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EMS handbook

Book 05: Through-hole & mixed technology

While automated Surface Mount Technology relies on rigid, predictable variables, post-SMT operations manage inherent process variability. Through-Hole Technology and mixed assembly sit at the intersection of manual component insertion, dynamic liquid flux chemistry, and localized thermal gradients.

This book defines essential controls for Wave Soldering, Selective Soldering, and manual Rework. Final-stage protective measures, including Conformal Coating and Potting, are also detailed.

Establishing standard work in these processes builds consistent, reliable quality into back-end assembly.

  • 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...

  • 2. Manual THT & rework

    Manual soldering inherently introduces process variation. Relying on subjective techniques rather than documented standards increases defect rates and compromises long-term product reliability. Strict...

  • 3. Cleaning, depanelization, press-fit, coating & potting

    A PCBA may appear electrically and metallurgically flawless post-soldering, but remains vulnerable without rigorous downstream mechanical and chemical process control. Improper depanelization fracture...