Not every circuit board lives inside a climate-controlled enclosure. Industrial controllers ride on factory floors laced with vibration. Automotive modules endure temperature swings from freezing mornings to engine-bay heat. Power supplies carry heavy current through transformers and connectors that surface-mount adhesives alone cannot hold. For boards like these, through-hole technology and
wave soldering service remain the backbone of reliable electronics manufacturing — and choosing the right partner for that process directly shapes how your product performs in the field.
Why Through-Hole Assembly Still Matters
Surface-mount technology dominates modern PCB layouts, but through-hole components are irreplaceable in specific scenarios. Connectors that undergo repeated mating cycles, transformers and relays that carry significant current, large capacitors that need mechanical anchoring, and terminal blocks that bear physical wire stress — all of these depend on leads passing through the board and soldered on the opposite side for structural integrity.
The solder joint itself is the difference. A through-hole joint wraps solder around a plated barrel and a lead, creating a mechanical bond far stronger than a surface-mount pad alone. When a product must survive vibration, thermal cycling, or physical handling, that bond is what keeps the board alive. This is why industries from automotive to medical devices continue to specify through-hole components on boards that also carry dense SMT circuitry — and why the
through-hole soldering service behind those joints cannot be treated as an afterthought.
How Wave Soldering Works — and Why Process Control Decides Quality
Wave soldering is the high-volume soldering method for through-hole boards. The board travels on a conveyor through a flux application station, enters a preheat zone that activates the flux and brings the board to a controlled temperature, and then passes over a molten solder wave. The solder wave contacts the bottom of the board, capillary action draws it up through the plated barrels, and joints form simultaneously across the entire board.
The concept is simple. The execution is not. Solder temperature, conveyor speed, preheat profile, flux type and coverage, wave height, and nitrogen atmosphere all interact. Too little preheat and the flux fails to activate; too much and the board warps. Too fast a conveyor and hole fill is incomplete; too slow and you get bridging. This is why equipment quality and operator experience matter as much as the process itself.
Farway Electronic operates Nitto wave-soldering equipment on two dedicated DIP plug-in production lines at its 2,000-square-metre facility in LongGang, Shenzhen. The DIP process runs from component forming and insertion through wave soldering, lead cutting, repair welding, board washing, and functional testing — all under IPQC and QA sampling control, with 24 rear-welding stations staffed by trained and certified operators.
The Complete DIP Process: From Component Forming to Functional Test
A reliable through-hole assembly is never just about the solder wave. It is a multi-step workflow where each stage protects the integrity of the next. Farway's published DIP process covers the full chain:
- Component forming: Axial and radial leads are cut and bent to the correct pitch so parts ｉｎｓｅｒｔ cleanly without stressing pads or barrels.
- Insertion: Operators place through-hole components by reference designator, verifying orientation, polarity, and lead fit before the board advances.
- Wave soldering: The board passes through flux, preheat, and the molten solder wave on Nitto equipment, with parameters set for board thickness, component density, and solder alloy.
- Lead cutting: Excess leads are trimmed to specification to prevent shorts and meet mechanical clearance requirements.
- Repair welding: Trained operators inspect every joint and rework any insufficient fill, bridging, or cold joint at 24 dedicated rear-welding stations.
- Board washing: A board-washing machine removes flux residues and contaminants to prepare the assembly for coating and testing.
- Functional testing: Boards proceed to PCBA testing, where FCT functional testing, ICT, and other inspection methods verify electrical performance before release.
Mixed SMT + DIP Assembly: One Board, Two Technologies
Most real-world products are not pure through-hole or pure SMT. A typical industrial controller might have hundreds of 0402 passives and fine-pitch QFNs on the top side, plus connectors, relays, and electrolytic capacitors on the bottom that need through-hole soldering. Managing both technologies on one board requires sequencing: SMT placement and reflow first, then through-hole insertion and wave or selective soldering, with masking or fixtures protecting already-soldered components.
Farway supports this
one-stop smt + dip assembly service by running two SMT lines alongside two DIP lines in the same facility. Yamaha placement machines handle 01005 components and BGA at 0.2 mm pitch, while the DIP lines manage the through-hole side. Because both processes live under one roof, there is no handoff between vendors, no shipping delay between reflow and wave soldering, and a single quality system — IPC-A-610 assembly standard, IPQC sampling, AOI, and FAI inspection — covers the entire board.
Production Capability at a Glance
Farway's through-hole and wave soldering capabilities are backed by specific, published equipment and process data:
| Capability | Detail |
|---|
| DIP production lines | 2 dedicated plug-in lines |
| Wave soldering equipment | Nitto wave-soldering machines |
| Rear-welding stations | 24 staffed stations for repair and rework |
| Board washing | Dedicated board-washing machine |
| Max PCBA board size | 510 mm × 460 mm |
| Board thickness range | 0.2 mm – 8 mm |
| Board types supported | Rigid, flexible, rigid-flex; 1–32 layers |
| Assembly standard | IPC-A-610 |
| Quality certifications | ISO 9001, ISO 13485, IATF 16949, ISO 14001 |
These figures come from Farway's published process-capability page and should be confirmed directly for project-specific qualification.
Inspection and Testing: Catching Defects Before They Ship
Wave soldering can produce defects that are invisible to the naked eye — insufficient hole fill, cold joints, pinholes, or bridging under dense component clusters. Farway addresses this with a layered inspection system that begins during assembly and continues through final testing:
- Plug-in visual inspection checks component orientation and lead condition immediately after insertion.
- AOI optical inspection scans solder joints for wetting, bridging, and missing solder after the wave.
- X-ray inspection verifies hidden joints on components where visual access is blocked.
- ICT circuit testing confirms electrical connectivity on critical nets.
- FCT functional testing powers the board and exercises its actual operating behaviour.
- Thermal imaging inspection identifies hot spots and abnormal current paths under load.
For eligible non-external defects arising during standard customer use, Farway also states a one-year free-repair commitment — a tangible signal that the company stands behind its solder joints beyond the shipping dock.
Where Through-Hole Assembly Makes the Difference
Farway's through-hole and wave soldering capabilities serve customers across industries where mechanical reliability and power handling are non-negotiable:
- Automotive electronics: Window-lifter controllers, playback function boards, and power distribution modules that face vibration and temperature extremes.
- Industrial control: PLCs, motor drivers, and factory automation boards where connectors and terminal blocks carry both signal and power.
- Power and new energy: Charging modules and power converters built around transformers, large capacitors, and heat-dissipating components.
- Security systems: Alarm panels and access controllers that must remain operational for years in varied environments.
- Medical devices: Equipment boards where long-term electrical stability and regulatory traceability are mandatory.
- Communications: Networking hardware with robust connectors rated for repeated field servicing.
Why Partner with Farway for Wave Soldering
Farway Electronic has served more than 100 industry customers across more than 20 countries and regions since its establishment in 2018. Its LongGang, Shenzhen facility combines PCB fabrication, component management, SMT, DIP through-hole assembly, conformal coating, low-pressure injection moulding, PCBA testing, and finished-product assembly under one quality system — certified to ISO 9001, ISO 13485, IATF 16949, and ISO 14001.
For through-hole boards specifically, that means you get Nitto wave-soldering equipment, certified operators, a full rear-welding and rework station, IPC-A-610 workmanship standards, and integrated functional testing without managing multiple vendors. Whether your project is a prototype from one piece or a medium-to-large production batch, the same process controls apply.
Get Your Through-Hole Assembly Quote
Send your Gerber files, BOM, and assembly drawings to Farway Electronic for a rapid quotation. The engineering team will review your board layout, recommend wave soldering or selective soldering based on component distribution, and confirm the full DIP process path from insertion to functional test.
Email: sales@farway.hk | Phone: 181 2472 7402 | Website: www.farway.hk
