What Are The Different Soldering Methods?

Types of Soldering Methods

Soldering is the act of joining two objects by means of melting a soft metal and using that as a bridge, though there are a number of soldering methods employed in making that happen. Which method is employed typically depends on the nature of the objects being joined. The nature of the soldering joint is also important, as each method is usually best reserved for certain specific applications.

Which soldering method is best? That depends on what is being soldered and how it must be soldered. That said, these are some of the most common types of soldering.

One of the most common methods of soldering in the current day is reflow soldering. Reflow, in the simplest terms, is where a certain amount of solid solder (often a paste) is deposited in a specific location on an object, which is then sent into a reflow oven. The heat of the reflow oven liquefies the solder, which solidifies after exiting the oven and creates the solder joint.

Reflow ovens are very common when soldering components to a printed circuit board or PCB, and especially when a large number of boards need to be soldered in the shortest amount of time possible. Provided proper flux and solder placement, and that nothing else goes wrong in the oven, it's a very efficient and safe method of producing mass quantities of product.

However, there are some drawbacks. Reflow ovens aren't the most exact tools and some of the finer joints may not be easily accomplished (or possible) with a reflow oven. Additionally, reflow is really only suited to surface-mounted components - or electronic components that are joined only to one side of the board.

Wave soldering is a form of selective soldering, where only certain parts of the board are soldered as components have to be secured to those parts of the board. This is done by creating a wave of liquid solder, which is accomplished by agitating a pool of it to produce wave formations. The board, treated with flux, preheated and possibly masked to avoid damaging components, is dragged through the wave so components are soldered in key points, securing the necessary components to the board and completing the connections.

Wave soldering is a versatile process, as wave soldering machines are capable of simple joints - such as merely dragging a board and components through the wave - or complicated soldering, as many machines are cad-operated and can tilt boards through solder nozzles by tilting the board on all three axes.

However, wave soldering has some drawbacks. It isn't the most ideal for high-volume operations as it can be time-consuming. It can also be hazardous for surface mount components as the solder can be reflowed and the component can fall off or a faulty joint can be created. Additionally, not all wave machines are capable of super-fine joints.

That said, wave soldering is very well suited to and in fact the default soldering methods for soldering boards that contain through-hole components. Through-hole components are no longer the dominant component type (surface-mount is) but are still widely used when a component is required with a high number of pin connectors or that uses a lot of power.

The default method of soldering for almost all of human history has been hand soldering, though in recent decades hand soldering has obviously been replaced. However, there is still a place for it. Hand soldering is a craft in every sense of the term, as there are an art and a science to hand soldering.

Painstaking precision and detail are possible with hand-soldering, as are certain joints that computer-controlled selective or reflow machines are just not capable of.

However, there are some drawbacks to hand soldering. There aren't too many products that require it over selective soldering methods or reflow soldering. Additionally, there are fewer people entering the field (largely because of that reason) and training a person until they are capable of the utmost of precision hand soldering is time-intensive and expensive, which has led the industry to produce fewer and fewer of these tradespersons. It is also a slower process than automated soldering, which is a hindrance when high-volume production is required.

Laser soldering is similar to reflow in a way, in that solid solder is deposited on a board which is then heated until it flows, completed the solder joint. However, it is done (obviously) by a laser in a very specific location.

Laser soldering is the ultimate in precision and flexibility. Through-hole and surface mount components alike can be laser-soldered. Multiple solder types - both lead-free and tin-lead solders can be used with minimal tooling required - can be employed. The level of precision is unmatched by any other type. Additionally, laser soldering poses fewer risks as it's akin to employing a scalpel rather than a broadsword. Laser soldering is also lightning fast compared to other soldering applications.

However, laser soldering systems can also be costly and require highly-trained technicians to maintain. 

If you are wondering which soldering method is best for your business needs, give our consultants a call. We love to talk machines, call us @ 509.891.1680 or contact us