In PCB through-hole assembly, solder bridging during the wave soldering process is a recurrent defect that directly affects product reliability, yield, and delivery stability. Even minor deviations in process settings can cause solder to overflow from plated through-holes, resulting in solder bridges, contamination, and electrical reliability risks. For manufacturers, improper parameter control translates to rework, increased scrap rates, and production delays.

This article focuses on wave soldering solder bridging prevention through parameter optimization, based on PCBGOGO’s verified production standards and engineering experience.

1. Why Wave Soldering Parameters Cause Solder Bridging

Wave soldering performance is driven by five interdependent parameters:

• Solder temperature

• Preheating temperature

• Conveyor/transport speed

• Wave height

• Wave angle

Any misalignment in one parameter disrupts the balance of solder viscosity, wettability, and filling pressure in the through-hole, resulting in defects such as:

• Solder overflow and bridging

• Cold joints or incomplete fill

• Flux spatter and contamination

• Misalignment caused by thermal stress

Effective optimization requires controlling these variables as a combined system rather than in isolation.

2. Optimal Solder Temperature Control

Solder viscosity decreases as temperature increases; high temperatures promote fluidity and increase the risk of solder running through the barrel and forming bridges. Low temperatures reduce wetting, hindering solder fill.

For Sn63/Pb37 alloy, PCBGOGO’s process validation identifies the optimal soldering temperature as:

255 ± 5°C (measured at the effective wave contact zone)

Recommendation:

• Avoid relying solely on solder pot temperature readings

• Measure at the solder wave’s working interface to prevent calibration errors

This ensures adhesion, wetting, and fill quantity remain controlled without driving overflow.

3. Preheating to Control Moisture-Induced Defects

PCB substrates absorb moisture during storage. When exposed to high-temperature solder, this moisture vaporizes rapidly and disrupts the solder meniscus in the through-hole, pushing molten solder upward and creating bridging.

PCBGOGO applies the following standard:

• Preheat temperature: 90–110°C

• Preheat time: 60–90 seconds

• Target substrate moisture: < 0.05%

Benefits include:

• Reduced moisture shock

• Lower thermal stress differentials

• Increased pad stability and dimensional accuracy

This step is especially critical for FR-4 boards used in humid environments or after long storage cycles.

4. Coordinated Conveyor Speed and Wave Height Settings

Transmission speed determines the contact duration between PCB and solder wave:

Recommended conveyor speed:

1.0–1.8 m/min, adjusted according to through-hole density

• Dense designs → slower speed

• Sparse layouts → faster speed

Wave height should cover the through-hole base by 1–2 mm.
Excess wave height elevates hydraulic pressure and forces solder through the barrel.

5. Wave Angle to Improve Solder Drainage

Adjusting the guide rail angle to 3°–5° leverages gravity to promote solder return flow. This reduces residual solder in the barrel and prevents post-solder pooling that later results in bridging.

PCBGOGO’s adjustable-angle guide rail systems enable on-the-line tuning for different:

• PCB thicknesses

• Plating quality levels

• Copper distribution patterns

This adaptive configuration is especially effective for high-density or mixed-technology boards.

6. Building a Closed-Loop Wave Soldering Control System

To achieve consistent wave soldering solder bridging prevention, PCBGOGO utilizes a closed-loop control architecture:

Through this framework, PCBGOGO maintains solder bridging defect rates at well below industry averages, enabling stable throughput for small-batch and mass production.

Conclusion

Preventing solder bridging during wave soldering is not a single-parameter task but a system engineering challenge requiring alignment of design, material condition, and process execution. By optimizing solder temperature, preheat conditions, conveyor dynamics, wave geometry, and drainage angles, manufacturers can effectively suppress solder overflow at the source.

For companies seeking scalable, high-yield PCB assembly, PCBGOGO provides engineering-backed process configuration services and validated parameter sets for diverse board types and application classes.