Through-hole components still carry the mechanical and electrical loads that surface-mount parts cannot — the heavy connectors, power transistors, transformers, and large capacitors that anchor a board to its enclosure and endure repeated mating cycles. When these parts need to be joined to a PCB in volume, wave soldering remains the most efficient, most repeatable, and most economical method available. This guide explains how a modern wave soldering PCB assembly service works, what to look for in a partner, and why the right manufacturing setup matters for long-term product reliability.
Wave soldering passes the bottom side of a populated PCB over a continuously flowing wave of molten solder alloy. Before the board reaches the wave, it travels through a fluxing station that coats the plated through-holes and pads to remove oxides and improve wetting. A preheating zone then gradually raises the board temperature to reduce thermal shock and activate the flux chemistry.
At the wave itself, the board typically meets two successive solder flows: a turbulent wave that drives solder into tight pin gaps and breaks through residual oxide, followed by a smooth laminar wave that sweeps away excess material and leaves clean, well-formed fillets. Contact time is measured in seconds, yet those seconds determine whether every joint is sound or whether bridges, pinholes, and cold joints will trigger rework downstream.
The result is a board where every through-hole pin is mechanically anchored and electrically connected in a single pass — something manual soldering cannot match for throughput or consistency.
Despite the dominance of surface-mount technology, through-hole assembly remains essential for components that demand physical robustness. Connectors that face repeated plugging and unplugging, power devices that dissipate heat through their leads, transformers and inductors with significant mass, and large electrolytic capacitors all rely on the mechanical grip that only a plated through-hole solder joint can provide.
Many real-world products combine both technologies on the same board. A mixed-technology assembly runs SMT components through reflow soldering first, then sends the board through wave soldering for the through-hole parts — with SMDs on the wave side protected by pallets or adhesive. Managing that handoff cleanly is one of the clearest markers of a capable through-hole soldering service.
Not every factory that owns a wave soldering machine can deliver consistent, defect-free results at scale. The difference lies in process control, equipment quality, and the engineering discipline wrapped around the soldering line itself. When evaluating a partner, consider these factors together rather than in isolation:
A capable through-hole line is more than a wave soldering machine — it is a sequence of controlled operations. At Farway Electronic in Shenzhen, the DIP plug-in welding process runs from component forming and insertion, through wave soldering, lead cutting, repair welding, and board washing, all the way to functional testing. Two dedicated plug-in lines and two wave soldering machines are backed by twenty-four rear-welding stations and a board-washing machine, giving the line capacity to absorb volume spikes without skipping inspection steps.
The same facility pairs its DIP lines with two SMT production lines using Yamaha placement systems and Jintuo ten-zone reflow ovens. This co-location matters: when SMT and through-hole live under one roof, mixed-technology boards move from reflow to wave soldering without the transit damage, scheduling friction, and traceability gaps that come from splitting the job across two suppliers.
For teams sourcing both sides of a mixed-technology board, a partner offering dip plug-in and SMT mixed assembly service eliminates a category of coordination risk that is easy to underestimate until a pallet of reflow-finished boards sits waiting for a third-party wave soldering slot.
A soldered board is only the midpoint of a reliable product. Environmental protection and functional verification determine whether that board survives in the field. After wave soldering, the same Shenzhen facility applies automated conformal coating to guard against moisture, dust, corrosion, and thermal cycling — supporting boards up to 550 mm × 470 mm with selective masking, double-sided spraying, and controlled bake times.
For components that need deeper encapsulation, low-pressure injection moulding provides a sealed barrier against water, vibration, and chemical exposure. Four low-pressure moulding machines support applications from medical sensors and automotive electronics to LED lighting and battery packs.
Testing spans the full chain: manual visual inspection, AOI, FAI first-article inspection, X-ray, ICT, thermal imaging, high- and low-temperature reliability testing, online and offline program burning, and FCT functional testing. A one-year free-repair commitment covers eligible non-external defects arising during standard customer use, tying the inspection effort to a concrete warranty obligation rather than leaving it as an internal metric.
Certifications are not decoration — they are the audit trail that proves a process is repeatable. Farway operates under ISO 9001 for quality management, IATF 16949 for automotive, ISO 13485 for medical devices, and ISO 14001 for environmental management. Product-level certifications include UL, RoHS, SGS, and REACH. The PCB implementation standard is IPC-A-600H, and PCBA assembly follows IPC-A-610. These should still be verified directly during supplier qualification, but their presence signals a documented, audited system rather than an ad-hoc workshop.
Many through-hole projects stall not at the soldering stage but at the handoffs — between PCB fabrication and assembly, between component sourcing and production, between SMT and DIP, between testing and finished-product packaging. A one-stop partner collapses those handoffs into a single controlled flow.
Farway's manufacturing chain runs from PCB board making and component procurement through SMT, DIP, conformal coating, low-pressure moulding, PCBA testing, and finished-product box-build assembly. Component management covers authorised-channel sourcing, incoming inspection, ERP-traced FIFO warehousing, anti-static storage, and controlled temperature and humidity. For new products, NPI support and DFX review are available before production commitment. The company has served over 100 industry customers across more than 20 countries and regions since its founding in 2018.
That breadth is what lets a single partner carry a board from bare laminate to boxed product — and what lets an engineering team spend its time on design iteration instead of vendor coordination.
If your project involves through-hole components, mixed-technology boards, or a full turnkey build from PCB to finished product, talk to a partner that can run the entire line under one roof. Farway Electronic offers wave soldering, SMT assembly, conformal coating, low-pressure moulding, PCBA testing, and box-build assembly from its Shenzhen facility — with IATF 16949, ISO 13485, and IPC-A-610 compliance. Reach out at sales@farway.hk or call 181 2472 7402 to discuss your BOM and get a quotation.
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