable PCBs becomes exceptionally challenging. For fine-pitch components, the spacing between pads is often too small to allow solder mask dams, making these areas particularly vulnerable.

One critical function of solder mask is preventing solder starvation. When solder mask doesn’t cover tracks attached to copper pads, molten solder can flow down these tracks, depriving the pad of adequate solder and creating unreliable joints. Similarly, uncovered vias near pads can wick away solder, compromising connection integrity.

Best practises dictate that solder mask apertures should be 75 μm larger than the pad on either side (or 150 μm larger than the pad diameter) to prevent solder mask encroachment. Additionally, fabrication drawings should explicitly note that solder mask should not encroach on component pins or pads, whilst allowing manufacturers to modify apertures where necessary.

Padstacks—vertical collections of pads centred on plated through-holes—significantly impact long-term PCB performance and reliability. Common errors in padstack design include improper pad sizes, incorrect clearances, and flawed hole specifications.

Through-hole breakout occurs when pads are too small, lacking sufficient annular ring size to compensate for drill wandering. This results in broken circuits or improper soldering. Conversely, surface mount pads that are too small prevent proper solder fillets, creating weak joints prone to failure, whereas oversized pads cause components to float out of position during reflow.

“Tombstoning” presents another costly issue, occurring when pads of unequal size cause uneven heating. This defect pulls components up from one pad, resembling a tombstone and requiring time-consuming rework.

In high-speed designs, non-functional pads (inner layer pads without connecting traces) can impact signal integrity. Whilst removing these pads increases routing space, selective non-functional pad removal offers a balanced compromise between fabrication and design constraints.

Via tenting—covering vias with a protective layer like solder mask—shields these openings from environmental factors including dust, moisture, and chemicals that cause corrosion or short circuits. This process proves particularly valuable for PCBs exposed to harsh environments or high-speed designs requiring improved signal integrity.

Tenting effectiveness varies with via size, being most reliable for vias with small holes (12 mils or less in diameter). For larger vias, filling and closing typically yields better results. Closely spaced vias increase the risk of solder mask bridging or incomplete coverage, necessitating adherence to IPC guidelines for minimum spacing.

Proper spacing around backdrilled vias demands careful consideration. Insufficient clearance between backdrilled areas and other copper elements creates potential electrical issues, reducing overall PCB reliability. Backdrill spacing checks must verify adequate separation between back drill pins, vias, traces, and shapes to prevent manufacturing defects.

Ignoring Design Rule Checks (DRC) relating to these issues invariably results in costly errors. Even minor spacing violations or incorrect drill sizes can cause manufacturing failures that dramatically increase production costs. Employing robust DFM checks through tools like DesignTrue DFM helps identify missing solder masks and validate critical parameters before production begins.

Component placement decisions directly impact assembly success and manufacturing costs. Even small errors in how parts are positioned and oriented can transform an otherwise well-designed PCB into an expensive manufacturing nightmare. These seemingly minor oversights often remain undetected until the assembly phase, where they create significant production challenges.

Proper component orientation represents a critical aspect of design for testing and efficient manufacturing. Indeed, standardised orientation of similar components simplifies assembly, inspection, and maintenance processes. Most manufacturers recommend organising components in rows and columns (matrix-style), with uniform orientation to streamline assembly by pick-and-place machines.

For integrated circuits, orientation consistency is particularly important. All ICs have a reference pin (pin 1) that should be aligned consistently throughout the board. Nevertheless, power supply components sometimes require unusual orientations—occasionally at non-90-degree angles—to achieve optimal signal and power routing with minimal trace length.

Before finalising component orientation, always:

• Verify manufacturer capabilities for non-standard orientations
• Consider testing access requirements
• Prioritise tight placement for power supply components
• Maintain consistent orientation for passive components where possible

Components placed with incorrect orientation frequently lead to reversed polarity, improper connections, and subsequently, non-functional boards. This oversight requires expensive rework and dramatically reduces production yields.

Automated pick-and-place machines require specific minimum clearances between components for efficient operation. Without proper spacing, manufacturers must resort to manual placement—a substantially more expensive and error-prone process. Generally, designers should maintain at least 40mil spacing between components and 100mil between components and board edges.

For wave soldering, component height sequence becomes crucial. If smaller components are positioned behind taller ones (relative to wave direction), they become “shadowed” during the soldering process, resulting in poor solder joints. Therefore, shorter components should be placed behind taller ones in the wave soldering process flow.

Inadequate clearance between components furthermore creates challenges beyond initial assembly. Repair access becomes practically impossible without sufficient spacing, making future upgrades or repairs extremely difficult and potentially damaging to surrounding components. This limitation significantly increases lifetime maintenance costs and reduces product longevity.

Fiducial marks serve as critical reference points that enable automated assembly equipment to precisely align components. These small copper features (typically circular pads surrounded by a clearance area) act essentially as visual GPS coordinates for optical inspection devices and pick-and-place machines.

Without fiducial marks, modern electronics manufacturing faces substantial challenges. High-resolution cameras in assembly machines scan for these marks to:

• Correct for board misalignment in real-time
• Enable consistent results across multiple boards
• Calculate precise component positions

Skipping or improperly placing fiducial marks invariably leads to component misalignment, increased rework requirements, machine downtime, and higher defect rates. Most designs require at least three fiducial marks, with ample clearance around each to ensure easy recognition by assembly equipment.

Fiducial marks prove especially critical for fine-pitch components, Ball Grid Array (BGA) packages, and high-density boards. They should be free from solder masks and other coatings, with standardised shapes and sizes (typically 1-3mm diameter). For double-sided boards, fiducial marks must appear on both sides to ensure proper alignment when flipping the board during assembly.

Trace routing and via decisions dramatically affect PCB fabrication complexity and costs. Seemingly minor design choices in these areas can lead to expensive manufacturing challenges that multiply your production expenses.

Though blind and buried vias solve complex routing challenges, they considerably increase manufacturing costs. This cost escalation stems from additional processing steps, testing requirements, and specialised equipment needed for their implementation. Manufacturers must drill and plate these structures separately for each layer pair, increasing production time and materials usage.

Blind vias require precise drill depth control—too deep causes signal degradation, whilst too shallow creates improper connections. Moreover, manufacturers must properly plug vias with metal or thermal/electrical epoxy and plate copper over them to prevent internal air bubbles that create voids or pinholes in solder joints.

A common design error involves placing vias directly between surface mount component pads. This practise traps solder flux, potentially causing corrosion problems that remain difficult to inspect once the board is assembled. Furthermore, each via introduces parasitic inductance and capacitance that impacts signal integrity, particularly at high frequencies.

Right-angle PCB traces create multiple manufacturing and performance issues. The outside corner of a 90-degree trace typically etches more narrowly than the standard trace width, occasionally forming inadequately etched areas that may create shorts. These corners also experience higher electric field density compared to other trace angles.

The primary technical issue with right-angle bends involves impedance discontinuity. A 90-degree corner contains excess capacitance (approximately 1.7 fF/mil of line width) that causes signal reflections. For instance, a 20-mil wide trace corner adds approximately 34 fF of excess capacitance.

In high-speed applications, these impedance variations become critical. A 120-mil wide trace with a 90-degree corner shows noticeable signal impact at 5 GHz, with return loss reaching -10 dB at 10 GHz. Consequently, multiple periodic corners can create resonance, showing enhanced return loss and insertion loss dips at specific frequencies.

Non-standard trace dimensions directly increase fabrication costs. Typically, trace widths narrower than 5 mils (0.005″) and spacing closer than 5 mils require tighter PCB tolerances and more expensive equipment for manufacturing and inspection. Similarly, via holes smaller than 8 mils in diameter raise production costs significantly ¹.

For current-carrying traces, appropriate width selection remains crucial—ranging from 0.010″ for 0.3 amps to 0.150″ for 6.0 amps ². Inadequate width selection causes either thermal issues or unnecessary board space utilisation.

High-speed signals demand careful trace design for impedance matching. Different signal types require specific controlled impedance values: USB (90 ohms ±15%), HDMI (95 ohms ±15%), IEEE 1394 (108 ohms ±2%), and Ethernet Cat.5 (100 ohms ±5%). Impedance mismatch produces signal reflections proportional to the difference between unmatched impedances, with larger mismatches creating larger reflections that compromise signal integrity.

Trace spacing equally impacts both cost and performance. Though 0.003″ represents a common minimum spacing, recommended spacing for most trace widths should be at least 0.010″. Higher voltage applications require even greater spacing to prevent electrical arcing and ensure safety.

Thermal management and signal integrity issues frequently lead to PCB yield problems that could easily be prevented. Such oversights not only affect immediate performance but often cause long-term reliability problems that manifest after deployment—precisely when corrections become most expensive.

Inadequate thermal design remains a primary cause of component failure in modern electronics. As miniaturisation and higher power densities become standard, effective heat dissipation grows increasingly critical. Without proper thermal management, components experience degraded performance, reliability issues, and drastically reduced product lifespan.

Thermal vias serve as essential pathways for transferring heat away from surface-mounted components, yet their implementation requires careful consideration. For optimal results, designers should:

• Use multiple small vias (0.2–0.3 mm diameter) beneath high-power components to maximise density ³
• Prefer via filling or via-in-pad structures for better heat transfer
• Connect vias to large ground or power planes that act as heat sinks

In high-power applications, PCB-level solutions alone may prove insufficient. Rather than relying solely on board-level thermal management, external heatsinks and copper heat spreaders become necessary additions.

Ground planes provide critical low-impedance return paths for electrical signals. In reality, current always seeks the path of least impedance back to its source—a fact often overlooked in PCB design. At high frequencies (MHz range and above), return current distribution creates complex patterns beneath signal traces.

Poor grounding remains a significant cause of signal integrity problems and EMC test failures. These issues manifest first as waveform distortion, ground bounce, and increased crosstalk. Splits or holes in ground planes force return current to take detours, expanding loop areas and increasing inductance. These disrupted paths then act like antennas, radiating electromagnetic waves that interfere with both internal circuits and external devices.

Decoupling capacitors stabilise voltage levels between power and ground, yet their effectiveness depends heavily on placement. Above all, these components must be positioned to minimise parasitic inductance, which can negate their benefits entirely ²³.

Contrary to common practise, placing capacitors directly under BGA components isn’t always optimal. Instead, distributing them strategically across the board often yields better results, ensuring accessibility while maintaining performance. Meanwhile, in boards with closely spaced power planes (under 4 mils apart), capacitor location becomes less critical as the planes themselves provide necessary capacitance.

For maximum effectiveness, decoupling capacitors should connect directly to ground and power planes through vias rather than using traces to the IC pins. This approach minimises loop inductance and maintains stable voltage levels even during rapid current transitions.

Modern PCB design tools offer powerful capabilities for identifying and preventing manufacturing issues. Early detection of these flaws can significantly reduce production costs and improve first-pass success rates.

Allegro X provides continuous verification through over 2,000 configurable checks that run while you design, delivering instantaneous visual feedback to eliminate issues before they become costly problems. This approach breaks the traditional find-fix-reiterate cycle, helping designers get their designs right the first time. Currently, these integrated DFM engines enable simple sign-off rather than lengthy revision processes.

The system verifies designs against manufacturer’s rules throughout the PCB layout process, thereby ensuring first-pass manufacturing success. This real-time analysis identifies potential fabrication, assembly, and test issues early, thus avoiding expensive respins and keeping projects on schedule.

Valour NPI incorporates expert knowledge about fabrication and assembly processes, making this information accessible earlier in the design flow. Hence, designers can apply DFM rules prepared by manufacturing experts during layout without requiring process expertise themselves.

The tool validates designs against over 1,000 comprehensive checks spanning various manufacturing technologies, including rigid/flex, flex, and packaging substrates. Apart from analysis, Valour NPI prioritises design-change requirements based on configurable weights assigned to each check.

Constraint Manager functions as a document-based, spreadsheet-like interface allowing designers to view, create, and manage design constraints. In essence, it shifts from query-based rule scoping to applied object type matching, which simplifies constraint rule creation.

The primary advantages include:

• Availability at project level with similar access from both schematic and PCB domains
• Automatic rule priority based on natural hierarchy of design objects
• Unified approach for electrical and physical constraints in one framework

DesignTrue DFM identifies missing masks during library creation or later design stages. In fact, this capability helps detect common DFM mistakes like missing soldermask for surface mount and through-hole pads.

The tool supports various checks throughout different PCB design stages—from footprint creation to post-route cleanup. According to documentation, DesignTrue’s copper spacing checks validate minimum spacing between different objects, whilst copper features checks identify slivers, acid traps, and minimum width issues. The wizard allows engineers to quickly configure fabrication, assembly, and test constraints based on manufacturer requirements, guaranteeing producible, error-free PCBs.

PCB design flaws can silently escalate manufacturing costs, turning otherwise promising projects into expensive nightmares. Throughout this guide, we’ve examined how seemingly minor oversights significantly impact both fabrication and assembly processes. Solder mask deficiencies, incorrect padstack definitions, and improper via tenting represent just the beginning of potential issues that compromise board reliability.

Component placement errors certainly deserve careful attention. Non-standard orientations, insufficient spacing for pick-and-place machines, and missing fiducial marks all complicate assembly and increase costs. Likewise, trace routing decisions involving excessive vias, 90-degree bends, and unoptimised dimensions directly affect manufacturing complexity and yield rates.

Thermal management remains equally critical. Boards without proper thermal relief for heat-generating components face shortened lifespans and performance degradation. Additionally, inadequate ground planes and poorly placed decoupling capacitors create signal integrity problems that might only become apparent after deployment—precisely when fixes become most expensive.

The good news? Modern DFM tools offer powerful solutions. Real-time checks in systems like Allegro X, comprehensive rule setup with Valour NPI, and validation through DesignTrue DFM help identify these issues before production begins. Consequently, designers who implement rigorous DFM verification early can expect higher first-pass yields and dramatically reduced manufacturing costs.

PCB design requires balancing technical requirements with manufacturing practicalities. The most elegant electrical design still fails if it cannot be reliably manufactured. Therefore, building DFM considerations into your workflow from the beginning—rather than treating them as an afterthought—stands as the most effective strategy to prevent these hidden flaws from tripling your manufacturing costs.