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EMS handbook

1. Automated THT: selective & wave

Wave and selective soldering subject a PCBA to significant thermal activity, requiring strict parameter management. Improperly calculated parameters cause thermal shock to SMT components or result in insufficient solder on THT joints.

This chapter defines wave dynamics, flux application, and preheating profiles. It specifies machine setups required to achieve reliable barrel fill while minimizing bridging, icicles, and excessive dross generation.

  • 1.1 THT-friendly design

    Through-Hole Technology (THT) remains valuable for providing mechanical stability (such as for heavy connectors or relays), accommodating high-power components, and creating joints that benefit from s...

  • 1.2 Fluxing & preheat control

    Through-hole soldering is a strictly thermal process. The precisely controlled combination of fluxing and preheating ensures metal surfaces are chemically clean while protecting the component from the...

  • 1.3 Selective solder programming

    When assembling a mixed-technology board—where sensitive SMT components are located closely to THT pins on the same side—wave soldering the entire assembly is impossible without causing collateral the...

  • 1.4 Wave solder setup

    Wave soldering is a traditional, robust mass production technique. Its effectiveness relies on the strict, thoughtful alignment of mechanical and thermal parameters. Establishing baseline setup parame...

  • 1.5 Common defects & corrections

    When encountering solder balls, non-fills, or bridging, process parameters must be systematically reviewed before attributing the issue solely to the solder wave. These defects strongly correlate with...