What is Selective Soldering?

How does it work, and what’s the benefit of employing selective soldering machines?

These are all fantastic questions to have, especially if you’re considering switching to a new soldering method.  Selective soldering, simply put, is a method of soldering components to a printed circuit board in a much faster period of time than doing so by hand.  It’s one of the most widespread and an effective soldering method, as it has become one of the dominant forms of soldering in manufacturing applications.  Put simply, selective soldering is an automated soldering process by which components are soldered to a PCB all at once or in very quick succession via means of automation.  In the most generic terms possible, a PCB enters a selective soldering machine with components loosely attached to it.  Solder is then applied via whatever means of selective soldering the machine in question uses.

Selective Soldering Processes Includes:

  • Aperture Tooling Over Wave Soldering – this is where the board is dragged through a wave of solder, created by agitating a pool of molten solder.  Areas of the board that aren’t to be soldered are masked for protection.
  • Selective Dip Solder Fountain – this process involves solder fountains, placed at the exact points where the board is to be soldered.  The board is dipped into the fountains, soldering components at the correct points and leaving other areas untouched.
  • Miniature Wave Select Solder Fountains – this process creates a solder wave as well, though the board is manipulated to be soldered in the correct locations.  This method does not require the aperture tooling and masking that aperture over wave soldering does.
  • Laser Selective Soldering – this process uses a laser to solder precise points.  Often controlled via CAD program, this method is the utmost in precision.  After the solder is applied, the finished board leaves the soldering machine to cool and onward in its journey through the manufacturing process.  In short, selective soldering is an automated soldering process by which soldering a PCB is done by automation rather than by hand.

Why Should I Consider A Selective Soldering System?

A selective soldering system is preferable in some applications over other soldering methods.  Specifically, it’s an alternative to hand soldering and re-flow ovens.  Hand soldering certainly has its place in certain applications, such as hand-assembled electronics such as instrument amplifiers and other applications where the craftsman’s touch is required.  The precision and delicacy that human hands are capable of certainly is not to be ignored.  However, hand soldering ceases to be a boon and becomes a liability where production volume is required.  Re-flow ovens are certainly capable of high-volume production.  However, this process has some key weaknesses that selective soldering does not possess.  Specifically, circuit boards are more susceptible to heat damage in re-flow ovens as the temperatures required to melt solid solder and bake the board together can damage heat-sensitive circuit boards.  Additionally, re-flow ovens are better suited to less precise work.

What Are The Benefits Of Selective Soldering?  The benefits of selective soldering are realized best by the manufacturer with a product better-suited for selective soldering as opposed to re-flow oven or hand soldering.

For instance, does your company make a boutique product, using older or otherwise non-standard components due their unique properties?  Then selective soldering probably isn’t your best bet.

Are your products largely made with a high volume of small boards that don’t require precise soldering?  Selective soldering could work for you, but it’s using a very precise tool for imprecise work.

Do your products require precise soldering, but also have to be produced quickly due to a large overall volume of demand? Are your boards larger or otherwise sensitive to heat?  Then selective soldering is definitely for you.  For the operation that requires it, selective soldering machines assemble boards and components quickly, precisely and without damaging delicate boards that would otherwise be destroyed by re-flow or would take too long to solder by hand.  These are precisely the kind of companies that employ selective soldering and use them to deliver the products their customers need.

If this sounds like the kind of soldering your business requires, contact us today at sales@rpsautomation.com or +1(509) 385-1228

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