Picking The Right Solder For Selective Soldering

Along with choosing the right selective soldering machine, it’s also essential that you choose the right solder for the application that you’ll be using it for. Solder, in and of itself, is an alloy. Like other alloys, its properties – especially conductance, resistance and hardiness – depend on the composition. 

Which solder is appropriate depends on the application. The solder that your product requires will depend entirely upon the product itself and how it is being assembled. Some solders work better with reflow, others with selective soldering and so on. 

Let us consider the factors you’ll need to examine. 

Solder Conductivity

One consideration to make is conductivity. Obviously, any components being soldered require a consistent current being available, but some components require a stronger connection than others. Therefore, consider the components you’re assembling and the needs of electricity. 

Every solder has its own conductive properties based on the compositional alloy. Lead-free solders, for instance, are known for being less conductive in many cases than leaded solders for the most part. However, there are lead-free solders that are far more conductive than others. 

If your business demands that lead-free solder be used – and there are many reasons to consider it – be sure to select the right lead-free solder if your product requires a high degree of conductivity. 

Leaded solders, however, are known for being far more conductive. One of the benchmark solder alloys is a 60/40 of tin-lead; for most solder makers, these products are commonly their bread and butter. 

Therefore, make sure you’re aware of what sort of conductivity is critical to your components before choosing a solder to use with your selective soldering machine

Solder Temperature When Selective Soldering

Temperature management during selective soldering is critical. The board must be sufficiently preheated in order to prevent thermal shock and breakage and sufficient heat must be present in order for solder to flow correctly…but too high of heat can warp or otherwise damage the board and components. 

Depending on the board you’re using and the components, you may have to select a solder alloy that requires a relatively lower temperature than higher temperature, as the temperature of the solder once it contacts the board makes an impact. 

Lead-free solders require higher temperatures, leaden solders flow at lower temperatures. If selective soldering, this aspect is very important in order to ensure consistent, quality product. 

Selective Soldering Maintenance And Waste Disposal

Another factor, of course, is also the maintenance time that can be allotted to a selective soldering machine and the solder pots, as well as waste disposal. Some operations are able to absorb longer cycles where a machine is down for cleaning and regular maintenance. Others require high volume of production that cannot stop for longer. 

Some solders require longer cleaning and maintenance cycles, depending on the composition. Unless your selective soldering system can have more time devoted to it, make sure that the solder you’ve selected as well as the selective soldering system you have chosen allow for quick turnaround during downtime. 

Additionally, be aware of waste disposal needs. Lead and other materials require a greater standard of care for disposal as lead – and other materials present in the soldering process – can be toxic. If your business cannot absorb the greater cost of waste disposal due to harsh chemicals, make sure to select a solder with an appropriate composition.