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Benefits of Selective Soldering

Have you ever tried to remove an old screw, only to discover that its head is square-shaped and not slotted? It can be pretty frustrating, especially if you don’t have the right driver.

When assembling PCB, soldering through-hole elements on a printed circuit board (PCB) containing surface-mount parts can be a common need.

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Benefits of Selective Soldering

PCB assembly services provide automated selective soldering to supply efficient and also reliable results on mixed-technology boards.

This sort of soldering is specifically beneficial when you cannot implement traditional wave soldering due to the board layout complexity or on higher-volume assemblies where hand soldering may not be efficient.

The selective solder tool contains preheated and spray change areas to prepare the PCB for soldering.

It also consists of a nozzle that flows solder on a particular element lead. It is configured to exactly solder only through-hole components and not the entire circuit board.

Automated selective soldering is an essentially flexible process that creates dependable solder joints without heating components excessively.

You can configure these devices to make sure solder joints meet the IPC market Class 2 and Course 3 requirements.

However, some devices consist of both leaded and lead-free solder pots. This adaptability makes them usable in a wide range of jobs.

Selective soldering consists of mainly 3 phases:


involves applying flux on PCBs to eliminate the oxidized metal layer, on the area you intend to apply the solder, and sealing out any excess air to stop re-oxidation.


Once you apply the flux, the next step is to preheat the PCB


involves applying solder using variable and programmable solder nozzles via a fountain to particular board components in a constant stream.

The devices are separately configured for each soldering factor to control volume flux and establish soldering time for each PCB assembly circumstance, ensuring a much more dependable solder joint.

The degree of statistical process control for through-hole parts improves considerably when using selective soldering devices.

Selective soldering is ideal for higher-volume through-hole setup and for tasks with tight spacing between through-hole elements.

The nozzles can reach in between two through-hole leads without unnecessarily filling the whole area with solder.

A wider solder nozzle will efficiently manage the scenario If there is a dense focus of through-hole leads.

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When Selective Soldering is the Most Efficient

Some conditions are not ideal for both wave solder and hand soldering. In these instances, the only alternative is utilizing a selective solder system. Here are some of these conditions:

Tall components: Solder wave height has limitations; however, some elements are too high that they tend to block the wave from soldering the board.

Tight element spacing: When thru-hole elements are closely placed next to SMT elements, it could reduce the space you need to fix a safety component around the SMT parts.

This enables efficient wave soldering.

Unequal heating: Thick copper layered boards can be ineffective for hand soldering. It is also quite challenging to get a single soldering iron that will warm every thermally attached metal in the board thoroughly enough for the solder to move via the holes.

This makes selective soldering a good solder joint development.

Concentrated thru-hole pins: When you use big ports with a large number of pins, it can be challenging for a soldering iron to go through each pin to solder them all successfully.

Selective soldering can provide a remedy to all these situations. Besides its capability to be configured to manage unique pin arrangements, selective soldering also has other advantages.

The selective solder system will use a more infrared preheater to stabilize irregular heating of thick copper boards.

It can also use a broader nozzle that can solder two or three rows of connector pins in one pass, significantly reducing the expected soldering time.

This capability to quickly fuse hard-to-reach areas that were generally only hand-soldered is where selective solder radiates.

Bottom Line

Selective soldering offers PCB Assemblers all the tools they need to resolve those problems wave soldering can’t handle.

It can also solder high-pin elements without any heat damage effect that a reflow or wave process could bring about.

 Moreover, automated selective soldering can do this extremely repetitive job consistently whenever, as programmed. You can regulate a process action anytime it is automated.

While you can also control a manual process, such as hand soldering, to a specific extent, it’s not  100% effective.

That’s why you need to eliminate the human factor to enable a controllable procedure. Once you set an automatic selective soldering device, you can regularly execute the program applied to a particular design.