S-100B Desktop Selective Soldering Machine: High-Mix, Low-Volume THT Soldering by Southern Machinery

Through-hole (THT) soldering rarely gets the planning attention that SMT placement does — yet in high-mix, low-volume production it is often where quality, changeover time and consumable budgets quietly leak away. The S-100B desktop selective soldering machine from Southern Machinery is built to change that: fixture-free, programmable soldering that applies flux, preheat and solder only where the program calls for it, on a bench-friendly desktop footprint.

For EMS and ODM factories running small batches with frequent board changes, the S-100B turns changeover into a software step instead of a tooling project, and gives manufacturing engineers a repeatable soldering process they can measure.

What is this machine used for?

What is this machine used for? The S-100B is a desktop selective soldering system for high-mix, low-volume (HMLV) THT assembly. Rather than flooding the whole board with solder as a full wave line does, it moves a solder nozzle to each programmed joint and applies flux, preheat and solder selectively. No fixtures or pallets are needed — boards are programmed, not tooled.

That makes it a practical fit for labs, prototyping, small production lines and boards that change often, where a full wave line cannot justify its footprint, energy cost or fixture overhead.

The hidden cost of THT soldering in high-mix production

Manual soldering and whole-board wave soldering both carry costs that are easy to underestimate:

• Manual soldering is inconsistent. Joint quality varies from operator to operator — quality depends on the shift, not the process.
• Fixture costs eat margin. Every board variant needs its own fixture or pallet, so high-mix lines drown in tooling spend and changeover time.
• Big wave machines are overkill. A full wave line cannot justify its footprint and energy bill for small boards and short runs.
• Heat damages sensitive parts. Whole-board soldering exposes temperature-sensitive components to heat they were never designed for.
• Flux and dross waste. Broad-flux processes waste flux and generate solder dross that drains consumable budgets.
• High-mix lines can't wait. Traditional equipment was built for long runs, not for fast changeover.

How the S-100B changes the math on your floor

Precision motion: ±0.05 mm on a 3-axis XYZ robot

The S-100B uses a 3-axis XYZ robot with X/Y stepper motors plus a Z-axis servo with ball screw, running on high-quality linear guides. Positioning and repeatability are ±0.05 mm, on a heavy metal base plate with a net weight of roughly 100 kg for stability. The solder tip returns to the same position cycle after cycle, which is what keeps joints consistent and yield reliable.

ST-6 jet fluxing with a 1 L tank

Flux is applied with an ST-6 jet valve (imported quality), fed from a stainless steel / PP pressure tank with 1 L capacity. Selective flux application means far less flux waste than broad-flux processes.

Titanium solder pot with PID heating

The solder pot is titanium alloy with a stainless inner tank and holds 8 kg of solder. It is heated by an external heating plate with PID control from 0–400 °C and is lead-free compatible. Typical soldering temperature is 230–260 °C, set by the process.

N2 preheat

Nitrogen preheat protects the board and reduces oxidation. A nitrogen source is required as a consumable input.

PC-based control

The machine runs on PC-based industrial control with scan-data and GABER dual-mode programming — import board data and program joints directly, without building fixtures.

Nozzles: 4 mm, 5 mm and custom

Standard nozzles are 4 mm and 5 mm, made of alloy steel with silver plating. Custom shapes are available for unusual joint geometries, which matters for odd-form and mixed through-hole boards.

Typical applications

The S-100B is positioned for high-mix, low-volume THT assembly — the board profiles common in EMS, ODM, automotive electronics, medical electronics and industrial control, where batch sizes are small and board changes are frequent:

• R&D labs and prototyping benches
• Small production lines that share soldering capacity across multiple products
• Boards with temperature-sensitive components that need localized heat
• Mixed through-hole boards with connectors, relays, transformers and odd-form parts
• Pilot production before a board moves to a higher-volume soldering solution

Board size range, joint program and cycle time are confirmed during a sample board trial rather than assumed from a brochure.

How to integrate the S-100B into a complete PCB assembly line

The S-100B slots into the soldering stage of a PCB assembly flow, typically after SMT placement and THT insertion and before post-solder inspection and final test:

1. Solder paste printing
2. SMT placement
3. Reflow soldering
4. THT insertion (axial, radial, odd-form)
5. Selective soldering with the S-100B
6. AOI / visual inspection
7. Final test and packing

Because changeover is a programming step rather than a fixture change, the same desktop unit can run several board variants in one shift. Its compact, bench-friendly design suits small lines and cells that have no floor space for a full wave machine. Southern Machinery also supplies the surrounding line — SMT, THT, wave soldering, board handling and inspection — so the S-100B can be integrated as part of one accountable, cost-effective line solution with installation, operator training and spare parts support.

Key selection parameters checklist

Before requesting a configuration, prepare these inputs:

• Board dimensions and thickness range (confirmed during the sample trial)
• THT joint count and pitch
• Daily volume and required cycle time
• Nozzle size — 4 mm, 5 mm or custom shapes
• Nitrogen supply availability
• Solder alloy and target temperature profile
• Programming preference (scan data / GABER)
• Bench footprint, power and utility requirements
• Spare parts and training scope

Quality, capacity and ROI value

The value of the S-100B comes from process control rather than raw speed:

• Consistent joints. ±0.05 mm repeatability reduces touch-up and rework, and makes quality independent of operator shift.
• No fixture budget. Board variants change in software, shrinking changeover from hours to minutes.
• Less consumable waste. Selective fluxing and localized soldering reduce flux and dross compared with broad-flux processes.
• Component protection. Heat is applied only where needed, protecting temperature-sensitive parts.
• Reference capacity. The source technical overview cites 8000+ points per unit per day as a reference output for HMLV runs — an example for evaluation, depending on configuration, board and program, and subject to final technical confirmation.

The machine ships with a one-year warranty plus lifetime maintenance support, spare parts service and professional training, backed by Southern Machinery's global service network.

Engineering support: from sample trial to production

Southern Machinery proves the process on your boards before you commit:

1. Sample board trial — send PCBs for a free trial weld and yield report.
2. Technical consultation — board size, joint count and cycle time confirmed within 24 hours.
3. Configuration — nozzles, N2 setup and programming modes matched to your boards.
4. Installation and training — machine commissioned and operators trained on programming and daily use.
5. After-sales support — one-year warranty with lifetime maintenance and spares.

FAQ

What is the difference between selective soldering and wave soldering?

Wave soldering floods the whole bottom of the board with solder; selective soldering applies solder only to the joints you program, using a moving mini-wave or solder nozzle. That protects temperature-sensitive components and removes the need for fixtures on high-mix boards.

Which boards can the S-100B handle?

The S-100B is designed for high-mix, low-volume THT assembly — labs, prototyping, small production lines and boards that change frequently. Board size and joint program are confirmed during the sample trial.

Do I need nitrogen?

Yes — the S-100B uses N2 preheat to protect the board and reduce oxidation, and a nitrogen source is required as a consumable input.

What nozzle sizes are available?

Standard nozzles are 4 mm and 5 mm, made of alloy steel with silver plating; custom shapes are available for unusual joint geometries.

How is accuracy maintained?

The 3-axis robot uses X/Y stepper motors and a Z-axis servo with ball screw on high-quality linear guides, holding ±0.05 mm positioning and repeatability on a 100 kg stable base.

How do I get a price and delivery time?

Email info@smthelp.com or WhatsApp +86 136 0256 2576 with your board samples or drawings and volume. Quotation and delivery schedule are provided after technical confirmation — typically the same working day.

Get a configuration for your boards

Tell Southern Machinery your board size, THT joint count and daily volume. The team will trial-weld your samples, report the yield, and reply with a configuration, quotation and delivery schedule.

[Email for a Quote](mailto:info@smthelp.com) · WhatsApp · www.smthelp.com

Southern Machinery, founded in Shenzhen, China in 2011, has served 237+ customers worldwide with high-efficiency, cost-effective SMT/THT PCB assembly automation equipment — including SMT, THT, wave soldering, board handling and inspection — with global service, spare parts support and professional training.