Case Study: Resolving PTH Fitment & Stencil Challenges for an Industrial Electronics OEM

How PCB Power's engineering intervention eliminated a component-PCB incompatibility and upgraded the printed circuit board assembly process for long-term quality gains.

Customer Snapshot

The Assembly Challenge Faced by an Industrial Electronics OEM

The customer submitted PCB design for Turnkey PCB assembly where a fitment incompatibility was identified between the PTH component lead diameters and the drilled hole sizes on the PCB — specifically at reference designators SC1, SC2, SC3, SC4, and several others.

The mismatch meant that standard component insertion was not feasible without risk of damage or poor solder joint integrity. Additionally, the existing PCB stencil design did not account for solder paste application on the PTH pads, which would have necessitated manual soldering a process prone to inconsistency and harder to control at scale.

Two compounding problems had to be solved simultaneously:

• Mechanical fitment of the component into an incompatible hole
• Soldering process reliability for PTH parts on a mixed-technology printed circuit board assembly

Technical Solution for the Industrial Electronics OEM Assembly Requirement

PCB Power's engineering team proactively reviewed the design-for-manufacturability (DFM) rules and implemented a design-level fix — not just a one-time workaround. The PCB stencil modification and hole adjustment were logged for future printed circuit board assembly runs, ensuring continuity and consistency across repeat orders.

Our engineering and production team reviewed the assembly data and took a two-step approach:

• Hole Modification & Component Fitment Despite the incompatibility being outside standard PCB assembly scope, we manually assembled the components and modified the hole dimensions. This was documented and incorporated into the job specification so that future orders would not face the same issue — eliminating repeat escalations.
  
  
• PCB Stencil-Based Solder Paste Process for PTH Parts Rather than defaulting to manual soldering, the engineering team designed specific solder paste apertures on the PCB stencil for the PTH pads. This allowed the PTH components to be processed through the reflow oven alongside SMT components, resulting in:  
• Consistent and repeatable solder joints
• Better solder fillet formation
• Improved barrel fill from both top and bottom sides of the board
• Elimination of manual soldering variability

Quality Checks That Help an Industrial Electronics OEM Move Ahead

The assembled boards were subjected to a multi-stage inspection process:

• AOI (Automated Optical Inspection) — surface-level solder and component placement verification
• X-Ray Inspection — barrel fill and internal solder joint quality validation
• Visual Inspection (VI) — final workmanship check

From Challenge to Completed Production

With the fitment issue resolved and the revised PCB stencil process validated, the boards moved smoothly into full production. The printed circuit board assembly was completed without further stoppages, rework loops, or quality escapes. All units cleared AOI, X-Ray, and Visual Inspection at first pass — a direct result of the process-level changes implemented by PCB Power's engineering team. The updated hole specifications and stencil aperture design were formally documented and locked into the production records, ensuring that subsequent PCB assembly orders for this customer can be executed with zero ambiguity and consistent output quality from day one.

Key Takeaway

If your designs involve mixed PTH/SMT printed circuit board assembly, component-to-hole dimensional compatibility is a frequently overlooked variable — especially when components are sourced from multiple vendors with slight dimensional variations. A mismatch at this stage can cascade into soldering defects, rework costs, and field failures.

PCB Power's approach in this case demonstrates that the right intervention isn't just fixing the immediate problem — it's re-engineering the PCB assembly process so the fix holds across future production runs.

Ready to avoid rework and production delays?

Partner with PCB Power for reliable DFM and engineering support before production - because the right intervention at the right time makes all the difference.

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