DFM/DFA Analysis Solution: How to Cope with Through-hole Component Defects

Introduction: Why Through-Hole (TH) Component Defects Matter in PCB Manufacturing

In PCB design and assembly, through-hole (TH) components remain widely used for their mechanical strength and reliability. However, they are also prone to manufacturing and assembly defects that can significantly impact soldering quality, product reliability, and production yield.

Typical issues such as hole-to-lead mismatch, pad misalignment, and solder insufficiency are often not discovered until late production stages, leading to costly rework and delays.

A proactive DFM/DFA (Design for Manufacturing / Assembly) analysis approach helps detect these issues early in the design phase, ensuring higher manufacturability and assembly success.

Common Through-Hole (TH) Component Defects in PCB Design

1. Excessive Clearance Between Plated Hole and Lead

When the clearance (C) between the plated hole and the component lead exceeds recommended limits (e.g., > 0.4mm), it may lead to incomplete solder filling, increased porosity, weak solder joint strength and reduced long-term reliability.

2. Improper Pad-to-Lead Size Matching

Incorrect pad sizing relative to lead diameter can disrupt solder surface tension balance:

Oversized pad + thin lead → insufficient solder volume, weak joints, “shriveling” effect
Undersized pad + thick lead → insufficient solder coverage, reduced mechanical strength

Proper pad-lead ratio design is essential for stable solder formation.

3. Pad and Trace Design Interference

When pads are too close to copper traces or partially connected:

Solder is unevenly distributed due to surface energy effects
Solder tends to flow toward adjacent copper areas
Risk of weak or incomplete solder joints increases significantly

4. Misaligned Pad and Plated Hole (Concentricity Issue)

If the hole is not centered within the pad:

Solder distribution becomes asymmetric
Uneven wetting around the lead occurs
Mechanical and electrical reliability is reduced

5. Oversized Through-Hole Diameter

Excessively large hole diameters may cause: solder leakage, component floating during reflow/wave soldering, pins not properly exposed and increased risk of bridging and flux residue.

6. Undersized Through-Hole Diameter

If the hole is too small, component insertion becomes difficult or impossible, risk of lead damage increases, poor solder penetration and possible damage to plated through-hole (PTH) walls during press-fit processes

7. Flat lead plated hole design, as shown in the picture below, the DIP flat pins are matched with the round holes on the PCB. Incomplete filling can easily happen thus decreasing soldering quality.

DFM/DFA solution to these common defects

Nowadays, DFM/DFA solution has been an efficient approach to optimizing the design of a product for its manufacturing and assembly process, thus helping make a better product at lower cost. To these defects of the TH component, Vayo Technology’s VayoPro-DFM Expert provides a 3D DFM/DFA analysis solution.

The software comes with 1500+ checking rules, including 300+ rules for the fabrication process and 1200+ for the assembly process. The checking items cover the component, pad, fiducial, testpoint, signal layer, silkscreen, etc. Besides, these rules are continuously innovated to follow the trends and demands. Vayo Technology also offers on-demand rule development services to meet the different needs of clients.

What’s more, based on 3D component entity library of the software, upon the completion of DFM/DFA analysis, it would automatically generate a 3D DFM/DFA analysis report, more intuitively displaying the location of defects.

Learn more details, please visit www.vayoinfo.com or reach us via email: business@vayoinfo.com.