Selective Soldering Machines

What Does a Selective Soldering Machine Do?

A selective soldering machine applies flux and solder only to specified through-hole joints. The programmed motion system controls the soldering position, nozzle height, movement path, contact time, wave height and solder temperature for each PCBA.

Selective Fluxing → Preheating When Required → Nitrogen-Assisted Mini-Wave Soldering → Solder-Joint Inspection

Unlike conventional wave soldering, selective soldering does not require the complete underside of the PCBA to pass across a full solder wave. This makes the process suitable for mixed-technology assemblies containing both reflow-soldered SMD components and inserted THT components.

The controlled process addresses production problems such as inconsistent hole fill, solder bridging, cold joints, excessive solder and variation between manual soldering operators.

Selective Soldering Machine Models

Compact PCB Selective Soldering Machine – DEZ-H3200A

The compact PCB selective soldering machine DEZ-H3200A processes PCBAs with a maximum soldering area of 300 × 250 mm.

After manual loading, the programmable XYZ platform moves the PCBA between selective fluxing and nitrogen-assisted mini-wave soldering positions. It is suitable for smaller PCBAs, prototype production and high-mix, low-volume THT assembly where a dedicated preheating stage is not required.

Offline Automatic Selective Soldering Machine – DEZ-H3500A

The offline automatic selective soldering machine DEZ-H3500A processes mixed-technology PCBAs with a maximum soldering area of 350 × 410 mm.

The machine automatically completes selective fluxing and programmed mini-wave soldering after the operator loads the PCBA. It is suitable for larger PCBAs, frequent product changes and manufacturers replacing variable hand soldering without installing an inline system.

Offline Selective Wave Soldering Machine with Preheating – DEZ-H3600A

The offline selective wave soldering machine DEZ-H3600A combines selective fluxing, lower infrared preheating and nitrogen-assisted mini-wave soldering.

It processes PCBAs with a maximum soldering area of 400 × 300 mm. The controlled preheating stage makes this model suitable for thick, multilayer or high-thermal-mass PCBAs that require additional heating before soldering.

Inline Selective Soldering Machine – DEZ-H3800S

The inline selective soldering machine DEZ-H3800S automatically transfers PCB carriers through selective fluxing, upper and lower infrared preheating and programmed mini-wave soldering.

It supports carriers up to 400 × 400 mm and processes each carrier through the complete sequence before transferring it downstream. The H3800S is suitable for medium-volume THT assembly requiring automatic line transport.

Three-Station Inline Selective Soldering Machine – DEZ-H3900A

The three-station inline selective soldering machine DEZ-H3900A separates selective fluxing, dual-sided preheating and mini-wave soldering into individual process stations.

Three carriers can occupy different stations at the same time. The system supports carriers up to 500 × 600 mm and a maximum soldering area of 500 × 450 mm. It is designed for large PCBAs and continuous production where parallel processing is required to reduce waiting between stages.

How to Select a Selective Soldering Machine

Offline or Inline Production

The compact PCB selective soldering machine DEZ-H3200A, offline automatic selective soldering machine DEZ-H3500A and offline selective wave soldering machine DEZ-H3600A suit high-mix production, manual loading and installation beside an existing assembly line.

The inline selective soldering machine DEZ-H3800S and three-station inline selective soldering machine DEZ-H3900A are intended for production lines requiring automatic carrier transfer.

PCBA and Carrier Size

Machine selection must consider the PCBA or carrier dimensions, PCB thickness, carrier weight, component height and available clearance below the board.

The soldering area and carrier capacity are not the same on every model. Send the board or carrier drawing before confirming the machine configuration.

Preheating Requirement

The DEZ-H3600A provides lower infrared preheating for offline production. The DEZ-H3800S and DEZ-H3900A provide upper and lower preheating for inline production.

The required preheating process depends on PCB thickness, copper content, thermal mass, flux characteristics and the required solder penetration through plated holes.

Production Capacity

The DEZ-H3800S moves one carrier through the complete process sequentially. The DEZ-H3900A allows different carriers to undergo fluxing, preheating and soldering simultaneously.

The appropriate machine should be selected using the required takt time and actual programmed soldering path rather than daily board quantity alone.

Soldering Nozzle Access

Soldering nozzle selection depends on pad dimensions, pin arrangement, component clearance and the distance between the THT joint and nearby components.

DEZ requires the THT coordinates and bottom-side component keep-out areas to evaluate whether a standard nozzle can reach each soldering point or a customised nozzle is required.

Selective Soldering Applications

DEZ selective soldering machines are used for connectors, terminal blocks, relays, transformers, switches, sockets, pin headers and other inserted components on mixed SMT and THT PCBAs.

The process normally follows SMT reflow and THT component insertion. It is completed before solder-joint inspection and any required post-solder cleaning.

The Selective Soldering Optimization for THT Assembly application page explains how board layout, flux application, preheating, solder-nozzle access and process parameters affect selective soldering results.

Industries Using Selective Soldering Machines

In automotive electronics manufacturing, selective soldering machines process control modules, lighting controllers, battery-management boards and other PCBAs containing connectors, relays, sensors and high-current terminals.

In medical device manufacturing, programmed soldering parameters support repeat production of equipment PCBAs containing connectors, terminals and mixed SMT/THT components.

For EMS and contract electronics manufacturing, offline and inline selective soldering machines can be selected according to product mix, PCBA dimensions, takt time and changeover frequency.

Nitrogen Supply for Selective Soldering

DEZ selective soldering machines use nitrogen around the soldering nozzle to limit oxidation and support solder wetting.

The SMT nitrogen generator for selective soldering DEZ-D59-2N produces nitrogen on site from clean, dry compressed air. Its output must be compared with the selected soldering machine’s continuous and peak nitrogen consumption before the nitrogen-supply configuration is confirmed.

PCBA Cleaning After Selective Soldering

Selective soldering and PCBA cleaning are separate production stages. Whether cleaning is required depends on the flux system, visible residue, ionic-cleanliness requirement, downstream coating process and PCBA construction.

When compatible flux residue, ionic contamination or loose solder balls must be removed, compare the available PCBA cleaning machines according to the contamination location and required cleaning method.

Selective Soldering Machine FAQ

What is the difference between selective soldering and wave soldering?

Selective soldering applies flux and a mini solder wave only to programmed THT joints. Conventional wave soldering normally passes a larger area of the PCB underside over the solder wave. View Wave Soldering Ovens.

The correct process depends on the component layout, production volume, bottom-side clearance and thermal restrictions.

Does selective soldering require nitrogen?

The current DEZ selective soldering machines use nitrogen-assisted mini-wave soldering. The required nitrogen purity, pressure and consumption must be confirmed for the selected machine.

Factories can use cylinders, a central supply or an appropriately sized nitrogen generator for selective soldering.

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