Wave Soldering

Wave soldering solders through-hole PCB leads by passing assemblies over a molten solder wave, delivering fast, repeatable joints at production volumes.

Overview

Wave soldering is a high-throughput soldering process for printed circuit boards (PCBs). The assembly passes over a controlled wave of molten solder after fluxing and preheating, wetting exposed pads and component leads to form electrical and mechanical joints—most commonly for through-hole parts, and sometimes for selective mixed-technology boards with proper masking.

Choose wave soldering when you need consistent joints across many boards, with short cycle times and stable process control (temperature, conveyor speed, solder alloy, flux chemistry). It’s well suited to fixtures/pallets, standardized board designs, and repeat builds.

Tradeoffs: it’s less flexible for one-offs, very fine-pitch SMT, or tall/heat-sensitive components. Board layout must manage solder bridging, shadowing, and thermal balance, and you’ll need clear requirements for alloy (lead-free vs SnPb), cleanliness/ionic residue limits, and inspection criteria.

Common Materials

  • FR-4 PCB
  • Copper pads
  • Tin-lead solder
  • SAC305 solder
  • Gold-plated contacts
  • Nickel plating

Tolerances

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Applications

  • Through-hole connector soldering on PCBs
  • Power supply PCB assemblies with large leaded components
  • Automotive ECU PCB assemblies
  • Industrial control board assemblies
  • LED driver PCB assemblies
  • Appliance control PCB assemblies

When to Choose Wave Soldering

Wave soldering fits repeat production of PCBs with significant through-hole content where fast takt time and joint consistency matter. It works best when the board is designed for wave rules (orientation, clearances, thermal balance) and you can run dedicated pallets/fixtures. Expect the biggest payoff at medium to high volumes with stable BOMs and layouts.

vs Hand soldering

Choose wave soldering when you need repeatable joint quality across many boards and want cycle time driven by conveyor speed, not operator time. It reduces labor variability and supports standardized inspection criteria, but needs wave-friendly layout and setup effort.

vs Reflow soldering

Choose wave soldering when the primary content is through-hole or you need strong barrel fill on plated through-holes at production rates. Reflow is typically better suited to fine-pitch SMT and paste-printed assemblies, while wave is constrained by bridging/shadowing rules and component heat exposure.

vs Torch Brazing

Choose wave soldering for PCB electrical interconnects where low-temperature solder joints, controlled wetting, and repeatable mass production are required. Torch brazing targets metal-to-metal assemblies with localized heat and higher-strength braze joints; it’s not appropriate for populated PCBs or dense electrical terminations.

vs Furnace Brazing

Choose wave soldering when joining component leads to PCB pads with controlled solder alloys and inspection to electronics standards. Furnace brazing is for batch joining of metal assemblies (often in controlled atmospheres) at much higher temperatures and with different filler metals; it’s not compatible with typical PCB materials or components.

Design Considerations

  • Orient through-hole components to minimize shadowing and reduce solder-bridge risk (leads aligned with conveyor travel).
  • Maintain adequate pad-to-pad and lead-to-lead spacing on the wave side to prevent bridging; call out any exceptions explicitly.
  • Use proper thermal reliefs on plane-connected through-hole pads to support wetting and consistent barrel fill.
  • Define solder alloy, flux type, cleanliness/ionic residue limits, and acceptance standard (e.g., IPC-A-610 class) on the drawing or build notes.
  • Identify components that must be masked, glued, or pallet-supported (connectors, switches, tall parts) to avoid solder intrusion and float.
  • Provide a clear BOM and polarity/orientation documentation; mixed-technology boards often need pallets or selective masking, which drives quote and yield.